Random number of units for K-out-of-n systems.

This paper takes up the reliability and preventive replacement problems for a K -out-of- n system, where K is a stochastic parameter provided. Firstly, we consider the case when K is predefined as constant numbers as is done with the traditional method, and obtain the system reliability R ( t ), mean time to failure (MTTF), and replacement policies, in which the number n of units for replacement and replacement time T of operation are, respectively, optimized. Secondly, we focus on the above discussions again when K cannot be predefined constantly, but it is a random variable with an estimated probability function. Furthermore, we give approximate computations in an easier way for MTTF, optimal number n * and replacement time T *, respectively. [ABSTRACT FROM AUTHOR]