关键词: 受限资源, 多项目调度, Petri网, 仿真

Abstract: Uncertain project duration method couldn't describe state changes in sequence accurately and explicitly, there was only approximate solution. In order to deal with this problem, a modeling method by extending Petri net was proposed. Scheduling problems in resource-constrained projects with definite duration and changeable duration were modeled. This method classified tokens into logic token and resource token, and token's transformation represented the task execution as well as resource allocation respectively. Through classifying place, transitions and timed place, the places were divided into activity place, resource place, waiting place, and final place, and transitions were divided into coordination transition, resource scheduling transition and resource releasing transition. Through coordination transition, the timing relationship among tasks were reflected in waiting place and activity place; through resource place, resource scheduling transition and resource releasing transition, the competition, occupation and release of tasks for resources were reflected. By adding places and transition types and modifying transition firing rules, the actual system of uncertain duration was described. Through examples in PSPLIB library, the model solution success rate, model solution fitness and comparative test for extended Petri net were analyzed. The effectiveness of proposed model was verified by an actual engineering application.

Key words: resource constrained, multi-project scheduling, Petri nets, simulation