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New explicit multi-symplectic scheme for nonlinear wave equation

Applied Mathematics and Mechanics(English Edition) 2014年第3期35卷 369-380页

作者：李昊辰孙建强秦孟兆 Department of Mathematics College of Information Science and TechnologyHainan University State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and System SciencesChinese Academy of Sciences

Based on splitting multi-symplectic structures, a new multi-symplectic scheme is proposed and applied to a nonlinear wave equation. The explicit multi-symplectic scheme of the nonlinear wave equation is obtained, and the corresponding multi-symplectic conservation property is proved. The backward error analysis shows that the explicit multi-symplectic scheme has good accuracy. The sine-Gordon equation and the Klein-Gordon equation are simulated by an explicit multi-symplectic scheme. The numerical results show that the new explicit multi-symplectic scheme can well simulate the solitary wave behaviors of the nonlinear wave equation and approximately preserve the relative energy error of the equation.

关键词： nonlinear wave equation multi-symplectic method backward error analysis

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Comparison of Pulsar Positions from Timing and Very Long Baseline Astrometry

arXiv

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arXiv 2017年

作者： Wang, J.B. Coles, W.A. Hobbs, G. Shannon, R.M. Manchester, R.N. Kerr, M. Yuan, J.P. Wang, N. Bailes, M. Bhat, N.D.R. Dai, S. Dempsey, J. Keith, M.J. Lasky, P.D. Levin, Y. Lowski, S. Os Ravi, V. Reardon, D.J. Rosado, P.A. Russell, C.J. Spiewak, R. van Straten, W. Toomey, L. Wen, L. You, X.-P. Zhu, X.-J. Xinjiang Astronomical Observatory Chinese Academy of Science 150 Science 1-Street Urumqi Xinjiang830011 China Key Laboratory of Radio Astronomy Chinese Academy of Science 150 Science 1-Street Urumqi Xinjiang830011 China CSIRO Astronomy & Space Science PO Box 76 EppingNSW1710 Australia Electrical and Computer Engineering University of California at San Diego La JollaCA United States International Centre for Radio Astronomy Research Curtin University BentleyWA6102 Australia Naval Research Laboratory 4555 Overlook Ave. SW WashingtonDC20375 United States Centre for Astrophysics and Supercomputing Swinburne University of Technology P.O. Box 218 HawthornVIC3122 Australia CSIRO Information Management & Technology Box 225 DicksonACT2602 Jodrell Bank Centre for Astrophysics University of Manchester M13 9PL United Kingdom Monash Centre for Astrophysics School of Physics and Astronomy Monash University VIC3800 Australia Cahill Center for Astronomy and Astrophysics California Institute of Technology MC 249-17 PasadenaCA91125 United States CSIRO Scientific Computing Services Australian Technology Park Locked Bag 9013 AlexandriaNSW1435 Australia School of Physics University of Western Australia CrawleyWA6009 Australia School of Physical Science and Technology Southwest University Chongqing400715 China

Pulsar positions can be measured with high precision using both pulsar timing methods and very-long-baseline interferometry (VLBI). Pulsar timing positions are referenced to a solar-system ephemeris, whereas VLBI positions are referenced to distant quasars. Here we compare pulsar positions from published VLBI measurements with those obtained from pulsar timing data from the Nanshan and Parkes radio telescopes in order to relate the two reference frames. We find that the timing positions differ significantly from the VLBI positions (and also differ between different ephemerides). A statistically significant change in the obliquity of the ecliptic of 2.16 ± 0.33 mas is found for the JPL ephemeris DE405, but no significant rotation is found in subsequent JPL ephemerides. The accuracy with which we can relate the two frames is limited by the current uncertainties in the VLBI reference source positions and in matching the pulsars to their reference source. Not only do the timing positions depend on the ephemeris used in computing them, but also different segments of the timing data lead to varying position estimates. These variations are mostly common to all ephemerides, but slight changes are seen at the 10µas level between ephemerides. Copyright © 2017, The Authors. All rights reserved.

关键词： Pulsars

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Analysis of Sparse Quasi-Newton Updates with Positive Definite Matrix Completion

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Journal of the Operations Research Society of China 2014年第1期2卷 39-56页

作者： Yu-Hong Dai Nobuo Yamashita State Key Laboratory of Scientific and Engineering Computing Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesP.O.Box 2719Beijing 100080People’s Republic of China Department of Applied Mathematics and Physics Graduate School of InformaticsKyoto UniversityKyoto 606-8501Japan

Based on the idea of maximum determinant positive definite matrix completion,Yamashita(Math Prog 115(1):1–30,2008)proposed a new sparse quasi-Newton update,called MCQN,for unconstrained optimization problems with sparse Hessian *** exchange of the relaxation of the secant equation,the MCQN update avoids solving difficult subproblems and overcomes the ill-conditioning of approximate Hessian ***,local and superlinear convergence results were only established for the MCQN update with the DFP *** this paper,we extend the convergence result to the MCQN update with the whole Broyden’s convex *** results are also reported,which suggest some efficient ways of choosing the parameter in the MCQN update the Broyden’s family.

关键词： Quasi-Newton method Large-scale problems Sparsity Positive definite matrix completion Superlinear convergence

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Wireless information and energy transfer for decode-and-forward relying mimo-ofdm networks

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ICIC Express Letters 2015年第7期9卷 1925-1932页

作者： Du, Guanyao Dong, Zhilong Xiong, Ke Qiu, Zhengding School of Computer and Information Technology Beijing Jiaotong University No. 3 Shangyuancun Haidian Dist Beijing China State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences No. 55 Zhongguancun East Road Haidian Dist Beijing China

This paper investigates the system achievable rate and optimization for the multiple-input multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) system with an energy harvesting (EH) relay. Firstly we propose a time switchingbased relaying (TSR) protocol to enable the simultaneous information processing and energy harvesting at the relay. Then, we discuss its achievable rate performance theoretically and formulated an optimization problem to maximize the system achievable rate. As the problem is difficult to solve, we design an Augmented Lagrangian Penalty Function (ALPF) method for it. Extensive simulation results are provided to demonstrate the accuracy of the analytical results and the effectiveness of the ALPF method. © 2015, ISSN 1881-803X.

关键词： Energy harvesting

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A Parallel Computational Model for Three-Dimensional,Thermo-Mechanical Stokes Flow Simulations of Glaciers and Ice Sheets

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Communications in Computational Physics 2014年第9期16卷 1056-1080页

作者： Wei Leng Lili Ju Max Gunzburger Stephen Price State Key Laboratory of Scientific and Engineering Computing Chinese Academy of SciencesBeijing 100190China. Department of Mathematics University of South CarolinaColumbiaSC 29208USA. Department of Scientific Computing Florida State UniversityTallahasseeFL 32306USA. Theoretical Division Los Alamos National LaboratoryLos AlamosNM 87545.USA.

This paper focuses on the development of an efficient,three-dimensional,thermo-mechanical,nonlinear-Stokes flow computational model for ice sheet *** model is based on the parallel finite element model developed in[14]which features high-order accurate finite element discretizations on variable resolution ***,we add an improved iterative solution method for treating the nonlinearity of the Stokes problem,a new high-order accurate finite element solver for the temperature equation,and a new conservative finite volume solver for handling mass *** result is an accurate and efficient numerical model for thermo-mechanical glacier and ice-sheet *** demonstrate the improved efficiency of the Stokes solver using the ISMIP-HOM Benchmark experiments and a realistic test case for the Greenland *** also apply our model to the EISMINT-II benchmark experiments and demonstrate stable thermo-mechanical ice sheet evolution on both structured and unstructured ***,we find no evidence for the“cold spoke”instabilities observed for these same experiments when using finite difference,shallow-ice approximation models on structured grids.

关键词： Stokes-flow modeling ice-sheet modeling finite element approximation finite volume approximation parallel implementation.

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On the stability of the three classes of Newtonian three-body planar periodic orbits

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Science China(Physics,Mechanics & Astronomy) 2014年第11期57卷 2121-2126页

作者： LI XiaoMing LIAO ShiJun School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University Ministry-of-Education Key Laboratory in Scientific Computing Nonlinear Analysis and Applied Mathematics Research Group (NAAM) King Abdulaziz University (KAU)JeddahSaudi Arabia

Currently,the fifteen new periodic orbits of Newtonian three-body problem with equal mass were found by Suvakov and Dmitra sinovi[Phys Rev Lett,2013,110:114301]using the gradient descent method with double *** this paper,these reported orbits are checked stringently by means of a reliable numerical approach(namely the"Clean Numerical Simulation",CNS),which is based on the arbitrary-order Taylor series method and data in arbitrary-digit precision with a procedure of solution *** is found that seven among these fifteen orbits greatly depart from the periodic ones within a long enough interval of time,and are thus most possibly unstable at *** is suggested to carefully check whether or not these seven unstable orbits are the so-called"computational periodicity"mentioned by Lorenz in *** work also illustrates the validity and great potential of the CNS for chaotic dynamic systems.

关键词： unstable Newtonian verification chaotic digit carefully periodicity Clean enough arbitrary

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Automatic image annotation based on co-training

Automatic image annotation based on co-training

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作者： Ke, Xiao Chen, Guolong College of Mathematics and Computer Science Fuzhou University Fuzhou 350108 China Fujian Key Laboratory of Scientific and Engineering Computing Fuzhou 350108 China

Automatic image annotation is a critical and challenging problem in pattern recognition and image understanding areas. There are some problems in existing automatic image annotation areas. For example, the size of unlabeled data is much larger than the labeled data. Besides, most image annotation models can only use one kind of image segmentation strategy and certain image description method. According to the above problems, an automatic image annotation model based on Co-training is proposed. In this model, four independent feature properties are constructed and then four corresponding sub-classifers are built. In this way, different image segmentation strategies and feature representation methods can be integrated into a unified framework. An adaptive algorithm based on vote and consistency is proposed to extend the training dataset. The proposed method use Co-training algorithm and mass unlabeled data to improve the performance of automatic image annotation. Experiments conducted on Corel 5 K dataset verify the effectiveness of proposed method.

关键词： Image annotation

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Toward a multi-tenant college sustained team seeking system

Toward a multi-tenant college sustained team seeking system

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World Congress on Information and Communication Technologies (WICT)

作者： Shuwei Yao Kun Ma Zhe Yang Ajith Abraham School of Information Science and Engineering University of Jinan Jinan China Shandong Provincial Key Laboratory of Network Based Intelligent Computing University of Jinan Jinan China Shandong Provincial Key Laboratory of Software Engineering Shandong University Jinan China IT4Innovations - Center of excellence VSB - Technical University of Ostrava Czech Republic Machine Intelligence Research Labs Scientific Network for Innovation and Research Excellence Auburn USA

College students often collaborate in some projects or contests with other students from different majors, but current team seeking system has some limitations on finding teammates. In this paper, we design a multi-tenant college sustained team seeking system, aiming at establishing a sustained team among college students who have similar interest. We present the architecture, core modules, and some emerging techniques to design such a system. The evaluation of query efficiency and page loading speed are present at last.

关键词： Databases Cache storage Loading Servers Rendering (computer graphics) Information and communication technology

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Laser interferometric gravitational wave detection in space and structure formation in the early universe

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Chinese Astronomy and Astrophysics 2015年第4期39卷 411-446页

作者： Gong, Xue-Fei Xu, Sheng-Nian Yuan, Ye-Fei Bai, Shan Bian, Xing Cao, Zhou-Jian Chen, Ge-Rui Dong, Peng Gao, Tian-Shu Gao, Wei Huang, Shuang-Lin Luo, Zi-Ren Shao, Ming-Xue Sun, Bao-San Tang, Wen-Lin Yu, Pin Xu, Peng Zang, Yun-Long Zhang, Hai-Peng Lau, Yun-Kau Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China University of Science and Technology of China Department of Astronomy Hefei 230026 China Theoretisch-Physikalisches Institut Friedrich-Schiller-Universität Jena Jena D-07743 Germany University of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China Beijing University of Technology College of Applied Sciences Beijing 100124 China Morningside Center of Mathematics Chinese Academy of Sciences Beijing 100190 China Capital Normal University Beijing 100089 China Henan University Department of Mathematics Kaifeng 475001 China Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China Henan Polytechnic University Jiaozuo Henan 454000 China Huazhong University of Science and Technology School of Physics Wuhan 430074 China Tshinghua University Mathematical Sciences Center Beijing 100083 China Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China

The laser interferometric gravitational wave detection in space is an important and realistic approach to studying some key problems of astronomy and cosmology, such as the stellar evolution and galactic formation in the early universe, the co-evolution of black holes and galaxies, etc. After performing two stages of the Advance Research Project of Space Science commissioned by the Chinese Academy of Sciences, and by weighing the feasibility of technology and the foresight of science, we have selected the gravitational wave sources including the high-redshift intermediate-and-large mass binary black hole mergers, and the intermediate-mass black holes in clusters and other dense dynamic environments, as the main scientific objectives, and given a preliminary design for the project of Chinese space gravitational wave detection in the frequency range from millihertz to hertz. Based on this, here we introduce briefly the science of the space gravitational wave detection, as a new measure of astronomical observations, as well as the scientific objectives and potential detectivity of the design for the Chinese space gravitational wave detection mission.

关键词： Binary black hole coalescence Gravitational wave intermediate mass black hole ΛCDM hierarchical structure formation picture

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Strong and stable geographic differentiation of swamp buffalo maternal and paternal lineages indicates domestication in the China/Indochina border region

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Molecular Ecology 2016年第7期25卷 1530-1550页

作者： Zhang, Yi Lu, Yongfang Yindee, Marnoch Li, Kuan-Yi Kuo, Hsiao-Yun Ju, Yu-Ten Ye, Shaohui Faruque, Md Omar Li, Qiang Wang, Yachun Cuong, Vu Chi Pham, Lan Doan Bouahom, Bounthong Yang, Bingzhuang Liang, Xianwei Cai, Zhihua Vankan, Dianne Manatchaiworakul, Wallaya Kowlim, Nonglid Duangchantrasiri, Somphot Wajjwalku, Worawidh Colenbrander, Ben Zhang, Yuan Beerli, Peter Lenstra, Johannes A. Barker, J. Stuart F. National Engineering Laboratory for Animal Breeding Key Laboratory of Animal Genetics and Breeding and Reproduction of MOA College of Animal Science and Technology China Agricultural University Beijing 100193 China Department of Clinical Science and Public Health Faculty of Veterinary Science Mahidol University Kanchanaburi Campus Kanchanaburi 71150 Thailand Department of Animal Science and Technology National Taiwan University Taipei 10673 Taiwan Livestock Research Institute Council of Agriculture Tainan 71246 Taiwan College of Animal Science and Technology Yunnan Agricultural University Kunming 650201 China Department of Animal Breeding and Genetics Bangladesh Agricultural University Mymensingh 2202 Bangladesh Key Laboratory of Animal Cell Technology National Institute of Animal Sciences Tu Liem Hanoi 100000 Viet Nam National Agriculture and Forestry Research Institute P.O. Box 811 Vientiane Capital Laos Guangxi Buffalo Research Institute Chinese Academy of Agriculture Sciences Nanning 530001 China College of Animal Science Anhui Science and Technology University Fengyang 233100 China School of Veterinary Science University of Queensland Gatton Campus Gatton 4343 Qld Australia Department of Pathology Faculty of Veterinary Medicine Kasetsart University Kamphaengsaen Nakhon Pathom 73140 Thailand Khao-Nang-Ram Wildlife Research Station Department of National Parks Wildlife and Plant Conservation Bangkok 10900 Thailand Faculty of Veterinary Medicine Utrecht University Yalelaan 104 Utrecht 3584 CM Netherlands Department of Scientific Computing Florida State University Tallahassee 32306-4120 FL United States School of Environmental and Rural Science University of New England Armidale 2351 NSW Australia

The swamp type of the Asian water buffalo is assumed to have been domesticated by about 4000 years BP, following the introduction of rice cultivation. Previous localizations of the domestication site were based on mitochondrial DNA (mtDNA) variation within China, accounting only for the maternal lineage. We carried out a comprehensive sampling of China, Taiwan, Vietnam, Laos, Thailand, Nepal and Bangladesh and sequenced the mtDNA Cytochrome b gene and control region and the Y-chromosomal ZFY, SRY and DBY sequences. Swamp buffalo has a higher diversity of both maternal and paternal lineages than river buffalo, with also a remarkable contrast between a weak phylogeographic structure of river buffalo and a strong geographic differentiation of swamp buffalo. The highest diversity of the swamp buffalo maternal lineages was found in south China and north Indochina on both banks of the Mekong River, while the highest diversity in paternal lineages was in the China/Indochina border region. We propose that domestication in this region was later followed by introgressive capture of wild cows west of the Mekong. Migration to the north followed the Yangtze valley as well as a more eastern route, but also involved translocations of both cows and bulls over large distances with a minor influence of river buffaloes in recent decades. Bayesian analyses of various migration models also supported domestication in the China/Indochina border region. Coalescence analysis yielded consistent estimates for the expansion of the major swamp buffalo haplogroups with a credibility interval of 900 to 3900 years BP. The spatial differentiation of mtDNA and Y-chromosomal haplotype distributions indicates a lack of gene flow between established populations that is unprecedented in livestock. © 2015 John Wiley & Sons Ltd.

关键词： Bubalus bubalis migration models mitochondrial DNA Y-chromosomal sequences

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