Efficient multinomial selection in simulation

Consider a simulation experiment consisting of v independent vector replications across k systems, where in any given replication one system is selected as the best performer (i.e., it wins). Each system has an unknown constant probability of winning in any replication and the numbers of wins for the individual systems follow a multinomial distribution. The classical multinomial selection procedure of Bechhofer, Elmaghraby, and Morse (Procedure BEM) prescribes a minimum number of replications, denoted as v*, so that the probability of correctly selecting the true best system (PCS) meets or exceeds a prespecified probability. Assuming that larger is better, Procedure BEM selects as best the system having the largest value of the performance measure in more replications than any other system. We use these same v* replications across k systems to form (v*)^k pseudoreplications that contain one observation from each system, and develop Procedure AVC (All Vector Comparisons) to achieve a higher PCS than with Procedure BEM. For specific small-sample cases and via a large-sample approximation we show that the PCS with Procedure AVC exceeds the PCS with Procedure BEM. We also show that with Procedure AVC we achieve a given PCS with a smaller v than the v* required with Procedure BEM. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 459–482, 1998     

Minimax and maximin facility location problems on a sphere

The problem dealt with in this article is as follows. There are n “demand points” on a sphere. Each demand point has a weight which is a positive constant. A facility must be located so that the maximum of the weighted distances (distances are the shortest arcs on the surface of the sphere) is minimized; this is called the minimax problem. Alternatively, in the maximin problem, the minimum weighted distance is maximized. A setup cost associated with each demand point may be added for generality. It is shown that any maximin problem can be reparametrized into a minimax problem. A method for finding local minimax points is described and conditions under which these are global are derived. Finally, an efficient algorithm for finding the global minimax point is constructed.     

Parametric studies in transportation-type problems

In this paper we present some results in parametric studies on several transportation-type problems. Specifically, a characterization is obtained for the optimal values of the variables in the problem of determining an optimal growth path in a logistics system. We also derive an upper bound beyond which the optimal growth path remains the same. The results are then extended to the goal programming model and the prespecified market growth rate problem.     

Multiperiod capacity expansion and shipment planning with linear costs

In this paper we consider a multiperiod deterministic capacity expansion and shipment planning problem for a single product. The product can be manufactured in several producing regions and is required in a number of markets. The demands for each of the markets are non-decreasing over time and must be met exactly during each time period (i.e., no backlogging or inventorying for future periods is permitted). Each region is assumed to have an initial production capacity, which may be increased at a given cost in any period. The demand in a market can be satisfied by production and shipment from any of the regions. The problem is to find a schedule of capacity expansions for the regions and a schedule of shipments from the regions to the markets so as to minimize the discounted capacity expansion and shipment costs. The problem is formulated as a linear programming model, and solved by an efficient algorithm using the operator theory of parametric programming for the transporation problem. Extensions to the infinite horizon case are also provided.     

Optimal location of a facility relative to area demands

This paper deals with the Weber single-facility location problem where the demands are not only points but may be areas as well. It provides an iterative procedure for solving the problem with l^p distances when p > 1 (a method of obtaining the exact solution when p = 1 and distances are thus rectangular already exists). The special case where the weight densities in the areas are uniform and the areas are rectangles or circles results in a modified iterative process that is computationally much faster. This method can be extended to the simultaneous location of several facilities.     

Algeria: A case study of insurgency in the new world order

Much of the literature on the decolonization of Namibia is set in a narrative mode and demonizes one or the other of the protagonists. This article, organized in a topical fashion, concerns the diplomatic, military, and economic facets of the Namibian war and draws upon the literature of comparable twentieth century colonial and anti-colonial wars in Algeria, Angola, Kenya, Mozambique, the Philippines, South Africa, Vietnam and Zimbabwe. It explores the changing discourse of legitimacy concerning independence for Namibia, the conduct of insurgency and counterinsurgency in the bush war, and economic aspects of that war.     

COUP D'ÉTAT IN SÃO TOMÉ AND PRÍNCIPE

This paper argues for effective parliamentarian oversight of the expenditure of the security services. It discusses the general principles of public expenditure management and submits that, as the security services render a public service using public monies, they need to be subject to the same principles. The most important of these principles in relation to the security services are those of transparency and accountability. The security services are, however, involved in sensitive issues of state security and some modification in the application of these principles can be substantiated. Not detracting from the principles of public expenditure management and parliamentary oversight, special provisions regarding the management of security expenditure can be instituted. These include special legislation, the conduct of closed parliamentary committee meetings, and the institution of special parliamentary committees. The fundamental question is, however, ‘who decides’. The paper argues that the answer to this question lies squarely in the domain of parliament, which should ultimately decide on any deviations and exclusions from these principles as related to the security services.