A new approach for dealing with the startup problem in discrete event simulation

This article proposes a practical, data-based statistical procedure which can be used to reduce or remove bias owing to artificial startup conditions in simulations aimed at estimating steady-state means. We discuss results of experiments designed to choose good parameter values for this procedure, and present results of extensive testing of the procedure on a variety of stochastic models for which partial analytical results are available. The article closes with two illustrations of the application of the procedure to more complex statistical problems which are more representative of the kinds of purposes for which real-world steady-state simulation studies might be undertaken.     

Landmarks in defense literature

Military operations and maritime preponderance by Charles E. Callwell, Edinburgh: William Blackwood & Sons, 1905.     

Techniques for establishing ergodic and recurrence properties of continuous-valued markov chains

We present techniques for classifying Markov chains with a continuous state space as either ergodic or recurrent. These methods are analogous to those of Foster for countable space chains. The theory is presented in the first half of the paper, while the second half consists of examples illustrating these techniques. The technique for proving ergodicity involves, in practice, three steps: showing that the chain is irreducible in a suitable sense; verifying that the mean hitting times on certain (usually bounded) sets are bounded, by using a “mean drift” criterion analogous to that of Foster; and finally, checking that the chain is such that bounded mean hitting times for these sets does actually imply ergodicity. The examples comprise a number of known and new results: using our techniques we investigate random walks, queues with waiting-time-dependent service times, dams with general and random-release rules, the s-S inventory model, and feedback models.     

Two queueing systems sharing the same finite waiting room

In this paper, we consider the analysis of two M/G/1 queueing systems sharing the same finite waiting room. An exact analysis is given for several special cases, and then an algorithm is developed which approximates the system behavior for the general problem. Comparisons are made between the special cases and the algorithm.     

Multiple-attribute decision making with partial information: The comparative hypervolume criterion

A new approach is presented for analyzing multiple-attribute decision problems in which the set of actions is finite and the utility function is additive. The problem can be resolved if the decision makers (or group of decision makers) specifies a set of nonnegative weights for the various attributes or criteria, but we here assume that the decision maker(s) cannot provide a numerical value for each such weight. Ordinal information about these weights is therefore obtained from the decision maker(s), and this information is translated into a set of linear constraints which restrict the values of the weights. These constraints are then used to construct a polytope W of feasible weight vectors, and the subsets H_i (polytopes) of W over which each action a_i has the greatest utility are determined. With the Comparative Hypervolume Criterion we calculate for each action the ratio of the hypervolume of H_i to the hypervolume of W and suggest the choice of an action with the largest such ratio. Justification of this choice criterion is given, and a computational method for accurately approximating the hypervolume ratios is described. A simple example is provided to evaluate the efficiency of a computer code developed to implement the method.     

Law Enforcement Intelligence: A Call for New Strategies and Tactics in Countering Criminal Insurgency

This paper underscores the theory that efficacious law enforcement intelligence addresses current problems of criminal insurgency including acts of terrorism, asymmetric warfare and low intensity conflict, and suggests possible solutions. By introducing the notion of crime as insurgency, a new paradigm may be developed that could assist practitioners and academics alike in analyzing, solving and managing crime. By shifting the perspective for both military and civilian forces from their traditionally reactive stance, to a proactive posture, and merging national security with homeland defense on the most perplexing issues and threats facing US security, this work may provide a base upon which new and actionable policies can be designed. Public administrators must take seriously the lessons from past failures. The single most important supposition being, sound policy is reliant upon good intelligence.     

Polynomial‐time approximation schemes for two‐machine open shop scheduling with nonavailability constraints

This paper addresses a two‐machine open shop scheduling problem, in which the machines are not continuously available for processing. The processing of an operation affected by a non‐availability interval can be interrupted and resumed later. The objective is to minimize the makespan. We present two polynomial‐time approximation schemes, one of which handles the problem with one non‐availability interval on each machine and the other for the problem with several non‐availability intervals on one of the machines. Problems with a more general structure of the non‐availability intervals are not approximable in polynomial time within a constant factor, unless . © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

Dynamic proximity calculations for situation awareness

We apply dynamic proximity calculations (density and clustering) from dynamic computational geometry to a military application. The derived proximity information serves as an abstract view of a current situation in the battlefield that can help a military commander achieve situation awareness. We employ Delaunay triangulation as a computational tool in our framework, and study its dynamic update in depth. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004.