Multi-project scheduling with two-stage decomposition

A non-preemptive, zero time lag multi-project scheduling problem with multiple modes and limited renewable and nonrenewable resources is considered. A 2stage decomposition approach is adopted to formulate the problem as a hierarchy of 0-1 mathematical programming models. At stage one; each project is reduced to a macro-activity with macro-modes. The macro-activities are combined into a single macro-activity network over which the macro-activity scheduling problem (MP) is defined, where the objective is the maximization of the net present value with positive cash flows and renewable resource requirements are time-dependent. An exact solution procedure and a genetic algorithm (GA) approach are proposed for solving MP. GA is also employed to generate an initial solution for the exact solution procedure. The first stage terminates with a post-processing procedure to distribute the remaining resource capacities. Using the start times and the resource profiles obtained in stage one each project is scheduled in stage two for minimum makespan. Three new test problem sets are generated with 81, 84 and 27 problems each and three different configurations of solution procedures are tested.