检索结果-内蒙古大学图书馆

IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Feng Xue Hanjie Pan Runhui Wu Xin Liu Jiaqi Liu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 China Audiovisual Communications Laboratory School of Computer and Communication Sciences Ecole Polytechnique Federale de Lausanne (EPFL) Switzerland

ISBN: (纸本)9781509041183

Recently, the type of compound regularizers has become a popular choice for signal reconstruction. The estimation quality is generally sensitive to the values of multiple regularization parameters. In this work, based on BDF algorithm, we develop a data-driven optimization scheme based on minimization of Stein's unbiased risk estimate (SURE) - statistically equivalent to mean squared error (MSE). We propose a recursive evaluation of SURE to monitor the MSE during BDF iteration;the optimal values of the multiple parameters are then identified by the minimum SURE. Monte-Carlo simulation is applied to compute SURE for large-scale data. We exemplify the proposed method with image deconvolution. numerical experiments show that the proposed method leads to highly accurate estimates of regularization parameters and nearly optimal restoration performance.

关键词： Stein's unbiased risk estimate (SURE) compound regularizers regularization parameter BDF algorithm signal deconvolution Risk estimation Mean square error BDF unbiasedness Signal reconstruction parameters compounds highly accurate

来源：评论

学校读者我要写书评

暂无评论

Rho-pion transition form factors in the kT factorization formulism revisited

arXiv

引用

arXiv 2018年

作者： Hua, Jun Cheng, Shan Zhang, Ya-Lan Xiao, Zhen-Jun Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu210023 China School of Physics and Microelectronics Science Hunan University Changsha Hunan410082 China Department of Faculty of Mathematics and Physics Huaiyin Institute of Technology Huaian Jiangsu223001 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu210023 China

We revisit the evaluations for the spacelike and timelike ρπ transition form factors Fρπ(Q2) and Gρπ(Q2) with the inclusion of the the next-to-leading order (NLO) QCD contributions in the framework of the kT factorization theorem. The infrared divergence is regularized by the transversal momentum carried by external valence quarks, and ultimately absorbed into the meson wave functions. In the region of Q2 6 2 GeV2, where PQCD factorization apporach applicable, the NLO contribution can bring no larger than 35% enhancement to the spacelike form factor Fρπ(Q2). For the timelike form factor derived under the kinematic exchanging symmetry, this contribution is also under control when the momentum transfer squared is large enough. We also prolong our prediction into the small Q2 region by taking the Lattice QCD results into account, and subsequently obtain the coupling gρπγ = Gρπ(0) = 0.596. Copyright © 2018, The Authors. All rights reserved.

关键词： Approximation theory

来源：评论

学校读者我要写书评

暂无评论

SMALL spacecraft: Rules and frames should be built from space security aspect 68

SMALL spacecraft: Rules and frames should be built from spac...

引用

68th International Astronautical Congress: Unlocking Imagination, Fostering Innovation and Strengthening Security, IAC 2017

作者： Zhang, Shengjun Sun, Yuan Xue, Hui Qin, Lihua Liu, Jiaqi Liu, Xin Mu, Lei Wang, Weidong Wang, Mingliang Ai, Xia National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing PO Box 9200-76-6 Beijing100076 China Academy of Launch Vehicle Technology Beijing China Institute of Survival Technology and Effectiveness Evaluation of Flying Vehicle No. 109 Beiqing Road Haidian District Beijing100093 China Beijing Institute of system engineering No. 109 Beiqing Road Haidian District Beijing100101 China

ISBN: (纸本)9781510855373

It has entering an age of small aerospace. New topics have been booming, such small satellite and cubesat, launcher for the small ones and commercial space, which are noticed not only by commercial groups but by the governments. More and more activities are taking place about these small spacecraft, India delivered about 100 cubesat during a launch this year, a small satellite was ejected from Small Satellite Orbital Deployer on the International Space Station in 2016, Some cubesats and small satellite from academical groups from Europe and China and other countries have been launched during other activities. While small spacecraft is benefit for its lower weight, lower cost, short R&D duration, and useful for scientific research, earth observation, and circumstance surveillance, satellite repairing, etc., there are more and more risks with the high speed delivering of manmade objects in low orbits. And in addition, with the development of small launch vehicles, the launching itself maybe executed by anyone themselves in the future. So there should be some new rules and frames built for activities and use of space from the aspect of space security, and which is benefit for the sustainable use of lower orbit and space, and thus for our mankind. Copyright © 2017 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Orbits

来源：评论

学校读者我要写书评

暂无评论

Astrophysics with the Laser Interferometer Space Antenna

arXiv

引用

arXiv 2022年

作者： Amaro Seoane, Pau Andrews, Jeff Arca Sedda, Manuel Askar, Abbas Baghi, Quentin Balasov, Razvan Bartos, Imre Bavera, Simone S. Bellovary, Jillian Berry, Christopher P.L. Berti, Emanuele Bianchi, Stefano Blecha, Laura Steṕhane, Blondin Bogdanović, Tamara Boissier, Samuel Bonetti, Matteo Bonoli, Silvia Bortolas, Elisa Breivik, Katelyn Capelo, Pedro R. Caramete, Laurentiu Cattorini, Federico Charisi, Maria Chaty, Sylvain Chen, Xian Chruślińska, Martyna Chua, Alvin J.K. Church, Ross Colpi, Monica D’Orazio, Daniel Danielski, Camilla Davies, Melvyn B. Dayal, Pratika De Rosa, Alessandra Derdzinski, Andrea Destounis, Kyriakos Dotti, Massimo Duţan, Ioana Dvorkin, Irina Fabj, Gaia Foglizzo, Thierry Ford, Saavik Fouvry, Jean-Baptiste Franchini, Alessia Fragos, Tassos Fryer, Chris Gaspari, Massimo Gerosa, Davide Graziani, Luca Groot, Paul Habouzit, Melanie Haggard, Daryl Haiman, Zoltan Han, Wen-Biao Istrate, Alina Johansson, Peter H. Khan, Fazeel Mahmood Kimpson, Tomas Kokkotas, Kostas Kong, Albert Korol, Valeriya Kremer, Kyle Kupfer, Thomas Lamberts, Astrid Larson, Shane Lau, Mike Liu, Dongliang Lloyd-Ronning, Nicole Lodato, Giuseppe Lupi, Alessandro Ma, Chung-Pei Maccarone, Tomas Mandel, Ilya Mangiagli, Alberto Mapelli, Michela Mathis, Stéphane Mayer, Lucio McGee, Sean McKernan, Berry Miller, M. Coleman Mota, David F. Mumpower, Matthew Nasim, Syeda S. Nelemans, Gijs Noble, Scott Pacucci, Fabio Panessa, Francesca Paschalidis, Vasileios Pfister, Hugo Porquet, Delphine Quenby, John Ricarte, Angelo Röpke, Friedrich K. Regan, John Rosswog, Stephan Institute of Multidisciplinary Mathematics Universitat Politécnica de Valéncia Spain Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Province School of Physical Science and Technology Lanzhou University Lanzhou730000 China Institute of Theoretical Physics Research Center of Gravitation Lanzhou University Lanzhou730000 China Kavli Institute for Astronomy and Astrophysics Beijing China Department of Physics and Astronomy Northwestern University 1800 Sherman Ave EvanstonIL60201 United States Astronomisches Rechen Instituy University of Heidelberg Germany Lund Observatory Department of Astronomy and Theoretical Physics Lund University Box 43 LundSE-221 00 Sweden IRFU CEA Université Paris-Saclay Gif-sur-YvetteF-91191 France Institute of Space Science Magurele Romania Faculty of Physics University of Bucharest Romania Department of Physics University of Florida PO Box 118440 GainesvilleFL32611-8440 United States Geneva Observatory University of Geneva Chemin Pegasi 51 Versoix1290 Switzerland Université de Genève GenevaCH1211 Switzerland CUNY - Queensborough Community College American Museum of Natural History CUNY Graduate Center United States SUPA School of Physics and Astronomy University of Glasgow Kelvin Building University Ave GlasgowG12 8QQ United Kingdom Johns Hopkins University United States Dipartimento di Matematica e Fisica Università degli Studi Roma Tre via della Vasca Navale 84 RomaI-00146 Italy Department of Physics University of Florida United States Aix Marseille Univ CNRS CNES LAM Marseille France School of Physics Center for Relativistic Astrophysics Georgia Institute of Technology 837 State St NW AtlantaGA30332 United States Dipartimento di Fisica "G. Occhialini" Università degli Studi di Milano-Bicocca Piazza della Scienza 3 MilanoI-20126 Italy Paseo Manuel de Lardizabal 4 Donostia-San Sebastian20018 Spain IKERBASQUE Basque Foundation for Science BilbaoE-48013 S

The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and space-born instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA’s first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed;ultra-compact stellar-mass binaries, massive black hole binaries, and extreme or interme-diate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help making progress in the different areas. New research avenues that LISA itself, or its joint exploitation with upcoming studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe. Copyright © 2022, The Authors. All rights reserved.

关键词： Gravity waves

来源：评论

学校读者我要写书评

暂无评论

Rho-pion transition form factors in the kT-factorization formalism revisited

引用

Physical Review D 2018年第11期97卷 113002-113002页

作者： Jun Hua Shan Cheng Ya-lan Zhang Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China School of Physics and Microelectronics Science Hunan University Changsha Hunan 410082 People’s Republic of China Department of Faculty of Mathematics and Physics Huaiyin Institute of Technology Huaian Jiangsu 223001 People’s Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu 210023 People’s Republic of China

We revisit the evaluations for the spacelike and timelike ρπ transition form factors Fρπ(Q2) and Gρπ(Q2) with the inclusion of the next-to-leading order (NLO) QCD contributions in the framework of the kT-factorization theorem. The infrared divergence is regularized by the transversal momentum carried by external valence quarks, and ultimately absorbed into the meson wave functions. In the region of Q2≤2 GeV2, where the perturbative QCD factorization approach is applicable, the NLO contribution can bring no larger than 35% enhancement to the spacelike form factor Fρπ(Q2). For the timelike form factor derived under the kinematic exchanging symmetry, this contribution is also under control when the momentum transfer squared is large enough. We also prolong our prediction into the small Q2 region by taking the lattice QCD results into account, and subsequently obtain the coupling gρπγ=Gρπ(0)=0.596.

关键词： Form factors

来源：评论

学校读者我要写书评

暂无评论

Z2classification for a novel antiferromagnetic topological insulating phase in three-dimensional topological Kondo insulator

arXiv

引用

arXiv 2018年

作者： Li, Huan Zhong, Yin Liu, Yu Luo, Hong-Gang Song, Hai-Feng College of Science Guilin University of Technology Guilin541004 China Center for Interdisciplinary Studies Key Laboratory for Magnetism and Magnetic Materials of the MoE Lanzhou University Lanzhou730000 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Beijing100088 China Beijing Computational Science Research Center Beijing100084 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 Z2-classification formula for these states. By calculating the Z2index, 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 heavyfermion systems as well as in other strong-correlated systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Antiferromagnetism

来源：评论

学校读者我要写书评

暂无评论

Upper limits on the isotropic gravitational-wave background from Advanced LIGO and Advanced Virgo’s third observing run

引用

Physical Review D 2021年第2期104卷 022004-022004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 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 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 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 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 at Urbana-Champaign Urbana Illinois 61801 USA Università di Napoli “Federico II” Complesso Universitario

We report results of a search for an isotropic gravitational-wave background (GWB) using data from Advanced LIGO’s and Advanced Virgo’s third observing run (O3) combined with upper limits from the earlier O1 and O2 runs. Unlike in previous observing runs in the advanced detector era, we include Virgo in the search for the GWB. The results of the search are consistent with uncorrelated noise, and therefore we place upper limits on the strength of the GWB. We find that the dimensionless energy density ΩGW≤5.8×10−9 at the 95% credible level for a flat (frequency-independent) GWB, using a prior which is uniform in the log of the strength of the GWB, with 99% of the sensitivity coming from the band 20–76.6 Hz; ΩGW(f)≤3.4×10−9 at 25 Hz for a power-law GWB with a spectral index of 2/3 (consistent with expectations for compact binary coalescences), in the band 20–90.6 Hz; and ΩGW(f)≤3.9×10−10 at 25 Hz for a spectral index of 3, in the band 20–291.6 Hz. These upper limits improve over our previous results by a factor of 6.0 for a flat GWB, 8.8 for a spectral index of 2/3, and 13.1 for a spectral index of 3. We also search for a GWB arising from scalar and vector modes, which are predicted by alternative theories of gravity; we do not find evidence of these, and place upper limits on the strength of GWBs with these polarizations. We demonstrate that there is no evidence of correlated noise of magnetic origin by performing a Bayesian analysis that allows for the presence of both a GWB and an effective magnetic background arising from geophysical Schumann resonances. We compare our upper limits to a fiducial model for the GWB from the merger of compact binaries, updating the model to use the most recent data-driven population inference from the systems detected during O3a. Finally, we combine our results with observations of individual mergers and show that, at design sensitivity, this joint approach may yield stronger constraints on the merger rate of binary black holes at z≳2

关键词： Gravitational wave detection

来源：评论

学校读者我要写书评

暂无评论

All-sky search for continuous gravitational waves from isolated neutron stars in the early O3 LIGO data

引用

Physical Review D 2021年第8期104卷 082004-082004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 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 report on an all-sky search for continuous gravitational waves in the frequency band 20–2000 Hz and with a frequency time derivative in the range of [−1.0,+0.1]×10−8 Hz/s. Such a signal could be produced by a nearby, spinning and slightly nonaxisymmetric isolated neutron star in our Galaxy. This search uses the LIGO data from the first six months of Advanced LIGO’s and Advanced Virgo’s third observational run, O3. No periodic gravitational wave signals are observed, and 95% confidence-level (C.L.) frequentist upper limits are placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude h0 are ∼1.7×10−25 near 200 Hz. For a circularly polarized source (most favorable orientation), the lowest upper limits are ∼6.3×10−26. These strict frequentist upper limits refer to all sky locations and the entire range of frequency derivative values. For a population-averaged ensemble of sky locations and stellar orientations, the lowest 95% C.L. upper limits on the strain amplitude are ∼1.4×10−25. These upper limits improve upon our previously published all-sky results, with the greatest improvement (factor of ∼2) seen at higher frequencies, in part because quantum squeezing has dramatically improved the detector noise level relative to the second observational run, O2. These limits are the most constraining to date over most of the parameter space searched.

关键词： Astrophysical studies of gravity Gravitational wave detection Gravitational wave sources Gravitational waves

来源：评论

学校读者我要写书评

暂无评论

Research on networking communication technology based on small spacecraft 67

Research on networking communication technology based on sma...

引用

67th International Astronautical Congress, IAC 2016

作者： Peng, Qin Yang, Cao Lu, Gao Zhiye, Jiang Jinliang, Bai National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics China Academy of Launch Vehicle Technology No. 1 Nan Da Hong Men Road Beijing China

Small spacecrafts have many advantages such as distribution area controllable, flexible, easy networking and co-optimal allocation of resources. The distributed collaborative networking technology can make several small spacecrafts to co-ordinate and work together as a whole. The technology has good prospects in the aerospace field and has obtained wide attention, for it can achieve communication transmission, space exploration, decision-making tasks and other functions. This paper proposes a collaborative networking solution based on small spacecraft, focusing on the research of key technologies such as networking method, communication protocols, synchronous communication and interference. This paper designed a collaborative network communication system solution, developed a prototype and verified the feasibility of the solution through simulation analysis and prototype testing. This paper also suggested the ideas and methods to improve future collaborative network communication system. Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Spacecraft

来源：评论

学校读者我要写书评

暂无评论

Derivation of the thermal characteristics of mesoscale eddies

引用

Acta Oceanologica Sinica 2017年第3期36卷 8-13页

作者： CHEN Xuan PAN Jing ZHENG Chongwei ZHANG Xi HE Ming The 75839 Army People's Liberation Army Guangzhou 510510 China National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Dalian Naval Academy People's Liberation Army Dalian 116018 China College of Meteorology and Oceanography People's Liberation Army University of Science and Technology Nanjing 211101 China College of Marine Life Science Ocean University of China Qingdao 266003 China

This study aims at explaining the relationship between thermodynamic characteristics and direction of rotation of mesoscale eddies（MEs）. The geometric characteristics of the MEs are under the following assumptions： the structure of the MEs is symmetrical, and changes of oceanic physical variables are close to linear features in the radial direction in the ME regions. Based on these assumptions, by using primitive equations without friction under a cylindrical coordinate system, the thermodynamic characteristics of the MEs are derived, showing that the conventional relationship of warm anticyclonic eddies with high sea surface height（SSH） and cold cyclonic eddies with low SSH is not consistent with the SSH and sea surface temperature（SST） observations of eddies. The results show that the symmetrical form is an ideal approximation for the geometric characteristics of MEs. In consideration of the above assumptions, there are advantages for derivation of the characteristics of the MEs under a cylindrical coordinate.

关键词： mesoscale eddies thermodynamic characteristics symmetry

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：