چکیده:
In this paper, the flexible job shop scheduling problem with machine flexibility and controllable process times is studied. The main idea is that the processing times of operations may be controlled by consumptions of additional resources. The purpose of this study is to find the best trade-off between processing cost and delay cost in order to minimize the total costs. The proposed model, flexible job shop scheduling with controllable processing times (FJCPT), is formulated as an integer non-linear programming (INLP) model and then it is converted into an integer linear programming (ILP) model. Due to NP-hardness of FJCPT, conventional analytic optimization methods are not efficient. Hence, in order to solve the problem, a Scatter Search (SS), as an efficient metaheuristic method, is developed. To show the effectiveness of the proposed method, numerical experiments are conducted. The efficiency of the proposed algorithm is compared with that of a genetic algorithm (GA) available in the literature for solving FJSP problem. The results showed that the proposed SS provide better solutions than the existing GA.
خلاصه ماشینی:
"Keywords: Flexible Job Shop Scheduling; Controllable Processing Time; Scatter Search; Disjunctive Graph.
In recent years, several meta-heuristic methods have been used for solving the flexible job shop problem, such as genetic algorithms (Zhang, et al, 2011), tabu search (Li, et al.
This study is an attempt to solve the problem of flexible job shop with controllable processing times using a scatter search algorithm.
In this study, job shop scheduling problem is developed by adding controllable time and given the complexity of flexible job shop problem, the meta-heuristic algorithm for scatter search was used to solve the mathematical model.
With regard to the structure of the problem, the problem can be defined in three sub-problems: Sub problem of sequence of operations Sub problem of allocation Sub problem of process mode So the representation form of solutions should be so that shows all three sub problems, in this study, the following method is used for each sub-problem, a layer is designed and the number of elements of each layer equals to all operations of the job.
Therefore, companies seek to reduce costs by adopting the proposed approach, as suggested in this study, which introduces by controllable times and meta-heuristic scatter search algorithm for obtaining efficient solutions are presented.
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