二阶非线性摄动微分方程的振动性定理

讨论了二阶非线性摄动微分方程（ａ（ｔ）ｘ’（ｔ）’＋ｐ（ｔ）ｘ’（ｔ）＋Ｑ（ｔ,ｘ（ｔ））＝Ｒ（ｔ,ｘ（ｔ）,ｘ’（ｔ））（１）的解的振动性质。应用分析方法,建立了方程（１）的三个新的振动性定理。     

具周期系数的奇阶中立型微分方程的振动与非振动结果

对于奇阶中立型方程［ｘ（ｔ） － ｐｘ（ｔ－ τ）］（ｎ） ＋ ｑ（ｔ）ｘ（ｔ－ σ） ＝ ０,其中ｑ（ｔ） 为τ－周期函数,分别得出了振动与非振动结果,并将所得结果用到方程［ｘ（ｔ） － Ｐ（ｔ）ｘ（ｔ－ τ）］（ｎ） ＋Ｑ（ｔ）ｘ（ｔ－ σ） ＝ ０,其中Ｑ（ｔ） 为渐近周期函数．     

中立型方程x(t)+cx(t-ㄒ)+ax(t)+bx(t-ㄒ)=0零解渐近稳定的代数判据

本文建立了方程ｘ（ｔ）＋ｃｔ（ｔ－ｔ）＋ａｘ（ｔ）＋ｂｘ（ｔ－ｔ）＝０零解渐近稳定的充要条件,给出了其零解渐近稳定的代数判据,同时纠正了文［２］中出现的错误．     

一类高维时滞微分方程的周期解

本文考虑高维时滞微分方程ｘ′（ｔ）＝Ａ（ｔ,ｘ（ｔ））ｘ（ｔ）＋ｆ（ｔ,ｘ（ｔ－ｒ（ｔ）））其中（ｔ,ｘ）∈Ｒ^ｎ,Ａ（ｔ,ｘ）是ｎ×ｎ连续矩阵,ｆ（ｔ,ｘ）是ｎ维连续向量,ｒ（ｔ）是时间依赖的滞量,应用不动点定理,在确定的条件下,证明了该系统的周期解的存在性与唯一性     

Clifforrd分析中广义双正则函数的(线性)非线性边值问题

本文研究Ｃｌｉｆｏｒｄ分析中广义双正则函数的一个非线性边值问题：Ａ（ｔ１，ｔ２）Ｗ＋＋（ｔ１，ｔ２）＋Ｂ（ｔ１，ｔ２）Ｗ＋－（ｔ１，ｔ２）＋Ｃ（ｔ１，ｔ２）Ｗ－＋（ｔ１，ｔ２）＋Ｄ（ｔ１，ｔ２）Ｗ－－（ｔ１，ｔ２）＝ｇ（ｔ１，ｔ２）ｆｔ１，ｔ２，Ｗ＋＋（ｔ１，ｔ２），Ｗ＋－（ｔ１，ｔ２），Ｗ－＋（ｔ１，ｔ２），Ｗ－－（ｔ１，ｔ２）［］．先讨论解的积分表示式，再研究几个奇异算子，最后用Ｓｃｈａｕｄｅｒ不动点原理（压缩映射定理）证明了解的存在性（唯一性）．目前还没有见到其它国内外学者研究广义双正则函数的非线性边值问题．本文推广了Ｆ．Ｂｒａｃｋｓ，Ｗ．Ｐｉｎｃｋｅｔ［１０］，ＬｅＨｕａｎｇ Ｓｏｎ［１１］，Ｒ．Ｐ．ＧｉｌｂｅｒｔａｎｄＪ．Ｌ．Ｂｕｃｈｎａｎ［１５］和黄沙［１３］的工作     

Mathe matica软件快速上手指南(6)——参数与隐函数方程图形

1　基本二维参数方程作图Ｍａｔｈｍｅｔｉｃａ还能方便地画出参数形式表示的平面图形 ,使用的操作命令是 :ＰａｒａｍｅｔｒｉｃＰｌｏｔ .它的使用格式也有两种 :ＰａｒａｍｅｔｒｉｃＰｌｏｔ[{ｘ(ｔ) ,ｙ(ｔ) },{ｔ ,下限 ,上限 },可选项 ]ＰａｒａｍｅｔｒｉｃＰｌｏｔ[{ｘ1(ｔ) ,ｙ1(ｔ) },{ｘ2 (ｔ) ,ｙ2 (ｔ) },{ｘ3(ｔ) ,ｙ3 (ｔ) },… ,{ｘｎ(ｔ) ,ｙｎ(ｔ) },{ｔ ,下限 ,上限 },可选项 ]其中ｔ可以是一个变量 ,ｘ(ｔ) ,ｙ(ｔ) ,ｘｉ(ｔ) ,ｙｉ(ｔ)等是包含ｔ的表达式 ,它们的意义在解析几何中是很清楚的 ,第一个形式用于作一个函…     

Hopfield型时滞神经网络的指数稳定性

研究了Ｈｏｐｆｉｅｌｄ型随机时滞神经网络ｄｘ（ｔ）＝［－Ａｘ（ｔ）＋Ｂσ（ｘ（ｔ一τ））］ｄｔ＋ｆ（ｔ．ｘ（ｔ）,Ｘ（ｔ—τ））ｄｗ（ｔ）的均方指数稳定性与几乎必然指数稳定性．应用Ｌａｙａｐｕｎｏｖ函数与鞅不等式,建立了这种随机时滞神经网络指数稳定的时滞相关的充分条件．文献中某些关于确定性的时滞神经网络ｘ（ｔ）＝－Ａｘ（ｔ）＋Ｂσ（ｘ（ｔ－τ））与神经网络ｘ（ｔ）＝－Ａｘ（ｔ）＋Ｂσ（ｘ（ｔ））的稳定准则是文中的特殊情况．     

Global Asymptotic Stability for a Class of Nonlinear Populations Model

Ｉｎａｎａｇｅｓｔｒｕｃｔｕｒｅｄｐｏｐｕｌａｔｉｏｎｍｏｄｅｌ,ｔｈｅｆｉｓｈｅｓｓｙｓｔｅｍｏｆａｆｉｓｈｇｒｏｕｎｄｃａｎｂｅｄｅｓｃｒｉｂｅｄａｓｆｏｌｌｏｗｉｎｇｍｏｄｅｌ：ｕ（ａ,ｔ）ｔ＋ｕ（ａ,ｔ）ａ＝－μ（ａ）ｕ（ａ,ｔ）,　０ａＡ,ｔ０,ｕ（ａ,０）＝ｕ０（ａ）,ｕ（０,ｔ）＝ｆ［Ｅ（ｔ）］Ｅ（ｔ）,Ｅ（ｔ）＝∫Ａ０ｂ（ａ）ｕ（ａ,ｔ）ｄａ．（１）Ｗｈｅｒｅｕ（ａ,ｔ）ｄｅｎｏｔｅｓａｇｅｄｉｓｔｒｉｂｕｔｉｖｅｄｅｎｓｉｔｙｆｕｎｃｔｉｏｎｏｆｆｉｓｈｅｄａｔｔ…     

一阶线性时滞微分不等式

研究了一阶线性时滞微分不等式ｘ‘（ｔ）＋ｐ（ｔ）ｘ（τ（ｔ））≤０正解的不存在性,其中ｐ（ｔ）τ（ｔ）∈Ｃ（〔ｔ０,∞）,〔０,∞））,τ（ｔ）≤ｔ所获充分条件改进了许多熟知的结论。     

变系数一阶中立型微分方程的振动性

考虑了微分方程［ｘ（ｔ）－ｐｘ（ｔ－τ）］′＋∑ｎｉ＝１Ｑｉ（ｔ）ｘ（ｔ－τｉ）＝０ｔ≥ｔ０（１）其Ｐ∈Ｒ＋＝［０,∞）,τ,τｉ为正常数,Ｑｉ（ｔ）∈Ｃ（［ｔ０,∞）,Ｒ＋）（ｉ＝１,２,…,ｎ）且∑ｎｉ＝１∫∞ｔ０Ｑｉ（ｔ）ｄｔ＝∞,获得了方程（１）振动的几个充分条件;减弱了文［１］Ｑ（ｔ）为周期系数的条件,推广和改进了文［１］的相应结果,并且有一些结果是新的     

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.     

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.     

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.     

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     

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     

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).     

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.     

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.