Scheduling parallel machines with inclusive processing set restrictions

We consider the problem of assigning a set of jobs to different parallel machines of the same processing speed, where each job is compatible to only a subset of those machines. The machines can be linearly ordered such that a higher‐indexed machine can process all those jobs that a lower‐indexed machine can process. The objective is to minimize the makespan of the schedule. This problem is motivated by industrial applications such as cargo handling by cranes with nonidentical weight capacities, computer processor scheduling with memory constraints, and grades of service provision by parallel servers. We develop an efficient algorithm for this problem with a worst‐case performance ratio of + ε, where ε is a positive constant which may be set arbitrarily close to zero. We also present a polynomial time approximation scheme for this problem, which answers an open question in the literature. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

A location‐inventory model with lateral transshipments

We study an infinite horizon periodic stochastic inventory system consisting of retail outlets and customers located on a homogenous line segment. In each period, the total demand, generated by the customers on the line, is normally distributed. To better match supply and demand, we incorporate lateral transshipments. We propose a compact model in which the strategic decisions—the number and locations of retail outlets—are determined simultaneously with the operational decisions—the inventory replenishment and transshipment quantities. We find the optimal balance between the risk‐pooling considerations, which drive down the optimal number of retail outlets, and lateral transshipments, which drive up the optimal number of retail outlets. We also explore the sensitivity of the optimal number of retail outlets to various problem parameters. This article presents a novel way of integrating lateral transshipments in the context of an inventory‐location model. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

ARMY RE‐ENLISTMENT DURING OIF/OEF: BONUSES,DEPLOYMENT, AND STOP‐LOSS

In 2004, stretched by wartime deployments, the US Army countered declining retention by increasing re‐enlistment bonuses and implementing stop‐loss to prevent soldiers from separating at the end of their enlistment. We estimate the effects of bonuses, deployment, and stop‐loss on re‐enlistment between FY 2002 and 2006. We estimate that the baseline propensity to re‐enlist fell by 20%. However, we find that deployed soldiers are more likely to re‐enlist and that the estimated effects of re‐enlistment bonuses are similar to those estimated in peacetime. We evaluate the reasons for our findings, and calculate the cost effectiveness of re‐enlistment bonuses.     

Themes in defence manpower economics and challenges for the future

Raising and maintaining military forces have posed enormous challenges for the United States and its allies. Economists have made significant contributions to understanding of how to recruit and manage such forces. This paper highlights key past contributions and discusses challenges for future research. Rapid changes in the roles and missions of military personnel, technology, and the civilian labor market pose serious challenges for future military manpower policy and will challenge economists to develop new approaches to military recruiting and personnel management. Yet the body of past research can continue to provide insight and guidance in making decisions about defense manpower.     

WARFARE IN A NEW DOMAIN: THE ETHICS OF MILITARY CYBER-OPERATIONS

While most normative evaluations of military cyber-operations have emerged from the legal community, this article assesses the legitimacy of such operations from a philosophical-ethical perspective. After reviewing the relationship between rights forfeiture and the jus ad bellum and jus in bello criteria of the just war tradition, it applies these criteria to several aspects of cyber-operations, including responses to cyber-activities, the use of cyber-capabilities affecting combatants and civilians, and the use of these capabilities by contractors. Finally, it briefly addresses the legitimacy of limiting rights to privacy and anonymity in service of preventing cyber-harm.     

Military Expenditures,Income Inequality,Welfare and Political Regimes: A Dynamic Panel Data Analysis

The goal of this paper is to investigate the relationship between type of welfare regimes and military expenditures. There is a sizeable empirical literature on the development of the welfare state and on the typology of the welfare regimes. There appear to be, however, no empirical studies that examine welfare regimes with special attention to military spending. This study aims at providing a comprehensive analysis on the topic by considering several different welfare regime typologies. To do so, we use dynamic panel data analysis for 37 countries for the period of 1988–2003 by considering a wide range of control variables such as inequality measures, number of terrorist events, and size of the armed forces. We also replicate the same analyses for the political regimes. Our findings, in line with the literature, show that there is a positive relationship between income inequality and share of military expenditures in the central government budget, and that the number of terrorist events is a significant factor that affects both the level of military expenditure and inequality. Also, the paper reveals a significant negative relationship between social democratic welfare regimes and military expenditures.     

Bioprotection of facilities

The anthrax attacks of 2001 energized research directed toward reducing health consequences from airborne contaminants by augmenting current heating ventilation and air-conditioning (HVAC) systems. Even during peacetime, interest will continue in improving HVAC components to reduce biocontaminants associated with sick building syndrome. Current HVAC design uses numerical simulation methods of ordinary differential equations to predict approximate performance. The authors show that state-space Laplace Transform calculations actually solve the underlying differential equations and yield algebraic expressions that provide new insight. To sharpen the arguments in favor of this methodology, attention is restricted to improving existing HVAC systems to increase protection from an external release of hazardous particulates. By nearly eliminating the need for dynamical simulation, the resulting methods can be applied to far more complex HVAC designs with little additional computational effort. The new methods reduce the time required for computation by three orders of magnitude. These algebraic methods also can be extended to disparate technical problems including internal particulate release, gas masks, and designing new protective buildings.