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Microwaves, Radar and Remote Sensing Symposium, MRRS

作者： Jiabing Zhu Yi Hong Liang Tao East China Research Institute of Electronic Engineering Hefei Anhui China Education Ministry Key Laboratory of Intelligent Computing and Signal Processing Anhui University China

Standard backprojection technique is used in typical through-wall synthetic aperture radar (TWSAR) image, it implicitly assumes infinite beamwidth, whereby the entire target area is illuminated and returns are collected from all points in the imaging grid, and this decreases the efficiency of the algorithm by summing over unnecessary grid points. In order to eliminate the disadvantage, the time-domain backprojection method based on finite beamwidth processing is proposed in the paper. The processing method is designed to be more physically realistic by accounting for the actual antenna pattern. Simulation results show that depending on the width of the effective beam, the number of processing loops can be reduced by up to 50%, while still maintaining good image quality in terms of the reconstructed target response.

关键词： Radar imaging Apertures Imaging Finite element methods signal processing algorithms

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Study of millimetre-wave generation based on optical frequency multiplication

Study of millimetre-wave generation based on optical frequen...

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IET International Communication Conference on Wireless Mobile and computing, CCWMC 2011

作者： Ding, Yan Zhu, Jun Fang, Wei-Dong Ge, Xiao-Guang Chen, Xiang Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University No.3 Feixi Rd Hefei Anhui 230039 China Shanghai Research Center for Wireless Communications Information Building 1 lane 280 Linhong Rd China Shanghai University No. 149 Yanchang Rd Shanghai 200072 China

ISBN: (纸本)9781849195058

To meet the increasing capacity and mobility as well as decrease the costs in next-generation optical access networks, RoF technology is a promising technique in the emerging optical and wireless convergence network, mm-wave generation is a key technique to realize the convergence network. In this paper, existing optical mm-wave generation technologies are introduced, including direct modulation, optical heterodyning and external modulation. Associated with Shanghai University, a scheme based on Optical Frequency Multiplication employing a dual drive Mach-Zehnder Modulator (DD-MZM) is presented. The novel efficient technique does not require expensive high-frequency electrical equipment. Moreover, no optical filtering is used, which significantly reduces the cost.

关键词： Millimeter waves

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A novel description of the reproducing kernel support vector machines

A novel description of the reproducing kernel support vector...

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IEEE International Conference on Computer Science and Automation Engineering (CSAE)

作者： Li-xiang Xu Bin Luo Feng-hai Yu Jin Xie Department of Mathematics & Physics Hefei University Hefei China Key Laboratory of Intelligent Computing & Signal Processing of Ministry of Education School of Computer Science and Technology Anhui University Anhui China

Support vector machines (SVMs) and related kernel-based algorithms have become one of the most popular approaches for many machine learning problems. but little is known about the structure of their reproducing kernel Hilbert spaces (RKHS). In this work, based on Mercer's Theorem, the relation among reproducing kernel (RK) and Mercer kernel, and their roles in SVMs are discussed, corresponding to some important theorems and consequences are given. Furthermore, a novel framework of reproducing kernel support vector machines (RKSVM) is proposed. The simulation results are presented to illustrate the feasibility of the proposed method. Choosing a proper Mercer kernel for different tasks is an important factor for studying the result of the SVMs.

关键词： Kernel Support vector machines Hilbert space Equations Mathematical model Resonant frequency Simulation

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MST based stream data clustering algorithm

International Journal of Digital Content Technology and its ...

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International Journal of Digital Content Technology and its Applications 2011年第9期5卷 352-360页

作者： Cheng, Zheng Xiaodong, Zhu Jingcheng, Li Key Laboratory of Intelligent Computing and Signal Processing of the Ministry of Education Anhui University China School of Computer Science and Technology Anhui University China Institute of Information Management and Electronic Business University of Shanghai for Science and Technology China

How to make use of limited memory space and processing speeds of computer for rapid and accurate data mining has become an important research topic on the stream data cluster analysis. A stream data clustering algorithm based on the minimum spanning tree (MSTSC) is described. MSTSC is divided into online processing and offline clustering. Stream data are analyzed online by using two groups of processing unit respectively. In offline process clusters is taken as representative objects, and the minimum spanning tree algorithm is used in offline clustering. MSTSC can improve the clustering quality on non-spherical clusters. Some experiments are carried out in both real data sets and synthetic data sets. Results show that MSTSC algorithm not only can deal with non-spherical clusters effectively, but also has better efficiency and clustering quality. In addition, MSTSC is insensitive to order of input data, and has a good effect for skewed class distributions.

关键词： Cluster analysis

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An Effective Method to Solve the Induced Surface Current for Arbitrary Conducting Objects at Resonant Frequencies

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电子学报(英文版) 2010年第1期19卷 66-68页

作者： SONG Kaihong WU Xianliang Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei China

A novel scheme is developed to compute correctly the induced current based on the Electric field integral equation (EFIE) by the Method of moments (MOM) at resonant frequencies. As a First step, the inaccurate induced current is obtained by solving the EFIE. Then, the scattered magnetic field due to the inaccurate induced current is calculated at any given point on the surface of the object. Finally, the accurate induced current at any given point is determined through the total magnetic field. The proposed approach is applied to the case of the infinitely Perfectly electric conducting (PEC) cylinder and PEC sphere to check its accuracy and efficiency. It is found that the numerical results match the analytical solution or the Combined field integral equation (CFIE) solution.

关键词：感应电流共振频率导体目标表面诱导电场积分方程数值结果总磁场

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FAST COMPUTATION OF WIDEBAND RCS USING CHARACTERISTIC BASIS FUNCTION METHOD AND ASYMPTOTIC WAVEFORM EVALUATION TECHNIQUE

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Journal of Electronics(China) 2010年第4期27卷 453-457页

作者： Sun Yufa Du Yan Shao Yong Key Lab. of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei 230039 China

The Asymptotic Waveform Evaluation (AWE) technique is an extrapolation method that provides a reduced-order model of linear system and has already been successfully used to analyze wideband electromagnetic scattering problems. As the number of unknowns increases, the size of Method Of Moments (MOM) impedance matrix grows very rapidly, so it is a prohibitive task for the computation of wideband Radar Cross Section (RCS) from electrically large object or multi-objects using the traditional AWE technique that needs to solve directly matrix inversion. In this paper, an AWE technique based on the Characteristic Basis Function (CBF) method, which can reduce the matrix size to a manageable size for direct matrix inversion, is proposed to analyze electromagnetic scattering from multi-objects over a given frequency band. Numerical examples are presented to il-lustrate the computational accuracy and efficiency of the proposed method.

关键词： Method of Moments (MOM) Radar Cross Sections (RCS) Characteristic Basis Func-tion (CBF) method Asymptotic Waveform Evaluation (AWE) Multi-objects

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SAR image despeckling via Bayesian shrinkage based on nonsubsampled contourlet transform

SAR image despeckling via Bayesian shrinkage based on nonsub...

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2010 International Conference on Computational and Information Sciences, ICCIS2010

作者： Zhang, De-Xiang Gao, Qing-Wei Wu, Xiao-Pei Key Lab. of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei China

ISBN: (纸本)9780769542706

We propose a novel and efficient SAR image despeckling via Bayesian shrinkage based on nonsubsampled contourlet transform, which has been recently introduced. Despeckling by means of contourlet transform introduce many visual artifacts due to the Gibbs-like phenomena. Nonsubsampled contourlet transform is a flexible multiscale, multidirection and shift-invariant image decomposition that can be efficiently implemented via transform. A Bayesian estimator is applied to the decomposed contourlet coefficients of the logarithmically transformed image to estimate the best value for the noise-free signal. Experimental results show that compared with conventional wavelet despeckling algorithm, the proposed algorithm can achieve an excellent balance between suppresses speckle effectively and preserves image details, and the significant information of original image like textures and contour details is well maintained. © 2010 IEEE.

关键词： Shrinkage

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Study of millimetre-wave generation based on optical frequency multiplication

Study of millimetre-wave generation based on optical frequen...

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IET International Communication Conference on Wireless Mobile and computing (CCWMC 2011)

作者： Yan Ding Jun Zhu Wei-Dong Fang Xiao-Guang Ge Xiang Chen Key Laboratory of Intelligent Computing & Signal Processing Ministry of Education Anhui University Hefei Anhui China Shanghai Research Centre for Wireless Communications China School of Communication and Information Engineering Key Laboratory of Specialty Fiber Optics and Optical Access Net works Shanghai University Shanghai China

ISBN: (纸本)9781618399571

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Fast calculation of wide-band RCS for three-dimensional PEC objects based on preconditioned AWE technique

Fast calculation of wide-band RCS for three-dimensional PEC ...

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URSI International Symposium on signals, Systems, and Electronics (ISSSE)

作者： Zhao, Ke-Ming Sun, Yu-Fa Key Lab. of Intelligent Computing and Signal Processing Ministry Education Anhui University Hefei 230039 China

ISBN: (纸本)9781424463558

The asymptotic waveform evaluation (AWE) technique combined with the method of moments (MOM) is often applied to accelerate the calculation of the wide-band radar cross section (RCS) of the target. However, the technique is still quite time-consuming for solving the inverse of impedance matrix when the objects are electrically large. In this paper, Krylov subspace iterative methods are applied to solve the matrix equation derived from electric field integral equation instead of matrix inverse. The dual threshold incomplete LU factorization preconditioner is adopted to improve the convergence behavior of the Krylov subspace iterative methods. The numerical computation shows that the results in this paper are in good agreement with the results obtained by the method of moments at each frequency, and the computational efficiency is improved greatly. © 2010 IEEE.

关键词： Method of moments

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An efficient technique for extracting singularity arising in RCS computation of cylindrical antenna

An efficient technique for extracting singularity arising in...

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2010 International Conference on Microwave and Millimeter Wave Technology, ICMMT 2010

作者： Li, Jing Sun, Yufa Key Lab. of Intelligent Computing and Signal Processing Anhui University Ministry Education Hefei 230039 China

ISBN: (纸本)9781424457052

Analysis of electromagnetic scattering characteristics from wire antennas using method of moments has been performed over the past decades. In this paper, an efficient technique is adopted to evaluate the potential and reaction integrals arising in radar cross section (RCS) computation of cylindrical antenna by method of moments. The singularity of potential and reaction integrals is extracted through the semi-analytical method. The induced current on the surface and RCS of cylindrical antenna are calculated. Numerical examples are presented to illustrate the computational accuracy and efficiency of the proposed technique. © 2010 IEEE.

关键词： Radar cross section

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