Constructions of optimal difference systems of sets

Difference systems of sets (DSSs) are combinatorial configurations which were introduced in 1971 by Levenstein for the construction of codes for synchronization. In this paper, we present two kinds of constructions of difference systems of sets by using disjoint difference families and a special type of difference sets, respectively. As a consequence, new infinite classes of optimal DSSs are obtained.     

复合材料弹性常数测定的超声波技术

本文简要地回顾了利用超声波脉冲技术测定复合材料弹性常数的历史,概述了现状、基本原理与基本方法,并对今后的研究方向提出了看法．      

由Schrdinger算子定义的Riesz变换的L~p估计(英文)

本文主要讨论了当非负位势 V(x)属于某逆Holder类时,由一致椭圆算子L=-div(A(x))+V(x)所定义的 Riesz变换在 L~p空间的有界性。     

花旗参中铜含量的光度法测定

研究了铬天青S(CAS)与铜(Ⅱ)的显色体系。在氯化十六烷基吡啶(CPC)存在下,铜与CAS在酸性介质中生成1:5的绿蓝色三元配合物,最大吸收波长622mm,摩尔吸光系数8.8×10~4,铜含量在2～15μg/25mL范围内符合比耳定律。方法灵敏选择性好,用于花旗参中铜含量的测定,结果满意。     

二面体群上Hopf路余代数的结构分类

从Hopf quiver出发,借助于右kZ_u(c)-模的直积范畴■ Mkz_(u(C))与kG-Hopf双模范畴kG/kG M kG/kG之间的同构,当G是二面体群D_3时,给出了Hopf路余代数kQ~c的同构分类及其子Hopf代数kG[kQ_1]结构.     

P_(4k-1)-factorization of bipartite multigraphs

LetλKm,n be a bipartite multigraph with two partite sets having m and n vertices, respectively. A Pν-factorization ofλKm,n is a set of edge-disjoint Pν-factors ofλKm,n which partition the set of edges ofλKm,n. Whenνis an even number, Ushio, Wang and the second author of the paper gave a necessary and sufficient condition for the existence of a Pν-factorization ofλKm,n. When v is an odd number, we proposed a conjecture. However, up to now we only know that the conjecture is true forν= 3. In this paper we will show that the conjecture is true whenν= 4k-1. That is, we shall prove that a necessary and sufficient condition for the existence of a P4k-1-factorization ofλKm,n is (1) (2k-1)m≤2kn, (2) (2k-1)n≤2km, (3)m n = 0 (mod 4k-1), (4)λ(4k-1)mn/[2(2k-1)(m n)] is an integer.     

带有积分条件的泛函微分方程的稳定性分析

本文讨论了下列泛函微分方程: 这里T>0,T_1≥0。令Q=bf(a)/c。若Q≤1,则上述方程有唯一平衡点且全局稳定。若Q>1,则上述方程的正平衡点渐近稳定,另一平衡点不稳定。所采用的证明方法是构成Lyapunov泛函和利用广义持征方程,与[2]、[3]不同.当f(y)=y即可得K.L.cooke[3]的结论.当T=T_1=O,f(y)=y即可得[2]的讨论。     

关于块三角预处理广义鞍点矩阵特征值界的注记

1引言考虑如下2×2阶块线性系统:（?）其中A∈R^n×n对称正定,B∈R^m×n行满秩,C∈R^m×m对称半正定且m≤n.通常A和B是大型稀疏阵.这样的系统常称为广义鞍点问题的线性系统.特别地,若C=0时称为鞍点问题.这类问题广泛来源于许多实际问题,如约束二次优化问题,约束最小二乘问     

二溴羟基苯基荧光酮-AI-F!~--Triton X-100四元显色体系的研究与应用

研究了二溴羟基苯基荧光酮与铝的显色体系.在Triton X-100及F~-存在下,铝与二溴羟基苯基荧光酮在碱性介质中形成1∶2的玫瑰红色的四元配合物,最大吸收波长559nm.摩尔吸光系数1.46×10~5,铝含量在0～5μg/25ml符合比耳定律.方法灵敏,选择性高,用于镁合金中微量铝的直接测定,取得满意结果.     

一个反应扩散方程整体解的存在性

对一个由反应扩散方程推出的抛物型自由边界问题进行了研究,该问题含有参数γ和τ,已证明了当γ充分大时,该问题存在唯一稳定解．现在主要证明γ,τ均充分大时,该问题存在整体解,即当0＜t＜ ∞时,该问题的解存在．