The evaluation of the interaction between dispatching rules and truncation procedures in job-shop scheduling

Previous research has suggested the use of truncation to alleviate problems of high variance in flow time and tardiness when dispatching jobs using the shortest processing time rule. These studies have suggested truncation schemes based on the time a job spends waiting in the queue to be processed, and on job slack. This study describes three new truncation procedures, along with the two existing methods, that truncate jobs based on their critical ratio, operation slack, and change in queue rank. In addition, the truncated (priority) jobs are dispatched using four common dispatching rules. The results show that the interaction between truncation schemes and dispatching rules is always significant, and that the new truncation schemes proposed here perform as well as or better than older methods with respect to certain performance measures.