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Application and Comparison of Two SGS Models in Large Eddy Simulation of FreeTurbulent Jet Flow

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Communications in Nonlinear Science and Numerical Simulation 1999年第1期4卷 12-19页

作者： Hong YAN and Mingde SU (department of Engineering Mechanics, tsinghua university, beijing 100084, china) department of Engineering Mechanics Tsinghua University Beijing 100084 China

Large eddy simulations of spatially evolved turbulent round jets were presented. The two SGS models called the standard Smagorinsky’s eddy viscosity model and the non-eddy viscosity stimulated small scale(SSS) model developed by Shah & Ferziger were applied. The Reynolds number of the flow was taken as 10000 based on the orifice diameter and the axial velocity in the orifice. The comparison between these two models showed that the standard Smagorinsky’s viscosity model with Smagorinsky’s constant of 0.1 underestimated the turbulent intensity, while the SSS model showed a better agreement with the experiment. Also the SSS model was used to investigate the development of vortex. The convective boundary condition at the outflow boundary was adopted to ensure less effect of noise on the upstream.

关键词： stimulated small scale model smagorinsky’s eddy viscosity model Round jet, Large eddy simulation

THE PHYSICAL ENTROPY OF SINGLE CONSERVATION LAWS

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Journal of Computational mathematics 1998年第5期16卷 437-444页

作者： (department of mathematics, Peking university, beijing 100871, china) beijing Univ Dept Math Beijing 100871 Peoples R China

By means of the comparisons with the formulas in statistical mechanics and thermodynamics, in this paper it is demonstrated that for the single conservation law partial derivative(t)u + partial derivative(x)f(u) = 0, if the flux function f(u) is convex (or concave), then, the physical entropy is S = -f(u); Furthermore, if we assume this result can be generalized to any f(u) with two order continuous derivative, from the thermodynamical principle that the local entropy production must be non-negative, one entropy inequality is derived, by which the O.A. Olejnik's famous E- condition can be explained successfully in physics.

关键词： conservation laws entropy entropy production

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 applied 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

On mean curvatures in submanifolds geometry

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Science china mathematics 2008年第6期51卷 1127-1134页

作者： GE JianQuan department of Mathematical Sciences,tsinghua university,beijing 100084,china department of Mathematical Sciences Tsinghua University Beijing 100084 China

By using moving frame theory,first we introduce 2p-th mean curvatures and(2p+1)-th mean curvature vector fields for a *** then give an integral expression of them that characterizes them as mean values of symmetric functions of principle *** we apply it to derive directly the celebrated Weyl-Gray tube formula in terms of integrals of the 2p-th mean curvatures and some Minkowski-type integral formulas.

关键词： moving frame mean curvature tube 53A07 53C42

On fixed-points and singular values of transcendental meromorphic functions

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Science china mathematics 2010年第3期53卷 887-894页

作者： ZHENG JianHua department of Mathematical Sciences, tsinghua university, beijing 100084, china 1. department of Mathematical Sciences Tsinghua University Beijing 100084 China

In this paper we make a further discussion of a relationship between the number of fixed-points and distribution of singular values along the round annuli centered at the origin of a transcendental meromorphic function. To attain our purpose we first establish a fundamental inequality for the modulus of derivative of a holomorphic covering mapping whose image is an annulus by virtue of the hyperbolic metric. The inequality is of independent significance. We make a simple survey on some domain constants for hyperbolic domains.

关键词： meromorphic functions fixed points singular points hyperbolic metric covering mapping

A cross-monotonic cost sharing method for the facility location game with service installation costs

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Science china mathematics 2009年第11期52卷 2530-2536页

作者： XU DaChuan department of applied mathematics,beijing university of Technology,beijing 100124,china 1. department of applied mathematics Beijing University of Technology Beijing 100124 China

In this paper,we consider the metric uncapacitated facility location game with service installation costs. Our main result is an 11-approximate cross-monotonic cost-sharing method under the assumption that the install... 详细信息

关键词： facility location game cross-monotonic cost-sharing method linear programming relaxation 90C27 91A12

An attempt to differential Galois theory of second order polynomial system and solvable subgroup of Mbius transformations

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Science china mathematics 2007年第5期50卷 748-760页

作者： Ke-ying GUAN & Jin-zhi LEI School of Science, beijing Jiaotong university, beijing 100044, china Zhou Pei-Yuan Center for applied mathematics, tsinghua university, beijing 100084, china School of Science Beijing Jiaotong University Beijing 100044 China Zhou Pei-Yuan Center for applied mathematics Tsinghua University Beijing 100084 China

By introducing the conception "relativistic differential Galois group" for the second order polynomial systems, we establish the relation between the conformal relativistic differential Galois group and the subgroup of Mobius transformations, and prove that the system is integrable in the sense of Liouville if its conformal relativistic differential Galois group is solvable with a derived length at most 2. Some omissions on the structures of solvable subgroups of Mobius transformations at the first author’s article published in this journal in 1996 are refreshed in this paper.

关键词： conformed differential Galois group Mobius transformations integrability in the sense of Liouville

L~∞ CONVERGENCE OF TRUNC ELEMENT FOR THE BIHARMONIC EQUATION

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Journal of Computational mathematics 1997年第1期15卷 14-22页

作者： M. Wang(department of mathematics, beijing university, beijing, china) 北京大学数学系北京

The paper considers the L∞ convergence for TRUNC finite elements solving the boundary value problems of the biharmonic equation. The nearly optimal L∞ estimates for the error of first order derivatives are *** TRUNC plate element is proposed and developed by Argyris et al.. The numerical experiences show that the element has very good .***,[1l2]. The mathematicalproof of convergence of the TRUNC element is given by Shi Zong-ci in paper [3]. Thispaper will consider the L~∞ convergence for the TRUNC plate element.

关键词： Biharmonic equations Convergent boundaries Shape functions Vertices Interpolation Weighting functions Integers

Cilia and ciliopathies:From Chlamydomonas and beyond

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Science china(Life Sciences) 2008年第6期51卷 479-486页

作者： PAN JunMin department of Biological Sciences and Biotechnology, tsinghua university, beijing 100084, china 1. department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China

The biological function of motile cilia/flagella has long been recognized. The non-motile primary cilium, once regarded as a vestigial organelle, however, has been found recently to play unexpected roles in mammalian physiology and development. Defects in cilia have profound impact on human health. Diseases related to cilia, collectively called ciliopathies include male infertility, primary cilia dyskinesia, renal cyst formation, blindness, polydactyly, obesity, hypertension, and even mental retardation. Our current understanding of cilia and ciliopathies has been fueled by basic research employing various model organisms including Chlamydomonas, a unicellular green alga. This review article provides a general introduction to the cell biology of cilia and an overview of various cilia-related diseases.

关键词： Chlamydomonas cilia flagellla human disease ciliopathy