Modeling and analysis of uncertain time‐critical tasking problems

This paper describes modeling and operational analysis of a generic asymmetric service‐system situation in which (a) Red agents, potentially threatening, but in another but important interpretation, are isolated friendlies, such as downed pilots, that require assistance and “arrive” according to some partially known and potentially changing pattern in time and space; and (b) Reds have effectively limited unknown deadlines or times of availability for Blue service, i.e., detection, classification, and attack in a military setting or emergency assistance in others. We discuss various service options by Blue service agents and devise several approximations allowing one to compute efficiently those proportions of tasks of different classes that are successfully served or, more generally, if different rewards are associated with different classes of tasks, the percentage of the possible reward gained. We suggest heuristic policies for a Blue server to select the next task to perform and to decide how much time to allocate to that service. We discuss this for a number of specific examples. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.     

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.     

Aiming to Break Will: America's World War II Bombing of German Morale and its Ramifications

This article examines the implications of the proliferation of cyberwarfare capabilities for the character and frequency of war. Consideration of strategic logic, perceptions, and bargaining dynamics finds that the size of the effect of the proliferation of cyberwarfare capabilities on the frequency of war will probably be relatively small. This effect will not be constant across all situations; in some cases the advent of cyberwarfare capabilities may decrease the likelihood of war. On the other hand, the use of computer network attack as a brute force weapon will probably become increasingly frequent.     

Disregarding the Bear: How US Intelligence Failed to Estimate the Soviet Intervention in the Egyptian–Israeli War of Attrition 1

This article analyzes the main factors that contributed to the failure of the US intelligence community to alert against Soviet intentions and the intervention in the Egyptian–Israeli War of Attrition in 1969–70. Based on fresh archival sources, this research describes the US intelligence conception concerning the USSR; explains the crystallization of the intelligence estimate on the probability of Soviet intervention in 1970; deals with the intelligence data that were acquired but eventually ignored; and concludes with several plausible explanations for the intelligence blunder.     

Bounded flexibility in days‐on and days‐off scheduling

This article presents a flexible days‐on and days‐off scheduling problem and develops an exact branch and price (B&P) algorithm to find solutions. The main objective is to minimize the size of the total workforce required to cover time‐varying demand over a planning horizon that may extend up to 12 weeks. A new aspect of the problem is the general restriction that the number of consecutive days on and the number of consecutive days off must each fall within a predefined range. Moreover, the total assignment of working days in the planning horizon cannot exceed some maximum value. In the B&P framework, the master problem is stated as a set covering‐type problem whose columns are generated iteratively by solving one of three different subproblems. The first is an implicit model, the second is a resource constrained shortest path problem, and the third is a dynamic program. Computational experiments using both real‐word and randomly generated data show that workforce reductions up to 66% are possible with highly flexible days‐on and days‐off patterns. When evaluating the performance of the three subproblems, it was found that each yielded equivalent solutions but the dynamic program proved to be significantly more efficient. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 678–701, 2013     

The Kargil Conflict: Waging War in the Himalayas

In 1999 India and Pakistan engaged in a limited war in the Himalayan peaks of Kashmir. Pakistani irregulars occupied territory in the Indian-held district of Kargil. A campaign that lasted 74 days and cost each side more than 1,000 casualties concluded with India in control of the commanding heights around Kargil. The conflict exposed flaws in the Indian armed forces as well as enduring truths of combat in the high mountains. Political constraints combined with the unforgiving environment and a determined enemy to diminish India's military advantage. Transition from counterinsurgency to high-intensity combat in the Himalayas proved to be a daunting task. Early failure was only overcome through innovation and adaptation to the environment. Specialised forces, unconventional techniques and the focused application of overwhelming firepower ultimately secured victory.     

MULTIPARTY DEMOCRACY IN TANZANIA

This article attempts to understand the manner in which the notion of good governance has been applied in the United Republic of Tanzania. In 1989, the World Bank issued a document which argued that Africa's development problems were in essence a crisis of governance. This became the basis for the imposition of conditionalities in order to establish liberal democratic governments. More than a decade later, good governance still dominates the donor agenda, which is reminiscent of the heyday of colonialism and the civilising mission that thrust Africa into the orbit of the European world, albeit as a ‘dark continent’. Although Tanzania has escaped the more overt political turmoil that plagued neighbouring countries, the country appears to be open to inter-ethnic rivalry due largely to Zanzibar, the site of the greatest opposition to the ruling party, in power since independence. The challenge is to deal with the dysfunctional economy and to meet the growing demands of its population for adequate social services. The ideal of self-reliance espoused by Nyerere is no longer a choice but a necessity.