Operations sequencing for a multi‐stage production inventory system

This article studies operations sequencing for a multi‐stage production inventory system with lead times under predictable (deterministic) yield losses and random demand. We consider various cases with either full or partial release of work‐in‐process inventories, for either pre‐operation or post‐operation cost structures, and under either the total discounted or average cost criteria. We derive necessary and sufficient criteria for the optimal sequence of operations in all cases. While the criteria differ in their specific forms, they all lead to the same principal: those operations with (1) lower yields, (2) lower processing costs, (3) longer lead times, and (4) lower inventory holding costs should be placed higher upstream in the system.Copyright © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 144–154, 2014     

Lessons learnt? Cultural transfer and revolutionary wars, 1775–1831

Did participants in small wars in the period 1775–1831 learn from previous or contemporary examples? While this is difficult to prove for participants who left no written records, there is considerable evidence in existing publications by practitioners that they did indeed draw out lessons from recent insurgencies, either from their own experience or from events elsewhere which they studied from afar, especially the Spanish Guerrilla, which had already become legendary. Most authors showed an interest in how to stage insurgencies rather than in how to quell them. Even then, transfer did not come in a package of tactics-cum-values, but in each case in different configurations.     

船舶电力系统模拟训练评估算法

针对船舶电力模拟训练评估系统的设计与实现问题,分析了构建指标体系的方法。依据设计原则,设计了船舶电力模拟训练的评估指标体系。确定了各评估指标的算法,并根据层次分析法构建权重集,然后运用模糊评判理论建立了综合评估模型。选取某船电力系统模拟训练考核的实例,进行了考核和综合评估,结果表明:该方法科学,可操作性强。     

可修复型备件满足率的适用方案研究

在离散状态空间的马尔科夫过程的基础上,对可修复型备件满足率模型进行了研究,分析了经典的保障概率模型在装备综合保障过程中所存在的弊端,在增加备件维修次数阈值条件的基础上对模型进行改进后得到了一种新的可修复型备件满足率模型。在备件数量较少(等于1时)的情况下,与经典模型对比,该模型的符合程度较好;当备件数量较多时(大于1时),设计了在ExtendSim仿真软件环境下的仿真模型,并用仿真模型来检验改进后备件满足率模型的正确性,通过对比分析表明:该改进的备件满足率模型能较好地评估可修复型备件满足率指标,相比经典模型和仿真模型,避免了复杂耗时的运算过程,能够方便而且高效地运用于装备综合保障任务当中。     

Conjectures for framing cyberwarfare

Cyberspace has emerged as a potentially new (and unconventional) domain for warfare. Much debate has focused on understanding cyber conflict. The ability to critically analyse this phenomenon is important; however, the nascent nature of cyberwarfare and the complexity of the systems involved create challenges not met by conventional approaches. As a first step, this requires an analytical construct to frame discussions in a way that highlights distinct characteristics of the cyber domain. An approach proposed is one of the postulating conjectures for debate as a way to achieve this and to demonstrate its use, both at the strategic and operational levels. It is suggested that such an approach provides one component of a mature analytical framework for the analysis of cyber across a range of warfare domains.     

Complexity and workload considerations in product mix decisions under the theory of constraints

The literature on the product mix decision (or master production scheduling) under the Theory of Constraints (TOC), which was developed in the past two decades, has addressed this problem as a static operational decision. Consequently, the developed solution techniques do not consider the system's dynamism and the associated challenges arising from the complexity of operations during the implementation of master production schedules. This paper aims to address this gap by developing a new heuristic approach for master production scheduling under the TOC philosophy that considers the main operational factors that influence actual throughput after implementation of the detailed schedule. We examine the validity of the proposed heuristic by comparison to Integer Linear Programming and two heuristics in a wide range of scenarios using simulation modelling. Statistical analyses indicate that the new algorithm leads to significantly enhanced performance during implementation for problems with setup times. The findings show that the bottleneck identification approach in current methods in the TOC literature is not effective and accurate for complex operations in real‐world job shop systems. This study contributes to the literature on master production scheduling and product mix decisions by enhancing the likelihood of achieving anticipated throughput during the implementation of the detailed schedule. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 357–369, 2015     

Selling to strategic and loss‐averse consumers: Stocking,procurement, and product design policies

Motivated by the presence of loss‐averse decision making behavior in practice, this article considers a supply chain consisting of a firm and strategic consumers who possess an S‐shaped loss‐averse utility function. In the model, consumers decide the purchase timing and the firm chooses the inventory level. We find that the loss‐averse consumers' strategic purchasing behavior is determined by their perceived gain and loss from strategic purchase delay, and the given rationing risk. Thus, the firm that is cognizant of this property tailors its inventory stocking policy based on the consumers' loss‐averse behavior such as their perceived values of gain and loss, and their sensitivity to them. We also demonstrate that the firm's equilibrium inventory stocking policy reflects both the economic logic of the traditional newsvendor inventory model, and the loss‐averse behavior of consumers. The equilibrium order quantity is significantly different from those derived from models that assume that the consumers are risk neutral and homogeneous in their valuations. We show that the firm that ignores strategic consumer's loss‐aversion behavior tends to keep an unnecessarily high inventory level that leads to excessive leftovers. Our numerical experiments further reveal that in some extreme cases the firm that ignores strategic consumer's loss‐aversion behavior generates almost 92% more leftovers than the firm that possesses consumers’ loss‐aversion information and takes it into account when making managerial decisions. To mitigate the consumer's forward‐looking behavior, we propose the adoption of the practice of agile supply chain management, which possesses the following attributes: (i) procuring inventory after observing real‐time demand information, (ii) enhanced design (which maintains the current production mix but improves the product performance to a higher level), and (iii) customized design (which maintains the current performance level but increases the variety of the current production line to meet consumers’ specific demands). We show that such a practice can induce the consumer to make early purchases by increasing their rationing risk, increasing the product value, or diversifying the product line. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 435–453, 2015     

GNSS/INS超紧组合导航综述

卫星/惯性超紧组合导航系统以其定位精度高、动态性能优良、抗干扰能力强等特性成为组合导航领域的研究热点。介绍了卫星/惯性超紧组合的定位原理,基于对技术原理的分析,比较超紧组合模式相对于其他组合模式的优势特点;以高动态下超紧组合技术及卫星/微惯性单元超紧组合为代表介绍国内外研究现状;总结了亟待研究的容错控制技术、神经网络辅助、多传感器辅助超紧组合等关键技术,并对卫星/惯性超紧组合向着低成本、高精度、强稳定趋势发展的前景进行展望。     

基于Petri网的综合电子系统总线建模与性能优化

针对综合电子系统运用中总线效率不高等问题,以某型步兵战车综合电子系统为例,通过对系统进行信息流规划,结合总线协议和实现机制,采用赋时颜色Petri网对综合电子信息系统通信机制进行建模,实现综合电子系统总线通信协议机制的仿真。通过对系统总线性能指标参数的分析,提出综合电子信息系统总线的优化方案。关键词：赋时颜色Petri网;综合电子系统;总线建模;性能优化     

Revenue management: A real options approach

Revenue management is the process of actively managing inventory or capacity to maximize revenues. The active management typically occurs through managerial levers such as price, promotion, or availability. We present a novel real options approach to revenue management that is specifically suited to the car rental business. We illustrate the concept with actual car rental data. The model produces minimally acceptable prices and inventory release quantities (number of cars available for rent at a given price) as a function of remaining time and available inventory. The pricing and inventory release recommendations of the developed model confirm earlier empirical analysis that suggested current practises discount too deeply early in the booking cycle. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004