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NEW APPROACH TO THE LIMITER FUNCTIONS

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Journal of Computational Mathematics 1999年第1期17卷 41-58页

作者： Jin Li Ze-min Chen Zi-qiang Zhu(beijing university of{2. and astronautics, beijing 100083, China) beijing Univ Aeronaut & Astronaut Beijing 100083 Peoples R China

In this paper we discuss three topics on the designing of the limiter functions. (1) To guarantee the TVD property (2. To maintain enough artificial viscosity. (3) A method to form TVB limiter which can ensure second ... 详细信息

关键词： finite difference methods TVD schemes limiter function

Fractal Structure of the Core Loss Spectrum of Co-based Amorphous Soft Magnetic Alloy with Constant Permeability

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 54-56页

作者： Yiping Chen (Applied science school,{2. of science and Technology beijing, beijing 100083, China) Applied science school University of Science and Technology Beijing Beijing 100083 China

In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 2.0 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.

关键词： amorphous soft magnetic alloy constant permeability core loss fractal

Molecular structure and biological function of proliferating cell nuclear antigen

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Progress in Natural science:Materials International 2007年第10期17卷 1127-1135页

作者： Song Nanmeng1, Sang Jianli1 and Xu Heng2.1. Institute of Cell Biology, College of Life science, beijing Normal{2., beijing 100875, China 2. Emory{2. school of Medicine, GA 30332. USA) Institute of Cell Biology College of Life Science Beijing Normal University Beijing 100875， China Emory university school of Medicine GA 30332 USA

Proliferating cell nuclear antigen (PCNA) is the core component of replication complex in eukaryote. As a processive factor of DNA polymerase delta, PCNA coordinates the replication process by interacting with various replication proteins. PCNA appears to play an essential role in many cell events, such as DNA damage repair, cell cycle regulation, and apoptosis, through the coordination or organization of different partners. PCNA is an essential factor in cell proliferation, and has clinical significance in tumor research. In this article we review the functional structure of PCNA, which acts as a function switch in different cell events.

关键词： PCNA Function Switch PCNA Binding Motif Cell Cycle DNA Replication DNA Repair.

The effect of diffusion on the permanence of Smith population model in a polluted patch

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Communications in Nonlinear science and Numerical Simulation 2001年第4期6卷 217-221页

作者： Zhuoqin YANG, Qishao LU and Zaizhong YANG school of science,{2., beijing 100083, China Department of Mathematics, Inner Mongolia university, Inner Mongolia 01002., China school of science Beijing Univ. of Aero. and Astronautics Beijing 100083 China Department of Mathematics Inner Mongolia University Inner Mongolia 010021 China

The effect of diffusion on the permanence of population in a polluted patch is studied by setting up a single-population diffusive system in two patches. The analysis focuses on the case that the toxicant input in the polluted patch has a limit value. It is shown that when there is no diffusion and the limit value exceeds a certain value, the population in the polluted patch goes extinct; when the diffusion exists and population diffusive coefficients between the two patches satisfy some conditions, the population of the system goes either permanent or extinct.

关键词： population diffusion system pollution permanence extinction

Calculating model of mass action concentrations for Ag-Au-Cu melts

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Rare Metals 2002年第1期21卷 43-47页

作者： ZHANG Jian Metallurgy school, university of{2. and Technology beijing, beijing 100083, China Metallurgy school University of Science and Technology Beijing 北京 100083

Based on phase diagrams and measured activities, the calculatingmodel of mass action concentrations for het- erogeneous meltsAg-Au-Cu was formulated. Calculated results agree with the improvedresults of recent research work, Showing that the model formulatedcan reflect the structural characteristics of these melts. In thismodel, without the help Of any empirical parameters, only threeequilibrium constants are used, hence it is simple, lear, andfavorable to the sim- Plification of calculation.

关键词： activity mass action concentration eutectic Solid solution

Quasi-Carbon Fibers and the Composites

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Journal of Materials science & Technology 2000年第5期16卷 486-490页

作者： Lulu SONG, Weihong ZHONG+, Zuoguang ZHANG and Zhijie SUN (Department of Materials science & Engineering, beijing university of aeronautics and astronautics,{2. 100083, China) Department of Materials science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The aim of this report is to study the properties of quasi-carbon fibers (QCF) prepared from the PAN fiber precursor by pyrolysis at a temperature between 400℃ and 12.0℃. The resistivity of QCF with different heat-treated temperature (HTT) was investigated by a Hall-35 testing system, and the flexural properties of the result composites (QCFC) are also discussed. In addition, the scanning electronic microscope (SEM) was utilized to observe the surface morphology of QCF and the fracture section of QCFC obtained from flexural testing.

关键词： QCF Quasi-Carbon Fibers and the Composites HTT

Pattern phenomena in an rf discharge dusty plasma system

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science China(Physics,Mechanics & Astronomy) 2006年第5期49卷 588-596页

作者： HUANG Feng1,2. YE Maofu2.& WANG Long2.1. College of science, China Agricultural university,{2. 100083, China 2. Institute of Physics, Chinese Academy of sciences,{2. 100080, China 1. College of science China Agricultural University Beijing 100083 China 2. Institute of Physics Chinese Academy of Sciences Beijing 100080 China

Various dust patterns are observed in an rf discharge dusty plasma system. According to the dust growth process from small to large in size, the formation of different dust patterns can be divided into two stages: the small-particle stage (or dust cloud stage), and the large-particle stage (or dust crystal stage). The evolution relations between different dust patterns with gas pressure changing are investigated. Dust voids, dust acoustic waves and strong turbulence modes are presented at the small-particle stage. The self-organized dust lattices and dust clusters are investigated at the large-particle stage. The static structure of a dust lattice is characterized by means of the pair correlation function. Dust clusters formed by particles with different numbers and the regular evolution of the clusters with gas pressure are also investigated. The packing sequences of dust clusters are verified through two-dimensional confined molecular dynamics simulations.

关键词： dusty plasma dust patterns

A new DNA algorithm to solve graph coloring problem

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Progress in Natural science:Materials International 2007年第6期17卷 733-738页

作者： Jiang Xingpeng1, Li Yin2. Meng Ya3 and Meng Dazhi2.1. National Laboratory of Pattern Recognition,Institute of Automation, Chinese Academy of sciences, beijing 100080, China 2. College of Applied sciences, beijing university of Technology, beijing 10002., China 3. school of science, beijing Institute of Technology, beijing 100081, China) National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Beijing 100080 China College of Applied sciences Beijing University of Technology Beijing 100022 China school of science Beijing Institute of Technology Beijing 100081 China

Using a small quantity of DNA molecules and little experimental time to solve complex problems successfully is a goal of DNA computing. Some NP-hard problems have been solved by DNA computing with lower time complexity than conventional computing. However, this advantage often brings higher space complexity and needs a large number of DNA encoding molecules. One example is graph coloring problem. Current DNA algorithms need exponentially increasing DNA encoding strands with the growing of problem size. Here we propose a new DNA algorithm of graph coloring problem based on the proof of four-color theorem. This algorithm has good properties of needing a relatively small number of operations in polynomial time and needing a small number of DNA encoding molecules (we need only 6R DNA encoding molecules if the number of regions in a graph is R).

关键词： DNA computing NP-hard problem graph coloring problem.

An exploration for the macroscopic physical meaning of entropy

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science China(Technological sciences) 2010年第7期53卷 1809-1816页

作者： WU Jing1 & GUO ZengYuan2.1 College of Energy and Power Engineering, Nanjing university of aeronautics and{2., Nanjing 2.0016, China 2.Key Laboratory for Thermal science and Power Engineering of Ministry of Education, school of Aerospace, Tsinghua university, beijing 100084, China 1. College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education School of Aerospace Tsinghua University Beijing 100084 China

The macroscopic physical meaning of entropy is analyzed based on the exergy (availability) of a combined system (a closed system and its environment), which is the maximum amount of useful work obtainable from the system and the environment as the system is brought into equilibrium with the environment. The process the system experiences can be divided in two sequent sub-processes, the process at constant volume, which represents the heat interaction of the system with the environment, and the adiabatic process, which represents the work interaction of the system with the environment. It is shown that the macroscopic physical meaning of entropy is a measure of the unavailable energy of a closed system for doing useful work through heat interaction. This statement is more precise than those reported in prior literature. The unavailability function of a closed system can be defined as T0S and p0V in volume constant process and adiabatic process, respectively. Their changes, that is, AiTgS) and A (p0V) represent the unusable parts of the internal energy of a closed system for doing useful work in corresponding processes. Finally, the relation between Clausius entropy and Boltzmann entropy is discussed based on the comparison of their expressions for absolute entropy.

关键词： entropy macroscopic physical meaning exergy heat interaction