Organizations that utilize fleets of expensive repairable equipment are faced with numerous challenges related to the specification of maintenance policies and the allocation of maintenance resources. The associated maintenance decisions can have a drastic impact on fleet performance. Due to the significant acquisition costs associated with the components that comprise the units of equipment in the fleet, cannibalization is often used in the absence of available spare parts to enable fleet maintenance managers to satisfy fleet performance constraints such as readiness requirements. This research is focused on the development and analysis of a closednetwork, discrete-event simulation model that is used to assess the impacts of cannibalization, small spare parts inventories and maintenance-induced damage on a fleet of systems. Using numerical examples, we demonstrate the comparison between cannibalization and the investment in limited spare parts inventories. We evaluate fleet performance using average readiness and total maintenance cost. Specifically, we demonstrate that investments in spare parts inventories can reduce the need for and value of cannibalization. However, our results also support the use of cannibalization as a low-cost alternative to investing in expensive spare parts. We also explore the impact of damage induced by maintenance on fleet performance. Specifically, we demonstrate that maintenance-induced damage can reduce the benefit of cannibalization while drastically increasing maintenance expenditures.
Ranking sports teams in the absence of full round-robin tournaments is big business, especially for NCAA Division I-A college football. The Bowl Championship Series awards millions of dollars each year to the conferences whose teams are awarded bids. We formulated the sports-team-ranking problem as a customizable quadratic-assignment problem. Decision makers can tailor our model to suit their personal definitions of the degree of victory for each game played and the relative distance between ranking positions. We developed a parameter-section procedure for determining these customized values and executed it using the 2004 college football season. Because the problem size is so large, we developed a heuristic solution procedure based on a genetic algorithm and local search techniques. This heuristic performs well on a special problem instance in which we can easily identify the optimal ranking. To examine the behavior of our approach, we implemented the heuristic for the 1999 through 2004 college football seasons. We concluded that our approach works best when the margin of victory of individual games is not considered, the location of games is considered, and the date of games is considered. Finally, we evaluated how our approach would have weighed in on several recent controversies in NCAA Division I-A college football and found that our approach generally agrees with traditional schools of thought regarding these controversies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.