Heuristic solving 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. Each activity requires for its processing discrete resources and an amount of a continuous resource. Processing rate of an activity is a concave function of the amount of the continuous resource allotted to this activity at a time. A positive cash flow is associated with the completion of each activity. The objective is the maximization of the net present value of all cash flows of the project. Two heuristics for allocating the continuous resource are proposed, and compared to optimum on a basis of a computational experiment. Some conclusions as well as directions for future research are given.