On Block Skip Free Transition Matrices and First Passage Times

Starting from an abstract setting which extends the property “skip free to the left” for transition matrices to a partition of the state space, we develop bounds for the mean hitting time of a Markov chain to an arbitrary subset from an arbitrary initial law. We apply our theory to the embedded Markov chains associated with the M/G/1 and the GI/M/1 queueing systems. We also illustrate its applicability with an asymptotic analysis of a non-reversible Markovian star queueing network with losses.     

Fast and Stable Algorithms for Computing and Sampling From the Noncentral Hypergeometric Distribution

Although the noncentral hypergeometric distribution underlies conditional inference for 2 × 2 tables, major statistical packages lack support for this distribution. This article introduces fast and stable algorithms for computing the noncentral hypergeometric distribution and for sampling from it. The algorithms avoid the expensive and explosive combinatorial numbers by using a recursive relation. The algorithms also take advantage of the sharp concentration of the distribution around its mode to save computing time. A modified inverse method substantially reduces the number of searches in generating a random deviate. The algorithms are implemented in a Java class, Hypergeometric, available on the World Wide Web.     

Reversed preservation of stochastic orders for random minima and maxima with applications

In this paper, reversed preservation properties of right spread order, total time on test order and increasing convex (concave) order when taking random minima and maxima are developed. In this context, reversed preservation properties of some ageing concepts are investigated under parallel (series) systems which are composed of a random number of i.i.d. components. Some applications in reliability and economics are given.     

Estimating the distribution of one-dimensional discrete scan statistics viewed as extremes of 1-dependent stationary sequences

Discrete one-dimensional scan statistics can be viewed as extremes of 1-dependent stationary sequences. A result of Haiman [1999. First passage time for some stationary processes. Stochastic Process. Appl. 80, 231–248] provides approximations of the distributions of extremes of 1-dependent stationary sequences together with sharp bounds for the corresponding errors. We apply this result to scan statistics generated by Bernoulli r.v.'s and to the charge problem.     

Occupancy numbers for dynamic heterogeneous populations: Estimate of particles lifetimes

A dynamic model of a heterogeneous population is studied. Particles belonging to a population are divided, at every time t, into a finite number of classes according to their types and the partition changes over time. The role of the occupancy numbers, namely the cardinality of each class, is highlighted. The relationship between the stochastic process of occupancy numbers and the process of particle types is analyzed. The main goal of this paper is the estimation of the lifetime of each particle at a given time t, when the observed data are the history of the process of the number of dead particles up to t. Furthermore, a discrete time approximation of the filter is given.     

Considerations on group-wise identical designs for linear mixed models

We consider a general class of mixed models, where the individual parameter vector is composed of a linear function of the population parameter vector plus an individual random effects vector. The linear function can vary for the different individuals. We show that the search for optimal designs for the estimation of the population parameter vector can be restricted to the class of group-wise identical designs, i.e., for each of the groups defined by the different linear functions only one individual elementary design has to be optimized. A way to apply the result to non-linear mixed models is described.     

三维有机超分子晶体：3-氨基-2-羧基吡嗪

通过溶液法培养了3-氨基-2-羧基吡嗪的单晶,利用单晶X-射线衍射法测定了其晶体结构。同时利用元素分析、红外光谱对其进行了表征。晶体学数据：单斜晶系,P2（1）/c空间群,a=3.7629（7）Ao,b=14.2098（3）Ao,c=10.9212（19）A°^,α=90°,β=99.182（3）°,γ=90°,V=576.47（18）A°^ 3,Z=4,ρcalc=1.603 g·cm^-3,R1=0.0527,WR2=0.1368。结构分析表明,3-氨基-2-羧基吡嗪分子通过氢键作用和π-π堆积作用连接成三维超分子网络结构。     

几种典型的烟气脱硫技术

烟气脱硫是控制二氧化硫污染的常用方法,我国的烟气脱硫技术研究从19世纪五十年代开始,目前已形成较多的应用技术。文中对国内几种典型的烟气脱硫技术的工艺流程、特点、应用情况及其发展做了介绍。     

内蒙古绒山羊KAP6-2全长cDNA的特征分析

选择10月份周岁绒山羊体侧部皮肤构建cDNA质粒文库,随机挑选克隆提取质粒,用M13正向通通用引物,测插入片段的序列,得到636个序列。与Genebank数据库比对后,发现有1个序列与小鼠的KAP6-2基因的期望值小于le-10,对其预期编码蛋白的氨基酸进行分析,建议绒山羊KAP6-2具有HGTps(高苷/酪氨酸蛋白,high glycine/tyrosine proteins)与富含半胱氨酸蛋白之间的中间特征。     

I~2C总线与PC机接口设计

介绍一种简单、成本低的 I2 C总线与 PC机的接口卡 ,普通微机便可以与 I2 C系列的外接设备数据传输 ,构成一个工业自动化生产过程的监控系统