Markovian multiechelon repairable inventory system

In this article the authors model a two-echelon (two levels of repair, one level of supply) repairable-item inventory system using continuous-time Markov processes. They analyze two models. In the first model the authors assume a system with a single base. In the second model they expand this model to include n bases. The Markov approach gives rise to multidimensional state spaces that are large even for relatively small problems. Because of this, the authors utilize aggregate/disaggregate techniques to develop a solution algorithm for finding the steady-state distribution. This algorithm is exact for the single-base model and is an approximation for the n-base model, in which case it is found to be very accurate and computationally very efficient.