Optimal scheduling replacement policies for a system with multiple random works

From the economical viewpoint in reliability theory, this paper addresses a scheduling replacement problem for a single operating system which works at random times for multiple jobs. The system is subject to stochastic failure which results the imperfect maintenance activity based on some random failure mechanism: minimal repair due to type-I (repairable) failure, or corrective replacement due to type-II (non-repairable) failure. Three scheduling models for the system with multiple jobs are considered: a single work, N tandem works, and N parallel works. To control the deterioration process, the preventive replacement is planned to undergo at a scheduling time T or the job's completion time of for each model. The objective is to determine the optimal scheduling parameters (T^* or N^*) that minimizes the mean cost rate function in a finite time horizon for each model. A numerical example is provided to illustrate the proposed analytical model. Because the framework and analysis are general, the proposed models extend several existing results.     

社会转型与观念变迁--以“道德缺失”为中心的考察

尽管“道德缺失”是转型期中国一个不容忽视的社会问题，但当代的“道德缺失”现象并非严重到了危机阶段，中国古代也不是“道德天堂”。今天的道德困境可以归因于社会环境的巨大变化。这种问题的解决，需依靠有效的维护机制作为保障。落实到根本，还是要大力发展经济，建设市民社会。     

多校区图书馆的典藏工作

高校合并后,许多院校的图书馆都出现了多校区、多分馆的管理局面。笔者从新图书典藏、调拨、剔除几个方面简要论述了如何搞好多校区图书馆的典藏工作。     

Some remarks on the physical models concerning two different approaches to inference in statistical process control

Summary For technological applications it can be useful to identify some simple physical mechanisms, which, on the basis of the available knowledge of the production process, may suggest the most appropriate approach to statistical control of the random quantities of interest. For this purpose the notion of rupture point is introduced firstly. A rupture point is characterized bym randomly arising out of control states, assumed to be mutually exclusive and stochastically independent. Shewhart's control charts seem to represent the natural statistical tool for controlling a rupture point; however it is shown that they are fully justified only when the hazard rates attached to the causes of failure are constant. Otherwise, typically in the presence of time increasing hazard rates, Shewhart's control charts should be completed by a preventive intervention rule (preventive maintenance). In the second place, the notion of dynamic instability point is introduced, which is specifically characterized by assuming that the random quantity of interest is ruled by a stochastic differential equation with constant coefficients. By discretization, developed according to a possibly new approach, it is shown that the former model reduces to an equation error model, which is among the simplest used in adaptive control, and thus particularly easy to deal with in regard to parameter estimation and the definition of the optimum control rule.     

科技特派员制度生命力的探析

地处闽北的南平市在发展当地经济、促进农业重大转型的特定时期,启动科技特派员制度,有其深刻的时代背景和现实意义。本文从科技特派员制度创举与活力切入,分析这一制度创举深层次的原因,并进一步探讨这一制度生命力如何在新时期持续和创新。     

基于马尔可夫链的产品市场保有量预测模型

售后服务机构为了准确地准备库存,都需要预测产品的市场保有量。基于马尔可夫链建立的状态概率矩阵模型,与抽样调查、时间序列法、回归分析法等方法相比,更能准确预测市场产品保有量。与传统产品相比较,更新换代速度快的电子产品,要预测其市场保有量,更需要利用状态概率矩阵模型。     

紧贴行业的应用型人才培养模式之研究

广东白云学院在推进汽车检测与维修技术专业教学改革过程中,紧紧围绕汽车服务业的现状和特点,以行业人才需求为依据,确定专业培养目标和人才规格,以行业的岗位能力要求为出发点,构建高效、实用的培养方案,以服务于行业为目标,建立有行业参与的教学机制,在人才培养质量上取得了优异的成绩。     

60Co-r射线辐射保持系嘉浙B的M2代突变类型分析

用60 CO-r射线直接辐射保持系嘉浙B诱发突变 ,M2 代出现多种变异 ,按变异频率大小从高到底依次为 :叶色突变>早熟突变 >颖尖不退花突变 >高外露率突变 >薄颖壳突变 >花时早 >突变紫稃尖突变 >迟熟突变 ,上述 8个选择项的总突变频率达到 2 .4 19% ,说明辐射诱变改良保持系性状十分有效     

Poverty and social trends in Russia

The article describes the socioeconomic situation of the Russian population and its dynamics in 1992. The analysis is based on series of regional sociological surveys led by the All-Russian Living Standards Research Center and on official Russian statistical data. The basic unit of analysis is the family, and hence family typology approbated both in research and in practical social work is introduced. Besides describing and discussing the growing poverty tendencies in contemporary Russia, the article also contains methodological recommendations for social policy bodies and social workers on the strategy of work in social maintenance and social support of the least secure population strata.