Approximation algorithms for capacitated stochastic inventory systems with setup costs

We develop the first approximation algorithm with worst‐case performance guarantee for capacitated stochastic periodic‐review inventory systems with setup costs. The structure of the optimal control policy for such systems is extremely complicated, and indeed, only some partial characterization is available. Thus, finding provably near‐optimal control policies has been an open challenge. In this article, we construct computationally efficient approximate optimal policies for these systems whose demands can be nonstationary and/or correlated over time, and show that these policies have a worst‐case performance guarantee of 4. We demonstrate through extensive numerical studies that the policies empirically perform well, and they are significantly better than the theoretical worst‐case guarantees. We also extend the analyses and results to the case with batch ordering constraints, where the order size has to be an integer multiple of a base load. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 304–319, 2014     

一类分段线性费用网络流问题

本文通过把一类分段线性费用网络流问题化成线性费用网络流问题,给出了求解这类分段线性费用网络流问题的算法。     

Warranty costs: An age‐dependent failure/repair model

An age‐dependent repair model is proposed. The notion of the “calendar age” of the product and the degree of repair are used to define the virtual age of the product. The virtual failure rate function and the virtual hazard function related to the lifetime of the product are discussed. Under a nonhomogeneous Poisson process scenario the expected warranty costs for repairable products associated with linear pro‐rata, nonrenewing free replacement and renewing free replacement warranties are evaluated. Illustration of the results is given by numerical and graphical examples. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

基于遗传算法的目标方位角估算

针对某型武装直升机加装微光电视瞄准系统后 ,提出了采用遗传算法进行微光电视图像的识别和提取 ,然后与模型基元进行图像匹配 ,来研究目标方位角的估算问题。经分析计算 ,能较好地满足需求 ,为微光电视瞄准原理的实现打下一定的基础。     

军用雷达成本波动的源头探索与关键控制

根据军用雷达成本涉及的各个方面,建立雷达成本波动评价指标体系,运用主成分分析法确定其重要影响因子及权重,构造具有望小特性的评价函数可用于竞标决策选优,为军用雷达成本控制提供即时管理。     

基于Tornado码的复制算法

面向Internet的分布存储系统具有数据种类多、数据量大、分布广泛等特点,为了提高分布存储系统的数据访问效率,提出了一种基于Tornado码的复制算法。与传统的复制算法相比,基于Tornado码的复制算法能够提供更高的可用性、持久性和安全性,并且具有更低的存储开销和带宽开销。     

军队院校大学英语课程建设与改革初探

通过对国内大学英语教学改革和课程体系建设相关文献的综述,结合多年来的一线教学经验,客观地反思了军队院校大学英语教学中普遍存在的一些问题,有针对性地探讨了21世纪军队院校大学英语教学改革的总体目标,并对大学英语课程体系的完善提出了一些建设性的措施和设想;还结合新的教学大纲对四级后教学和课程体系建设提出了一些新的见解.     

Optimal control of an M/G/1 queue with impatient priority customers

An optimal operating policy is characterized for the infinite‐horizon average‐cost case of a single server queueing control problem. The server may be turned on at arrival epochs or off at departure epochs. Two classes of customers, each of them arriving according to an independent Poisson processes, are considered. An arriving 1‐customer enters the system if the server is turned on upon his arrival, or if the server is on and idle. In the former case, the 1‐customer is selected for service ahead of those customers waiting in the system; otherwise he leaves the system immediately. 2‐Customers remain in the system until they complete their service requirements. Under a linear cost structure, this paper shows that a stationary optimal policy exists such that either (1) leaves the server on at all times, or (2) turns the server off when the system is empty. In the latter case, we show that the stationary optimal policy is a threshold strategy, this feature being commonplace in most of priority queueing systems and inventory models. However, the optimal policy in our model is determined by two thresholds instead of one. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 201–209, 2001     

基于神经网络的舰船建造费用预测分析

采用了一种基于神经网络的舰船建造费预测方法 .计算结果表明 ,这种方法与传统的参数法相比较 ,有更好的估算精度 ,因而该方法可以作为研究此类问题的新途径     

Optimal (τ, T) opportunistic maintenance of a k‐out‐of‐n:G system with imperfect PM and partial failure

The opportunistic maintenance of a k‐out‐of‐n:G system with imperfect preventive maintenance (PM) is studied in this paper, where partial failure is allowed. In many applications, the optimal maintenance actions for one component often depend on the states of the other components and system reliability requirements. Two new (τ, T) opportunistic maintenance models with the consideration of reliability requirements are proposed. In these two models, only minimal repairs are performed on failed components before time τ and the corrective maintenance (CM) of all failed components are combined with PM of all functioning but deteriorated components after τ; if the system survives to time T without perfect maintenance, it will be subject to PM at time T. Considering maintenance time, asymptotic system cost rate and availability are derived. The results obtained generalize and unify some previous research in this area. Application to aircraft engine maintenance is presented. © 2000 John Wiley & Sons;, Inc. Naval Research Logistics 47: 223–239, 2000