Distributions of simple patterns in some kinds of exchangeable sequences

In this article, we consider the distributions of simple patterns in some types of sequences of infinite exchangeable multi-state trials. The distributions on exchangeable multi-state trials are considered in terms of an extension of de Finetti's theorem. As an application of partially exchangeable sequences, distributions on a Markov exchangeable sequence are studied. Furthermore, we propose a new type of partially exchangeable sequence and examine its properties. In addition, we discuss the distribution theory in the case of the finite exchangeable sequences. The results presented here provide a wide framework for developing the exact distribution theory of simple patterns. Finally, some examples are given in order to illustrate our theoretical results.     

具有隐藏故障的多状态竞争失效系统检测策略研究

复杂工业系统的故障中有40%属于隐藏故障,若隐藏故障得不到及时消除,则可能导致巨大的经济损失。本文针对具有隐藏故障的多状态竞争失效系统,在考虑不完全检测的基础上,对其进行了维修建模。首先,基于制定的视情维修策略,分析了系统的更新情形;然后,基于所推导出的各种系统更新情形的发生概率,建立了以期望成本率为目标函数,以检测间隔时间为决策变量的维修模型。最后,以电容器组为例对所构建维修模型的适用性和有效性进行了验证,研究结果表明,检测质量对检测策略的制定有重要影响,因此研究具有隐藏故障的多状态竞争失效系统的检测策略时,有必要考虑检测误差。本文提出的维修建模方法不仅能在一定程度上丰富多状态竞争失效系统的维修策略理论与方法,还能为工程实际中复杂工业系统的维修工作提供理论基础与决策依据。     

Multi-state Models in Epidemiology

I first discuss the main assumptions which can be made for multi-state models: the time-homogeneity and semi-Markov assumptions, the problem of choice of the time scale, the assumption of homogeneity of the population and also assumptions about the way the observations are incomplete, leading to truncation and censoring. The influence of covariates and different durations and time-dependent variables are synthesized using explanatory processes, and a general additive model for transition intensities presented. Different inference approaches, including penalized likelihood, are considered. Finally three examples of application in epidemiology are presented and some references to other works are given.     

Network reliability for multipath TCP networks with a retransmission mechanism under the time constraint

It is essential to reduce data latency and guarantee quality of service for modern computer networks. The emerging networking protocol, Multipath Transmission Control Protocol, can reduce data latency by transmitting data through multiple minimal paths (MPs) and ensure data integrity by the packets retransmission mechanism. The bandwidth of each edge can be considered as multi-state in computer networks because different situations, such as failures, partial failures and maintenance, exist. We evaluate network reliability for a multi-state retransmission flow network through which the data can be successfully transmitted by means of multiple MPs under the time constraint. By generating all minimal bandwidth patterns, the proposed algorithm can satisfy these requirements to calculate network reliability. An example and a practical case of the Pan-European Research and Education Network are applied to demonstrate the proposed algorithm.     

多维度失能测度指标体系构建及失能分级研究

以ICF理论框架的交互影响理念为依据,从多维度视角构建了失能测度指标体系。首先,通过赋值法,得到多维度下的失能总分,依据得分将其划分为重度失能、偏重度失能、中度失能、轻度失能及健康五种功能状态,构造死亡概率模型及失能状态转移概率模型,结果显示,失能分级标准是可靠的。其次,利用CLHLS数据库2011年及2014年追踪调查数据,通过构造多状态转移概率矩阵,实证测算了多状态失能转移概率;借助第六次全国人口普查数据,估算了中国65岁及以上失能人口规模、各状态维持时间及预期寿命等。结果显示,初始健康的老人三年期转移概率维持在健康的概率最高,其死亡率也最低;而初始状态为重度失能的老人死亡率最高,其维持重度失能及转移到偏重度等失能状态的概率也最高。研究结论表明,直接依据数据的失能状态转移概率测算比建模估计要准确;基于多状态转移概率矩阵评估的失能规模、预期寿命等均比已有分级测度结果可靠性更高。