Multi-item service constrained (s,S) policies for spare parts logistics systems

Many organizations providing service support for products or families of products must allocate inventory investment among the parts (or, identically, items) that make up those products or families. The allocation decision is crucial in today's competitive environment in which rapid response and low levels of inventory are both required for providing competitive levels of customer service in marketing a firm's products. This is particularly important in high-tech industries, such as computers, military equipment, and consumer appliances. Such rapid response typically implies regional and local distribution points for final products and for spare parts for repairs. In this article we fix attention on a given product or product family at a single location. This single-location problem is the basic building block of multi-echelon inventory systems based on level-by-level decomposition, and our modeling approach is developed with this application in mind. The product consists of field-replaceable units (i.e., parts), which are to be stocked as spares for field service repair. We assume that each part will be stocked at each location according to an (s, S) stocking policy. Moreover, we distinguish two classes of demand at each location: customer (or emergency) demand and normal replenishment demand from lower levels in the multiechelon system. The basic problem of interest is to determine the appropriate policies (s_i S_i) for each part i in the product under consideration. We formulate an approximate cost function and service level constraint, and we present a greedy heuristic algorithm for solving the resulting approximate constrained optimization problem. We present experimental results showing that the heuristics developed have good cost performance relative to optimal. We also discuss extensions to the multiproduct component commonality problem.     

Pareto-optimality in classical inventory problems

In this paper the inventory problem with backorders both deterministic and stochastic is studied using trade-off analysis in the context of vector optimization theory. The set of Pareto-optimal solutions is geometrically characterized in both the constrained and unconstrained cases. Moreover, a new way of utilizing Pareto-optimality concepts to handle classical inventory problems with backorders is derived. A new analysis of these models is done by means of a trade-off analysis. New solutions are shown, and an error bound for total inventory cost is provided. Other models such as multi-item or stochastic lead-time demand inventory problems are addressed and their Pareto-optimal solution sets are obtained. An example is included showing the additional applicability of this kind of analysis to handle parametric problems. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 83–98, 1998     

Scheduling peacetime rotation of Pakistan army units

Because Pakistan has varying climates and terrains, the Pakistan Army rotates its units between peacetime locations so that no unit endures inequitable hardship or enjoys unfair advantage. Army policy specifies strict constraints on unit rotations, such as the length of a unit's stay in any location, the number of units moving at any time, and the allowable replacements for any moving unit. Scheduling rotations manually in accordance with these rules, as is currently practiced, is extremely difficult and time consuming. This article presents an integer programming model that finds feasible, minimum-cost schedules for the Pakistan Army's desired planning horizons. The model also ensures that the units are positioned at the end of the planning horizon so that feasible schedules exist for future planners. The model is implemented with commercially available optimization software. Schedules are obtained for realistic test problems in less than an hour on a personal computer. © 1995 John Wiley & Sons, Inc.     

Target Analysis of Shining Path Insurgents in Peru: An Example of US Army Psychological Operations

This article analyzes the assumptions of US and Peruvian military personnel regarding insurgent susceptibilities to psychological operations in 1988. The discussion is based on both archival material and the experiences of the author, who was a member of the joint US-Peruvian team. The paper provides insight into the workings of US Army psychological operations as they were conducted in the 1980s and outlines both the strengths and weaknesses of the approach taken.     

Conflict circuit breakers in the Great Lakes Region of Africa

Conflict resolution in the African Great Lakes Region has been linked to the protocols and projects agreed upon at the Second International Conference on the Great Lakes Region (ICGLR). The ICGLR created a continental-wide framework of conflict circuit breakers focused on resolving the structural and surface situational causes of the 1996 to 2003 armed conflicts that drew in at least six nations and destabilised the entire region. The implementation of these protocols and projects will serve as a test for the African Great Lakes Region to move away from conflict and into a cooperation and development phase; however, the effort to bring peace, stability and development will face obstacles not only in the security sector, but also in developing infrastructure, civil society, and good governance. In summary, this article contends that peace in the Great Lakes Region will depend equally on two factors: internal governance and building civil society institutions, and focused regional interlocking circuit-breaking institutions.     

THE FRAGILE TRADITION OF NUCLEAR RESTRAINT

The Tradition of Non-Use of Nuclear Weapons by T.V. Paul. Stanford University Press, 2009. 319 pages, $29.95.