An investigation of reliability optimization in standby systems

Due to the limitations of space or extra costs incurred, the reliability optimization problem of a spare system is of great interest and importance. In this article, we devote our efforts into the investigation of reliability optimization problem of the warm spare gate and cold spare gate. For a spare gate with fixed components, we first examine the relationship between the component order and the corresponding reliability; then, the equivalence of a cascaded model with a multiple-input spare gate is further presented. We find that for a warm spare gate, the corresponding reliability value is anticipated to be affected by the adopted component replacing order; nevertheless, the reliability is a fixed value once the components are provided for a cold spare gate. This finding indicates that reliability is irrespective of the component order for a cold spare gate. Therefore, for the warm spare gate, the component order can be varied to improve the corresponding system reliability, whereas for the cold spare gate, we should attempt to improve the reliabilities of the spare components aiming to obtain a higher reliability. These findings are potentially useful in the design process of a system consisting of spare gates.