Optimal capacity in a coordinated supply chain

We consider a supply chain in which a retailer faces a stochastic demand, incurs backorder and inventory holding costs and uses a periodic review system to place orders from a manufacturer. The manufacturer must fill the entire order. The manufacturer incurs costs of overtime and undertime if the order deviates from the planned production capacity. We determine the optimal capacity for the manufacturer in case there is no coordination with the retailer as well as in case there is full coordination with the retailer. When there is no coordination the optimal capacity for the manufacturer is found by solving a newsvendor problem. When there is coordination, we present a dynamic programming formulation and establish that the optimal ordering policy for the retailer is characterized by two parameters. The optimal coordinated capacity for the manufacturer can then be obtained by solving a nonlinear programming problem. We present an efficient exact algorithm and a heuristic algorithm for computing the manufacturer's capacity. We discuss the impact of coordination on the supply chain cost as well as on the manufacturer's capacity. We also identify the situations in which coordination is most beneficial. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Modeling and analysis of multiobjective lot splitting for N‐product M‐machine flowshop lines

Lot splitting is a new approach for improving productivity by dividing production lots into sublots. This approach enables accelerating production flow, reducing lead‐time and increasing the utilization of organization resources. Most of the lot splitting models in the literature have addressed a single objective problem, usually the makespan or flowtime objectives. Simultaneous minimization of these two objectives has rarely been addressed in the literature despite of its high relevancy to most industrial environments. This work aims at solving a multiobjective lot splitting problem for multiple products in a flowshop environment. Tight mixed‐integer linear programming (MILP) formulations for minimizing the makespan and flowtime are presented. Then, the MinMax solution, which takes both objectives into consideration, is defined and suggested as an alternative objective. By solving the MILP model, it was found that minimizing one objective results in an average loss of about 15% in the other objective. The MinMax solution, on the other hand, results in an average loss of 4.6% from the furthest objective and 2.5% from the closest objective. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

After the Split: Partition,Successor States,and the Dynamics of War in the Horn of Africa

Why do partitioned successor states engage one another in armed conflict? We explore the drivers of war between successor states by comparing two border crises that followed the partitions of Ethiopia (1993) and Sudan (2011). We argue that the politico-military struggles that give way to partition create important historical memories that shape what successor states think about the utility of military force. While the partition of Ethiopia yielded successor states led by regimes that were victors of the preceding war of partition, the war of partition in Sudan produced successor states that emerged out of military stalemate. This distinction explains why Ethiopia and Eritrea waged a costly border war that Sudan and South Sudan were able to avoid.     

British intelligence and the Soviet atomic bomb, 1945–1950

With relations with the Soviet Union growing ever ‘hotter’, it became essential for the British to comprehend Soviet atomic development. However, British intelligence had to rely on more overt methods of intelligence collection, which provided an inadequate basis from which to proceed. This was further hindered by the interpretation of such information on the basis of Anglo-American development and by the 1946 McMahon Act. Accordingly the first Soviet atomic bomb in August 1949 was not accurately predicted by the British. Meanwhile British war planning centred on the year 1957, based – it was argued – on strategic forecasts. Yet the impact of recently released intelligence material throws this into question, and instead reveals that the date reflected British war readiness, rather than when British intelligence predicted the Soviet Union would have achieved the nuclear capability to wage a successful war.     

The salvo combat model with area fire

This article analyzes versions of the salvo model of missile combat where area fire is used by one or both sides in a battle. Although these models share some properties with the area fire Lanchester model and the aimed fire salvo model, they also display some interesting differences, especially over the course of several salvos. Although the relative size of each force is important with aimed fire, with area fire, it is the absolute size that matters. Similarly, although aimed fire exhibits square law behavior, area fire shows approximately linear behavior. When one side uses area fire and the other uses aimed fire, the model displays a mix of square and linear law behavior. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 652–660, 2013