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Seismic wave propagating in Kelvin-Voigt homogeneous visco-elastic media

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Science china Earth Sciences 2006年第2期49卷 147-153页

作者： YUAN Chunfang1, PENG Suping1, ZHANG Zhongjie2 & LIU Zhenkuan3.1. china University of Mining & Technology, beijing 100083. china 2. {3. of Geophysics, Chinese Academy of Sciences, beijing 100101, china 3. Exploration and Development Research {3. of Daqing Oilfield, Daqing 163.12, china 1. china University of Mining & Technology Beijing 100083 China 2. institute of Geophysics Chinese Academy of Sciences Beijing 100101 China 3. Exploration and Development Research institute of Daqing Oilfield Daqing 163712 China

This paper studies, under a small disturbance, the responses of seismic transient wave in the visco-elastic media and the analytic solution of the corresponding third-order partial differential equation. A plane wave solution of Kelvin-Voigt homogeneous visco-elastic third-order partial differ-ential equation with a pulse source is obtained. By the principle of pulse stacking of particle vibration, the result is extended to the solution of Kelvin-Voigt homogeneous visco-elastic third-order partial differential equation with any source. The velocities of seismic wave propagating and the attenuation of seismic wave in Kelvin-Voigt homogeneous visco-elastic media are discussed. The velocities of seismic wave propagating and the coefficient of attenuation of seismic wave in Kelvin-Voigt homogeneous visco-elastic media are derived, expressed as functions of density of the media, elastic modulus and visco-elastic coefficient. These results can be applied in inversing lithology parameters in geophysical prospecting.

关键词： Kelvin-Voigt visco-elastic velocity attenuation seismic wave.

Existence of the solutions and the attractors for the large-scale atmospheric equations

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Science china Earth Sciences 2006年第6期49卷 650-660页

作者： HUANG Haiyang1 & GUO Boling2 1. Department of Mathematics, beijing Normal University, beijing 100875, china 2. {3. of applied Physics and Computational Mathematics, beijing 100080, china 1. Department of Mathematics Beijing Normal University Beijing 100875 China 2. institute of applied Physics and Computational Mathematics Beijing 100080 China

In this paper, firstly, the proper function space is chosen, and the proper expression of the operators is introduced such that the complex large-scale atmospheric motion equations can be described by a simple and abstract equation, by which the definition of the weak solution of the atmospheric equations is made. Secondly, the existence of the weak solution for the atmospheric equations and the steady state equations is proved by using the Galerkin method. The existence of the non-empty global attractors for the atmospheric equations in the sense of the Chepyzhov-Vishik’s definition is obtained by constructing a trajectory attractor set of the atmospheric motion equations. The result obtained here is the foundation for studying the topological structure and the dynamical behavior of the atmosphere attractors. Moreover, the methods used here are also valid for studying the other atmospheric motion models.

关键词： atmosphere equations, weak solution, trajectory attractor, global attractor, equilibrium.

Climate effects of nuclear war in china

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Journal of Environmental Sciences 1993年第2期5卷 230-240页

作者： Cao HongxingChinese Academy of Meteorological Sciences, beijing 100081, chinaWang Yongzhong Lin Yunmeibeijing {3. of meteorology, beijing 100081, china Chinese Academy of Meteorological Sciences Beijing 100081 China. China

By utilizing simulations of climatic respponse to nuclear smoke, which were made by the Lawrence Livermore National Laboratory, USA, climate change in china induced by a large-scale nuclear war is analysed. Remarkable climate change in china following nuclear smoke injections is found. The surface air temperature decreases dramatically around all china, surface cooling is 13.℃ averaging over whole china in July and maximum cooling is 23. 4 ℃ , 3.℃ cooling in January and maximum 8℃ for the 150 Tg smoke injection (equivalent to the base-line nuclear war). However, the change in temperature is unhomogeneous, implying that the rise in temperature happens over some parts of china. An averaging precipitation decrease in many of months of the experimental year. The precipitation defect is dependent on a scale of nuclear war, the deduction is 1.8mm/day averaging over china in July in the 150 Tg smoke injection, and 0.1 mm/d in January. Nevertheless, the precipitation enhancement in a few months over some regions is found. This dramatic climate change brings catastrophe to agriculture, ecology, as well as socio-economics.

关键词： nuclear winter climate simulation precipitation change.

Numerical simulation of strain localization and damage evolution in large plastic deformation using mixed finite element method

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Journal of University of Science and Technology beijing 2004年第3期11卷 273-277页

作者： Zhanghua Chen Jiajian Jin Jiumei Xiao applied Science School, University of Science and Technology beijing, beijing 100083.{3. applied Science School University of Science and Technology Beijing Beijing 100083 China

An investigation of computer simulation is presented to analyze the effectsof strain localization and damage evolution in large plastic deformation. The simulation is carriedout by using an elastic-plastic-damage coupling finite element program that is developed based onthe concept of mixed interpolation of displacement/pressure. This program has been incorporated intoa damage mechanics model as well as the corresponding damage criterion. To illustrate theperformance of the proposed approach, a typical strain localization problem has been simulated. Theresults show that the proposed approach is of good capability to capture strain localization andpredict the damage evolution.

关键词： strain localization mixed element truesdell stress rate material damage

A New Method for Fractal Dimension Determination by STM at Nanometer Scale

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 64-68页

作者： Qikai Li Yue Zhang Wuyang Chu Chen Wang Chunli Bai (applied Science School. University of Science and Technology beijing, beijing 100083.{3.)(Chemical institute, Chinese Academy of Science, beijing 100080.{3.) applied Science School University of Science and Technology Beijing Beijing 100083 China Chemical institute Chinese Academy of Science Beijing 100080 China

A new method for determining the fractal dimension by STM at nanomeler scale has been ***- Mandelbrot fractal curves were used to verify the accuracy and reliability. The Computer simulation showed that fractal dimen- sion obtained with this method generally outran the traditional yard method. The new method has been applied to the fractal dimension determination of the fractures of Ti3.l and Ti-24Al-11Nb alloys. The results show that the fractal dimension of Ti-24Al-11Nb alloy is higher than that of Ti3.l, and it varies with the crark extending orientation.

关键词： fractal dimension STM nanometer scale Ti-Al alloy

Chaotic attitude and reorientation maneuver for completely liquid-filled spacecraft with flexible appendage

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Acta Mechanica Sinica 2009年第2期25卷 271-277页

作者： B. Yue Department of Mechanics, School of Science,beijing institute of Technology, 100081 beijing,{3. Department of Mechanics School of Science Beijing Institute of Technology 100081 Beijing China

The present paper investigates the chaotic attitude dynamics and reorientation maneuver for completely viscous liquid-filled spacecraft with flexible appendage. All of the equations of motion are derived by using Lagrangian mechanics and then transformed into a form consisting of an unperturbed part plus perturbed terms so that the system＇s nonlinear characteristics can be exploited in phase space. Emphases are laid on the chaotic attitude dynamics produced from certain sets of physical parameter values of the spacecraft when energy dissipation acts to derive the body from minor to major axis spin. Numerical solutions of these equations show that the attitude dynamics of liquid-filled flexible spacecraft possesses characteristics common to random, non- periodic solutions and chaos, and it is demonstrated that the desired reorientation maneuver is guaranteed by using a pair of thruster impulses. The control strategy for reorientation maneuver is designed and the numerical simulation results are presented for both the uncontrolled and controlled spins transition.

关键词： Nonlinear attitude dynamics Attitude reorientation maneuver Control strategyLiquid-filled spacecraft

A fiducial argument for generalized p-value

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Science china Mathematics 2007年第7期50卷 957-966页

作者： Xin-min LI~(1+) Xing-zhong XU~2 Guo-ying LI~3.1 institute of applied Mathematics,Shandong University of Technology,Zibo 255049,china 2 Department of Mathematics,{3. institute of Technology,{3. 100801,china 3.Academy of Mathematics and Systems Science,Chinese Academy of Sciences,{3. 100800,china institute of applied Mathematics Shandong University of Technology Zibo 255049 China Department of Mathematics Beijing Institute of Technology Beijing 100801 China Academy of Mathemtics Systems Science Chinese Academy of Sciences Beijing 100800 China

This paper provides a general method for constructing generalized p-value via the fiducial ***,the power properties of the generalized test are *** illustrations, the two-parameter exponential distribution and unbalan... 详细信息

关键词： fiducial distribution generalized p-value frequency property two-parameter exponential distribution variance component 62F03 62E15

ON THE LINEAR CONVERGENCE OF PC-METHOD FOR ACLASS OF LINEAR VARIATIONAL INEQUALITIES

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Journal of Computational Mathematics 1999年第2期17卷 199-208页

作者： Nai-hua Xiu(Department of Mathematics, Nothern Jiaotong University, beijing 100044, china instituteof {3. Mathematics, Chinese Academy Of Sciences, beijing 100080, china) 北方交通大学数学系北京

This paper studies the linear convergence properties of a class of the projection and contraction methods for the affine variational inequalities, and proposes a necessary and sufficient condition under which PC-Metho... 详细信息

关键词： affine variational inequality projection and contraction method linear convergence

Absolute Stability of General Lurie Control Systems with Multi-Nonlinear Feedback Terms

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Acta Mathematica Sinica,English Series 2001年第4期17卷 649-656页

作者： Zuo Xin GAN Wei Gao GE institute of Systems Science, Chinese Academy of Sciences, beijing 100080, P. R. china Department of {3. Mathematics, beijing institute of Technology, beijing 100081, P. R. china institute of Systems Science Chinese Academy of Sciences Beijing 100080 P. R. China Department of applied Mathematics Beijing Institute of Technology Beijing 100081 P. R. China

In this paper, the problenl of absohlte stability for general Lurie control systems with multi- nonlinear feedback terms is investigated. From the Lyapunov function approach. new necessary and sufficient conditious and some practical sufficient conditions of absolute stability are derived. which improve the absolute stability for the set. A numerical examplc illustrates the effectiveness of the proposed results.

关键词： General Lurie system Multi-nonlinear feedback Absolute stability