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IET International Radar Conference 2015

作者： Ai, Xia Liu, Shendong Zhang, Shengjun Wang, Mingliang Liu, Jiaqi Meng, Gang Zhou, Hongchao National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical China

ISBN: (纸本)9781849199940

In this paper, a dispersive conformal FDTD method have been proposed to accurate model the interface between two adjacent dispersive mediums. The method is based on the technology of area average between two adjacent dispersive interfaces, which is different from existing dispersive conformal FDTD schemes which involve with the interface between free space and dispersive medium. numerical results show the proposed method would enhance the accurate level compared to the staircasing FDTD scheme involved in the inhomogeneous plasma.

关键词： numerical methods

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Higher order shift operater FDTD scheme for scattering of cloaking structure

Higher order shift operater FDTD scheme for scattering of cl...

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IET International Radar Conference 2015

作者： Ai, Xia Zhang, Shengjun Wang, Mingliang Wang, Weidong Liu, Jiaqi Liu, Chengguo Liu, Xuemei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical China

ISBN: (纸本)9781849199940

In this paper, a higher-order shift operater (SO) FDTD scheme with second-order accuracy in time and fourth-order in space has been proposed to accurately model scattering of perfect electronic conductor coated with cloaking structures. Several different electromagnetic parameters of the cloaks are taken into account using SO-FDTD method. numerical results indicate that the proposed method is more accuracy than the traditioinal method maintaining the same grid size. Scattering of different kinds of simplified cylindrical cloaks including thickness and loss are presented and could be served as further study on this subject.

关键词： Finite difference time domain method

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Advances in the Researches of the Middle and Upper Atmosphere in China in 2014-2016

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空间科学学报 2016年第5期36卷 738-752页

作者： CHEN Zeyu XU Jiyao HU Xiong CHEN Hongbin CHEN Wen WEI Ke BIAN Jianchun TIAN Wenshou ZHANG Shaodong REN Rongcai DOU Xiankang Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 National Space Science Center Chinese Academy of Sciences Beijing 100190 Institute of Atmospheric Physics Chinese Academy of Scienees Beijing 100029 School of Atmospheric Sciences Lanzhou University Lanzhou 730000 School of Electronic Information Wuhan University Wuhan 430072 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 School of Earth and Space Sciences University of Science and Technology of China Hefei 230026

In this report the research results by Chinese scientists in 2014—2016 are *** focuses are placed on the researches of the middle and upper atmosphere,specifically the researches associated with ground-based observation capabihty development,dynamical processes,and properties of circulation and chemistry-climate coupling of the middle atmospheric layers.

关键词：中高层大气中国科学家研究成果观察能力耦合特性大气化学中间层气候

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The research on the effects of an active FSS with circle element on the characteristics of Radar Absorbing Materials

The research on the effects of an active FSS with circle ele...

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IET International Radar Conference 2015

作者： Wang, Ming-Liang Zhang, Sheng-Jun Liu, Jia-Qi Wang, Wei-Dong Ai, Xia Liu, Shengdong Liang, Wei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing China

ISBN: (纸本)9781849199940

An active frequency selective surface (FSS) is designed, and is combined with Radar Absorbing Materials to form a composite absorbing structure. Based on the equivalent theory that the PIN diode can be regarded as resistance, the voltage-loading resistance of active FSS element is researched for RAM containing FSS, and the electromagnetic wave reflectivity performance is analyzed. The influence of active FSS design parameters on the reflectivity of RAM is researched, and the FSS design parameters include the voltage-loading manner, the resistance parameter, and the position in the RAM. The research result shows that the resonance frequency of RAM containing FSS can be dynamically adjusted from 3GHz to 4GHz by changing voltage-loading resistance of active FSS, and the reflectivity can be reduced from -13dB to -35dB.

关键词： Reflection

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ISAR target micro-Doppler feature extraction and recognition method based on PCA and ICA

ISAR target micro-Doppler feature extraction and recognition...

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IET International Radar Conference 2015

作者： Bai, Jinliang Jiang, Zhiye Liu, Jiaqi Gao, Lu Liu, Hongyan Xu, Feng Qin, Peng Li, Hu Chen, Shuyuan Liu, Shengdong National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781849199940

Micro-Doppler features can be regarded as a unique signature of ISAR targets and provide critical information for target recognition. This paper proposes an ISAR micro-Doppler feature extraction and recognition method based on combination algorithm of principle component analysis (PCA) and independent component analysis (ICA). In order to decrease computation burden, PCA algorithm is first applied to reduce dimension and second order correlation, and then ICA decomposes micro-Doppler represented in time frequency domain into a set of independent basis components, which consist the micro-Doppler feature subspace. Target recognition is transformed to calculate the projection coefficient in the subspace. The experimental results verify the correctness and effectiveness of the proposed method.

关键词： Independent component analysis

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Communication performance optimization of spaceborne/airborne Radar networks

Communication performance optimization of spaceborne/airborn...

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IET International Radar Conference 2015

作者： Li, Hu Gao, Lu Liu, Jiaqi Liu, Hongyan Jiang, Zhiye Bai, Jinliang Xu, Feng Chen, Shuyuan Liu, Shengdong Zhu, Guangsheng Liu, Xuemei National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781849199940

In this paper, we investigate communication performance optimization problem of spaceborne/airborne Radar networks. A model of spaceborne/airborne Radar networks with propagation delay and power constraints is given first. A Quadric Lyapunov function based Algorithm (QLA) is then proposed aiming at greedily minimizing an expression containing Lyapunov drift. We prove two main conclusions, one is that the communication network of spaceborne/airborne Radars under QLA is stable, the other is that power constraints are met. Upper bounds of queue backlogs and a lower bound of utility function are established through theoretical analysis, and how propagation delay jeopardizes utility performance is also demonstrated. Simulation of QLA is carried out in a scenario consists of 6 nodes, and results are in accordance with theoretical conclusions.

关键词： Lyapunov methods

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Study of RF structure for W band sheet beam EIK

Study of RF structure for W band sheet beam EIK

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IET International Radar Conference 2015

作者： Chen, Shuyuan Jiang, Zhiye Liu, Jiaqi Gao, Lu Bai, Jingliang Liu, Hongyan Meng, Gang Xu, Feng Li, Hu Liu, Chengguo Zhu, Guangsheng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781849199940

Microwave tubes are vacuum electron devices used for the generation and amplification of radio frequencies in the microwave frequency range. Klystron is a kind of microwave tubes which is used in radar. A sheet-beam Extended Interaction Klystron (SBEIK) is an attractive MMW amplifier because of its high gain per unit length and compact configuration. The RF structure is an important part of the whole tube, which is used for beam wave interaction. In this paper, two kinds of barbell cavity has been studied. The difference between the separating multi-gap barbell resonant cavity and the strong coupling multi-gap barbell cavity has been discussed. RF parameters have been calculated by 3D simulations.

关键词： Microwaves

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RCS analysis of disk target covered with non-uniform plasma

RCS analysis of disk target covered with non-uniform plasma

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IET International Radar Conference 2015

作者： Wu, Runhui Liu, Jiaqi Liu, Xin Meng, Gang Ren, Aimin Qi, Zhaohui National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing100076 China

ISBN: (纸本)9781849199940

This paper presents a model of RCS characteristic of non-uniform plasma sheltering disk target, by considering the absorption and refraction of electromagnetic wave, and combining graphic electromagnetic and ray tracking methods. The results show that: (1) RCS is reduced more than 10dB at wide-band frequency of electromagnetic wave, when the incident direction of electromagnetic wave is near the vertical surface. (2)For optimization of RCS reduction scheme, it is effective to optimize the relation between the plasma parameters (including electronic density, collision frequency, over-dense target scale) and incident wavelength. When the area of over-dense surface was larger than the target scale, the larger the collision frequency could lead to greater RCS reduction. When the area of over-dense scale was smaller than target, the RCS reduction has to be achieved by increasing electronic density and collision frequency.

关键词： Radar cross section

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An iterative sure-let approach to sparse reconstruction

An iterative sure-let approach to sparse reconstruction

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

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

Sparsity-promoting regularization is often formulated as ℓv-penalized minimization (0

ISBN: (纸本)9781479999897

Sparsity-promoting regularization is often formulated as ℓv-penalized minimization (0

关键词： Optimization Jacobian matrices Convergence Iterative methods Minimization Standards Signal to noise ratio

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China's promotion on space security and safety 66

China's promotion on space security and safety

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66th International Astronautical Congress 2015: Space - The Gateway for Mankind's Future, IAC 2015

作者： Zhang, Shengjun Liu, Jiaqi Liu, Xin China Academy of Launch Vehicle Technology National Key Laboratory on Test Physics and Numerical Mathematics China

ISBN: (纸本)9781510818934

As the development of the activities in space, militarization on space and space debris bring more and more risks and danger to the world. It is a worldwide problem to keep space in a security and safety situation. With years of development in astronautics, more and more space activities actualized in China as well as the cooperation on space items between China and many other countries, both academic groups and government of China now pay more attentions on the activities itself and the space environment for peace use of space and the convenient life in the information days. Many researches have been sponsored by the government in recent three decades. There are two types of research groups, including the academic part (such the professors and their students) and space organizations, concerning on topics such as legal affairs, space debris and other. The study of these groups as well as their cooperation with international groups contributed much to concerning and the decision-making of the government, even leading to the TCBM and PPWT.

关键词： Space debris

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