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IET International Radar Conference 2013

作者： Zhang, Chuan-Fang Liu, Chang-Jiang Hu, Cheng Liu, Xiang-Rong Beijing Institute of Technology School of Information and Electronics Beijing 100081 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing China

ISBN: (纸本)9781849196031

The research of statistical properties and simulation methods of radar clutter have vital importance to the design, simulation and development of radar systems. Based on the analysis of some experimental data of forward scattering radar (FSR) clutter, it was found that under low wind speed and narrow dynamic range, the amplitude of FSR clutter was subject to K distribution;while under high wind speed or wide dynamic range, it was subject to lognormal distribution;the clutter power spectrum was subject to the fourth-order all-pole model. With the above statistical analysis, the forward scatter coherent clutter was simulated using a method combining zero-memory nonlinear transformation with spherically invariant random process. The statistical characteristics of the simulated clutter were identical to those of the measured clutter, which verified the validity of this method.

关键词： Radar clutter

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The role of single loading dielectric layer on properties of Frequency Selective Surfaces

The role of single loading dielectric layer on properties of...

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International Workshop on Metamaterials (Meta)

作者： Zhang, S. J. Liu, J. Q. Wang, M. L. Ms, W. M. Liang, W. Liu, X. M. Hou, X. C. National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics

ISBN: (纸本)9781467328081

Frequency selective surfaces (FSS) have attracted researchers from many subjects for decades for its tempting applications such as for radome radar cross section (RCS) reduction, sub-reflector, et. al. Many studies was focused on different type FSS, such as unit shape, dielectric loading, layers of FSS. And it is of popular consideration that double dielectric loading on both sides of FSS be an ideal configuration. In this paper, the type of single side loading, which is more similar to the practical configuration, was studied with the numerical method. And it is found that both the thickness of thick loading layer and the constant of the thin substrate play key roles to the properties of FSS.

关键词： frequency selective surfaces loading LOADING dielectric layer side load numerical methods sidings

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Attitude maneuver path optimization for small scale spacescraft

Attitude maneuver path optimization for small scale spacescr...

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10th IEEE Jubilee International Symposium on Applied Machine Intelligence and Informatics, SAMI 2012

作者： Du, Runle Liu, Jiaqi Wang, Yonghai National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781457701979

During its flight, Spacecrafts need to maneuver its attitude across a number of predefined positions. The order to traverse these attitudes is a combinational optimization problem. In this article, fuel cost is estimated by analyzing the angular momentum change during attitude transitions. Based on this estimation, an optimization algorithm for both fuel-cost and maneuver-time oriented path planner is introduced. Simulation result demonstrated the effectiveness of proposed approach. © 2012 IEEE.

关键词： Attitude control

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FSS design research for improving the wide-band stealth performance of radar absorbing materials

FSS design research for improving the wide-band stealth perf...

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2012 International Workshop on Metamaterials, Meta 2012

作者： Wang, Ming-Liang Zhang, Sheng-Jun Liu, Jia-Qi Liang, Wei Liu, Xue-Mei Liang, X.W. National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical BeiJing 100076 China

ISBN: (纸本)9781467328081

The frequency selective surface (FSS) is designed to improve the wide-band stealth performance of radar absorbing materials (RAM) at the frequency range from 2GHz to 12GHz. The FSS element structure is designed for thin RAM coating, and the electromagnetic wave reflectivity performance of RAM containing FSS is analyzed by using the numerical simulation. The influence of FSS design parameters on the reflectivity of RAM is researched, and the FSS design parameters include the element geometry parameter, the length of the array periods, and the permittivity of substrate material. The research results show that the three absorbing wide-bands can appear and that the reflectivity is lower than -10dB, so the wide-band stealth performance of RAM containing FSS can be improved at the frequency range from 2GHz to 12GHz. © 2012 IEEE.

关键词： Frequency selective surfaces

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Attitude maneuver path optimization for small scale spacescraft

Attitude maneuver path optimization for small scale spacescr...

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International Symposium on Applied Machine Intelligence and Informatics (SAMI)

作者： Runle Du Jiaqi Liu Yonghai Wang Test Physics and Numerical Mathematics National Key Laboratory of Science and Technology Beijing China

关键词： Attitude control Fuels Space vehicles Path planning Switches Optimization Heuristic algorithms

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Effective Observing Area based evaluating method for formation design

Effective Observing Area based evaluating method for formati...

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IEEE AESS European Conference on Satellite Telecommunications (ESTEL)

作者： Runle Du Jiaqi Liu Yonghai Wang Yizhong Fang Gang Meng National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

When multiple flying vehicles collaborate in locating a target, their formation design is an important factor to the error of location. Based on the analyses of contribution that formation design made to the location error, Effective Observing Area is defined as a criterion to assess formation design. An evaluation method for formation design is then proposed in this paper, which can serve as a guide in further formation design. Digital simulation results have proved the effectiveness and correct of this concept.

关键词： Vectors Target tracking Algorithm design and analysis Space vehicles Extraterrestrial measurements

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The role of single loading dielectric layer on properties of frequency selective surfaces

The role of single loading dielectric layer on properties of...

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International Workshop on Metamaterials

作者： S. J. Zhang J. Q. Liu M. L. Wang W. M. Ms W. Liang X. M. Liu X. C. Hou National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Aerospace Science & Industry Defense Technology R & T Center

Frequency selective surfaces (FSS) have attracted researchers from many subjects for decades for its tempting applications such as for radome radar cross section (RCS) reduction, sub-reflector, ***. Many studies was focused on different type FSS, such as unit shape, dielectric loading, layers of FSS. And it is of popular consideration that double dielectric loading on both sides of FSS be an ideal configuration. In this paper, the type of single side loading, which is more similar to the practical configuration, was studied with the numerical method. And it is found that both the thickness of thick loading layer and the constant of the thin substrate play key roles to the properties of FSS.

关键词： Frequency selective surfaces Dielectrics Substrates Loading Load modeling Frequency modulation Equivalent circuits

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FSS design research for improving the wide-band stealth performance of radar absorbing materials

FSS design research for improving the wide-band stealth perf...

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International Workshop on Metamaterials

作者： Wang Ming-liang Zhang Sheng-jun Liu Jia-qi Liang Wei Liu Xue-mei X. W. Liang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China

关键词： Frequency selective surfaces Random access memory Reflectivity Resonant frequency Arrays Substrates

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Effects of discharge types on plasma collisional absorption of electromagnetic waves

Effects of discharge types on plasma collisional absorption ...

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International Workshop on Metamaterials

作者： Runhui Wu Shengjun Zhang Jiaqi Liu Aimin Ren Gang Meng Wei Liang Xuemei Liu National Key Laboratory of Science and Technology on test physics & numerical mathematical Beijing China

In this paper, the collisional absorption mechanism of electromagnetic wave in plasma of different types is studied with numerical methods. The collision frequency and electromagnetic wave which is made by RF discharge in the obturator or DC discharge around the opening space. The computation models are founded for calculating the absorption by the plasma. The FDTD method is presented for simulating the collisional absorption of electromagnetic wave power for one-dimensional homogeneous/inhomogeneous plasma. The emulational results illustrate that there are two conclusions: 1) the homogeneous plasma which is produced by RF discharge in the obturator on collisional absorption of electromagnetic wave can absorb the energy of electromagnetic wave effectively in the finite bandwidth; 2) the inhomogeneous plasma which is produced by DC discharge around the opening space can absorb the energy of electromagnetic wave availably both in the wide bandwidth and from low-frequency to high-frequency.

关键词： Plasmas Discharges (electric) Absorption Radio frequency Nonhomogeneous media Electromagnetic scattering Attenuation

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Double-stage Metamodel and Its Application in Aerodynamic Design Optimization

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Chinese Journal of Aeronautics 2011年第5期24卷 568-576页

作者： ZHANG Dehu GAO Zhenghong HUANG Likeng WANG Mingliang National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi＇an 710072 China National Key Laboratory of Science and Technology on Test Physics ＆ Numerical Mathematical Beijing 100076 China

Constructing metamodel with global high-fidelity in design space is significant in engineering design. In this paper, a double-stage metamodel （DSM） which integrates advantages of both interpolation metamodel and regression metamodel is constructed. It takes regression model as the first stage to fit overall distribution of the original model, and then interpolation model of regression model approximation error is used as the second stage to improve accuracy. Under the same conditions and with the same samples, DSM expresses higher fidelity and represents physical characteristics of original model better. Besides, in order to validate DSM characteristics, three examples including Ackley function, airfoil aerodynamic analysis and wing aerodynamic analysis are investigated, In the end, airfoil and wing aerodynamic design optimizations using genetic algorithm are presented to verify the engineering applicability of DSM.

关键词： optimization genetic algorithm double-stage metamodel Kriging BP neural network Latin hypercube Parsecmethod

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