Ali Karevan; Mohammadreza Vasili
Abstract
Maintenance costs are one of the major costs in plants and companies. The observation in many cases illustrates the lack of plans or mistakes in maintenance activities that incurred great costs. In this study, the number of equipment failures have been determined. Then the failure rate and reliability ...
Read More
Maintenance costs are one of the major costs in plants and companies. The observation in many cases illustrates the lack of plans or mistakes in maintenance activities that incurred great costs. In this study, the number of equipment failures have been determined. Then the failure rate and reliability of each equipment are calculated. The third step calculates total system reliability so the initial plan is presented. After that, by using the obtained information, the sustainability aspects of the program will generate and the maintenance costs and sustainability functions will assess. At the end, this multi-objective optimization problem is solved by MOPSO algorithm and the results are compared with a simulation method. As a result, with this reliability centered maintenance program, the reliability of each equipment, as well as the whole system are improved; economic aspect of sustainability and customer satisfaction are increased; environmental pollutions and maintenance costs are decreased by offering more reliability based program; a scheduling plan for each maintenance procedures is provided and also more stable internet connection is established by reducing the system failures.
Seyed Mahdi Homayouni; Ali Izadi; Mohammadreza Vasili
Volume 1, Issue 3 , September 2014, , Pages 148-158
Abstract
Many researches in inventory control area of knowledge have been focused on single objective and multi-objective problem of determining the economic quantity of order. In single objective problems, costs were considered as the objective. However, multi-objective problems have not been well investigated. ...
Read More
Many researches in inventory control area of knowledge have been focused on single objective and multi-objective problem of determining the economic quantity of order. In single objective problems, costs were considered as the objective. However, multi-objective problems have not been well investigated. For instance, there are no hint to transportation cost, budget, or holding costs, or only capacity and demand constraints have been considered in these researches. This study focuses on developing a model accompanied by costs, quality and the time of delivery.The economic order quantity of multi-product from multi-supplier in multi-period under uncertainty in demand and discounted prices are considered in this paper. In first step, a mathematical model is developed for this problem. This mathematical model is solved by using multi-objective optimization method i.e. goal programming. Then, a meta-heuristic method based on multi-objective particle swarm optimization is proposed. Results of the small size numerical examples show that solutions found by using the proposed meta-heuristic method are in average, 5% worse than solutions found by using the mathematical methods; however, it needs much lower computational time.