Note: Open-shop scheduling with release dates to minimize maximum lateness

We present the first polynomial-time algorithm for an open-shop problem with unit execution times, arbitrary release dates, and due dates. The objective is to minimize maximum lateness. © 1995 John Wiley & Sons, Inc.     

The parallel machine min-max weighted absolute lateness scheduling problem

Given a set of jobs, a processing time and a weight for each job, several parallel and identical machines, and a common due date that is not too early to constrain the scheduling decision, we want to find an optimal job schedule so as to minimize the maximum weighted absolute lateness. We show that this problem is NP-complete even for the single-machine case, and is strongly NP-complete for the general case. We present a polynomial time heuristic for this problem and analyze its worst-case performance. Empirical testing of the heuristic is reported, and the results suggest that the performance is asymptotically optimal as the number of jobs tends to infinity. © 1994 John Wiley & Sons, Inc.     

Equipment replacement under technological change

For infinite-horizon replacement economy problems it is common practice to truncate the problem at some finite horizon. We develop bounds on the error due to such a truncation. These bounds differ from previous results in that they include both revenues and costs. Bounds are illustrated through a numerical example from a real case in vehicle replacement. © 1994 John Wiley & Sons, Inc.     

A bayesian approach to environmental stress screening

The article presents a Bayesian analysis for the environmental stress screening problem. The decision problem of deriving optimal stress screen durations is solved. Given a screen duration, the optimal stress level can also be determined. Indicators of the quality of a screen of any duration are derived. A statistical model is presented which allows a posterior density for the rate of early failures of the production process to be calculated. This enables the user to update his opinion about the quality of the process. © 1994 John Wiley & Sons, Inc.     

Characterizing the barlow-wu structure functions

Various mathematical models for multistate systems have been proposed in the literature. Among them the model introduced by Barlow and Wu is the one most intimately related to that of binary systems; hence the Barlow-Wu class possesses many nice properties inherited from the binary systems. In this article we obtain several characterization results for multistate systems, which closely relate the Barlow-Wu class to other classes of multistate systems. The characterizations we obtained originate from the invariance properties of the Barlow-Wu functions, and are easy to apply in verifying whether a particular model is of the Barlow-Wu type. © 1994 John Wiley & Sons, Inc.     

The parallel replacement problem with demand and capital budgeting constraints

A generalized parallel replacement problem is considered with both fixed and variable replacement costs, capital budgeting, and demand constraints. The demand constraints specify that a number of assets, which may vary over time, are required each period over a finite horizon. A deterministic, integer programming formulation is presented as replacement decisions must be integer. However, the linear programming relaxation is shown to have integer extreme points if the economies of scale binary variables are fixed. This allows for the efficient computation of large parallel replacement problems as only a limited number of 0–1 variables are required. Examples are presented to provide insight into replacement rules, such as the “no‐splitting‐rule” from previous research, under various demand scenarios. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 40–56, 2000     

French Arms Exports and Intrastate Conflicts: An Empirical Investigation

The aim of this article is to evaluate how French Major Conventional Weapons (MCW) exports impact on the conflict intensity of recipient countries. The recent increase in French arms exports seems to contradict the French political discourse on the promotion of regional stability. We run zero-inflated ordered probit model in order to analyze the role of the arms trade on the intensity of civil conflicts in 144 countries from 1992 to 2014, using SIPRI and UCDP/PRIO data. Our results suggest that French MCW exports tended not to exacerbate intrastate conflicts during this period. This finding is robust to changes in the empirical framework. We propose two lines of explanations: France seems to be prone to choosing partners that respect human rights and selling more ‘defense-oriented’ MCW than the rest of the world.     

Joining by Number: Military Intervention in Civil Wars

Understanding why and when states militarily intervene in civil wars is crucial. Intervention can increase civil wars’ severity and the strategies employed in civil wars are shaped by the possibility of military intervention. This article argues that potential military interveners react to information revealed about warring parties’ intentions and relative power. Without revealed information, potential military interveners are unlikely to reconsider their initial decision to remain out of the war. Revealed information causes non-belligerent states to update their expectations about the trajectory of the civil war causing them, at times, to change their calculus about the benefits of belligerency and thus intervene. This helps explain why civil wars spread and when they do so. This explanation is tested using generalised estimating equations on a new data-set of unexpected events for the civil wars in the Correlates of War Intrastate War and PRIO Armed Conflict data-sets.     

Assessment of machine tool reliability using a proportional hazards model

In this article we present a proportional hazards model for describing machine tool failures. The model enables us to describe the effect of aging as well as the effect of the machining environment on tool life. We discuss inference for the model and show that computable results can be obtained in a fully Bayesian analysis by using approximation techniques. We illustrate the usefulness of our model by applying it to some actual data on machine tool failures.     

Opportunity-based age replacement: Exponentially distributed times between opportunities

This article gives a full analysis of a component-replacement model in which preventive replacements are only possible at maintenance opportunities. These opportunities arise according to a Poisson process, independently of failures of the component. Conditions for the existence of a unique average optimal control limit policy are established and an equation characterizing the optimal policy and minimal average costs is derived. An important result is that the optimal policy can be described as a so-called one-opportunity-look-ahead policy. Such policies play an important role as heuristics in more general models. It is shown that there is a correspondence with the well-known age-replacement model, which can be considered as an extreme case of the model. Finally, some numerical results are given.