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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

引用

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

引用

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

引用

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

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

引用

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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Quantum gate identification: Error analysis, numerical results and optical experiment?

arXiv

引用

arXiv 2017年

作者： Wang, Yuanlong Yin, Qi Dong, Daoyi Qi, Bo Petersen, Ian R. Hou, Zhibo Yonezawa, Hidehiro Xiang, Guo-Yong School of Engineering and Information Technology University of New South Wales CanberraACT2600 Australia Centre for Quantum Computation and Communication Technology Australian Research Council CanberraACT2600 Australia Key Laboratory of Quantum Information University of Science and Technology of China CAS Hefei230026 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui230026 China Key Laboratory of Systems and Control Academy of Mathematics and Systems Science CAS Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Research School of Engineering Australian National University CanberraACT0200 Australia

The identification of an unknown quantum gate is a significant issue in quantum technology. In this paper, we propose a quantum gate identification method within the framework of quantum process tomography. In this method, a series of pure states are inputted to the gate and then a fast state tomography on the output states is performed and the data are used to reconstruct the quantum gate. Our algorithm has computational complexity O(d3) with the system dimension d. The algorithm is compared with maximum likelihood estimation method for the running time, which shows the efficiency advantage of our method. An error upper bound is established for the identification algorithm and the robustness of the algorithm against the purity of input states is also tested. We perform quantum optical experiment on single-qubit Hadamard gate to verify the effectiveness of the identification algorithm. Copyright © 2017, The Authors. All rights reserved.

关键词： Computational complexity

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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

引用

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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classification for a novel antiferromagnetic topological insulating phase in three-dimensional topological Kondo insulator

引用

Journal of physics: Condensed Matter 2018年第43期30卷

作者： Huan Li Yin Zhong Yu Liu Hong-Gang Luo Hai-Feng Song College of Science Guilin University of Technology Guilin 541004 People's Republic of China Author to whom any correspondence should be addressed. Center for Interdisciplinary Studies & Key Laboratory for Magnetism and Magnetic Materials of the MoE Lanzhou University Lanzhou 730000 People's Republic of China Institute of Applied Physics and Computational Mathematics Beijing 100088 People's Republic of China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing 100088 People's Republic of China Beijing Computational Science Research Center Beijing 100084 People's Republic of China

Antiferromagnetic topological insulator (AFTI) is a topological matter that breaks time-reversal symmetry. Since its proposal, explorations of AFTI in strong-correlated systems are still lacking. In this paper, we show for the first time that a novel AFTI phase can be realized in three-dimensional topological Kondo insulator (TKI). In a wide parameter region, the ground states of TKI undergo a second-order transition to antiferromagnetic insulating phases which conserve a combined symmetry of time reversal and a lattice translation, allowing us to derive a -classification formula for these states. By calculating the index, the antiferromagnetic insulating states are classified into AFTI or non-topological antiferromagnetic insulator (nAFI) in different parameter regions. On the antiferromagnetic surfaces in AFTI, we find topologically protected gapless Dirac cones inside the bulk gap, leading to metallic Fermi rings exhibiting helical spin texture with weak spin-momentum locking. Depending on model parameters, the magnetic transitions take place either between AFTI and strong topological insulator, or between nAFI and weak topological insulator. By varying some model parameters, we find a topological transition between AFTI and nAFI, driving by closing of bulk gap. Our work may account for the pressure-induced magnetism in TKI compound SmB6, and helps to explore richer AFTI phases in heavy-fermion systems as well as in other strong-correlated systems.

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