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The numerical method for three-dimensional impact with friction of multi-rigid-body system

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Science China(Physics,Mechanics & Astronomy) 2006年第1期49卷 102-118页

作者： ZHAO Zhen1,2. LIU Caishan2.& CHEN Bin2.1. beijing Institute of Graphic Communication, beijing 102.00, China 2. {2. of Mechanics & Engineering Science,{3., beijing 100871, China beijing Institute of Graphic Communication Beijing 102600 China department of Mechanics & Engineering Science Peking University Beijing 100871 China

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid nu- merical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tan- gential movement modes varied with the normal impulse during collision.

关键词： multi-rigid body, impact, friction.

ESTIMATING EXTREME-VALUE INDEX FROM RECORDS

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Chinese Annals of Mathematics,Series B 1998年第4期19卷 499-510页

作者： QI YONGCHENG (department of Probability & Statistics, peking university,{2., China.) peking Univ Dept Stat & Probabil Beijing 100871 Peoples R China

This paper constructs from the record values an estimator of the extreme-value index. It is proved that the estimator is consistent in the domain of attraction of extremesvalue distributions, and that under very mild ... 详细信息

关键词： Record Extreme value distribution Estimator Consistency Asymptotic normality

Design of a new dynamical core for global atmospheric models based on some efficient numerical methods

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Science China Mathematics 2004年第z1期47卷 4-21页

作者： WANG Bin, WAN Hui, Jl Zhongzhen, ZHANG Xin, YU Rucong, YU Yongqiang & LIU HongtaoState Key Laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics, Institute of atmospheric Physics, Chinese Academy of sciences, beijing 10002., China department of Computational Mathematics, Academy of Mathematics and System sciences, peking university, beijing 100871, China Chinese Acad Sci Inst Atmospher Phys State Key Lab Numer Modeling Atmospher Sci & Geop Beijing 100029 Peoples R China peking Univ Acad Math & Syst Sci Dept Computat Math Beijing 100871 Peoples R China

A careful study on the integral properties of the primitive hydrostatic balance equations for baroclinic atmosphere is carried out, and a new scheme todesign the global adiabatic model of atmospheric dynamics ispresented. This scheme includes a method of weighted equal-areamesh and a fully discrete finite difference method with quadraticand linear conservations for solving the primitive equationsystem. Using this scheme, we established a new dynamical corewith adjustable high resolution acceptable to the availablecomputer capability, which can be very stable without anyfiltering and smoothing. Especially, some important integralproperties are kept unchanged, such as the anti-symmetries of thehorizontal advection operators and the vertical convectionoperator, the mass conservation, the effective energy conservationunder the standard stratification approximation, and so on. Somenumerical tests on the new dynamical core, respectively regardingits global conservations and its integrated performances inclimatic modeling, incorporated with the physical packagesfrom the Community atmospheric Model Version 2.(CAM2. of NationalCenter for atmospheric Research (NCAR), are included.

关键词： dynamical core, equal-area mesh, anti-symmetry, effective energy conservation.

A general information theoretical proof for the second law of thermodynamics

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Science China(Physics,Mechanics & Astronomy) 2008年第7期51卷 813-816页

作者： ZHANG QiRen department of Technical Physics, peking university,{2., China 1. department of Technical Physics Peking University Beijing 100871 China

It is shown that the conservation and the non-additivity of the information, together with the additivity of the entropy, make the entropy increase in an isolated system. The collapse of the entangled quantum state offers an example of the information non-additivity. Nevertheless, the non-additivity of information is also true in other fields in which the interaction information is important. Examples are classical statistical mechanics, social statistics and financial processes. The second law of thermodynamics is thus proven in its most general form. It is exactly true not only in quantum and classical physics but also in other processes in which the information is conservative and non-additive.

关键词： information conservation non-additivity of information entropy increase

Progress in cognitive neuroscientific studies of visual awareness

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Progress in Natural Science:Materials International 2009年第2期19卷 145-152页

作者： Qi Li,Haiyan Geng department of Psychology,peking {2.,{3. 100871,China [a]department of Psychology Peking University Beijing 100871 China

The psychological and neural mechanisms of consciousness are among the most baffling problems in cognitive neuroscience. In this field,visual awareness is a topic that has been largely investigated,due to easy manipulation and measurable effects. The present arti-cle begins with the phenomena of dissociations between visual awareness and visual stimulus,visual awareness and visual attention,as well as visual awareness and vision-guided behavior,along with the corresponding experimental evidence. Furthermore,the neural mechanism of visual awareness is also discussed. It has been generally believed that visual awareness is the function of higher-order cerebral areas; however,recent discoveries have demonstrated that feedback from higher-to lower-order cortex areas is necessary for generating consciousness. The present article presents an in-depth analysis regarding this feedback process,and exploring its relation-ship with the generation and mechanisms of consciousness. Finally,theoretical controversies and discrepancies,as well as result con-flicts from various studies,have been collected,compared and discussed. Because the field of consciousness continues to be an extremely mysterious and complicated psychological phenomenon,there is a great need for further studies to explore and clarify this topic.

关键词： Visual awareness Neural mechanism Feedback process Cortical areas

A　CONVENIENT　METHOD　FOR　SYNTHESIZING　AND　CHARACTERIZATION　OF　（Z）－ALKENOLS　AND　THEIR　ACETATES

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Chinese Chemical Letters 1995年第11期6卷 943-944页

作者： Gu YUAN(department of Chemistry,peking {2.,{3.) beijing Univ Dept Chem Beijing 100871 Peoples R China

All double bond positional isomers of (Z)-dodecenol, (Z)-tetradecenol, (Z)hexadecenol and their acetates were synthesized by the Wittig reaction and the coupling reaction, and a novel procedure for the identification ...

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Some properties on multivariate filter banks with a matrix factorization

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Progress in Natural Science:Materials International 2005年第2期15卷 20-30页

作者： LIAN Qiaofang1, XIAO Hongying2. and CHEN Qiuhui3.1. department of Mathematics, {2. Jiaotong {2., {2. 100044, China 2. Institute of Mathematics, Academy of Mathematics and System sciences, Chinese Academy of sciences, {2. 100080, China 3. department of Scientific Computing and Computer Applications, Zhongshan {2., Guangzhou 5102.5, China) department of Mathematics Beijing Jiaotong University Beijing 100044 China. Institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China. department of Scientific Computing and Computer Applications Zhongshan University Guangzhou 510275 China

A class of multivariate filter banks with a matrix factorization has been developed by Chen et al. The main purpose of this paper is to discuss some further properties of this kind of filter bank, such as the completeness, accuracy of the corresponding scaling functions and the relationships with Daubechies' wavelets and the multi-wavelets provided by Chui and Lian. Moreover, some examples are given to show that this kind of filter bank has a higher accuracy for the scaling functions.

关键词： filter banks completeness accuracy matrix factorization

Speciation of the elements and compositions on the surfaces of dust storm particles:The evidence for the coupling of iron with sulfur in aerosol during the long-range transport

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Chinese Science Bulletin 2005年第8期50卷 738-744页

作者： ZHANG Xingying1,2. ZHUANG Guoshun1,2.3. CHEN Jianmin2.& XUE Huaxin2.1. Center for atmospheric Environment Study, {2. of Chemistry, {2. Normal {3., {2. 100875, China 2. Center for atmospheric Chemistry Study, {2. of Environ- mental Science and Engineering, Fudan {3., Shanghai 2.043., China 3. LAPC/NZC, Institute of atmospheric Physics, NZC/LAPC, Chinese Academy of {12., {2. 10002., China Center for atmospheric Environment Study Department of Chemistry Beijing Normal University Beijing 100875 China Center for atmospheric Chemistry Study Department of Environmental Science and Engineering Fudan University Shanghai 200433 China LAPC/NZC Institute of Atmospheric Physics NZC/LAPC Chinese Academy of Sciences Beijing 100029 China

The speciation of the elements on the surface of the particles collected during dust storm and non-dust storm in beijing and Inner Mongolia was studied by XPS. The ma- jor species of iron on the surface were oxides, sulfate, silicate, FeOOH and minor part sorbed on SiO2.Al2.3. Sulfate is the dominant species of sulfur on the surface. SiO2.and Al2.3.are the main components of Si and Al on the surface respectively. One of the most important findings was that the Fe(II) (FeS and FeSO4) produced could account for up to 44.3. and 45.6% of the total Fe on the surface in the aerosol sample collected at that night and next day of the “peak” time of the dust storm occurring on March 2., 2.02. while Fe2.SO4)3. one of the Fe(III) species on the surface decreased from 67.1% to 49.5% and 48.0% respectively. Both S and Fe en- riched on the surface of aerosol particles. Fe(II) accounted for 1.3.?5.3. of total Fe in bulk aerosol samples during dust storm. These results provided strong evidence to sup- port the hypothesis of the coupling between iron and sulfur in aerosols during the long-range transport, which would have important impact on the global biogeochemical cycle.

关键词：物种形成原理 XPS 大气悬浮物 Fe-S结合粒子集合

Generalized Chow Forms and Reduction of Semi-Stable Varieties

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Acta Mathematica Sinica,English Series 2000年第2期16卷 219-228页

作者： Qingchun Tian department of Mathematics,peking {2.,{3. 100871,P.R.China department of Mathematics Peking University Beijing 100871 P. R. China

In this note,by using the method of ***[1],we obtain the local version of a theorem of BGS[2.which links Faltings heights of projective varieties with the Philippon heights for the corresponding generalized Chow *** the stable reduction theorem of ***[1],we prove that Chow semistabilities and generalized Chow semistabilities are the same.

关键词： Deligne Pairing Faltings Height Chow forms