A Fuzzy CDS-based Scheduling Algorithm for More Than Two Machine Centers

Author(s):  
Tzung-Pei Hong ◽  
◽  
Tzu-Ting Wang ◽  
Shyue-Liang Wang ◽  

In simple flow shop problems, each machine operation center includes just one machine. If at least one machine center includes more than one machine, the scheduling problem becomes a flexible flow-shop problem. Flexible flow shops can thus be thought of as generalizations of simple flow shops. In Ref.14), we have demonstrated how fuzzy concepts can easily be used in the Sriskandarajak and Sethi’s algorithm for managing uncertain scheduling on two-machine centers. This paper extends application to fuzzy flexible flow-shops with more than two machine centers. A new fuzzy heuristic flexible flowshop scheduling algorithm is then designed since optimal solutions seem unnecessary for uncertain environments. We first use fuzzy LPT algorithm to allocate jobs into the groups and then use the fuzzy CDS algorithm to deal with sequencing the tasks. The proposed method thus provides a flexible way to more fit real world applications.

Author(s):  
Tzung-Pei Hong ◽  
◽  
Wei-Chou Chen ◽  

In simple-flow shop problems, each machine operation center has one machine. If a machine center has more than one machine, scheduling becomes a flexible shop flow problem. Flexible shop flows are thus generalizations of simple shop flow. Processing time for each job was previously assumed to be known exactly, but in many real-world applications, processing times vary dynamically due to human or operating factors. We apply fuzzy concepts to represent uncertainty in processing times for flexible-flow shops with two machine centers, then propose a fuzzy heuristic algorithm for job scheduling. We first use a fuzzy LPT algorithm to allocate jobs, then use a fuzzy Johnson algorithm to deal with task sequencing. The proposed method lets jobs be scheduled more flexibly than conventionally.


2014 ◽  
Vol 39 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Enrique Gerstl ◽  
Gur Mosheiov ◽  
Assaf Sarig

Abstract We study a special two-stage flexible flowshop, which consists of several parallel identical machines in the first stage and a single machine in the second stage. We assume identical jobs, and the option of batching, with a required setup time prior to the processing of a new batch. We also consider the option to use only a subset of the available machines. The objective is minimum makespan. A unique optimal solution is introduced, containing the optimal number of machines to be used, the sequence of batch sizes, and the batch schedule. The running time of our proposed solution algorithm is independent of the number of jobs, and linear in the number of machines


2013 ◽  
Vol 161 (13-14) ◽  
pp. 2107-2119 ◽  
Author(s):  
D. Prot ◽  
C. Rapine

1981 ◽  
Vol 29 (2) ◽  
pp. 400-411 ◽  
Author(s):  
Wlodzimierz Szwarc

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