检索结果-南通市图书馆

Science china Mathematics 2010年第10期53卷 2679-2696页

作者： YANG JiMing1,& CHEN YanPing2 1College of Science,Hunan Institute of Engineering,Xiangtan 411104,china 2school of mathematical sciences,south china normal university,guangzhou 510631,china College of Science Hunan Institute of Engineering school of mathematical sciences South China Normal University

A kind of compressible miscible displacement problems which include molecular diffusion and dispersion in porous media are investigated.A symmetric interior penalty discontinuous Galerkin (SIPG) method is applied to the coupled system of flow and *** the induction hypotheses instead of the cut-off operator and the interpolation projection properties,a priori hp error estimates are *** error bounds in L2(H1) norm for concentration and in L∞(L2) norm for velocity are optimal in h and suboptimal in p with a loss of power 1/2.

关键词： a priori error discontinuous Galerkin compressible miscible displacement coupled system

Estimates on Bloch constants for planar harmonic mappings

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2009年第1期52卷 87-93页

作者： LIU MingSheng school of mathematical sciences, south china normal university, guangzhou 510631, china school of mathematical sciences South China Normal University Guangzhou China

The Bloch constants for quasiregular harmonic mappings and open planar harmonic mappings are considered. Better estimates are obtained. The results, presented in this paper, improve the one made by Chen et al. and Gri... 详细信息

关键词： Bloch constant quasiregular harmonic mapping open planar harmonic mapping 30C99 30C62

THE REGULARITY OF THE FREE BOUNDARY FOR STRIKE RESET OPTION

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2010年第5期30卷 1721-1729页

作者：杨舟 school of mathematical sciences South China Normal University

A strike reset option is an option that allows its holder to reset the strike price to the prevailing underlying asset price at a moment chosen by the holder. The pricing model of the option can be formulated as a parabolic variational inequality and the optimal reset strategy is the free boundary. The smoothness of the free boundary in some cases was showed in our article published in JDE. We would prove its smoothness in the other case in this paper by a generalized comparison principle for the variational inequality.

关键词： strike reset option free boundary variational inequality the comparison principle

A note on periodic solutions for semi-ratio-dependent predator-prey systems

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2010年第1期25卷 1-8页

作者： LIU Xiu-xiang school of mathematical sciences, south china normal university, Guangdong 510631, china school of mathematical sciences South China Normal University Guangdong China

This note investigates the existence of periodic solutions for semi-ratio-dependent predator-prey models with functional response. New sharp criteria without any other nontrivial assumptions are presented by the invariance property of homotopy and analysis technique, which improve and extend many previous work. Some interesting numerical examples are given to illustrate our results.

关键词： Periodic solutions predator-prey system functional response.

A note for preconditioning nonsymmetric matrices

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2010年第1期25卷 93-100页

作者： CHEN Xiao-shan LI Wen school of Mathematics, south china normal university, guangzhou 510631, china school of Mathematics South China Normal University Guangzhou China

In this paper, we consider preconditioners for generalized saddle point systems with a nonsymmetric coefficient matrix. A constraint preconditioner for this systems is constructed, and some spectral properties of the ... 详细信息

关键词： Preconditioner saddle point matrix minimal polynomial Schilder's factorization.

Power functions with low uniformity on odd characteristic finite fields

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第8期53卷 1931-1940页

作者： ZHA ZhengBang 1,3 & WANG XueLi 2 1 school of mathematical sciences,Luoyang normal university,Luoyang 471022,china 2 school of mathematical sciences,south china normal university,guangzhou 510631,china 3 State Key Laboratory of Information Security,Graduate university of Chinese Academy of sciences,Beijing 100049,china school of mathematical sciences Luoyang Normal University school of mathematical sciences South China Normal University State Key Laboratory of Information Security Graduate University of Chinese Academy of Sciences

In this paper,we give some new low differential uniformity of some power functions defined on finite fields with odd *** corollaries of the uniformity,we obtain two families of almost perfect nonlinear functions in GF... 详细信息

关键词： almost perfect nonlinear function differential uniform function finite field

Combined perturbation bounds:Ⅱ.Polar decompositions

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2007年第9期50卷 1339-1346页

作者： Wen LI~(1+) Wei-wei SUN~2 1 school of mathematical sciences,south china normal university,guangzhou 510631,china 2 Department of Mathematics,City university of Hong Kong,Hong Kong,china school of mathematical sciences South China Normal University Guangzhou China Department of Mathematics City University of Hong Kong Hong Kong China

In this paper,we study the perturbation bounds for the polar decomposition A=QH where Q is unitary and H is *** optimal (asymptotic) bounds obtained in previous works for the unitary factor,the Hermitian factor and singular values of A areσ_r^2||ΔQ||_F^2≤||ΔA||_F^2, 1/2||ΔH||_F^2≤||ΔA||_F^2 and ||Δ∑||_F^2≤||ΔA||_F^2,respectively,where∑=diag(σ_1,σ_2,...,σ_r,0,...,0) is the singular value matrix of A andσ_r denotes the smallest nonzero singular *** we present some new combined (asymptotic) perturbation boundsσ_r^2||ΔQ||_F^2+1/2||ΔH||_F^2≤||ΔA||_F^2 andσ_r^2||ΔQ||_F^2+||Δ∑||_F^2≤||ΔA||_F^2 which are optimal for each *** corresponding absolute perturbation bounds are also given.

关键词： polar decomposition perturbation singular value

VORTEX DYNAMICS OF THE ANISOTROPIC GINZBURG-LANDAU EQUATION

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2010年第3期30卷 949-962页

作者：温焕尧丁时进 school of mathematical sciences South China Normal University

In this article, using coordinate transformation and Gronwall inequality, we study the vortex motion law of the anisotropic Cinzburg-Landau equation in a smooth bounded domain Ω （R^2,that is ,Эtuε=j,k=1∑2（ajkЭxkuε）xj＋ε^2^-b（x）（1-｜uε｜^2）uε,x∈Ω,and conclude that each vortex,bj（t）（j=1,2,…,N）satisfies dt^-dbj（t）=-（a（bj（t））^-a1k（bj（t））Эxka（bj（t））,a（aj（t））^-a2k（bj（t））Эxka（bj（t）））,where a（x）=√a11a22-a12^2. We prove that all the vortices are pinned together to the critical points of a（x）. Furthermore, we prove that these critical points can not be the maximum points.

关键词： Anisotropic Ginzburg-Landau equation Gronwall inequality vortex dynamics

Hereditary C~*-subalgebras and comparison of positive elements

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第6期53卷 1565-1570页

作者： WEI ChangGuo1,& WANG LiGuang2 1school of mathematical sciences,Ocean university of china,Qingdao 266071,china 2school of mathematical sciences,Qufu normal university,Qufu 273165,china school of mathematical sciences Ocean University of China school of mathematical sciences Qufu Normal University

Characterizations of hereditary subalgebras generated by subsets of a C*-algebra are given through open *** these results,we give some equivalent conditions of comparison of positive elements.

关键词： hereditary subalgebra open projection positive element

Optical pulse compression using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2004年第1期47卷 33-50页

作者： CAO Wenhua & LIU Songhaoschool of Information, Wuyi university, Jiangmen 529020, china school for Information and Optoelectronic Science and Engineering, south china normal university, guangzhou 510631, china school of Information Wuyi University school for Information and Optoelectronic Science and Engineering South China Normal University

A novel scheme to compress optical pulses is proposed and demonstrated numerically, which is based on a nonlinear optical loop mirror constructed from dispersion decreasing fiber (DDF). We show that, in contrast to the conventional soliton-effect pulse compression in which compressed pulses are always accompanied by pedestals and frequency chirps owning to nonlinear effects, the proposed scheme can completely suppress pulse pedestals and frequency chirps. Unlike the adiabatic compression technique in which DDF length must increase exponentially with input pulsewidth, the proposed scheme does not require adiabatic condition and therefore can be used to compress long pulses by using reasonable fiber lengths. For input pulses with peak powers higher than a threshold value, the compressed pulses can propagate like fundamental solitons. Furthermore, the scheme is fairly insensitive to small variations in the loop length and is more robust to higher-order nonlinear effects and initial frequency chirps than the adiabatic compression technique.

关键词： dispersion decreasing fiber (DDF), optical pulse compression, optical solitons.