A Markovian model for process setup and improvement

We examine the setup and improvement policies for a production process with multiple performance states. Assume that the production process deteriorates randomly over time, following a Markovian process with known transition probabilities. In order to reduce the production cost incurred because of process deterioration, the process is inspected at the end of each period. Then one of three actions may be taken: do nothing, perform routine process setup, or perform routine setup and process improvement. The routine setup operation returns the process to its best performance state, whereas the process improvement action may reduce future production and setup costs and improve the process-state transition probabilities. A discounted Markovian model is formulated to find the strategy that minimizes the total cost of operating the production process. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 383–400, 1997     

Planning accelerated life tests for censored two‐parameter exponential distributions

We consider optimal test plans involving life distributions with failure‐free life, i.e., where there is an unknown threshold parameter below which no failure will occur. These distributions do not satisfy the regularity conditions and thus the usual approach of using the Fisher information matrix to obtain an optimal accelerated life testing (ALT) plan cannot be applied. In this paper, we assume that lifetime follows a two‐parameter exponential distribution and the stress‐life relationship is given by the inverse power law model. Near‐optimal test plans for constant‐stress ALT under both failure‐censoring and time‐censoring are obtained. We first obtain unbiased estimates for the parameters and give the approximate variance of these estimates for both failure‐censored and time‐censored data. Using these results, the variance for the approximate unbiased estimate of a percentile at a design stress is computed and then minimized to produce the near‐optimal plan. Finally, a numerical example is presented together with simulation results to study the accuracy of the approximate variance given by the proposed plan and show that it outperforms the equal‐allocation plan. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 169–186, 1999     

A note on parallel machine replacement

Jones, Zydiak, and Hopp [1] consider the parallel machine replacement problem (PMRP), in which there are both fixed and variable costs associated with replacing machines. Increasing maintenance cost motivates replacements, and a fixed replacement cost provides incentive for replacing machines of the same age in clusters. They prove two intuitive but important results for finite- or infinite-horizon PMRPs, which significantly reduce the size of the linear programming (LP) formulation of the problem and computing efforts required to obtain an optimal replacement policy. Their results are the no-splitting rule (NSR) and the older cluster replacement rule (OCRR). Under a slightly weaker set of assumptions, we prove a third rule, the all-or-none rule (AONR), which states that in any period, an optimal policy is to keep or to replace all the machines regardless of age. This result further reduces the size of the LP formulation of the PMRP. © 1993 John Wiley & Sons, Inc.     

Design of a two-stage screening procedure using correlated variables: A loss function approach

Because of the rapid growth in automated manufacturing systems, complete inspection (screening) becomes very attractive. Sophisticated automated inspection equipment can efficiently process a large number of items and produce consistent and accurate results. However, in many applications the performance variable of interest is expensive to measure even by using automated inspection equipment. One alternative to deal with this problem is to use another variable, which is correlated with the performance variable and relatively inexpensive to measure as the screening variable. Since a screening variable is not perfectly correlated with the performance variable, decision errors that reject good-quality items or accept poor-quality items may occur. To reduce these errors, we propose a two-stage screening procedure in which the first-stage screening is based on a screening variable and the second-stage screening is based on the performance variable. The second-stage screening is performed only on those items of which the disposition cannot clearly be determined by the result of first stage screening. Three losses are considered in the formulation of the model. The first loss is the cost of inspection, the second loss is the cost associated with the disposition of rejected items, and the third loss is incurred by imperfect quality of accepted items. The optimal solution is derived and compared to the single-stage screening procedures based on the screening variable and the performance variable. In addition, the sensitivity of the optimal screening procedure with respect to the correlation between the performance variable and the screening variable and the cost of inspecting the performance variable is discussed and demonstrated by numerical results.     

中世纪外国军事思想初探

军事思想是人们对战争、军队和国防的基本问题的理性认识。研究和总结人类各个时期军事思想的历史发展和特点,是对军事领域问题探讨的过程之一,是人类在军事领域自我认知的手段和途径,是超越自我、实现突破的必经之路。中世纪世界军事思想在特定的历史条件下.经历了一个缓慢的历史演变过程,其战争观、军队建设和战略战术思想有了较大的发展,呈现出缓慢性、演进性和多元性的特征。     

新民主主义革命时期我军军事行政法制建设的历史演进之考察

我军军事行政法制建设是和人民军队的建立和发展紧密联系在一起的。新民主主义革命时期,我军的军事行政法制建设随着革命形势的发展而不断变化调整,为新民主主义和社会主义军事行政法制建设奠定了基础,开辟了道路,在中国军事行政法制史上占有重要的地位,在我军乃至我国的法制建设史上留下了光辉的一页。     

战车火控系统软件可靠性的仿真测试平台

以平均无故障时间间隔(MTBF)和任务成功率为主指标,以某型坦克火控系统为载体,提出了战车非制导武器火控系统软件可靠性仿真测试平台的方案,并对其软件可靠性的仿真测试与验证技术进行了讨论.     

Force chains based mesoscale simulation on the dynamic response of Al-PTFE granular composites

Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminum-polytetrafluoroethylene (Al-PTFE) granular composites under a low-velocity impact. A two-dimensional model followed the randomly normal distribution of real Al particles size is developed. The dynamic compressive process of Al-PTFE composites with varied Al mass fraction is simulated and validated against the experiments. The results indicate that, force chains behavior governed by the number and the size of agglomerated Al particles, significantly affects the impact response of the material. The failure mode of the material evolves from shear failure of matrix to debonding failure of particles with increasing density. A high crack area of the material is critical mechanism to arouse the initiation re-action. The damage maintained by force chains during large plastic strain builds up more local stresses concentration to enhance a possible reaction performance. In addition, simulation is performed with identical mass fraction but various Al size distribution to explore the effects of size centralization and dispersion on the mechanical properties of materials. It is found that smaller sized Al particle of com-posites are more preferred than its bulky material in ultimate strength. Increasing dispersed degree is facilitated to create stable force chains in samples with comparable particle number. The simulation studies provide further insights into the plastic deformation, failure mechanism, and possible energy release capacity for Al-PTFE composites, which is helpful for further design and application of reactive materials.     

基于专家系统的防化保障预案评估研究

人工智能技术在众多领域获得广泛应用．为满足现代战争对防化指挥手段的现代化要求,针对不易量化的防化指挥决策问题的评估,提出了构建知识库并应用模糊推理机制建立专家系统,据此进行防化保障预案的评估选优方法,并对该方法的求解过程进行了探讨．     

加强军队全面建设是党执政的一项重大战略任务--学习《中共中央关于加强党的执政能力建设的决定》

<中共中央关于加强党的执政能力建设的决定>指出,坚持国防建设与经济建设协调发展,建设一支现代化、正规化的革命军队,是党执政的一项重大战略任务.坚持党对军队的绝对领导,加强军队全面建设,既是对我们党取得执政经验的科学总结,又是巩固我们党执政地位的现实保障,同时,加强军队全面建设对提高我们党的执政能力还具有服务和促进的功能.