Likelihood inference for the component lifetime distribution based on progressively censored parallel systems data

Point and interval estimators for the scale parameter of the component lifetime distribution of a k-component parallel system are obtained when the component lifetimes are assumed to be independently and identically exponentially distributed. We prove that the maximum likelihood estimator of the scale parameter based on progressively Type-II censored system lifetimes is unique and can be obtained by a fixed-point iteration procedure. In particular, we illustrate that the Newton–Raphson method does not converge for any initial value. Furthermore, exact confidence intervals are constructed by a transformation using normalized spacings and other component lifetime distributions including Weibull distribution are discussed.     

The competing risks analysis for parallel and series systems using Type-II progressive censoring

Abstract

Recently, the study of the lifetime of systems in reliability and survival analysis in the presence of several causes of failure (competing risks) has attracted attention in the literature. In this paper, series and parallel systems with exponential lifetime for each item of the system are considered. Several causes of failure independently affect lifetime distributions and observations of failure times of the systems are considered under progressive Type-II censored scheme. For series systems, the maximum likelihood estimates of parameters are computed and confidence intervals for parameters of the model are obtained using Fisher information matrix. For parallel systems, the generalized EM algorithm which uses the Newton-Raphson algorithm inside the EM algorithm is used to compute the maximum likelihood estimates of parameters. Also, the standard errors of the maximum likelihood estimates are computed by using the supplemented EM algorithm. The simulation study confirms the good performance of the introduced approach.     

Likelihood ratio order of parallel systems under multiple-outlier models

This paper studies the likelihood ratio ordering of parallel systems under multiple-outlier models. We introduce a partial order, the so-called θ-order, and show that the θ-order between the parameter vectors of the parallel systems implies the likelihood ratio order between the systems.     

基于一种半开式滑槽球副的3-PSP并联平台设计

提出在并联机构中应用一种1移动3转动半开式滑槽球副结构,该运动副将1个移动副和1个球副集成为一个复合的运动副,可以缩短并联机构中支链的尺寸链,有助于提高并联机构精度。基于半开式滑槽球副设计了一种3自由度(3-DOF)PSP三轴并联平台,通过对此机构进行的运动分析和支链的精度分析,导出各个支链的逆解方程,同时根据影响支链运动精度的各个因素给出支链系统误差的线性补偿方程,证明此并联机构具有易于控制、运动精度高的优势。     

交汇契合与并行发展——探寻高等师范教育改革与基础教育改革的共同之路

基础教育与高等师范教育是人才成长的摇篮,而且是教育的两个不同等级的环节.基础教育对中小学生基本素质的形成与知识能力的培养起着不可替代的作用,基础教育质量的提高取决于中小学教师质量的提高;高等师范教育及高等师范院校是学生素质提升与能力提高的关键时期,高等师范教育的目标是为基础教育服务,双方的合作与交流是成功培养人才的需求和必由之路.     

平行志愿背景下地方高校招生宣传策略探讨

文章分析了平行志愿招生办法的实施给地方高校招生及招生宣传工作带来的影响和挑战，并借鉴品牌学、市场营销学的相关策略，对平行志愿背景下如何开展招生宣传、切实增强招生宣传效果等问题作了探讨。     

Computational algorithms for the factor model

Algorithms for computing the maximum likelihood estimators and the estimated covariance matrix of the estimators of the factor model are derived. The algorithms are particularly suitable for large matrices and for samples that give zero estimates of some error variances. A method of constructing estimators for reduced models is presented. The algorithms can also be used for the multivariate errors-in-variables model with known error covariance matrix.     

Graphical methods for comparing confounding in two or more designs

In many circumstances it is necessary to design an experiment with partial confounding of parameter estimates. In this situation, one would like to have tools to assess and compare candidate designs graphically. In this paper we discuss two graphical representations of design properties, and illustrate their application with two examples.     

生命早春里的一缕轻烟——对《小城三月》主人公翠姨的命运分析

萧红是中国现代文学史上一位风格独特的女作家,翠姨是她最后一部作品<小城三月>中的主人公.萧红采用平视叙述视角,使人体会到翠姨之死,一方面是呼兰小城那愚昧、保守的社会环境造成的;另一方面翠姨自身软弱的性格和对男权至上传统道德观念习俗的认同深深毒害了她的思想,这也是她悲剧归宿的深层原因.     

三维有限元渗流模拟计算在蟒河口水库防渗设计中的应用

蟒河口水库工程天然来水量较小，开发目标高，采取有效的防渗处理措施才能保证水库开发要求的蓄水量．工程中采用三维有限元渗流模拟计算对防渗处理措施进行复核．根据计算结果，对防渗措施进行调整、优化，确定了经济、高效的防渗方案．通过工程经验类比知，计算所采用的方法和最终得到的结果是满意的．