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2017 International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2017

作者： Zhang, Shengjun Wang, Mingliang Ai, Xia Wang, Weidong Wu, Runhui Liu, Xin Liu, Jiaqi Meng, Gang Sun, Yuan National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China Institute of Effectiveness Evaluation of Flying Vehicle Beijing China

In this paper, the general of artificial electromagnetic structure with analog to the natural materials were briefly reviewed. The lattice theory of artificial structure was suggested to be built. © 2017 Applied ... 详细信息

ISBN: (纸本)9780996007856

关键词： Lattice theory

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A Novel Gcv-Based Criterion for Parameter Selection In Image Deconvolution

A Novel Gcv-Based Criterion for Parameter Selection In Image...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Feng Xue Thierry Blu Jiaqi Liu Xia Ai National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 China Dept. of Electronic Engineering The Chinese University of Hong Kong Shatin N.T. Hong Kong

ISBN: (纸本)9781538646595

A proper selection of regularization parameter is essential for regularization-based image deconvolution. The main contribution of this paper is to propose a new form of generalized cross validation (GCV) as a criterion for this optimal selection. Incorporating a nil-trace non-linear estimate, we develop this new GCV based on Stein's unbiased risk estimate (SURE)-an unbiased estimate of mean squared error (MSE). The key advantage of this GCV over SURE is that it does not require the knowledge of noise variance. We exemplify this criterion with both Tikhonov regularization and l_1-based sparse deconvolution. In particular, we develop a recursive evaluation of GCV for the l_1-estimate based on iterative soft-thresholding (IST) algorithm. numerical experiments demonstrate the nearly optimal parameter selection and negligible loss of its resultant deconvolution quality.

关键词： Image deconvolution regularization parameter generalized cross validation (GCV) Stein's unbiased risk estimate (SURE) deconvolution Mean square error optimal selection optimal parameter Imagery (Psychotherapy) Image images

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The Probability Density Function for Network Coding with Three Input Flows

The Probability Density Function for Network Coding with Thr...

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International Conference on Computers, Communications, and Systems (ICCCS)

作者： Xiangrong Liu Yaping Liang Qing Chang Xianxu Li National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China School of Electronic Information Engineering Beihang University Beijing China State grid information & communication branch Beijing China

ISBN: (纸本)9781538663516

Now many researches have been studying the optimization between throughput/energy consuming and delay with a couple of independent input flows in network coding (NC). However, the implementation of network coding (NC) requires a thorough investigation of its impact on relevant queueing systems which little work focuses on. In this paper, the scenario with three independent Poisson input flows based on our previous work about the pdf with two independent Poisson input flows., and one output flow is considered. The asynchronous NC-based strategy is that a new arrival evicts a head packet holding in its queue when waiting for another packet from the other flow to encode. The three flows are divided into two parts for getting the probability density function (pdf) of the output flow. The pdf for the output flow which contains both coded and uncoded packets is derived. Besides, the statistic characteristics of this strategy are analyzed. These results are verified by numerical simulations.

关键词： Probability density function Network coding Encoding Relays Merging Simulation numerical simulation

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Meta or select?* : —history, argument and prospective about MTMs and FSS

Meta or select?* : —history, argument and prospective about...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Shengjun Zhang Mingliang Wang Xia Ai Yichun Cui Xin Liu Jiaqi Liu Gang Meng Zhaohui Qi Yuan Sun Yunhui Tang Hui Xue National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics Beijing China The Institute of Effectiveness Evaluation of Flying Vehicle Beijing China School of materials science and technology Beijing University of Technology Beijing China Beijing Institute of system engineering Beijing China

In this paper, the development history of metamaterials (MTMs) and Frequency selective surfaces (FSS) was sketched, and the two conception was discussed. Furthermore, state of the art of both terms was introduced and ... 详细信息

关键词： Frequency selective surfaces Metamaterials Lattices Crystals physics Electromagnetics Sun

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Recursive Evaluation of Sure for Total Variation Denoising

Recursive Evaluation of Sure for Total Variation Denoising

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IEEE International Conference on Acoustics, Speech and Signal Processing

ISBN: (纸本)9781538646595

Recently, total variation (TV)-based regularization has become a standard technique for signal denoising. The reconstruction quality is generally sensitive to the value of regularization parameter. In this work, based on Cham-bolle's algorithm, we develop two data-driven optimization schemes based on minimization of Stein's unbiased risk estimate (SURE)-statistically equivalent to mean squared error (MSE). First, we propose a recursive evaluation of SURE to monitor the estimation error during Chambolle's iteration;the optimal value is then identified by the minimum SURE. Second, for fast optimization, we perform alternating update between regularization parameter and solution within Chambolle's iteration. We exemplify the proposed methods with both 1-D and 2-D signal denoising. numerical experiments show that the proposed methods lead to highly accurate estimate of regularization parameter and nearly optimal denoising performance.

关键词： Signal denoising total variation (TV) Stein's unbiased risk estimate (SURE) Chambolle's algorithm

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A method for feature extraction based on SVD and machine learning

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IOP Conference Series: Materials science and Engineering 2019年第5期569卷

作者： Wei Mao Shuxian Huang Xin Liu Hongyan Liu Jiaqi Liu Yi Shu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Institute of Precision Mechatronics and Controls 100076 China Beijing Institute of Long March Vehicle 100076 China

By studying the shortcomings of feature, which extracted from Radar-Cross Section(RCS),using mathematical and statistical method, using the idea of extracting abstract features in image recognition and speech recognition by artificial intelligence for reference[2][3]. This paper explores the possibility of extracting abstract features of target's RCS sequence, and proposes an abstract feature extraction method of RCS sequence based on singular value decomposition(SVD) feature decomposition. Because of the poor interpretability of abstract features, four different machine learning algorithms are used to classify the extracted Abstract features. The experimental results show that the machine learning algorithm can classify different types of spatial objects with high accuracy, which shows that the RCS features of different spatial objects can be characterized by abstract features.

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Suppressing the effects of ionospheric scintillation on geosynchronous SAR by optimised orbit design

Suppressing the effects of ionospheric scintillation on geos...

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2017 International Conference on Radar Systems, Radar 2017

作者： Li, YuanHao Liu, XiangRong Hu, Cheng Dong, XiChao School of Information and Electronics Beijing Institute of Technology 100081 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Key Laboratory of Embedded Real-time information Processing Technology 100081 China

ISBN: (纸本)9781785615153

An L band geosynchronous synthetic aperture radar (GEO SAR) will be sensitive to ionosphere scintillation because of its low carrier frequency. Meanwhile, because of the high orbit, GEO SAR has a higher probability to meet ionospheric scintillation. In this paper, we propose an orbit strategy for eliminating the impacts of ionospheric scintillation. It is realized by selecting a proper orbit element (time past perigee) to avoid imaging for the sensitive region of ionospheric scintillation during the eruption time interval of ionospheric scintillation with the highest probability. Finally, the simulation based on systems tool kit (STK) software was conducted to verify the effectiveness of the method. © 2017 Institution of Engineering and technology. All rights reserved.

关键词： Synthetic aperture radar

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Parallel pipeline algorithm of real time star map preprocessing

Parallel pipeline algorithm of real time star map preprocess...

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Chinese Society for Optical Engineering Conferences, CSOE 2016

作者： Wang, Hai-Yong Qin, Tian-Mu Liu, Jia-Qi Li, Zhi-Feng Li, Jian-Hua School of Aeronautics and Astronautics Beihang University Beijing100083 China Beijing Institute of Space Long March Vehicle Beijing100076 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing100076 China

ISBN: (纸本)9781510610118

To improve the preprocessing speed of star map and reduce the resource consumption of embedded system of star tracker, a parallel pipeline real-time preprocessing algorithm is presented. The two characteristics, the mean and the noise standard deviation of the background gray of a star map, are firstly obtained dynamically by the means that the intervene of the star image itself to the background is removed in advance. The criterion on whether or not the following noise filtering is needed is established, then the extraction threshold value is assigned according to the level of background noise, so that the centroiding accuracy is guaranteed. In the processing algorithm, as low as two lines of pixel data are buffered, and only 100 shift registers are used to record the connected domain label, by which the problems of resources wasting and connected domain overflow are solved. The simulating results show that the necessary data of the selected bright stars could be immediately accessed in a delay time as short as 10us after the pipeline processing of a 496×496 star map in 50Mb/s is finished, and the needed memory and registers resource total less than 80kb. To verify the accuracy performance of the algorithm proposed, different levels of background noise are added to the processed ideal star map, and the statistic centroiding error is smaller than 1/23 pixel under the condition that the signal to noise ratio is greater than 1. The parallel pipeline algorithm of real time star map preprocessing helps to increase the data output speed and the anti-dynamic performance of star tracker. © 2017 SPIE.

关键词： Pipelines

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The Way from natural to artificial - the story of Periodic Electromagnetic Structures

The Way from natural to artificial - the story of Periodic E...

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International Applied Computational Electromagnetics Society Symposium in China

作者： Shengjun Zhang Mingliang Wang Xia Ai Weidong Wang Runhui Wu Xin Liu Jiaqi Liu Gang Meng Yuan Sun National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics The Institute of Effectiveness Evaluation of Flying Vehicle

In this paper, the general of artificial electromagnetic structure with analog to the natural materials were briefly reviewed. The lattice theory of artificial structure was suggested to be built.

ISBN: (纸本)9781509043118

In this paper, the general of artificial electromagnetic structure with analog to the natural materials were briefly reviewed. The lattice theory of artificial structure was suggested to be built.

关键词： Artificial structure Electromagnetic lattice Artificial structure lattice theory natural material ELECTROMAGNETIC

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Dual-band checkerboard plasma electromagnetic surface for radar cross section reduction

Dual-band checkerboard plasma electromagnetic surface for ra...

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IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP)

作者： Qiang Xu Zhifeng Li Jinjun Mo National University of Defense Technology Changsha China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China

ISBN: (纸本)9781538616093

Radar cross section (RCS) can be reduced along the principal planes by applying electromagnetic band gap (EBG) structures. Checkerboard plasma electromagnetic surface (PES), combining with EBG and plasma layer, can realize a narrow band near 3 GHz and a wide band 10-dB radar cross section reduction (RCSR) covered X-band, by redirecting the scattered fields towards four quadrants. Bistatic RCS of the checkerboard PES is simulated and the results compared to the corresponding perfect electric conductor (PEC) surface show that the maxima of the bistatic RCS pattern are reduced by 5.4 dB at fixed frequency 10 GHz.

关键词： Plasmas Periodic structures Metamaterials Electromagnetics Radar cross-sections Electromagnetic scattering

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