ABSTRACT
To start our discussion, let us consider anew the particular system (Case 2(a)) treated in Sections 5.1 and 5.2. This system consists of two identical units, each assumed to be active and possessing a common time to failure p.d.f. f(t) = λ exp{−λt}, t ≥ 0. It is further assumed that there is a single repairman and that the time to repair a failed unit is exponentially distributed with p.d.f. g(t) = µe−µt, t ≥ 0. Failure of a unit is assumed to be instantaneously detectable and repair is immediately initiated, if the repairman is free. We let Ej denote the state in which j units are good. In Section 5.2, we found formulae for Pij(t), the probability that the system is in Ej at time t given that it was in Ei at time zero and in Section 5.1 we gave formulae for pj = limt→∞ Pij(t), the long-run probability of being in state Ej .
