Beurling-Ahlfors延拓与调和映照

研究BA延拓和调和映照的关系.首先,给出了BA延拓为双曲调和的一个必要条件,特别地,若边界对应h局部是C2和奇的,则其BA延拓不是双曲调和的.其次,证明了若h是分段C2的则其BA延拓不是π调和的,除非h(x)=ax+b,x∈R.     

单位圆到凸区域上的调和拟共形映照

设F（x）=p（x）e^ir（x）为单位圆周到约当凸曲线Γ上的保向同胚映照.本文证明:若ess inf|F’（x）|>0且对于一切的φ∈R有|F（φ+x）+F（φ-x）-2F（φ）|≤M|x|^α,这里α>1,M为正常数,则ω=P[F]（z）为单位圆到凸区域Ω=int（Γ）上为调和拟共形映照.     

上半平面到其自身的调和同胚

得到了实轴R上的保向同胚φ(x)在Beurling-Ahlfors延拓下是调和拟共形的充要条件.利用poisson积分具体给出了一个φ(x)延拓成上半平面到其自身的调和同胚.并且给出了这个调和同胚为拟共形的一个充分条件,得到了它的伸张估计.所得结果推广了Michalski的相关结果.     

单位圆盘上的调和拟共形同胚

证明并利用单位圆盘到自身上拟共形映照的一个偏差定理,得到一个判别单位圆盘到自身上调和同胚为调和拟共形同胚的充要条件.作为应用,给出一个判别单位圆盘到自身上调和同胚为调和拟共形同胚的简单判别法.     

单叶调和映照的反函数

设是在一个单连通区域上的单叶调和映照，我们证明了反函数ｚ＝ｆ－１（）也是调和映照的充要条件是ｆ为下面三类函数之一：（ｉ）单叶共形映照；（ｉｉ）仿射交换映照；（ｉｉｉ）具有形式ｆ（ｚ）＝Ａ［ａｚ＋β＋ｌｏｇ（１－ｅ－ａｚ－β）－ｌｏｇ（１－ｅ－ａｚ－β）］＋Ｂ的调和映照，其中Ａ，Ｂ，α和β是常数且满足条件Ｒ（ａｚ＋β）＞０，Ｚ∈Ｄ．     

调和映照的双Lipschitz性质

设w(z)为单位圆盘U到约当区域Ω?C上的调和映照.给出w(z)具有Lipschitz性质的等价条件.进一步地,若Ω为有界凸区域,对其边界函数给出一个较弱的条件,使得w=P[f](z)为调和拟共形映照.     

Hermitian调和映照的Schwarz引理

由Jost和Yau引进的Hermitian调和映照是Riemannian流形上通常的调和映照在Hermitian流形上的一种自然的类比.本文证明了复分析中经典的Schwarz引理对一大类Hermitian调和映照仍然成立.作为推论,我们得到了半共形Hermitian调和映照的Liouville性质.     

平面调和映照的凸半径

首先对K-拟正则调和映照的系数进行估计,进而估计其凸半径;其次,研究系数满足一定条件的调和映照,并给出其相应的精确的凸半径估计.     

恒等映照与调和映照

本文对同一底流形配以不同的度量，然后用讨论该流形上恒等映照以及它与Gauss映照复合的调和性同全测地性的方法，对一些熟知的几何概念，如相对调和映照、相对仿射映照、常曲率流形中具常平均曲率的超曲面、Euclid空间中具常Gauss－Kronecker曲率的超曲面等，给出了用调和映照语言表出的新的分析意义．     

广义Beurling-Ahlfors定理

建立了具有可积球伸张H(z,f)的,上半平面到自身的ID-同胚w=f(z)的Beurling-Ahlfors定理,研究了广义Beurling-Ahlfors扩张的等距问题.     

A note on harmonic quasiconformal mappings

In this note we show that a harmonic quasiconformal mapping f=u+iv with respect to the Poincaré metric of the upper half plane onto itself such that v(x,y)=v(y) or u(x,y)=u(x) is a conformal mapping.     

A Schwarz-Pick inequality for harmonic quasiconformal mappings and its applications

The main result of this paper is the sharp generalized Schwarz-Pick inequality for euclidean harmonic quasiconformal mappings with convex ranges, which generalizes a result given by Mateljevi?. As its applications, we obtain the property of quasi-isometry with respect to the Poincaré distance and an analogue of the Koebe theorem for this class of mappings.     

调和典则实映照

本文从几何函数论的观点研究了一类复值调和典则实函数，在某些假定之下形成了类Ｔ＿Ｈ和它的子类Ｔ￣０＿Ｈ，并给出了Ｔ＿Ｈ和Ｔ￣０＿Ｈ的闭凸壳ＨＴ＿Ｈ和ＨＴ￣０＿Ｈ文中证明了Ｔ＿Ｈ是正规的，Ｔ￣０＿Ｈ是紧的。Ｔ￣０＿Ｈ与ＨＴ￣０＿Ｈ中的函数可用积分公式表示。     

Harmonic mappings onto stars

A general version of the Radó-Kneser-Choquet theorem implies that a piecewise constant sense-preserving mapping of the unit circle onto the vertices of a convex polygon extends to a univalent harmonic mapping of the unit disk onto the polygonal domain. This paper discusses similarly generated harmonic mappings of the disk onto nonconvex polygonal regions in the shape of regular stars. Calculation of the Blaschke product dilatation allows a determination of the exact range of parameters that produce univalent mappings.     

Hölder continuity of quasiconformal harmonic mappings from the unit ball to a spatial domain with C1 boundary

We prove that every quasiconformal mapping from the harmonic -Bloch space between the unit ball and a spatial domain with boundary is globally -Hölder continuous for , with the Hölder coefficient that does not depend neither on the mapping nor on . An analogous result also holds for Lipschitz continuous, quasiconformal harmonic mappings for . This is an approach towards the extension of some results from the complex plane obtained by Warschawski (1951) for conformal mappings and Kalaj (2022) for quasiconformal harmonic mappings.     

A Family of Meromophic Harmonic Mappings

In this article we examine harmonic mappings defined on the punctured unit disk in the spirit of Clunie and Sheil-Small [J. Clunie and T. Sheil-Small (1984 Clunie, J. and Sheil-Small, T. 1984. Harmonic univalent functions. Ann. Acad. Sci. Fenn. Series A. I. Math., 9: 3–25. [Crossref] , [Google Scholar]). Harmonic univalent functions. Ann. Acad. Sci. Fenn. Series A. I. Math., 9, 3–25] and Hengartner and Schober [W. Hengartner and G. Schober (1987 Hengartner, W. and Schober, G. 1987. Univalent harmonic functions. Trans. Amer. Math. Soc., 299: 1–31. [Crossref], [Web of Science ®] , [Google Scholar]). Univalent harmonic functions. Trans. Amer. Math. Soc., 299, 1–31]. We develop a family of mappings such that the members possess finitely many terms in their power series form. Moreover, there is a close coefficient relation between the analytic and co-analytic parts to guarantee the mappings are sense-preserving. After developing the family, we examine conditions for which mappings from the family are sense-preserving, typically real, and univalent, calling this family UTF. In closing, an example of the coefficient region for the sub-class of degree four UTF is included.     

单叶调和映射的线性极值问题

利用线性极值问题有解的必要条件，研究了从单位圆盘到自身的单叶调和映射的傅立叶系数，得到其确界估计。     

单叶调和映射

由于在极小曲面理论中的作用，对调和映射的研究已有较长时间。１９８４年以来，经典解析单叶映射的理论被推广至调和单叶映射，并获得许多结论。这些工作引起人们对它的浓厚兴趣。该文介绍这一课题某些重要成果的概貌，并指出一些尚未解决的问题。它共分六个部分：映射定理；单叶调和函数的数值估计；特殊映射；变分方法；境界性质和在极小曲面中的应用。