Research for Inventories

This paper demonstrates how to determine the minimal cost combination of end products and investment in repair service capability in order to maintain a given level of operating end products. The model is then applied to the problem of determining the optimal size of the Navy's F-4 aircraft pipeline.

This paper is concerned with calculating the significant measures of supply effectiveness for activities which involve the resupply of reparable items (spares). The approach that is taken is to derive an expression for the number of unsatisfied demands existing for the items at a point in time. This expression can then be employed to calculate the desired measures of supply effectiveness which describe the behavior of the model. Several numerical examples illustrating the model's use are presented in the concluding part of the paper.

A serious criticism of the inventory models presented in the literature is that they often seek to minimize inventory costs rather than to minimize total costs for a specified production level. This neglect is caused, in large measure, by a failure to consider inventories as factors of production, with substitution possibilities between other types of inputs. This paper incorporates these substitution possibilities into the analysis, and formulates an inventory model within the theory of the firm.

The Officer Projection Model (OPM) projects the flow of officers through the ranks of the U.S. Navy. It projects an initial officer inventory (characterized by length of service, grade, and promotion status) in yearly increments, accounting for attrition, promotion, legal constraints (Title 10 of the U.S. Code), and such management policies as minimum accession requirements and end strength targets. It is devoted especially to simulating the Navy's officer promotion system, and provides several options which consider the interactions of flow point, promotion rate, zone size, grade structure and end strength, and early and late selection. The OPM will also compute annual compensation, separation pay, retirement pay, and the present value of retirement pay for the remaining life expectancy of projected retirees. The model provides management with a tool for evaluating alternative promotion policies and retirement proposals, and for studying the interactions of officer end strengths, promotions, and accessions, and the cost of changes in longevity and grade structure. The Guide for Users, Volume I, describes the Navy's officer system and the model and discusses the data and policy variables to be specified by the user. The Guide for Programmers, Volume II, provides a detailed explanation of the computer coding as an aid to changing, and making special adaptations of the model.