A Two-Stage Optimization Method with Multiple Objectives for the Emergency Maintenance Process

A timely emergency maintenance operation can prevent the failure problem from getting worse. And it can eliminate potential safety hazards and ensure the safety of operators and the equipment. A two-stage optimization method with multiple objectives for the emergency maintenance process is proposed. Firstly, a Graphical Evaluation and Review Technique (GERT) model is established to describe and evaluate the emergency maintenance process. Expected expressions of maintenance time and maintenance effectiveness are derived based on the GERT model, which are set as multi-objective optimization functions. The tradeoff between the optimal maintenance time and maintenance effectiveness is realized by the multi-objective particle swarm optimization (MOPSO) algorithm. Based on the obtained Pareto optimal solution sets through MOPSO algorithm, the maintenance time and maintenance effectiveness are re-optimized with the goal of the minimum system performance loss to determine exact optimization results. The proposed method is demonstrated by taking the emergency maintenance process optimization of the subsea tree as a case.