A Non-parametric Frailty Model for Temporally Clustered Multivariate Failure Times

Abstract A model is introduced here for multivariate failure time data arising from heterogenous populations. In particular, we consider a situation in which the failure times of individual subjects are often temporally clustered, so that many failures occur during a relatively short age interval. The clustering is modelled by assuming that the subjects can be divided into ‘internally homogenous’ latent classes, each such class being then described by a time‐dependent frailty profile function. As an example, we reanalysed the dental caries data presented earlier in Härkänen et al. [Scand. J. Statist. 27 (2000) 577], as it turned out that our earlier model could not adequately describe the observed clustering.     

基于TOPSIS理论的企业供应商选择应用

供应链管理已经成为企业获取竞争优势的手段,供应商选择是企业构建供应链体系的重要内容。TOPSIS是一种简单易行的多因素选优的理论方法,它利用熵来确定评价指标的权重,避免了在确定评价指标权重时主观因素的影响,为公司的供应商选择提供了一种科学、量化、高效的手段。文章回顾了供应商选择的理论现状,介绍了TOPSIS理论模型和利用它进行供应商选择的步骤,通过对典型企业的深入调研,阐述了该企业如何应用TOPSIS进行供应商选择。     

附加价值链与企业长程发展

企业附加价值链表征企业文化的浓缩 ,是企业发展的生命线。企业附加价值链清晰、完备与否 ,是剖析企业存在、发展的根本之所在 ,也是考查、评价企业现状的基本依据。     

略论邓小平理论萌芽的界定及其标志

作为邓小平理论萌芽的标志不是某一具体的时间、论著、观点。对邓小平理论萌芽应作出系统的、全面的科学界定。邓小平理论萌芽的标志应该是时间段、论著链、观点网     

A Unified Approach to the Characterization of Equivalence Classes of DAGs, Chain Graphs with no Flags and Chain Graphs

Abstract.  A Markov property associates a set of conditional independencies to a graph. Two alternative Markov properties are available for chain graphs (CGs), the Lauritzen–Wermuth–Frydenberg (LWF) and the Andersson–Madigan– Perlman (AMP) Markov properties, which are different in general but coincide for the subclass of CGs with no flags . Markov equivalence induces a partition of the class of CGs into equivalence classes and every equivalence class contains a, possibly empty, subclass of CGs with no flags itself containing a, possibly empty, subclass of directed acyclic graphs (DAGs). LWF-Markov equivalence classes of CGs can be naturally characterized by means of the so-called largest CGs , whereas a graphical characterization of equivalence classes of DAGs is provided by the essential graphs . In this paper, we show the existence of largest CGs with no flags that provide a natural characterization of equivalence classes of CGs of this kind, with respect to both the LWF- and the AMP-Markov properties. We propose a procedure for the construction of the largest CGs, the largest CGs with no flags and the essential graphs, thereby providing a unified approach to the problem. As by-products we obtain a characterization of graphs that are largest CGs with no flags and an alternative characterization of graphs which are largest CGs. Furthermore, a known characterization of the essential graphs is shown to be a special case of our more general framework. The three graphical characterizations have a common structure: they use two versions of a locally verifiable graphical rule. Moreover, in case of DAGs, an immediate comparison of three characterizing graphs is possible.     

汽车行业电子商务与供应链一体化集成分析

在研究了我国汽车行业供应链存在诸多不容忽视问题的基础上,提出了汽车行业实施电子商务与供应链一体化集成的管理学思想,分析了汽车行业实施电子商务与供应链一体化集成的技术、管理和经济三大主导驱动力量,构建了电子商务与汽车行业供应链进行一体化集成结构模型,并对汽车行业供应链一体化集成的具体功能模块进行了概要描述。     

构建研产销供应链促进高科技企业的发展

加入WTO对我国高科技企业来说是更大的挑战。本文讨论的是用供应链管理的思想来推进高新技术产业的发展。以高科技企业为核心构建或以高新技术改造供应链 ,促进科研成果的转化 ,增强核心企业的竞争力。从强化核心竞争力、战略联盟、信息技术等方面提出了构建研产销供应链的方法。     

丰水区筑坝截流——调丰补歉

该文从中国人口快速增长、经济建设加快、用水量逐年增大 ,加上气候变暖、少雨干旱将持续到 2 0 15年 ,我国北方水生态环境日趋恶化现状 ,说明在丰水区筑坝截流、调丰补歉势在必行 ,完全符合生态经济学发展原则和国际水法     

农户借款的供求约束及解除

我国的农村金融改革一直是政府导向的,包括现在进行的农村信用社改革。农村金融改革应充分考虑到农村经济主体对资金的需求特征,只有这样,才不致于出现供给缺位和需求得不到满足的情况。因此,研究我国农村中最大的经济主体———农户与正规金融机构之间的借款行为,通过对借贷双     

供应链物流系统运作模式分析

现代物流是以基于市场需求有效提供商品的供给系统为中心,通过供应链不同职能部门之间或不同企业之间的信息共享、协同发展、共同规划,而形成的完整、连续的供应链一体化运作流程。在供应链物流系统中,物流功能不断整合优化,系统运行模式也不断变化。企业可以通过投机延迟原理的有机结合,进行供应链分离点的科学定位,形成物资从企业到市场的最佳流动路线,实现最优的供应链物流。