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。     

基于遗传算法的装备采购决策优化研究

在装备采购中，由于需求单位地域分布和担负的任务各不相同，对装备的品种、数量、时限要求也就不一样，如何使装备采购科学化、合理化，是一个涉及多变量、多目标的复杂系统问题。在综合考虑装备采购各项因素的基础上，构建多约束条件下的多目标模糊指派模型，提出了基于遗传算法的解决方案，最后通过案例进行仿真实验，验证该算法的可行性和有效性，解决了采用传统优化方法难以解决的装备采购优化决策问题。     

集中优势发展重庆电子信息产业

在分析重庆市电子信息设备制造业现状、发展的有利与不利因素以及国内外发展态势的基础上对重庆(?)子信息产业的发展提出了九条对策建议。     

装备工业的快速发展与产业结构的优化升级

落后的技术装备水平是导致我国工业粗放型增长并进而导致结构性矛盾的重要原因。在新的发展阶段 ,优化产业结构 ,淘汰落后技术 ,全面更新技术手段和生产设备 ,加快装备工业发展 ,推进关键设备国产化 ,成为提高国民经济运行质量和效益的战略性环节     

听力课与视听课相结合的新模式

学校原有的语言实验室、视听实验室各有局限，已不能满足教学需要。因此，对两个实验室的两套设备进行具体的技术改造，组建成了一个新的功能更加完善的语言与视听实验室，从而大大提高了听力与视听课的教学质量。     

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.     

低温外科手术器械的现状和展望

本文从工程应用角度出发,综述了目前使用的各种低温外科手术器械的性能特点和适用场合。以当前使用最普遍的LN_2式冷疗仪为例对其原理、结构作了简要说明,着重指出其制造的关键和存在的不足,并对冷疗仪的进一步发展作了展望。     

层次分析法在成套设备招标评标中的应用

介绍层次分析法的择优原理及其在成套设备招标评标中的应用;给出计算机软件包,以克服层次分析法计算量过大的缺点。