检索结果-南通市图书馆

大地测量与地球动力学 2024年

作者：刘甜甜沈强 shum c k 江利明汪汉胜高凡张旭中国科学院精密测量科学与技术创新研究院中国科学院大学俄亥俄州立大学地球科学学院大地测量科学部

联合IcESat、cryoSat-2和IcESat-2测高卫星数据，估算全南极冰架2003～2022年厚度产品。结果显示，南极冰架整体为减薄趋势，其中Amundsen区域厚度减薄最快，Amery区域减薄最缓慢。

关键词：南极冰架厚度 IcESat cryosat-2 IcESat-2

南极和格陵兰岛GPS连续台站背景噪声时空特性

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

地球物理学报 2024年第1期67卷 63-76页

作者：潘元进张小红吴奇文焦佳爽丁浩沈嗣钧武汉大学测绘学院武汉430079 湖北珞珈实验室武汉430079 武汉大学中国南极测绘研究中心武汉430079 大地测量与地球动力学国家重点实验室武汉430077

基于GPS观测数据获取的陆地垂向运动对研究现今两极区域的冰川质量变化具有重要的科学意义.受地表环境负荷对GPS时间序列中背景噪声空间异质性的影响,在利用GPS时间序列获取垂向速度场时,估计结果存在较大不确定度.本文针对南极和格陵... 详细信息

基于GPS观测数据获取的陆地垂向运动对研究现今两极区域的冰川质量变化具有重要的科学意义.受地表环境负荷对GPS时间序列中背景噪声空间异质性的影响,在利用GPS时间序列获取垂向速度场时,估计结果存在较大不确定度.本文针对南极和格陵兰岛区域的GPS连续观测时间序列中背景噪声的空间特性对速度场及其不确定度的影响问题,利用地表环境负荷模型(包括大气、非潮汐海洋和水文负荷)和重力卫星GRAcE/GRAcE-FO观测数据反演的地表弹性形变对GPS时间序列进行了改正.通过对改正前后的数据进行背景噪声特性分析,揭示出修正环境负荷形变能够有效降低极区GPS时间序列背景噪声幅度,但是大气和非潮汐海洋负荷改正造成了大多数台站背景噪声谱指数的减小,南极和格陵兰岛分别约为其GPS台站总数的46.1%和84.6%,直接导致了对GPS速度不确定度估计的改善效果不明显.对背景噪声空间异质性的研究结果表明,极区台站的背景噪声参数主要表现为随纬度变化的空间特性.

关键词： GPS GRAcE/GRAcE-FO 环境负荷 GPS背景噪声

维普期刊数据库博看期刊

Effects of Gaussian filter in processing GRAcE data: Gravity rate of change at Lhasa,southern Tibet

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2011年第9期54卷 1378-1385页

作者： SUN Wenke HASEGAWA Takashi ZHANG XinLin FUkUDA Yoichi shum c. k. WANG Lei key Laboratory of computational Geodynamics Graduate University of Chinese Academy of Sciences Beijing 100049 China Department of Geophysics Kyoto University Japan Earthquake Research Institute The University of Tokyo Japan Division of Geodetic Science School of Earth Sciences The Ohio State University OH 43210-1398 USA

In this paper, the spatial gravity distribution over Tibetan Plateau and the gravity rate of change at Lhasa for different Gaussian filter radii are computed using GRAcE data. Results show that the estimate of the gravity rate of change is spatialradius-dependent of the Ganssian filter. The GRAcE-estimated gravity rate of change agrees well with the surface measured one. In other words, the GRAcE-estimated gravity rate of change has a limited value as that obtained by surface measurement when the spatial filter radius reaches zero. Then numerical simulations are made for different spatial radii of the Gaussian filter to investigate its behaviors when applied to surface signals. Results show that the estimate of a physical signal is filter-radius dependent. If the computing area is equal to or less than the mass area, especially for a uniformly distributed mass, the estimate gives an almost correct result, no matter what filter radius is used. The estimate has large error because of the signal leakage caused by harmonic truncation if the computing area is much bigger than the mass distribution （or inverse for a small mass anomaly）. If a mass anomaly is too small, it is difficult to recover it from space observation unless the filter radius is extremely small. If the computing point （or area） is outside the mass distribution, the estimated result is almost zero, particularly for small filter radii. These properties of the Gaussian filter are helpful in applying GRAcE data in different geophysical problems with different spatial position and geometrical size. We further discuss physical sources causing the scalar gravity change at Lhasa. Discussions indicate that the gravity rate of change at Lhasa is not caused by the present-day ice melting （PDIM）（or Little Ice Age, LIA） effect because no ice melting occurs in Lhasa city and nearby. The gravity rate of change is attributable mainly to tectonic deformation associated with the Indian Plate collision. Simultaneous surf

关键词： gravity change GRAcE Gaussian filter Tibetan Plateau Lhasa

基于ITRF97的上海和鹿岛VLBI站地壳垂直形变的VLBI测定

在线全文

学校读者我要写书评

暂无评论

天文学报 2002年第2期43卷 205-211页

作者：杨志根朱文耀 shum c.k 舒逢春中国科学院上海天文台中国科学院国家天文台北京 100012 Ohio State University

利用美国宇航局(NASA)在1999年的VLBI全球解(glb1123)中关于上海VLBI站与国际上13个VLBI站的基线长变化率高精度测定结果,以及日本鹿岛kashima和kashima 34两VLBI站分别与国际VLBI站间的相应结果,基于最近的国际地球参考架ITRF97,估计... 详细信息

利用美国宇航局(NASA)在1999年的VLBI全球解(glb1123)中关于上海VLBI站与国际上13个VLBI站的基线长变化率高精度测定结果,以及日本鹿岛kashima和kashima 34两VLBI站分别与国际VLBI站间的相应结果,基于最近的国际地球参考架ITRF97,估计得到了上海VLBI站和日本鹿岛两VLBI站相对于板块稳定区的地壳垂直形变率分别为-1.91±0.56 mm/yr、-3.72±0.74 mm/yr和-8.81±0.84mm/yr,表明上海VLBI站存在每年近2毫米的下降,讨论并证实日本鹿岛两VLBI站的地壳垂直形变速率是不一致的;基于不同板块运动模型的欧拉旋转矢量,估计得到了上述3站的水平形变速率;还估计给出了太平洋板块中部的形变率结果.

关键词：天体测量学 VLBI基线测量地球参考架甚长基线干涉测量地壳垂直形变上海 VLBI站

Brillouin klein space and half-turn space in three-dimensional acoustic crystals

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2024年第13期69卷 2050-2058页

作者： Zhenxiao Zhu Linyun Yang Jien Wu Yan Meng Xiang Xi Bei Yan Jingming chen Jiuyang Lu Xueqin Huang Weiyin Deng ce Shang Perry Ping shum Yihao Yang Hongsheng chen kexin Xiang Gui-Geng Liu Zhengyou Liu Zhen Gao State key Laboratory of Optical Fiber and cable Manufacture Technology Department of Electronic and Electrical EngineeringSouthern University of Science and TechnologyShenzhen 518055China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China key Laboratory of Artificial Micro-and Nanostructures of Ministry of Education and School of Physics and Technology Wuhan UniversityWuhan 430072China king Abdullah University of Science and Technology(kAUST) Physical Science and Engineering Division(PSE)Thuwal 23955-6900Saudi Arabia Interdisciplinary center for Quantum Information State Key Laboratory of Modern Optical InstrumentationZJU-Hangzhou Global Science and Technology Innovation CenterCollege of Information Science and Electronic EngineeringZJU-UIUC InstituteZhejiang UniversityHangzhou 310027China Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore Institute for Advanced Studies Wuhan UniversityWuhan 430072China

The Bloch band theory and Brillouin zone(BZ)that characterize wave-like behaviors in periodic mediums are two cornerstones of contemporary physics,ranging from condensed matter to topological *** theoretical breakthrough revealed that,under the projective symmetry algebra enforced by artificial gauge fields,the usual two-dimensional(2D)BZ(orientable Brillouin two-torus)can be fundamentally modified to a non-orientable Brillouin klein bottle with radically distinct manifold ***,the physical consequence of artificial gauge fields on the more general three-dimensional(3D)BZ(orientable Brillouin three-torus)was so far ***,we theoretically discovered and experimentally observed that the fundamental domain and topology of the usual 3D BZ can be reduced to a non-orientable Brillouin klein space or an orientable Brillouin half-turn space in a 3D acoustic crystal with artificial gauge *** experimentally identify peculiar 3D momentum-space non-symmorphic screw rotation and glide reflection symmetries in the measured band ***,we experimentally demonstrate a novel stacked weak klein bottle insulator featuring a nonzero Z2 topological invariant and self-collimated topological surface states at two opposite surfaces related by a nonlocal twist,radically distinct from all previous 3D topological *** discovery not only fundamentally modifies the fundamental domain and topology of 3D BZ,but also opens the door towards a wealth of previously overlooked momentum-space multidimensional manifold topologies and novel gaugesymmetry-enriched topological physics and robust acoustic wave manipulations beyond the existing paradigms.

关键词： Momentum-space non-symmorphic symmetry Brillouin klein space and half-turn space Acoustic klein bottle insulator Self-collimated topological surface states

Analytic perturbation solutions to the Venusian orbiter due to the nonspherical gravitational potential

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china Mathematics 2000年第5期43卷 552-560页

作者：刘林 c.k.shum Department of Astronomy Nanjing University Nanjing 210093 China The Texas University at Austin Center for Space Research

The analytic perturbation solutions to the motions of a planetary orbiter given in this paper are effective for 0e1, where e is the orbital eccentricity of the orbiter. In the solution, it is assumed that the rotation of the central body is slow, and its astronomical background is clear. Examples for such planets in the solar system are Venus and Mercury. The perturbation solution is tested numerically on two Venusian orbiters with eccentric orbits, PVO and Magellan, and found to be effective.

关键词： slow rotation central body Venusian orbiter nonspherical gravitational potential analytic per- turbation solutions.

correction of cT Burst Array Errors in the Generalized-Lee-RT Spaces

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2010年第8期26卷 1475-1484页

作者： Sapna JAIN k.P.shum Department of Mathematics University of Delhi Department of Mathematics The University of Hong Kong

In [Jain, S.： Array codes in the generalized-Lee-RT-pseudo-metric （the GLRTP-metric）, to appear in Algebra colloq.], Jain introduced a new pseudo-metric on the space Matm×s（Zq）, the module space of all m × s matrices with entries from the finite ring Zq, generalized the classical Lee metric [Lee, c. Y.： Some properties of non-binary error correcting codes. IEEE Trans. Inform. Theory, IT-4, 77- 82 （1958）] and array RT-metric [Rosenbloom, M. Y., Tsfasman, M. A.： codes for m-metric. Prob. Inf. Transm., 33, 45-52 （1997）] and named this pseudo-metric as the Generalized-Lee-RT-Pseudo-Metric （or the GLRTP-Metric）. In this paper, we obtain some lower bounds for two-dimensional array codes correcting cT burst array errors [Jain, S.： cT bursts from classical to array coding. Discrete Math., 308-309, 1489-1499 （2008）] with weight constraints under the GLRTP-metric.

关键词： Linear array codes Lee metric RT metric cT burst array errors

On p-nilpotency and minimal subgroups of finite groups

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2003年第2期46卷 176-186页

作者：郭秀云 k.P.shum Department of Mathematics Shanxi University Department of Mathematics The Chinese University of Hong Kong

We call a subgroup H of a finite group G c-supplemented in G if there exists a subgroup k ofG such that G = Hk and H ∩k ≤ core(H). In this paper it is proved that a finite group G is p-nilpotentif G is S4-free and every minimal subgroup of P ∩ GN is c-supplemented in NG(P), and when p = 2 P isquaternion-free, where p is the smallest prime number dividing the order of G, P a Sylow p-subgroup of *** some applications of this result, some known results are generalized.

关键词： p-nilpotent groups, minimal subgroups, formation.

A possible interrelation between Earth rotation and climatic variability at decadal time-scale

在线全文

学校读者我要写书评

暂无评论

Geodesy and Geodynamics 2016年第3期7卷 216-222页

作者： Leonid Zotov c.Bizouard c.k.shum National Research University Higher School of Economics Moscow Institute of Electronics and Mathematics Lomonosov Moscow State University Sternberg Astronomical Institute SYRTE Observatoire de Paris PSL Research University CNRS Sorbonne Universités UPMC Univ Division of Geodetic Science School of Earth Sciences The Ohio State University State key Laboratory of Geodesy and Earth's Dynamics Institute of Geodesy & Geophysics Chinese Academy of Sciences

Using multichannel singular spectrum analysis （MSSA） we decomposed climatic time se- ries into principal components, and compared them with Earth rotation parameters. The global warming trends were initially subtracted. Similar quasi 60 and 20 year periodic os- cillations have been found in the global mean Earth temperature anomaly （HadcRUT4） and global mean sea level （GMSL）. Similar cycles were also found in Earth rotation variation. Over the last 160 years multi-decadal change of Earth＇s rotation velocity is correlated with the 60-year temperature anomaly, and chandler wobble envelope reproduces the form of the 60-year oscillation noticed in GMSL. The quasi 20-year oscillation observed in GMSL is correlated with the chandler wobble excitation. So, we assume that Earth＇s rotation and climate indexes are connected. Despite of all the clues hinting this connection, no sound conclusion can be done as far as ocean circulation modelling is not able to correctly catch angular momentum of the oscillatory modes.

关键词： Earth rotation climate change Sea level Multichannel singular spectrumanalysis (MSSA) North Atlantic Oscillation (NAO) Atlantic Multi-decadal Oscillation(AMO)

Antarctic-wide annual ice flow maps from Landsat 8 imagery between 2013 and 2019

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2021年第5期14卷 597-618页

作者： Qiang Shen Hansheng Wang c.k.shum Liming Jiang Houtse Hsu Fan Gao Yingli Zhao State key Laboratory of Geodesy and Earth’s Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhanPeople’s Republic of China Division of Geodetic Science School of Earth SciencesThe Ohio State UniversityColumbusOhioUSA college of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijingPeople’s Republic of China

Ice velocity constitutes a key parameter for quantifying ice-sheet discharge rates and is thus crucial for improving the coupled models of the Antarctic ice sheet towards accurately predict its contribution to future global sea-level ***,in Antarctica,high-resolution and continuous ice velocity estimates remain elusive,which is key to unravel Antarctica’s present-day ice mass balance ***,we present a suite of newly estimated Antarctic-wide,annually-sampled ice velocity products at 105-m grid-spacing observed by Landsat 8 optical images *** first describe a procedure that can automatically calibrate and integrate ice displacement maps to generate Antarcticwide seamless ice velocity *** annual ice velocity mosaics are assembled using a total of 250,000 displacement maps inferred from more than 80,000 Landsat 8 images acquired between December 2013 and April *** new annual Antarctic ice velocity data product exhibits an improved quantification of near-decadal Antarctic-wide ice flow,and an opportunity to investigate ice dynamics at a higher spatial resolution and annual sampling,as compared to existing data *** studies confirmed improved accuracy and consistency of this new data product,when compared with independently estimated optical and radar ice velocity data products,as well as in situ data.

关键词： Antarctica ice velocity Landsat 8