An EPQ model for an imperfect production process with fuzzy cycle time and quality screening

Document Type: Research Paper


1 Suleyman Demirel University, Department of Business Administration, 32260, Isparta, Turkey

2 Suleyman Demirel University, Department of Mathematics, 32260, Isparta, Turkey

3 Suleyman Demirel University, Department of Computer Engineering, , 32260, Isparta, Turkey


This study has developed a production inventory model where the cycle time
is fuzzy, the existence of defective products is assumed in each batch and
product screening is performed both in-production and after-production.
Triangular fuzzy numbers serve to model uncertainties in the cycle time, and
a fuzzified total inventory profit function is created by the
defuzzification method known as the signed distance method. The classical
approach is used to determine the optimal policy, with the ideal cycle time
matched to the total profit. Although assuming asymmetric triangular fuzzy
numbers prevents the calculation of a clear analytical solution, the method
approaches as closely as possible to an analytical solution. A numerical
solution to only one equation is needed to obtain the optimal configuration.
Conversely, there is a positive trade-off, with an analytical solution to
the optimization problem if there is an assumption of symmetrical triangular
fuzzy numbers. The proposed model is illustrated by a numerical example. The
paper presents results and sensitivity analyses, in both tables and graphic
illustrations. The effects on total profit are discussed in relation to
various parameters. From the numerical studies, it is observed that the
level of fuzziness influences the cycle time and an approximately linear
relationship, in the opposite direction, was found between the total profit
and the level of fuzziness, when it was increased.


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