Browsing by Subject "Maintenance Policies"

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    Maintenance and marginal cost analysis of a two-unit cold standby system
    (1997) Hamdaoui, Chokri
    The Marginal Cost Analysis (MCA) of maintenance policies is a concept gaining interest in the recent years. This approach, due to Berg, has been categorized as an Economics Oriented Approach, as different from the classical probability centered approach. The MCA has been successfully applied to the Age Replacement and the Block Replacement policies, and was shown to be flexible enough to permit extensions and generalizations. In this thesis, we apply the MCA approach to a more complex model. We consider a two-unit cold standby system. Upon failure of the working unit in the time interval [0,T) the unit is replaced by the standby unit if available. If the standby unit is in repair, the system is down, and a downtime cost is incurred. The item inspected at time T is in one of two states: “good” , or “critical” . The good unit continues operation, whereas a unit in critical state is sent to repair. The switchover is immediate. We derive and compare the marginal cost function as well as the long-run cost per unit time function.
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    A policy for the maintenance of a multistate multicomponent series system
    (1997) Kaya, Alev
    In real life situations various levels of performance for both systems and components are identified. Deterioration of systems and components has been considered by many maintenance and replacement models in the literature, but most of these models are for single component. Our study concerns a multistate multicomponent maintenance model. We extended the model studied by Van der Duyn Schouten and Vanneste (1993) with four states, (0,1,2,3), to a multistate system with 5 + 1 states, (0, 1,..., S). While classifying these S +1 states, we use two different classification schemes corresponding to different real life situations. Then, we analyze our model under both exponential and Erlang sojourn time distributions for both state classification schemes. As a result of our analysis, we derive expressions for the long-run average cost per unit time. We used the randomization method to evaluate the transient state probabilities during the implementation of the average cost expressions.