Maintenance of a device with age-dependent exponential failures

We consider a device that deteriorates over time according to a Markov process so that the failure rate at each state is constant. The reliability of the device is characterized by a Markov renewal equation, and an IFRA (increasing failure rate on average) property of the lifetime is obtained. The optimal replacement and repair problems are analyzed under various cost structures. Furthermore, intuitive and counterintuitive characterizations of the optimal policies and results on some interesting special problems are presented. © 1992 John Wiley & Sons, Inc.     

GENDER AND ATTITUDES TOWARD PROFESSIONAL ETHICS

This study was designed to examine the influence of gender and age on attitudes toward professional ethics among a sample of the Nigeria police officers. Using a cross-sectional survey, data was collected from a total of 163 participants. Results revealed that gender and age were significant predictors of unethical beliefs; female and older police participants were also more ethical than their male and younger counterparts. These findings were discussed in the context of socialization theory, Gilligan's moral development theory and other organisational practices, while its practical implications for the recruitment, selection and placement in the Nigeria police were also emphasized.     

THE ACRS EXPERIENCE AND ITS RELEVANCE TO THE WMDFZ CONFERENCE

This article examines the arms control logic that was applied to the only regional arms control talks that have taken place in the Middle East to date: the Arms Control and Regional Security (ACRS) working group that was part of the multilateral track of the Madrid peace process in the early 1990s. It highlights both the successes and major constraints of the ACRS talks in an effort to assess what might be relevant to the weapons of mass destruction-free zone conference proposed for later this year. In addition to the basic arms control dilemmas that will continue to challenge this conference—as they did ACRS—the article suggests that current conditions in the Middle East are even less conducive to regional dialogue than they were in the earlier period, due to the internal upheavals in several key Arab states, and the specific challenge of Iran's move to develop a military nuclear capability.     

A Doctrine without Dogma

ABSTRACT

In No Use: Nuclear Weapons and U.S. National Security Policy, Thomas M. Nichols calls for a constructive rethinking about the history of nuclear weapons and the attitudes that have grown up around them. Despite dramatic reductions since the end of the Cold War, the United States still maintains a robust nuclear triad that far exceeds the needs of realistic deterrence in the twenty-first century. Nichols advocates a new strategy of minimum deterrence that includes deep unilateral reductions to the US nuclear arsenal, a no-first-use pledge, withdrawing US tactical nuclear weapons from Europe, and ending extended nuclear deterrence for allies. The weakest part of his argument eschews nuclear retaliation against small nuclear states that attack the United States, opting instead to use only conventional weapons to guarantee regime change. He admits this will entail enormous cost and sacrifice, but cites the “immorality” of retaliating against a smaller power with few targets worthy of nuclear weaponry, which totally ignores the massive underground facilities constructed to shield military facilities in many of these states. Despite this, Nichols's thoughtful approach to post-Cold War deterrence deserves thoughtful consideration.     

Generalized orienteering problem with resource dependent rewards

We introduce a generalized orienteering problem (OP) where, as usual, a vehicle is routed from a prescribed start node, through a directed network, to a prescribed destination node, collecting rewards at each node visited, to maximize the total reward along the path. In our generalization, transit on arcs in the network and reward collection at nodes both consume a variable amount of the same limited resource. We exploit this resource trade‐off through a specialized branch‐and‐bound algorithm that relies on partial path relaxation problems that often yield tight bounds and lead to substantial pruning in the enumeration tree. We present the smuggler search problem (SSP) as an important real‐world application of our generalized OP. Numerical results show that our algorithm applied to the SSP outperforms standard mixed‐integer nonlinear programming solvers for moderate to large problem instances. We demonstrate model enhancements that allow practitioners to represent realistic search planning scenarios by accounting for multiple heterogeneous searchers and complex smuggler motion. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Maritime interdiction in Sri Lanka's counterinsurgency

A comprehensive maritime interdiction strategy to attack the insurgent's logistic system was a key element in the defeat of the Tamil Tigers. The campaign of maritime interdiction required the Sri Lankan Navy (SLN) to attack LTTE arms smuggling, sea piracy, and maritime terrorism. The SLN degraded the insurgency's robust maritime logistical network while also devising tactics to engage the maritime insurgents who reacted with swarm and suicide boat tactics. The efforts of the SLN forced the Tamil Tigers to confront the government's final land offensives with diminished resources, thus collapsing a three decades’ old insurgency in a matter of months.     

On valuing appreciating human assets in services

This paper derives optimal policies for when to hire, train, and lay off employees in service organizations when worker productivity appreciates deterministically or stochastically under constant, monotonic, and cyclic service demand. The model, an extension of the machine replacement problem from the engineering economy literature, uses infinite horizon linear programming to produce optimal personnel planning strategies and dual prices that characterize the workforce's economic value. The effect of employee attrition is also considered. In its valuation of human assets, unlike pure accounting approaches that only try to measure, this paper proposes an approach to capture the interaction between firm decisions pertaining to human resources and human resource value. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Some experiences using MIL-STD-105 in the united states air force

The historical and, to some extent, the current role of attribute inspection sampling in the United States Air Force is described. Some insight into consideration culminating in revisions made to the original MIL-STD-105 sampling plans is provided. These revisions were motivated from a practitioner's perspective rather than that of a statistical expert. Some significant administrative applications within the Air Force are described, and a practical method, based on the total amount of inspection, is given for distinguishing between sampling plans that have a fixed risk level (i.e., common value on the OC curves).     

A simple Markov model for the analysis of multiple air combat

It is proposed to describe multiple air-to-air combat having a moderate number of participants with the aid of a stochastic process based on end-game duels. A simple model describing the dominant features of air combat leads to a continuous time discrete-state Markov process. Solution of the forward Kolmogorov equations enables one to investigate the influence of initial force levels and performance parameters on the outcome probabilities of the multiple engagement. As is illustrated, such results may be useful in the decision-making process for aircraft and weapon system development planning. Some comparisons are made with Lanchester models as well as with a semi-Markov model.