Resource allocation with lumpy demand: To speed or not to speed?

In the classical EPQ model with continuous and constant demand, holding and setup costs are minimized when the production rate is no larger than the demand rate. However, the situation may change when demand is lumpy. We consider a firm that produces multiple products, each having a unique lumpy demand pattern. The decision involves determining both the lot size for each product and the allocation of resources for production rate improvements among the products. We find that each product's optimal production policy will take on only one of two forms: either continuous production or lot‐for‐lot production. The problem is then formulated as a nonlinear nonsmooth knapsack problem among products determined to be candidates for resource allocation. A heuristic procedure is developed to determine allocation amounts. The procedure decomposes the problem into a mixed integer program and a nonlinear convex resource allocation problem. Numerical tests suggest that the heuristic performs very well on average compared to the optimal solution. Both the model and the heuristic procedure can be extended to allow the company to simultaneously alter both the production rates and the incoming demand lot sizes through quantity discounts. Extensions can also be made to address the case where a single investment increases the production rate of multiple products. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

A bayes approach to quality control of an M/G/1 queue

This article provides a Bayes approach for the quality control of a production process which is defined by an M/G/1 queue. An inspection procedure which is jointly optimal from the queue's operational characteristics and quality-control perspectives is found using a queue-inspection renewal cycle analysis (with overall expected profit per unit time as the optimization objective). Numerical results are obtained, highlighting the relationships between quality control and (queue-like) production management.     

End of the cycle: assessing ETA’s strategies of terrorism

ABSTRACT

In May 2018, the Basque insurgent group Euskadi Ta Askatasuna (ETA) officially disbanded after a 60-year struggle. This inquiry assesses ETA’s violent campaigns using recent conceptual and theoretical advancements from the field of terrorism studies. Three conclusions concerning the group’s strategies of terrorism are advanced. First, ETA regularly targeted civilians to achieve goals other than coercing the Government of Spain; these objectives included outbidding rival separatist groups and spoiling negotiation processes. Second, ETA’s most rapid period of organizational growth occurred as the result of an aggressive terrorist campaign, demonstrating that civilian targeting can serve as a stimulus to rebel group recruitment. Finally, while terrorism did not advance ETA’s primary political objective of creating an independent Basque state, it did enable the group to assume a leading position within the radical Basque separatist movement, helping extend ETA’s lifespan and making the group an embedded actor within the contentious political processes surrounding the question of Basque self-determination. Collectively, these conclusions support recent theoretical findings arguing that non-state terrorism often enables insurgent groups to prolong their lifespans while paradoxically making it more difficult for them to advance their long-term political objectives.     

CHOOSING GENOCIDE: ECONOMIC PERSPECTIVES ON THE DISTURBING RATIONALITY OF RACE MURDER

An economic theory of genocide is presented with application to Rwanda‐1994. The theory considers ‘macro’ conditions under which an authority group chooses genocide and ‘micro’ conditions that facilitate the spread of genocide. From the macro perspective, a bargaining model highlights four rational explanations for an authority’s choice of genocide: prevention of loss of power, indivisibility, elimination of a persistent rival, and political bias. From the micro perspective, an evolutionary game model shows how supporters of genocide gain the upper hand in group dynamics over resisters and bystanders. The theory and application suggest that the conditions for genocide are not exceptional.     

Continuous quality production and machine maintenance

This paper formulates a problem of continuous quality production and maintenance of a machine. Quality is assumed to be a known function of the machine's (Markov diffusion process) degradation states. Applications to a specific quality function are used to obtain analytical solutions to an open-loop and feedback stochastic control maintenance problem.     

Quality control and the sales process

Product quality is emerging as a major strategic instrument for competition. The purpose of this article is to assess the effects of quality control on sales, and, vice versa, the effects of the sales process on quality control. A model relating quality control and the sales process (advertising, repeat purchase, and word-of-mouth effects) is developed to evaluate the above relationships. Two special cases, with degenerate and beta distribution for defect items in the production lot, are analyzed in detail. In the former case, analytical results for the optimal quality control schemes are obtained, whereas in the latter, efficient bounds are derived to search for the optimal scheme. It is shown, analytically and numerically, that the sales parameters have significant impact on whether more “stringent” or “tighter” quality control is warranted. Future research directions are also discussed.