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A theoretical model of turbulent fiber suspension and its application to the channel flow

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Science china.Physics,Mechanics & Astronomy) 2010年第9期53卷 1659-1670页

作者： LIN JianZhong1,2 & SHEN SuHua1 1 department of Mechanics,Zhejiang university,hangzhou 310027,china.2 china.Jiliang university,hangzhou 310018,china 1. department of Mechanics Zhejiang University Hangzhou 310027 China2. China Jiliang University Hangzhou 310018 China

A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of *** order to close the above equations,the equation of probability distribution function for mean fiber orientation is also *** theoretical model is applied to the turbulent channel flow and the corresponding equations are solved *** numerical results are verified by comparisons with the experimental *** effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are *** on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

关键词： theoretical model turbulent fiber suspension numerical simulation channel flow modification of velocity profile

A REMARK ON THE UNIQUENESS OF THE HARMONIC MAPS

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Chinese Annals of mathematics,Series B 1991年第3期12卷 301-305页

作者：边保军 department of mathematics Zhejiang university Hangzhou Zhejiang China.

This paper studies the uniqueness of the harmonic maps from Rn into Sn-1. At first it is proved that the map ψ（x）=x|x|:Bn→Sn-1 is the unique energy minimizing harmonic map. Then the uniqueness of the harmonic maps... 详细信息

关键词： minimizing harmonic uniqueness neighborhood 时功胜日三价一斋七印 verify

A NOTE ON THE STABILITY OF A CLASS OF DEGENERATE PLANAR CRITICAL POINTS

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Journal of Systems Science & Complexity 2007年第3期20卷 461-469页

作者： Tusen HUANG Qi ZHANG Institute of mathematics Zhejiang Sci-Tech University Hangzhou 310018 China. department of mathematics Nanjing University Nanjing 210093 China.

A computable expression of the asymptotic expansion of the return map for a degenerate singular point of a class of planar differential system is given, and hence the stability and the type of the singular point can b... 详细信息

关键词： Isolated singular point monodromy singular point characteristic direction return map stability.

Simple proofs of the Bedrosian equality for the Hilbert transform

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Science china.mathematics 2009年第3期52卷 507-510页

作者： WANG SiLei department of mathematics, Zhejiang university, hangzhou 310027, china department of mathematics Zhejiang University Hangzhou 310027 China

Two simple proofs of Bedrosian theorem are given.

关键词： Hilbert transform Bedrosian theorem filter 42B20 42B25

Convergence on the iteration of Halley family in weak conditions

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Chinese Science Bulletin 1997年第7期42卷 552-555页

作者： WANG Xinghuadepartment of mathematics, hangzhou university, hangzhou 310028, china department of mathematics Hangzhou University Hangzhou China

WE have obtained the convergence theorems of the iteration of Halley family by the point estimate of Smale. In the point estimate, map f which is desired to be solved is presumed to be analytic in some proper neighbor... 详细信息

关键词： operator equations Banuch space the iteration of Halley family convergence weak conditions.

Inverse minimum spanning tree problem and reverse shortest-path problem with discrete values

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Progress in Natural Science:Materials International 2006年第6期16卷 649-655页

作者： LIU Longcheng and HE Yong (department of mathematics, Zhejiang university, hangzhou 310027, china.State Key Laboratory of CAD & CG, Zhejiang university, hangzhou 310027, china. [a]department of mathematics Zhejiang University Hangzhou China [b]State Key Laboratory of CAD & CG Zhejiang University Hangzhou China

In this paper, we consider two network improvement problems with given discrete values: the inverse minimum spanning tree problem and the reverse shortest-path problem, where the decrements of the weight of the edges are given discrete values. First, for the three models of the inverse minimum spanning tree problem (the sum-type, the bottleneck-type and the constrained bottleneck-type), we present their respective strongly polynomial algorithms. Then, we show that the reverse shortest-path problem is strongly NP-complete.

关键词： minimum spanning tree shortest-path problem inverse problem reverse problem computational complexity.

An invariance principle for negatively associated random variables

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Chinese Science Bulletin 1997年第5期42卷 359-364页

作者： LIN Zhengyandepartment of mathematics and Information Science, hangzhou university, hangzhou 310028, china department of mathematics and Information Science Hangzhou University Hangzhou China

A finite collection of random variables, X1,…, Xn （n≥2）, is said to be negatively associated （NA） if any two coordinatewise nondecreasing （or nonincreasing） functions f1 and f2 on Rn, such that （?）j=fj（X1,…,Xn） have a finite variance for j=1, 2 and Cov（（?）1,（?）2）≤0; an infinite collection is said to be NA if every finite subcollection is NA. It is relative to a lot of practical problems, such as reliability theory, percolation models and multivariate statistical analysis. Matula （1992） studied the strong laws of large numbers for an NA sequence. Recent-

关键词： negatively associated random variables weak invariance principle.

Rotationally symmetric translating soliton of H^k-flow

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Science china.mathematics 2010年第4期53卷 1011-1016页

作者： SHENG WeiMin & WU Chao department of mathematics,Zhejiang university,hangzhou 310027,china 1. department of mathematics Zhejiang University Hangzhou 310027 China

This paper mainly considers the translating soliton of H k-flow for k > *** give the asymptotic expression of the entire rotationally symmetric translating soliton,and obtain non-convex 'Wing-like' solution as well as... 详细信息

关键词： H k-flow translating soliton 'Wing-like' solution

Shape blending of artistic brushstroke represented by disk B-spline curves

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Progress in Natural Science:Materials International 2007年第12期17卷 1501-1507页

作者： Cheng Min1,2 and Wang Guojin1(1. department of mathematics, Zhejiang university, hangzhou 310027, china.2. department of mathematics, Zhejiang university of Technology, hangzhou 310032, china. department of mathematics Zhejiang University Hangzhou 310027 China 2. department of mathematics Zhejiang University of Technology Hangzhou 310032 China

This paper presents an algorithm for automatically generating in-between frames of two artistic brushstrokes. The basic idea of the algorithm is to represent the two key frames of artistic brushstrokes in disk B-spline curves, and then make blending of their geometric intrinsic variables. Given two key frames of artistic brushstrokes, the skeleton curves can be obtained by certain skeleton-based techniques. After disk B-spline representation of the key frames is generated, interpolation of the intrinsic variables of the initial and the target disk B-spline curves is carried out. Examples show that this method can efficiently create in-between frames of artistic brushstrokes.

关键词： computer aided calligraphy shape blending brushstroke disk B-spline curve skeleton.