求块-Toeplitz矩阵QR分解中R及R~(￣T)的快速算法

对块数为ｍ×ｎ阶数为ｍｒ×ｎｓ的块－Ｔｏｅｐｌｉｔｚ矩阵Ｔ提出一种通过Ｔ的Ｃｈｏｌｅｓｋｙ因于Ｒ来求Ｔ的ＱＲ分解中上三角矩阵Ｒ及Ｒ－Ｔ的快速算法，计算量为Ｏ（ｍｎｒｓ２）。     

块H—矩阵的进一步推广

对Ｎａｂｂｅｎ提出的块Ｈ－矩阵做进一步推广，使得非对角块矩阵不必是Ｈｅｒｍｉｔｅ矩阵，但仍保留其基本特征不变。对块Ｈ－矩阵提出块Ｈ－分裂及块相容Ｈ－分裂。证明了矩阵的任意块相容Ｈ－分裂都是收敛分裂。     

通过纯有理运算确定矩阵的Jordan块结构

本文讨论如何通过有限步有理运算求得给定矩阵的Jordan块结构(JBS),因为有理运算可以通过符号计算精确实现.与此对照,迄今为止用数值计算求矩阵的JBS与理论结果相距甚远.证明是构造性的,分两大部分:1)确定矩阵A的不变因子,2)根据A的不变因子确定初等因子结构.为求得A的不变因子,我们提出一种新的Las Vegas算法.它是一种概率型算法,这种算法允许失败,但是当且仅当求得正确答案时才停止运算;     

部分性水泡状胎块及流产绒毛水泡样变性临床与病理鉴别

分析部分性水泡状胎块（简称胎块）72例及流产绒毛水样变性（简称变性）31例。结果：平均发病年龄胎块（31．14）早于变性（34．47）；胎块的子宫大于停经月份（9／27），变性的子宫无大于停经月份，子宫排空后HCG水平回复至正常平均时间，胎块为12．99d，变性为5．56d。病理所见：以水肿绒毛占全部绒毛1／3为准，胎块超过1／3的有57例（57／72），变性的3例均为1／3；胎块均有中央池，变性则均无中央池；胎块7例有港湾，90％有扇形绒毛为其病理特征。     

Intermittency of Target Fragments in ^16O-AgBr Collisions at 4.5 A GeV/c

We report the angular distributions of grey and black particles produced in ^16O-AgBr interactions at 4.5 A GeV/c in nuclear emulsion. Intermittency and fractal behaviour are studied for emission spectra of target associated grey and black particles. Intermittent behaviour is observed for both grey and black particles. In both the cases, anomalous dimensions are seen to increase linearly with the order of moments, thereby indicating the association of multifractility with production mechanism of both grey and black particles.     

两个具有群逆的矩阵之和的群逆

在某些条件下给出了非零群逆矩阵A,B的和A+B的群逆存在的充要条件及其表征,一些相关的结果也给出.     

加权网络结构分析

网络研究已经成为机器学习领域中的热点问题之一,近年来发展起来的随机块模型是通过建模生成网络的一种方法．本文对随机块模型加以推广,建立加权的随机块模型,在求解过程中,采用一种可以广泛的用于求解混合模型的变分EM算法．最后通过数据模拟,证明了此方法的可行性．     

3-Blocks with Abelian defect groups isomorphic to Z_{3^m } \times Z_{3^n }

Let G be a finite group and let p be a fixed prime number. Let B be a p-block of G with defect group D. In this paper, we give results on 3-blocks with abelian defect groups isomorphic to Z3m ×Z3n. We are particularly interested in the number of irreducible ordinary characters and the number of irreducible Brauer characters in the block. We calculate two important block invariants k（B） and l（B） in this case.     

截锥形弹穿甲单加筋板的破坏特性

为准确掌握截锥形弹体垂直穿透单加筋板后的打击深度,需要清楚知道弹体穿甲加筋板后的剩余速度.截锥形弹正穿甲板架,形成与截锥面相同的凿块,面板产生花瓣形破坏,腹板受到锥面的挤压发生塑性变形,翼板发生翻转,在此破坏模型基础上,确定板架的能量消耗方式.穿甲过程中,板架耗能主要通过凿块的剪切变形、凿块的动能、板架的挤压塑性变形、...     

Almost self-centered graphs

The center of a graph is the set of vertices with minimum eccentricity. Graphs in which all vertices are central are called self-centered graphs. In this paper almost self-centered (ASC) graphs are introduced as the graphs with exactly two non-central vertices. The block structure of these graphs is described and constructions for generating such graphs are proposed. Embeddings of arbitrary graphs into ASC graphs are studied. In particular it is shown that any graph can be embedded into an ASC graph of prescribed radius. Embeddings into ASC graphs of radius two are studied in more detail. ASC index of a graph G is introduced as the smallest number of vertices needed to add to G such that G is an induced subgraph of an ASC graph.