A counterexample theorem in quasiconformal mapping theory

Given a quasisymmetric homeomorphismh of the unit circle onto itself, denote byK _n ^* ,H _h andK _h the extremal maximal dilatation, boundary dilatation and maximal dilatation ofh, respectively. It is proved that there exists a family of quasisymmetric homeomorphismsh such thatK _h <H _h =K _h ^* This gives a negative answer to a problem asked independently by Wu and Yang. Furthermore, some related topics are also discussed.     

一个断语的推广及应用

将一个断语进行推广,并借助它介绍一类问题的通用解法.     

Constructions of partitioned difference families

Partitioned difference families (PDFs) arise from constructions of optimum constant composition codes. In this paper, a number of infinite classes of PDFs are constructed, based on known cyclotomic difference families in GF(q). A general approach which obtains PDFs from difference packings and coverings in abelian group is also presented.     

Continuous orbit transitions in a one-dimensional inelastic particle system

Continuous transitions between different periodic orbits in a one-dimensional inelastic particle system with two particles are investigated. We explain why continuous transitions that occur when adding or subtracting a single collision are, generically, of co-dimension 2. However, we show that there are an infinite set of degenerate transitions of co-dimension 1. We provide an analysis that gives a simple criteria to classify which transitions are degenerated purely from the discrete set of collisions that occur in the orbits.     

相关带干扰风险模型的破产概率

本文引进了含相关类带干扰经典风险过程, 研究类之间的相关性对破产概率的影响, 主要研究类之间的相关性对其Lundberg指数的大小关系的影响.     

A variational problem with impurity set

A novel variational problem is investigated which comes from the study of the Ginzburg-Landau model of superconductivity with impurity inclusion. The feature of this variational problem is that it depends on the impurity set. Some properties of the variational problem are established and an application is given to the Ginzburg-Landau model of superconductivity with impurity inclusion.     

On the dynamical reduction of the Vlasov equation

The elimination of a fast-time scale from the Vlasov equation by Lie-transform methods is an important step in deriving a reduced Vlasov equation such as the drift-kinetic Vlasov equation or the gyrokinetic Vlasov equation. It is shown here that this dynamical reduction also leads to the introduction of polarization and magnetization effects in the reduced Maxwell equations, which ensure that the reduced Vlasov–Maxwell equations possess an exact energy–momentum conservation law.     

严格端点与多面体形赋范空间

本文研究了凸α-体的切锥,切流形及切空间与凸α-体的Minkowski泛函的次微分之间的关系.对于凸α-体的每个代数边界点,存在一个拟直和分解使按代数意义该边界点既是一个子空间的光滑点又是拟余子空间的严格端点.所获一般结论可有效地用于多面体形赋范空间理论.     

关于有限群不可约特征标零点的一点注记

在这篇文章中,我们分类了每一个非线性不可约特征标的零点集最多由$3$个共轭类组成的有限亚交换群的结构.