Order acceptance and scheduling in a job shop environment ; two type of order: Emergency and Regular orders

Order acceptance and scheduling, as two critical decisions, can be studied separately or simultaneously. In this paper, we investigate the order acceptance and scheduling concurrently in the job shop environment. We consider two types of orders; emergency order and regular order. An emergency order should be produced while for a regular order, we should decide about accepting or rejecting it. The objective function is to maximize the profits that can be obtained from accepting the regular order by considering the tardiness penalty for both types of orders. In addition, all orders have fixed due dates, processing times, and processing routes in a job shop environment with recirculation. For solving the problem, we propose two genetic algorithms, the first of which has two different chromosomes: a binary chromosome that produces all states of accepting or rejecting the regular order and a chromosome that contains the operations of accepted regular and emergency orders. The second algorithm is a hybrid heuristic-GA algorithm. In order to evaluate the performance of the algorithms, some problem instances are generated using standard methods. The results show that the first algorithm has a high performance in small and medium size instances while the second algorithm outperforms the first one in large size instances.

Keywords:

order acceptance , scheduling , job shop , recirculation , genetic algorithm