Estimating the parameters of the Marshall-Olkin bivariate Weibull distribution by EM algorithm

In this paper we consider the Marshall-Olkin bivariate Weibull distribution. The Marshall-Olkin bivariate Weibull distribution is a singular distribution, whose both the marginals are univariate Weibull distributions. This is a generalization of the Marshall-Olkin bivariate exponential distribution. The cumulative joint distribution of the Marshall-Olkin bivariate Weibull distribution is a mixture of an absolute continuous distribution function and a singular distribution function. This distribution has four unknown parameters and it is observed that the maximum likelihood estimators of the unknown parameters cannot be obtained in explicit forms. In this paper we discuss about the computation of the maximum likelihood estimators of the unknown parameters using EM algorithm. We perform some simulations to see the performances of the EM algorithm and re-analyze one data set for illustrative purpose.     

能耗曲线在带钢热连轧负荷分配控制中的应用

主要介绍了带钢热连轧厚度控制中采用能耗曲线的方法,对轧机的负荷分配进行分析和设计,详细论述了能耗曲线的建立过程以及运用于实际生产过程中的轧制力分配和辊缝分配的控制方案,并给出了它们各自具体的控制原理、计算公式以及程序框图。该负荷分配方法用于在线,有较好的使用效果。     

GIS与SVG视域下低压配网单线图的自动化布局算法研究

以设备模型与拓扑连接关系为载体配网单线图自动化布局具备十分重要的现实意义.据此本文在GIS与SVG视域下开发设计了低压配网单线图自动化布局算法.首先分析低压配网单线图自动化成图思路;其次详细设计自动化布局算法;最后进行自动化布局算法实践应用流程规划.研究表明,低压配网单线图可基于移动终端展示,以缩放与平移实时呈现箱内设...     

供电网络优化设计的模拟退火算法

对供电网络优化设计提出了一种新算法。把供电网络优化设计问题抽象成图论问题，应用图论最优化方法解决该问题。同时提出了多边形变换方法，用模拟退火算法对供电网络进行优化设计，最终得到一个费用最小电网。     

因特网拓扑结构的幂律分析与建模研究

本文通过对因特网测量拓扑的幂律分布特征,包括frequency-degree幂律分布、degree-rank幂律分布与CCDF(d)-degree幂律分布的研究,发现因特网测量拓扑具有非常明显的frequency-degree幂律分布与degree-rank幂律分布规律。其中,frequency-degree幂律分布符合幂律指数为2.1406的分布规律,而degree-rank幂律分布则分为两部分,主体节点服从幂律指数为0.84639的分布,而度值最大的部分节点却符合幂律指数为0.29981的分布规律。在CCDF(d)-de-gree幂律分布研究中发现,Weibull分布要比幂律分布拟合效果更好。也就是说,对于本文Internet拓扑来说,其节点度的CCDF不一定符合幂律分布。根据frequency-degree幂律幂指数2.1406,本文在BA模型的基础上提出了改进的BA模型,确定网络增长连边概率方程中的ε为0.10812。     

A new generalization of the Waring distribution

A tetraparametric univariate distribution generated by the Gaussian hypergeometric function that includes the Waring and the generalized Waring distributions as particular cases is presented. This distribution is expressed as a generalized beta type I mixture of a negative binomial distribution, in such a way that the variance of the tetraparametric model can be split into three components: randomness, proneness and liability. These results are extensions of known analogous properties of the generalized Waring distribution. Two applications in the fields of sport and economy are included in order to illustrate the utility of the new distribution compared with the generalized Waring distribution.     

Static Forecasting of the Execution Times of Complexes of Interrelated Jobs in the Multiprocessor Computer Systems

Consideration was given to a procedure of approximate forecasting of the execution times of the complexes of interrelated jobs in the multiprocessor computer systems with the Erlangian execution time of each job. This distribution is used as a tool for modeling the normal distribution. The order and parameter of the approximating Erlangian distribution are chosen from the parameters of the normal distribution.__________Translated from Avtomatika i Telemekhanika, No. 6, 2005, pp. 89–103.Original Russian Text Copyright © 2005 by Ivanov, Ignatushchenko, Mikhailov.     

A new generalization of the Waring distribution

A tetraparametric univariate distribution generated by the Gaussian hypergeometric function that includes the Waring and the generalized Waring distributions as particular cases is presented. This distribution is expressed as a generalized beta type I mixture of a negative binomial distribution, in such a way that the variance of the tetraparametric model can be split into three components: randomness, proneness and liability. These results are extensions of known analogous properties of the generalized Waring distribution. Two applications in the fields of sport and economy are included in order to illustrate the utility of the new distribution compared with the generalized Waring distribution.     

基于导体系统电容对变压器电容的研究

电容器是一种常用的电子元件,不管是独立导体,还是多个导体组成的系统,都可构成电容器,对于多个导体组成的系统来说,它们所构成的电容可分为自部分电容和互部分电容,这些电容在有的电路中可以看成是分布电容。变压器是一个多导体系统特例,它是由铁芯(磁芯)、绕组、屏蔽层(接地)等导体构成,该系统所形成的分布电容对有的电路影响非常大,因此为了讨论该问题,本文从导体系统电容出发,系统地阐述变压器分布电容的形成、危害及克服办法。     

Bayes网络最优近似下边缘分布的不变性

删除Bayes网络中的弧以减小网络结构的复杂性，从而降低概率推理算法的复杂度是一种对Bayes网络进行近似的方法．该文讨论了在删除Bayes网络中的一条弧之后得到的最优近似概率分布和原概率分布之间的关系，证明了对满足一定条件的结点子集而言，其边缘概率分布在近似以后具有不变性．     

On the convergence of a class of estimation of distribution algorithms

We investigate the global convergence of estimation of distribution algorithms (EDAs). In EDAs, the distribution is estimated from a set of selected elements, i.e., the parent set, and then the estimated distribution model is used to generate new elements. In this paper, we prove that: 1) if the distribution of the new elements matches that of the parent set exactly, the algorithms will converge to the global optimum under three widely used selection schemes and 2) a factorized distribution algorithm converges globally under proportional selection.     

Stress Concentration around the Embedding of the Honeycomb Sandwich Structure

Honeycomb structures and other sandwich materials are being used as designs which have demanded high-stiffness and lightweight structures. The embedding design can further decrease the total weight of the products. Embedding will inevitably generate defect of the honeycomb and cause stress concentration. This study mainly discusses the tensile stress distribution near the defect in a quantitative way with the finite element and analytical method. The prediction function of the stress distribution is proposed. X and y directional stress distribution properties are found. These results are proved to be validate through a representative defect case. The bending stress distribution is investigated through material mechanics method and the prediction equation of the maximum bending stress is given.     

Estimating turning points of the failure rate of the extended Weibull distribution

Marshall and Olkin (1997) proposed a way of introducing a parameter, called the tilt parameter, to expand a family of distributions. In this paper we compare the extended distribution and the original distribution with respect to some stochastic orderings. Also we investigate thoroughly the monotonicity of the failure rate of the resulting distribution when the baseline distribution is taken as Weibull. It turns out that the failure rate is increasing, decreasing, or non-monotonic with one or two turning points depending on the parameters. For non-monotonic types, the turning points of the failure rate are estimated and their confidence intervals are provided. Simulation studies are carried out to examine the performance of these intervals. An example is provided to illustrate the procedure.     

On the Distribution of Software Faults

The Pareto principle is often used to describe how faults in large software systems are distributed over modules. A recent paper by Andersson and Runeson again confirmed the Pareto principle of fault distribution. In this paper, we show that the distribution of software faults can be more precisely described as the Weibull distribution.     

森林动态演替现象的可视化模拟

由于自然环境、资源竞争、生长繁衍等因素的影响,森林中树木的空间分布格局不断发生着变化。本文基于森林生态学的相关理论,对森林的这种动态演替现象进行了研究和模拟。我们采用一种二维分布图的形式来着重展现森林演替过程中的自然稀疏、多树种演替和聚集生长三种重要的变化规律,并以此为基础,通过迭代推演的方式实现了森林景观动态演替过程的可视化模拟。模拟计算过程中,为了加速迭代推演过程中最耗时的树木相交测试,本文还提出一种“扩展边界的四叉树”方法,提高了计算效率。本文在生成森林初始分布信息时参考了有关森林空间数据的概念,能够生成符合林业上树木胸径分布的森林数据。本文技术方法不仅可应用于影视动画、虚拟现实等领域,而且在林业科学研究与应用上也具有潜在的应用价值。     

Calculation of the random-variable distribution law

In this paper, continuous random variables are classified, three systems of continuous distributions are constructed, and the principle of the robust method for the calculation of the distribution law (including the rank distribution) and parameter estimates and the generic method of moments are described. Universal laws for the distribution and aging of publications are validated.     

Multivariable goodness tests and approximation of the residues of quadratic forms

Consideration was given to the omega square Cramer-von Mises tests intended to verify the goodness hypothesis about the distribution of the observed multivariable random vector with the distribution in the unit cube. The limit distribution of the statistics of these tests was defined by the distribution of an infinite quadratic form in the normal random variables. For convenience of computing its distribution, the residue of the quadratic form was approximated by a finite linear combination of the χ²-distributed random variables. Formulas for determination of the residue parameters were established.     

激光海洋测深仪激光海面入射点分布优化设计

通过对激光测深仪的激光海面入射点分布的研究,得到了其疏密程度与扫描方式、扫描电机转速、激光器重复频率和飞机飞行速度等参量之间的关系,并对激光海面入射点分布进行了优化设计。提出使用调整激光器触发信号的码盘脉冲校正海面激光入射点分布不均匀的方法,并且讨论了实际的测量点的位置坐标与激光海面入射点位置坐标的确定。     

第三方物流综合代理的EDI物资情报系统

以往的电子商务过程忽略了物流的过程 ,针对此问题阐述了电子商务与其物流的内在联系 ,提出了第三方物流代理系统 ,为物流企业提供了更加详尽的信息资源 ,使物流企业工作程序化、连续化 ,使物流业能迅速对市场变化作出反映 ,并及时作出调整。     

Stochastic distribution of the required coefficient of friction for level walking--an in-depth study

This study investigated the stochastic distribution of the required coefficient of friction (RCOF) which is a critical element for estimating slip probability. Fifty participants walked under four walking conditions. The results of the Kolmogorov-Smirnov two-sample test indicate that 76% of the RCOF data showed a difference in distribution between both feet for the same participant under each walking condition; the data from both feet were kept separate. The results of the Kolmogorov-Smirnov goodness-of-fit test indicate that most of the distribution of the RCOF appears to have a good match with the normal (85.5%), log-normal (84.5%) and Weibull distributions (81.5%). However, approximately 7.75% of the cases did not have a match with any of these distributions. It is reasonable to use the normal distribution for representation of the RCOF distribution due to its simplicity and familiarity, but each foot had a different distribution from the other foot in 76% of cases. PRACTITIONER SUMMARY: The stochastic distribution of the required coefficient of friction (RCOF) was investigated for use in a statistical model to improve the estimate of slip probability in risk assessment. The results indicate that 85.5% of the distribution of the RCOF appears to have a good match with the normal distribution.