A note on ordering policies with cost of observation and lead times

This paper deals with the optimum ordering policy for a one-unit system, where each failed unit is scrapped without repair and each spare is provided after a constant lead time by an order. The optimum ordering policy minimizing the expected cost per unit time in the steady state is discussed by introducing the two types of lead times and observation cost along with ordering costs and downtime cost. Under certain conditions, a finite and unique optimum ordering time is obtained. A special case for the age replacement model is deduced from this model.