María Dolores Berrade

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The maintenance of a single unit system that alternates operating and idle periods is studied. In the former case the failures are detected as soon as they occur and only by special testing or inspection in the latter. This paper aims at minimizing the cost per unit of time for an infinite time span by selection of a unique interval, for both inspection and(More)
We carried out a study of the aging characteristics in two mixing models having additive and proportional hazards, respectively. The relation between aging properties of such mixtures and that of an exponential mixture is described. The effect of mixing on the properties of the stochastic aging as well as the relation between the mixture and the(More)
This paper deals with the maintenance policy of a system subject to periodical inspections aimed at detecting the occurrence of failures. After the first N−1 failure, the system undergoes an imperfect repair that brings the system back to the operating condition while the Nth failure is followed by a perfect repair restoring the unit to an as-good-as-new(More)
This paper models imperfect inspection policies for a system with a finite operational time requirement. Two types of maintenance policy are considered: that in which an alarm (a positive inspection) is followed by a check of the validity of the alarm at additional cost, and if the system is good it continues in service and if failed it is retired; and that(More)
It is quite plausible that any device or system reliability shows an increasing failure rate (IFR) as age, use or both may cause it to wear out over time. Nevertheless, explaining a decreasing failure rate, which means an improvement as time goes by, is far from intuitive. Mixtures of lifetime distributions turn out to be the most widespread explanation for(More)
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