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IET International Radar Conference 2013

作者： Chao, Zhou Yan, Zhu Can Cheng, Hu Rong, Liu Xiang Insititute of Intelligent Structure and System Soochow University Suzhou China Department of Electronic Engineering Beijing Institute of Technology Beijing China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical Beijing China

ISBN: (纸本)9781849196031

The Doppler shift, azimuth and elevation angles estimation is the precondition of target tracking and SISAR imaging in forward scatter radar (FSR). With the utilization of a spacetime processing (STP) algorithm, the Doppler shift and azimuth angle or elevation angle can be jointly estimated. The impacts of the observation interval and multipath interference on parameters estimation accuracy are analyzed. The quasioptimal observation interval is given after considering the contradiction between the frequency resolution and dynamic error. The correctness of these analyses is verified by quantitative simulation results.

关键词： Parameter estimation

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Recent developments on the lagrangian and remapping methods for compressible fluid flows

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International Conference on numerical Methods for Hyperbolic Equations: Theory and Applications

作者： Juan, Cheng Shu, Chi-Wang National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics China Division of Applied Mathematics Brown University United States

ISBN: (纸本)9780415621502

The Lagrangian method and the Arbitrary Lagrangian-Eulerian method (ALE) are widely used in many fields, especially for multi-material flow simulations, due to their distinguished advantage in capturing material interfaces automatically. In this paper we give a short survey on our recent research on the Lagrangian scheme and the remapping method, both of which constitute essential and important components of the ALE method. Specifically, we first introduce a class of high order Lagrangian schemes which are based on Essentially Non-Oscillatory (ENO) and Weighted Essentially Non-Oscillatory (WENO) reconstructions. The schemes are constructed both on straight-line quadrilateral meshes and on curvilinear quadrilateral meshes. Meanwhile, two approaches for high order time discretization in the Lagrangian scheme are investigated, namely, the Total Variation Diminishing (TVD) Runge-Kutta time discretization and the Lax-Wendroff (LW) type time discretization. Next, we give a class of cell-centered Lagrangian schemes with the properties of both conservation and spherical-symmetry-preserving in two-dimensional cylindrical coordinates. After that, we summarize a high order conservative ENO remapping algorithm. At last, several numerical examples are shown to further demonstrate the performance of these schemes. © 2013 Taylor & Francis Group, London.

关键词： Lagrange multipliers

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Fast Data Fusion Algorithm for Tracking Maneuvering Target by Vehicle Formation

Fast Data Fusion Algorithm for Tracking Maneuvering Target b...

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IEEE Radar Conference

作者： Runle Du Jiaqi Liu Yonghai Wang Zhifeng Li Chunyue Gao National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Aero-Top Hi-Tech Corporation Ltd.

ISBN: (纸本)9781467357920

When multiple flying vehicles with bearing-only tracking collaborate in locating a target, observation data fusion is required to compensate the drift of navigation system, the noise from observation system, and the unknown maneuvering of target object. Kalman Filtering of nonlinear observation data needs a huge amount of computation, and will cause trouble to onboard embedded computing systems. Least Squared Error (LSE) can process nonlinear measurements at high speed, but the observation noise may be amplified due to the intrinsic deficiency. In this paper, a Fast Data Fusion algorithm is proposed. It combined these two methodologies. LSE is used as the preprocessing stage to build a coarse estimation and Kalman Filtering is used to further eliminate noises from preprocessed estimations. Simulation results show that, proposed method uses no more than 3% of computation time of Kalman Filtering and achieved similar or even better target locating precision.

关键词： Formation Flying Bearing-only Tracking Passive Target Location Fast Data Fusion Kalman Filtering

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A New Discontinuous Galerkin Method for Parabolic Equations with Discontinuous Coefficient

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numerical mathematics(Theory,Methods and Applications) 2013年第2期6卷 325-342页

作者： Rongpei Zhang Xijun Yu Xia Cui Xiaohan Long Tao Feng School of Sciences Liaoning Shihua UniversityFushun 113001LiaoningChina National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China School of Mathematics and Information Ludong UniversityYantai 264025ShandongChina

In this paper,a new discontinuous Galerkin method is developed for the parabolic equation with jump coefficients satisfying the continuous flow *** analysis shows that this method is L^(2) *** the finite element space consists of interpolative polynomials of degrees k,the convergent rate of the semi-discrete discontinuous Galerkin scheme has an order of δ(h^(k)).numerical examples for both 1-dimensional and 2-dimensional problems demonstrate the validity of the new method.

关键词： Parabolic equation discontinuous coefficient discontinuous Galerkin method error estimate stability analysis

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Statistical analysis and simulation method of forward scattering clutter in bistatic radar

Statistical analysis and simulation method of forward scatte...

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IET International Radar Conference 2013

作者： Chuan-fang Zhang Chang-jiang Liu Cheng Hu Xiang-rong Liu School of Information and Electronics Beijing Institute of Technology China 100081 National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China

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.

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Statistical analysis and simulation method of forward scattering clutter in bistatic radar

Statistical analysis and simulation method of forward scatte...

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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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Collimation of Energetic Electrons from a Laser-Target Interaction by a Magnetized Target Back Plasma Preformed by a Long-Pulse Laser

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Physical Review Letters 2014年第21期112卷 215003-215003页

作者： H. B. Zhuo Z. L. Chen Z. M. Sheng M. Chen T. Yabuuchi M. Tampo M. Y. Yu X. H. Yang C. T. Zhou K. A. Tanaka J. Zhang R. Kodama College of Science National University of Defense Technology Changsha 410073 People’s Republic of China Graduate School of Engineering Osaka University 2-1 Yamada-oka Suita Osaka 565-0871 Japan MOE Key Laboratory for Laser Plasmas and Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 People’s Republic of China Department of Physics SUPA University of Strathclyde Glasgow G4 0NG United Kingdom Institute of Laser Engineering Osaka University 2-6 Yamada-oka Suita Osaka 565-0871 Japan Institute for Fusion Theory and Simulation and Department of Physics Zhejiang University Hangzhou 310027 People’s Republic of China Institute for Theoretical Physics I Ruhr University Bochum D-44780 Germany Institute of Applied Physics and Computational Mathematics Beijing 100094 People’s Republic of China

It is demonstrated experimentally and by numerical simulations that the presence of a long-pulse-laser-created back plasma on the target backside can focus the relativistic electrons produced by short-pulse laser interaction with the front of a solid target. Comparing this to that without the back plasma, the number density of the fast electrons is increased by one order of magnitude, and their divergence angle is reduced fivefold. The effect is attributed to the absence of the backside sheath electric field and the collimation effect of the megagauss self-generated baroclinic magnetic field there. Such an acceleration scheme can be useful to applications requiring high-energy and charge-density electron bunches, such as fast ignition in inertial fusion.

关键词： COMPUTER simulation LASER pulses ELECTRONS PLASMA acceleration ACCELERATION (Mechanics)

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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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Quantum phase transition in a three-level atom-molecule system

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Physical Review A 2013年第1期88卷 013602-013602页

作者： Sheng-Chang Li Li-Bin Fu Fu-Li Li School of Science Xi'an Jiaotong University Xi'an 710049 China National Key Laboratory of Science and Technology on Computation Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Center for Applied Physics and Technology Peking University Beijing 100084 China

We adopt a three-level bosonic model to investigate the quantum phase transition in an ultracold atom-molecule conversion system which includes one atomic mode and two molecular modes. Through thoroughly exploring the properties of energy-level structure, fidelity, and adiabatic geometric phase, we confirm that the system exhibits a second-order phase transition from an atom-molecule mixture phase to a pure molecule phase. We give the explicit expression of the critical point and obtain two scaling laws to characterize this transition. In particular, we find that both the critical exponents and the behavior of the ground-state geometric phase have obviously changed in contrast to a similar two-level model. Our analytical calculations show that the ground-state geometric phase jumps from zero to π/3 at the critical point. This discontinuous behavior has been checked by numerical simulations and it can be used to identify the phase transition in the system.

关键词： QUANTUM phase transitions ATOM-molecule collisions GEOMETRIC quantum phases COMPUTER simulation PHASE transformations (physics) CRITICAL point

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