
John A. Muckstadt: Research Interests My research interests lie in the areas of manufacturing systems, supply chain and logistics systems, production control and inventory theory and practice. The goal is to develop mathematical and simulation models to study the behavior of these systems and to identify optimal and effective operating policies. Presently we are working on several research problems. First, we have been studying supply chain problems in the process industries. These are large scale systems involving many production and distribution stages. There are several research objectives. We want to model the effect of uncertainty in these systems on production and distribution decisions. We also want to show how to quantify the economic benefits of collaboration in the systems. Finally, we are exploring methods for solving the largescale problems. This requires devising various types of aggregation and decomposition approaches for finding good, if not optimal, solutions. These activities are supported by the NSF and Aspen technology. Second, we are examining several socalled service parts problems. These are parts that are used to repair automobiles, aircraft, copying machines, computers, refinery equipment, etc. We are developing mathematical and simulation models that address a wide range of strategic, tactical, and operational issues faced in a variety of application areas. These systems are very large, consisting, in some instances, of thousands of stocking locations which provide access to hundreds of thousands of parts to customers. Some of the issues being studied are as follows: what should the topology of the network be; what parts should be stocked at each location to provide given levels of service; how should available stock be allocated throughout the resupply network; and, for repairable parts, how should repair facilities be sized, located, and operated. The goal is to develop computationally tractable methods for solving these problems. This research is sponsored by General Motors and XELUS. Third, we are examining a purely theoretical inventory control problem. A twoechelon system is being studied. Demands occur at the lowest level, called a retailer. If stock is on hand, the demand is satisfied; otherwise the demand is lost. The retailer locations periodically place orders on the central warehouse location, which, in turn, places orders on an external supplier. The central warehouse satisfies the retailer orders, if it can. There are replenishment lead times in the system. The goals of the research are to identify characteristics of an optimal policy, establish the behavior of cost functions, examine the effectiveness of simple orderupto policies, and to construct algorithms for finding solutions to the various optimization problems that have been constructed.
