Mathematical models and decomposition algorithms for makespan minimization in plastic rolls production
研究了吹膜挤出工艺中塑料卷生产的切割与调度联合优化问题，提出数学模型和分解启发式算法，通过实验验证了小规模实例可获最优解，大规模实例中迭代局部搜索算法效果良好。
We study an optimization problem that originates from the packaging industry, and in particular in the process of blown film extrusion, where a plastic film is used to produce rolls of different dimensions and colors. The film can be cut along its width, thus producing multiple rolls in parallel, and setup times must be considered when changing from one color to another. The optimization problem that we face is to produce a given set of rolls on a number of identical parallel machines by minimizing the makespan. The problem combines together cutting and scheduling decisions and is of high complexity. For its solution, we propose mathematical models and heuristic algorithms that involve a nontrivial decomposition method. By means of extensive computational experiments, we show that proven optimality can be achieved only on small instances, whereas for larger instances good quality solutions can be obtained especially by the use of an iterated local search algorithm.