title: Project scheduling under time dependent costs-a branch and bound algorithm
abstract: In a given project network, execution of each activity in normal duration requires utilization of certain resources. If faster execution of an activity is desired then additional resources at extra cost would be required. Given a project network, the cost structure for each activity and a planning horizon, the project compression problem is concerned with the determination of optimal schedule of performing each activity while satisfying given restrictions and minimizing the total cost of project execution. The paper considers the project compression problem with time dependent cost structure for each activity. The planning horizon is divided into several regular time intervals over which the cost structure of an activity may vary. But the cost structure of the activities remains the same within a time interval. The objective is to find an optimal project schedule minimizing the total project cost. We present a mathematical model for this problem, develop some heuristics and an exact branch and bound algorithm. Using simulated problems we provide an insight into the computational performances of heuristics and the branch and bound algorithm
keyphrases: project scheduling time dependent costs branch and bound algorithm project network planning horizon project compression problem optimal schedule heuristics