检索结果-内蒙古大学图书馆

Systematic centroid error compensation for the simple Gaussian PSF in an electronic star map simulator

Chinese Journal of Aeronautics 2014年第4期27卷 884-891页

作者： Wang Haiyong Wang Yonghai Li Zhifeng Song Zhenfei School of Astronautics Beihang University Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics

Simulated star maps serve as convenient inputs for the test of a star sensor, whose standardability mostly depends on the centroid precision of the simulated star image, so it is necessary to accomplish systematic error compensation for the simple Gaussian PSF（or SPSF, in which PSF denotes point spread function）. Firstly, the error mechanism of the SPSF is described, the reason of centroid deviations of the simulated star images based on SPSF lies in the unreasonable sampling positions（the centers of the covered pixels） of the Gaussian probability density function. Then in reference to the IPSF simulated star image spots regarded as ideal ones, and by means of normalization and numerical fitting, the pixel center offset function expressions are got, so the systematic centroid error compensation can be executed simply by substituting the pixel central position with the offset position in the SPSF. Finally, the centroid precision tests are conducted for the three big error cases of Gaussian radius r = 0.5, 0.6, 0.671 pixel, and the centroid accuracy with the compensated SPSF（when r = 0.5） is improved to 2.83 times that of the primitive SPSF, reaching a 0.008 pixel error, an equivalent level of the IPSF. Besides its simplicity, the compensated SPSF further increases both the shape similarity and the centroid precision of simulated star images, which helps to improve the image quality and the standardability of the outputs of an electronic star map simulator（ESS）.

关键词： Error compensation Image analysis Point spread function Star map simulation Star sensor

来源：评论

学校读者我要写书评

暂无评论

Comparison between Two HLL-type riemann solvers for strong shock calculation on ALE framework

Comparison between Two HLL-type riemann solvers for strong s...

引用

International MultiConference of Engineers and Computer Scientists 2015, IMECS 2015

作者： Shen, Zhijun Yan, Wei National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing100088 China

ISBN: (纸本)9789881925329

This paper investigates solution behaviors under the strong shock interaction for moving mesh schemes based on the one-dimensional HLL-type Riemann solvers. numerical experiments show that some schemes which updates the flow parameters directly on the moving mesh without using interpolation, may suffer from severe instability such as grid distortion. But the HLL solver can be free from such failings. It is well known that the numerical schemes on a fixed grid that can capture contact discontinuity accurately usually suffer from some disastrous carbuncle phenomenon, while others, such as the HLL scheme, are free from this kind of shock instability. Due to such high similarity, a research to combine the grid deformation and the numerical shock instability is developed. Furthermore, in order to unveil the cause of producing these failings, a HLL-type solver (denoted as the HLLS) with shear wave is constructed for inviscid, compressible gas flows and implemented into the arbitrary Lagrangian Eulerian (ALE) method. With the vorticity viscosity vanishing, the ALE HLLS scheme produce some numerical instability phenomena. This result indicates that viscosity associated to the shear wave may be unique reason to cause the instability or nonphysical deformation.

关键词： Shear waves

来源：评论

学校读者我要写书评

暂无评论

numerical analysis for some parallel algorithms with large step length spatial discretizations for 2-dimensional heat equation

Numerical analysis for some parallel algorithms with large s...

引用

International MultiConference of Engineers and Computer Scientists 2015, IMECS 2015

作者： Cui, Xia Sheng, Zhi-Qiang National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing100088 China

ISBN: (纸本)9789881925329

Some simple and efficient domain decomposition algorithms for 2-dimensional heat equation are studied. The values at the interface points are calculated by using implicit schemes derived by discretizing the spatial partial derivatives in two directions with large step lengths alternatively. On sub-domain calculation, three algorithms including traditional fully implicit scheme, Crank-Nicolson scheme and explicit-implicit scheme are considered. By using a constructive reasoning procedure with the help of discrete maximum principle, the stability and accuracy properties of the new algorithms are analyzed. Theoretical analysis and numerical experiments show that by applying these algorithms, the calculation work is simplified, and the stability and convergence conditions are loosen to a quite great extent. The algorithms have perfect accuracy and high parallel efficiency and scalability.

关键词： numerical analysis

来源：评论

学校读者我要写书评

暂无评论

Monotone finite volume schemes for diffusion equations on distorted quadrilateral meshes

Monotone finite volume schemes for diffusion equations on di...

引用

International MultiConference of Engineers and Computer Scientists 2015, IMECS 2015

作者： Yue, Jing-Yan Yuan, Guang-Wei Sheng, Zhi-Qiang National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing100088 China

ISBN: (纸本)9789881925329

We construct a new monotone finite volume scheme for diffusion problem on distorted quadrilateral meshes, and the scheme also takes account of the geometric distortion of cells and changes of physical variables on each edge, moreover, a part of the mesh stencil is fixed. The new scheme is proved to be monotone, i.e. it preserves positivity of analytical solutions. numerical results are presented to demonstrate the numerical performance of our new monotone scheme such as solution positivity-preserving, conservation, accuracy and efficiency on distorted meshes.

关键词： Partial differential equations

来源：评论

学校读者我要写书评

暂无评论

94 β-Decay Half-Lives of Neutron-Rich Cs55 to Ho67: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation

引用

Physical Review Letters 2017年第7期118卷 072701-072701页

作者： J. Wu S. Nishimura G. Lorusso P. Möller E. Ideguchi P.-H. Regan G. S. Simpson P.-A. Söderström P. M. Walker H. Watanabe Z. Y. Xu H. Baba F. Browne R. Daido P. Doornenbal Y. F. Fang N. Fukuda G. Gey T. Isobe Z. Korkulu P. S. Lee J. J. Liu Z. Li Z. Patel V. Phong S. Rice H. Sakurai L. Sinclair T. Sumikama M. Tanaka A. Yagi Y. L. Ye R. Yokoyama G. X. Zhang D. S. Ahn T. Alharbi N. Aoi F. L. Bello Garrote G. Benzoni A. M. Bruce R. J. Carroll K. Y. Chae Z. Dombradi A. Estrade A. Gottardo C. J. Griffin N. Inabe D. Kameda H. Kanaoka I. Kojouharov F. G. Kondev T. Kubo S. Kubono N. Kurz I. Kuti S. Lalkovski G. J. Lane E. J. Lee T. Lokotko G. Lotay C.-B. Moon D. Murai H. Nishibata I. Nishizuka C. R. Nita A. Odahara Zs. Podolyák O. J. Roberts H. Schaffner C. Shand Y. Shimizu H. Suzuki H. Takeda J. Taprogge S. Terashima Z. Vajta S. Yoshida School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China RIKEN Nishina Center 2-1 Hirosawa Wako-shi Saitama 351-0198 Japan National Physical Laboratory NPL Teddington Middlesex TW11 0LW United Kingdom Department of Physics University of Surrey Guildford GU2 7XH United Kingdom Theoretical Division Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Research Center for Nuclear Physics (RCNP) Osaka University Ibaraki Osaka 567-0047 Japan LPSC Universite Joseph Fourier Grenoble 1 CNRS/IN2P3 Institut National Polytechnique de Grenoble F-38026 Grenoble Cedex France School of Engineering University of the West of Scotland Paisley PA1 2BE United Kingdom Scottish Universities Physics Alliance University of Glasgow Glasgow G12 8QQ United Kingdom IRCNPC School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China Department of Physics the University of Hong Kong Pokfulam Road Hong Kong Department of Physics University of Tokyo Hongo 7-3-1 Bunkyo-ku 113-0033 Tokyo Japan School of Computing Engineering and Mathematics University of Brighton Brighton BN2 4GJ United Kingdom Department of Physics Osaka University Machikaneyama-machi 1-1 Osaka 560-0043 Toyonaka Japan Institut Laue-Langevin B.P. 156 F-38042 Grenoble Cedex 9 France Institute for Nuclear Research Hungarian Academy of Sciences P. O. Box 51 Debrecen H-4001 Hungary Department of Physics Chung-Ang University Seoul 156-756 Republic of Korea Faculty of Physics VNU Hanoi University of Science 334 Nguyen Trai Thanh Xuan Hanoi Vietnam Department of Physics University of York Heslington York YO10 5DD United Kingdom Center for Nuclear Study (CNS) University of Tokyo Wako-shi Saitama 351-0198 Japan Department of Physics College of Science in Zulfi Almajmaah University P.O. Box 1712 11932 Saudi Arabia University of Oslo P.O. Box 1072 Blindern 0316 Oslo Norway INFN Sezione di Milano via Celoria

The β-decay half-lives of 94 neutron-rich nuclei Cs144−151, Ba146−154, La148−156, Ce150−158, Pr153−160, Nd156−162, Pm159−163, Sm160−166, Eu161−168, Gd165−170, Tb166−172, Dy169−173, Ho172−175, and two isomeric states Er174m, Dy172m were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β-decay half-lives are observed at neutron-number N=97 for Ce58, Pr59, Nd60, and Sm62, and N=105 for Eu63, Gd64, Tb65, and Dy66. Features in the data mirror the interplay between pairing effects and microscopic structure. r-process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.

关键词： Beta decay Nuclear reactions r process 150 ≤ A ≤ 189 Collective models Nuclear structure & decays Radioactive beams Spectrometers & spectroscopic techniques

来源：评论

学校读者我要写书评

暂无评论

Decadal Variability of Global Ocean Significant Wave Height

引用

Journal of Ocean University of China 2015年第5期14卷 778-782页

作者： ZHENG Chongwei ZHOU Lin SHI Weilai LI Xin HUANG Chaofan College of Meteorology and Oceanography People’s Liberation Army University of Science&Technology National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics the Chinese Academy of Sciences Dalian Naval Academy Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology

This paper presents the long-term climate changes of significant wave height(Hs) in 1958–2001 over the entire global ocean using the 45-year European Centre for Medium-Range Weather Forecasts(ECMWF) Reanalysis(ERA-40) wave data. The linear trends in Hs and regional and seasonal differences of the linear trends for Hs were calculated. Results show that the Hs exhibits a significant increasing trend of about 4.6 cm decade-1 in the global ocean as a whole over the last 44 years. The Hs changes slowly during the periods 1958–1974 and 1980–1991, while it increases consistently during the periods 1975–1980 and 1995–1998. The Hs reaches its lowest magnitude in 1975, with annual average wave height about 2 m. In 1992, the Hs has the maximum value of nearly 2.60 m. The Hs in most ocean waters has a significant increasing trend of 2–14 cm decade-1 over the last 44 years. The linear trend exhibits great regional differences. Areas with strong increasing trend of Hs are mainly distributed in the westerlies of the southern Hemisphere and the northern Hemisphere. Only some small areas show obvious decreasing in Hs. The long-term trend of Hs in DJF(December, January, February) and MAM(March, April, May) is much more stronger than that in JJA(June, July, August) and SON(September, October, November). The linear trends of the Hs in different areas are different in different seasons; for instance, the increasing trend of Hs in the westerlies of the Pacific Ocean mainly appears in MAM and DJF.

关键词： global ocean significant wave height long-term trend regional differences seasonal differences dominant season

来源：评论

学校读者我要写书评

暂无评论

Gravitational wave astronomy: the current status

引用

science China(physics,Mechanics & Astronomy) 2015年第12期58卷 3-43页

作者： BLAIR David JU Li ZHAO ChunNong WEN LinQing CHU Qi FANG Qi CAI RongGen GAO JiangRui LIN XueChun LIU Dong WU Ling-An ZHU ZongHong REITZE David H. ARAI Koji ZHANG Fan FLAMINIO Raffaele ZHU XingJiang HOBBS George MANCHESTER Richard N. SHANNON Ryan M. BACCIGALUPI Carlo GAO Wei XU Peng BIAN Xing CAO ZhouJian CHANG ZiJing DONG Peng GONG XueFei HUANG ShuangLin JU Peng LUO ZiRen QIANG Li'E TANG WenLin WAN XiaoYun WANG Yue XU ShengNian ZANG YunLong ZHANG HaiPeng LAU Yun-Kau NI Wei-Tou School of Physics The University of Western Australia State Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences The School of Physics & Electronic Engineering Shanxi University Laboratory of All-Solid-State Light Sources Institute of Semiconductors Chinese Academy of Science State Key Laboratroy of Modern Optical Instrumentation Department of Optical Engineering Zhejiang University Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Gravitational Wave and Cosmology Laboratory Department of Astronomy Beijing Normal University LIGO Laboratory California Institute of Technology Department of Physics University of Florida Department of Physics West Virginia University National Astronomical Observatory of Japan CSIRO Astronomy and Space Science International Centre for Radio Astronomy Research Curtin University SISSA Astrophysics Sector Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences University of Chinese Academy of Sciences Morningside Center of Mathematics Chinese Academy of Sciences State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of Sciences Department of Mathematics Henan University Department of Mathematics Capital Normal University Department of Geophysics College of the Geology Engineering and Geomatics Chang'an University QUEST Centre of Quantum Engineering and Space-Time Research Leibniz Universitt Hannover Max-Planck-Institut für Gravitationsphysik(Albert Einstein Institut) Aerospace Flight Dynamics Laboratory Beijing Aerospace Control Center Qian Xuesen Laboratory of Launch Vehicle Technology Center for Gravitation and Cosmology Department of Physics Tsing Hua University

In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan,which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1–5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.

关键词： gravitational waves ground based detectors pulsar timing spaced based detectors CMB

来源：评论

学校读者我要写书评

暂无评论

X-band narrowband high-temperature super-conducting filter with high selectivity

X-band narrowband high-temperature super-conducting filter w...

引用

IET International Radar Conference 2015

作者： L. Gao Z. Y. Jiang J. Q. Liu H. Y. Liu J. L. Bai F. Xu H. Li S. Y. Chen L. Sun Y. B. Bian J. Wang Y. S. He National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics P.O. box 9200 Beijing 100076 China Chinese Academy of Sciences Beijing Beijing CN

ISBN: (纸本)9781510822023

This paper presents a development of a narrowband hightemperature superconducting filter with high selectivity. The center frequency of this filter is 8.625 GHz and the 3 dB bandwidth is 156 MHz (a fractional bandwidth of 1.81 %). In order to achieve high band edge steepness, we introduce a 10-resonator quasi-elliptic function response with two pairs of transmission zeros in the cascaded quadruplet coupling structure. The filter was manufactured on a 2-in-diameter 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a midband insertion loss of 0.58 dB and a return loss better than 16 dB. Band edge steepness reaches over 3.82 dB/MHz at both the high and low frequency edges. The 60 dB rectangle ratio is less than 1.19. The out-of-band rejection is over 60 dB at 17.8 MHz from the 3 dB band edge.

关键词： High-temperature superconducting (HTS) X-band microwave filter transmission zeros

来源：评论

学校读者我要写书评

暂无评论

Performance test of Fourier transform infrared imaging spectrometer

引用

Guangxue Jingmi Gongcheng/Optics and Precision Engineering 2015年 23卷 190-196页

作者： Li, Jian-Hua Xue, Feng Xue, Lian Li, Zhi-Feng Liu, Jia-Qi National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Beijing100076 China

The paper researches the measurement methods of key parameters of Fourier transform imaging spectrometers. Firstly, the physical meaning of the key parameter Noise Equivalent Spectral Radiance (NESR) was introduced and corresponding calculation model, test principle and data processing method were given. Then, a calibrated black body was used as radiation source, the performance parameters of Fourier transform imaging spectrometer for mid-wavelength and long-wavelength were tested experimentally, including the NESR, radiometric accuracy and spectral errors. test results show that the average NESRs of infrared imaging spectrometer for long-wavelength at 10 μm is 21.4 nW/(cm2·sr·cm-1) and that for mid-wavelength at 4.6 μm is 4.6 nW/(cm2·sr·cm-1). The radiometric accuracies of the spectrometer is less than 0.4 K and 2 K for long-wave and mid-wave, respectively. The spectral errors of the spectrometer for both mid-wavelength and long-wavelength are less than half of the spectral resolution. These parameters are all in the normal range, which verifies the feasibility of test method. It provides references for the periodically measurement of imaging spectrometers. © 2015, Chinese Academy of sciences. All right reserved.

关键词： Temperature measurement

来源：评论

学校读者我要写书评

暂无评论

A novel GCV-based criterion for parametric PSF estimation 12

A novel GCV-based criterion for parametric PSF estimation

引用

2014 12th IEEE International Conference on Signal Processing, ICSP 2014

作者： Xue, Feng Liu, Jiaqi Li, Zhifeng Meng, Gang National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781479921881

We propose a generalized cross validation (GCV) as a novel criterion for estimating a point spread function (PSF) from the degraded image only. The PSF is obtained by minimizing this new objective functional over a family of Wiener processings. Based on this estimated PSF, we then perform deconvolution using our recently developed SURE-LET algorithm. The GCV-based criterion is exemplified with a number of parametric PSF, involving a scaling factor that controls the blur size. A typical example of such parametrization is the Gaussian kernel. The experimental results demonstrate that the GCV minimization yields highly accurate estimates of the PSF parameters, which also result in a negligible loss of visual quality, compared to that obtained with the exact PSF. The highly competitive results outline the great potential of developing more powerful blind deconvolution algorithms based on this criterion. © 2014 IEEE.

关键词： Optical transfer function

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：