یک رویکرد PSO برای مدل تعمیر و نگهداری یکپارچه
Abstract
1- Introduction
2- Literature review
3- An integrated maintenance model
4- An improved PSO
5- Computational experiments
6- Conclusions
References
Abstract
To decrease the over-maintenance and under-maintenance phenomenon, this paper examined the relationship between facility reliability and lifespan so as to generate the optimal maintenance plan which includes the proper combination of maintenance time and maintenance modes. An age reduction maintenance model is built to describe the deterioration situation of the port facility, and a particle swarm optimization (PSO) based integrated approach is used to solve the model. The sensitivity analysis helps to determine the maintenance mode combination from which the total maintenance cost is minimized. The result shows that taking multiple maintenance modes into account would help optimize the total maintenance cost. In addition, the obvious difference between the reliability thresholds would assist in providing discrepant maintenance service. The results have indicated that when the thresholds of different maintenance mode are overlapped, the total maintenance cost is the highest.
Introduction
In recent years, the port economy gains a prosperous development, and the life cycle of port devices are designed to be longer, making facility management a critical part among the port management stream. The environmental and economic concerns become high, among which, the facility maintenance plays an important role. Most of the port facilities are exposed to a mixed environment of the windy, sunny, salty and high load operation. Any facility is a necessary link in the port operation chain, and the interruption of any link will cause a great damage to the port operation efficiency. Every year, about 11% of operating cost is used for maintenance, and this number has been increasing at an annual rate of 4% in recent years with the increase of port throughput [7]. Furthermore, according to the report on China port development [2], around twelve percent of the port machine OEM's revenue is coming from the maintenance activities, where the maintenance costs for crane are growing at double-digit rate annually [13]. To deal with these growing cost, an appropriate facility maintenance scheduling becomes essential both for port operators and port machine manufacturers. Normal overcapacity often characterizes port operation due to the high facility cost. This causes port facilities are always operated either far beyond or below their full capacity subjected to the resilient loading plan. Such overcapacity or under-capacity usually results from various facility type and fluctuating workload. The variable facility type results in the wear and tear at varying degrees even when they are assigned the same workload. The workload fluctuation, either due to field dynamics or demand dynamics, leads to strong fluctuation in tear mix and deterioration extent. Different types of facilities support smooth port operation, while outdoor environments intensifies serious wear and tear on the facility. A common practice is, therefore, to apply maintenance whenever possible to postpone or avoid excessive wear and tear [8]. Since maintenance recovers the reliability in some measures, their consideration has attracted increased attention with highlighted focus on reasonable maintenance mode. Various maintenance modes influence aging rates and thus impacts the next maintenance activities, such as maintenance interval, technique, and cost.