Yazar "Demirel, Neslihan" seçeneğine göre listele

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    A genetic algorithm approach for optimising a closed-loop supply chain network with crisp and fuzzy objectives
    (TAYLOR & FRANCIS LTD, 2014) Demirel, Neslihan; Ozceylan, Eren; Paksoy, Turan; Gokcen, Hadi
    This paper proposes a mixed integer programming model for a closed-loop supply chain (CLSC) network with multi-periods and multi-parts under two main policies as secondary market pricing and incremental incentive policies. In the first policy, customers order and receive products from distribution centres, but at next period, they can trade among themselves with used products that are returned in a secondary market. Financial incentives are offered to the customers to influence the returns, and the correct amount of collections at different prices is determined by the second policy. In addition to the base case (crisp) formulation, a fuzzy multi-objective extension is applied to solve CLSC network problem with fuzzy objectives to represent vagueness in real-world problems. Then, developed genetic algorithm approach is applied to solve real size crisp and fuzzy CLSC problems. The effectiveness of the proposed meta-heuristic approach is investigated and illustrated by comparing its results with GAMS-CPLEX on a set of crisp/fuzzy problems with different sizes.
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    An integrated model to incorporate ergonomics and resource restrictions into assembly line balancing
    (TAYLOR & FRANCIS LTD, 2014) Kara, Yakup; Atasagun, Yakup; Gokcen, Hadi; Hezer, Seda; Demirel, Neslihan
    This study incorporates ergonomics and resource restrictions into assembly line balancing (ALB). For this purpose, an integrated model is proposed. The proposed model is essentially a cost-oriented formulation for ALB under psychological strain, physical strain, worker skills, multiple workers, equipment, working postures and illumination level restrictions. The integrated nature of the proposed model is one of its distinctive features in ALB literature. In addition, the proposed model modifies the existing restrictions by means of real-life facts and introduces two new restrictions arisen from the industry that have not been addressed in the literature. The model minimises the overall cost associated with operating costs of workforce and resources utilised under the ergonomics and resource restrictions. The model is illustrated and validated using some examples.