Iterative Reconstructions in Irregular Sampling With Derivatives

Finite energy band-limited functions are reconstructed iteratively from nonuniform sample values of the functions and its derivatives. It is shown that the maximum gap allowed between the sampling points increases linearly with the number of derivatives considered. Moreover, a more precise result is presented for the first derivative case and another reconstruction of the functions using the frame algorithm is deduced.     

Irregular Sampling of Generalized Harmonizable Processes

Abstract

In this note an irregular sampling expansion for bandlimited harmonizable processes is obtained by employing contour integral techniques in the vector-valued analytic functions setting. In so doing, we use the integral representation of a harmonizable process with respect to a vector measure.     

不规则多生成子Gabor框架及其对偶

对给定的φ_0,…,φ_(r-1)∈L~2(R)和a_0,b_0,…,a_(r-1)1,b_(r-1)>0,本文考虑不规则多生成子Gabor系统{E_(mb_l)T_(na_l)φ_l,m,n∈Z,l=0,…,r-1}.本文给出了该系统成为L~2(R)框架的充要条件;得到了不规则多生成子Gabor框架与其对偶之间关系的刻画.特别地,给出了一类多生成子Gabor框架及其对偶的显式构造.     

Universal Sampling and Interpolation of Band-Limited Signals

We ask if there exist discrete “universal” sets of given finite density such that every signal f with bounded spectrum of small measure can be recovered from the samples . We prove that uniqueness in this problem can be achieved in general situation. On the other hand, for stable reconstruction it is crucial whether the spectrum is compact or dense. Received: February 2007, Accepted: May 2007     

Phaseless Sampling and Reconstruction of Real-Valued Signals in Shift-Invariant Spaces

Sampling in shift-invariant spaces is a realistic model for signals with smooth spectrum. In this paper, we consider phaseless sampling and reconstruction of real-valued signals in a high-dimensional shift-invariant space from their magnitude measurements on the whole Euclidean space and from their phaseless samples taken on a discrete set with finite sampling density. The determination of a signal in a shift-invariant space, up to a sign, by its magnitude measurements on the whole Euclidean space has been shown in the literature to be equivalent to its nonseparability. In this paper, we introduce an undirected graph associated with the signal in a shift-invariant space and use connectivity of the graph to characterize nonseparability of the signal. Under the local complement property assumption on a shift-invariant space, we find a discrete set with finite sampling density such that nonseparable signals in the shift-invariant space can be reconstructed in a stable way from their phaseless samples taken on that set. In this paper, we also propose a reconstruction algorithm which provides an approximation to the original signal when its noisy phaseless samples are available only. Finally, numerical simulations are performed to demonstrate the robustness of the proposed algorithm to reconstruct box spline signals from their noisy phaseless samples.

     

多项式及其导数不等式

设‖·‖是 ( -∞ ,+∞ )上关于权 e- t2 的 L2范数 ,本文证明了对一切次数不超过 n的多项式f ( x) ,有‖ f′‖2 ≤ A‖ f″‖ 2 +( 2 n-4An( n-1 ) )‖ f‖ 2 ,这里 A只要满足 A≤ 14( n-1 ) .     

变形Rappoport算子及其导数

本文研究了变形Ｒａｐｐｏｒｔ算子的导数；其收敛速度与函数的光滑性之间的关系，空间是Ｌｐ（１≤ｐ≤∞）．     

On Partially Irregular Almost Periodic Solutions of Weakly Nonlinear Ordinary Differential Systems

For weakly nonlinear almost periodic ordinary differential systems, we obtain conditions for the existence of partially irregular almost periodic solutions and propose algorithms for their construction. __________ Translated from Ukrains'kyi Matematychnyi Zhurnal, Vol. 57, No. 8, pp. 1123 – 1130, August, 2005.     

整函数及其导数的唯一性定理

主要在涉及更值的情况下得到整函数及其导数具有两个公共值时的一个唯一性定理.     

Boundary Behavior of Universal Taylor Series and Their Derivatives

For a given first category subset E of the unit circle and any given holomorphic function g on the open unit disk, we construct a universal Taylor series f on the open unit disk, such that, for every n = 0,1,2,..., f⁽ⁿ⁾ is close to g⁽ⁿ⁾ on a set of radii having endpoints in E. Therefore, there is a universal Taylor series f, such that f and all its derivatives have radial limits on all radii with endpoints in E. On the other hand, we prove that if f is a universal Taylor series on the open unit disk, then there exists a residual set G of the unit circle, such that for every strictly positive integer n, the derivative f⁽ⁿ⁾ is unbounded on all radii with endpoints in the set G.     

亚纯函数多项式结合其导数的零点

研究p~t[f] aP~2[f](a≠0为常数）的零点问题．     

Normal Families and Uniqueness of Entire Functions and Their Derivatives

Let f be a nonconstant entire function; let k ≥ 2 be a positive integer; and let a be a nonzero complex number. If f（z） = a→f′（z） = a, and f′（z） = a →f^（k）（z） = a, then either f = Ce^λz ＋ a or f = Ce^λz ＋ a（λ - 1）/）λ, where C and ）, are nonzero constants with λ^k-1 = 1. The proof is based on the Wiman-Vlairon theory and the theory of normal families in an essential way.     

The Uniqueness of Entire Functions with Their Derivatives

§ 1.Introduction　 By a“meromorphic function” we mean a function that is meromorphic in the wholecomplex plane.It is assumed that the reader is familiar with notations of Nevanlinnatheory such as T(r,f) ,m(r,f) ,N (r,1f) ,S(r,f ) and so on that can be found,forinstance,in[1 ] or[2 ] .Let f and g be two meromorphic functions and a be a complexnumber. We say that f and g share the value a CM (counting multiplicity) if f -a andg-a have the same zeros with the same multiplicity,and denote th…