Simulating nonhomogeneous poisson processes with proportional intensities

The purpose of this research is to investigate simulation algorithms for nonhomogeneous Poisson processes with proportional intensities. Two algorithmic approaches are studied: inversion and thinning. Motivated by industrial practices, the covariate vector involved in the simulation is permitted to change after every event (or observation). The algorithms are extended to permit the simulation of general nonhomogeneous Poisson processes with possible discontinuities both in baseline intensity and covariate vector. This latter extension can be used to facilitate a wide range of failure situations that can arise with repairable systems. © 1994 John Wiley & Sons, Inc.     

Cost analysis and extension of a simple maintenance-scheduling heuristic

Practitioners of maintenance scheduling sometimes use a simple analytic formula, derived based on inspection scheduling, as a heuristic to determine the length of the preventive maintenance period. The sensitivity of this heuristic solution is analyzed and the cost penalties are calculated compared to the exact solution that utilizes the lifetime distribution in the derivation of the optimal preventive maintenance period. A simple extension of the heuristic is suggested to improve the approximation with a slightly increased computational effort. The sensitivity and cost analysis of the improved heuristic are discussed as well. © 1994 John Wiley & Sons, Inc.     

Search techniques for a nonlinear multiprocessor scheduling problem

The problem of assigning computer program modules to functionally similar processors in a distributed computer network is investigated. The modules of a program must be assigned among processors in such a way as to minimize interprocessor communication while taking advantage of affinities of certain modules to particular processors. This problem is formulated as a zero-one quadratic programming problem, but is more conveniently modeled as a directed acyclic search graph. The model is developed and a backward shortest path labeling algorithm is given that produces an assignment of program modules to processors. A non-backtracking branch-and-bound algorithm is described that uses a local neighborhood search at each stage of the search graph.     

Some limiting distributions associated with sequences of multinomial trials

A series of independent trials is considered in which one of k ≥ 2 mutually exclusive and exhaustive outcomes occurs at each trial. The series terminates when m outcomes of any one type have occurred. The limiting distribution (as m → ∞) of the number of trials performed until termination is found with particular attention to the situation where a Dirichlet distribution is assigned to the k vector of probabilities for each outcome. Applications to series of races involving k runners and to spares problems in reliability modeling are discussed. The problem of selecting a stopping rule so that the probability of the series terminating on outcome i is k^?1 (i.e., a “fair” competition) is also studied. Two generalizations of the original asymptotic problem are addressed.     

The proper balancing of repair and preventive maintenance activities in the determination of coordinated shipboard allowance lists

The determination as to the cost-effective number of spares for given types of items or equipment to be carried on board various types of ships is studied. This spare pool, known as the ship's COSAL, must provide prespecified levels of protection against stockouts for all uses of that item on board the given ship. This article derives and illustrates the methodology for optimally trading off the reduction in the ship's COSAL that can be gained by improving repair/resupply capabilities or by lowering the failure rate of the equipment through more or different types of preventive maintenance. A flexible class of preventive maintenance/repair response functions to cost is studied which are nonlinear and exhibit realistic diminishing returns. Two different types of assumptions are possible regarding the interdependencies of the resupply times across different ship types. A tractable budget allocation method is presented which can be used in a multiitem, multiship, multiechelon repair environment where there is one budget to cover all spares, all repair/resupply, and preventive maintenance activities. The technique incorporates different criticalities of shortages by type of ship and item. It can be used either in a budget building mode or a budget execution mode.     

What you should know about simulation and derivatives

Derivatives (or gradients) are important for both sensitivity analysis and optimization, and in simulation models, these can often be estimated efficiently using various methods other than brute‐force finite differences. This article briefly summarizes the main approaches and discusses areas in which the approaches can most fruitfully be applied: queueing, inventory, and finance. In finance, the focus is on derivatives of another sort. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Book reviews

European Security in the New Political Environment by James H. Wyllie, London: Addison, Wesley Longman, 1997, ISBN 0-582-24403-X (pbk), £13.99

Russia and Europe: The Emerging Security Agenda edited by Vladimir Baranovsky, Oxford: Oxford University Press, SIPRI, 1997, ISBN 0-19-829201-5 (hbk), £45.00

The Defeat of Japan by David Rees, Westport, Connecticut and London: Praeger, ISBN 0-275-95955-4 (hbk), £46.50

The Collective Naval Defence of the Empire, 1900-1940 by Nicholas Tracy (ed.), London: Ashgate, for the Navy Records Society, 1997, ISBN 1859-284-027 (hbk), £59.50

Knights in White Armour The New Art of War and Peace by Christopher Bellamy, London: Pimlico Press, 1997, ISBN 0-7126-739-03 (pbk), £12.50

Regional Orders: Building Security in a New World by avid A. Lake and Patrick M. Morgan (eds), University Park: Penn State Press, 1997, ISBN 0-271-01703-i (hbk), £49.50/$55, ISBN 0-271-01704-X (pbk), £7.95/$19.95

Contested Social Orders and International Politics by David Skidmore (ed.), Nashville: Vanderbilt University Press, 1997, ISBN 0-8265-1284-4 (hbk), $32.95

The Politics of Threat: Minuteman Vulnerability in American National Security Policy by David H. Dunn. London: Macmillan Press, 1997, ISBN 0-333-67816-8 (hbk), £45.00

The Sociology of the Military by Guiseppe Caforio (ed.), Cheltenham: Edward Elgar, 1998, ISBN 1-85898-619-2, 704 pp., £150

The Nordic Nations in the New Western Security Regime by Ingemar Dorfer, Baltimore: Johns Hopkins University Press, 1997, ISBN 0-943875-83-8 (hbk), £27, ISBN 0-943875-82-X (pbk), £13     

Landmarks in defense literature

A Study of War by Quincy Wright, Second edition. Chicago: University of Chicago Press, 1965, 1,637 pp.     

气动剥离液滴的附面层分析方法

本文根据附面层理论,对高速气流中的液滴,因气流和液滴表面相互作用而产生的气动剥离现象进行了分析,建立了气液两相附面层耦合问题的理论分析模型,得到了发生气动剥离时的最小气流速度的计算公式,为液体燃料在高速气流申雾化机理研究提供参考。