Accurate computation of single and product moments of order statistics under progressive censoring

An accurate procedure is proposed to calculate approximate moments of progressive order statistics in the context of statistical inference for lifetime models. The study analyses the performance of power series expansion to approximate the moments for location and scale distributions with high precision and smaller deviations with respect to the exact values. A comparative analysis between exact and approximate methods is shown using some tables and figures. The different approximations are applied in two situations. First, we consider the problem of computing the large sample variance–covariance matrix of maximum likelihood estimators. We also use the approximations to obtain progressively censored sampling plans for log-normal distributed data. These problems illustrate that the presented procedure is highly useful to compute the moments with precision for numerous censoring patterns and, in many cases, is the only valid method because the exact calculation may not be applicable.     

Progressive censoring with fixed censoring times

In this paper, we revisit the progressive Type-I censoring scheme as it has originally been introduced by Cohen [Progressively censored samples in life testing. Technometrics. 1963;5(3):327–339]. In fact, original progressive Type-I censoring proceeds as progressive Type-II censoring but with fixed censoring times instead of failure time based censoring times. Apparently, a time truncation has been added to this censoring scheme by interpreting the final censoring time as a termination time. Therefore, not much work has been done on Cohens's original progressive censoring scheme with fixed censoring times. Thus, we discuss distributional results for this scheme and establish exact distributional results in likelihood inference for exponentially distributed lifetimes. In particular, we obtain the exact distribution of the maximum likelihood estimator (MLE). Further, the stochastic monotonicity of the MLE is verified in order to construct exact confidence intervals for both the scale parameter and the reliability.     

Inference and optimal design of multiple constant-stress testing for generalized half-normal distribution under type-II progressive censoring

The generalized half-normal (GHN) distribution and progressive type-II censoring are considered in this article for studying some statistical inferences of constant-stress accelerated life testing. The EM algorithm is considered to calculate the maximum likelihood estimates. Fisher information matrix is formed depending on the missing information law and it is utilized for structuring the asymptomatic confidence intervals. Further, interval estimation is discussed through bootstrap intervals. The Tierney and Kadane method, importance sampling procedure and Metropolis-Hastings algorithm are utilized to compute Bayesian estimates. Furthermore, predictive estimates for censored data and the related prediction intervals are obtained. We consider three optimality criteria to find out the optimal stress level. A real data set is used to illustrate the importance of GHN distribution as an alternative lifetime model for well-known distributions. Finally, a simulation study is provided with discussion.     

站在人类先进文化发展的潮头

该文以唯物史观为指导,阐明了马克思主义文化理论、中国现代文化的形成和中国先进文化的发展方向.作者认为文化是人类社会在经济、政治、精神上的反映,包括意识形态和其他一切精神活动及其产物,对经济、政治又具有强大的反作用.中国现代社会主义文化是由农业封建主义文化在近百年的经济、政治发展的基础上逐渐演变而成的,它的前进方向是面向现代化、面向世界、面向未来的民族的、科学的、大众的社会主义文化.     

我国高校文科学报的“当代化”论

高校文科学报的“当代化”是相对于时下盛行的“现代化”而言的。它是根据我国高校文科学报的发生及其发展历程的阶段性特征 ,以及“当代化”所蕴涵的人类文明进程的阶段性定位和“与时俱进”的时代性体现的科学内涵而提出来的。“当代化”具有现实性和求真性的鲜明特征 ,对于 2 1世纪我国高校文科学报的发展是一种求真务实的选择。     

用发展先进文化的理论指导高校文科学报创新

高校文科学报在高校不断深化改革的新形势下 ,应与时俱进 ,开拓创新。发展先进文化的理论对高校文科学报的创新有着重要的指导作用。只有认真学习 ,深刻领会 ,结合实际 ,准确定位 ,才能更好地用发展先进文化的思想和理论来指导高校文科学报的创新     

高校学报影响因子评析

2001年中国科技论文统计源期刊中,高校学报的影响因子为0.140,低于统计源期刊影响因子平均值0.264,也大大低于国际期刊.高校学报影响因子的影响因素有出版时滞因素、检索系统因素、学科因素、语种因素、政策导向因素和科技水平因素等.影响因子是评价学报质量的重要指标,但不是唯一的衡量指标.提高学报影响因子的措施有组约优质稿件,注意政策导向,减少出版时滞,降低语种影响和调整学报结构.     

高校合并对原医学院校学报的影响

高校合并将给合并前的原医学院校学报(以下简称学报)带来提高学术水平、扩大刊物影响力、增加稿源和扩展作者群的机会,但短期内学报刊名变更可能会影响检索系统数据库对其文献计量学参数的统计,也可能影响刊物的订阅.学报应抓住机遇,努力克服短期内的不利因素,不断提高刊载论文的学术水平,使学报越办越好.     

理工农医高校文科学报发展的制约因素

与那些重点综合性大学和师范类高校的文科学报相比,理工农医院校的文科学报存在诸多的发展制约因素:学报发展缺乏强势学科的支撑;学报的稿源不够理想;学校对学报重视不够,编辑人员的结构不够合理;办刊模式僵化,缺少个性和特色。理工农医高校文科学报要突破各种阻碍学报发展的制约因素,就要更新观念,大胆变革,锐意创新,不断探索期刊发展的新路。