Multi-objective flexible flow lines with due window, time lag, and job rejection

This paper presents a multi-objective flexible flow shop scheduling problem with limited time lag between stages. n jobs are available to schedule in a predetermined due window. A mixed integer linear programming model with the objectives of maximizing the total profit gained from scheduled jobs and minimizing deviation from the due date is introduced. Due to non-deterministic polynomial-time-hard complexity, the problem is solved with an efficient genetic algorithm. A heuristic mechanism is devised in every generation of the genetic algorithm to assure the solution feasibility. This heuristic also decreases the total solution time by reducing the search space. Computational results show that the presented approach finds solutions of good quality in reasonable runtimes.