A two-stage and three-stage no-wait hybrid flow shop(NWHFS) scheduling problem is considered against a background of the scheduling problem of roller annealing operation in cast steel plant of a roller corporation.For the no-wait constraint between two sequential operations of a job,the no-wait algorithm of grading(NWAG) is designed.On this basis,we tried to combine NWAG with the discrete particle swarm optimization(DPSO) algorithm to solve the built integer programming model.In the simulation e...