Study on the dynamic characteristics of spare inventory based on Markov process

The dynamic characteristics of spare inventory under nonstationary demand were researched. The Markova state transition equation of spare consume distribution function was formulated and the function derivations of expectation and variance of consumed spares with respect to time were obtained. On the base of above mentioned analysis result, the methods of calculating the expectation, variance and distribution function of consumed spares were given at arbitrary time point. Curves of the expected consumed spares (E(t)) and the expected back orders (EBO(t)) vs. time were plotted by numerical integral, influences of the demand rate and the turnaround time rate of the spares on E(t), EBO(t) were analyzed.