Metaheuristics for multi-mode capital-constrained project payment scheduling
This paper involves the multi-mode capital-constrained project payment scheduling problem, where the objective is to assign activity modes and payments so as to maximize the net present value (NPV) of the contractor under the constraint of capital availability. In the light of different payment patterns adopted, four optimization models are constructed using the event-based method. For the NP-hardness of the problem, metaheuristics, including tabu search and simulated annealing, are developed and compared with multi-start iterative improvement and random sampling based on a computational experiment performed on a data set generated randomly. The results indicate that the loop nested tabu search is the most promising procedure for the problem studied. Moreover, the effects of several key parameters on the contractors NPV are investigated and the following conclusions are drawn: The contractors NPV rises with the increase of the contractors initial capital availability, the payment number, the payment proportion, or the project deadline; the contractor has a decreasing marginal return as the contractors initial capital availability goes up; the contractors NPVs under the milestone event based payment pattern are not less than those under the other three payment patterns.
metaheuristics payments net present value project scheduling capital constraint