Providing a robust integrated model of material ordering and project scheduling with limited resources under uncertainty

Abstract

Today, with the complexity of the economic conditions and the competitive conditions governing the receipt and implementation of projects, the importance of detailed planning to achieve goals in project-oriented organizations has been well demonstrated. One of the most important of these plans is the project schedule, which, due to its importance, is an attractive research field for the use of optimization methods among researchers in the science of operations research. In the present research, the integrated problem of material ordering and project scheduling in the conditions of resource limitations, uncertainty and calendar interruptions was examined. Simultaneous consideration of discount issues, non-renewability, corruption, uncertainty and different scenarios of project implementation made the model closer to the real world conditions and as a result the results obtained from it became more practical. Therefore, a scenario-based model was designed with the objective function of minimizing the total costs (including ordering, maintenance, purchase and delay penalty minus the bonus for speeding up the project delivery) and then the stabilization of the model was done with a feasibility approach. After presenting the model, numerical problems were designed and solved in different dimensions using GAMS software and the results were discussed.