Browsing by Author "Goren, Hacer Guner"

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Citation - WoS: 4
Citation - Scopus: 4
A Comparative Study of Hybrid Approaches for Solving Capacitated Lot Sizing Problem With Setup Carryover and Backordering
(Inderscience Enterprises Ltd, 2016) Goren, Hacer Guner; Tunali, Semra
The classical capacitated lot sizing problem is shown to be NP -hard for even a single item problem. This study deals with an extended version of this problem with setup carryover and backordering. To solve this computationally difficult lot sizing problem, we propose a number of hybrid meta -heuristic approaches consisting of genetic algorithms and a mixed integer programming -based heuristic. This MIP-based heuristic is combined with two types of decomposition schemes (i.e., product and time decomposition) to generate subproblems. Computational experiments are carried out on various problem sizes. We found that hybrid approaches employing only time decomposition scheme or combination of both time and product decomposition schemes in different forms outperform the other hybrid approaches. Moreover, we investigated the sensitivity of the two best performing approaches to changes in problem-specific parameters including backorder costs, setup times, setup costs, capacity utilisation and demand variability.
Citation - WoS: 4
Fix-And Heuristics for Capacitated Lot Sizing With Setup Carryover and Backordering
(Emerald Group Publishing Ltd, 2018) Goren, Hacer Guner; Tunali, Semra
Purpose The capacitated lot sizing problem (CLSP) is one of the most important production planning problems which has been widely studied in lot sizing literature. The CLSP is the extension of the Wagner-Whitin problem where there is one product and no capacity constraints. The CLSP involves determining lot sizes for multiple products on a single machine with limited capacity that may change for each planning period. Determining the right lot sizes has a critical importance on the productivity and success of organizations. The paper aims to discuss these issues. Design/methodology/approach This study focuses on the CLSP with setup carryover and backordering. The literature focusing on this problem is rather limited. To fill this gap, a number of problem-specific heuristics have been integrated with fix-and-optimize (FOPT) heuristic in this study. The authors have compared the performances of the proposed approaches to that of the commercial solver and recent results in literature. The obtained results have stated that the proposed approaches are efficient in solving this problem. Findings The computational experiments have shown that the proposed approaches are efficient in solving this problem. Originality/value To address the solution of the CLSP with setup carryover and backordering, a number of heuristic approaches consisting of FOPT heuristic are proposed in this paper.
Citation - WoS: 26
Citation - Scopus: 30
A Hybrid Approach for the Capacitated Lot Sizing Problem With Setup Carryover
(Taylor & Francis Ltd, 2012) Goren, Hacer Guner; Tunali, Semra; Jans, Raf
The capacitated lot sizing problem with setup carryover deals with the issue of planning multiple products on a single machine. A setup can be carried over from one period to the next by incorporating the partial sequencing of the first and last product. This study proposes a novel hybrid approach by combining Genetic Algorithms (GAs) and a Fix-and-Optimise heuristic to solve the capacitated lot sizing problem with setup carryover. Besides this, a new initialisation scheme is suggested to reduce the solution space and to ensure a feasible solution. A comparative experimental study is carried out using some benchmark problem instances. The results indicate that the performance of the pure GAs improves when hybridised with the Fix-and-Optimise heuristic. Moreover, in terms of solution quality, promising results are obtained when compared with the recent results in the literature.
Citation - WoS: 12
Citation - Scopus: 11
Solving the Capacitated Lot Sizing Problem With Setup Carryover Using a New Sequential Hybrid Approach
(Springer, 2015) Goren, Hacer Guner; Tunali, Semra
The aim of lot sizing problems is to determine the periods where production takes place and the quantities to be produced in order to satisfy the customer demand while minimizing the total cost. Due to its importance on the efficiency of the production and inventory systems, lot sizing problems are one of the most challenging production planning problems and have been studied for many years with different modelling features. Among these problems, the capacitated lot sizing problem (CLSP) has received a lot of attention from researchers. Having motivated from our earlier study, this study proposes a new hybrid approach for solving the CLSP with the extension of setup carryover. Moreover, the initialization scheme proposed in the earlier study has also been investigated comprehensively. Lastly, an experimental study evaluating the solution quality of the proposed approach is carried out using various problem instances and promising results are obtained when compared to the recent results in the literature.