A Novel Perspective on Reliable System Design With Erlang Failures and Realistic Constraints for Incomplete Switching Mechanisms

This study focuses on effectively designing reliable systems. Such systems are capable of withstanding failure events by applying multiple realistic workarounds. These workarounds include allocating redundancy, component reliability, and backup strategy that are considered concurrently as decision variables. In this novel view, the strategy and reliability of components are determined freely and independently to achieve optimality. The research problem is implemented in a general case to audit the capabilities of the proposed approach in realistic situations. This case deploys an Erlang time-to-failure probability density function together with incomplete switching. With its improved reliability and resource functions, the proposed model challenges the existing presumption regarding the superiority of the cold-standby approach in the mentioned field and provides a realistic trade-off between different redundancy strategies. This practical view reflects on reliability, cost, weight, and volume of the switch, simultaneously. The findings revealed that the proposed joint reliability-redundancy allocation problem, with an added freedom of strategy choice, outperforms the pure cold-standby counterpart. Owing to the NP-hard nature of the problem, a simplified particle swarm optimization algorithm is suggested and utilized as a solution method. The performance of the novel view is assessed using multiple benchmark instances including some typical problems from the literature. Our numerical analysis demonstrates the superiority of this approach with our maximum possible index reaching up to %96 compared to the existing results in the past works. Furthermore, the selected solution algorithm is compared with a differential evolution algorithm. We show that this simplified particle swarm optimization algorithm performs considerably better in all tested scenarios.