A nation-in-the-making,in arms: control of force,strategy and the Ukrainian Volunteer Battalions

At the core of waging war and strategy is the creation, control and use of force. This article investigates the volunteer battalions that mobilized in Ukraine during the spring of 2014. It contextualizes the volunteer phenomenon and focuses on the state strategies to establish control over these militias. As ambiguous entities arising from a situation characterized by rapid social change – revolution and war – the volunteer battalions threatened existing hierarchies and questioned state authority. The situation was exacerbated by the war, which deviated from the expectations of Ukrainian combatants and Western military observers alike. The state nevertheless enjoyed a modicum of success in reining in the militias through four strategies of undermining, co-option, incorporation and coercion. While predominantly integrated into a more rigid category of paramilitary forces, the volunteers continue to play a role in both the Ukrainian society and security sector to the unforeseeable future.     

Optimal sequential replenishment of ships during combat

A carrier battle group is operating in an area where it is subject to attack by enemy aircraft. It is anticipated that air raids will occur in large waves. The uncertain time between raids is available for the replenishment of supplies. We consider the problem of how best to schedule ammunition replenishment during this period. The theory of Gittins indices provides the technical background to the development of a range of models which yield a hierarchy of index-based heuristics for replenishment. One such heuristic is assessed computationally in a more realistic scenario than is explicitly allowed for by the models.     

Inventory rotation policies for slow moving items

In this article we present a stochastic model for determining inventory rotation policies for a retail firm which must stock many hundreds of distinctive items having uncertain heterogeneous sales patterns. The model develops explicit decision rules for determining (1) the length of time that an item should remain in inventory before the decision is made on whether or not to rotate the item out of inventory and (2) the minimum sales level necessary for retaining the item in inventory. Two inventory rotation policies are developed, the first of which maximizes cumulative expected sales over a finite planning horizon and the second of which maximizes cumulative expected profit. We also consider the statistical behavior of items having uncertain, discrete, and heterogeneous sales patterns using a two-period prediction methodology where period 1 is used to accumulate information on individual sales rates and this knowledge is then used, in a Bayesian context, to make sales predictions for period 2. This methodology assumes that over an arbitrary time interval sales for each item are Poisson with unknown but stationary mean sales rates and the mean sales rates are distributed gamma across all items. We also report the application of the model to a retail firm which stocks many hundreds of distinctive unframed poster art titles. The application provides some useful insights into the behavior of the model as well as some interesting aspects pertaining to the implementation of the results in a “real-world” situation.     

A generalized model for the economic design of x̄control charts for production systems with increasing failure rate and early replacement

This article generalizes the model for the economic design of x̄-control charts of Duncan [4], starting from the more recent papers of Lorenzen and Vance [8] and Banerjee and Rahim [3]. The classical model of Duncan [4] and its several extensions including the unified model of Lorenzen and Vance [8] assumed exponentially distributed in-control periods and provided uniform sampling schemes. Banerjee and Rahim [3], however, assumed a Weibull-distributed in-control period having an increasing failure rate and used variable sampling intervals. The present article is an extension of the work of Banerjee and Rahim [3], where a general distribution of in-control periods having an increasing failure rate is assumed and the possibility of age-dependent repair before failure is considered. Several different truncated and nontruncated probability models are chosen. It is proposed that economic benefits can be achieved by adopting a nonuniform inspection scheme and by truncating a production cycle when it attains a certain age. Numerical examples are presented to support this proposition. Finally, the effect of model specification in the choice of failure mechanism is investigated. © 1993 John Wiley & Sons, Inc.     

Some comments on the optimal assembly problem

It is shown that two recent results of Baxter and Harche [1] on monotone and balanced optimal assemblies hold only under conditions that are more restrictive than those originally proposed by the authors. We describe such additional conditions, illustrate why they are needed, and establish their sufficiency. We also consider a recent result by Malon [11] and demonstrate that, while the result itself is correct, its two proofs were incomplete. A complete proof of an extension of the result is then suggested. © 1995 John Wiley & Sons, Inc.     

A replacement model with overhauls and repairs

This article generalizes the classical periodical replacement model with minimal repair by considering the effect of the overhaul, which is assumed to be able to rejuvenate the system. The generalization is based on the notion of the virtual age of a system introduced by Kijima, Morimura, and Suzuki [“Periodical Replacement Problem without Assuming Minimal Repair,” European Journal of Operational Research, 37 , 194–203 (1988)]. © 1995 John Wiley & Sons, Inc.     

Optimal force mix in heterogeneous combat

This article presents models for determining the optimum number of Red weapons required to win a heterogeneous combat in which m(m> 1) types of Red weapons face a single type of Blue weapon under a newly defined termination policy. Red aims at either minimizing the total cost or maximizing the aggregated remaining force strength. Kuhn-Tucker and simulated annealing techniques are used for obtaining the optimal solution. The methodology is illustrated by analysing heterogeneous combat to determine (i) the feasibility of introducing new types of weapons and (ii) the number of weapons required to win if a specific type of weapon, say infantry, dominates. © 1995 John Wiley & Sons, Inc.     

Single-machine scheduling of stochastic jobs subject to deterioration or delay

N jobs are available for processing by a single machine. Jobs make (stochastic) progress while being processed but deteriorate while awaiting processing. The pioneering work of Browne and Yechiali, who developed scheduling policies for such models, is extended (i) to incorporate a precedence relation on the job set, delimiting the class of admissible policies, and (ii) to preemptive scheduling models. For the latter, we demonstrate that under appropriate conditions there is an optimal policy which is nonpreemptive. This is also achieved for a class of preemptive models in which processing generates delays for waiting jobs. A single class of algorithms is shown to generate optimal policies for many of the problems considered. © 1992 John Wiley & Sons, Inc.