Research On Cross-Enterprise Project Scheduling Optimization Methods

The cross-enterprise project is a complicated systems engineering. It is under the constraints of all kinds of resources and working procedure logical relationship during implementation, and simultaneously has many uncertain elements of uncertainties, which means certain robustness of project scheduling will be required. But the movement of production system is actually difficult to keep in an invariable project scheduling, so it is hard to avoid the on-line adjusting, which makes scheduling problem be a dynamic process with continuous optimization. In order to ensure the project to be finished on time, the scheduling plan must be reasonable and feasible.This dissertation pointes out the important meaning of the critical chain technology to the science research and projects based on the background of problem studied; the basic principles, features and problems of the proactive and reactive strategy are summarized. Cross-enterprise project scheduling optimizations based on the proactive and reactive strategy are researched thoroughly and deeply. The algorithms are put forward in this dissertation for the problems of project scheduling robustness.Firstly, this dissertation introduces the technology of critical chain which is based on the theory of constraints, and adopts the heuristic algorithm which is based on the regulation of the latest start time with high priority to obtain the near-optimal scheduling algorithm. Buffer of the link is established in each working process respectively under the overall consideration of tensity of resources and complexity of project. So critical chain and the non-critical chain obtain the moderate buffer sizes, and the finish rate of the entire project is ensured. The priority of resources is obtained by using the gray connection analysis to compute the conflict working procedure, which enables the resources configured reasonably.Secondly, buffer size is able to be added to each chain separately. The working processes are examined from end to front to confirm whether the tight relations and the resources conflict have or according to"a later operation is better"principle with the latest start time as criterion. The start time of working process is adjusted on this basis so as to obtain the final project scheduling chart. Simultaneously the mathematical model is bulit with the level of product and the lowest net cost as the goal, which proves the robustness of the strategy.Finally, a new robust scheduling strategy is proposed based on the proactive strategy and reactive strategy. In view of the problem that the processing time of working processes is uncertain, the realized strategy shows: the proactive scheduling strategy with the highest goal expected value is obtained by the optimization scheduling model which contains the indefinite process time parameter. And then the start time of successor process task is determined by the corresponding restraints in the model and the actual information reflected from product. By analogy the online adjustment is realized. The simulation confirmation showes that this strategy guarantees the robustness of the entire scheduling, enhances the reaction rate of the online adjustment, and then achieves the synthesis optimization of the project.The implementation of system functionality verifies the validity of the algorithms.