Local search metaheuristics for some discrete-continuous project scheduling problems with discounted cash flows

In this paper a discrete-continuous project scheduling problem with discounted cash flows is considered. In discrete-continuous project scheduling activities require for their processing discrete and continuous resources. Processing rate of an activity depends on the amount of the continuous resource allotted to this activity at a time. A positive cash flow is associated with each activity. A common payment model - payments at activity completion times is considered. The objective is the maximization of the net present value of all cash flows of the project. Applications of two local search metaheuristics - simulated annealing and tabu search are described. The algorithms are compared on the basis of a computational experiment, the results are analyzed and discussed. Some conclusions as well as directions for further research are given.