The orienteering problem

Orienteering is a sport in which start and end points are specified along with other locations. These other locations have associated scores. Competitors seek to visit, in a fixed amount of time, a subset of these locations on the way from the start point to the end point in order to maximize the total score. An effective center-of-gravity heuristic is presented that outperforms heuristics from the literature.     

The Needs of Political Policy versus the Reality of Military Operations: Royal Navy Opposition to the Arctic Convoys, 1942

It has become commonplace, especially in the post-Vietnam strategic environment, to quote Clausewitz's dictum that war is the continuation of policy by other means. We are told that military operations are dictated by, and must serve, clear political ends. Such thinking has been invoked to support everything from punitive strikes, to peacekeeping missions, to the ‘Powell’ doctrine and its political ‘exit strategies’, but at times political policy and military operations do not mix. In 1942 the Royal Navy bowed to political pressure and, against its collective better judgement, continued the Arctic convoys to the Soviet Union. These military operations culminated in the destruction of convoy PQ 17 in early July. This conflict between political policy and military strategy provides an object lesson of why in war issues of means and priorities must outweigh the importance of any given political policy.     

The individual station technique for the analysis of cyclic polling systems

Polling systems are used to model a wide variety of real-world applications, for example, telecommunication and material handling systems. Consequently, there is continued interest in developing efficient algorithms to analyze the performance of polling systems. Recent interest in the optimization of these systems has brought up the need for developing very efficient techniques for analyzing their waiting times. This article presents the Individual Station technique for cyclic polling systems. The technique possesses the following features: (a) it allows the user to compute the mean waiting time at a selected station independent of the mean waiting time computations at other stations, and (b) its complexity is low and independent of the system utilization. In addition the technique provides explicit closed-form expressions for (i) the mean waiting times in a system with 3 stations, and (ii) the second moment of the waiting times in a system with 2 stations, for an exhaustive service system. © 1996 John Wiley & Sons, Inc.     

Shifting power,preventive logic,and the response of the target: Germany,Russia, and the First World War

If a declining state has incentives for preventive war, the rising state should have incentives to delay a confrontation until it is stronger. We develop the theoretical paradox and examine the July 1914 crisis. Why did Russia, rising relative to Germany, not adopt a buying-time strategy? We argue that although most Russian leaders hoped to avoid a confrontation, they feared that the failure to support Serbia would lead to a loss of Russian credibility and a significant setback to Russia’s position in the Balkans, one that could not easily be reversed, even with Russia’s expected increase in relative military power.     

MACROECONOMIC ASPECTS OF INTERNAL CONFLICTS: A CONCEPTUALISATION

This exploratory paper outlines the special macroeconomic features of countries populated by two groups of people engaged in internal conflict yet forming a central government for generating benefits that cannot be privately attained. Each group exerts an influence on the central government in accordance with its relative military strength. The central government collects taxes, exports the country’s natural resources and tourist attractions, attracts external grants and loans, and distributes the net revenues between the rival groups. The paper highlights the implications of the groups’ investment in military strength for the state’s net revenues and their distribution, for the state’s external debt, and for the groups’ ability to maintain and increase their ranks, production capital and per capita income.     

The optimal size of a storage facility

The appropriate size for a piece of fixed capital equipment (measured in units of capacity) depends on the anticipated demand for its services and on its cost. Using several models developed in the study of optimal inventory policy we derive the contribution to cost reduction that additional storage space makes under each of these models. Comparison of the sum of the discounted benefits (ie., reduced operating cost) with construction costs for additional storage space then yields the optimal size of the storage facility.     

Analysis of project scheduling strategies in a client-contractor environment

In this article we consider a cost-minimization model to investigate scheduling strategies for multistaged projects in a client-contractor environment. This type of environment is symptomatic of temporal changes in project definition and scope. At prespecified epochs the client conducts an external evaluation of the project and either accepts or rejects the contractor's current work. The resulting uncertainty from the client's review is modeled via monotonically varying acceptance probabilities. The model is designed primarily to address the interaction between earliest-, intermediate-, and latest-start options and project-crashing stragies for a broad range of penalty costs. Theoretical results are introduced, while numerical examples for both exponentially and polynomially based acceptance probabilities are discussed.     

A probabilistic evaluation of helicopter lift capability

This paper describes a technique for the calculation of the probability that a helicopter can lift a specified load, or number of loads with a specified frequency distribution, in a given geographical region. This probability is computed by determining the bivariate altitude-temperature probability distribution for the specified region. The payload capability at any given temperature and altitude is calculated from standard performance equations. By integrating this over the altitude-temperature distribution, it is possible to obtain the probability distribution of payload capability, from which the required probabilities of lifting specific loads can be determined.