Multi‐Objective Optimization and Engineering Management

Abstract

The subject discussed in the paper is the multi‐objective optimization of industrial management which is one of the topics of the journal. Indeed, as the economic competition turns harder and harder, industrial companies have to face much more difficulties. To afford that problem, they have to optimize different criteria simultaneously. In addition to that, today’s customers want the right product at the right price and at the right time. That is why multi‐ objective optimization becomes more and more a main issue in the management of production systems. The rest of this short document aims to underline the main techniques and resolution methods used in the multi‐objective optimization and especially to solve multi‐objective scheduling and lines design problems. As a starting point, we have to claim that the different objectives must be contradictory. Otherwise, the problem can be easily solved with the scalar multi‐objective optimization. Since scheduling problems are first discussed here, specific objectives usually studied are described. In scheduling problems; the most studied criterion is the makespan minimization which increases the production rate of the system. Another objective is the minimization of the total tardiness of the tasks which increases the service quality and customers’ satisfaction. Another objective is the variability of the cycle time which decreases sudden changes in the workload. Thus, dealing with multi‐objective optimization is essential if one wants to increase the production rate without decreasing the quality of service. The multi‐objective optimization is therefore with a challenge to tackle and encounter the tradeoff between several criteria or objectives. For the multi‐objective lines design problems such as buffers sizing, line balancing or equipment selection s, different objectives may be taken in consideration. Two criteria are generally the most studied ones: the minimization of the cost of the line and the maximization of the line throughout rate. The cost minimization allows lines manufacturers to be more competitive in the market. Besides, the line throughput rate maximization allows enhancing the service level for example. However, throughput rate maximization means automatically being constraint to use efficient machines which are naturally more expensive than less efficient machines. A trade‐off must be found to maximize the technical objective (throughput rate) and to minimize the financial objective (the cost of the line).