Strategic capacity decision‐making in a stochastic manufacturing environment using real‐time approximate dynamic programming

In this study, we illustrate a real‐time approximate dynamic programming (RTADP) method for solving multistage capacity decision problems in a stochastic manufacturing environment, by using an exemplary three‐stage manufacturing system with recycle. The system is a moderate size queuing network, which experiences stochastic variations in demand and product yield. The dynamic capacity decision problem is formulated as a Markov decision process (MDP). The proposed RTADP method starts with a set of heuristics and learns a superior quality solution by interacting with the stochastic system via simulation. The curse‐of‐dimensionality associated with DP methods is alleviated by the adoption of several notions including “evolving set of relevant states,” for which the value function table is built and updated, “adaptive action set” for keeping track of attractive action candidates, and “nonparametric k nearest neighbor averager” for value function approximation. The performance of the learned solution is evaluated against (1) an “ideal” solution derived using a mixed integer programming (MIP) formulation, which assumes full knowledge of future realized values of the stochastic variables (2) a myopic heuristic solution, and (3) a sample path based rolling horizon MIP solution. The policy learned through the RTADP method turned out to be superior to polices of 2 and 3. © 2010 Wiley Periodicals, Inc. Naval Research Logistics 2010     

一类带容量限制的运输问题

考虑一类带容量限制的运输问题.采用构造辅助网络的方法,将运输网络中的每个配送中心均拆分成两个节点,构造出新弧,形成新的网络,把此类运输问题转换为最小费用流问题来解决.并在此基础上,考虑运输网络中配送中心的容量扩张问题.     

后设认知与网络续航——大学古诗词鉴赏课教学策略再探讨

后设认知本为一种学习策略,但其中有关学习调节、学习监督与自我评价等内容,却与课堂教学策略的实施息息相关,可为课堂教学改革提供一定的理论支撑。基于后设认知理论,将学生获取相关网络学习资源的课余任务纳入课堂教学体系,不仅有利于提高学生对古诗词的认知能力,更有益于我们有效地开展大学古诗词的教学改革。     

基于IEEE 802.11的无线多跳网络路径容量分析模型

旨在建立一个适用于无线多跳路径性能研究的闭合分析模型。首先对导致多跳路径中流内竞争现象的干扰问题进行了详细分析并给出了定量计算方法,然后通过将多跳路径建模为排队网络,利用扩散近似法建立了路径性能分析模型,最后在网络稳定性约束条件下对多跳路径的容量问题进行了研究。利用该模型可以在无线多跳网络中分析网络传输的吞吐能力,同时有助于研究网络对QoS业务的支持能力。通过仿真实验结果与数值分析结果的对比,验证了分析模型的准确性。     

舰艇编队综合作战能力评估的模糊聚类分析

评估舰艇编队综合作战能力强弱的模糊聚类分析涉及编队对海作战能力、编队反潜作战能力、编队防空作战能力、编队电子战能力、编队指挥控制能力和编队战场适应能力等因素.以若干舰艇编队为研究对象,对因素指标进行标准量化.据标准化数据用指数相似系数法计算样本间的相似关系,最后根据各样本与基准样本相聚类或分离进行量化分析,判断各舰艇编队综合作战能力的强弱次序.     

新疆兵团土地人口承载力预测分析

随着国家西部大开发战略的实施,新疆生产建设兵团(以下简称兵团)的经济发展速度开始加快,人口增长与兵团资源的矛盾也逐渐凸现,研究兵团人口承载力问题就迫在眉睫。本文以数量经济学的理论和思想为指导,主要采用灰色系统理论、Logistic模型等定量分析方法对兵团人口、经济、资源及可持续发展进行研究。     

Robust capacity planning in semiconductor manufacturing

We present a stochastic programming approach to capacity planning under demand uncertainty in semiconductor manufacturing. Given multiple demand scenarios together with associated probabilities, our aim is to identify a set of tools that is a good compromise for all these scenarios. More precisely, we formulate a mixed‐integer program in which expected value of the unmet demand is minimized subject to capacity and budget constraints. This is a difficult two‐stage stochastic mixed‐integer program which cannot be solved to optimality in a reasonable amount of time. We instead propose a heuristic that can produce near‐optimal solutions. Our heuristic strengthens the linear programming relaxation of the formulation with cutting planes and performs limited enumeration. Analyses of the results in some real‐life situations are also presented. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

Modeling multiple stage manufacturing systems with generalized costs and capacity issues

This study introduces one modeling methodology that describes a broad range of multiple stage production planning issues, including multiple limited resources with setup times and joint fixed cost relationships. An existing production system is modeled in this fashion, creating a new set of 1350 highly generalized benchmark problems. A computational study is conducted with the 1350 benchmark problems introduced in this paper and 2100 benchmark problems, with more restrictive assumptions, from the existing literature. The relative merits of a decomposition‐based algorithm and a neighborhood search technique known as NIPPA, or the Non‐sequential Incremental Part Period Algorithm, are assessed. NIPPA is generally the more successful of the two techniques, although there are specific instances in which the decomposition‐based algorithm displayed a distinct advantage. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

Search and the introduction of improved technologies

Modeling R&D as standard sequential search, we consider a monopolist who can implement a sequence of technological discoveries during the technology search process: he earns revenue on his installed technology while he engages in R&D to find improved technology. What is not standard is that he has a finite number of opportunities to introduce improved technology. We show that his optimal policy is characterized by thresholds ξ_i(x): introduce the newly found technology if and only if it exceeds ξ_i(x) when x is the state of the currently installed technology and i is the number of remaining introductions allowed. We also analyze a nonstationary learning‐by‐doing model in which the monopolist's experience in implementing new technologies imparts increased capability in generating new technologies. Because this nonstationary model is not in the class of monotone stopping problems, a number of surprising results hold and several seemingly obvious properties of the stationary model no longer hold. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

石化企业设置火灾事故应急水池的必要性及容量计算

简要阐述了石化企业设置火灾事故情况下事故应急水池的必要性,并对事故应急水池的计算方法进行分析,最后结合工程实例进行容量计算,对同类的设计提供一定的参考。