非奇H-矩阵的实用性新判定

给出了非奇H矩阵几个新的实用性判据,改进了近期的一些结果,并给出相应数值例子来说明结果的有效性.     

非广义对角占优矩阵的判定准则

给出了判定非广义对角占优矩阵的充要条件,从理论上彻底解决了不可约非广义对角占优矩阵的判定问题,并给出了判定不可约非广义对角占优矩阵的具体算法.     

广义对角占优矩阵的判定准则

In this paper,some new sufficient conditions for generalized dominant matrices are given,and some results in [1] are generalized and improved.     

局部双对角占优矩阵的注记

1引言非奇异H矩阵是计算数学、数学物理、控制论等领域中具有广泛应用的重要矩阵类,研究其充分条件自然引起人们的兴趣．文[1]中定义了一类局部双对角占优矩阵,并由此得到了非奇异H矩阵的判别方法．我们指出,文[1]所获充分条件中所给出的四个不等式条件,其中第四个不等式条件可蕴涵其余三个,进而定义了另一类局部双对角占优矩阵,并由此获得了非奇异H矩阵新的判别方法．设A=(a_(ij))∈C~(n×n),R_i(A)=sum from j≠i|a_(ij)|,i∈N={1,2,…,n}．若|a_(ii)|≥R_i(A),(?)i∈N,则称A为对角占优矩阵,记为A∈D_o;若不等式中每个不等号都是严格的,则称A为     

Rounding Errors in Solving Block Hessenberg Systems

A rounding error analysis is presented for a divide-and-conquer algorithm to solve linear systems with block Hessenberg matrices. Conditions are derived under which the algorithm computes a stable solution. The algorithm is shown to be stable for block diagonally dominant matrices and for M-matrices.

     

Admission control of multi-class traffic with service priorities in high-speed networks

We consider a fluid model of a system that handles multiple classes of traffic. The delay and cell-loss requirements of the different classes of traffic are generally widely different and are achieved by assigning different buffers for different classes, and serving them in a strict priority order. We use results from the effective bandwidth of the output processes (see Chang and Thomas (1995)) to derive simple and asymptotically exact call-admission policies for such a system to guarantee the cell-loss requirements for the different classes assuming that each source produces a single class traffic. We compare the admission-control policies developed here with the approximate policy studied by Elwalid and Mitra (1995) for the case of two-class traffic. This revised version was published online in June 2006 with corrections to the Cover Date.     

A remark on generalised Putnam-Fuglede theorems

Given , the algebra of operators on a Hilbert space , define and by and . Let and be two classes of operators strictly larger than the class of normal operators. Define (resp., if (resp., for all and . This note shows that the equivalence holds for a number of the commonly considered classes of operators.

     

具非零元素链二重几何平均对角占优矩阵

本文引进了具非零元素链二重几何平均对角占优矩阵的概念,讨论了它的性质及其与具非零元素链对角占优矩阵,非奇Ｈ－矩阵等的关系     

ℓ<Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>-Diagonally Dominant Symmetric Operators

The existence of _p-universal diagonally dominant symmetric liner operators on separable Hilbert spaces is discussed. Also, properties of these operators and their characterization in terms of their spectra are investigated.     

On the Electric Field Lines of the Dominant Mode in Millimetric V-Groove Guide by Finite Element Method

In this paper, the electric field lines of the dominant mode in a closed V-groove guide as well as an open one are analysed by finite element method. The results show that the electric field lines are not parallel to the parallel plate region, but perpendicular to them. Since the attenuation increase with increasing frequency when the electric field lines are perpendicular to the mental walls, the V-groove is not suitable to be used in millimeter and submillimeter wavebands, and it is can't be regarded as low-loss wave guiding structures.