Alternants for generalized convex functions

In this paper we consider the problem of best uniform approximation by elements of WT-spaces. In particular, we investigate the structure of the corresponding error function when the function to be approximated is generalized convex with respect to a WT-space. The principal concept involved is that of an alternation element, an element for which the error function takes on its norm with alternating signs a specified number of times. This approach has been employed by Jones, Karlovitz [4], Sommer, Strauss [10], Nurnberger, Sommer [7] and Barrar, Loeb [2]. Much of the material in this paper was inspired by a paper of Amir and Ziegler [1] . A new characterization of WT-spaces in terms of alternation elements is given.     

基于可信第三方的防欺骗视觉密码分享方案

传统的视觉密码方案需要参与者相互验证,因此存在着一系列检测过程,不够简洁、应用不够广泛等问题;基于这一点,提出了一种需要引入第三方的防欺骗视觉密码分享方案;该方案采用异或(XOR)运算,利用可信第三方和受怀疑的分享图像能否恢复出验证图像来实现真实性检验,可直接验证分发者和参与者的欺骗行为,具有方便快捷和不受存取结构限制的特点。     

Calculating the branch points of the eigenvalues of the Coulomb spheroidal wave equation

A method for computing the eigenvalues λ _mn (b, c) and the eigenfunctions of the Coulomb spheroidal wave equation is proposed in the case of complex parameters b and c. The solution is represented as a combination of power series expansions that are then matched at a single point. An extensive numerical analysis shows that certain b _s and c _s are second-order branch points for λ _mn (b, c) with different indices n ₁ and n ₂, so that the eigenvalues at these points are double. Padé approximants, quadratic Hermite-Padé approximants, the finite element method, and the generalized Newton method are used to compute the branch points b _s and c _s and the double eigenvalues to high accuracy. A large number of these singular points are calculated.     

The structure and distances in Yule recursive trees

Based on uniform recursive trees, we introduce random trees with the factor of time, which are named Yule recursive trees. The structure and the distance between the vertices in Yule recursive trees are investigated in this paper. For arbitrary time t > 0, we first give the probability that a Yule recursive tree Y_t is isomorphic to a given rooted tree γ; and then prove that the asymptotic distribution of ζ_t,m, the number of the branches of size m, is the Poisson distribution with parameter λ = 1/m. Finally, two types of distance between vertices in Yule recursive trees are studied, and some limit theorems for them are established.© 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007     

LIMITING BEHAVIOR OF UNIFORM RECURSIVE TREES

The authors consider the limiting behavior of various branches in a uniform recursive tree with size growing to infinity.The limiting distribution ofζ_(n,m),the number of branches with size m in a uniform recursive tree of order n,converges weakly to a Poisson distribution with parameter 1/m with convergence of all moments.The size of any large branch tends to infinity almost surely.     

一类非凸不可微规划的算法

讨论一类带非凸不可微函数约束的非凸不可微规划的求解,提出一种基于分枝定界技巧的算法,该算法具有全局收敛性．     

Far infrared sub-nanosecond pulse generation in GaP with a time-synchronized mode-locked double-frequency Nd: Glass laser system

Light pulses of 149 m wavelength and 700 ps duration are generated by non-collinear phase-matched difference frequency mixing of laser pulses at 1053.5 and 1061 nm in a (110) cut GaP crystal. The pump laser pulses are generated in a time-synchronized mode-locked double-frequency Nd:glass laser system consisting of a silicate glass branch and a phosphate glass branch. A photon conversion efficiency of 4 × 10^–6 is achieved. The non-linear susceptibility constant of GaP is determined to be d ₁₄ = (10 ± 1) pm V^–1.     

Models of Curves and Finite Covers

Let K be a discrete valuation field with ring of integers O _K .Letf : X ! Y be a finite morphism of curves over K. In this article, we study some possible relationships between the models over O K of X and of Y. Three such relationships are listed below. Consider a Galois cover f : X ! Y of degree prime to the characteristic of the residue field, with branch locus B. We show that if Y has semi-stable reduction over K,thenX achieves semi-stable reduction over some explicit tame extension of K.B/.WhenK is strictly henselian, we determine the minimal extension L=K with the property that X L has semi-stable reduction. Let f : X ! Y be a finite morphism, with g.Y/ > 2. We show that if X has a stable model X over O _K ,thenY has a stable model Y over O _K , and the morphism f extends to a morphism X ! Y. ! Y. Finally, given any finite morphism f : X ! Y, is it possible to choose suitable regular models X and Y of X and Y over O _K such that f extends to a finite morphism X ! Y ?As wasshown by Abhyankar, the answer is negative in general. We present counterexamples in rather general situ-ations, with f a cyclic cover of any order > 4. On the other hand, we prove, without any hypotheses on the residual characteristic, that this extension problem has a positive solution when f is cyclic of order 2 or 3.     

深圳特区报创新发展模式研究

深圳特区报不断创新新闻理念，努力办成思想性、实用性的综合型党报；以建立现代企业制度为目标．创新报业经营管理体制，尝试现代企业法人治理结构的构建；以现代整合营销手段，实施差异化、分众化策略，提升报业的竞争力，成为我国地方党报做强做大的典范，被誉为“特区报现象”。解读特区报竞争力不断提升的奥秘，对其他地方党报的改革发展有着重要的启示作用。     

基于用户需求的高校图书馆分馆服务模式探析

分馆模式被广泛应用于高校图书馆建设之中,如何推动分馆服务创新,开创分馆服务的新局面成为当前高校图书馆分馆工作的重点.通过对用户需求的分析,提出高校图书馆分馆的服务定位,并探索分馆服务模式.