Bi-objective Fuzzy Mathematical Models in a Labor-Intensive Cell

In this paper, a bi-objective fuzzy model for a single product multi-period scheduling problem is discussed. The objectives of the fuzzy model are maximizing the customer satisfaction while minimizing the manpower level in a labor-intensive environment. Two options are considered for the proposed mathematical model. In the first one, the manpower level is allowed to vary from one period to the next. Therefore, the model selects the best manpower level for each period based on the customer demand in that period. In the second option, the manpower level is kept the same in each period. In this situation, the critical decision is to determine the optimal manpower configuration to avoid resources' idle time and shortage simultaneously. For simplification, time-varying but deterministic demand values are considered. Similarly, processing times are also assumed to be deterministic. The fuzzy function used in our approach is the minimum bounded sum which is achieved by setting bound limits for each of the fuzzy parameters. In the experiment and results section, a small problem taken from a case study is solved considering both options and multiple bound limits. (C) 2018 The Authors. Published by Elsevier B.V.