Research Publications

 Search | Show all AllJournal Publication Narrow your search « 1 »Results per Page 10 25 50 100 25062 result(s) By TypeShow all typesBy Year2013 (1)2012 (11)2011 (20)2010 (5)2009 (5)By Research GroupShow all research groups Lauren Gardner, Melissa Duell, S. Travis WallerThe introduction of plug-in electric vehicles (PEVs) represents an unprecedented interaction between the road network and electricity grid. By replacing the traditional fuel source, petrol, with electricity, PEVs will increase the demand for electric ...Transportation Research Part A: Policy and Practice - March 2013 Siyuan Chen, Julien EppsMeasuring cognitive load changes can contribute to better treatment of patients, can help design effective strategies to reduce medical errors among clinicians and can facilitate user evaluation of health care information systems. This paper proposes an ...Computer Methods and Programs in Biomedicine - December 2012 Fang Chen, Natalie Ruiz, M. Asif Khawaja, Ho (Eric) Choi, Julien Epps, Ronnie Taib, Bo Yin, Yang WangHigh cognitive load arises from complex time- and safety-critical tasks (e.g., mapping out flight paths, monitoring traffic, or even managing nuclear reactors), which cause stress, errors and diminished performance. Over the past five years, our research ...ACM Transactions on Interactive Intelligent Systems - December 2012 Julian McAuley, Arnau Ramisa, Tiberio CaetanoThe recently proposed ImageNet dataset consists of several million images, each annotated with a single object category. These annotations may be imperfect, in the sense that many images contain multiple objects belonging to the label vocabulary. In ...International Journal of Computer Vision (IJCV) - September 2012 Tapio Pahikkala, Hanna Suominen, Jorma BobergWe propose an efficient algorithm for calculating hold-out and cross-validation (CV) type of estimates for sparse regularized least-squares predictors. Holding out H data points with our method requires O(min(nH^2,Hn^2)) time provided that a predictor ...Machine Learning - July 2012 Coles Amanda, Coles Andrew, Angel Garcia Olaya, Sergio Jimenez, Carlos Linares Lopez, Scott Sanner, Sungwook YoonIn this article we review the 2011 International Planning Competition. We give an overview of the history of the competition, discussing how it has developed since its first edition in 1998. The 2011 competition was run in three main separate tracks: ...AI Magazine - June 2012 Andrey Kan, Jeffrey Kai Chi Chan, Conor Hayes, Bernie Hogan, James Bailey, Chris LeckieOnline forums are rich sources of information about users' communication activity over time. Finding temporal patterns in communication records can advance our understanding of the dynamics of conversations. The main challenge of temporal analysis in ...World Wide Web - May 2012 Tim Van Erven, Mark Reid, Bob WilliamsonMixability of a loss governs the best possible performance when aggregating expert predictions with respect to that loss. The determination of the mixability constant for binary losses is straightforward but opaque. In the binary case we make this ...Journal of Machine Learning Research - May 2012 Julian McAuley, Tiberio CaetanoThe problem of isometric point-pattern matching can be modeled as inference in small tree-width graphical models whose embeddings in the plane are said to be ‘globally rigid’. Although such graphical models lead to efﬁcient and exact solutions, they ...Pattern Recognition - May 2012 Background: This work describes a system for identifying event mentions in bio-molecular research abstracts that are either speculative (e.g. analysis of IkappaBalpha phosphorylation, where it is not specified whether phosphorylation did or did not occur...BMC Medical Informatics and Decision Making - April 2012 Junbin Gao, Qinfeng Shi, Tiberio CaetanoCompressive sensing is an emerging ﬁeld predicated upon the fact that, if a signal has a sparse representation in some basis, then it can be almost exactly reconstructed from very few random measurements. Many signals and natural images, for example ...Pattern Recognition Letters - February 2012 The two parameter Poisson-Dirichlet Process (PDP), a generalisation of the Dirichlet Process, is increasingly being used for probabilistic modelling in discrete areas such as language technology, bioinformatics, and image analysis. There is a rich ...ARXIV - February 2012 Richard Medland, Petromil PetkovEnvironmental issues have become more salient in the global political and social consciousness, leading to Human-Computer Interaction research exploring solutions to environment imbalances and climate change. IEEE Pervasive Computing: Special Issue on Pervasive Computing for Smart Energy Systems - October 2011 Mark Reid, Bob WilliamsonWe study losses for binary classifi cation and class probability estimation and extend the understanding of them from margin losses to general composite losses which are the composition of a proper loss with a link function. We characterise when margin...Journal of Machine Learning Research (JMLR) - September 2010 Mohammad Ali Abam, Mark de Berg, Mohammad Farshi, (Hans) Joachim Gudmundsson, Michiel SmidLet (S, d) be a finite metric space, where each element p 2 S has a non-negative weight wt(p). We study t-spanners for the set S with respect to the following weighted distance function d!: d!(p, q) = 0 if p = q, wt(p) + d(p, q) + wt(q) if p 6= q....Algorithmica - September 2011 Andrey Kan, James Bailey, Chris Leckie, John Markham, Mark Dowling, Rajib ChakravortyAbstract Cell tracking is a key task in the high-throughput quantitative study of important biological processes, such as immune system regulation and neurogenesis. Variability in cell density and dynamics in different videos, hampers portability of ...Journal of Microscopy - September 2011 (Hans) Joachim Gudmundsson, Pat Morin, Michiel SmidAlgorithms for determining quality/cost/price tradeo ffs in saturated markets are considered. A product is modeled by d real-valued qualities whose sum determines the unit cost of producing the product. This leads to the following optimization problem: ...Algorithmica - August 2011 Bojan Djordjevic, (Hans) Joachim Gudmundsson, Anh Pham, Thomas WolleWe are given a trajectory $\T$ and an area $\A$. $\T$ might intersect $\A$ several times, and our aim is to detect whether $\T$ visits $\A$ with some regularity, e.g.~what is the longest time span that a GPS-GSM equipped elephant visited a specific lake...Algorithmica - August 2011 Helen Allvin, Elin Carlsson, Hercules Dalianis, Riitta Danielsson-Ojala, Vidas Daudaravičius, Martin Hassel, Dimitrios Kokkinakis, Heljä Lundgrén-Laine, Gunnar Nilsson, Øystein Nytrø, Sanna Salanterä, Maria Skeppstedt, Hanna Suominen, Sumithra VelupillaiBackground Free text is helpful for entering information into electronic health records, but reusing it is a challenge. The need for language technology for processing Finnish and Swedish healthcare text is therefore evident; however Finnish and ...Journal of Biomedical Semantics - August 2011 Bader Aljaber, David Martinez, Nicola Stokes, James BaileyMedical Subject Headings (MeSH) are used to index the majority of databases generated by the National Library of Medicine. Essentially, MeSH terms are designed to make information, such as scientific articles, more retrievable and assessable to users of...Journal of Biomedical Informatics - June 2011 Vida Dujmovic, (Hans) Joachim Gudmundsson, Pat Morin, Thomas WolleA graph $G$ is an $\alpha$ angle crossing ($\alpha$AC) graph if every pair of crossing edges in $G$ intersect at an angle of at least $\alpha$. The concept of right angle crossing (RAC) graphs ($\alpha=\pi/2$) was recently introduced by Didimo \etal\ ...Chicago Journal of Theoretical Computer Science - May 2011 Maximum A Posteriori inference in graphical models is often solved via message-passing algorithms, such as the junction-tree algorithm or loopy belief-propagation. The exact solution to this problem is well-known to be exponential in the size of the ...Journal of Machine Learning Research (JMLR) - April 2011 Karina Valdivia Delgado, Leliane Nunes de Barros, Fabio Gagliardi Cozman, Scott SannerThis paper investigates Factored Markov Decision Processes with Imprecise Probabilities (MDPIPs); that is, Factored Markov Decision Processes (MDPs) where transition probabilities are imprecisely specified. We derive efficient approximate solutions for...International Journal of Approximate Reasoning - April 2011 Phu Ngoc Le, Eliathamby Ambikairajah, Julien Epps, Vidhyasaharan Sethu, Ho (Eric) ChoiSpeech is a promising modality for the convenient measurement of cognitive load, and recent years have seen the development of several cognitive load classification systems. Many of these systems have utilised mel Frequency Cepstral Coefficients (MFCC) ...Speech Communication - April 2011 SuNam Kim, David Martinez, Lawrence Cavedon, Lars YenckenAIM: Given a set of pre-defined medical categories used in Evidence Based Medicine, we aim to automatically annotate sentences in medical abstracts with these labels. METHOD: We constructed a corpus of 1,000 medical abstracts annotated by hand with ...BMC Bioinformatics - March 2011 David Martinez, Tim BaldwinThis paper describes a method for detecting event trigger words in biomedical text based on a word sense disambiguation (WSD) approach. We first investigate the applicability of existing WSD techniques to trigger word disambiguation in the BioNLP 2009 ...BMC Bioinformatics - March 2011 We unify f-divergences, Bregman divergences, surrogate regret bounds, proper scoring rules, cost curves, ROC-curves and statistical information. We do this by systematically studying integral and variational representations of these objects and in so ...Journal of Machine Learning Research (JMLR) - March 2011 Tet Fei Yap, Julien Epps, Eliathamby Ambikairajah, Ho (Eric) ChoiCognitive load measurement systems measure the mental demand experienced by human while performing a cognitive task, which is useful in monitoring and enhancing task performance. Various speech-based systems have been proposed for cognitive load ...EURASIP Journal on Advances in Signal Processing - Jan 2011 Masud Moshtaghi, T. Havens, JC. Bezdek, Laurence Park, Chris Leckie, S. Pajasegarar, JM. Keller, M. PalaniswamiPattern Recognition - January 2011 Karina Delgado, Scott Sanner, Leliane Nunes de BarrosWhen modeling real-world decision-theoretic planning problems in the Markov Decision Process (MDP) framework, it is often impossible to obtain a completely accurate estimate of transition probabilities. For example, natural uncertainty arises in the ...Artificial Intelligence - January 2011 Joel Veness, Kee Siong Ng, Marcus Hutter, William Uther, David SilverThis paper introduces a principled approach for the design of a scalable general reinforcement learning agent. Our approach is based on a direct approximation of AIXI, a Bayesian optimality notion for general reinforcement learning agents. Previously, it ...Journal of Artificial Intelligence Research - January 2011 Mohaddeseh Nosratighods, Eliathamby Ambikairajah, Julien Epps, Michael CareyThe performance of speaker verification systems degrades considerably when the test segments are utterances of very short duration. This might be either due to variations in score-matching arising from the unobserved speech sounds of short speech ...Speech Communication - September 2010 Bo Yin, Eliathamby Ambikairajah, Fang ChenDeveloping a fusion-based system is one of the key research issues in modern Language Identification (LID) systems. In this paper we investigate existing fusion techniques for LID systems and propose an alternative solution.By directly utilizing ... - May 2010 Teddy Gunawan, Eliathamby Ambikairajah, Julien EppsThe use of simultaneous masking in speech enhancement has shown promise for a range of noise types. In this paper, a new speech enhancement algorithm based on a short-term temporal masking threshold to noise ratio (MNR) is presented. A novel functional ...Speech Communication - May 2010 Marc Benkert, Bojan Djordjevic, (Hans) Joachim Gudmundsson, Thomas WolleWidespread availability of location aware devices (such as GPS receivers) promotes capture of detailed movement trajectories of people, animals, vehicles and other moving objects. We investigate spatio-temporal movement patterns in large tracking data ... - February 2010 Hans L. Bodlaender, Corinne Feremans, Alexander Grigoriev, Eelko Penninkx, Rene Sitters, Thomas WolleIn this paper we discuss the complexity and approximability of the minimum corridor connection problem where, given a rectilinear decomposition of a rectilinear polygon into rooms'', one has to find the minimum length tree along the edges of the ... (Hans) Joachim Gudmundsson, Jyrki Katajainen, Damian Merrick, Cahya Ong, Thomas WolleA trajectory is a sequence of locations, each associated with a timestamp, describing the movement of a point. Trajectory data is becoming increasingly available and the size of recorded trajectories is getting larger. In this paper we study the problem ... - February 2009 Novi Quadrianto, Alex J. Smola, Tiberio Caetano, Quoc LeConsider the following problem: given sets of unlabeled observations, each set with known label proportions, predict the labels of another set of observations, possibly with known label propor- tions. This problem occurs in areas like e-commerce, ...Journal of Machine Learning Research - November 2009 Qinfeng Shi, James Petterson, Gideon Dror, John Langford, Alex Smola, Vishy VishwanathanWe propose hashing to facilitate eﬃcient kernels. This generalizes previous work using sampling and we show a principled way to compute the kernel matrix for data streams and sparse feature spaces. Moreover, we give deviation bounds from the exact ...Journal of Machine Learning Research - Special Topic on Large Scale Learning Tiberio Caetano, Julian McAuley, Li Cheng, Quoc Le, Alex SmolaAs a fundamental problem in pattern recognition, graph matching has applications in a variety of fields, from computer vision to computational biology. In graph matching, patterns are modeled as graphs and pattern recognition amounts to finding a ...IEEE Transactions on Pattern Analysis and Machine Intelligence - June 2009 It has been shown that isometric matching problems can be solved exactly in polynomial time, by means of a Junction Tree with small maximal clique size. Recently, an iterative algorithm was presented which converges to the same solution an order of ...Spatial Vision - May 2009 Tharmarajah Thiruvaran, Mohaddeseh Nosratighods, Eliathamby Ambikairajah, Julien EppsRecently, subband frame-averaged frequency modulation (FM) as a complementary feature to amplitude-based features for several speech based classification problems including speaker recognition has shown promise. One problem with using FM extraction in ...IET Electronics Letter - March 2009 Mattias Andersson, (Hans) Joachim Gudmundsson, Patrick Laube, Thomas WolleWidespread availability of location aware devices (such as GPS receivers) promotes capture of detailed movement trajectories of people, animals, vehicles and other moving objects, opening new options for a better understanding of the processes involved.... - October 2007 Julian McAuley, Tiberio Caetano, Marconi BarbosaA recent paper [1] proposed a provably optimal polynomial time method for performing near-isometric point pattern matching by means of exact probabilistic inference in a chordal graphical model. Its fundamental result is that the chordal graph in ... - November 2008 Hee-Kap Ahn, Sang-Won Bae, Otfried Cheong, (Hans) Joachim GudmundssonThe aperture angle a(x,Q) of a point x in Q in the plane with respect to a convex polygon Q is the angle of the smallest cone with apex x that contains Q. The aperture angle approximation error of a compact convex set C in the plane with respect to an ... - October 2008 Boris Aronov, Mark de Berg, Otfried Cheong, (Hans) Joachim Gudmundsson, Herman Haverkort, Michiel Smid, Antoine VigneronGiven a set S of n points in R^D, and an integer k such that 0 < k < n, we show that a geometric graph with vertex set S, at most n − 1 + k edges, maximum degree five, and dilation O(n/(k + 1)) can be computed in time O(n log n). For any k, we also ... - August 2008 Boris Aronov, Mark de Berg, Otfried Cheong, Herman Haverkort, Antoine VigneronGiven a set S of n points in d dimensional Euclidean space, and an integer k such that 0 <= k < n, we show that a geometric graph with vertex set S, at most n − 1 + k edges, maximum degree five, and dilation O(n/(k + 1)) can be computed in time O(n log n)... - August 2008 Marc Benkert, (Hans) Joachim Gudmundsson, Herman Haverkort, Alexander WolffA wireless ad-hoc network can be represented as a graph in which the nodes represent wireless devices, and the links represent pairs of nodes that communicate directly by means of radio signals. The interference caused by a link between two nodes u and v... - August 2008 Tommer Leyvand, Daniel Cohen-Or , Gideon Dror, Dani LischinskiWhen human raters are presented with a collection of shapes and asked to rank them according to their aesthetic appeal, the results often indicate that there is a statistical consensus among the raters. Yet it might be difﬁcult to deﬁne a succinct ... - August 2008 Mohammad Farshi, Panos Giannopoulos, (Hans) Joachim GudmundssonGiven a Euclidean graph G in R^d with n vertices and m edges, we consider the problem of adding an edge to G such that the stretch factor of the resulting graph is minimized. Currently, the fastest algorithm for computing the stretch factor of a graph ... - April 2008 (Hans) Joachim Gudmundsson, Christos Levcopoulos, Giri Narasimhan, Michiel SmidGiven an arbitrary real constant \eps > 0, and a geometric graph G in d-dimensional Euclidean space with n points, O(n) edges, and constant dilation, our main result is a data structure that answers (1+\eps)-approximate shortest path length queries in ... - March 2008 Marc Benkert, (Hans) Joachim Gudmundsson, Florian Hübner, Thomas WolleData representing moving objects is rapidly getting more available, especially in the area of wildlife GPS tracking. It is a central belief that information is hidden in large data sets in the form of interesting patterns, where a pattern can be any ... - November 2008 (Hans) Joachim Gudmundsson, Christos LevcopoulosWe consider the problem of computing a minimum weight pseudo-triangulation of a set S of n points in the plane. We first present an O(n log n)-time algorithm that produces a pseudo-triangulation of weight O(log n * wt(M(S))) which is shown to be ... - October 2007 Julian McAuley, Luciano da Fontoura Costa, Tiberio CaetanoThe "rich-club phenomenon" in complex networks is characterized when nodes of higher degree are more interconnected than nodes with lower degree. The presence of this phenomenon may indicate several interesting high-level network properties, such as ...Applied Physics Letters - August 2007 Mattias Andersson, (Hans) Joachim Gudmundsson, Christos LevcopoulosLet H1 = (V,E1) be a collection of N pairwise vertex disjoint O(1)-spanners where the weight of an edge is equal to the Euclidean distance between its endpoints. Let H2 = (V,E2) be the graph on V with M edges of non-negative weight. The union of the two ... - August 2007 (Hans) Joachim Gudmundsson, Marc van Kreveld, Bettina SpeckmannMoving point object data can be analyzed through the discovery of patterns. We consider the computational e±ciency of detecting four such spatio-temporal patterns, namely flock, leadership, convergence, and encounter, as defined by Laube et al., 2004. ... - June 2007 (Hans) Joachim Gudmundsson, Giri Narasimhan, Michiel SmidGiven a polygonal path P with vertices p1, , pn in R^d and a real number t>1, a path Q = (pi1, pi2, , pik) is a t-distance preserving approximation of P if 1 = i1 < i2 < < ik = n and each straight-line edge (pij ; pij+1) of Q approximates the ... - April 2007 M. Asif Khawaja, Fang Chen, Nadine MarcusObjective: Analyses of novel linguistic and grammatical features, extracted from transcribed speech of people working in collaborative environment, for cognitive load measurement. Background: Prior studies have attempted to assess users’ cognitive load ...Journal of Human Factors and Ergonomic Society - 2011 Zhidong Li, Weihong Wang, Yang Wang, Fang Chen, Yi WangIn this paper, we propose a biologically inspired framework of visual tracking based on proto-objects. Given an image sequence, proto-objects are first detected by combining saliency map and topic model. Then the target is tracked based on spatial and ...Pattern Recognition (PR) - November 2011 Siyuan Chen, Julien EppsIEEE Pervasive Computing Sazzad Hussain, Rafael Calvo, Fang ChenWe experience cognitive load, i.e. in the executive control of working memory, during critical tasks and other activities such as learning. While engaged in these activities our affective states i.e. emotions, can be induced by the task itself or by ...Interacting with Computers