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The Green formula and heredity of algebras

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Science china Mathematics 2005年第5期48卷 610-617页

作者： zhang Guanglian & WANG Shuai department of {2. sciences, Tsinghua University, beijing 100084, china Yancheng Teachers College, Yancheng 2.4002. china department of Mathematics, Johns Hopkins University, Baltimore, MD2.2.8, U.S.A. 1. department of mathematical {2. Tsinghua University 100084 Beijing China 2. Yancheng Teachers College 224002 Yancheng China 3. department of Mathematics Johns Hopkins University 21218 Baltimore MD USA

Let A be a finite dimensional algebra over a field k with q elements. It is shown that the Green formula is true in mod-A if and only if A is a hereditary algebra.

关键词： Green formula idempotent ideal hereditary algebra.

mathematical stencil and its application in finite difference approximation to the Poisson equation

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Science china Mathematics 2005年第10期48卷 1421-1429页

作者： FENG Hui~1 zhang Baolin~(1,2. & LIU Yang~1 1. department of Mathematics,Wuhan University,Wuhan 430072.{2. 2. Laboratory of Computational Physics,Institute of Applied Physics and Computational Mathematics,beijing 100088. {2. 1. department of Mathematics Wuhan University 430072 Wuhan China 2. Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics 100088 Beijing China

The concept of mathematical stencil and the strategy of stencil elimination for solving the finite difference equation is presented, and then a new type of the iteration algorithm is established for the Poisson equation. The new algorithm has not only the obvious property of parallelism, but also faster convergence rate than that of the classical Jacobi iteration. Numerical experiments show that the time for the new algorithm is less than that of Jacobi and Gauss-Seidel methods to obtain the same precision, and the computational velocity increases obviously when the new iterative method, instead of Jacobi method, is applied to polish operation in multi-grid method, furthermore, the polynomial acceleration method is still applicable to the new iterative method.

关键词： mathematical stencil, stencil elimination, Poisson equation, finite difference, iterative algorithm,parallelism.

Phase relationship of complex multi-component system in chromate cleaner production

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Progress in Natural Science:Materials International 2007年第7期17卷 845-850页

作者： Ge Xinlei~1 Wang Xidong~(1,3**) Zheng Shili~2.zhang Mei~1 zhang Yi~2.(1.{2. of Physical Chemistry,University of Science and Technology beijing,beijing 100083,china 2.Institute of Process Engineering,Chinese Academy of sciences,beijing 100080,china 3.College of Engineering,Peking University,beijing 100871,china) [a]department of Physical Chemistry University of Science and Technology Beijing Beijing China [b]College of Engineering Peking University Beijing China [c]Institute of Process Engineering Chinese Academy of Sciences Beijing China

The phase relationships of the complex multi-component systems in the liquid-phase oxidization and separation process related with the chromate cleaner production are investigated theoretically and *** phase diagram of main system Fe- Cr2.4-KOH-O2.f oxidization process and the relationship of its standard Gibbs free energy change with temperature are calculated.A se- ries of phase diagrams of the separation process at different temperatures,such as K（Na）OH-K（Na）2.rO4-H2.,KOH-KAlO2.H2., K（Na）OH-K（Na）2.O3-H2.,K（Na）OH-K（Na）HCO3-H2. and K（Na）HCO3-K（Na）2.rO4-H2. have also been *** ex- periments are carried out to verify the calculated *** results showed that the sub-molten salt media are suitable for the oxidization and separation processes;FeCr2.4can be oxidized across a wide range of temperature;K（Na）2.rO4can be separated from K（Na）AlO2.ystem at appropriate temperature and proper concentration;the crystallization of carbonate is easier than that of K（Na）2.rO4.

关键词： chromite chromate system thermodynamics calculation phase diagram

Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 496-512页

作者： LI Zhihui1,2. zhang Hanxin1 & FU Song2.⒈ National Laboratory for CFD, Hypervelocity Aerodynamics Institute,china Aerodynamics Research and Development Center,Mianyang 62.000,china 2.department of Engineering Mechanics,Tsinghua University,beijing 100084,china 1. National Laboratory for CFD Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center 621000 Mianyang China 2. department of Engineering Mechanics Tsinghua University 100084 Beijing China

The gas-kinetic unified algorithm using Boltzmann model equation have been extended and developed to solve the micro-scale gas flows in Poiseuille-like micro-channels from Micro-Electro-Mechanical Systems (MEMS). The numerical modeling of the gas kinetic boundary conditions suitable for micro-scale gas flows is presented. To test the present method, the classical Couette flows with various Knudsen numbers, the gas flows from short microchannels like plane Poiseuille and the pressure-driven gas flows in two-dimensional short microchannels have been simulated and compared with the approximate solutions of the Boltzmann equation, the related DSMC results, the modified N-S solutions with slip-flow boundary theory, the gas-kinetic BGK-Burnett solutions and the experimental data. The comparisons show that the present gas-kinetic numerical algorithm using the mesoscopic Boltzmann simplified velocity distribution function equation can effectively simulate and reveal the gas flows in microchannels. The numerical experience indicates that this method may be a powerful tool in the numerical simulation of micro-scale gas flows from MEMS.

关键词： Boltzmann model equation, discrete velocity ordinate method, finite-difference scheme, Couette flow, Poiseuille flow, gas flow in short-microchannel.

RRM:An incentive reputation model for promoting good behaviors in distributed systems

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Science in china(Series F) 2008年第11期51卷 1871-1882页

作者： zhang Hong1,2.DUAN HaiXin1,3 & LIU Wu1,3 1 Tsinghua National Laboratory for Information Science and Technology,Tsinghua University,beijing 100084,{2. 2.department of Computer Science and Technology,Tsinghua University,beijing 100084,{2. 3 Network Research Center,Tsinghua University,beijing 100084,{2. 1. Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China 2. department of Computer Science and Technology Tsinghua University Beijing 100084 China 3. Network Research Center Tsinghua University Beijing 100084 China

Reputation systems represent soft security mechanisms that complement traditional information security mechanisms. They are now widely used in online e-commerce markets and communities in order to stimulate good behaviors as well as to restrain adverse behaviors. This paper analyzes the limitations of the conversational reputation models and proposes an incentive reputation model called the resilient reputation model （RRM） for the distributed reputation systems. The objective of this reputation model is not only to encourage the users to provide good services and, therefore, to maximize the probability of good transaction outcomes, but also to punish those adverse users who are trying to manipulate the application systems. The simulation results indicate that the proposed reputation model （RRM） could effectively resist against the common adverse behaviors, while protecting the profits of sincere users from being blemished by those adversaries.

关键词： reputation model distributed system trust soft security

A multiphase mesostructure mechanics approach to the study of the fracture-damage behavior of concrete

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Science china(Technological sciences) 2008年第S2期51卷 8-24页

作者： TANG XinWei1,zhang ChuHan1 & SHI JianJun2.1 State Key Laboratory of Hydroscience and Engineering,Tsinghua University,{2.,{2. 2.department of Urban Construction,Nanhua University,Hengyang 42.001,{2. 1. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China 2. department of Urban Construction Nanhua University Hengyang 421001 China

A multiphase mesostructure mechanical model is proposed to study the deformation and failure process of concrete considering its heterogeneity at the meso scopic ***,concrete is taken as a type of three-component composite material composed of mortar matrix,aggregates and interfaces on the ***,an efficient approach to the disposition of aggregates of concrete and a state matrix method to generate mesh coordinates for aggregates are ***,based on the nonlinear continuum damage mechanics,a meso-scale finite element model is presented with damage softening stress-strain relationship for describing the mechanical behavior of different components of *** this method,heterogeneities of each component in the concrete are considered by assuming the material properties of three components conform to the Weibull distribution ***,based on this multiphase meso-mechanics model,a simulation analysis of fracture behavior of a rock-fill concrete(RFC) beam is *** study includes experimental tests for determining basic mechanical parameters of three components of RFC and four-point flexural beam tests for verification of the *** is preliminarily shown that the numerical model is applicable to studying failure mechanisms and process of concrete type material.

关键词： concrete multiphase mesostructure mechanics numerical simulation experimental research

The role of aerial algae in the formation of the landscape of the Yunnan Stone Forest,Yunnan Province, china

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Science china Earth sciences 2004年第9期47卷 846-864页

作者： TIAN Youping1,3, zhang Jie2. SONG Linhua1 & BAO Haosheng2.1. Institute of Geographic {2. and Natural Resources Research, Chinese Academy of {2., beijing 100101, china 2. department of Geography, Nanjing University, Nanjing 2.0093, china 3. School of Earth {2. and Resources, china University of Geo{2., beijing 100083, china Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China department of Geography Nanjing University Nanjing 210093 China School of Earth sciences and Resources China University of Geosciences Beijing 100083 China

Aerial algae on the surface of carbonate rocks at the Stone Forest, Shilin County, Yunnan Province, china, and their bioerosion were investigated in the field and studied in the laboratory in detail. Through the observation, identification and statistics of more than one hun- dred algal samples and rock samples with the optical microscopes (stereomicroscope, biological microscope) and the scanning electronic microscope (SEM), the relationships between erosional forms on the surface of the Stone Forest and algae and/or algal communities and the genetic mechanism for the formation of erosional forms were analyzed. It is suggested that aerial algae play an active role in bioerosive processes that may affect the formation of karst erosional forms. These effects include both direct and indirect ones. The direct effect is the initiative control (algal shape-controlling role) of algae on the formation of karst forms of various scales, mostly mi- cro-scale (10-3m) and minor-scale (10-3-10-1m) erosional forms. The algal shape-controlling roles can be divided into the algal individual shape-controlling role and the algal community shape-controlling role. The former mostly controls the formation of micro-scale erosional forms, while the latter mostly controls the formation of micro-scale and smaller minor-scale erosional forms. The indirect effect refers to the promoting role of algae in the formation of karst forms, which may affect the formation of karst forms of all types and scales. The bioerosion of algae accelerates the weathering process of the whole Stone Forest karst landforms.

关键词： aerial algae, bioerosion, the Stone Forest, Yunnan Province, china.

Implementation of a multiple round quantum dense coding using nuclear magnetic resonance

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Science china(Physics,Mechanics & Astronomy) 2005年第6期48卷 706-715页

作者： zhang Jingfu1, XIE Jingyi2. WANG Chuan1, DENG Zhiwei3, LU Zhiheng4, & LONG Guilu1,5 1. Key Laboratory For Quantum Information and Measurements of MOE, department of Physics, Tsinghua University, {2.,china 2. department of Materials Science and Engineering, beijing Normal University, beijing 100875, china 3. Testing and Analytical Center, beijing Normal University, beijing 100875,china 4. department of Physics, beijing Normal University, beijing 100875, china 5. Key Laboratory For atomic and Molecular Nanosciences, Tsinghua University, {2.,china 1. Key Laboratory For Quantum Information and Measurements of MOE Department of Physics Tsinghua University 100084 Beijing China 2. department of Materials science and Engineering Beijing Normal University 100875 Beijing China 3. Testing and Analytical Center Beijing Normal University 100875 Beijing China 4. department of Physics Beijing Normal University 100875 Beijing China 5. Key Laboratory For Atomic and Molecular Nanosciences Tsinghua University 100084 Beijing China

A multiple round quantum dense coding scheme based on the quantum phase estimation algorithm is proposed and implemented in a three qubit nuclear magnetic resonance (NMR) quantum computer. Using an m + 1 qubit system, Bob can transmit one of 2.+1 messages to Alice, through manipulating only one qubit and exchanging it between Alice and Bob for m rounds. The information capacity is enhanced to m + 1 bits as compared to m bits in a classical scheme. The scheme has been demonstrated in NMR system, and the experimental results show a good agreement between theory and experiment.

关键词： quantum dense coding, multiple round, nuclear magnetic resorance

A note on n-edge chromatic number

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Chinese Science Bulletin 1997年第23期42卷 1952-1954页

作者： SUN Liang and zhang Zhongfu1. department of Applied Mathematics, {2. Institute of Technology, {2. 100081, china 2. Institute of Applied Mathematics, Lanzhou Institute of Railway, Lanzhou 730070, china department of Applied Mathematics Beijing Institute of Technology Beijing 100081 China

ALL graphs appearing in this note are simple. A graph with p vertices and q edges will becalled a (p, q )-graph. The maximum degree of G is denoted by Δ(G).Let n≥2.be an integer. The n-edge chromatic number X_n (G) of a simple graph G is theminimum cardinality of a set of colors with which one can assign the colors to the edges of Gsuch that the edges on a path of length less than or equal to n receive different *** aim of this note is to explore the bounds for X’_n (G) and X’_n (G) + X’_n (G). It is

关键词： graph complement n-edge chromatic number.