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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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Comparison of Nonlinear Local Lyapunov Vectors with Bred Vectors, Random Perturbations and Ensemble Transform Kalman Filter Strategies in a Barotropic Model

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Advances in Atmospheric sciences 2016年第9期33卷 1036-1046页

作者： Jie FENG Ruiqiang DING Jianping LI Deqiang LIU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 College of Earth Science University of Chinese Academy of SciencesBeijing 100049 Global Systems Division Earth System Research Laboratory/Oceanic and Atmospheric Research/National Oceanic and Atmospheric AdministrationBoulderCO80305USA Plateau Atmosphere and Environment Key Laboratory of Sichuan Province Chengdu University of Information TechnologyChengdu 610225 College of Global Change and Earth System Sciences Beijing Normal UniversityBeijing 100875 Joint Center for Global Change Studies Beijing 100875 Fujian Meteorological Observatory Fuzhou 350001

The breeding method has been widely used to generate ensemble perturbations in ensemble forecasting due to its simple concept and low computational cost. This method produces the fastest growing perturbation modes to catch the growing components in analysis errors. However, the bred vectors （BVs） are evolved on the same dynamical flow, which may increase the dependence of perturbations. In contrast, the nonlinear local Lyapunov vector （NLLV） scheme generates flow-dependent perturbations as in the breeding method, but regularly conducts the Gram-Schmidt reorthonormalization processes on the perturbations. The resulting NLLVs span the fast-growing perturbation subspace efficiently, and thus may grasp more com- ponents in analysis errors than the BVs. In this paper, the NLLVs are employed to generate initial ensemble perturbations in a barotropic quasi-geostrophic model. The performances of the ensemble forecasts of the NLLV method are systematically compared to those of the random pertur- bation （RP） technique, and the BV method, as well as its improved version--the ensemble transform Kalman filter （ETKF） method. The results demonstrate that the RP technique has the worst performance in ensemble forecasts, which indicates the importance of a flow-dependent initialization scheme. The ensemble perturbation subspaces of the NLLV and ETKF methods are preliminarily shown to catch similar components of analysis errors, which exceed that of the BVs. However, the NLLV scheme demonstrates slightly higher ensemble forecast skill than the ETKF scheme. In addition, the NLLV scheme involves a significantly simpler algorithm and less computation time than the ETKF method, and both demonstrate better ensemble forecast skill than the BV scheme.

关键词： ensemble forecasting bred vector nonlinear local Lyapunov vector ensemble transform Kalman filter

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Design and Particle-in-Cell Simulation of Sub-THz Sheet Beam EIK

Design and Particle-in-Cell Simulation of Sub-THz Sheet Beam...

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International Conference on Infrared, Millimeter, and Terahertz Waves

作者： Shuyuan Chen Jiaqi Liu Yongtao Shui Lu Gao Zhiye Jiang Jingliang Bai Hongyan Liu Xin Liu Xuefeng Zhang Feng Xu Peng Qin Hu Li National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 P. R. China

ISBN: (纸本)9781467384865

In this paper, a novel and small sub-terahertz (THz) sheet beam extended interaction klystron (EIK) has been designed. With the help of a three-dimensional (3D) particle-in-cell (PIC) simulation, design and optimizing geometry of THz sheet beam EIK is performed. The interaction system consists of two dumbbell five-gap cavities, one is used for input cavity, the other is output cavity. The operating center frequency of sub-THz sheet beam EIK is 94.5GHz. The gain of whole tube is higher than 24.8dB, which is only consisted of two resonant cavities. If there are more cavities, the tube will get higher gain. This is a big progress and is very useful for the design of lightweight, mini-type and low input power but with high output power THz sheet beam EIK.

关键词： Cavity resonators Power generation Particle beams Power amplifiers Gain Klystrons

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The Study on Porous Media Phase Change Coupling Heat transfer model in Enclosed Metal Cavity

The Study on Porous Media Phase Change Coupling Heat transfe...

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The 2nd International Conference on Materials science and Engineering technology (MSET 2015)

作者： WU Run-hui LIU Jia-qi LIU Xin REN Ai-min ZHANG Sheng-jun MENG Gang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical

This thesis is aimed to the external instantaneous high energy heat source,according to enclosed metal cavity,porous medium in the cavity,porous media can by phase change heat transfer characteristic of variegated medium coupling state target's special requirements in the field of aerospace,it is innovatively to put forward a kind of applicable to simulate sealed coupling target,under the condition of instant high energy heat source excitation,By heat source-metal cavityporous medium—porous medium's phase-changeable phase change process heat-transfer characteristic numerical calculation model-creation approach,in use of the metal cavity,in the porous medium incompressible flow phase transition of working medium's heat energy conservation,momentum conservation and mass conservation principle,it is to establish analysis model of coupled heat transfer characteristics of multiple parts,in order to acquire the full target area of airtight coupling state targets,temperature field,pressure field,velocity field and phase change of phase transition of working medium characteristics change with time and space change numerical value to analog *** study results points out:when the incentive heat source keep constant,the change rule of full target area temperature,pressure flow rate and phase change characteristic parameters is in conformity with theory of heat transfer *** heat transfer model can be popularized and applied to the optimization design of incentive heat source,and comprehensive performance optimization of enclosed coupling state objects.

关键词： Enclosed metal cavity,Porous foam materials,Phase transition working medium,Heat transfer model,numerical modeling

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

ISBN: (纸本)9781510822023

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 traditional 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 Higher-order algorithm Scattering of cloaks

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Dispersive FDTD scheme with conformal technology for analyzing electromagnetic scattering of inhomogeneous plasma array

Dispersive FDTD scheme with conformal technology for analyzi...

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IET International Radar Conference 2015

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

ISBN: (纸本)9781510822023

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： Conformal method FDTD electromagnetic scattering

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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： Runhui Wu Jiaqi Liu Xin Liu Gang Meng Aimin Ren Zhaohui Qi National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing 100076

ISBN: (纸本)9781510822023

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： Disk Target Electromagnetic Wave Non-uniform Plasma Radar Cross Section(RCS)

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The seasonal variations in the significant wave height and sea surface wind speed of the China's seas

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Acta Oceanologica Sinica 2015年第9期34卷 58-64页

作者： ZHENG Chongwei PAN Jing TAN Yanke GAO Zhansheng RUI Zhenfeng CHEN Chaohui College of Meteorology and Oceanography People’s Liberation Army University of Science and Technology National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of Sciences Dalian Naval Academy

Long-term variations in a sea surface wind speed （WS） and a significant wave height （SWH） are associated with the global climate change, the prevention and mitigation of natural disasters, and an ocean resource exploitation, and other activities. The seasonal characteristics of the long-term trends in China＇s seas WS and SWH are determined based on 24 a （1988-2011） cross-calibrated, multi-platform （CCMP） wind data and 24 a hindcast wave data obtained with the WAVEWATCH-III （WW3） wave model forced by CCMP wind data. The results show the following. （1） For the past 24 a, the China＇s WS and SWH exhibit a significant increasing trend as a whole, of 3.38 cm/（s.a） in the WS, 1.3 cm/a in the SWH. （2） As a whole, the increasing trend of the China＇s seas WS and SWH is strongest in March-April-May （MAM） and December-January-February （DJF）, followed by June-July-August （JJA）, and smallest in September-October-November （SON）. （3） The areal extent of significant increases in the WS was largest in MAM, while the area decreased in JJA and DJF; the smallest area was apparent in SON. In contrast to the WS, almost all of China＇s seas exhibited a significant increase in SWH in MAM and DJF; the range was slightly smaller in JJA and SON. The WS and SWH in the Bohai Sea, the Yellow Sea, East China Sea, the Tsushima Strait, the Taiwan Strait, the northern South China Sea, the Beibu Gull and the Gulf of Thailand exhibited a significant increase in all seasons. （4） The variations in China＇s seas SWH and WS depended on the season. The areas with a strong increase usually appeared in DJF.

关键词： sea surface wind speed significant wave height long-term variation seasonal difference

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Guidance law recognition of target pursuing vehicle

Guidance law recognition of target pursuing vehicle

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IEEE Metrology for Aerospace

作者： Runle Du Jiaqi Liu Zhifeng Li Zhenhong Niu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

Research on guidance law has begun to incorporate behavior information from non-cooperative target, and thus emphasized the importance and necessity of guidance law recognition. Recognition of guidance law on non-cooperative vehicle is highly supportive for pursued vehicle to conduct guidance law optimization, guidance law evaluation, and trajectory prediction. Huge variety of design and implementation of guidance law made recognition a hard problem. In this paper, a generic implicit guidance function is proposed to establish unified description of all known guidance laws. A practical model with time-varying guidance parameter is formulated to approximate generic implicit guidance function, and a Kalman Filter based observation data processing algorithm is proposed to build real-time guidance recognition. Simulation results show that, whether the vehicle under pursuit maneuvers or not, the guidance parameters of pursuing vehicle change or not, recognition algorithm can provide reasonable results.

关键词： Vehicles Kalman filters Trajectory Target recognition Target tracking Optimization Chapters

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X-band narrowband high-temperature super-conducting filter with high selectivity

X-band narrowband high-temperature super-conducting filter w...

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IET International Radar Conference 2015

作者： Gao, L. Jiang, Z.Y. Liu, J.Q. Liu, H.Y. Bai, J.L. Xu, F. Li, H. Chen, S.Y. Sun, L. Bian, Y.B. Wang, J. He, Y.S. National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics P.O. Box 9200 Beijing100076 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences P.O. Box 603 Beijing100190 China

ISBN: (纸本)9781785610387

This paper presents a development of a narrowband hightemperature superconducting filter with high selectivity. The center frequency of this filter is 8.625 GHz and the 3 dB bandwidth is 156 MHz (a fractional bandwidth of 1.81 %). In order to achieve high band edge steepness, we introduce a 10-resonator quasi-elliptic function response with two pairs of transmission zeros in the cascaded quadruplet coupling structure. The filter was manufactured on a 2-in-diameter 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a midband insertion loss of 0.58 dB and a return loss better than 16 dB. Band edge steepness reaches over 3.82 dB/MHz at both the high and low frequency edges. The 60 dB rectangle ratio is less than 1.19. The out-of-band rejection is over 60 dB at 17.8 MHz from the 3 dB band edge.

关键词： Magnesia

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