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robust adaptive spread-spectrum receiver with neural-net preprocessing in non-Gaussian noise

IEEE TRANSACTIONS ON NEURAL NETWORKS 2001年第3期12卷 546-558页

作者： Chuah, TC Sharif, BS Hinton, OR Univ Newcastle Upon Tyne Dept Elect & Elect Engn Newcastle Upon Tyne NE1 7RU Tyne & Wear England

Multiuser communications channels based on code division multiple access (CDMA) technique exhibit non-Gaussian statistics due to the presence of highly structured multiple access interference (MAI) and impulsive ambient noise. Linear adaptive interference suppression techniques are attractive for mitigating MAI under Gaussian noise. However, the Gaussian noise hypothesis has been found inadequate in many wireless channels characterized by impulsive disturbance. Linear finite impulse response (Fm) filters adapted with linear algorithms are limited by their structural formulation as a simple linear combiner with a hyperplanar decision boundary, which are extremely vulnerable to impulsive interference. This raises the issues of devising robust reception algorithms accounting at the design stage the non-Gaussian behavior of the interference. In this paper we propose a novel multiuser receiver that involves an adaptive nonlinear preprocessing front-end based on multilayer perceptron neural-network, which acts as a mechanism to reduce the influence of impulsive noise followed by a postprocessing stage using linear adaptive filters for MAI suppression. Theoretical arguments supported by promising simulation results suggest that the proposed receiver, which combines the relative merits of both nonlinear and linear signal processing, presents an effective approach for joint suppression of MAI and non-Gaussian ambient noise.

关键词： alpha-stable distributions influence functions multilayer perceptrons non-Gaussian noise nonlinear receiver robust algorithms

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Identifying outbreaks in sewer networks: An adaptive sampling scheme under network's uncertainty

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2024年第14期121卷 1页

作者： Baboun, Jose Beaudry, Isabelle S. Castro, Luis M. Gutierrez, Felipe Jara, Alejandro Rubioa, Benjamin Verschaea, Jose Pontificia Univ Catolica Chile Inst Math & Computat Engn Fac Matemat Santiago 7820436 Chile Pontificia Univ Catolica Chile Inst Math & Computat Engn Fac Ingn Santiago 7820436 Chile Mt Holyoke Coll Dept Math & Stat South Hadley MA 01075 USA Pontificia Univ Catolica Chile Dept Stat Santiago 7820436 Chile Pontificia Univ Catolica Chile MiDaS Ctr Discovery Struct Complex Data Santiago 7820436 Chile Pontificia Univ Catolica Chile Dept Comp Sci Santiago 7820436 Chile

Motivated by the implementation of a SARS-Cov-2 sewer surveillance system in Chile during the COVID-19 pandemic, we propose a set of mathematical and algorithmic tools that aim to identify the location of an outbreak under uncertainty in the network structure. Given an upper bound on the number of samples we can take on any given day, our framework allows us to detect an unknown infected node by adaptively sampling different network nodes on different days. Crucially, despite the uncertainty of the network, the method allows univocal detection of the infected node, albeit at an extra cost in time. This framework relies on a specific and well-chosen strategy that defines new nodes to test sequentially, with a heuristic that balances the granularity of the information obtained from the samples. We extensively tested our model in real and synthetic networks, showing that the uncertainty of the underlying graph only incurs a limited increase in the number of iterations, indicating that the methodology is applicable in practice.

关键词： wastewater-based epidemiology public health surveillance systems robust algorithms search in uncertain trees

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VoiScan: Telephone Voice Analysis for Health and Biometric Applications 19th

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19th International Conference on Speech and Computer (SPECOM)

作者： Baghai-Ravary, Ladan Beet, Steve W. Aculab Plc Bramley Rd Milton Keynes MK1 1PT Bucks England

ISBN: (纸本)9783319664286;9783319664293

The telephone, whether mobile, landline, or VoIP, is probably the most widely used form of long-distance communication. The most common use of voice biometrics is in telephone-based speaker verification, so the ability to operate effectively over the telephone is crucial. Similarly, access to vocal health monitoring, and other voice analysis technology, would benefit enormously if it were available over the telephone, via an automatic system. This paper describes a set of voice analysis algorithms, designed to be robust against the kinds of distortion and signal degradation encountered in modern telephone communication. The basis of the algorithms in traditional analysis is discussed, as are the design choices made in order to ensure robustness. The utility of these algorithms is demonstrated in a number of target domains.

关键词： Voice analysis robust algorithms Tele-health voice analysis Voice bio-markers Voice biometrics Telephone speaker verification

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Stability number of bull- and chair-free graphs revisited

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DISCRETE APPLIED MATHEMATICS 2003年第1期131卷 39-50页

作者： Brandstädt, A Hoàng, CT Le, VB Univ Rostock Fachbereich Informat D-18051 Rostock Germany Wilfrid Laurier Univ Dept Phys & Comp Waterloo ON N2L 3C5 Canada

De Simone showed that prime bull- and chair-free graphs containing a co-diamond are either bipartite or an induced cycle of odd length at least five. Based on this result, we give a complete structural characterization of prime (bull,chair)-free graphs having stability number at least four as well as of (bull,chair,co-chair)-free graphs. This implies constant-bounded clique width for these graph classes which leads to linear time algorithms for some algorithmic problems. Moreover, we obtain a robust O(nm) time algorithm for the maximum weight stable set problem on bull- and chair-free graphs without testing whether the (arbitrary) input graph is bull- and chair-free. This improves previous results with respect to structural insight, robustness and time bounds. (C) 2003 Elsevier B.V. All rights reserved.

关键词： modular decomposition prime graphs maximum weight stable set problem on graphs Bull- and chair-free graphs robust algorithms clique width of graphs

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Optimal and robust Methods for Unconditional Optimization

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IFAC Proceedings Volumes 1981年第2期14卷 519-523页

作者： B.T. Poljak Ya.Z. Tsypkin Institute for Control Science Moscow USSR

The asymptotic convergence rate of iterative algorithms for unconditional optimization in the presence of random noise is studied. The optimal algorithm is found, which maximaze the rate of convergence. The algorithm involves the nonlinear transformation of the gradient; the form of the transformation depends on the density of the noise. To find the best algorithm in the situation when the density is unknown we apply robust estimation ideology. We provide the algorithm which is asimptotically minimax for the specified class of densities. Some examples of the optimal and robust algorithms are presented. The numerical experiments verify the theoretical conclusions; they also demonstrate the difference between the asymptotic and nonasymptotic behavior of the algorithms in some cases.

关键词： Optimization mathematical programming adaptive systems stochastic systems convergence of numerical methods iterative methods robust algorithms gradient technique

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Information Elicitation from Rowdy Crowds 21

Information Elicitation from Rowdy Crowds

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30th World Wide Web Conference (WWW)

作者： Schoenebeck, Grant Yu, Fang-Yi Zhang, Yichi Univ Michigan Ann Arbor MI 48109 USA Harvard Univ Boston MA 02115 USA

ISBN: (纸本)9781450383127

We initiate the study of information elicitation mechanisms for a crowd containing both self-interested agents, who respond to incentives, and adversarial agents, who may collude to disrupt the system. Our mechanisms work in the peer prediction setting where ground truth need not be accessible to the mechanism or even exist. We provide a meta-mechanism that reduces the design of peer prediction mechanisms to a related robust learning problem. The resulting mechanisms are epsilon-informed truthful, which means truth-telling is the highest paid epsilon-Bayesian Nash equilibrium (up to epsilon-error) and pays strictly more than uninformative equilibria. The value of epsilon depends on the properties of robust learning algorithm, and typically limits to 0 as the number of tasks and agents increase. We show how to use our meta-mechanism to design mechanisms with provable guarantees in two important crowdsourcing settings even when some agents are self-interested and others are adversarial.

关键词： information elicitation crowdscourcing robust algorithms

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Learning a statistical 3D geometric head model

Learning a statistical 3D geometric head model

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Conference on Videometrics VII

作者： Lai, SH Chen, YL Natl Tsing Hua Univ Dept Comp Sci Hsinchu 300 Taiwan

ISBN: (纸本)0819448133

Statistical modeling of signal/image data has been used extensively for recognition and estimation. Principal component analysis was very popular for the statistical signal modeling and analysis. In this paper, we present a system to build a 3D statistical head model from incomplete data. In this system, we first transformed the 3D head scan data points into a cylindrical coordinate to obtain 2D surface maps. After these 2D surface maps were aligned, we computed the associated mean vector and covariance matrix. Then, the principal component analysis technique was applied to compute the principal components and the corresponding eigenvalues of the covariance matrix. Experimental results are given to show the 3D head shape variations from the computed 3D statistical model.

关键词： statistical head model point distribution models principal component analysis surface registration robust algorithms missing data

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Detecting and tracking dynamic objects in complex environments

Detecting and tracking dynamic objects in complex environmen...

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International Symposium on Multispectral Image Processing and Pattern Recognition

作者： Zhou, LX Liu, JL Gu, WK Zhejiang Univ Dept Informat Sci & Elect Engn Hangzhou 310027 Peoples R China

ISBN: (纸本)0819430064

This paper presents a robust algorithm for detecting and tracking multiple targets in a long video sequence. What differentiate it from previous approaches are the complex environments, the unconstrained camera motion, as well as the comparatively short distance between the sensor and the targets. Firstly the background motion is estimated by a global LMedS algorithm, then on the compensated difference image a graph-like stochastic procedure is applied for tracking multiple moving objects. Real video experiments show its efficiency.

关键词： ATR motion compensation real-time tracking robust algorithms

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MapSnapper: Engineering an efficient algorithm for matching images of maps from mobile phones

MapSnapper: Engineering an efficient algorithm for matching ...

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Conference on Multimedia Content Access - algorithms and Systems II

作者： Hare, Jonathon S. Lewis, Paul H. Gordon, Layla Hart, Glen Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England Ordnance Survey Southampton SO16 4GU Hants England

ISBN: (纸本)9780819469922

The MapSnapper project aimed to develop a system for robust matching of low-quality images of a paper map taken from a mobile phone against a high quality digital raster representation of the same map. The paper presents. a novel methodology for performing content-based image retrieval and object recognition from query images that have been degraded by noise and subjected to, transformations through the imaging system. In addition the paper also provides an insight into the evaluation-driven development process that was used to incrementally improve the matching performance until the design specifications were met.

关键词： image matching mobile device interest points salient regions local descriptors geometric matching constraints robust algorithms

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Low Rank Approximation with Entrywise l₁-Norm Error 2017

Low Rank Approximation with Entrywise <i>l</i><sub>1</sub>-N...

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49th Annual ACM-SIGACT Symposium on Theory of Computing (STOC)

作者： Song, Zhao Woodruff, David P. Zhong, Peilin Univ Texas Austin Dept Comp Sci Austin TX 78712 USA IBM Almaden Res Ctr San Jose CA 95120 USA Columbia Univ Dept Comp Sci New York NY 10027 USA

ISBN: (纸本)9781450345286

We study the l(1)-low rank approximation problem, where for a given n x d matrix A and approximation factor alpha >= 1, the goal is to output a rank-k matrix (A) over cap for which parallel to A - (A) over cap parallel to(1) <= alpha. min (rank-k matrices A') parallel to A - A'parallel to(1), where for an n x d matrix C, we let parallel to C parallel to(1) = Sigma(n)(i=1) Sigma(d)(j=1) vertical bar C-i,C- j vertical bar . This error measure is known to be more robust than the Frobenius norm in the presence of outliers and is indicated in models where Gaussian assumptions on the noise may not apply. The problem was shown to be NP-hard by Gillis and Vavasis and a number of heuristics have been proposed. It was asked in multiple places if there are any approximation algorithms. We give the first provable approximation algorithms for l(1)-low rank approximation, showing that it is possible to achieve approximation factor alpha = (log d) . poly(k) in nnz(A) + (n + d) poly(k) time, where nnz(A) denotes the number of non-zero entries of A. If k is constant, we further improve the approximation ratio to O(1) with a poly(nd)-time algorithm. Under the Exponential Time Hypothesis, we show there is no poly(nd)-time algorithm achieving a (1 + 1/log(1+gamma) (nd))-approximation, for gamma > 0 an arbitrarily small constant, even when k = 1. We give a number of additional results for l(1)-low rank approximation: nearly tight upper and lower bounds for column subset selection, CUR decompositions, extensions to low rank approximation with respect to l(p)-norms for 1 <= p < 2 and earthmover distance, low-communication distributed protocols and low-memory streaming algorithms, algorithms with limited randomness, and bicriteria algorithms. We also give a preliminary empirical evaluation.

关键词： Entry-wise l(1) norm low rank approximation robust algorithms sketching numerical linear algebra

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