EXTENDED BLOCK REPLACEMENT POLICY OF A SYSTEM SUBJECT TO SHOCKS

A generalization of the block replacement (BR) policy is proposed & an alyzed for a system subject to shocks, Under such a policy, an operati ng system is preventively replaced by new ones at times i . T (i = 1,2 ,3,...) independently of its failure history, If the system fails in: ((i-1) . T, (i-1) . T + T-0), it is either replaced by a new one or mi nimally repaired, [(i-1) . T + T-0, i . T), it is either minimally rep aired or remains inactive until the next planned replacement. The choi ce of these two actions is based on some mechanism (modeled as random) which depends on the number of shocks since the latest replacement, T he average cost rate is obtained using the results of renewal reward t heory, The model with two variables is transformed into a model with o ne variable and the optimum policy is discussed, Various special cases are considered. The results extend many of the well-known results for BR policies.