Heuristics for the distributed blocking Ffow shop scheduling problem

Postprint (published version

Note on the blocking flow shop problem

We present some results attained with different algorithms for the Fm|block|Cmax problem using as experimental data the well-known Taillard instances

A hybrid flow shop model for an ice cream production scheduling problem

In this paper we address the scheduling problem that comes from an ice cream manufacturing company. This production system can be modelled as a three stage nowait hybrid flow shop with batch dependent setup costs. To contribute reducing the gap between theory and practice we have considered the real constraints and the criteria used by planners. The problem considered has been formulated as a mixed integer programming. Further, two competitive heuristic procedures have been developed and one of them will be proposed to schedule in the ice cream factoryPeer Reviewe

Efficient heuristic algorithms for the blocking flow shop scheduling problem with total flow time minimization

This paper proposes two constructive heuristics, i.e. HPF1 and HPF2, for the blocking flow shop problem in order to minimize the total flow time. They differ mainly in the criterion used to select the first job in the sequence since, as it is shown, its contribution to the total flow time is not negligible. Both procedures were combined with the insertion phase of NEH to improve the sequence. However, as the insertion procedure does not always improve the solution, in the resulting heuristics, named NHPF1 and NHPF2, the sequence was evaluated before and after the insertion to keep the best of both solutions. The structure of these heuristics was used in Greedy Randomized Adaptive Search Procedures (GRASP) with variable neighborhood search in the improvement phase to generate greedy randomized solutions. The performance of the constructive heuristics and of the proposed GRASPs was evaluated against other heuristics from the literature. Our computational analysis showed that the presented heuristics are very competitive and able to improve 68 out of 120 best known solutions of Taillard’s instances for the blocking flow shop scheduling problem with the total flow time criterionPeer ReviewedPostprint (author’s final draft

A note on the paper ‘Demonstrating Johnson’s algorithm via resource constrained scheduling’

In this paper we demonstrate that the relation between two jobs defined by min{ai, bj}=min{bi, aj}, used in Johnson’s theorem, is not transitive. However, both the theorem and Johnson’s algorithm are correct.Peer ReviewedPostprint (author's final draft

New insights on the blocking flow shop problem

We present some results attained with different algorithms for the Fm|block|Cmax problem using as experimental data the well-known Taillard instances.Preprin

Newinsights on the blocking flow shop problem best solutions updated

update of the best solution for Taillard's instances on the blocking flow shop problemPreprin

Efficient heuristics for the parallel blocking flow shop scheduling problem

We consider the NP-hard problem of scheduling n jobs in F identical parallel flow shops, each consisting of a series of m machines, and doing so with a blocking constraint. The applied criterion is to minimize the makespan, i.e., the maximum completion time of all the jobs in F flow shops (lines). The Parallel Flow Shop Scheduling Problem (PFSP) is conceptually similar to another problem known in the literature as the Distributed Permutation Flow Shop Scheduling Problem (DPFSP), which allows modeling the scheduling process in companies with more than one factory, each factory with a flow shop configuration. Therefore, the proposed methods can solve the scheduling problem under the blocking constraint in both situations, which, to the best of our knowledge, has not been studied previously. In this paper, we propose a mathematical model along with some constructive and improvement heuristics to solve the parallel blocking flow shop problem (PBFSP) and thus minimize the maximum completion time among lines. The proposed constructive procedures use two approaches that are totally different from those proposed in the literature. These methods are used as initial solution procedures of an iterated local search (ILS) and an iterated greedy algorithm (IGA), both of which are combined with a variable neighborhood search (VNS). The proposed constructive procedure and the improved methods take into account the characteristics of the problem. The computational evaluation demonstrates that both of them –especially the IGA– perform considerably better than those algorithms adapted from the DPFSP literature.Peer ReviewedPostprint (author's final draft

New computational experiences on the Hoist Scheduling Problem for cyclic manufacturing of different products.

Jobs of two products must receive the same treatments in a production line of tanks. If the size of both batches is equal, we propose a cyclic manufacturing composed of a job from batch 1 and a job from batch 2. A hoist ensures the transfer of the jobs between tanks. The problem consists in the scheduling of hoist movements, which is known as HSP (Hoist Scheduling Problem). There is a comparison between completely separated and mixed production for both batches. The objective is to determine a sequence which minimises the cycle time for two jobs from different products (2-product cycle). We propose a branch-and-bound procedure, which can also be applied to the 2-cycle case for a single product. The model can be extended to ncycles

A new constructive heuristic for the Fm|block|¿T

This paper deals with the blocking flow shop problem and proposes new constructive procedure s for the total tardiness minimization of jobs. The heuristic has three - phases to build the sequence; the first phase selects the first job to be scheduled, the second phase ar ranges the remaining jobs and the third phase uses the insertion procedure of NEH to improve the sequence. T he proposed proce- dures evaluate the tardiness associated to the sequence obtained before and after the third phase in order to keep the best of both because , we have observed , that the insertion phase can worsen the result . The c omputational evaluation of these procedures against the benchmark constructive procedures from the literature re- veals their good performancePostprint (published version