Abstract
•1-out-of-N standby system is considered.•Elements can be in two standby modes with different activation readiness.•The standby mode transfers occur in predetermined time.•Each element has limited resource and is inactivated upon resource depletion.•An algorithm for evaluating mission downtime is suggested.•Optimal mode transfer schedule is found.
It has been shown that mode transfers can effectively balance the resource consumption and restoration time of standby systems. However, the existing methods assumed unlimited resource in each element, which is not practical for many real-world systems. This work advances the state of the art by considering resource-constrained system elements, which have some maximum lifetime due to resource depletion during the mission. The optimal element standby mode transfer problem is formulated and solved, which determines the mode transfer schedule minimizing the expected mission downtime (EMD). The solution methodology encompasses a new event transition-based numerical algorithm for evaluating the EMD of the considered 1-out-of-N standby system subject to mode transfers. Through the detailed analysis of a sensor standby system, it is revealed that the EMD decreases and the scheduled warm to hot mode transfer time increases as the element's initial available resource increases; the EMD increases as the element's resource consumption or stress level during the mode transfer increases; the EMD and its fraction in the mission time increases as the mission time increases; and it is beneficial to put the element with the smallest initial available resource into operation first.