Generalized Optimization Modeling for Defense Capital Planning and Equipment Replacement.

Recurring issues for Navy and DoD analysts are decisions on the upgrade, purchase, and retirement of equipment with high capital cost and long useful life. Since the PHOENIX model was developed in the late eighties a number of theses addressing different equipment procurement and modernization problems have been written at the Naval Postgraduate School. Those models have a common thread of purpose data, and methods that suggest the possibility of building a common model subsuming those previous efforts. The model developed is a mixed-integer linear program written in GAMS, and its most appealing characteristic is the spreadsheet application that allows the user to enter data, solve the model, analyze its output, enter user feedback in the process of finding a new solution, and also to manage a collection of candidate solutions. With this approach difficulties are hidden from the user who interacts only with the spreadsheet and does not have to build his own model. The combination of a generic model and the visual programming capability of the spreadsheet provides the user with a tool to accomplish more complete, complex and sophisticated analysis.