The maximum collection problem with time-dependent rewards

We consider a routing problem where the objective is to maximize the sum of the rewards collected at the nodes visited. Node rewards are decreasing linear functions of time. Time is spent when traveling between pairs of nodes, and while visiting the nodes. We propose a penalty-based greedy (heuristic) algorithm and a branch-and-bound (optimal) algorithm for this problem. The heuristic is very effective in obtaining good solutions. We can solve problems with up to 20 nodes optimally on a microcomputer using the branch-and-bound algorithm. We report our computational experience with this problem. © 1996 John Wiley & Sons, Inc.     

Optimal shift scheduling: A branch‐and‐price approach

We present a branch‐and‐price technique for optimal staff scheduling with multiple rest breaks, meal break, and break windows. We devise and implement specialized branching rules suitable for solving the set covering type formulation implicitly, using column generation. Our methodology is more widely applicable and computationally superior to the alternative methods in the literature. We tested our methodology on 365 test problems involving between 1728 and 86400 shift variations, and 20 demand patterns. In a direct comparison with an alternative method, our approach yields significant improvements both in cpu time and in the number of problem instances solved to optimality. The improvements were particularly marked for problems involving larger numbers of feasible shifts. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 185–200, 2000     

Automated air load planning

We describe the development of a heuristic algorithm for determining efficient 2-dimensional packings in cargo aircraft where cargo placement constraints are critically important in determining the feasibility of packing locations. We review the performance of a new algorithm versus some traditional ones for aircraft loading. The algorithm is also tested in a more generalized setting where there exist no additional constraints on items, to suggest applicability in other environments. The new algorithm has been used worldwide in the Automated Air Load Planning System (AALPS) for cargo aircraft loading, with much success. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 751–768, 1998     

Attacking the Atom: Does Bombing Nuclear Facilities Affect Proliferation?

Abstract

What are the consequences of military strikes against nuclear facilities? In particular, do they ‘work’ by delaying the target states ability to build the bomb? This article addresses these questions by conducting an analysis of 16 attacks against nuclear facilities from 1942 to 2007. We analyze strikes that occurred during peacetime and raids that took place in the context of an ongoing interstate war. The findings indicate that strikes are neither as uniformly fruitless as the skeptics would suggest, nor as productive as advocates have claimed. There is evidence that the peacetime attacks delayed the target's nuclear program, although the size of this effect is rather modest. The wartime cases were less successful, as attacks often missed their targets either due to operational failure or limited intelligence on the location of critical targets. In our concluding section we show that many of the conditions that were conducive to past success are not present in the contemporary Iran case. Overall, our findings reveal an interesting paradox. The historical cases that have successfully delayed proliferation are those when the attacking state struck well before a nuclear threat was imminent. Yet, this also happens to be when strikes are the least legitimate under international law, meaning that attacking under these conditions is most likely to elicit international censure.     

Bringing Balancing Back In: Britain's Targeted Balancing, 1936–1939

This article challenges the conventional wisdom that Neville Chamberlain rejected the British tradition of balance of power in the 1930s. In contrast to balance of power and balance of threat theories, states do not balance against aggregate or net shifts in power. Instead, leaders define threats based on particular elements of a foreign state's power. The import is that different components of power of a foreign state are more or less threatening and aggregate shifts in power alone may not provoke counterbalancing behavior. In the 1930s, Britain balanced against the most threatening components of power: the German Luftwaffe and the threat of a knock-out air assault against the homeland, Japan's Imperial Navy and its threat to Britain's commercial trade routes and the Dominions in East Asia, and the Italian Navy and the threat to Britain's line of communication through the Mediterranean Sea to India and Asia. Given Britain's difficult financial circumstances, all other components of power, such as the army and the land components of power of Germany, Japan, and Italy were ranked as secondary in terms of its rearmament priorities. Thus, London was able to narrow the gap with Berlin in specific components of power of strategic importance such as aircraft production or to exceed Germany in other areas such as the Royal Navy and its battlefleet.     

Decommissioning and paramilitary strategy in Northern Ireland: A problem compared

This study examines the problems of paramilitary decommissioning in Northern Ireland. It analyses why decommissioning has become so contentious in the Northern Ireland peace process. Decommissioning, though, is not a unique or intrinsically insurmountable problem. This is demonstrated by highlighting the issue in international context. Three examples of decommissioning in conflict resolution processes are assessed: the Lebanon, El Salvador and Mozambique. These varied examples do supply some limited lessons for Northern Ireland. This study argues that the explanation for the intractability of decommissioning in Northern Ireland resides, to a greater extent, in the tactical and strategic reasoning of the main paramilitary groupings in Northern Ireland. The factors that condition their thinking, however, can be found in the nature of the peace process itself which provides the paramilitiaries with every incentive to retain possession of their weapons.     

An alliance between Cyprus and Greece: assessing its partners’ relative security contribution

The issue that this paper tackles is the assessment of the relative security benefits that Cyprus and Greece derive in the context of their cooperation on defence matters. This form of cooperation, known as the ‘Integrated Defence Space Doctrine’, aims at defending their interests in the Aegean Sea and the broader East Mediterranean theatre. The paper relies heavily on earlier research on this topic, which deals with the Greek–Cypriot alliance facing an arms race against Turkey, and uses a coefficient especially designed to assess the optimal levels of security and the associated defence expenditure of the two allies. A comparison of the relative security coefficient values for the two allies suggests that the security benefit that Greece derives thanks to its alliance with Cyprus exceeds the corresponding Cypriot benefit by far. Given the importance assigned to human resources by this index, in conjunction with the demographic problems of Greece, this conclusion justifies the recent Greek defence policy revision, emphasizing quality, capital equipment and flexibility of forces. This revision aims at satisfying the security requirements of the alliance and the increasing demands of an arms race against Turkey.