Some approximate inspection policies for a system with imperfect inspections

Consider a system with an exponential lifetime distribution in which the bad working state is only known if it is inspected. Suppose that each inspection and each unit time of system bad working have fixed costs. If the inspections are not error-free, it was proved that the optimal inspection policy is not a periodic one. The paper presents for this model some approximate periodic inspection policies, with numerical results, proving that they are very good in practice. Particularly, it presents and analyses two simple solutions for the inspection period which are generalizations of previous approximations.