Effects of cueing in cooperative search

We consider the effects of cueing in a cooperative search mission that involves several autonomous agents. Two scenarios are discussed: one in which the search is conducted by a number of identical search‐and‐engage vehicles and one where these vehicles are assisted by a search‐only (reconnaissance) asset. The cooperation between the autonomous agents is facilitated via cueing, i.e., the information transmitted to the agents by a searcher that has just detected a target. The effect of cueing on the target detection probability is derived from first principles using a Markov chain analysis. In particular, it is demonstrated that the benefit of cueing on the system's effectiveness is bounded. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

The impact of manufacturer rebates on supply chain profits

Manufacturer rebates are commonly used as price discount tools for attracting end customers. In this study, we consider a two‐stage supply chain with a manufacturer and a retailer, where a single seasonal product faces uncertain and price‐sensitive demand. We characterize the impact of a manufacturer rebate on the expected profits of both the manufacturer and the retailer. We show that unless all of the customers claim the rebate, the rebate always benefits the manufacturer. Our results thus imply that “mail‐in rebates,” where some customers end up not claiming the rebate, particularly when the size of the rebate is relatively small, always benefit the manufacturer. On the other hand, an “instant rebate,” such as the one offered in the automotive industry where every customer redeems the rebate on the spot when he/she purchases a car, does not necessarily benefit the manufacturer. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Changing the paradigm: Simulation,now a method of first resort

Decades ago, simulation was famously characterized as a “method of last resort,” to which analysts should turn only “when all else fails.” In those intervening decades, the technologies supporting simulation—computing hardware, simulation‐modeling paradigms, simulation software, design‐and‐analysis methods—have all advanced dramatically. We offer an updated view that simulation is now a very appealing option for modeling and analysis. When applied properly, simulation can provide fully as much insight, with as much precision as desired, as can exact analytical methods that are based on more restrictive assumptions. The fundamental advantage of simulation is that it can tolerate far less restrictive modeling assumptions, leading to an underlying model that is more reflective of reality and thus more valid, leading to better decisions. Published 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 293–303, 2015     

Optimal replacement of continuously degrading systems in partially observed environments

Motivated by wind energy applications, we consider the problem of optimally replacing a stochastically degrading component that resides and operates in a partially observable environment. The component's rate of degradation is modulated by the stochastic environment process, and the component fails when it is accumulated degradation first reaches a fixed threshold. Assuming periodic inspection of the component, the objective is to minimize the long‐run average cost per unit time of performing preventive and reactive replacements for two distinct cases. The first case examines instantaneous replacements and fixed costs, while the second considers time‐consuming replacements and revenue losses accrued during periods of unavailability. Formulated and solved are mixed state space, partially observable Markov decision process models, both of which reveal the optimality of environment‐dependent threshold policies with respect to the component's cumulative degradation level. Additionally, it is shown that for each degradation value, a threshold policy with respect to the environment belief state is optimal if the environment alternates between two states. The threshold policies are illustrated by way of numerical examples using both synthetic and real wind turbine data. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 395–415, 2015     

Efficient algorithms for flexible job shop scheduling with parallel machines

Job shop scheduling with a bank of machines in parallel is important from both theoretical and practical points of view. Herein we focus on the scheduling problem of minimizing the makespan in a flexible two-center job shop. The first center consists of one machine and the second has k parallel machines. An easy-to-perform approximate algorithm for minimizing the makespan with one-unit-time operations in the first center and k-unit-time operations in the second center is proposed. The algorithm has the absolute worst-case error bound of k − 1 , and thus for k = 1 it is optimal. Importantly, it runs in linear time and its error bound is independent of the number of jobs to be processed. Moreover, the algorithm can be modified to give an optimal schedule for k = 2 .     

The Management of Pakistan's Nuclear Arsenal

Pakistan, the fastest growing nuclear weapon state in the world, has established over the last decade a nuclear management system it holds to be “foolproof.” Despite the explosion of radical groups challenging the writ of the state, it dismisses concerns by critics that its nuclear weapons are not safe and secure as “preposterous” and an attempt to “malign” the state. This article examines Pakistan's nuclear management system in four functional areas: command-and-control, physical security, nuclear surety, and doctrine. It describes what is publicly known in each area, identifies areas of omission and inadequacy in each one, and examines several premises of the nuclear program the author considers to be unfounded. Comparing these deficiencies in Pakistan's nuclear management system to the current problems plaguing the US nuclear management system, the author concludes that complacency and unfounded confidence in the efficacy of such programs, if not addressed and corrected, could lead to a future nuclear catastrophe in South Asia.     

The Odyssey of the Comprehensive Nuclear-Test-Ban Treaty

This study examines the failures of the William J. Clinton and Barack Obama administrations to secure ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). It applies an integrated analytical framework for assessing treaty ratification that builds upon previous research in order to understand why the Clinton administration failed to achieve CTBT ratification in 1999 and why the Obama administration has so far failed to advance the treaty in the Senate. The study concludes that CTBT ratification, despite Obama administration pledges of support, remains highly unlikely. Finally, the study analyzes the common domestic political factors present in both cases and suggests areas for further research.     

Strength in Numbers: The Labour Government and the Size of the Polaris Force

Previous historical accounts have simplified the Labour government's decision to commission a four-boat strategic nuclear deterrent, or ‘Polaris force’, in early 1965. Utilising previously classified sources, this article shows that a number of key strategic concerns led the decision-making process. Nevertheless, broader economic and diplomatic considerations were also important in determining the size of the Polaris force. A tremendous balance of payments deficit and ongoing debates regarding levels of conventional and nuclear involvement in NATO certainly influenced the government's final decision. Moreover, competing strategic and economic interests resulted in continued debate throughout the decision-making process.     

Book Reviews

The purpose of this article is to analyse British strategic nuclear targeting between 1974 and 1979, prior to the successful completion of the sophisticated modification to Polaris submarine-missile system codenamed Chevaline. It will use as its starting point the parameters for UK strategic nuclear targeting, and the foundation of the ‘Moscow Criterion’, prior to the deployment of Britain's Polaris submarines which began in 1968. It will then discuss the recommendation by the Chiefs of Staff to retarget Polaris in 1975/76 and the implications of that recommendation in terms of the British approach to strategic nuclear deterrence. The article will conclude with an assessment of these retargeting decisions on the decision to replace Polaris with the US Trident system in 1980.