△^2u=λu＋N＋4／N—4＋μf（x）的多解存在性

讨论了非齐次双调和方程边值问题｛△＾２ｕ＝λｕ＋Ｎ＋４／ｕＮ－４＋ｕｆ（ｘ）,ｘ∈Ωｎ＝△ｕ｜ｎ＝０,的两个正解的存在性和非存在性,这里Ω是Ｒ＾Ｎ内有界光滑区域,Ｎ〉４,λ∈Ｒ＾１,μΠ０,ｆ（ｘ）是非负连续函数。     

二维带形无界区域中Navier—Stokes方程整体吸引子及其维数估计

该文讨论二维无界带形区域中Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程（Ⅰ）｛ｕｔ－△ｕ＋ｕｉэｕэｘｉ＝－△ｐ＋ｆ（ｘ，ｔ）∈Ω×Ｒ＋（１）ｄｉｖｕ＝０（２）ｕ（Ｘ，ｔ）∈（Ｈ＾１０（Ω）ｆｏｒ ｔ〉０（３）ｕ（ｘ，０）＝ｕ０（ｘ）∈Ｈ（４）其中Ω＝（０，ｄ）×Ｒ，ｄ〉０为一常数，ｕ与ｐ为未知量，其中ｕ＝（ｕ１，ｕ２）为速度场，ｐ表示压力。我们证明了当ｕ０∈Ｈ，ｆ∈Ｖ且ｆ「ｌｏｇ（ｅ＋│ｘ│＾２）」＾１２∈Ｌ     

环形域上半线性椭圆型方程径向正解的多重性

讨论如下的半线性方程：｛－△ｕ＝ｇ（│ｘ│）ｆ（ｕ） ｉｎΩ ｕ＝０ ｏｎδΩ这里Ω＝｛ｘ∈Ｒ＾Ｎ：Ｒ〈│ｘ│〈Ｒ｝ Ｎ≥２，０〈Ｒ〈Ｒ〈＋∞，在适当的条件下，运用变分方法我们得到了该方程存在两个非平凡径向正解。     

关于Fujita型反应扩散方程组的Cauchy问题

本文研究Ｆｕｊｉｔａ型反应扩散方程组ｕｔ－Δｕ＝α１｜ｕ｜ｑ１－１ｕ＋β１｜ｖ｜ｐ１－１ｖ，（ｘ∈ＲＮ，ｔ＞０），ｖｔ－Δｖ＝α２｜ｕ｜ｑ２－１ｕ＋β２｜ｖ｜ｐ２－１ｖ，ｕ（ｘ，０）＝ｕ０（ｘ）０，ｖ（ｘ，０）＝ｖ０（ｘ）０，（ｘ∈ＲＮ）Ｌｐ解的整体存在性和有限时间Ｂｌｏｗ ｕｐ问题．这里ｑｉ＞１，ｐｉ＞１（ｉ＝１，２），α１０，α２＞０，β１＞０，β２０，１ｐ＋∞．     

关于含非凸约束的变化问题

本文分别讨论泛函Ｉｐ（ｕ）＝∫Ω｛「α＾αβ（ｘ，ｕ）ｇｉｊ（ｘ，ｕ）Ｄαｕ＾ｉＤβｕ＾ｉＤβｕ＾ｊ」＾ｐ／２＋Ｐ（ｘ，ｕ）｝ｄｘ，在一般的非凸几何约束Ｆ１＝｛ｕ∈Ｈ＾１，ｐ（Ω，Ｒ＾Ｎ）；ｕ∈Ｍａ．ｅ．于Ω，ｕ│δΩ＝ｕ０｝和非凸图约束下的极小化问题，其中Ｍ为Ｒ＾Ｎ中的任一光滑开子集或Ｒ＾Ｎ的一个开子流形。     

具临界指数和临界非线性边界条件的拟线性椭圆型方程Neumann问题

本文给出ＲＮ（Ｎ３）中有界光滑区域Ω上的拟线性椭圆型方程：－∑Ｎｉ＝１ｘｉ·｜Ｄｕ｜ｐ－２ｕｘｉ＝λ｜ｕ｜ｐ－２ｕ＋ａ（ｘ）｜ｕ｜ｐ－２ｕ＋ｆ（ｘ，ｕ），ｘ∈Ω（λ＞０，ｐ＝Ｎｐ／（Ｎ－ｐ），２ｐ＜Ｎ）在边界条件：－｜Ｄｕ｜ｐ－２Ｄνｕ｜Ω＝ψ（ｘ）｜ｕ｜ｑ－２ｕ（ｑ＝（Ｎ－１）ｐ／（Ｎ－ｐ））下的多解性结果．     

Fujita型反应扩散方程组整体解的存在性、非存在性与渐近性质

本文研究 Ｆｕｊｉｔａ型反应扩散方程组的初值问题：ｕｔ－△ｕ＝ａ１ｕ~α１－１ｕ＋ｂ１ｖ~β１－１ｖ,ｖｔ－△ｖ＝ａ２ｕ~α２－１ｕ＋ｂ２ｖ~β２－１ｖ,ｕ（Ｘ,０）＝ｕ０（Ｘ）,Ｖ（Ｘ,０）＝Ｖ０（Ｘ）,（Ｘ,ｔ）Ｒ~Ｎ ｘ Ｒ~＋,其中 ａｉ,ｂｉ≥ ０, αｉ,βｉ≥ １（ｉ＝ １,２）,给出了非负整体 Ｌ~ｐ解与古典解存在性与非存在性的一系列充分条件,并讨论了解的渐近性质．本文所用方法和所得结果与已有的工作［１－４］,有很大的不同,不但在某些方面推广了［１－５］,而且从某些方面改进了［１］的结果。     

非线性抛物型方程的爆破

本文考虑非线性抛物型方程ｕｔ＝ｅ＾ｕ（△ｕ＋ｕ），ｘ∈Ω，证明在Ω上当－△ｕ＝λｕ的第一特征值λ１（Ω）〈１时，解ｕ有有限时刻爆破。     

非线性波动与社会传播混合型方程的整体紧吸引子

本文研究非一波动与神经传播混合型方程ｕｔｔ＝ｕｘｘｔ＋σ（ｕｘ）ｘ－ｈ（ｕ）ｕｔ－ｆ（ｕ）＋ｇ（ｘ）初边值问题的整体吸引子，在σ∈Ｃ＾２，σ（ｓ）〉σ０〉０及ｈ（ｓ）∈Ｃ＾１，－Ｃｏ〈ｈ（ｓ）（０〈Ｃｏ〈λ１／２）且∫ｏ＾ｕｈ（ｓ）ｓｄｓ〈Ｃｕ＾２条件下我们得到了与该方程相应的动力系统整体紧吸引子的存在性，并证明了它具有有限的Ｈａｕｓｄｏｒｆｆｘ维数和ｆｒａｃｔａｌ维数。     

一个反应扩散过程的门槛结果

本文讨论反应扩散方程Ｃａｕｃｈｙ问题（ｕｔ－△ｕ＝ｕ＾ｐ－ｕ＾ｐ－ｕ，Ｘ∈Ｒ＾ｎ，ｔ∈（０，Ｔ），ｕ（ｘ，０）＝ｕ０（ｘ）≥０，Ｘ∈Ｒ＾ｎ，解的整体存在性，渐近性质和Ｂｌｏｗ－ｕｐ问题，其中１＜ｑ＜ｐ＜ｎ＋２／ｎ－２，ｎ≥３或者１＜ｑ＜ｐ＋∞，ｎ＝２．得到门槛结果。     

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.