An exact analysis of a joint production‐inventory problem in two‐echelon inventory systems

We consider a two‐echelon inventory system with a manufacturer operating from a warehouse supplying multiple distribution centers (DCs) that satisfy the demand originating from multiple sources. The manufacturer has a finite production capacity and production times are stochastic. Demand from each source follows an independent Poisson process. We assume that the transportation times between the warehouse and DCs may be positive which may require keeping inventory at both the warehouse and DCs. Inventory in both echelons is managed using the base‐stock policy. Each demand source can procure the product from one or more DCs, each incurring a different fulfilment cost. The objective is to determine the optimal base‐stock levels at the warehouse and DCs as well as the assignment of the demand sources to the DCs so that the sum of inventory holding, backlog, and transportation costs is minimized. We obtain a simple equation for finding the optimal base‐stock level at each DC and an upper bound for the optimal base‐stock level at the warehouse. We demonstrate several managerial insights including that the demand from each source is optimally fulfilled entirely from a single distribution center, and as the system's utilization approaches 1, the optimal base‐stock level increases in the transportation time at a rate equal to the demand rate arriving at the DC. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

Allies at arm’s length: Redefining Egyptian–Soviet relations in the 1967 Arab–Israeli war

This article examines Egyptian–Soviet relations in the run up to the 1967 Arab–Israeli war. It argues that Egypt and the Soviet Union stumbled into brinkmanship with little coordination and no agreement on common objectives or goals. The article demonstrates how frustration and mutual disappointment were recurring features of the interactions between the two allies during the critical weeks prior to the war. In doing so, the article exposes new aspects of how Cairo and Moscow managed their alliance and assesses what that means to our understanding of the origins of this transformative war. These conclusions challenge revisionist accounts that attribute the start of the war to Egyptian–Soviet collusion and some traditional narratives that present the Soviet Union as an enterprising risk-taker invested in regional brinkmanship. The article draws heavily on Egyptian and Arabic language sources to examine Egyptian–Soviet interactions during this key period of Middle Eastern history.     

Making long-range planning work: the case of the US Army's 30-year strategic modernization plan

The extensive timespan of evolving assumptions about future adversaries, US military engagements, and technology inherent in the US Army's 30-year modernization strategy can overwhelm the management capacity of planners, and misdirect acquisition investments. Some military scholars have argued that long-range planning is futile due to the complexities of the global security environment. So how can the US Army manage the evolving assumptions inherent in its 30-year modernization strategy to ensure it remains a superior global force? This study will answer the above question by arguing that the US Army's 30-year modernization strategy, while emulative of a similar modernization approach in the threat-based planning environment of the Cold War, is viable if supported by a method and a tool that manage investments and planning assumptions.     

An Ideological Response to Combating Terrorism – The Singapore Perspective

The article examines alternative strategies to combating the scourge of terrorism beyond military approaches. There is now more realization, especially after the difficulties experienced in Iraq today, that an innovative multi-pronged mix of methods is needed to combat international terrorism. The paper looks at an ideological response towards combating terrorism by looking at the Singapore experience. The Singapore government recognizes the importance of an ideological response as an integral part of counterterrorism measures. Terrorism occurs when opportunity, motivation and capability meet. The prevention of terrorism requires the elimination of at least one of these three factors- motivation- often driven by ideology. The paper will look at direct and indirect initiatives undertaken in Singapore to combat terrorism and will also look at the Muslim community in Singapore's response to the threat to Singapore society. Lastly, the article will examine some lessons learnt from the Singapore experience in applying an ideological approach in combating terrorism as well as some recommendations of what more can be done to move forward.     

Relative performance of novel blast wave mitigation system to conventional system based on mitigation percent criteria

Recent researches focused on developing robust blast load mitigation systems due to the threats of terrorist attacks. One of the main embraced strategies is the structural systems that use mitigation techniques. They are developed from a combination of structural elements and described herein as conventional systems. Among the promising techniques is that redirect the waves propagation through hollow tubes. The blast wave propagation through tubes provides an efficient system since it combines many blast wave phenomena, such as reflection, diffraction, and interaction. In this research, a novel blast load mitigation system, employed as a protection fence, is developed using a technique similar to the technique of the bent tube in manipulating the shock-wave. The relative performance of the novel system to the conventional system is evaluated based on mitigation percent criteria. Performances of both systems are calculated through numerical simulation. The proposed novel system proved to satisfy high performance in mitigating the generated blast waves from charges weight up to 500 kg TNT at relatively small standoff distances (5 m and 8 m). It mitigates at least 94％ of the blast waves, which means that only 6％ of that blast impulse is considered as the applied load on the targeted structure.