Research for Inventories

This research memorandum presents a means of calculating the expected length of 'awaiting-parts time' of weapon replaceable assemblies, which are needed to calculate aircraft readiness in a multi-indenture, readiness-based sparing model. The method presented is appropriate for any other level of indenture. Although full scale application of the model is not feasible at this time, the model aids in comparing and evaluating existing models.

Two inventory models are compared in this paper. The first model solves for the optimal purchase of all inventory items simultaneously. The second model solves for the optimal purchase of each inventory item considered one at a time, using a penalty parameter that is chosen to satisfy an availability goal. It is shown that the solutions of the two models are not equivalent. Moreover, the second model is too sensitive to changes in the relative demand rate but not sensitive enough to changes in relative holding costs. Supersedes 05 850765.10

A base of inventory and utilization data for computers, aircraft, and radars was developed through a survey and the future availability of the capital services from these assets was projected. In addition to the services from federally-operated assets, the projections include those from other sources such as universities and contractor-operated laboratories. The utilization data include both actual and potential full use of each asset, and these data are used to address the extent of possible underutilization of the assets. The projected services are compared with the reported requirements of agency-approved atmospheric research programs to provide an initial estimate of the adequacy of the planned capital inventory.

The Aircraft Force Projection Model (AFPM) is designed to project the Navy's aircraft inventory over a ten-year period and attempts to satisfy the operating requirements of a given set of forces with the projected operating inventory. In addition the AFPM generates useful characteristics of the aircraft inventory such as projections of the age distributions, attrition quantities, pipeline requirements, and rework requirements. This volume describes the input data file, file maintenance procedures, and how to run the model. The Aircraft Force Projection Model (AFPM) is documented in two volumes. Volume I, The Users Guide, describes the input data file, file maintenance procedures, and how to run the model. Volume II, The Programmers Guide, contains a detailed explanation of the AFPM computer programs and program listings.