低孔隙度疏松铝的高压声速与冲击熔化

对含微孔洞疏松度m=1.04的疏松铝进行了冲击加载-卸载实验,利用DISAR(distance interferometer system for any reflector)测得了53至99 GPa五个冲击压力下疏松铝/LiF界面粒子速度波剖面,获得了各压力下的纵波声速和其中三个压力点的体波声速,确定出疏松铝的冲击熔化压力约为81 GPa,确定出高压下冲击熔化前的泊松比约为0.372.通过分析,微孔洞明显降低了冲击熔化压力,引起的非谐振效应明显,状态方程计算中考虑非谐效应,非谐因子l 关键词： 低孔隙度 疏松铝 声速 冲击熔化     

三元Co-Cu-Pb偏晶合金的快速凝固组织形成规律研究

在自由落体条件下实现了三元Co-Cu-Pb合金的液相分离与快速凝固. 实验发现,随液滴直径减小,Co₅₁Cu₄₇Pb₂合金液滴发生由枝晶→两层壳核→枝晶组织的转变,Co₄₇Cu₄₄Pb₉合金液滴的组织形态由壳核组织演化为均匀组织. 两种合金的快速凝固组织均由α(Co),(Cu)和(Pb)固溶体三相组成,α(Co)和(Cu)相主要以枝晶方式生长,(Pb)相分布在(Cu)枝晶间. 关键词： 液相分离 偏晶合金 快速凝固 自由落体     

Existence of solutions for a damped nonlinear impulsive problem with Dirichlet boundary conditions

In this paper, we consider the existence of solutions for second‐order nonlinear damped impulsive differential equations with Dirichlet boundary condition. By critical point theory, we obtain some existence theorems of solutions for the nonlinear problem. We extend and improve some recent results. Copyright © 2013 John Wiley & Sons, Ltd.     

Plancherel–Rotach Asymptotic Expansion for Some Polynomials from Indeterminate Moment Problems

We study the Plancherel–Rotach asymptotics of four families of orthogonal polynomials: the Chen–Ismail polynomials, the Berg–Letessier–Valent polynomials, and the Conrad–Flajolet polynomials I and II. All these polynomials arise in indeterminate moment problems, and three of them are birth and death process polynomials with cubic or quartic rates. We employ a difference equation asymptotic technique due to Z. Wang and R. Wong. Our analysis leads to a conjecture about large degree behavior of polynomials orthogonal with respect to solutions of indeterminate moment problems.     

Probabilistic interpretation for a system of quasilinear parabolic partial differential equation combined with algebra equations

In this paper, we study a kind of system of second order quasilinear parabolic partial differential equation combined with algebra equations. Introducing a family of coupled forward–backward stochastic differential equations, and by virtue of some delicate analysis techniques, we give a probabilistic interpretation for it in the viscosity sense.     

Chinese companies distress prediction: an application of data envelopment analysis

Bankruptcy prediction is a key part in corporate credit risk management. Traditional bankruptcy prediction models employ financial ratios or market prices to predict bankruptcy or financial distress prior to its occurrence. We investigate the predictive accuracy of corporate efficiency measures along with standard financial ratios in predicting corporate distress in Chinese companies. Data Envelopment Analysis (DEA) is used to measure corporate efficiency. In contrast to previous applications of DEA in credit risk modelling where it was used to generate a single efficiency—Technical Efficiency (TE), we assume Variable Returns to Scale, and decompose TE into Pure Technical Efficiency and Scale Efficiency. These measures are introduced into Logistic Regression to predict the probability of distress, along with the level of Returns to Scale. Effects of efficiency variables are allowed to vary across industries through the use of interaction terms, while the financial ratios are assumed to have the same effects across all sectors. The results show that the predictive power of the model is improved by this corporate efficiency information.     

Numerical algorithm based on an implicit fully discrete local discontinuous Galerkin method for the fractional diffusion-wave equation

In this paper, we consider the numerical approximation for the fractional diffusion-wave equation. The main purpose of this paper is to solve and analyze this problem by introducing an implicit fully discrete local discontinuous Galerkin method. The method is based on a finite difference scheme in time and local discontinuous Galerkin methods in space. By choosing the numerical fluxes carefully we prove that our scheme is unconditionally stable and get L ₂ error estimates of \(O(h^{k+1}+(\Delta t)^{2}+(\Delta t)^{\frac {\alpha }{2}}h^{k+1})\) . Finally numerical examples are performed to illustrate the efficiency and the accuracy of the method.     

Combinatorial constructions for optimal 2-D optical orthogonal codes with AM-OPPTS property

We develop a new one-to-one correspondence between a two-dimensional (m × n, k, ρ) optical orthogonal code (2-D (m × n, k, ρ)-OOC) with AM-OPPTS (at most one-pulse per time slot) property and a certain combinatorial subject, called an n-cyclic holey packing of type m ⁿ . By this link, an upper bound on the size of a 2-D (m × n, k, ρ)-OOC with AM-OPPTS property is derived. Afterwards, we employ combinatorial methods to construct infinitely many 2-D (m × n, k, 1)-OOCs with AM-OPPTS property, whose existence was previously unknown. All these constructions meet the upper bounds with equality and are thus optimal.     

长吻鮠肝脏线粒体DNA的研究

采用密度梯度离心法及ＤＮａｓｅⅠ、ＲＮａｓｅ消化法制备并纯化了长吻鮠　（ＬｅｉｏｃａｓｓｉｓＬｏｎｇｉｒｏｓｔｒｉｓ）肝脏线粒体ＤＮＡ（ｍｔＤＮＡ）．用９种限制性内切酶对ｍｔＤＮＡ进行了分析．ＸｈｏⅠ、ＢｇｌⅡ、ＥｃｏＲⅠ、ＰｓｔⅠ、ＢｇｌⅠ、ＢａｍＨⅠ、ＸｂａⅠ、ＨｉｎｄⅢ、ＳａｌⅠ在长吻　ｍｔＤＮＡ分子上分别具１、３、３、２、１、２、４、７、０个切点．ｍｔＤＮＡ分子量约１０．３１×１０５道尔顿，大小为１６．６９ｋｂ．根据单酶和双酶解片段的数目和分子量，建立了长吻　ｍｔＤＮＡ的限制性酶切图谱．     

KERNEL ESTIMATION OF HIGHER DERIVATIVES OF DENSITY AND HAZARD RATE FUNCTION FOR TRUNCATED AND CENSORED DEPENDENT DATA

Based on left truncated and right censored dependent data, the estimators of higher derivatives of density function and hazard rate function are given by kernel smoothing method. When observed data exhibit α-mixing dependence, local properties including strong consistency and law of iterated logarithm are presented. Moreover, when the mode estimator is defined as the random variable that maximizes the kernel density estimator, the asymptotic normality of the mode estimator is established.