不可压缩理想势流绕两平行平板间圆柱流动的新的近似解析解

文献[1]得到了不可压缩理想势流绕两平行平板间圆柱流动的近似分析解.本文指出,用М.Е.Швец法[2]亦可得到与文献[1]完全相同的结果.如果用本文作者新提出的改进了的М.Е.Швец法[2]则可得到比文献[1]更加精确的结果.有算例.     

EI~n代数与*EI~n代数

为了更好地解决模糊概念的表示问题 ,文 [1]、 [2 ]引入了 AFS.代数和 AFS.结构。为了讨论AFS.结构的拓扑性质 ,本文在 [1]、 [2 ]的基础上 ,进一步讨论了 EIn 代数和 * EIn 代数的性质与结构。     

离散事件动态系统的能达能观性与对干扰解耦的周期合并配置

能达与不能达子空间,能观与不能观子空间是 Wonham 教授创建的多变量控制几何方法的几个基本概念.对 DEDS 文献[2,3]提出了分别能达概念及其充要条件;文[2]还给出了与能达有关的标准结构;文[3]提出了上界能观及其充要条件;文[4]给出了用反馈合并周期的充分条件;文[5]得到了用输出反馈合并配置周期的充要条件.在以上文献     

椭球等高分布位移参数的minimax估计与Stein两阶段估计

§1 引言在椭球等高分布族中讨论一些统计量的分布性质及有关统计性质的多元统计分析通常称之为广义多元统计分析.近年来,广义多元统计分析发展非常迅速,它的理论研究一直在进行着,并得到了许多与正态母体类似的结果.要了解这方面的概貌可参见文献[1]、[3]、[4]、[5]、[6]、[10]等.文献[9]对椭球等高分布族理论进行了系统的总结.下面我们介绍一下文     

关于生灭过程的边界问题

<正> 一、引言钟开莱教授在他的文章[1]和[2]中研究了一般马尔科夫链(MC)的边界理论,本文将针对生灭过程研究文[1]和[2]中的一些问题,所用的各种符号与[1]、[2]和[4]基本一致.     

计算WG逆的高斯-约尔当消元法

1引言 近年来,广义逆在工程技术等许多领域中得到了广泛地应用.如控制理论[1],最小二乘问题[2,3],矩阵分解[4],图像处理和统计[5].特别地,{2}-逆在病态问题的稳定逼近[1,6]和线性与非线性问题[7,8]中发挥着重要的作用.在[9]中,Baksalary和Trenkler研究了核逆的相关问题.在[10]中,Manjunatha和Mohana定义了Core-EP逆,在[11]中,Wang和Chen研究和定义了WG逆,并研究了WG逆的相关性质.在[12]中,Chen和Wang提出了一种高阶收敛迭代方法,并将其应用于计算Moore-Penrose逆.在[13]中,Liu,Jin和Yu对这种计算方法进行了推广.     

L_p 空间中的 Korovkin 定理

H.Bohoman 与 P.P.Korovkin 在1959年建立了著名的 Bohoman-Korovkin 定理.1966年 V.K.Dzjadyk 在 L_p[a,b]上给出了类似的定理:定理 A.设 T_n 是 L_p[a,b]到 L_p[a,b]的有界线性正算子.若     

矩阵对角化方法的再探讨

引言文 [1 ]— [3]对矩阵对角化方法的简化问题进行了讨论 ,给出了简便易行的判定和求法 .区别于传统的方法 ,文 [1 ]和 [2 ]把问题归结为矩阵的乘法运算 ,文 [3]则在特殊情形下把问题归结为求特征值与特征向量同步求解 .后者收到了判定和求解一体化的效果 .这种同步操作的思想已在文 [4]和 [5]中见到 ,但均未做到一步成功 .本文对此作进一步探讨 ,一方面改进了 [4]和 [5]的方法 ,使同步求解一步到位 ;另一方面较容易地得到矩阵对角化的十分简单的判定方法 ,以致于判定和求解都是从最终的λ—矩阵中“读”出来的 .其主要依据是以下两个定…     

具有拟离散谱的拓扑传递动力系统

Abramov 在[1]中首先应用 Halmus 和 Neuman 在[2]中所引进的拟特征函数与拟特征值的概念将具有离散谱的各态历经动力系统的理论推广到了一类具有拟离散谱的完全各态历经动力系统上。此后,F.Hahn 与 W.Parry 在[3]中研究了具有拟离散谱的完全极小动力系统.本文讨论的是一类具有拟离散谱的完全拓扑传递动力系统,得到了若干与[3]平行的结果。     

K一致凸空间中的拟非扩张映象

§1 引言 作者在[3]中提出拟非扩张映射的概念,在[3]、[4]中,作者与张广禄证明了在一致凸空间的有界闭凸集及在Banach空间的紧凸集上,拟非扩张自映射有不动点。K一致凸空间是1979年F.Sullivan在[1]中提出的新概念。俞鑫泰、臧尔彬、刘证等在[2]中进行了深入的研究.本文在K一致凸空间中建立了与[3]、[4]中同样的结果。     

Global exponential stability of a class of retarded impulsive differential equations with applications

This paper studies the dynamics of a class of retarded impulsive differential equations (IDE), which generalizes the delayed cellular neural networks (DCNN), delayed bidirectional associative memory (BAM) neural networks and some population growth models. Some sufficient criteria are obtained for the existence and global exponential stability of a unique equilibrium. When the impulsive jumps are absent, our results reduce to its corresponding results for the non-impulsive systems. The approaches are based on Banach’s fixed point theorem, matrix theory and its spectral theory. Due to this method, our results generalize and improve many previous known results such as [3], [5], [6], [9], [17], [18], [23], [32], [38], [43], [51], [52]. Some examples are also included to illustrate the feasibility and effectiveness of the results obtained.     

Graphs with two isomorphism classes of spanning unicyclic subgraphs

The graphs whose spanning unicyclic subgraphs partition into exactly two isomorphism classes are characterized.This work is a continuation of [6] where graphs with one isomorphism class of spanning unicyclic graphs are characterized. The analogous question for spanning trees was posed in [10] and graphs with one isomorphism class of spanning trees were characterized in [2], [3], [4], [7], [11] while graphs with two isomorphism classes of spanning trees were characterized in [4], [5]. Related topics are treated in [1], [8], [9].     

直积的推广与正交函数系的生成

Two new kinds of direct product of matrices are defined. Their properties are investigated . Direct products of matrix and set of continuous functions are also defined. Many complete sets of orthogonal functions, such as those sets given by Walsh [2], Paley [3], Chrestenson[4 ], and Watari [ 5 ], may be generated by : these newkinds of direct product . Direct products are also applicable to the generation of sets of piecewise orthogonal functions .     

亚纯函数微分多项式f~kQ[f]+P[f]的零点分布

文[4]对简单形式的微分多项式fkf’+a的零点分布进行了讨论,文[1]对一般形式的微分多项式fkQ[f]+P[f]的零点分布进行了讨论.但由于极点给证明带来的困难,这些工作主要是对整函数来做的.本文证明了任一满足δ(∞,f)>k+2ΓQ+3ΓP+2/2k+2ΓQ+1的超越亚纯函数f,微分多项式fkQ[f]+P[f]在不含f,Q[f]极点和P[f]零、极点的可数个圆盘并集之外有无穷多个零点,其中k≥3Γp+2,而ΓQ,ΓP分别是f的微分多项式Q[f],P[f]的权.文[1]和[2,4,6]中的结论是本文结论的特殊情况.     

矩阵多项式空间的进一步研究

设A为数域F上的n级矩阵,记F[A]={f(A)|f(x)∈F[x]},它显然是F~(n×n)的子空间.讨论了F[A]的基和维数,引入了f(A)的坐标和F[A]的因式子空间的概念,给出了用因式子空间表示F[A]的几个定理,刻画了F[A]的结构.     

On the Determination of a Density Function by Its Autoconvolution Coefficient

We investigate eigenvalues and eigenvectors of certain linear variational eigenvalue inequalities where the constraints are defined by a convex cone as in [4], [7], [8], [10]-[12], [17]. The eigenvalues of those eigenvalue problems are of interest in connection with bifurcation from the trivial solution of nonlinear variational inequalities. A rather far reaching theory is presented for the case that the cone is given by a finite number of linear inequalities, where an eigensolution corresponds to a (+)-Kuhn-Tucker point of the Rayleigh quotient. Application to an unlaterally supported beam are discussed and numerical results are given.     

Convergence of Directional Methods under mild differentiability and applications

A semilocal convergence analysis for Directional Methods under mild differentiability conditions is provided in this study. Using our idea of recurrent functions, we provide sufficient convergence conditions as well as the corresponding errors bounds. The results are extended to hold in a Hilbert space setting and a favorable comparison is provided with earlier works [6], [7], [8], [9], [10], [11] and [20]. Numerical examples are also provided in this study.     

A class of norms of iterative methods for solving systems of linear equations

A new class of norms which generalize norms previously investigated by Young [9, 14], Sheldon [4, 5], Golub [1], Golub and Varga [2], Varga [6], Wachspress [7], Young and Kincaid [12], Young [14], and Kincaid [3] is introduced. Expressions for these norms applied to the matrices associated with various iterative methods are developed.Work on this paper was sponsored by NSF Grant GP-8442 and Army Grant DA-ARO(D)-31-124-G1050 at The University of Texas at Austin.     

Summation of almost convergent divergent sequences,topological methods

In this paper we give a characterization of the conservative matrices that sum only those divergent sequences which are not almost convergent. Such conditions are similar to those which are necessary and sufficient for a conservative matrix to sum no bounded divergent sequence (Agnew [1], Mazur-Orlicz [4], Wilansky-Zeller [6], and Zeller [7]). There are, however, some differences showing, that the results mentioned above cannot be transmitted without any restriction. Parts of this paper have been already developed by the author more detailed in [5].     

曲线拐点充分条件证明中的常见错误

文[1]给出了判别曲线拐点的两个充分条件,文[2]给出了一个充分条件,但三个定理的证明都是错误的.同时,文[1]的两个推论也是错误的.本文通过反例分析了其错因,并给出了文[1]中一个拐点充分条件的正确证明.