Time-Cost-Quality Trade-off in Project Scheduling with fuzzy quality

Project managers often face different and sometimes conflicting goals in optimizing project resources. In recent years, the demand of the project stakeholders to reduce the total cost of the project and reduce the time and increase its quality have intensified. Therefore, the balance of time, cost, and quality are the project's main goals. These topics lead researchers to develop models that add a quality factor to previous time balance models. This research provides a model for balancing cost, time and, quality, in discrete mode. Of course, since the quality factor is not a quantitative factor-like cost and time factors, and in the real world of projects, quality is a linguistic variable. It is obtained from the point of view of experts, so in this research, the quality of activities is shown as fuzzy numbers. By finding the optimal combination (time, cost, quality) of each activity, this model compresses the activities to reduce the costs of the whole project, while achieving the desired quality. A new metaheuristic algorithm called NHGA is introduced to solve the model, which has a much higher efficiency than GA to solve model, so with a case study, the efficiency of the proposed algorithm and the flexibility of the proposed model for project managers is shown