考虑等待时间约束的不完美生产系统的产出优化

针对某些生产系统存在等待时间约束及设备劣化引起产品质量损失这2个问题,构建了系统的缓冲区控制和预防性维护的联合优化模型。首先,利用伽马过程对下游瓶颈工作站的劣化过程进行建模,并考虑由于其状态劣化引起的产品质量损失;其次,在此基础上,将工件的到达、中间缓冲区及下游工作站的加工过程视为一排队系统,引入M/G/1/K排队模型分别求解了在制品(WIP)被阻塞和超出等待时间约束的概率;最后,以最大化系统的"有效产出"为目标,对系统的预防性维护和缓冲区控制作了联合优化。数值实例表明:本文所提模型是切实、有效的,对带等待时间约束的生产系统的缓冲区控制、预防性维护以及产出提高具有一定的指导意义。

Throughput optimization for an imperfect production system with queue time constraints

To efficiently solve the problems of queue time constraints and quality loss caused by machine degradation during production activities,a joint optimization mathematical model considering both preventive maintenance and the control of the buffer capacity was constructed in this paper.First,gamma process was introduced to model the degradation of the downstream bottleneck station,and the quality loss caused by its degradation was also considered.Second,based on the model mentioned above,we treated the arrival of workpieces,the intermediate buffer and the working process of downstream station as a queuing system and obtained the probability of work in process (WIP) blocking and exceeding the queue time constraints using M/G/1/K queuing model.Finally,with the objective function of maximizing the "effective throughput",we jointly explored the optimization of the threshold of preventive maintenance and the capacity of the intermediate buffer.Numerical example shows that the proposed model is practical and effective,which has certain instructive significance to the buffer capacity control,preventive maintenance and throughput improvement for those imperfect production systems with queue time constraints.