无穷时滞Liénard方程的周期解(英文)

讨论具有无穷时滞Liénard型方程x+(?²F(x))/(?x²)x+g(t,x_t)=p(t)的周期解问题, 利用重合度理论得到了周期解存在的充分条件.     

有限环上典型群的阶

本文通过“取模”，“取值和”，“取积”等方法，将有单位元的有限环Ｒ上典型群阶的计算转化为有限域上典型群阶的计算，并计算了Ｒ上ｎ－维自由模Ｖ_ｎ（Ｒ）中ｋ－维自由子模的个数．     

具有两个IM公共值集的亚纯函数

本文讨论了亚纯函数的唯一性问题,证明了存在一个具有13个元素的集合S使得对任意两个非常数的亚纯函数f与g,只要满足E(S,f)=E(S,g)和E({∞),f)=E({∞},g),必有f≡g.     

一阶线性时超微分不等式

研究了一阶线性时超微分不等式x'(t)-p(t)x(t r)≥0正解的不存在性,其中p(t)∈C([t_0,∞),[0,∞)),T∈R~ 。     

Bayesian prediction for the two-parameter exponential distribution based on type II doubly censoring

The two-parameter exponential distribution is proposed to be an underlying model, and prediction bounds for future observations are obtained by using Bayesian approach. Prediction intervals are derived for unobserved lifetimes in one-sample prediction and two-sample prediction based on type II doubly censored samples. A numerical example is given to illustrate the procedures, prediction intervals are investigated via Monte Carlo method, and the accuracy of prediction intervals is presented. Supported by the National Natural Science Foundation of China (79970022) and Aviation Fund (02J53079).     

矩阵最小奇异值下界的估计

1．引言与记号记号：儿已（：。X。阶复矩阵集合；从利：A的特征值；一（川：A的最小奇异值；A”：A的共轭转置；【I州：绝对向量范数诱导的矩阵范数；。l（A为A的最大奇异值）时，最小奇异值m（人）下界的估计a是一个关键的数．an（A的下界在其他许多领域中都是一个极重要的课题，因而最小奇异值下界的估计一直是普遍关注的问题二［1，2］等仅利用A的元素得到了N（A）下界的简单估计，至今仍被广泛引用，其结果如下：设AE地（q．若【aiiIZ凡（A）且冲i三q（川，d＝1，…，n，则本文试图通过矩阵的分块和H矩阵特性等来讨论。（）的…     

正负系数的扰动的中立型微分方程的稳定性

In this paper the perturbed neutral differential equation with positive and negative coefficients d/dt[x(t)-C(t)x(t-r)] p(t)x(t-x)-Q(t)x(t-δ)=f(t,x(t)),t≥t0is considered. Sufficient conditions for the zero solution of this equation to be uniformly stable as well as asymptotically stable are obtained.     

同无限二面体群关联的晶体群的分类

设Ｖ是实数域Ｒ｝上的一个２－维向量空间，Ｖ带有一个仿射的或不定的对称双线性型．无限二面体群Ｗ能够被看作ＧＬ（Ｖ）的一个子群．在本文中，在仿射群Ａ（Ｖ）中共轭的意义下将分类同Ｗ关联的所有晶体群．     

环上矩阵的Moore-Penrose逆

本文研究环上矩阵的广义逆,得到其存在的充要条件,给出它的表达式,推广了以往文献的相应结果。     

REMARKS ON CRITERIA OF PREQUASI-INVEX FUNCTIONS

§1　IntroductionConvexity and generalized convexity play a central role in mathematical economics,engineering,managment science,and optimization theory.Therefore,the research onconvexity and generalized convexity is one of the most important aspects in mathematicalprogramming.Recently,[1] derived criteria for quasiconvex functions under lowersemicontinuity and upper semicontinuity conditions.In[2 ] Yang et al introduced variousconceptsof prequasi-invex functions,types ofgeneralized version o…