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Joint Albedo Estimation and Pose Tracking from Video

IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2013年第7期35卷 1674-1689页

作者： Taheri, Sima Sankaranarayanan, Aswin C. Chellappa, Rama Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Rice Univ Dept Elect & Comp Engn Houston TX 77251 USA Univ Maryland Dept Elect & Comp Engn Ctr Automat Res College Pk MD 20742 USA

The albedo of a Lambertian object is a surface property that contributes to an object's appearance under changing illumination. As a signature independent of illumination, the albedo is useful for object recognition. Single image-based albedo estimation algorithms suffer due to shadows and non-Lambertian effects of the image. In this paper, we propose a sequential algorithm to estimate the albedo from a sequence of images of a known 3D object in varying poses and illumination conditions. We first show that by knowing/estimating the pose of the object at each frame of a sequence, the object's albedo can be efficiently estimated using a Kalman filter. We then extend this for the case of unknown pose by simultaneously tracking the pose as well as updating the albedo through a Rao-Blackwellized particle filter (RBPF). More specifically, the albedo is marginalized from the posterior distribution and estimated analytically using the Kalman filter, while the pose parameters are estimated using importance sampling and by minimizing the projection error of the face onto its spherical harmonic subspace, which results in an illumination-insensitive pose tracking algorithm. Illustrations and experiments are provided to validate the effectiveness of the approach using various synthetic and real sequences followed by applications to unconstrained, video-based face recognition.

关键词： Albedo pose tracking spherical harmonics sequential algorithm Kalman filter Rao-Blackwellized particle filter intrinsic image statistics

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Computing regularities in strings: A survey

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EUROPEAN JOURNAL OF COMBINATORICS 2013年第1期34卷 3-14页

作者： Smyth, W. F. McMaster Univ Dept Comp & Software Algorithms Res Grp Hamilton ON L8S 4K1 Canada

The aim of this survey is to provide insight into the sequential algorithms that have been proposed to compute exact "regularities" in strings;that is, covers (or quasiperiods), seeds, repetitions, runs (or maximal periodicities), and repeats. After outlining and evaluating the algorithms that have been proposed for their computation, I suggest possibly productive future directions of research. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Exact Insight sequential algorithm Cosmic strings

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A two-pheromone trail ant colony system-tabu search approach for the heterogeneous vehicle routing problem with time windows and multiple products

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JOURNAL OF HEURISTICS 2013年第2期19卷 233-252页

作者： De la Cruz, Jair J. Paternina-Arboleda, Carlos D. Cantillo, Victor Montoya-Torres, Jairo R. Univ Norte Dept Ind Engn Barranquilla Colombia Univ Norte Escuela Negocios Barranquilla Colombia Univ Norte Dept Civil & Environm Engn Barranquilla Colombia Univ La Sabana Escuela Ciencias Econ & Adm Chia Cundinamarca Colombia

This paper considers a practical variant of the Vehicle Routing Problem (VRP) known as the Heterogeneous Vehicle Routing Problem with Time Windows and Multiple Products (HVRPTWMP). As the problem is NP-hard, the resolution approach proposed here is a sequential Ant Colony System (ACS)-Tabu Search algorithm. The approach introduces a two pheromone trail strategy to accelerate agents' (ants) learning process. Its convergence to good solutions is given in terms of fleet size and travel time while completing tours and service to all customers. The proposed procedure uses regency and frequency memories form Tabu Search to further improve the quality of solutions. Experiments are carried out using instances from literature and show the effectiveness of this procedure.

关键词： Vehicle routing Multiple products Time windows Ant colony Tabu search sequential algorithm

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Less is More: Video Trimming for Action Recognition

Less is More: Video Trimming for Action Recognition

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IEEE International Conference on Computer Vision (ICCV)

作者： Antic, Borislav Milbich, Timo Ommer, Bjoern Heidelberg Univ Heidelberg Collaboratory Image Proc D-69115 Heidelberg Germany

ISBN: (纸本)9781479930227

Action recognition is an important precursor for understanding human activities in videos. The current paradigm of action recognition is to classify a video sequence as a whole. However, actions usually occur only in part of a video sequence, rendering the rest of the video irrelevant for action recognition. In this paper, we propose a method for learning a subsequence classifier which can detect and classify part of a video that corresponds to the action. The subsequence classifier is trained from weakly labeled training videos whose subsequence labels are not provided, but need to be inferred during learning. We use the framework of multiple instance learning to solve two problems jointly: i) find the action subsequences in training videos, ii) train the subsequence classifier using the inferred action subsequences. To obtain a robust solution to the MIL problem, we propose a sequential algorithm that consecutively decreases the number of inferred action subsequences per video and trims their length until only one short subsequence is used as the action representative in each video. We evaluate the combination of the automatically trained subsequence classifier and the full sequence classifier on the very challenging Hollywood2 benchmark set and observe a significant gain in the performance over the baseline full sequence classifier. Moreover, a favorable performance of the subsequence classifier for temporal localization of actions in videos is evidenced on two categories of the Hollywood2 dataset.

关键词： action recognition multiple instance learning video analysis Videotapes Classifiers Video sequences Action trimmings VIDEO ANALYSIS Training Videos Recognition (Psychology) sequential algorithm Robust solution

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sequential LOCAL FRI SAMPLING OF INFINITE STREAMS OF DIRACS

SEQUENTIAL LOCAL FRI SAMPLING OF INFINITE STREAMS OF DIRACS

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Jon Onativia Jose Antonio Uriguen Pier Luigi Dragotti Department of Electrical and Electronic Engineering Imperial College London

ISBN: (纸本)9781479903573

The theory of sampling signals with finite rate of innovation (FRI) has shown that it is possible to perfectly recover classes of non-bandlimited signals such as streams of Diracs from uniform samples. Most of previous papers, however, have to some extent only focused on the sampling of periodic or finite duration signals. In this paper we propose a novel method that is able to reconstruct infinite streams of Diracs, even in high noise scenarios. We sequentially process the discrete samples and output locations and amplitudes of the Diracs in real-time. We first establish conditions for perfect reconstruction in the noiseless case and then present the sequential algorithm for the noisy scenario. We also show that we can achieve a high reconstruction accuracy of 1000 Diracs for SNRs as low as 5dB.

关键词： Analog-to-digital conversion Finite rate of innovation Sampling theory Annihilating filter Analog-digital conversion streams Sampling sequential algorithm perfect reconstruction Paul Adrien Maurice Dirac rivers signals Noise

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Distributed Approximation algorithms for Maximum Link Scheduling and Local Broadcasting in the Physical Interference Model

Distributed Approximation Algorithms for Maximum Link Schedu...

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IEEE INFOCOM

作者： Guanhong Pei Anil Kumar S. Vullikanti Dept. of Electrical and Computer Engineering and Virginia Bioinformatics Institute Virginia Tech Blacksburg VA USA Dept. of Computer Science and Virginia Bioinformatics Institute Virginia Tech Blacksburg VA USA

ISBN: (纸本)9781467359443

In this paper, we develop the first rigorous distributed algorithm for link scheduling in the SINR model under any length-monotone sub-linear power assignments. Our algorithms give constant factor approximation guarantees, matching the bounds of the sequential algorithms for these problems, with provable bounds on the running time in terms of the graph topology. We also study a related and fundamental problem of local broadcasting for uniform power levels, and obtain similar bounds. These problems are much more challenging in the SINR model than in the more standard graph based interference models, because of the non-locality of the SINR model. Our algorithms are randomized and crucially rely on physical carrier sensing for the distributed communication steps. We find that the specific wireless device capability of duplex/half-duplex communication significantly impacts the performance. Our main technique involves the distributed computation of affectance and a construct called a ruling, which are likely to be useful in other scheduling problems in the SINR model. We also study the empirical performance of our algorithms, and find that the performance depends on the topology, and the approximation ratio is very close to the best sequential algorithm.

关键词： SINR Approximation algorithms sequential algorithm disturbance patterns Bound algorithms topology carrier sense

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Primary User Traffic Classification in Dynamic Spectrum Access Networks

Primary User Traffic Classification in Dynamic Spectrum Acce...

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IEEE Global Communications Conference

作者： Chun-Hao Liu Eric Rebeiz Przemyslaw Pawelczak Danijela Cabric University of California Los Angeles Engineering IV Building Delft University of Technology

ISBN: (纸本)9781479913510

We propose a primary user (PU) traffic distribution classifier for dynamic spectrum access networks based on multi-hypothesis sequential probability ratio test (MSPRT). In specific, we propose two classifiers: (i) an estimate-then-classify classifier, and (ii) a modified MSPRT classifier based on the average likelihood function considering partial knowledge of the PU traffic parameters. Using the sequential algorithm, we show that our proposed classifiers can achieve higher classification performance compared to the traditional maximum likelihood classifier using constant number of samples.

关键词： Classifiers access network Dynamic spectrum access traffic classification sequential algorithm sprt Likelihood Functions Plutonium Traffic distribution

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An adaptive mesh refinement algorithm for compressible two-phase flow in porous media

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COMPUTATIONAL GEOSCIENCES 2012年第3期16卷 577-592页

作者： Pau, George Shu Heng Bell, John B. Almgren, Ann S. Fagnan, Kirsten M. Lijewski, Michael J. Univ Calif Berkeley Lawrence Berkeley Natl Lab Div Earth Sci Berkeley CA 94720 USA Univ Calif Berkeley Lawrence Berkeley Natl Lab Ctr Computat Sci & Engn Berkeley CA 94720 USA Univ Calif Berkeley Lawrence Berkeley Natl Lab Natl Energy Res Sci Comp Ctr Berkeley CA 94720 USA

We describe a second-order accurate sequential algorithm for solving two-phase multicomponent flow in porous media. The algorithm incorporates an unsplit second-order Godunov scheme that provides accurate resolution of sharp fronts. The method is implemented within a block structured adaptive mesh refinement (AMR) framework that allows grids to dynamically adapt to features of the flow and enables efficient parallelization of the algorithm. We demonstrate the second-order convergence rate of the algorithm and the accuracy of the AMR solutions compared to uniform fine-grid solutions. The algorithm is then used to simulate the leakage of gas from a Liquified Petroleum Gas (LPG) storage cavern, demonstrating its capability to capture complex behavior of the resulting flow. We further examine differences resulting from using different relative permeability functions.

关键词： Adaptive mesh refinement Compressible two-phase flow Porous media sequential algorithm

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Minimum average-case queries of q+1-ary search game with small sets

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DISCRETE APPLIED MATHEMATICS 2012年第4-5期160卷 618-627页

作者： Meng, Kun Lin, Chuang Liu, Wen An Yang, Yang Katona, Gyula O. H. Univ Sci & Technol Beijing Sch Comp & Commun Engn Beijing 100083 Peoples R China Tsinghua Univ Dept Comp Sci & Technol Beijing 100084 Peoples R China Henan Normal Univ Coll Math & Informat Sci Xinxiang Peoples R China Renyi Inst Budapest Budapest Hungary

Given a search space S = {1,2,..., n}, an unknown element x* is an element of S and fixed integers l >= 1 and q >= 1, a q + 1-ary l-restricted query is of the following form: which one of the set {A(0), A(1),..., A(q)} is the x* in?, where (A(0), A(1), ..., A(q)) is a partition of S and vertical bar A(i)vertical bar <= e for i = 1, 2,...,q. The problem of finding x. from S with q + 1-ary size-restricted queries is called as a q + 1-ary search game with small sets. In this paper, we consider sequential algorithms for the above problem, and establish the minimum number of average-case sequential queries when x*. satisfies the uniform distribution on S. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Search game sequential algorithm Average-cost Huffman tree

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Treatment of spondylodiscitis

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INTERNATIONAL ORTHOPAEDICS 2012年第2期36卷 405-411页

作者： Zarghooni, Kourosh Roellinghoff, Marc Sobottke, Rolf Eysel, Peer Univ Cologne Dept Orthopaed & Trauma Surg ZKS BMBF 01KN1106 D-50931 Cologne Germany Univ Halle Wittenberg Dept Orthopaed & Trauma Surg Halle Germany

Pyogenic infections of the spine are relatively rare with an incidence between 1:100,000 and 1:250,000 per year, but the incidence is increasing due to increases in average life-expectancy, risk factors, and medical comorbidities. The mean time in hospital varies from 30 to 57 days and the hospital mortality is reported to be 2-17%. This article presents the relevant literature and our experience of conservative and surgical treatment of pyogenic spondylodiscitis. We have performed a review of the relevant literature and report the results of our own research in the diagnosis and treatment of pyogenic spondylodiscitis. We present a sequential algorithm for identification of the pathogen with blood cultures, CT-guided biopsies and intraoperative tissue samples. Basic treatment principles and indications for surgery and our surgical strategies are discussed. Recent efforts have been directed toward early mobilisation of patients using primary stable surgical techniques that lead to a further reduction of the mortality. Currently our hospital mortality in patients with spondylodiscitis is around 2%. With modern surgical and antibiotic treatment, a relapse of spondylodiscitis is unlikely to occur. In literature the relapse rate of 0-7% has been recorded. Overall the quality of life seems to be more favourable in patients following surgical treatment of spondylodiscitis. With close clinical and radiological monitoring of patients with spondylodiscitis, conservative and surgical therapies have become more successful. When indicated, surgical stabilisation of the infected segments is mandatory for control of the disease and immediate mobilisation of the patients.

关键词： Patients Surgery sequential algorithm Discitis Hospital Mortality Conservative Operative Surgical Procedures

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