Abstract
Springer would like to retract the article "The Hafshejani et al." published in Journal of Industial Engineering International (2012, 8:27). The article was mistakenly published due to a workflow error although it had not been accepted by the Editorial Board of the journal. Springer accepts full responsibility for this and would like to apologize to the authors of the article as well as the Editors and readers of the journals. The Economic Production Quantity (EPQ) model is often used in the manufacturing sector to assist firms in determining the optimal production lot size that minimizes overall production-inventory costs. There are some assumptions in the EPQ model that restrict this model for real-world applications. Some of these assumptions are (1) infinite space of warehouse, (2) all of the produced items are perfect, and (3) only one type of goods is produced. In this paper, we develop the EPQ model by assuming that each produced lot contains some imperfect items and scraps. In addition, we have more than one kind of products along with warehouse space limitations. Under these conditions, we formulate the problem as a non-linear programming model and propose a genetic algorithm to solve it. At the end, we present a numerical example to illustrate the applications of the proposed methodology and identify the optimal value of the parameters of the genetic algorithm.
Highlights
The Economic Production Quantity (EPQ) model can be considered as an extension to the well-known Economic Order Quantity (EOQ) model, and it is a technique to find out optimum production quantity by considering costs of procurement, inventory holding, and shortage
We present a numerical example to illustrate the applications of the proposed methodology and identify the optimal value of the parameters of the genetic algorithm
A numerical example In order to demonstrate the application of the proposed genetic algorithm, we present a numerical example
Summary
The Economic Production Quantity (EPQ) model can be considered as an extension to the well-known Economic Order Quantity (EOQ) model, and it is a technique to find out optimum production quantity by considering costs of procurement, inventory holding, and shortage. As the first assumptions of the EPQ model may not be valid for many real-life conditions, many researchers have developed EOQ and EPQ models. In real-life manufacturing systems, generation of defective items is inevitable. Many researchers consider producing defective items in EOQ and EPQ models. Hayek and Salameh (2001) assumed that all of the defective items produced are repairable and derived an optimal operating policy for the EPQ model. The basic model assumed that shortage is not permitted. In real-life manufacturing systems, generation of defective items and random breakdown of production equipment are inevitable
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