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Random-walk-based stochastic modeling of three-dimensional fiber systems

Physical Review E 2011年第4期83卷 041804-041804页

作者： Hellen Altendorf Dominique Jeulin Department of Image Processing Fraunhofer Institute of Industrial Mathematics Fraunhofer-Platz 1 D-67663 Kaiserslautern Germany Center of Mathematical Morphology Mines Paris Tech 35 rue Saint Honoré F-77305 Fontainebleau Cedex France

For the simulation of fiber systems, there exist several stochastic models: systems of straight nonoverlapping fibers, systems of overlapping bending fibers, or fiber systems created by sedimentation. However, there is a lack of models providing dense, nonoverlapping fiber systems with a given random orientation distribution and a controllable level of bending. We introduce a new stochastic model in this paper that generalizes the force-biased packing approach to fibers represented as chains of balls. The starting configuration is modeled using random walks, where two parameters in the multivariate von Mises–Fisher orientation distribution control the bending. The points of the random walk are associated with a radius and the current orientation. The resulting chains of balls are interpreted as fibers. The final fiber configuration is obtained as an equilibrium between repulsion forces avoiding crossing fibers and recover forces ensuring the fiber structure. This approach provides high volume fractions up to 72.0075%.

关键词： STOCHASTIC processes STOCHASTIC analysis MULTIVARIATE analysis DISTRIBUTION (Probability theory) EQUILIBRIUM

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Sampling step importance in hierarchical semantic segmentation of microscopic images

Sampling step importance in hierarchical semantic segmentati...

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International Conference on System Theory, Control, and Computing (ICSTCC)

作者： Cristian Smochina Vasile Manta Walter Kropatsch Department of Computer Science and Engineering Gheorghe Asachi Technical University of Iasi Romania Pattern Recognition and Image Processing Group Institute of Computer Graphics and Algorithms Vienna University of Technology Austria

The objective of semantic segmentation in microscopic images is to extract the cellular, nuclear or tissue components. This problem is challenging due to the large variations of these components features (size, shape, orientation or texture). In this paper we improve the technique presented in [17] used to identify the epithelial nuclei (crypt) against interstitial nuclei in microscopic images taken from colon tissues. In the proposed enhanced approach, the crypt inner boundary is detected using the closing morphological pyramid instead of morphological hierarchy. The outer crypt border is determined by the epithelial nuclei, overlapped by the maximal isoline of the inner boundary. The use of sampling in building the pyramid offers computational efficiency, reduces the amount of used memory, increase the robustness and preserve the quality results. An analysis of the two approaches is performed considering the number of pixels processed to create each level. Also the relation between the levels of the hierarchical structures is established.

关键词： Cryptography image segmentation image reconstruction image resolution Microscopy Buildings Shape

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Mass-preserving motion correction of dual gated cardiac PET

Mass-preserving motion correction of dual gated cardiac PET

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Fabian Gigengack Lars Ruthotto Martin Burger Carsten H. Wolters Xiaoyi Jiang Klaus P. Schäfers European Institute for Molecular Imaging (EIMI) and the Department of Mathematics and Computer Science University of Münster Germany Institute of Mathematics and Image Computing (MIC) University of Lübeck Germany Institute for Computational and Applied Mathematics University of Münster Germany Institute for Biomagnetism and Biosignalanalysis University of Münster Germany Department of Mathematics and Computer Science University of Münster Germany

image degradation due to motion is a known problem in Positron Emission Tomography (PET). To reduce motion artifacts in PET, gating based techniques were found applicable. In pure respiratory gated PET, each gate still contains cardiac motion. Analogously, pure cardiac gated PET images still contain respiratory motion. Hence, we make use of dual (joint respiratory and cardiac) gating to further reduce the amount of motion contained in the images. The inclusion of non-rigid cardiac motion leads to intensity modulations caused by the Partial Volume Effect (PVE). To overcome the intensity modulations we identified and considered the mass-preserving property of PET images in the Variational Algorithm for Mass-Preserving image REgistration (VAMPIRE). The aim of this paper is the elimination of both cardiac and respiratory motion in thoracic dual gated PET without a loss of statistic. The strategy of our proposed motion correction approach is: 1) Dual gating, 2) Mass-preserving motion estimation (VAMPIRE), and 3) Averaging of the aligned images. In a patient study we showed that the proposed mass-preserving motion correction strategy significantly removes motion artifacts in cardiac PET. VAMPIRE achieved accurate results that resemble cardiac and respiratory motion across all patients.

关键词： Argon Logic gates Robustness Positrons Positron emission tomography

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Guest Editorial: Vehicular communications and networks - Part I

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IEEE Journal on Selected Areas in Communications 2011年第1期29卷 1-6页

作者： Wang, Cheng-Xiang Vasilakos, Athanasios V. Murch, Ross D. Stüber, Gordon Shen, Xuemin Sherman Chen, Wai Kosch, Timo Joint Research Institute for Signal and Image Processing School of Engineering and Physical Sciences Heriot-Watt University Edinburgh EH14 4AS United Kingdom Dept. of Computer and Telecommunications Engineering University of Western Macedonia Kozani 50100 Greece Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA 30332-0250 United States Department of Electrical and Computer Engineering University of Waterloo Waterloo ON N2L 3G1 Canada Applied Research Telcordia Technologies Inc. Piscataway NJ 07054 United States BMW Group Research and Technology Hanauer Strasse 46 D-80992 Munich Germany

Part I of this special issue is devoted to the physical layer, MAC layer, and physical-link cross-layer design technologies of vehicular communications and networks. There are 21 papers in this issue.

关键词： Communication Research iodine VEHICULAR COMMUNICATIONS

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Noise benefits in the expectation-maximization algorithm: Nem theorems and models

Noise benefits in the expectation-maximization algorithm: Ne...

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International Joint Conference on Neural Networks (IJCNN)

作者： Osonde Osoba Sanya Mitaim Bart Kosko Department of Electrical Signal and Image Processing Institute University of Southern California Los Angeles CA USA Department of Electrical and Computer Engineering Faculty of Engineering Thammasat University Pathumthani Thailand

We prove a general sufficient condition for a noise benefit in the expectation-maximization (EM) algorithm. Additive noise speeds the average convergence of the EM algorithm to a local maximum of the likelihood surface when the noise condition holds. The sufficient condition states when additive noise makes the signal more probable on average. The performance measure is Kullback relative entropy. A Gaussian-mixture problem demonstrates the EM noise benefit. Corollary results give other special cases when noise improves performance in the EM algorithm.

关键词： Noise Random variables Stochastic resonance Probability density function Noise measurement Maximum likelihood estimation Signal processing algorithms

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Robust control for a class of Markov switched linear systems with linear fractional uncertainties

Robust control for a class of Markov switched linear systems...

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作者： Huang, Hongmei Long, Fei Fu, Pengwei Institute of Intelligent Information Processing Guizhou University Huaxi Guiyang 550025 China College of Computer Science and Information Guizhou University Huaxi Guiyang Guizhou 550025 China Department of Mathematics College of Science Guizhou University Huaxi Guiyang Guizhou 550025 China

ISBN: (纸本)9789881725592

The robust control problem for a class of continuous-time Markov switched linear systems with Wiener process disturbance with linear fractional uncertainties via switched state feedback and switched dynamic output feedback is investigated, respectively. Our attention is focused on the design of state feedback controllers and dynamic output feedback controllers so that the whole close-loop system is robust stochastic stabilization based on multiple Lyapunov function and LMI approach. Finally, two numerical examples are presented to illustrate the effectiveness of the obtained theoretical results. © 2011 Chinese Assoc of Automation.

关键词： State feedback

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COSPARSE ANALYSIS MODELING - UNIQUENESS AND ALGORITHMS

COSPARSE ANALYSIS MODELING - UNIQUENESS AND ALGORITHMS

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IEEE International Conference on Acoustics, Speech and Signal processing

作者： Sangnam Nam Michael E. Davies Michael Elad Remi Gribonval IRISA INRIA Rennes Bretagne Atlantique France IDCOM & Joint Research Institute of Signal and Image Processing Edinburgh University UK Department of Computer Science Technion-Israel Institute of Technology Israel

In the past decade there has been a great interest in a synthesis-based model for signals, based on sparse and redundant representations. Such a model assumes that the signal of interest can be composed as a linear combination of few columns from a given matrix (the dictionary). An alternative analysis-based model can be envisioned, where an analysis operator multiplies the signal, leading to a cosparse outcome. In this paper, we consider this analysis model, in the context of a generic missing data problem (e.g., compressed sensing, inpainting, source separation, etc.). Our work proposes a uniqueness result for the solution of this problem, based on properties of the analysis operator and the measurement matrix. This paper also considers two pursuit algorithms for solving the missing data problem, an L1-based and a new greedy method. Our simulations demonstrate the appeal of the analysis model, and the success of the pursuit techniques presented.

关键词： Analytical models Data models Algorithm design and analysis Matching pursuit algorithms Optimization Dictionaries Computational modeling

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ICIC Express Letters 2011年第3期5卷 727-731页

作者： Li, Li Zhang, David Ruan, Liuzhao Institute of Computer Graphics and Image Processing Hangzhou Dianzi University Second Avenue Xiashagaojiao District Hangzhou 310018 China Centre for Multimedia Signal Processing and Department of Computing Biometrics Research Centre Hong Kong Polytechnic University Hung Horn Kowloon Hong Kong

The popular formulas of evaluating the similarity of digital watermarks have serious drawbacks: when the similarity degree is 1, the watermarks are not unique. This paper firstly analyzes the drawbacks in the popular formulas, then proposes a new similarity degree formula, which weakens the shortcomings of the existing formulas and overcomes the lack of uniqueness in theory. From the experimental results, the new formula not only does well in evaluating the watermark's similarity degree, but also is in good accordance with visual perception. © 2011 ISSN 1881-803X.

关键词： Digital watermarking

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Triply fuzzy function approximation for Bayesian inference

Triply fuzzy function approximation for Bayesian inference

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International Joint Conference on Neural Networks (IJCNN)

作者： Osonde Osoba Sanya Mitaim Bart Kosko Department of Electrical Engineering Signal and Image Processing Institute University of Southern California Los Angeles CA USA Department of Electrical and Computer Engineering Faculty of Engineering Thammasat University Pathumthani Thailand

We prove that independent fuzzy systems can uniformly approximate Bayesian posterior probability density functions by approximating prior and likelihood probability densities as well as hyperprior probability densities that underly priors. This triply fuzzy function approximation extends the recent theorem for uniformly approximating the posterior density by approximating just the prior and likelihood densities. This allows users to state priors and hyper-priors in words or rules as well as to adapt them from sample data. A fuzzy system with just two rules can exactly represent common closed-form probability densities so long as they are bounded. The function approximators can also be neural networks or any other type of uniform function approximator.

关键词： Function approximation Fuzzy systems Bayesian methods Additives Fuzzy sets Joints

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Cross-Layer Interference Mitigation for Cognitive Radio MIMO Systems

Cross-Layer Interference Mitigation for Cognitive Radio MIMO...

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IEEE International Conference on Communications (ICC)

作者： Zengmao Chen Cheng-Xiang Wang Xuemin Hong John Thompson Sergiy A. Vorobyov Dongfeng Yuan Joint Research Institute of Signal and Image Processing Heriot-Watt University Edinburgh UK Joint Research Institute of Signal and Image Processing University of Edinburgh Edinburgh UK Department of Electrical and Computer Engineering University of Alberta Edmonton AB Canada School of Information Science and Engineering Shandong University Jinan Shandong China

In this paper, we investigate the interference mitigation from a cross-layer perspective for a cognitive radio (CR) multiple-input multiple-output (MIMO) network coexisting with a primary time-division-duplexing (TDD) system. The channel allocation in the media access control (MAC) layer and a subspace-based precoding scheme in the physical layer of the CR network are jointly considered to minimise the interference to the primary user and maximise the CR throughput. Two distributed cross-layer algorithms, namely, joint iterative channel allocation and precoding (JICAP) and non-iterative channel allocation and precoding (NICAP), are proposed for the cases with and without channel information among CR nodes, respectively. Moreover, a channel estimation scheme is also proposed to enable the NICAP. The effectiveness of the proposed algorithms over non-cross-layer counterpart is demonstrated via simulations.

关键词： Channel allocation Downlink Interference channels Channel estimation Covariance matrix Physical layer

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