A mathematical model for generating the area of a drainage basin

This paper presents a mathematical model that yields the area drained by a naturally-occurring network of streams. The model is based on empirically derived relationships in the field of quantitative geomorphology and an assumption concerning the probabilistic nature of stream system formation. A wide range of model solutions is indicated, and the model is validated by comparing the results to statistics from actual stream systems.     

On a generalized bin-packing problem

In this paper we address a bin-packing problem which possesses a variety of modifications of the classic theme. Among these are bin-dependent chip weights, bin costs, and bin-dependent penalties for unused capacity. Lagrangian relaxations are employed in the context of a branch-and-bound framework in order to solve the problem after which substantial computational experience is provided.     

Developing production schedules which balance part usage and smooth production loads for just-in-time production systems

A mixed-model multilevel manufacturing facility running under a just-in-time (JIT) production system is controlled by setting the production schedule for the highest level in the facility, which is usually a mixed-model final assembly line. The schedule is set to achieve the goals of the organization, which under JIT are (1) to keep a constant rate of part usage, and (2) to maintain a smooth production load. In this article we extend earlier work in the literature, which focused on the first goal, by developing scheduling procedures which satisfy both goals. Properties of the resulting production schedules are analyzed and illustrative examples are presented.     

Evaluation of commonly used rules for detecting “steady state” in computer simulation

A definition of the problem of the initial transient with respect to the steady-state mean value has been formulated. A set of criteria has been set forth by which the efficaacy of any proposed rule may be assessed. Within this framework, five heuristic rules for predicting the approximate end of transiency, four of which have been quoted extensively in the simulation literature, have been evaluated in the M/M/1 situation. All performed poorly and are not suitable for their intended use.     

Rethinking Stability in South Asia: India,Pakistan, and the Competition for Escalation Dominance

India and Pakistan are currently engaged in a competition for escalation dominance. While New Delhi is preparing for a limited conventional campaign against Pakistan, Islamabad is pursuing limited nuclear options to deter India. Together, these trends could increase the likelihood of nuclear conflict. India, for example, might conclude that it can launch an invasion without provoking a nuclear reprisal, while Pakistan might believe that it can employ nuclear weapons without triggering a nuclear exchange. Even if war can be avoided, these trends could eventually compel India to develop its own limited nuclear options in an effort to enhance deterrence and gain coercive leverage over Pakistan.     

Dynamic proximity calculations for situation awareness

We apply dynamic proximity calculations (density and clustering) from dynamic computational geometry to a military application. The derived proximity information serves as an abstract view of a current situation in the battlefield that can help a military commander achieve situation awareness. We employ Delaunay triangulation as a computational tool in our framework, and study its dynamic update in depth. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

On the behavior and shape of mixture failure rates from a family of IFR Weibull distributions

Populations of many types of component are heterogeneous and often consist of a small number of different subpopulations. This is called a mixture and it arises in a number of situations. For example, a majority of products in industrial populations are mixtures of defective items with shorter lifetimes and standard items with longer lifetimes. It is a well‐known result that distributions with decreasing failure rates are closed under mixture. However, mixtures of distributions with increasing failure rates are not easily classifiable. If the subpopulations involved in the mixture have increasing failure rates, there might be some upward movement in the mixture and later a general downward pull towards the strongest component. Little work has been done in describing the shape of mixture failure rates when all subpopulations do not have decreasing failure rate. In this paper, we present general results that describe the shape and behavior of a failure rate of a mixture obtained from two Weibull subpopulations with strictly increasing failure rates. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004