平面上具有有界Fréchet导数的调和映照单叶半径的精确估计

给定单位圆盘D={z||z|1}上调和映照f(z)=h(z)+g(z),其中h(z)和g(z)为D上的解析函数,满足f(0)=0,λf(0)=1,ΛfΛ.通过引入复参数λ,|λ|=1,本文研究调和映照Fλ(z)=h(z)+λg(z)和解析函数Gλ(z)=h(z)+λg(z)的性质,得到Fλ(z)和Gλ(z)单叶半径的精确估计.作为应用,本文得到单位圆盘D上某些K-拟正则调和映照Bloch常数的更好估计,改进和推广由Chen等人所得的相应结果.     

一类近于凸调和映照的凸像半径与Pre-Schwarz导数的估计

对任意给定的α∈[0,1),对单位圆盘D上规范化的保向调和映照类H的一个近于凸子类P~0(α)={f=h+g∈H:R{h′(z)-α}|g′(z)|,z∈D,g′(0)=0}的性质进行了研究,如P~0(α)类的凸像和星象半径估计、偏差定理、像域面积的估计、拟共形性,其中得到的凸像和星象半径估计值改进了文献[8-9]中相应结果.此外,对包含P~0(α)的稳定单叶调和映照类(SHU)的Pre-Schwarz导数进行了考虑,得到了精确的上界估计.     

平面调和映照Schwarz-Pick引理的一个表述

设w(z)=P[F](z)为定义在单位圆盘D上的调和映照,满足w(0)=0和w(D)D,其中F为边界函数.本文利用Poisson积分和方向导数得到w(z)的Schwarz-Pick引理的一个表述如下:A-w(z)≤maxo≤x≤1h(x,r),这里h(x,r)如(3.2)所示,为x的连续函数.进一步地,本文证明对于某些边界函数F,上述估计是精确的.     

单位圆到水平条形无界区域的调和拟共形映照

研究单位圆盘到水平条形无界区域在原点满足一定规范条件的单叶保向调和映照的解析特征.推导出该类单叶调和映照的解析表示法.得到单位圆盘到水平条形无界区域在原点满足一定规范条件的单叶保向调和映照f(z)成为调和拟共形映照的充分必要条件,对该类调和拟共形映照的系数作出精确估计.作为应用,证明了该类调和拟共形映照的像在欧氏度量下的长度和面积与原像在非欧度量下的偏差定理.本文的结果改进和推广了由Hengartner和Schober所得的相应结论.     

微分算子作用下平面调和映照的单叶半径和 Bloch 常数估计

利用单位圆$D=\{z\mid | z |<1\}$上单叶调和映照的稳定性特征, 研究平面调和映照$f=h+\ov g$在微分算子 $L=z \frac {\partial }{\partial z}-\ov {z}\frac {\partial}{\partial {\ov z}}$作用下调和映照的单叶半径和 Bloch 常数估计, 得到一些精确性结论, 并改进了近期由刘名生和刘志文所得的相应结果.     

调和映照的星象半径

基于对单叶调和函数系数估计的猜想,对定义在单位圆盘上的调和映照类的星象半径进行研究.首先研究系数在满足一定条件下的调和映照类的星象半径,得到其精确的估计,其次研究两类调和函数的卷积的星象半径,所得到的结论也是精确的.     

C~n中单位多圆柱上一类B型α次准凸映射齐次展开式各项的精确估计

本文给出Cn中单位多圆柱上一类B型α次准凸映射f(z)齐次展开式各项的精确估计,其中f(z)=(f1(z),f2(z),...,fn(z))T是k折对称映射(或z=0是f(z)-z的k+1阶零点),且满足sup∥z∥=1,∥w∥=1∥Dmf(0)(zm-1,w)∥=sup∥z∥=1∥Dmf(0)(zm)∥,m=2,3,...所得到的估计包含已有文献的许多结论.     

平面有界调和函数的B1och常数估计

得到了一个平面有界调和函数系数的精确估计式,由此改进了平面有界调和映照的Bloch常数估计,并相应地改进了双调和映照的单叶半径估计.这些结果是Grigoryan,Huang和Abdulhadi等所得结论的推广.     

平面有界调和函数的Bloch常数估计

得到了一个平面有界调和函数系数的精确估计式,由此改进了平面有界调和映照的Bloch常数估计,并相应地改进了双调和映照的单叶半径估计.这些结果是Grigoryan,Huang和Abdulhadi等所得结论的推广.     

积分算子下调和映照的单叶半径估计

研究单位圆盘上的调和映照在不同条件下积分算子I_f(z)的单叶半径问题,得到在满足不同条件下的Landau型常数,其结论是渐进精确的;其次在调和映照f(z)有界的情况下,研究积分算子I_f(z)的有界性,其结论也是渐进精确的.     

The Distortion Theorems for Harmonic Mappings with Negative Coefficient Analytic Parts

Some sharp estimates for coefficients, distortion and the growth order are obtained for harmonic mappings $f ∈ TL^α_H$which are locally univalent harmonic mappings in the unit disk $\mathbb{D}:=\{z:|z| < 1\}$. Moreover, denoting the subclass $TS^α_H$ of the normalized univalent harmonic mappings, we also estimate the growth of $|f|,$ $f ∈ TS^α_H,$ and their covering theorems.     

The Distortion Theorems for Harmonic Mappings with Negative Coefficient Analytic Parts

Some sharp estimates for coefficients, distortion and the growth order are obtained for harmonic mappings $f \in TL^{\alpha}_H,$ which are locally univalent harmonic mappings in the unit disk $\mathbb{D}:=\{z:|z|<1\}.$ Moreover, denoting the subclass $TS^{\alpha}_H$ of the normalized univalent harmonic mappings, we also estimate the growth of $|f|,$ $f \in TS^α_H,$ and their covering theorems.     

Landau and Bloch theorems for harmonic mappings

Chen, Gauthier and Hengartner obtained some versions of Landau's theorem for bounded harmonic mappings and Bloch's theorem for harmonic mappings which are quasiregular and for those which are open. Later, Dorff and Nowak improved their estimates concerning Landau's theorem. In this study, we improve these last results by obtaining sharp coefficient estimates for properly normalized harmonic mappings. Furthermore, our estimates allow us to improve Bloch constant for open harmonic mappings.     

Properties of Some Classes of Planar Harmonic and Planar Biharmonic Mappings

The aim of this paper is to investigate some properties of planar harmonic and biharmonic mappings. First, we use the Schwarz lemma and the improved estimates for the coefficients of planar harmonic mappings to generalize earlier results related to Landau’s constants for harmonic and biharmonic mappings. Second, we obtain a new Landau’s Theorem for a certain class of biharmonic mappings. At the end, we derive a relationship between the images of the linear connectivity of the unit disk \mathbbD{\mathbb{D}} under the planar harmonic mappings f=h+[`(g)]{f=h+\overline{g}} and under their corresponding analytic counterparts F = h − g.     

On the Analytic Part of Univalent Harmonic Mappings

In this article we obtain two sharp results concerning the analytic part of harmonic mappings \(f=h+\overline{g}\) from the class \(\mathcal {S}^0_H(\mathcal {S})\) which was recently introduced by Ponnusamy and Sairam Kaliraj. For example, we get the sharp estimate for \(|\arg h'(z)|\) in the case when \(|z| \le 1/\sqrt{2}\) and obtain the sharp radius of convexity for h. Our approach is applicable to a more general situation. Finally, we determine simple condition on the analytic part of univalent harmonic mappings so that it is in \(H_p\) spaces for \(0<p<1/3\).     

多复变数某些双全纯映射子族精确的系数估计

作者建立了复Banach空间单位球上和Cⁿ中单位多圆柱上限制条件下双全纯映射齐次展开式的精确估计和Fekete-Szeg?不等式,同时给出Cⁿ中D_p1,p2,…,pn={z∈Cⁿ:∑ni=1|zl|^pl<1}(pl>1,l=1,2,…,n)上限制条件下双全纯映射主要系数的精确估计和Fekete-Szeg?不等式.所得结果推广了单复变几何函数论中相应的经典结论.     

Estimates on Bloch constants for planar harmonic mappings

The Bloch constants for quasiregular harmonic mappings and open planar harmonic mappings are considered. Better estimates are obtained. The results, presented in this paper, improve the one made by Chen et al. and Grigoryan. This work was supported by the Research Foundation for Doctor Programme (Grant No. 20050574002) and the National Natural Science Foundation of China (Grant No. 10471048)     

The Sharp Estimates of all Homogeneous Expansions for a Class of Quasi-convex Mappings on the Unit Polydisk in Cn

In this paper,the sharp estimates of all homogeneous expansions for f are established,where f(z)=(f1(z),f2(z),…,fn(z))'is a k-fold symmetric quasi-convex mapping defined on the unit polydisk in Cn and theorem for a k-fold symmetric quasi-convex mapping are established as well.These results show that in the case of quasi-convex mappings,Bieberbach conjecture in several complex variables is partly proved,and many known results are generalized.     

Sharp Growth Theorems and Coefficient Bounds for Starlike Mappings in Several Complex Variables

Let B be the unit ball in a complex Banach space. Let S^＊k＋1（B） be the family of normalized starlike mappings f on B such that z = 0 is a zero of order k ＋ 1 of f（z） - z. The authors obtain sharp growth and covering theorems, as well as sharp coefficient bounds for various subsets of S^＊k＋1（B）.