Narrow Results

In this paper, it is aimed to propose a notion of the alternating renewal process to mathematically model a multi-failure complex system in order to develop its availability and maintenance measures. In the study, M/E₂/1 queueing model with infinite waiting space during service times of components has been worked out under the FCFS discipline. Inspections are performed at regular intervals to detect breakdowns. The primary objective of the paper is about obtaining the system’s reliability, availability, and the optimal interval period with minimum maintenance cost. To validate the mentioned model a case study has been done on the Power Distribution System. Finally, a comparative study between M/E₂/1 and M/M/1 queuing models is done and the various aspects based on availability and long-run cost are focused in the analytical result. The results were direct toward enhancing the availability of the system and making the decision about an appropriate inspection period.

The opportunistic maintenance of a k-out-of-n:G system is studied in this paper. In many applications, it spends less cost and time to perform maintenance on several components jointly than on each component separately. Based on this fact, two new (τ, T) opportunistic maintenance models with the consideration of reliability requirements are proposed. In these two models with two decision variables τ ≤ T, only minimal repairs are performed on failed components before time τ, and corrective maintenance of all failed components are combined with preventive maintenance (pm) of all functioning but deteriorated components after τ; if the system survives to time T without perfect maintenance, it will be subject to pm at time T. Considering maintenance time, asymptotic system cost rate and availability are derived. The results obtained generalize and unify some previous research in this area. Application to aircraft engine maintenance is presented.