Capacitated selection problem

Optimizing the selection of resources to accomplish a set of tasks involves evaluating the tradeoffs between the cost of maintaining the resources necessary to accomplish the tasks and the penalty cost associated with unfinished tasks. We consider the case where resources are categorized into types, and limits (capacity) are imposed on the number of each type that can be selected. The objective is to minimize the sum of penalty costs and resource costs. This problem has several practical applications including production planning, new product design, menu selection and inventory management. We develop a branch‐and‐bound algorithm to find exact solutions to the problem. To generate bounds, we utilize a dual ascent procedure which exploits the special structure of the problem. Information from the dual and recovered primal solutions are used to select branching variables. We generate strong valid inequalities and use them to fix other variables at each branching step. Results of tests performed on reasonably sized problems are presented. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 19–37, 1999     

Scheduling patients in an ambulatory surgical center

This paper presents a deterministic approach to schedule patients in an ambulatory surgical center (ASC) such that the number of postanesthesia care unit nurses at the center is minimized. We formulate the patient scheduling problem as new variants of the no‐wait, two‐stage process shop scheduling problem and present computational complexity results for the new scheduling models. Also, we develop a tabu search‐based heuristic algorithm to solve the patient scheduling problem. Our algorithm is shown to be very effective in finding near optimal schedules on a set of real data from a university hospital's ASC. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

NATO’s push into the Caucasus: geopolitical flashpoints and limits for expansion

The Caucasus has been a major flashpoint of contention between NATO and a resurgent Russia since the collapse of the Soviet Union. The rivalry saw the escalation of hostility in the region during the brief 2008 Russo-Georgian War where a NATO-backed Georgia challenged South Ossetia supported by the Russian military. In 2011, NATO officially recognised Georgia as a potential member, challenging Russia’s traditional sphere of influence in the Caucasus. Moscow says the Eastward expansion of NATO into the Baltics and to include Georgia as a member state is a method of containing a resurgent Russia. However, the former Soviet Republics of Ukraine, the Baltics and Georgia, maintain that Russia represents a threat to their sovereignty, as seen by the Russian support of the breakaway unrecognised Republics of South Ossetia and Abkhazia. A hostile rivalry between the Russian-backed Armenia and Azerbaijan, which is reliant upon NATO-member Turkey, intensifies the polarisation in the Caucasus.     

The selection allocation problem

The Selection Allocation Problem (SAP) is a single period decision problem which involves selecting profit‐maximizing (or cost‐minimizing) activities from various distinct groups, and determining the volume of those activities. The activities in each group are selected subject to the availability of that group's resource, which is provided by either pooling or blending raw inputs from several potential sources. Imbedded in the decision process is the additional task of determining how much raw input is to be allocated to each group to form the resource for that group. Instances of this problem can be found in many different areas, such as in tool selection for flexible manufacturing systems, facility location, and funding for social services. Our goal in this paper is to identify and exploit special structures in the (SAP) and use those structures to develop an efficient solution procedure. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 707–725, 1999