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A method for feature extraction based on SVD and machine learning

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IOP Conference Series: Materials science and Engineering 2019年第5期569卷

作者： Wei Mao Shuxian Huang Xin Liu Hongyan Liu Jiaqi Liu Yi Shu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Institute of Precision Mechatronics and Controls 100076 China Beijing Institute of Long March Vehicle 100076 China

By studying the shortcomings of feature, which extracted from Radar-Cross Section(RCS),using mathematical and statistical method, using the idea of extracting abstract features in image recognition and speech recognition by artificial intelligence for reference[2][3]. This paper explores the possibility of extracting abstract features of target's RCS sequence, and proposes an abstract feature extraction method of RCS sequence based on singular value decomposition(SVD) feature decomposition. Because of the poor interpretability of abstract features, four different machine learning algorithms are used to classify the extracted Abstract features. The experimental results show that the machine learning algorithm can classify different types of spatial objects with high accuracy, which shows that the RCS features of different spatial objects can be characterized by abstract features.

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Revealing energy dependence of quantum defects via two heteronuclear atoms in an optical tweezer

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arXiv 2019年

作者： Wang, Kunpeng He, Xiaodong Gao, Xiang Guo, Ruijun Xu, Peng Zhuang, Jun Li, Runbing Liu, Min Wang, Jin Li, Jiaming Zhan, Mingsheng State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan National Laboratory for Optoelectronics Wuhan430071 China Center for Cold Atom Physics Chinese Academy of Sciences Wuhan430071 China School of Physics University of Chinese Academy of Sciences Beijing100049 China Institute for Theoretical Physics Vienna University of Technology ViennaA-1040 Austria Beijing Computational Science Research Center Beijing100193 China Department of Physics Center for Atomic and Molecular Nanosciences Tsinghua University Beijing100084 China Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Collaborative Innovation Center of Quantum Matter Beijing100084 China

As a physically motivated and computationally simple model for cold atomic and molecular collisions, the multichannel quantum defect theory (MQDT) with frame transformation (FT) formalism provides an analytical treatment of scattering resonances in an arbitrary partial wave between alkali-metal atoms, leading to the experimental observation of p− and d−wave resonances. However, the inconsistency of quantum defects for describing scattering resonances shows up when compared with experiments. Here, with two heteronuclear atoms in the ground state of an optical tweezer, the energy dependence of quantum defects is obviously revealed by comparing the measured s-wave scattering length with the prediction of MQDT-FT. By dividing the quantum defects into energy sensitive and insensitive categories, the inconsistency is ultimately removed while retaining the analytic structure of MQDT-FT. This study represents a significant improvement in the analytical MQDT-FT and demonstrates that a clean two-particle system is valuable to the test of collisional physics. Copyright © 2019, The Authors. All rights reserved.

关键词： Atoms

Optimal verification and fidelity estimation of maximally entangled states

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arXiv 2019年

作者： Zhu, Huangjun Hayashi, Masahito Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Graduate School of Mathematics Nagoya University Nagoya464-8602 Japan Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 Singapore117542 Singapore

We study the verification of maximally entangled states by virtue of the simplest measurement settings: local projective measurements without adaption. We show that optimal protocols are in one-to-one correspondence with complex projective 2-designs constructed from orthonormal bases. Optimal protocols with minimal measurement settings are in one-to-one correspondence with complete sets of mutually unbiased bases. Based on this observation, optimal protocols are constructed explicitly for any local dimension, which can also be applied to estimating the fidelity with the target state and to detecting entanglement. In addition, we show that incomplete sets of mutually unbiased bases are optimal for verifying maximally entangled states when the number of measurement settings is restricted. Moreover, we construct optimal protocols for the adversarial scenario in which state preparation is not trusted. The number of tests has the same scaling behavior as the counterpart for the nonadversarial scenario;the overhead is no more than three times. We also show that the entanglement of the maximally entangled state can be certified with any given significance level using only one test as long as the local dimension is large enough. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum entanglement

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO–Virgo Observing Run

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Physical Review Letters 2021年第24期126卷 241102-241102页

作者： R. Abbott T. D. Abbott S. Abraham F. Acernese K. Ackley A. Adams C. Adams R. X. Adhikari V. B. Adya C. Affeldt D. Agarwal M. Agathos K. Agatsuma N. Aggarwal O. D. Aguiar L. Aiello A. Ain P. Ajith T. Akutsu K. M. Aleman G. Allen A. Allocca P. A. Altin A. Amato S. Anand A. Ananyeva S. B. Anderson W. G. Anderson M. Ando S. V. Angelova S. Ansoldi J. M. Antelis S. Antier S. Appert Koya Arai Koji Arai Y. Arai S. Araki A. Araya M. C. Araya J. S. Areeda M. Arène N. Aritomi N. Arnaud S. M. Aronson H. Asada Y. Asali G. Ashton Y. Aso S. M. Aston P. Astone F. Aubin P. Auclair P. Aufmuth K. AultONeal C. Austin S. Babak F. Badaracco M. K. M. Bader S. Bae Y. Bae A. M. Baer S. Bagnasco Y. Bai L. Baiotti J. Baird R. Bajpai M. Ball G. Ballardin S. W. Ballmer M. Bals A. Balsamo G. Baltus S. Banagiri D. Bankar R. S. Bankar J. C. Barayoga C. Barbieri B. C. Barish D. Barker P. Barneo S. Barnum F. Barone B. Barr L. Barsotti M. Barsuglia D. Barta J. Bartlett M. A. Barton I. Bartos R. Bassiri A. Basti M. Bawaj J. C. Bayley A. C. Baylor M. Bazzan B. Bécsy V. M. Bedakihale M. Bejger I. Belahcene V. Benedetto D. Beniwal M. G. Benjamin T. F. Bennett J. D. Bentley M. BenYaala F. Bergamin B. K. Berger S. Bernuzzi D. Bersanetti A. Bertolini J. Betzwieser R. Bhandare A. V. Bhandari D. Bhattacharjee S. Bhaumik J. Bidler I. A. Bilenko G. Billingsley R. Birney O. Birnholtz S. Biscans M. Bischi S. Biscoveanu A. Bisht B. Biswas M. Bitossi M.-A. Bizouard J. K. Blackburn J. Blackman C. D. Blair D. G. Blair R. M. Blair F. Bobba N. Bode M. Boer G. Bogaert M. Boldrini F. Bondu E. Bonilla R. Bonnand P. Booker B. A. Boom R. Bork V. Boschi N. Bose S. Bose V. Bossilkov V. Boudart Y. Bouffanais A. Bozzi C. Bradaschia P. R. Brady A. Bramley A. Branch M. Branchesi M. Breschi T. Briant J. H. Briggs A. Brillet M. Brinkmann P. Brockill A. F. Brooks J. Brooks D. D. Brown S. Brunett G. Bruno R. Bruntz J. Bryant A. Buikema T. Bulik H. J. Bulten A. Buonanno R. Buscicchio D. Buskulic L. Cadonati M. Caesar G. Cagnoli C. Cahillane H. W. Cain, III J. Calderón Bustillo J. D LIGO Laboratory California Institute of Technology Pasadena California 91125 USA Louisiana State University Baton Rouge Louisiana 70803 USA Inter-University Centre for Astronomy and Astrophysics Pune 411007 India Dipartimento di Farmacia Università di Salerno I-84084 Fisciano Salerno Italy INFN Sezione di Napoli Complesso Universitario di Monte S.Angelo I-80126 Napoli Italy OzGrav School of Physics and Astronomy Monash University Clayton 3800 Victoria Australia Christopher Newport University Newport News Virginia 23606 USA LIGO Livingston Observatory Livingston Louisiana 70754 USA OzGrav Australian National University Canberra Australian Capital Territory 0200 Australia Max Planck Institute for Gravitational Physics (Albert Einstein Institute) D-30167 Hannover Germany Leibniz Universität Hannover D-30167 Hannover Germany University of Cambridge Cambridge CB2 1TN United Kingdom Theoretisch-Physikalisches Institut Friedrich-Schiller-Universität Jena D-07743 Jena Germany University of Birmingham Birmingham B15 2TT United Kingdom Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) Northwestern University Evanston Illinois 60208 USA Instituto Nacional de Pesquisas Espaciais 12227-010 São José dos Campos São Paulo Brazil Gravity Exploration Institute Cardiff University Cardiff CF24 3AA United Kingdom Gran Sasso Science Institute (GSSI) I-67100 L’Aquila Italy INFN Laboratori Nazionali del Gran Sasso I-67100 Assergi Italy INFN Sezione di Pisa I-56127 Pisa Italy Università di Pisa I-56127 Pisa Italy International Centre for Theoretical Sciences Tata Institute of Fundamental Research Bengaluru 560089 India Gravitational Wave Science Project National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan Advanced Technology Center National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan California State University Fullerton Fullerton California 92831 USA NCSA University of Illi

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO–Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10−15. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

关键词： Cosmic strings & domain walls Gravitational waves

The Way from natural to artificial - the story of Periodic Electromagnetic Structures

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The Way from natural to artificial - the story of Periodic E...

International Applied Computational Electromagnetics Society Symposium in China

作者： Shengjun Zhang Mingliang Wang Xia Ai Weidong Wang Runhui Wu Xin Liu Jiaqi Liu Gang Meng Yuan Sun National Key Laboratory of Science & Technology on Test Physics and Numerical Mathematics The Institute of Effectiveness Evaluation of Flying Vehicle

In this paper, the general of artificial electromagnetic structure with analog to the natural materials were briefly reviewed. The lattice theory of artificial structure was suggested to be built.

ISBN: (纸本)9781509043118

In this paper, the general of artificial electromagnetic structure with analog to the natural materials were briefly reviewed. The lattice theory of artificial structure was suggested to be built.

关键词： Artificial structure Electromagnetic lattice Artificial structure lattice theory natural material ELECTROMAGNETIC

The R-Process Alliance: Chemo-Dynamically Tagged Groups of halo r-process-enhanced stars reveal a shared chemical-evolution history

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arXiv 2020年

作者： Gudin, Dmitrii Shank, Derek Beers, Timothy C. Yuan, Zhen Limberg, Guilherme Roederer, Ian U. Placco, Vinicius Holmbeck, Erika M. Dietz, Sarah Rasmussen, Kaitlin C. Hansen, Terese T. Sakari, Charli M. Ezzeddine, Rana Frebel, Anna Department of Physics University of Notre Dame Notre DameIN46556 United States United States Department of Mathematics University of Maryland College ParkMD20742 United States Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Universidade de São Paulo Instituto de Astronomia Geofísica e Ciências Atmosféricas Departamento de Astronomia São Paulo SP05508-090 Brazil Department of Astronomy University of Michigan 1085 S. University Ave. Ann ArborMI48109 United States NSF’s National Optical-Infrared Astronomy Research Laboratory TucsonAZ85719 United States Center for Computational Relativity and Gravitation Rochester Institute of Technology RochesterNY14623 United States George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy Texas A&M University College StationTX77843 United States Department of Physics and Astronomy Texas A&M University College StationTX77843 United States Department of Physics and Astronomy San Francisco State University San FranciscoCA94132 United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States Department of Astronomy University of Florida Bryant Space Science Center GainesvilleFL32611 United States

We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance, supplemented by additional literature samples. This sample represents more than a ten-fold increase in size relative to that previously considered by Roederer et al., and, by design, covers a larger range of r-process-element enrichment levels. We test a number of clustering analysis methods on the derived orbital energies and other dynamical parameters for this sample, ultimately deciding on application of the HDBSCAN algorithm, which obtains 30 individual Chemo-Dynamically Tagged Groups (CDTGs);21 contain between 3 and 5 stars, and 9 contain between 6 and 12 stars. Even though the clustering was performed solely on the basis of their dynamical properties, the stars in these CDTGs exhibit statistically significant similarities in their metallicity ([Fe/H]), carbonicity ([C/Fe]), and neutron-capture element ratios ([Sr/Fe], [Ba/Fe], and [Eu/Fe]). These results demonstrate that the RPE stars in these CDTGs have likely experienced common chemical-evolution histories, presumably in their parent satellite galaxies or globular clusters, prior to being disrupted into the Milky Way’s halo. We also confirm the previous claim that the orbits of the RPE stars preferentially exhibit pericentric distances that are substantially lower than the present distances of surviving ultra-faint dwarf and canonical dwarf spheroidal galaxies, consistent with the disruption hypothesis. The derived dynamical parameters for several of our CDTGs indicate their association with previously known substructures, Dynamically Tagged Groups, and RPE Groups. © 2020, CC BY-NC-ND.

关键词： Galaxies

GRID: A Student Project to Monitor the Transient Gamma-Ray Sky in the Multi-Messenger Astronomy Era

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arXiv 2019年

作者： Wen, Jiaxing Long, Xiangyun Zheng, Xutao An, Yu Cai, Zhengyang Cang, Jirong Che, Yuepeng Chen, Changyu Chen, Liangjun Chen, Qianjun Chen, Ziyun Cheng, Yingjie Deng, Litao Deng, Wei Ding, Wenqing Du, Hangci Duan, Lian Gan, Quan Gao, Tai Gao, Zhiying Han, Wenbin Han, Yiying He, Xinbo He, Xinhao Hou, Long Hu, Fan Hu, Junling Huang, Bo Huang, Dongyang Huang, Xuefeng Jia, Shihai Jiang, Yuchen Jin, Yifei Li, Ke Li, Siyao Li, Yurong Liang, Jianwei Liang, Yuanyuan Lin, Wei Liu, Chang Liu, Gang Liu, Mengyuan Liu, Rui Liu, Tianyu Liu, Wanqiang Lu, Di'an Lu, Peiyibin Lu, Zhiyong Luo, Xiyu Ma, Sizheng Ma, Yuanhang Mao, Xiaoqing Mo, Yanshan Nie, Qiyuan Qu, Shuiyin Shan, Xiaolong Shi, Gengyuan Song, Weiming Sun, Zhigang Tan, Xuelin Tang, Songsong Tao, Mingrui Wang, Boqin Wang, Yue Wang, Zhiang Wu, Qiaoya Wu, Xuanyi Xia, Yuehan Xiao, Hengyuan Xie, Wenjin Xu, Dacheng Xu, Rui Xu, Weili Yan, Longbiao Yan, Shengyu Yang, Dongxin Yang, Hang Yang, Haoguang Yang, Yi-Si Yang, Yifan Yao, Lei Yu, Huan Yu, Yangyi Zhang, Aiqiang Zhang, Bingtao Zhang, Lixuan Zhang, Maoxing Zhang, Shen Zhang, Tianliang Zhang, Yuchong Zhao, Qianru Zhao, Ruining Zheng, Shiyu Zhou, Xiaolong Zhu, Runyu Zou, Yu An, Peng Cai, Yifu Chen, Hongbing Dai, Zigao Fan, Yizhong Feng, Changqing Feng, Hua Gao, He Huang, Liang Kang, Mingming Li, Lixin Li, Zhuo Liang, Enwei Lin, Lin Lin, Qianqian Liu, Congzhan Liu, Hongbang Liu, Xuewen Liu, Yinong Lu, Xiang Mao, Shude Shen, Rongfeng Shu, Jing Su, Meng Sun, Hui Tam, Pak-Hin Tang, Chi-Pui Tian, Yang Wang, Fayin Wang, Jianjun Wang, Wei Wang, Zhonghai Wu, Jianfeng Wu, Xuefeng Xiong, Shaolin Xu, Can Yu, Jiandong Yu, Wenfei Yu, Yunwei Zeng, Ming Zeng, Zhi Zhang, Bin-Bin Zhang, Bing Zhao, Zongqing Zhou, Rong Zhu, Zonghong Department of Engineering Physics Center for Astrophysics Tsinghua University Beijing100084 China Science and Technology on Plasma Physics Laboratory Laser Fusion Research Center Chinese Academy of Engineering Physics Mianyang621900 China Department of Physics Center for Astrophysics Tsinghua University Beijing100084 China Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University NanningGuangxi530004 China School of Electronic and Information Engineering Ningbo University of Technology NingboZhejiang315211 China Department of Instruments Science & Engineering Shanghai Jiaotong University Shanghai200240 · China School of Materials Science & Chemical Engineering Ningbo University Ningbo315211 China School of Astronomy and Space Science Nanjing University NanjingJiangsu210093 China School of Aerospace Engineering Tsinghua University Beijing100084 China College of Physical Science and Technology Sichuan University Chengdu610065 China School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China Department of Astronomy Xiamen University XiamenFujian361005 China School of Mathematics and Physics University of Science and Technology Beijing Beijing100083 China Department of Foreign Languages and Literatures Tsinghua University Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China School of Software Tsinghua University Beijing100084 China Faculty of Electrical Engineering and Computer Science Ningbo University Ningbo315211 China Department of Modern Physics School of Physical Sciences University of Science and Technology of China HefeiAnhui230026 China Department of Astronomy Beijing Normal University Beijing100875 China Department of Astronomy School of Physical Sciences University of Science and Technology of China HefeiAnhui230026 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China Department of Astrono

The Gamma-Ray Integrated Detectors (GRID) is a space mission concept dedicated to monitoring the transient gamma-ray sky in the energy range from 10 keV to 2 MeV using scintillation detectors onboard CubeSats in low Earth orbits. The primary targets of GRID are the gamma-ray bursts (GRBs) in the local universe. The scientific goal of GRID is, in synergy with ground-based gravitational wave (GW) detectors such as LIGO and VIRGO, to accumulate a sample of GRBs associated with the merger of two compact stars and study jets and related physics of those objects. It also involves observing and studying other gamma-ray transients such as long GRBs, soft gamma-ray repeaters, terrestrial gamma-ray flashes, and solar flares. With multiple CubeSats in various orbits, GRID is unaffected by the Earth occultation and serves as a full-time and all-sky monitor. Assuming a horizon of 200 Mpc for ground-based GW detectors, we expect to see a few associated GW-GRB events per year. With about 10 CubeSats in operation, GRID is capable of localizing a faint GRB like 170817A with a 90% error radius of about 10 degrees, through triangulation and flux modulation. GRID is proposed and developed by students, with considerable contribution from undergraduate students, and will remain operated as a student project in the future. The current GRID collaboration involves more than 20 institutes and keeps growing. On August 29th, the first GRID detector onboard a CubeSat was launched into a Sun-synchronous orbit and is currently under test. Copyright © 2019, The Authors. All rights reserved.

关键词： Gravity waves

Search for anisotropic gravitational-wave backgrounds using data from Advanced LIGO and Advanced Virgo’s first three observing runs

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Physical Review D 2021年第2期104卷 022005-022005页

作者： R. Abbott T. D. Abbott S. Abraham F. Acernese K. Ackley A. Adams C. Adams R. X. Adhikari V. B. Adya C. Affeldt D. Agarwal M. Agathos K. Agatsuma N. Aggarwal O. D. Aguiar L. Aiello A. Ain P. Ajith T. Akutsu K. M. Aleman G. Allen A. Allocca P. A. Altin A. Amato S. Anand A. Ananyeva S. B. Anderson W. G. Anderson M. Ando S. V. Angelova S. Ansoldi J. M. Antelis S. Antier S. Appert Koya Arai Koji Arai Y. Arai S. Araki A. Araya M. C. Araya J. S. Areeda M. Arène N. Aritomi N. Arnaud S. M. Aronson H. Asada Y. Asali G. Ashton Y. Aso S. M. Aston P. Astone F. Aubin P. Aufmuth K. AultONeal C. Austin S. Babak F. Badaracco M. K. M. Bader S. Bae Y. Bae A. M. Baer S. Bagnasco Y. Bai L. Baiotti J. Baird R. Bajpai M. Ball G. Ballardin S. W. Ballmer M. Bals A. Balsamo G. Baltus S. Banagiri D. Bankar R. S. Bankar J. C. Barayoga C. Barbieri B. C. Barish D. Barker P. Barneo F. Barone B. Barr L. Barsotti M. Barsuglia D. Barta J. Bartlett M. A. Barton I. Bartos R. Bassiri A. Basti M. Bawaj J. C. Bayley A. C. Baylor M. Bazzan B. Bécsy V. M. Bedakihale M. Bejger I. Belahcene V. Benedetto D. Beniwal M. G. Benjamin T. F. Bennett J. D. Bentley M. BenYaala F. Bergamin B. K. Berger S. Bernuzzi D. Bersanetti A. Bertolini J. Betzwieser R. Bhandare A. V. Bhandari D. Bhattacharjee S. Bhaumik J. Bidler I. A. Bilenko G. Billingsley R. Birney O. Birnholtz S. Biscans M. Bischi S. Biscoveanu A. Bisht B. Biswas M. Bitossi M.-A. Bizouard J. K. Blackburn J. Blackman C. D. Blair D. G. Blair R. M. Blair F. Bobba N. Bode M. Boer G. Bogaert M. Boldrini F. Bondu E. Bonilla R. Bonnand P. Booker B. A. Boom R. Bork V. Boschi N. Bose S. Bose V. Bossilkov V. Boudart Y. Bouffanais A. Bozzi C. Bradaschia P. R. Brady A. Bramley A. Branch M. Branchesi J. E. Brau M. Breschi T. Briant J. H. Briggs A. Brillet M. Brinkmann P. Brockill A. F. Brooks J. Brooks D. D. Brown S. Brunett G. Bruno R. Bruntz J. Bryant A. Buikema T. Bulik H. J. Bulten A. Buonanno R. Buscicchio D. Buskulic R. L. Byer L. Cadonati M. Caesar G. Cagnoli C. Cahillane H. W. Cain, III J. Calderón Bustillo J. LIGO Laboratory California Institute of Technology Pasadena California 91125 USA Louisiana State University Baton Rouge Louisiana 70803 USA Inter-University Centre for Astronomy and Astrophysics Pune 411007 India Dipartimento di Farmacia Università di Salerno I-84084 Fisciano Salerno Italy INFN Sezione di Napoli Complesso Universitario di Monte S.Angelo I-80126 Napoli Italy OzGrav School of Physics & Astronomy Monash University Clayton 3800 Victoria Australia Christopher Newport University Newport News Virginia 23606 USA LIGO Livingston Observatory Livingston Louisiana 70754 USA OzGrav Australian National University Canberra Australian Capital Territory 0200 Australia Max Planck Institute for Gravitational Physics (Albert Einstein Institute) D-30167 Hannover Germany Leibniz Universität Hannover D-30167 Hannover Germany University of Cambridge Cambridge CB2 1TN United Kingdom Theoretisch-Physikalisches Institut Friedrich-Schiller-Universität Jena D-07743 Jena Germany University of Birmingham Birmingham B15 2TT United Kingdom Center for Interdisciplinary Exploration & Research in Astrophysics (CIERA) Northwestern University Evanston Illinois 60208 USA Instituto Nacional de Pesquisas Espaciais 12227-010 São José dos Campos São Paulo Brazil Gravity Exploration Institute Cardiff University Cardiff CF24 3AA United Kingdom Gran Sasso Science Institute (GSSI) I-67100 L’Aquila Italy INFN Laboratori Nazionali del Gran Sasso I-67100 Assergi Italy INFN Sezione di Pisa I-56127 Pisa Italy Università di Pisa I-56127 Pisa Italy International Centre for Theoretical Sciences Tata Institute of Fundamental Research Bengaluru 560089 India Gravitational Wave Science Project National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan Advanced Technology Center National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan California State University Fullerton Fullerton California 92831 USA NCSA University of Illinois

We report results from searches for anisotropic stochastic gravitational-wave backgrounds using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. For the first time, we include Virgo data in our analysis and run our search with a new efficient pipeline called pystoch on data folded over one sidereal day. We use gravitational-wave radiometry (broadband and narrow band) to produce sky maps of stochastic gravitational-wave backgrounds and to search for gravitational waves from point sources. A spherical harmonic decomposition method is employed to look for gravitational-wave emission from spatially-extended sources. Neither technique found evidence of gravitational-wave signals. Hence we derive 95% confidence-level upper limit sky maps on the gravitational-wave energy flux from broadband point sources, ranging from Fα,Θ<(0.013–7.6)×10−8 erg cm−2 s−1 Hz−1, and on the (normalized) gravitational-wave energy density spectrum from extended sources, ranging from Ωα,Θ<(0.57–9.3)×10−9 sr−1, depending on direction (Θ) and spectral index (α). These limits improve upon previous limits by factors of 2.9–3.5. We also set 95% confidence level upper limits on the frequency-dependent strain amplitudes of quasimonochromatic gravitational waves coming from three interesting targets, Scorpius X-1, SN 1987A and the Galactic Center, with best upper limits range from h0<(1.7–2.1)×10−25, a factor of ≥2.0 improvement compared to previous stochastic radiometer searches.

关键词： Experimental studies of gravity General relativity Gravitational waves

Study of RF structure and Beam Wave Interaction system for a W-band Sheet Beam EIK

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Study of RF structure and Beam Wave Interaction system for a...

International Conference on Radar Systems

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

ISBN: (纸本)9781785616723

Sheet beam Extended Interaction Klystron (EIK) is an attractive Millimeter Waves (MMW) amplifier because of its high gain per unit length and compact configuration, which can be used in radar transmission system. In this paper, RF structure and beam wave interaction system of W band sheet beam EIK has been designed. A new and effective method of designing and studying the beam wave interaction system is presented in this paper. The whole tube consists of one single-gap cavity, six tri-gaps cavities and one five-gaps cavity. By optimizing the position of cavities, the output power can achieve 30 kW and high gain of 50 dB, which is calculated by three dimensional particle in cell (3D-PIC) software. It provides a powerful basis for the subsequent study of sheet beam EIK.

关键词： RF EIK Dumbbell cavity Interaction system