Abstract
In these days, a lot of productive activities are divided into small processes and coordinated under several collaborations. Therefore, we need to deal with large and complex scheduling problems. In this paper, we introduce a model in which several RCPSPs form a whole scheduling problem represented by a directed graph based on a precedence relation. Moreover, resource prices are getting higher recently and we must utilize resources more and more efficiently. In order to consider more efficient utilization of resources, we allow resources to be transferred from some RCPSPs to other RCPSPs under appropriate constraints in our model.
This paper addresses this problem of multiple projects with two types of objectives, minimizing the project completion time and minimizing the sum of weighted earliness-tardiness costs of each RCPSPs. For these objectives, we propose some methods to construct a schedule which has more efficient resource allocation. Our proposed methods have three phases. In the first phase we compute each RCPSPs' completion time, in the second phase we construct whole project schedule optimized for project completion time or total weighted earliness-tardiness costs and in the third phase we determine resource transfer schemes. We find out bottle neck RCPSPs of the schedule for each objective and improve their completion time by transferring resoureces to them from other RCPSPs in the third phase. We iterate these three phases for a certain number of cycles and obtain a better schedule. We also confirm efficiency of our proposed methods through computational experiments.
