Real-time order flowtime estimation methods for two-stage hybrid flowshops

In this study, we consider a problem of estimating order flowtimes in two-stage hybrid flowshops, where orders arrive dynamically and various scheduling schemes can be used. To solve the problem, we devise several order flowtime estimation methods, and each method is specific to the scheduling scheme used in the shop. Whenever an order arrives, the flowtime of the order is estimated by using one of the proposed methods. In the methods, we consider not only the current workload but also the expected workload in the near future, the volume of which mainly depends on the scheduling scheme. To evaluate the performance of the proposed methods, we obtained the actual flowtimes of orders from simulation runs, and compared them with the estimated flowtimes of the orders. The results of a series of computational experiments show the superior performance of the proposed methods over the several existing methods. & 2013 Elsevier Ltd. All rights reserved.