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 collect...
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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.
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, ...
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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.
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...
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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.
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 algorit...
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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.
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...
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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.
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 ...
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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.
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 man...
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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, ...
ISBN:
(纸本)9781618399571
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.
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 techni...
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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 an...
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