Simple Analytical Models for Perishable Inventory Systems.

Abstract : This paper develops three distinct models for studying perishable inventory systems. The perishable items have a deterministic usable life after which they must be outdated. For each of the models, analytical expressions are found for steady-state distributions which characterize the inventory systems. Knowledge of this steady-state behavior may be used for evaluation of system performance, and for consideration of alternatives for improving system performance. The first model considered assumes that both the demand process and the inventory replenishment process are stochastic processes that may be modelled as Poisson processes. The second and third model assume that inventory is replenished by a constant production process. The second model, assuming continuous inventory units, has Poisson demand requests with the size of each request distributed as an exponential random variable. The third model has Poisson demand requests with all demands being for a single unit. (Author)