An inventory problem with obsolescence

A stochastic single product convex cost inventory problem is considered in which there is a probability, π_j, that the product will become obsolete in the future period j. In an interesting paper, Barankin and Denny essentially formulate the model, but do not describe some of its interesting and relevant ramifications. This paper is written not only to bring out some of these ramifications, but also to describe some computational results using this model. The computational results show that if obsolescence is a distinct possibility in the near future, it is quite important that the probabilities of obsolescence be incorporated into the model before computing the optimal policies.     

Production-location problems

The joint problems of determining the optimal plant location and optimal input mix and plant size are addressed. The interrelationship between input substitutability and plant location is stressed. Conditions under which the location problem can be separated from the determination of the optimal input mix are developed for a number of problem variations. The stability of the optimal location in the face of changes in problem parameters is also discussed. It is demonstrated that consideration of input substitutability often makes the resulting problem no more difficult to solve than problem formulations in which the inherent input substitutability is ignored.     

Optimizability of utility and value functions

For more than a decade, multiattribute utility/value theory and multiobjective mathematical programming have offered different approaches to similar problems. Unfortunately, the two areas have developed with little interaction in spite of their common aims. We consider the use of utility/value functions in a mathematical programming framework, and demonstrate that these functions often possess desirable properties from an optimization point of view. We conclude that a hybridization of approaches is more viable than is perhaps commonly assumed.     

A note on the optimality conditions for the bilevel programming problem

A counterexample is given to demonstrate that previously proposed necessary conditions for the bilevel programming problem are not correct. An interpretation of the difficulty is given by appealing to a “theorem of alternative” result presented in the original work.     

Mitigation of the blast load effects on a building structure using newly composite structural configurations

In this study, a nonlinear three-dimensional hydrocode numerical simulation was carried out using AUTODYN-3D to investigate the effect of blasting of a high explosive material (TNT) against several configurations of the composite structure. Several numerical models were carried out to study the effect of varying the thickness of the walls and the effect of adding an air layer or aluminum foam layer inside two layers of concrete in mitigating the effect of blast waves on the structure walls. The results showed that increasing the thickness of walls has a good effect on mitigating the effect of blast waves. When a layer of air was added, the effect of blast waves was exaggerated, while when a layer of aluminum foam was added the blast wave effects were mitigated with a reasonable percentage.     

Short-term retrenchment planning in hierarchical manpower systems

We address the issue of short-term retrenchment planning required of organizations that are phasing down their manpower levels at rates faster than are allowed by natural attrition. Specifically, the problem we study is as follows: given the initial and target grade populations in a hierarchical manpower system at the end of a finite time horizon and the per-period rate of natural attrition for each grade, find a stationary manpower policy that minimizes the maximum per-period rate of retrenchment across all the grades over all stationary policies that yield the target grade populations at the end of the horizon. Because the problem is a nonconvex, nonseparable, nonlinear program, we develop a heuristic in which the promotion proportions of all the grades are successively fixed, starting from the lowest grade. We prove optimality of the heuristic policy in three nontrivial situations. In a computational experiment, in 135 out of 150 randomly generated instances (i.e., in 90% of the cases), the heuristic yielded a solution that was as good or better than that yielded by a benchmark computer program that solves the present problem as a nonlinear program. Further, the average computational time under the heuristic was an order of magnitude less than that under the program. © 1995 John Wiley & Sons, Inc.     

A suboptimality bound for permutation policies in single machine stochastic scheduling

A general class of single machine stochastic scheduling problems incorporating precedence constraints is modelled as a family of competing Markov decision processes. A bound on the optimal return yields a suboptimality bound for permutation policies. This in turn leads to a generalised “used better than new” principle as a (highly intuitive) sufficient condition for the optimality of a permutation policy in the class of all (preemptive) policies. © 1995 John Wiley & Sons, Inc.     

Decision costs in the intelligence cycle

John Terraine, The Smoke and the Fire: Myths and Anti‐Myths of War 1861–1945. London: Sidgwick &; Jackson, 1980. Pp. 240; £8.95.

Stephen Roskill, Admiral of the Fleet: Earl Beatty. London: Collins,1980. Pp. 430; £12.95.

Peter and Leni Gillman, ’Collar the Lot’. How Britain Interned and Expelled its Wartime Refugees. London: Quartet Books, 1980. Pp. 314; £8.95.

Frederic A. Bergerson, The Army Gels An Air Force: Tactics of Insurgent Bureaucratic Politics. Baltimore and London: The Johns Hopkins University Press, 1980. Pp. xiii + 216; £8.50.

Christoph Bertram (ed), Prospects of Soviet Power in the 1980s. London: Macmillan, and IISS, 1980. Pp. 126; £15.

James M. Roherty (ed.), Defense Policy Formulation: Towards Comparative Analysis. Durham, NC: Carolina Academic Press, 1980. Pp. 315; $14.95.

Franklyn Griffiths and John C. Dolanyi, The Dangers of Nuclear War. Toronto: University of Toronto Press, 1979. $15.00.

Kenneth Mackenzie, Turkey under the Generals. London: Institute for the Study of Conflict, Conflict Studies. Number 126, January 1981. Pp. 31.     

India and Israel: emerging partnership

The absence of formal diplomatic relations between India and Israel from India's hesitant recognition of Israel in 1950 and the establishment of full relations in January 1992, was the result of a complex interplay between two sets of tensions. The first involved the Arab–Israeli dispute, and India's sympathies with a post-colonial Arab world and with the Non-Aligned Movement; the second involved accommodating Muslim opinion within India. Normalization has proceeded more strongly as the growth of Hindu nationalism has weakened Muslim leverage on Indian foreign policy.