Kybernetika 47 no. 1, 50-59, 2011

Hybrid flow-shop with adjustment

Jan Pelikán


The subject of this paper is a flow-shop based on a case study aimed at the optimisation of ordering production jobs in mechanical engineering, in order to minimize the overall processing time, the makespan. The production jobs are processed by machines, and each job is assigned to a certain machine for technological reasons. Before processing a job, the machine has to be adjusted; there is only one adjuster who adjusts all of the machines. This problem is treated as a hybrid two-stage flow-shop: the first stage of the job processing is represented by the machine adjustment for the respective job, and the second stage by the processing of the job itself on the adjusted machine. In other words, the job-processing consists of two tasks, where the first task is the machine adjustment for the job, and the second task is the job processing itself. A mathematical model is proposed, a heuristic method is formulated, and the NP hardness of the problem, called a "hybrid flow-shop with adjustment," is proved.


heuristics, flow-shop, case study, integer programming


90B35, 90B90


  1. J. Blazewicz, K. H. Ecker, E. Pesch, G. Schmidt and J. Weglarz: Scheduling Computer and Manufacturing Processes. Springer-Verlag, Berlin 1996.   CrossRef
  2. Y. Cho and S. Sahni: Preemptive scheduling of independent jobs with release and due times on open, flow and job shops. Oper. Res. 29 (1981), 3, 511-522.   CrossRef
  3. M. Kubzin and A. Strusevich: Planning machine maintenance in two-machine shop scheduling. Oper. Res. 54, 4, 2006, 789-800.   CrossRef
  4. J. K. Lenstra and A. H. G. Rinnooy Kan: Complexity of scheduling under precedence constraints. Oper. Res. 26 (1978), 1, 22-35.   CrossRef