Availability of markov repairable systems with changeable operating regimes

More than one operating regimes are involved in a Markov repairable system with changeable operating regimes. The system can adjust its operating regimes to adapt to diverse exterior environments. Assume that the transition rate matrices under distinct operating regimes are different and the sojourn times in distinct regimes are governed by a finite state Markov chain. The availability of the system is studied using the matrix method, the Laplace transform and theory of Markov process. A numerical example is given to illustrate the results in the paper.