Beurling-Ahlfors扩张的伸张函数与ID-同胚

本文研究实轴上同胚在上半平面的扩张.利用拟对称函数ρ对伸张函数D作了较精细的估计.同时借助于诱导的边界函数对D、ρ在边界附近的性质作了进一步刻划.作为应用,我们分别给出上半平面存在ID-同胚扩张和IID-同胚扩张的充分条件.     

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.     

平面上同分母有理点的稠密性及其应用

证明了实平面上同分母有理点集的稠密性.作为此结果的应用,构造了实平面上的一个简单函数,此函数说明实平面上具有稠密不连续点集的Riemann可积函数是存在的.     

关于Beurling和Ahlfors的一个定理的证明

<正> 实轴到自身的保持定向的同胚μ叫作ρ拟对称的，如果它满足下列条件：■对一切实数x及t≠0.1956年A.Beurling与L.Ahlfors证明了一个重要定理:对于任意给定的ρ拟对称函数μ,总存在一个上半平面到自身的K拟共形映照,以μ为边界对应,而K有下述估计式:     

正实轴上的Riemann边值问题

本文研究正实轴上的Riemann边值问题.首先,引入沿正实轴剖开的复平面上的全纯函数在无穷远点和原点处主部及阶的概念,相比于经典意义下,这个概念更为广泛.其次,讨论了正实轴上Cauchy型积分和Cauchy主值积分在无穷远点和原点处的性质.基于此,以正实轴为跳跃曲线的分区全纯函数的Riemann边值问题得以详细解决.这个过程有别于经典意义下有限曲线上的Riemann边值问题,且比整个实轴上的Riemann边值问题更为复杂.最后,作为例子讨论了一类矩阵值函数的边值问题,该问题对于正实轴上正交多项式的渐近分析有重要意义.     

典型域上高阶Fréechet导数的Schwarz-Pick估计

本文给出了典型域上带正实部的全纯函数高阶Fr¶echet 导数的Schwarz-Pick 估计. 推广了单位圆盘和单位球上带正实部的全纯函数高阶偏导数的Schwarz-Pick 估计.     

半平面中解析函数的积分表示

本文证明了半平面中满足某些限制增长条件的解析函数可以用加权Blaschke乘积和在半平面边界上的积分之和表示出来,这一结果改进了在半平面为指数型解析函数的经典结果.     

正则的正实部函数的导数估计

讨论了正则的正实部函数的导数估计问题,利用正实部函数的性质,得到三阶导数、四阶导数的准确估计式.     

含一条裂纹的半平板不完全焊接问题

设弹性平面由上、下半平面Z~±沿实轴X不完全焊接而成,Z~+内有一条位于虚轴Y上长2a的裂纹,在x轴上有裂纹,Z~±的弹性常数分别为k~±,μ~±(各向同性),设γ_1,γ_2上正负侧的外力大小相同方向相反,分别为,并设在无穷远处无应力和转动。     

实轴上的双解析函数Riemann边值逆问题

提出了一类实轴上的双解析函数Riemann边值逆问题.先消去参变未知函数,再采用易于推广的矩阵形式记法,可把问题转化为两个实轴上的解析函数Riemann边值问题.利用经典的Riemann边值问题理论,讨论了该问题正则型情况的解法,得到了它的可解性定理.     

右半平面上Laplace-Stieltjes变换的值分布

对右半平面上τ(2<τ<+∞)级Laplace-Stieltjes变换,在一定条件下,在虚轴上必有一个涉及小函数关于型函数的Borel点;对右半平面上无穷级Laplace-Stieltjes变换,在一定条件下,在虚轴上必有一个涉及小函数的无穷级Borel点.     

μ(z) -同胚的边界性质

该文讨论μ(z) -同胚的边界性质.给出了一个充分条件,使得上半平面的μ(z) -自同胚可以拓扑地向边界延拓. 用μ(z) -同胚的伸张函数估计了ρ -函数.     

On some criteria for completely regular growth of entire functions of exponential type

This paper sharpens the author’s previous results concerning the completely regular growth of an entire function of exponential type all of whose zeros are simple, forming a sequence Λ = {λ_k} _k=1 ^∞ . For a function with real zeros, we write the growth regularity conditions (on the real axis and on the entire plane) in terms of lower bounds only for the absolute value of the derivative at the points λ_k. We also obtain an analog of Krein’s theorem concerning the functions whose inverse can be expanded in the corresponding series of simple fractions.     

Instability of solitons under flexure and twist of an elastic rod

We study the stability of planar soliton solutions of equations describing the dynamics of an infinite inextensible unshearable rod under three-dimensional spatial perturbations. As a result of linearization about the soliton solution, we obtain an inhomogeneous scalar equation. This equation leads to a generalized eigenvalue problem. To establish the instability, we must verify the existence of an unstable eigenvalue (an eigenvalue with a positive real part). The corresponding proof of the instability is done using a local construction of the Evans function depending only on the spectral parameter. This function is analytic in the right half of the complex plane and has at least one zero on the positive real axis coinciding with an unstable eigenvalue of the generalized spectral problem.     

On Oscillation of Functions with Bounded Spectral Band

In this paper, we consider extremal oscillatory properties of functions with bounded spectrum, i.e., with bounded support (in the sense of distributions) of the Fourier transform. For such functions f, we give criteria of extendability of }f} from the real axis to a function F on the complex plane with derivatives F ^(m) having no real zeros and without enlarging the width of spectrum. In particular, we give examples of functions $f$ from the real Paley–Wiener space such that every function f ^(m), m=0, 1,..., has a finite number of real zeros.     

Summation formulae on trigonometric functions

Trigonometric sums over the angles equally distributed on the upper half plane are investigated systematically. Their generating functions and explicit formulae are established through the combination of the formal power series method and partial fraction decompositions.     

涉及小函数的随机Dirichlet级数

对于右半平面上的ρ(0<ρ<∞)级随机Dirichlet级数,它几乎必然以虚轴 上每一点为其没有例外小函数的Borel点.     

半平面中解析函数的积分表示及在逼近中的应用

在该文中, 作者证明了满足一定增长性条件的右半平面上的解析函数可以由它在边界上的积分和其加权Blaschke乘积的和表示, 作为应用, 作者还考虑了指数多项式在实数轴上加权 Banach 空间C_α 中的完备性.     

Transmission Eigenvalues and the Riemann Zeta Function in Scattering Theory for Automorphic Forms on Fuchsian Groups of Type I

We introduce the concept of transmission eigenvalues in scattering theory for automorphic forms on fundamental domains generated by discrete groups acting on the hyperbolic upper half complex plane. In particular, we consider Fuchsian groups of type Ⅰ. Transmission eigenvalues are related to those eigen-parameters for which one can send an incident wave that produces no scattering. The notion of transmission eigenvalues, or non-scattering energies, is well studied in the Euclidean geometry, where in some cases these eigenvalues appear as zeros of the scattering matrix. As opposed to scattering poles, in hyperbolic geometry such a connection between zeros of the scattering matrix and non-scattering energies is not studied, and the goal of this paper is to do just this for particular arithmetic groups. For such groups, using existing deep results from analytic number theory, we reveal that the zeros of the scattering matrix, consequently non-scattering energies, are directly expressed in terms of the zeros of the Riemann zeta function. Weyl's asymptotic laws are provided for the eigenvalues in those cases along with estimates on their location in the complex plane.