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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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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： 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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The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project

arXiv

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arXiv 2019年

作者： Porth, Oliver Chatterjee, Koushik Narayan, Ramesh Gammie, Charles F. Mizuno, Yosuke Anninos, Peter Baker, John G. Bugli, Matteo Chan, Chi-Kwan Davelaar, Jordy Zanna, Luca Del Etienne, Zachariah B. Fragile, P. Chris Kelly, Bernard J. Liska, Matthew Markoff, Sera McKinney, Jonathan C. Mishra, Bhupendra Noble, Scott C. Olivares, Héctor Prather, Ben Rezzolla, Luciano Ryan, Benjamin R. Stone, James M. Tomei, Niccolò White, Christopher J. Younsi, Ziri Akiyama, Kazunori Alberdi, Antxon Alef, Walter Asada, Keiichi Azulay, Rebecca Baczko, Anne-Kathrin Ball, David Baloković, Mislav Barrett, John Bintley, Dan Blackburn, Lindy Boland, Wilfred Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brinkerink, Christiaan D. Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Byun, Do-Young Carlstrom, John E. Chael, Andrew Chatterjee, Shami Chen, Ming-Tang Chen, Yongjun Cho, Ilje Christian, Pierre Conway, John E. Cordes, James M. Crew, Geoffrey B. Cui, Yuzhu Laurentis, Mariafelicia De Deane, Roger Dempsey, Jessica Desvignes, Gregory Doeleman, Sheperd S. Eatough, Ralph P. Falcke, Heino Fish, Vincent L. Fomalont, Ed Fraga-Encinas, Raquel Freeman, Bill Friberg, Per Fromm, Christian M. Gómez, José L. Galison, Peter García, Roberto Gentaz, Olivier Georgiev, Boris Goddi, Ciriaco Gold, Roman Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Hecht, Michael H. Hesper, Ronald Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Hughes, David H. Ikeda, Shiro Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Johnson, Michael D. Jorstad, Svetlana Jung, Taehyun Karami, Mansour Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Jae-Young Kim, Junhan Kim, Jongsoo Kino, Motoki Koay, Jun Y.I. Koch, Patrick M. Koyama, Shoko Kramer, Michael Kramer, Carsten Krichbaum, Thomas P. Kuo, Cheng-Yu Lauer, Tod R. Lee, Sang-Sung Li, Yan-Rong Li, Zhiyuan Lindqvist, Michael Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Lau Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Institut für Theoretische Physik Goethe-Universität Frankfurt Max-von-Laue-Straße 1 Frankfurt am MainD-60438 Germany Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Black Hole Initiative at Harvard University 20 Garden Street CambridgeMA02138 United States Department of Astronomy Department of Physics University of Illinois UrbanaIL61801 United States Lawrence Livermore National Laboratory LivermoreCA94550 United States Gravitational Astrophysics Laboratory NASA Goddard Space Flight Center GreenbeltMD20771 United States Joint Space-Science Institute University of Maryland College ParkMD20742 United States IRFU Département d’Astrophysique Laboratoire AIM CEA/DRF-CNRS-Université Paris Diderot CEA-Saclay F-91191 France Steward Observatory and Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Radboud University P.O. Box 9010 Nijmegen6500 GL Netherlands Dipartimento di Fisica e Astronomia Università di Firenze e INFN – Sez. di Firenze via G. Sansone 1 Sesto F.noI-50019 Italy INAF Osservatorio Astrofisico di Arcetri Largo E. Fermi 5 FirenzeI-50125 Italy Department of Mathematics West Virginia University MorgantownWV26506 United States Center for Gravitational Waves and Cosmology West Virginia University Chestnut Ridge Research Building MorgantownWV26505 United States Department of Physics & Astronomy College of Charleston 66 George St. CharlestonSC29424 United States Department of Physics University of Maryland Baltimore County BaltimoreMD21250 United States CRESST NASA Goddard Space Flight Center GreenbeltMD20771 United States Anton Pannekoek Institute for Astronomy & GRAPPA University of Amsterdam Postbus 94249 Amsterdam1090G

Recent developments in compact object astrophysics, especially the discovery of merging neutron stars by LIGO, the imaging of the black hole in M87 by the Event Horizon Telescope (EHT) and high precision astrometry of the Galactic Center at close to the event horizon scale by the GRAVITY experiment motivate the development of numerical source models that solve the equations of general relativistic magnetohydrodynamics (GRMHD). Here we compare GRMHD solutions for the evolution of a magnetized accretion flow where turbulence is promoted by the magnetorotational instability from a set of nine GRMHD codes: Athena++, BHAC, Cosmos++, ECHO, H-AMR, iharm3D, HARM-Noble, IllinoisGRMHD and KORAL. Agreement between the codes improves as resolution increases, as measured by a consistently applied, specially developed set of code performance metrics. We conclude that the community of GRMHD codes is mature, capable, and consistent on these test problems. Copyright © 2019, The Authors. All rights reserved.

关键词： Magnetohydrodynamics

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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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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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Evaluation of the interplanetary magnetic field strength using the cosmic-ray shadow of the sun

arXiv

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arXiv 2018年

作者： Amenomori, M. Bi, X.J. Chen, D. Chen, T.L. Chen, W.Y. Cui, S.W. Danzengluobu Ding, L.K. Feng, C.F. Feng, Zhaoyang Feng, Z.Y. Gou, Q.B. Guo, Y.Q. He, H.H. He, Z.T. Hibino, K. Hotta, N. Hu, Haibing Hu, H.B. Huang, J. Jia, H.Y. Jiang, L. Kajino, F. Kasahara, K. Katayose, Y. Kato, C. Kawata, K. Kozai, M. Labaciren Le, G.M. Li, A.F. Li, H.J. Li, W.J. Liu, C. Liu, J.S. Liu, M.Y. Lu, H. Meng, X.R. Miyazaki, T. Mizutani, K. Munakata, K. Nakajima, T. Nakamura, Y. Nanjo, H. Nishizawa, M. Niwa, T. Ohnishi, M. Ohta, I. Ozawa, S. Qian, X.L. Qu, X.B. Saito, T. Saito, T.Y. Sakata, M. Sako, T.K. Shao, J. Shibata, M. Shiomi, A. Shirai, T. Sugimoto, H. Takita, M. Tan, Y.H. Tateyama, N. Torii, S. Tsuchiya, H. Udo, S. Wang, H. Wu, H.R. Xue, L. Yamamoto, Y. Yamauchi, K. Yang, Z. Yuan, A.F. Yuda, T. Zhai, L.M. Zhang, H.M. Zhang, J.L. Zhang, X.Y. Zhang, Y. Zhang, Yi Zhang, Ying Zhaxisangzhu Zhou, X.X. Department of Physics Hirosaki University Hirosaki036-8561 Japan Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China Department of Mathematics and Physics Tibet University Lhasa850000 China Department of Physics Hebei Normal University Shijiazhuang050016 China Department of Physics Shandong University Jinan250100 China Institute of Modern Physics SouthWest Jiaotong University Chengdu610031 China Faculty of Engineering Kanagawa University Yokohama221-8686 Japan Faculty of Education Utsunomiya University Utsunomiya321-8505 Japan Department of Physics Konan University Kobe658-8501 Japan Research Institute for Science and Engineering Waseda University Tokyo169-8555 Japan Faculty of Engineering Yokohama National University Yokohama240-8501 Japan Department of Physics Shinshu University Matsumoto390-8621 Japan Institute for Cosmic Ray Research University of Tokyo Kashiwa277-8582 Japan Sagamihara Kanagawa252-5210 Japan National Center for Space Weather China Meteorological Administration Beijing100081 China School of Information Science and Engineering Shandong Agriculture University Taian271018 China Saitama University Saitama338-8570 Japan National Institute of Informatics Tokyo101-8430 Japan Sakushin Gakuin University Utsunomiya321-3295 Japan College of Science China University of Petroleum Qingdao266555 China Tokyo Metropolitan College of Industrial Technology Tokyo116-8523 Japan Max-Planck-Institut für Physik MünchenD-80805 Germany Escuela de Ciencias Físicas y Nanotechnología Yachay Tech Imbabura100115 Ecuador College of Industrial Technology Nihon University Narashino275-8576 Japan Shonan Institute of Technology Fujisawa251-8511 Japan Japan Atomic Energy Agency Tokai-mura319-1195 Japan

We analyze the Sun’s shadow observed with the Tibet-III air shower array and find that the shadow’s center deviates northward (southward) from the optical solar disc center in the "Away" ("Toward") IMF sector. By comparing with numerical simulations based on the solar magnetic field model, we find that the average IMF strength in the "Away" ("Toward") sector is 1.54 ± 0.21stat ± 0.20syst (1.62±0.15stat±0.22syst) times larger than the model prediction. These demonstrate that the observed Sun’s shadow is a useful tool for the quantitative evaluation of the average solar magnetic field. Copyright © 2018, The Authors. All rights reserved.

关键词： Cosmic rays

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Modified k-ω model using kinematic vorticity for corner separation in compressor cascades

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science China(Technological sciences) 2016年第5期59卷 795-806页

作者： LIU YangWei YAN Hao FANG Le LULiPeng LI QiuShi SHAO Liang National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power Engineering Beihang University Beijing 100191 China Collaborative Innovation Center of Advanced Aero-Engine Beihang University Beijing 100191 China Laboratory of Mathematics and Physics Ecole Centrale de Pekin Beihang University Beijing 100191 China Laboratoire de Mecanique ties Fluides et d'Acoustique Ecole Centrale de Lyon Ecullv 69134 France

A new method of modifying the conventional k-w turbulence model for comer separation is proposed in this paper. The production term in the w equation is modified using kinematic vorticity considering fluid rotation and deformation in complex geometric boundary conditions. The corner separation flow in linear compressor cascades is calculated using the original k-w model, the modified k-w model and the Reynolds stress model （RSM）. The numerical results of the modified model are compared with the available experimental data, as well as the corresponding results of the original k-w model and RSM. In terms of accuracy, the modified model, which significantly improves the performance of the original k-w model for predicting comer separation, is quite competitive with the RSM. However, the modified model, which has considerably lower computational cost is more robust than the RSM.

关键词： k-w comodel kinematic vorticity corner separation compressor cascades

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