调和映射的可积拟共形延拓

本文研究了平面调和映射的可积拟共形延拓问题.利用经典的共形映射的拟共形延拓方法和调和映射的性质,获得了一些条件使得调和映射可以拟共形延拓至整个平面且其复伸缩商关于双曲度量是p次可积的,推广了解析单叶函数的相关结果.     

平面双线性映射的伸缩率分析

拟共形映射能较好地保持角度,在形状编辑等几何处理领域有着广泛应用.但该类映射不易构造,特别是复杂区域之间的拟共形映射构造,是一个困难且重要的问题.本文研究了一类简单的拟共形映射,即双线性映射,讨论了其伸缩率的分布情况,证明了伸缩率的最大值一定在四边形区域的顶点上取得.相关结论为复杂区域之间拟共形映射的构造提供了良好的理论基础.数值实验验证了结论的正确性.     

具有边界对应的拟共形扩张的伸缩商估计

本文研究了拟共形映射的极值问题.利用Beurling-Ahlfors扩张函数,获得了一类新的拟共形映射,推广了文献[1]的结果.     

关于拟共形映射的基本不等式及其应用

本文建立了平面上拟共形映射的一个基本不等式，构造了拟共形映射的充满圆序列，证明了其Ｂｏｒｅｌ方向的存在性。     

Apollonian度量与Apollonian边界条件

证明了(1)■中真子域D上的Apollonian度量αD是拟共形映射的拟不变量;(2)■中严格一致域是拟共形不变的;(3)■中的Jordan域D是拟圆当且仅当D是严格一致域,作为应用,进一步得到了Apollonian边界条件,拟共形映射和局部Lipschitz映射之间的关系。     

具有不可缩伸缩商的拟共形映射

在研究拟共形映射的唯一极值性时,Reich引入了具有不可缩伸缩商的拟共形映射的概念.本文将继续讨论这类映射,并给出无穷小情形下的一些类似结果     

具有不可缩伸缩商的拟共形映射

在研究拟共形映射的唯一极值性时,Reich引入了具有不可缩伸缩商的拟共形映射的概念.本文将继续讨论这类映射,并给出无穷小情形下的一些类似结果.     

Apollonian度量与Apollonian边界条件

证明了(1)(-R)n中真子域D上的Apollonian度量aD是拟共形映射的拟不变量;(2)(-R)n中严格一致域是拟共形不变的;(3)(-R)2中的Jordan域D是拟圆当且仅当D是严格一致域.作为应用,进一步得到了Apollonian边界条件,拟共形映射和局部Lipschitz映射之间的关系.     

拟圆周的Hausdorff维数

考察了中的闭集的Hausdorff维数在渐近共形映射下的不变性,以及拟圆周的Hausdorff维数和拟共形映射的边界伸缩商的关系,证明了中的闭集的Hausdorff维数在渐近共形映射下是不变的,给出了拟圆周的Hausdorff维数与边界伸缩商的一个不等式的简单证明,在某种意义上推广了相关的两个结果.     

线性测度与K-拟共形调和映射

本文主要讨论调和映射与线性测度之间的关系.首先,证明单位圆周上任意可测集在单叶且保向的调和映射作用下的边界线性测度的最佳偏差定理.其次,建立K-拟共形调和映射的Schwarz型引理,并利用K-拟共形调和映射来刻画M-Lavrentiev域.最后,讨论具有有限径向长度的K-拟共形调和映射的系数估计以及径向长度与曲线周长之间的比值.     

Quasiconformal motions and isomorphisms of continuous families of Möbius groups

In their paper [17], Sullivan and Thurston introduced the notion of quasiconformal motions, and proved an extension theorem for quasiconformal motions over an interval. We prove some new properties of (normalized) quasiconformal motions of a closed set E in the Riemann sphere, over connected Hausdorff spaces. As a spin-off, we strengthen the result of Sullivan and Thurston, and show that if a quasiconformal motion of E over an interval has a certain group-equivariance property, then the extended quasiconformal motion can be chosen to have the same group-equivariance property. Our main theorem proves a result on isomorphisms of continuous families of Möbius groups arising from a group-equivariant quasiconformal motion of E over a path-connected Hausdorff space. Our techniques connect the Teichmüller space of the closed set E with quasiconformal motions of E.     

The limit sets of Schottky quasiconformal groups are uniformly perfect

In this paper we study Schottky quasiconformal groups. We show that the limit sets of Schottky quasiconformal groups are uniformly perfect, and that the limit set of a given discrete non-elementary quasiconformal group has positive Hausdorff dimension.

     

拟共形映照的双曲面积偏差估计

The distortion property of hyperbolic area of planar quasiconformal mappings is studied in this paper.In the case of radial quasiconformal mappings and angular deformed quasiconformal mappings their hyperbolic area distortions are estimated quite sharply.The result can be applied to judge whether the hyperbolic area of a planar subset is explodable.     

Quasiconformality, homeomorphisms between metric measure spaces preserving quasiminimizers, and uniform density property

We characterize quasiconformal mappings as those homeomorphisms between two metric measure spaces of locally bounded geometry that preserve a class of quasiminimizers. We also consider quasiconformal mappings and densities in metric spaces and give a characterization of quasiconformal mappings in terms of the uniform density property introduced by Gehring and Kelly.     

Hausdorff dimension distribution of quasiconformal mappings on the Heisenberg group

We construct quasiconformal mappings on the Heisenberg group which change the Hausdorff dimension of Cantor-type sets in an arbitrary fashion. On the other hand, we give examples of subsets of the Heisenberg group whose Hausdorff dimension cannot be lowered by any quasiconformal mapping. For a general set of a certain Hausdorff dimension we obtain estimates of the Hausdorff dimension of the image set in terms of the magnitude of the quasiconformal distortion.     

On the Douglas–Dirichlet functional and harmonic quasiconformal mappings

In this article, we discuss the minimal mappings of Douglas–Dirichlet functional and harmonic quasiconformal mappings, and solve the uniqueness problem of harmonic quasiconformal mappings posed by Shibata.     

Modular equations and distortion functions

Modular equations occur in number theory, but it is less known that such equations also occur in the study of deformation properties of quasiconformal mappings. The authors study two important plane quasiconformal distortion functions, obtaining monotonicity and convexity properties, and finding sharp bounds for them. Applications are provided that relate to the quasiconformal Schwarz Lemma and to Schottky’s Theorem. These results also yield new bounds for singular values of complete elliptic integrals.      

On the dynamics of a family of entire functions

We prove that for any bounded type irrational number 0θ1,the boundary of the Siegel disk of fα(z)=e2πiθsin(z)+αsin3(z),α∈C,which centered at the origin,is a quasicircle passing through 2,4 or 6 critical points of fαcounted with multiplicity.     

Nehari函数族的偏差定理与拟共形延拓

本文讨论了Nehari函数族的偏差性质,得到了这类函数及其导数的若干偏差定理,同时研究了这类函数的拟共形延拓,并给出拟共形延拓的精确表达式.