On testing for decreasing mean residual life ordering

We consider the problem of testing for the decreasing mean residual life ordering introduced in Kochar and Wiens [14]. We treat both the one-sample and two-sample problems. The limiting distributions of the proposed test statistics are derived. © 1993 John Wiley & Sons, Inc.     

General models for the supplier's all-unit quantity discount policy

The purpose of this article is to investigate some managerial insights related to using the all-unit quantity discount policies under various conditions. The models developed here are general treatments that deal with four major issues: (a) one buyer or multiple buyers, (b) constant or price-elastic demand, (c) the relationship between the supplier's production schedule or ordering policy and the buyers' ordering sizes, and (d) the supplier either purchasing or manufacturing the item. The models are developed with two objectives: the supplier's profit improvement or the supplier's increased profit share analysis. Algorithms are developed to find optimal decision policies. Our analysis provides the supplier with both the optimal all-unit quantity discount policy and the optimal production (or ordering) strategy. Numerical examples are provided. © 1993 John Wiley & Sons. Inc.     

A computationally efficient approach for determining inventory levels in a capacitated multiechelon production‐distribution system

The system under study is a single item, two‐echelon production‐inventory system consisting of a capacitated production facility, a central warehouse, and M regional distribution centers that satisfy stochastic demand. Our objective is to determine a system base‐stock level which minimizes the long run average system cost per period. Central to the approach are (1) an inventory allocation model and associated convex cost function designed to allocate a given amount of system inventory across locations, and (2) a characterization of the amount of available system inventory using the inventory shortfall random variable. An exact model must consider the possibility that inventories may be imbalanced in a given period. By assuming inventory imbalances cannot occur, we develop an approximation model from which we obtain a lower bound on the per period expected cost. Through an extensive simulation study, we analyze the quality of our approximation, which on average performed within 0.50% of the lower bound. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 377–398, 2000     

Leaderless Global Jihadism: The Paradox of Discriminate Violence

Jihadist violence is typically associated with being particularly indiscriminate. Often, as in variations of the ‘new terrorism’ thesis, this characteristic is proposed to correspond in some way to its other attributes such as its globalised, decentralised and ‘postmodern’ religious nature. Recent work appears to give more substance to such claims, by claiming to show a relationship between indiscriminate violence and decentralised group organisation. However, in this paper we show, based on an analysis of jihadist targeting in Western Europe and America from 2001 to 2013, that targeting choices by jihadists unconnected to organised militant groups have in fact been consistently more, rather than less discriminate in their targeting choices than their better-integrated peers. Drawing on this finding, as well as a broader reading of jihadist targeting discourses, we argue for a more complex understanding of the relationship between radicalisation, extremist ideology, decentralisation, and targeting choice.     

Military Expenditures and Natural Resources: Evidence from Rentier States in the Middle East and North Africa

It has been argued that the discovery of a new natural resource greatly increases the risk of conflict. This research aims to study the effect of natural resources on military spending, using the data from rentier states in the Middle East and North Africa (MENA) countries from 1987 to 2012. In considering the ‘resource curse,’ the types of natural resources matter. Our empirical results demonstrate that the ‘resource curse’ arising from the abundance of certain natural resources, particularly oil and forest resources, leads to increases in military spending. In contrast, the rent from coal and natural gas has a negative impact on military spending, while the rent from minerals has no impact on military spending, controlling for GDP growth and per capita income.     

Preemptive parallel‐machine scheduling with a common server to minimize makespan

We consider parallel‐machine scheduling with a common server and job preemption to minimize the makespan. While the non‐preemptive version of the problem is strongly NP‐hard, the complexity status of the preemptive version has remained open. We show that the preemptive version is NP‐hard even if there is a fixed number of machines. We give a pseudo‐polynomial time algorithm to solve the case with two machines. We show that the case with an arbitrary number of machines is unary NP‐hard, analyze the performance ratios of some natural heuristic algorithms, and present several solvable special cases. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 388–398, 2017     

Scheduling combat logistics force replenishments at sea for the US Navy

The Replenishment at Sea Planner (RASP) is saving the U.S. Navy millions of dollars a year by reducing fuel consumption of its Combat Logistics Force (CLF). CLF shuttle supply ships deploy from ports to rendezvous with underway U.S. combatants and those of coalition partners. The overwhelming commodity transferred is fuel, ship‐to‐ship by hoses, while other important packaged goods and spare parts are high‐lined, or helicoptered between ships. The U.S. Navy is organized in large areas of responsibility called numbered fleets, and within each of these a scheduler must promulgate a daily forecast of CLF shuttle operations. The operational planning horizon extends out several weeks, or as far into the future as we can forecast demand. We solve RASP with integer linear optimization and a purpose‐built heuristic. RASP plans Replenishment‐at‐Sea (RAS) events with 4‐hour (Navy watch) time fidelity. For five years, RASP has served two purposes: (1) it helps schedulers generate a daily schedule and animates it using Google Earth, and (2) it automates reports command‐to‐ship messages that are essential to keep this complex logistics system operating.     

The role and capabilities of major weapon systems transferred between 1950 and 2010: Empirical examinations of an arms transfer data set

Arms transfers provide exporters an avenue to provide security to other states while gaining economic benefits. Arms transfers provide importers an avenue to gain security without having to rely on alliances. Past research uses aggregate measures of the monetary or security value of major weapon system transfers without accounting for strategic differences in possible use in interstate and civil conflict. This article presents a data set on interstate transfers of major weapon systems between 1950 and 2010 building upon Stockholm Peach Research Institute’s Arms Trade Register with several improvements. First, it disaggregates land weapons and air weapons into categories reflecting their strategic capabilities. Second, model level characteristics (e.g. age, speed, and range) are drawn from Jane’s Defence sources. Additionally, the data set covers a larger range of time and states than previous data sets categorizing arms. To demonstrate the usefulness, this article first presents summary statistics of the data set and then replicates an earlier test to show that the effect of human rights and regime types on United States transfers differs across the categories of arms compared to alternative measures of arms transfers.     

Financial versus human resources in the Greek‐Turkish arms race: A forecasting investigation using artificial neural networks

This paper aims at forecasting the burden on the Greek economy resulting from the arms race against Turkey and at concentrating on the leading determinants of this burden. The military debt and the defence share of GDP are employed alternatively in order to approximate the measurement of the arms race pressure on Greece, and the method used is that of artificial neural networks. The use of a wide variety of explanatory variables in combination with the promising results derived, suggest that the impact on the Greek economy resulting from this arms race is determined, to a large, extent, by demographic factors which strongly favour the Turkish side. Prediction on both miltary debt and defence expenditure exhibited highly satisfactory accuracy, while the estimation of input significance, indicates that variables describing the Turkish side are often dominant over the corresponding Greek ones.