This study considers scheduling in Hybrid flow shop environment with unrelated parallel machines for minimizing mean of job's tardiness and mean of job's completion times. This problem does not study in the literature, so far. Flexible flow shop environment is applicable in various industries such as wire and spring manufacturing, electronic industries and production lines. After modeling the p...

We provide several non-approximability results for deterministic scheduling problems whose objective is to minimize the total job completion time. Unless P = NP, none of the problems under consideration can be approximated in polynomial time within arbitrarily good precision. Most of our results are derived by Max SNP hardness proofs. Among the investigated problems are: scheduling unrelated ma...

In this paper, the flow-shop scheduling problem with unrelated parallel machines at each stage as well as sequence-dependent setup times under minimization of the sum of earliness and tardiness are studied. The processing times, setup times and due-dates are known in advance. To solve the problem, we introduce a hybrid memetic algorithm as well as a particle swarm optimization algorithm combine...

We study a problem of optimal scheduling and lot-sizing a number of products on m unrelated parallel machines to satisfy given demands. A sequence dependent setup time is required between lots of different products. The products are assumed to be all continuously divisible or all discrete. The criterion is to minimize the time, at which all the demands are satisfied, Cmax, or the maximum latene...

This paper presents an empirical comparison of polynomial-time approximation algorithms and local search heuristics for the problem of minimizing total weighted completion time on unrelated parallel machines. Algorithms with a worst-case performance guarantee are based on rounding a fractional solution to an LP-rela....<ation or to a convex quadratic programming relaxation. We also investigate ...

Scheduling n independent jobs on m Unrelated Parallel Machines (SUM) is the problem of assigning n jobs j = 1, .., n to m machines i = 1, .., m so that each job is processed without interruption on one of the machines, and at any time, every machine processes at most one job. The objective is to minimize the makespan of the schedule. SUM is an NP-hard problem even when the number of machines is...