مسئلۀ زمان‌بندی و تخصیص جریان کارگاهی در اورهال تجهیزات

در این مقاله، یک مسئلۀ زمان‌بندی جریان کارگاهی به‌منظور اورهال تجهیزات ارائه شده است. این مسئله شامل سه مرحله است که در مرحلۀ اول، عملیات تفکیک اجزای یک تجهیز و در مرحلۀ دوم، عملیات تعمیرات و اورهال بر قطعات تفکیک‎‍شدۀ مرحلۀ اول انجام می‌شود؛ سپس در مرحلۀ سوم، قطعات اورهال‎‍شدۀ مرحلۀ قبل بر هم سوار می‎‍شوند. در مرحلۀ سوم، کارگاه‎‍های موازی، عملیات را به‌صورت موازی انجام می‌دهند. تابع هدف مسئله، بیشینۀ زمان تکمیل کارهاست و توالی پردازش کارها باید به‌‌نحوی باشد که مقدار تابع هدف، کمینه شود. به‌منظور حل مسئله، یک مدل برنامه‎‍ریزی عدد صحیح آمیخته برای سایز کوچک ارائه شده است که براساس موقعیت هر کار، توالی پردازش کارها را مشخص می‎‍کند. برای حل مسئله در ابعاد بزرگ، الگوریتم ژنتیک به کار رفته است. با افزایش سایز مسئله و در سایزهای مختلف، نتایج بررسی و تجزیه و تحلیل شده است که این کارایی مدل و الگوریتم ارائه‎‍شده را نشان می‌دهد.

flow shop scheduling and assignment problem in equipment overhaul

purpose: this paper aims to propose a flow shop scheduling problem for equipment overhaul. this problem consists of three stages, the separation of the components of an equipment is done in the first stage. repairs and overhaul operations are carried out on the separated parts of the first stage in the second stage. finally, the overhauled parts of the previous stage are mounted on each other in the third stage. in the third stage, operations are performed in parallel workshops. the objective function of the problem is the maximum time to complete jobs, and the sequence of processing jobs should be done in such a way that the value of the objective function is inimized.design/methodology/approach: to solve the problem, a mixed integer programming model has been proposed for small size, which determines the processing sequence of jobs based on the position of each job. a genetic algorithm has been used to solve the problem in large dimensions. by increasing the size of the problem and in different sizes, the results have been examined and analyzed, which shows the efficiency of the model and the proposed algorithm.findings: to check the accuracy of the model’s performance and also the effect of the presence of parallel machines in the third stage, an example was presented in this paper. accordingly, while the accuracy of the model’s performance was checked, the effect of the presence of more machines was determined in the third stage. as the number of machines increased in the third stage, the value of the objective function did not deteriorate. the performance of gams in solving the problem in a small size was investigated. considering that solving the problem for large dimensions is not possible in a reasonable time and the problem is np-hard, then solving the problem in large dimensions was done using a genetic algorithm. therefore, solving the problem on a large dimension has been done using the genetic algorithm. according to the obtained results, the efficiency of the genetic algorithm was shown. due to its low average value, it indicated the convergence of the genetic algorithm.research limitations/implications: considering that there are not many published papers in the field of equipment overhaul, it is difficult to access related models and papers. therefore, in this paper, the model and solution method have been written with many reviews. also, to check and reduce costs, the number of third-stage machines has been determined using sensitivity analysis.practical implications: the problem of equipment overhaul is used in many fields in reality. for example, the operations related to the maintenance, repair and overhaul of the aircraft engine have been investigated. since the planning of maintenance and maintenance operations is difficult, the focus of research has been on improving maintenance operations by finding suitable scheduling for job shop operations in maintenance operations. they emphasized that scheduling can improve maintenance operations and presented a simulation model.social implications: the purpose of creating a space to start an activity is to reduce costs, earn money and achieve profit. to examine the cost-effectiveness of the equipment overhaul issue, we can refer to the number of third-stage machines. according to the amount of equipment to perform an overhaul on them, the number of third-stage machines can be determined.