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Iranian Conference of Biomedical engineering

作者： Maryam Afzali Emad Fatemizadeh Hamid Soltanian-Zadeh Department of Electrical Engineering Biomedical Signal and Image Processing Laboratory(BiSIPL) Sharif University of Technology Tehran Iran Control and Intelligent Processing Center of Excellence(CIPCE) School of Electrical and Computer Engineering University of Tehran Tehran Iran & Image Analysis Laboratory Radiology Department Henry Ford Health System Detroit Michigan USA

ISBN: (纸本)9781467331289

Diffusion tensor magnetic resonance imaging (DTMRI) is a non-invasive method for investigating the brain white matter structure. It can be used to evaluate fiber bundles in the brain but in the regions with crossing fibers, it fails. To resolve this problem, high angular resolution diffusion imaging (HARDI) with a large number of diffusion encoding directions is used and for reconstruction, the Q-ball method is applied. In this method, orientation distribution function (ODF) of fibers can be calculated. Mathematical models play a crucial role in the field of ODF. For instance, in registering Q-ball images for applications like group analysis or atlas construction, one needs to interpolate ODFs. To this end, principal diffusion directions (PDDs) of each ODF are needed. In this paper, PDDs are defined as vectors that connect the corresponding local maxima of ODF values. Then, ODFs are interpolated using PDDs. The proposed method is evaluated and compared with previous protocols. Experimental results show that the proposed interpolation algorithm preserves the principal direction of fiber tracts without producing any deviations in the tracts. It is shown that changes in the entropy of the interpolated ODFs are almost linear and the bloating effect (blurring of the principal directions) can be removed.

关键词： High angular resolution diffusion imaging (HARDI) Q-ball imaging Orientation distribution function (ODF) Interpolation Principal diffusion direction (PDD)

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A review on low-complexity structures and algorithms for the correction of mismatch errors in time-interleaved ADCs

A review on low-complexity structures and algorithms for the...

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Annual IEEE Northeast Workshop on Circuits and Systems (NEWCAS)

作者： Christian Vogel Matthias Hotz Shahzad Saleem Katharina Hausmair Michael Soudan FTW Telecommunications Research Center Vienna Vienna Austria Department of Electrical Engineering National University of Computer and Emerging Sciences Islamabad Pakistan Signal Processing and Speech Communication Laboratory Graz University of Technology Graz Austria

In this paper we review the progress in the design of low-complexity digital correction structures and algorithms for time-interleaved ADCs over the last five years. We devise a discrete-time model, state the design problem, and finally derive the algorithms and structures. In particular, we discuss efficient algorithms to design time-varying correction filters as well as iterative structures utilizing polynomial based filters. Finally, we give an outlook to future research questions.

关键词： Circuits and systems Complexity theory Algorithm design and analysis Calibration Time varying systems Polynomials Time frequency analysis

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Using simple relays to improve physical-layer security

Using simple relays to improve physical-layer security

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IEEE International Conference on Communications in China (ICCC)

作者： Gan Zheng Jiangyuan Li Kai-Kit Wong Athina P. Petropulu Björn Ottersten Interdisciplinary Centre for Security Reliability and Trust (SnT) University of Luxembourg Luxembourg Department of Electrical and Computer Engineering Rutgers The State University of New Jersey USA Department of Electronic and Electrical Engineering University College London London UK Signal Processing Laboratory ACCESS Linnaeus Center KTH Royal Institute of Technology Sweden

This paper studies different uses of two cooperating relays to improve the secrecy rate of a wiretap channel. These two relays are assumed to perform only simple functions: either amplify-and-forward (AF) or jamming. Complex functions such as decode-and-forward (DF) are not considered. We study three modes of cooperation: i) cooperative jamming (CJ), ii) AF-aided beamforming and iii) mixed AF-aided beamforming and CJ, all with individual relay power constraints. While i) is known in the literature, our efforts are spent on ii) and iii). In particular, for iii), we assume that the jamming signals in two communication stages are correlated, giving rise to improved performances. We also propose a heuristic approach for selecting the appropriate cooperating mode. Simulation results illustrate the performance gain of each scheme under different channel conditions and the effectiveness of the proposed mode selection method.

关键词： Relays Jamming Interference Security Protocols Noise Physical layer

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Generalized geometry-based optimal power control in wireless networks

Generalized geometry-based optimal power control in wireless...

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IEEE Communications Society Conference on Sensor and Ad Hoc Communications and Networks (SECON)

作者： Wei Wang Kang G. Shin Zhaoyang Zhang Wenbo Wang Tao Peng Department of Information Science and Electronic Engineering Zhejiang Provincial Key Laboratory of Information Network Technology University of Zhejiang Hangzhou China Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA Wireless Signal Processing and Networking Laboratory Beijing University of Posts and Telecommunications Beijing China

Geometry-based optimal power control was proposed in [14] to transform the power-control problem to a new geometrical problem on the position relationship between a line and some points. This scheme provides a novel visual perspective and lowers the complexity of optimization. We generalize this scheme to a larger class of power-control optimization problems so as to maximize the network utility with multiple average and peak power constraints in wireless networks. To facilitate the handling of the geometrical model, we define a subset of geometrical models with specified characteristics, called a regular geometrical model, and derive the type of power-control problems eligible for the regular geometrical model. For such a type of problems, two strategies are proposed for the construction of the regular geometrical model. Utilizing geometrical properties, we propose a novel geometry-based optimization scheme for the general power-control problem. Its computational complexity is significantly lower than the conventional algorithms. We also provide a further discussion on irregular geometrical model cases. Finally, we provide two examples of deploying the proposed geometry-based power-control scheme.

关键词： Optimization Silicon Computational modeling Interference Complexity theory Power control Wireless networks

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A model-based method with joint sparsity constraint for direct diffusion tensor estimation

A model-based method with joint sparsity constraint for dire...

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IEEE International Symposium on Biomedical Imaging

作者： Yanjie Zhu Yin Wu Yuanjie Zheng Ed X. Wu Leslie Ying Dong Liang Paul C. Lauterbur Research Centre for Biomedical Imaging Shenzhen Institutes of Advanced Technology Key Laboratory of Health Informatics Chinese Academy of Sciences Shenzhen China Department of Radiology University of Pennsylvania PA USA Laboratory of Biomedical Imaging and Signal Processing Department of Electrical and Electronic Engineering University of Hong Kong Pokfulam Hong Kong China Department of Electrical Engineering and Computer Science University of Wisconsin Milwaukee Milwaukee WI USA

Diffusion tensor imaging (DTI) has been widely used for nondestructive characterization of microstructures of myocardium or brain connectivity. It requires repeated acquisition with different diffusion gradients. The long acquisition time greatly limits the clinical application of DTI. In this paper, a novel method, named model-based method with joint sparsity constraint (MB-JSC), effectively incorporates the prior information on the joint sparsity of different diffusion-weighted images in direct estimation of the diffusion tensor from highly undersampled k-space data. Experimental results demonstrate that the proposed method is able to estimate the diffusion tensors more accurately than the existing method when a high net reduction factor is used.

关键词： Tensile stress Diffusion tensor imaging Image reconstruction Joints Compressed sensing Biological system modeling

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Erratum (“A State-Space Analysis for Reconstruction of Goal-Directed Movements Using Neural signals” Neural Computation, Volume 18, Number 10, pp. 2465–2494)

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Neural Computation 2012年第4期24卷 1106-1107页

作者： Iahn Cajigas Lakshminarayan Srinivasan Neuroscience Statistics Research Laboratory Department of Anesthesia and Critical Care Massachusetts General Hospital Charlestown MA 02129 U.S.A. Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 U.S.A. and Division of Health Sciences and Technology Massachusetts Institute of Technology Cambridge MA 02139 U.S.A. Neural Signal Processing Laboratory Department of Radiology David Geffen School of Medicine University of California Los Angeles CA 90095 U.S.A.

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Physics of propagation in a cellular wireless communication environment

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URSI Radio Science Bulletin 2012年第343期2012卷 5-21页

作者： Tapan K. Sarkar W. Dyab M. N. Abdallah M. Salazar-Palma M. V. S. N. Prasad S. Barbin S. Weng Ting Department of Electrical Engineering and Computer Science Syracuse University Syracuse New York 13244-1240 USA Dept. of Signal Theory & Communications Universidad Carlos Hide Madrid Avenidade la Universidad 30 28911 Leganes Madrid Spain National Physical Laboratory Dr. K. S. Krishnan Road New Delhi-110012 India Departamento de Engenharia de Telecomunicações e Controle Escola Politécnica da Universidade de São Paulo São Paulo Brazil Department of Electrical Engineering and Computer Science University of Macau Av. Padre Tomas Pereira Taipa Macau China (CIE)

The objective of this paper is to illustrate from a physics standpoint the nature of the fields that carry energy from a transmitter to a receiver located over an imperfectly conducting Earth. In an accompanying paper [1], it was shown from both the theoretical (developed from the classical Sommerfeld attenuation function) and experimental points of view that the fields inside a cellular-communication cell decay as 30 dB per decade, following a slow fading region. The 30 dB per decade region is followed by a region (in the fringe area) where the rate of decay is 40 dB per decade. This means that the fields decay as 1/ρ 1.5 (where ρ is the radial distance between the transmitter and the receiver) and 1/ρ 2 , respectively inside a cell. The first goal is to illustrate that Sommerfeld had no error in sign in his classic 1909 paper. However, while computing his asymptotic development of the branch-cut integral, Sommerfeld did not notice that beside the space wave, this contains the surface wave with a negative sign, which would cancel the residue of the pole. In other words, no surface wave can be generated from a pole that is a part of the original Sommerfeld solution for radiation from a dipole operating over an imperfectly conducting ground. Other type of waves, e.g., Norton's surface wave and a radiation field that decays as 1/ρ 15 , are part of the ground wave. They can be derived from the same Sommerfeld attenuation function, but using different types of approximations. As already mentioned, Norton's surface wave and the radiation field (decaying as 1/ρ 1.5 ) are a part of the solution. These points were illustrated in an accompanying paper [1]: here, we focus on the physics of these waves. We also explain what the mathematical characteristics of a surface wave are, as there is a lot of confusion in the usage of the same word for different types of waves. The goal of this paper is hence to develop an understanding of the physics associated with radiating fields t

关键词： Surface waves Earth Electronic mail Electromagnetic scattering Antennas Propagation constant

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A higher radix FFT FPGA implementation suitable for OFDM systems

A higher radix FFT FPGA implementation suitable for OFDM sys...

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2011 18th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2011

作者： Jaber, Marwan A. Massicotte, Daniel Achouri, Youssef Université du Québec à Trois-Rivières Electrical and Computer Engineering Department Laboratory of Signal and System Integrations Canada

ISBN: (纸本)9781457718458

This article describes a new approach for higher radix butterflies suitable for pipeline implementation. Based on the butterfly computation introduced by Cooley-Tukey [1], we will introduce a novel approach for the Discrete Fourier Transform (DFT) factorization, by redefining the butterfly computation, which is more suitable for efficient VLSI implementation. The proposed factorization motivated us to present a new concept of a radix-r Fast Fourier Transform (FFT), in which the radix-r butterfly computation concept was formulated as composite engines to implement each of the butterfly computations. This concept enables the radix r butterfly-processing element (BPE) to be designed by maintaining only one complex value multiplier in the butterfly critical path for any given r [2]. Algorithmic description and performance of low complexity FFT methods are considered in this paper where the speed and accuracy evaluation of the proposed method in fixed point is also elaborated. © 2011 IEEE.

关键词： Factorization

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics): Preface

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2012年 7191 LNCS卷 V-VII页

作者： Cichocki, Andrzej Theis, Fabian Yeredor, Arie Zibulevsky, Michael Helmholtz Center Munich Institute of Bioinformatics and Systems Biology Ingolstädter Landstr. 1 85764 Neuherberg Germany Riken Brain Science Institute Laboratory for Advanced Brain Signal Processing 2-1 Hirosawa Wako-shi 351-0198 Saitama Japan Tel-Aviv University School of Electrical Engineering Tel-Aviv 69978 Israel Technion - Israel Institute of Technology Department of Computer Science Haifa 32000 Israel

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Resilient subclass discriminant analysis with application to prelens tear film interferometry

Resilient subclass discriminant analysis with application to...

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Lecture Notes in computer Science

作者： Boyer, Kim L. Wu, Dijia Signal Analysis and Machine Perception Laboratory Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY United States Siemens Corporate Research Princeton NJ United States

ISBN: (纸本)9783642215865

The study of tear film thickness and breakup has important implications for understanding tear physiology and dynamics. We have developed a complete end-to-end automated system for robust and accurate measurements of the tear film thickness from interferometric video as a function of position and time (following a blink). This paper will primarily address the problem of identifying dry regions on the surface of the contact lens, which is one of the four major components of the system. (The others are motion stabilization, image normalization, and phase demodulation to infer absolute thickness and map the surface. To address the challenging wet/dry segmentation problem, we propose a new Gaussian clustering method for feature extraction in high dimensional spaces. Each class is modeled as a mixture of Gaussians, clustered using Expectation-Maximization in the lower-dimensional Fisher's discriminant space. We show that this approach adapts to a wide range of distributions and is insensitive to training sample size. We present experimental results on the real-world problem of identifying regions of breakup (drying) of the prelens tear film from narrowband interferometry for contact lens wearers in vivo. © 2011 Springer-Verlag Berlin Heidelberg.

关键词： Feature extraction

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