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Hyperbolic positive mass theorem under modified energy condition

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Science china Mathematics 2008年第12期51卷 2189-2197页

作者： XIE NaQing institute of Mathematics, School of Mathematical sciences, Fudan University, Shanghai 200433, china institute of Mathematics School of Mathematical Sciences Fudan University Shanghai 200433 China

We provide two new positive mass theorems under respective modified energy conditions allowing T00 negative on some compact set for certain modified asymptotically hyperbolic manifolds. This work is analogous to Zhang... 详细信息

关键词： positive mass theorem modified energy condition modified asymptotically hyperbolic 83C40 53C27

Workspace and rotational capability analysis of a spatial 3-DoF parallel manipulator

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Progress in Natural Science:Materials International 2004年第11期 60-67页

作者： LIU Xinjun 1*, WANG Jinsong 1, WANG Qiming 2 and LI Tiemin 1(1. Manufacturing Engineering institute, Department of Precision Instruments, Tsinghua University, beijing 100084, china 2. National Astronomical Observatories, chinese academy of sciences, beijing 100012, china) ManufacturingEngineeringinstitute DepartmentofPrecisionInstrumentsTsinghuaUniversityBeijing100084China NationalAstronomicalObservatories ChineseAcademyofSciencesBeijing100012China

The analysis on the workspace and rotational capability of HANA, a spatial 3-DoF parallel manipulator, is concerned. The parallel manipulator consists of a base plate, a movable platform, and three connecting legs. The moving platform has three degrees of freedom (DoFs) which are two translations and one rotation, with respect to the base plate. The new parallel manipulator is very interesting for the reason of no singularity in the workspace, the single-DoF joint architecture and high rotational capability of the moving platform. The inverse kinematics problem is described in a closed-form, which is very useful to present the workspace geometrically. The constant-orientation and reachable workspaces for the manipulator are analyzed firstly. The index that is used to evaluate the rotational capability of the manipulator is defined and discussed in detail. Finally, the distribution of rotational capability index on the workspace is presented, which helps us know how much the index is at different point. The parallel manipulator has wide application in the fields of industrial robots, simulators, micro-motion manipulators, and parallel kinematics machines.

关键词： parallel manipulator singularity rotational capability workspace kinematics.

Expression of inhibin a and βA subunits in cultured human first trimester trophoblast tissue

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chinese Science Bulletin 1997年第2期42卷 174-175页

作者： YANG Xinlin, HAN Chunsheng, ZHANG Zhiwen and ZHUANG LinzhiState Key Laboratory of Reproductive Biology, institute of Zoology, chinese academy of sciences, beijing 100080, china

TWO protein hormones, which are dominantly produced by the gonads, are termed inhibin and aetivin since they can inhibit and stimulate the secretion of follicle-stimulating hormone (FSH) by anterior pituitary gland. They are also found in human placenta, and may regulate the placental hormonal secretion. However, control of inhibin subunit expression is not yet reported in human first trimester placenta. Here, using solution hybridization/nuclease protect assay, we determine expression of inhibin a and βA subunits in serum-free cultured trophoblast tissue from human first trimester placenta (6-9 week).

关键词： RNA Expression of inhibin a and A subunits in cultured human first trimester trophoblast tissue

GENERALIZED REVERBERATION MATRIX FORMULATION FOR WAVE PROPAGATION IN MULTILAYERED MEDIUM

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Acta Mechanica Solida Sinica 2010年第3期23卷 189-199页

作者： Jiayong Tian~★(institute of Crustal Dynamics,china Earthquake Administration,P.O.Box 2855,beijing 100085,china) [a] (institute of Crustal Dynamics China Earthquake Administration P.O. Box 2855 Beijing 100085 China)

Generalized reverberation matrix （GRM） formulation is presented to investigate elastic wave propagation in a complex multilayered solid by the combination of reverberation-ray matrix （RRM） method and stiffness matrix （SM） method. RRM method formulates a reverberation matrix, which reflects the reflection or refraction of the elastic waves in the multilayered solid. However, the dimension of RRM increases as the sublayer number increases, which may result in lower calculation efficiency of the generalized rays. SM formulation yields a system matrix of the constant dimension to promise higher calculation efficiency, but it is difficult to identify the generalized rays. In order to calculate the generalized rays in the complex multi-layered solid efficiently, the RRM formulation is applied to the interested sublayer for the evaluation of the generalized rays and SM formulation to the other sublayers, to construct a generalized reverberation matrix of the constant dimension, which is independent of the sublayer number. Numerical examples show that GRM formulation has higher calculation efficiency for the generalized rays in the complex multilayered-solid configuration compared with RRM formulation.

关键词： elastic waves multilayered medium generalized reverberation matrix stiffness matrix

SOME REMARKS ON THE NULL CONDITION FOR NONLINEAR ELASTODYNAMIC SYSTEM

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chinese Annals of Mathematics,Series B 2002年第3期23卷 311-316页

作者： XIN JIE institute of Mathematics, Laboratory of Mathematics for Nonlinear sciences, Pudan University, Shanghai 200433, china. institute of Mathematics Laboratory of Mathematics for Nonlinear Sciences Fudan University Shanghai 200433 China

The author derives the same null condition as in [1] for the nonlinear elastodynamic system in a simpler way and proves the equivalence of the null conditions introduced in [1] and [7] respectively.

关键词： Null condition Stored energy function Elastodynamic system

Determining γ From Bs→Dπ

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Determining γ From Bs→Dπ

Sequencing and analysis of the giant panda genome

强子对撞机上的b物理研讨会

作者： Ying Li institute of high energy physics, CAS

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来源： cnki会议评论

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Science china(Life sciences) 2010年第8期53卷 1047-1048页

作者： YANG HuanMing BGI-Shenzhen (beijing Genomics institute Shenzhen), Shenzhen 518083, china 1. BGI-Shenzhen (beijing Genomics institute Shenzhen) Shenzhen 518083 China

The giant panda (Ailuropoda melanoleuca) is loved all over the world and is considered a symbol of china, as illustrated by its being one of the

关键词： Sequencing and analysis of the giant panda genome

A PROPOSAL FOR THE DEVELOPMENT OF SYNCHROTRON RADIATION FACILITIES IN china

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Bulletin of the chinese academy of sciences 1995年第3期9卷 242-246页

作者： Ding Dazhao and Jiang Xiaoming(beijing Electron-Positron Collider National Laboratory under the CAS institute of high-energy physics)

Synchrotron radiation is a powerful tool in research and application of physics, chemistry, biology, medicine, life science, micro-mechanics fabrication, and related disciplines. The history, current status, and future development of synchrotron radiation research and its application are discussed. A concrete proposal for constructing a third-generation synchrotron radiation source in china has been put forward.

关键词：五加坟山

SEISMIC STUDIES OF MARINE GAS HYDRATES

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化工学报 2003年第Z1期54卷 47-56页

作者： SONG Haibin (institute of Geology and Geophysics, CAS, beijing 100029, china) institute of Geology and Geophysics CAS Beijing 100029 China

We give a brief introduction of developments of seismic methods in the studies of marine gas hydrates. Then we give an example of seismic data processing for BSRs in western Nankai accretionary prism, a typical gas hydrate distribution region. Seismic data processing is proved to be important to obtain better images of BSRs distribution. Studies of velocity structure of hydrated sediments are useful for better understanding the distribution of gas hydrates. Using full waveform inversion, we successfully derived high-resolution velocity model of a double BSR in eastern Nankai Trough area. Recent survey and research show that gas hydrates occur in the marine sediments of the South china Sea and East china *** we would like to say seismic researches on gas hydrate in china are very preliminary.

关键词： gas hydrates, bottom-simulating reflector, seismic, full waveform inversion, Nankai Trough