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Source mechanism of strong aftershocks (M_s≥5.6) of the 2008/05/12 Wenchuan earthquake and the implication for seismotectonics

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science china Earth sciences 2009年第6期52卷 739-753页

作者： ZHENG Yong1,2,MA HongSheng3.Lü Jian4,NI SiDao5,LI YingChun6 & WEI ShengJi2 1 institute of Geodesy and Geophysics,chinese Academy of sciences,Wuhan 43.077,{3. 2 institute of Geophysics,chinese Earthquake administration,beijing 100086,{3. 3.institute of Earthquake science,chinese Earthquake administration,beijing 100086,{3. 4 Earthquake administration of Jiangxi Province,Nanchang 3.003.,{3. 5 School of Earth and Space science,University of science and Technology of {3.,Hefei 23.026,{3. 6 Earthquake administration of Jiangsu Province,Nanjing 210014,{3. 1. institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China 2. institute of Geophysics Chinese Earthquake Administration Beijing 100086 China 3. institute of Earthquake science Chinese Earthquake Administration Beijing 100086 China 4. Earthquake administration of Jiangxi Province Nanchang 330039 China 5. School of Earth and Space science University of Science and Technology of China Hefei 230026 China 6. Earthquake administration of Jiangsu Province Nanjing 210014 China

Dozens of >M5, hundreds of >M4, and much more >M3.aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3.aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedrocks. Then we collected waveform data from National Digital Seismograph Network and regional seismograph network of china, and employed 'Cut and Paste' method to obtain focal mechanisms and depths of the big aftershocks (M≥5.6). While most of those aftershocks show thrust mechanism, there are some strike slip earthquakes in the northern-most end of the rupture. Focal mechanisms show that the events located on the southern part of central Beichuan-Yingxiu Fault (BY) are mainly thrust earthquakes, which is consistent with initial mechanism of the main shock rupture. In the north part the aftershocks along the BY are also dominated by thrust slip, which is quite different from the right slip rupture of the main shock. Around Qingchuan-Pingwu Fault, the focal mechanisms are dominated by right-slip rupture with large depths (~18 km). So we suspected that in the north part the main shock might rupture on two faults: Beichuan Fault and Qingchuan-Pingwu Fault. The complex pattern of aftershock mechanisms argues for presence of a complicated fault system in the Longmenshan area.

关键词： focal mechanism seismotectonics Wenchuan earthquake cut and paste.

^(40)Ar/^(3.)Ar dating of shear deformation of the Xianshuihe fault zone in west Sichuan and its tectonic significance

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science china Earth sciences 2004年第9期47卷 794-803页

作者： ZHANG Yueqiao1, CHEN Wen2, 3.& YANG Nong1 1. institute of Geomechanics, chinese Academy of Geological sciences, {3. 100081, china 2. institute of Geology, chinese Academy of Geological sciences, {3. 10003., china 3. institute of Geology and Geophysics, chinese Academy of sciences, {3. 100029, china institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Based on field geological survey, structural measurements and classical Ar/Ar dating of mica, biotite and K-feldspar, we obtain cooling ages for Miocene left-lateral shear along the Xianshuihe fault zone. The results document two thermal events during the sinistral shear. The early event (12-10 Ma) corresponds to rapid cooling of the Zheduoshan granitic massif from above 700℃ to below 3.0℃. The late event (5-3.5 Ma) corresponds to cooling of granites intruded along the eastern side of the fault zone. These dating results provide important thermochronological constraint on the timing of late Cenozoic eastward extrusion of the Chuan-Dian Block in the SE Tibetan margin.

关键词： Xianshuihe fault zone, Zheduoshan granitic massif, sinistral shear deformation, 40Ar/3.Ar dating, late Cenozoic.

Representation of microscale ocean wavenumber spectrum correct to the second order

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science china Earth sciences 2005年第4期48卷 549-554页

作者： YUAN Yeli2 & HUA Feng1,2,3.1. institute of Oceanology, chinese Academy of sciences, Qingdao 266071, {3. 2. Key Laboratory of Marine science and Numerical Modeling, State Oceanic administration, Qingdao 266061, {3. 3. Graduate School of the chinese Academy of sciences, beijing 10003., {3. 1. Key Laboratory of Marine science and Numerical Modeling State Oceanic Administration 266061 Qingdao China 2. institute of Oceanology Chinese Academy of Sciences 266071 Qingdao China 3. Graduate School of the chinese Academy of sciences 100039 Beijing China

In this paper, the analytical representations of four wave source functions in high-frequency spectrum range are given on the basis of ocean wave theory and dimensional analysis, and the perturbation method is used to solve the governing equations of ocean wave high-frequency spectrum on the basis of the temporally stationary and locally homogeneous scale relations of microscale wave. The microscale ocean wavenumber spectrum correct to the second order has an explicit structure, its first order part represents the equilibrium between dif- ferent source functions, and its second order part represents the contribution of microscale wave propagation.

关键词： temporally stationary and locally homogeneous, source function in high-frequency spectrum range, microscale ocean wavenumber spectrum.

Integrated precise orbit determination of Shenzhou IV unmanned spacecraft

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science china(Technological sciences) 2004年第5期47卷 518-525页

作者： L Congmin1,2, GU Yidong3. LIN Baojun3.& GUO Jiong3.1. Center for Space science and Applied Research, chinese Academy of sciences, {3. 100080, china 2. Graduate School of the chinese Academy of sciences, {3. 10003., china 3. General Establishment of Space science and Application, chinese Academy of sciences, {3. 100080, china Correspondence should be addressed to L Congmin 1. Center for Space science and Applied Research Chinese Academy of Sciences 100080 Beijing China 2. Graduate School of the chinese Academy of sciences 100039 Beijing China 3. General Establishment of Space science and Application Chinese Academy of Sciences 100080 Beijing China

Considering the characteristic orbit of Shenzhou IV spacecraft and the advantages and disadvantages of several types of domestic orbit measurements, a scheme of IPOD is determined, which uses GPS, SLR and USB observation data jointly plus precise ionosphere corrections to GPS observation data. IPOD system and mathematic models of OD are introduced. The results of different joint OD are analyzed using true observation data, and show that radial accuracy is better than 2 m.

关键词： Shenzhou IV unmanned spacecraft integrated precise orbit determination GPS SLR USB.

Two possible mechanisms for vortex self-organization

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science china Earth sciences 2006年第2期49卷 202-211页

作者： LUO Zhexian2, ZHOU Xiuji1 & GAO Shouting3.1. chinese Academy of Meteorological sciences, beijing 100081, {3. 2. Department of Space Information science, Nanjing University of Information science and Technology, Nanjing 210044, {3. 3. institute of Atmospheric Physics, chinese Academy of sciences, beijing 100029, {3. 2. Department of Environmental science Nanjing University of Information Science and Technology Nanjing 210044 China 1. chinese Academy of Meteorological sciences Beijing 100081 China 3. institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The vortex self-organization is investigated in this paper by four groups of numerical experiments within the framework of quasi-geostrophic model, and based on the experimental results two types of possible mechanisms for vortex self-organization are suggested. The meso-scale to-pography may enable separated vortices to merge into a larger scale vortex; and the interaction of meso-γ and meso-β scale systems may make separated vortices to self organize a typhoon-like vor-tex circulation.

关键词： vortex, self-organization, meso-scale topography, interaction of different scales.

Approximation of dense-n/2-subgraph and table compression problems

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science china Mathematics 2005年第9期48卷 1223-1233页

作者： XU Dachuan~1 HAN Jiye~2 & DU Dongle~3.1. College of Applied sciences,beijing University of Technology,beijing 100022,{3. 2. institute of Applied Mathematics,Academy of Mathematics and Systems science,chinese Academy of sciences,beijing 100080,{3. 3. Faculty of administration,University of New Brunswick,P.O.Box 4400,Fredericton,NB E3. 5A3.Canada College of Applied sciences Beijing University of Technology Beijing 100022 China institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Faculty of administration University of New Brunswick P.O. Box 4400 Fredericton NB E3B 5A3 Canada

We develop improved approximation algorithms for two NP-hard problems: the dense-n/2-subgraph and table *** on SDP relaxation and advanced rounding techniques,we first propose 0. 5982 and 0. 5970-approximation algorithms respec- tively for the dense-n/2-subgraph problem (DSP) and the table compression problem (TCP). Then we improve these bounds to 0. 6243.and 0. 6708 respectively for DSP and TCP by adding triangle inequalities to strengthen the SDP *** results for TCP beat the 0. 5 bound of a simple greedy algorithm on this problem,and hence answer an open question of Anderson in an affirmative way.

关键词： dense-n/2-subgraph problem(DSP) table compression problem(TCP) SDP approximation ratio

A mixed method for measuring low-frequency acoustic properties of macromolecular materials

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science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 729-739页

作者： LIU Hongwei1,YAO Lei1,3.ZHAO Hong1,3.ZHANG Jichuan2,3.& XUE Zhaohong2 1. National Key Laboratory of Acoustics,institute of Acoustics,chinese Academy of sciences,{3. 100080,china 2. institute of Chemistry,chinese Academy of sciences,{3. 100080,china 3. Graduate University of chinese Academy of sciences,{3. 100049,china National Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing 100080 China institute of Chemistry Chinese Academy of Sciences Beijing 100080 China Graduate University of chinese Academy of sciences Beijing 100049 China

A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequen-cies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super-position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis. To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method. While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorp-tion coefficients is obtained between the calculations and measurements in the acoustic pipe.

关键词： low-frequency acoustic properties,dynamic mechanical properties,Principles of Time-Temperature Superposition,acoustic pipe,sound absorption coefficient.

Effect of rock mass structure and block size on the slope stability——Physical modeling and discrete element simulation

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science china(Technological sciences) 2005年第z1期48卷 1-17页

作者： LI Shihai1, LIAN Zhenzhong1,2 & J. G. Wang3.1. institute of Mechanics, chinese Academy of sciences, {3. 100080, china 2. Graduate School, chinese Academy of sciences, {3. 100060, china 3. Tropical Marine science institute, National University of Singapore, Singapore 119260 chinese Acad Sci Inst Mech Beijing 100080 Peoples R China chinese Acad Sci Grad Sch Beijing 100060 Peoples R China Natl Univ Singapore Trop Marine Sci Inst Singapore 119260 Singapore

This paper studies the stability of jointed rock slopes by using our improved three-dimensional discrete element methods (DEM) and physical modeling. Results show that the DEM can simulate all failure modes of rock slopes with different joint configurations. The stress in each rock block is not homogeneous and blocks rotate in failure development. Failure modes depend on the configuration of joints. Toppling failure is observed for the slope with straight joints and sliding failure is observed for the slope with staged joints. The DEM results are also compared with those of limit equilibrium method (LEM). Without considering the joints in rock masses, the LEM predicts much higher factor of safety than physical modeling and DEM. The failure mode and factor of safety predicted by the DEM are in good agreement with laboratory tests for any jointed rock slope.

关键词： rock masses, slope stability, DEM simulation, block size effect, joints configuration effect, limit equilibrium method.

Discovery of immune related factors in Fenneropenaeus chinensis by annotation of ESTs

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Progress in Natural science:Materials International 2004年第1期14卷 48-55页

作者： SHEN Yaoqing 1,2 , XIANG Jianhai 1*, WANG Bing 1,2 , LI Fuhua 1 and TONG Wei 3.1. Experimental Marine Biology Laboratory, institute of Oceanology, chinese Academy of sciences, Qingdao 266071,{3. 2. Graduate School of the chinese Academy of sciences, beijing 10003., {3. 3. Genomics & Bioinformatics institute, chinese Academy of sciences, beijing 1013.0, {3.) chinese Acad Sci Inst Oceanol Expt Marine Biol Lab Qingdao 266071 Peoples R China chinese Acad Sci Grad Sch Beijing 100039 Peoples R China chinese Acad Sci Geonom & Bioinformat Inst Beijing 101300 Peoples R China

A total of 10446 expressed sequence tags (ESTs) are obtained by a large scale sequencing of a cDNA library from cephalothorax of adult Fenneropenaeus chinensis . An EST analysis platform was built up based on local computers and bioinformatic techniques were used to annotate these ESTs in order to promptly find possible functional genes, especially for immune related factors. About 4% of the ESTs show similarity to the coding sequences of such factors, including lectin, serine protease, serpin, lysozyme, etc. These ESTs provide a partial profile of the immune system in F. chinensis and useful information for further study on these genes.

关键词： Fenneropenaeus chinensis bioinformatics ESTs immune factors