Algorithms for the minimax transportation problem

In this paper, we consider a variant of the classical transportation problem as well as of the bottleneck transportation problem, which we call the minimax transportation problem. The problem considered is to determine a feasible flow x_ij from a set of origins I to a set of destinations J for which max_(i,j)εIxJ{c_ijx_ij} is minimum. In this paper, we develop a parametric algorithm and a primal-dual algorithm to solve this problem. The parametric algorithm solves a transportation problem with parametric upper bounds and the primal-dual algorithm solves a sequence of related maximum flow problems. The primal-dual algorithm is shown to be polynomially bounded. Numerical investigations with both the algorithms are described in detail. The primal-dual algorithm is found to be computationally superior to the parametric algorithm and it can solve problems up to 1000 origins, 1000 destinations and 10,000 arcs in less than 1 minute on a DEC 10 computer system. The optimum solution of the minimax transportation problem may be noninteger. We also suggest a polynomial algorithm to convert this solution into an integer optimum solution.     

What Goes Up Must Come Down: Military Expenditure and Civil Wars

Abstract

This paper examines the impact of civil war on military expenditure. We employ two measures of military expenditure: the share of military expenditure in general government expenditure and the logarithm of military expenditures. We would reasonably expect a priori that military expenditure as a share of general government expenditure increases during a civil war and that such increases would taper off over the duration of a civil war. We also explore whether the termination of a civil war induces a decline in the share of military expenditure as a share of the general government expenditure in the short-run. We find evidence the of share of military expenditure increases during a civil war and falls in the year succeeding the end of a civil war, and, in particular, if a war ends in a peace treaty. The level of military expenditures, however, rises during civil wars and does not appear to decline in the short-term after the end of a civil war.     

Local perceptions of the EU’s role in peacebuilding: The case of security sector reform in Palestine

ABSTRACT

Perception research can make a valuable contribution to the study of the local dimension in EU peacebuilding. The conceptual framework developed in this article distinguishes between perceptions of the “legitimacy,” “effectiveness,” and “credibility” of EU peacebuilding practices, which are crucial factors for successful peacebuilding. Relying on the case of the EU’s support for security sector reform (SSR) in Palestine, this article shows that local stakeholders—which participate in various EU-sponsored training and capacity-building programs—display considerable support for liberal peacebuilding norms. Yet, perceived discrepancies between the EU’s peacebuilding rhetoric and its SSR activities have severely undermined the potential of the EU’s liberal peacebuilding model in the eyes of Palestinian stakeholders. Critical local perceptions are frequently articulated with reference to the EU’s own liberal peacebuilding discourse, pointing to a lack of inclusiveness of the SSR process and deficits in terms of democratic governance and the rule of law.     

Mirror,mirror on the wall,who is the most offensive of them all? – Explaining the offensive bias in military tactical thinking

This article explores why the offensive predominates military tactical thinking. With survey results showing an offensive bias among 60 per cent of senior Swedish officers and as many as 80 per cent in the case of the army, it is clear that this is not just a problem of the past but is equally relevant today. The article asks why there is a tendency to perceive and understand offensive tactics as the preferred choice and the way to conduct battle that should be encouraged and preferred. Drawing on existing research and the findings of a pilot study, ten propositions for why the offensive bias exists are tested using a mixed-method approach. Based on the findings, the article develops a model to understand why the offensive dominates military tactical thinking. It is found that the two key constitutive factors behind the offensive bias are military culture and education. These factors most directly and profoundly influence an officer’s identity, perceptions, and thinking. Military culture and education, in turn, work as a prism for four other factors: military history, the theory and principles of war, doctrine and TTPs, and psychological factors.     

Proactive release procedures for just‐in‐time job shop environments,subject to machine failures

In this paper, we consider just‐in‐time job shop environments (job shop problems with an objective of minimizing the sum of tardiness and inventory costs), subject to uncertainty due to machine failures. We present techniques for proactive uncertainty management that exploit prior knowledge of uncertainty to build competitive release dates, whose execution improves performance. These techniques determine the release dates of different jobs based on measures of shop load, statistical data of machine failures, and repairs with a tradeoff between inventory and tardiness costs. Empirical results show that our methodology is very promising in comparison with simulated annealing and the best of 39 combinations of dispatch rules & release policies, under different frequencies of breakdowns. We observe that the performance of the proactive technique compared to the other two approaches improves in schedule quality (maximizing delivery performance while minimizing costs) with increase in frequency of breakdowns. The proactive technique presented here is also computationally less expensive than the other two approaches. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

Optimal service rates of a service facility with perishable inventory items

In this paper we optimally control service rates for an inventory system of service facilities with perishable products. We consider a finite capacity system where arrivals are Poisson‐distributed, lifetime of items have exponential distribution, and replenishment is instantaneous. We determine the service rates to be employed at each instant of time so that the long‐run expected cost rate is minimized for fixed maximum inventory level and capacity. The problem is modelled as a semi‐Markov decision problem. We establish the existence of a stationary optimal policy and we solve it by employing linear programming. Several numerical examples which provide insight to the behavior of the system are presented. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 464–482, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10021