Effects of processing time fluctuate on scheduling rule

In discrete manufacturing system the time to processing work-piece are often uncertain. It is important to study the processing time fluctuate and its effect on scheduling for us to improve the production plan, and control. We have analyzed the distributed relationship of processing times between two jobs and have developed a model for the failure probability of scheduling rule in the case that the distributed extents of processing times of two jobs overlap. We have further developed a model of failure probability for the case of multi-jobs, and have analyzed the impacts of the processing time expectation difference of the jobs and of the fluctuate extent of processing time on the failure probability of the scheduling rule.