A new method for solving buffer allocation problem in large unbalanced production lines

Solving the buffer allocation problem (BAP) in long production lines is difficult because it is an NP-hard problem. In this paper, we propose a new approach to solve the BAP for long series-parallel unbalanced production lines with the objective of minimising the average work-in-process subject to a throughput rate constraint. Instead of directly optimising a long line, this method decomposes the original long line into several small decoupled subsystems and adds relation condition variables between the subsystems. After several iterations between subsystem optimisation and condition updating, this method can obtain the optimal or near-optimal solution of the original system with a significantly improved computational efficiency. Extensive numerical experiments demonstrate the accuracy and efficiency of this approach. Finally, several examples and a multi-factorial experimental analysis are provided to show the influence of the decomposition strategy, initial values, and parameters of the target systems on the performance of the proposed method.