人口问题中广义三维GINZBURG-LANDAU模型方程

本文讨论三维广义Ginzburg-Landau模型方程的初边值问题ut=-a1↓△^4u a2↓△^2u ↓△^2g(u) G(u),σu/σv=0,σ△u/σv=0,u(x,0)=u0(x)解的整体存在性、唯一性、渐近性质和爆破。     

Multiple positive solutions for a fourth-order p-Laplacian Sturm-Liouville boundary value problems on time scales

In this paper, we investigate the existence of multiple positive solutions for the following fourthorder p-Laplacian Sturm-Liouville boundary value problems on time scales ﹛[φp(u△△(t))u △△= f(t, u(σ(t))), t ∈ [a, b],α0 u(a)- β0u△(a) = 0, γ0 u(σ(b)) + δ0 u△(σ(b)) = 0,α0(φp(u△△))(a)- β0(φp(u△△))△(a) = 0,γ0(φp(u△△))(σ(b)) + δ0(φp(u△△))△(σ(b)) = 0,where φp(s) is the p-Laplacian operator. Under growth conditions on the nonlinearity f some existence results of at least two and three positive solutions for the above problem are obtained by virtue of fixed point theorems on cone. In particular, the nonlinearity f may be both sublinear and superlinear.     

Darcy-Stokes方程的一种局部稳定化有限元方法

1 引 言 {σu-v△u+▽p=f在Ω ▽·u=0在Ω (u)=0在(e)Ω 其中u=(u1,u2)为二维向量,Ω(c)R2是多边形区域,σ,v是粘性系数(σ,V不能同时为零),f表示外力.     

一类非线性抛物方程粘性解的存在惟一性及其在图像处理中的应用

证明一类非线性抛物方程ut-g(DGσ*u,D2Gσ*u)Du div DDuu=0u(x,0)=u0粘性解的存在惟一性,并通过实验验证了该模型在图像处理中的应用.     

含临界指数的拟线性椭圆系统正对称解的存在性（英文）

本文讨论一类拟线性椭圆型系统-Δpu=μ|u|p-2 u|x|p+2αQ(x)(α+β)|x|s|u|α-2 u|v|β+σ1|u|q1-2 u,x∈Ω,-Δpv=μ|v|p-2v|x|p+2βQ(x)(α+β)|x|s|u|α|v|β-2v+σ2|v|q2-2v,x∈Ω,u=v=0,x∈Ω,其中Δpu=div(|▽u|p-2▽u)是p-Laplacian,2≤pN,ΩRN是一个有界光滑区域,0∈Ω,且Ω关于O(N)的一个闭子群G对称,0≤μ,=((N-p)/p)p,σ1,σ2≥0,0≤sp,α,β1满足α+β=p*(s)=(N-s)p/(N-p),pq1,q2p*=Np/(N-p),Q(x)是Ω上的连续G对称函数.应用Palais对称临界原理和变分方法,我们建立了该系统几个全新的正G-对称解的存在性结果.     

关于一个渗流问题解的局部性质

设Ω是u维空间R~n中的有界区域,T>0.σ(u)为R~1上的局部Lipschitz函数,满足σ(u)∈C~1(0,∞)并且当u≤0时σ(u)=0,当u>0时σ’(u)>0.考虑方程     

奇异半线性反应扩散方程组Cauchy问题

本文讨论如下问题其中{(б)u/(б)t-(1/tσ)△u=αvp1+β1vp1+f1(x),t>0,x∈RN,(б)u/(б)t-(1/tσ)△v=α2uq2+β2vp2+f2(x),t>0,∈RN,limt→0+u(t,x)=limt→0+v(t,x)=0,x∈Rn,其中σ＞0,pi＞1,qi＞1(i=1,2),α1≥0,α2＞0,β1＞0,β2≥0,fi(x)(i=1,2)连续有界非负,(f1(x),f2(x))(≡／)(0,0).给出了非负局部解存在的几个充分条件和解的爆破结果.     

Critical Exponent for the Parabolic Equation u_t=Δu~m + h(t)u~p in a Cone

In this paper,we study the initial-boundary value problem of porous medium equation ut = Δum + h(t)up in a cone D =(0,∞) ×Ω,where h(t) ～ tσ.Let ω1 denote the smallest Dirichlet eigenvalue for the Laplace-Beltrami operator on Ω and let l denote the positive root of l 2 +(n 2)l = ω1.We prove that if m p ≤ m + 2(σ+1) n+l + σ(m 1),then the problem has no global nonnegative solutions for any nonnegative u0 unless u0 = 0;if p m + 2(σ+1) n+l + σ(m1),then the problem has global solutions for some u 0 ≥ 0.     

双重退化抛物型方程整体解的存在性和L~∞估计

文考虑双重退化抛物型方程ut=div(|u|r|u|m--2u)+A(u)带有零边界条件的初边值问题的整体解存在性,唯一性和解在t=0,∞处的L∞模估计.证明了当u0∈Lq(Ω)时,整体解u(t)满足估计‖u(t)‖∞≤C(1+t-λβ)(1+t)-β/M,‖(u(t)|r/(m-1)u(t))‖m≤C(1+t-μ)(1+t)-σ,t＞0,这里λ,μ,σ,M,β为依赖于m,q,N和r的适当正常数.     

时标上动力方程在右局部边值条件下正解的存在性

主要研究时标上二阶动力学方程u~(△△)(t)+λ_p(t)f(t,u(σ(t)))=0在右局部边值条件u(0)=0=u~△(σ(1))下正解的存在性.应用格林函数和锥上Krasnoselskii不动点原理给出其正解存在的充分条件及正解存在的特征值区间.     

RECENT PROGRESS ON SPHERICAL HARMONIC APPROXIMATION MADE BY BNU RESEARCH GROUP ——In memory of Professor Sun Yongsheng

As early as in 1990, Professor Sun Yongsheng, suggested his students at Beijing Normal University to consider research problems on the unit sphere. Under his guidance and encouragement his students started the research on spherical harmonic analysis and approximation. In this paper, we incompletely introduce the main achievements in this area obtained by our group and relative researchers during recent 5 years （2001-2005）. The main topics are： convergence of Cesaro summability, a.e. and strong summability of Fourier-Laplace series; smoothness and K-functionals; Kolmogorov and linear widths.     

A unified approach to certain problems of best local approximation

In this paper we study best local quasi-rational approximation and best local approximation from finite dimensional subspaces of vectorial functions of several variables. Our approach extends and unifies several problems concerning best local multi-point approximation in different norms.     

Boundedness for commutators of multipliers on Hardy type spaces

In this paper, we study the commutators generalized by multipliers and a BMO function. Under some assumptions, we establish its boundedness properties from certain atomic Hardy space Hb^p（R^n） into the Lebesgue space L^p with p 〈 1.     

THE 8~(th) INTERNATIONAL CONGRESS ON INDUSTRIAL AND APPLIED MATHEMATICS

<正>August 10-14,2015Beijing,ChinaThe International Congress on Industrial and Applied Mathematics(ICIAM)is the premier international congress in the field of applied mathematics held every four years under the auspices of the International Council for Industrial and Applied Mathematics.From August 10 to 14,2015,mathematicians,scientists     

Towards Excellence in Science Chinese Academy of Sciences

<正>May 26,2014,Beijing Science is a human enterprise in the pursuit of knowledge.The scientific revolution that occurred in the 17th Century initiated the advances of modern science.The scientific knowledge system created by     

Bounds for the zeros of polynomials

Let P(z)=∑↓j=0↑n ajx^j be a polynomial of degree n. In this paper we prove a more general result which interalia improves upon the bounds of a class of polynomials. We also prove a result which includes some extensions and generalizations of Enestrǒm-Kakeya theorem.     

Boundedness of commutators related to Marcinkiewicz integrals on hardy type spaces

In this paper, the authors study the boundedness of the operator [μΩ, b], the commutator generated by a function b ∈ Lipβ(Rn)(0 ＜β≤ 1) and the Marcinkiewicz integrals μΩ, on the classical Hardy spaces and the Herz-type Hardy spaces in the case Ω∈ Lipα(Sn-1)(0 ＜α≤ 1).     

Jacobi polynomials used to invert the laplace transform

Given the Laplace transform F(s) of a function f(t), we develop a new algorithm to find an approximation to f(t) by the use of the classical Jacobi polynomials. The main contribution of our work is the development of a new and very effective method to determine the coefficients in the finite series expansion that approximation f(t) in terms of Jacobi polynomials. Some numerical examples are illustrated.     

Generalization of the interaction between Haar approximation and polynomial operators to higher order methods

In applications it is useful to compute the local average empirical statistics on u. A very simple relation exists when of a function f（u） of an input u from the local averages are given by a Haar approximation. The question is to know if it holds for higher order approximation methods. To do so, it is necessary to use approximate product operators defined over linear approximation spaces. These products are characterized by a Strang and Fix like condition. An explicit construction of these product operators is exhibited for piecewise polynomial functions, using Hermite interpolation. The averaging relation which holds for the Haar approximation is then recovered when the product is defined by a two point Hermite interpolation.