Browsing by Subject "Cellular manufacturing"

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    Analysis of Lagrangian lower bounds for a graph partitioning problem
    (Institute for Operations Research and the Management Sciences (INFORMS), 1999) Adil, G. K.; Ghosh, J. B.
    Recently, Ahmadi and Tang (1991) demonstrated how various manufacturing problems can be modeled and solved as graph partitioning problems. They use Lagrangian relaxation of two different mixed integer programming formulations to obtain both heuristic solutions and lower bounds on optimal solution values. In this note, we point to certain inconsistencies in the reported results. Among other things, we show analytically that the first bound proposed is trivial (i.e., it can never have a value greater than zero) while the second is also trivial for certain sparse graphs. We also present limited empirical results on the behavior of this second bound as a function of graph density.
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    Cellular manufacturing system design using a holonistic approach
    (Taylor & Francis, 2000) Aktürk, M. S.; Türkcan, A.
    We propose an integrated algorithm that will solve the part-family and machine-cell formation problem by simultaneously considering the within-cell layout problem. To the best of our knowledge, this is the first study that considers the efficiency of both individual cells and the overall system in monetary terms. Each cell should make at least a certain amount of profit to attain self-sufficiency, while we maximize the total profit of the system using a holonistic approach. The proposed algorithm provides two alternative solutions; one with independent cells and the other one with inter-cell movement. Our computational experiments indicate that the results are very encouraging for a set of randomly generated problems.
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    Dynamic lot sizing and scheduling in cellular manufacturing systems using hybrid simulation analytic model
    (International Journal of Industrial Engineering, 1995) Aktürk, M. S.; Dağlıoğlugil, O.
    In most of the production systems, lot-sizing and scheduling decisions are made at different levels of hierarchy; although there is a strong interaction between these decisions. Furthermore, most of the existing models do not utilize the shop floor conditions in lot-sizing and scheduling decisions, even though such a decision might improve the system performance. In this study, a dynamic lot-sizing and scheduling algorithm is suggested for cellular manufacturing systems, which utilizes a hybrid simulation/analytic modeling approach. The performance of the proposed algorithm is tested against the push and pull systems under different shop floor conditions, and shown that we can improve tardiness, flow time and makespan criteria when comparedto other systems.
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    A multi-family dynamic lot sizing problem with coordinated replenishments: a heuristic procedure
    (Taylor & Francis, 1993) Mercan, H. M.; Erenguc, S. S.
    Consider a manufacturing environment where multiple items are produced. These products are grouped into families due to their similarities in design and manufacturing. It pays off to coordinate the manufacture of products in a given family because preparing the facility for producing a family of products involves a major family setup. In addition each individual product in a given family may require a relatively minor setup. The objective is to determine the product lot sizes, over a finite planning horizon, that will minimize the total relevant cost, subject to demand and capacity constraints. In this paper we present an effective heuristic procedure for this problem. Computational results for the heuristic procedure are also reported. Our computational experience leads us to conclude that the heuristic procedure may be of considerable value as a decision making aid to production planners in a real-world setting.
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    A note on the within-cell layout problem based on operation sequences
    (Taylor & Francis, 1996) Aktürk, M. S.
    The existing studies in the literature usually ignore the within-cell layout problem while forming part families and manufacturing cells. A new approach is proposed to solve the part-family and machine-cell formation problem and to determine the spatial arrangement of machines in each cell simultaneously. Furthermore, a dissimilarity measure between parts based on operation sequences is presented since the operation sequences not only specify the type of machine tools needed but also impact the flow of material. As a result, we can both minimize the material handling cost and streamline the material flow in each cell.
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    Tepe Mobilya' da hücresel üretimle teslimat sürelerinin kısaltılması
    (TMMOB, 2006) Bozkurt, C. Halil; Çınar, Yüce; Kayayurt, Bade; Sevinçli, Berna; Tamer, Ş. Okan; Usluoğlu, A. Deniz; Aktürk, M. Selim
    Tepe Mobilya Fabrikası'nda döşemeli ürünlerin teslimat sürelerinin azaltılması fabrika ve ürünlerin satışlarını gerçekleştiren Tepe Home için büyük önem taşımaktadır. Bu projede fabrikanın hücresel üretime geçişi için bir yöntembilim geliştirildikten sonra, hücreler arası ve hücre içi değişkenliği enazlayacak işçi atama probleminin çözümü için bir matematiksel model geliştirilmiş ve bu modelin çözümüyle en iyi hücre sayısı ve her bir hücreye atanacak makine ve işçi sayıları belirlenmiştir. Önerilen çözüm setinden alınan bir hücre ve işçi atama sonucu belirlenen bir pilot hücrede uygulanmış, olumlu sonuçlar alınmış ve bu yöntembilimi destekleyen web tabanlı olarak çalışabilen PHP programlama dili ve Oracle 9.2 veritabanının kullanıldığı "Üretim Takip ve Bilgilendirme Sistemi" programı hazırlanmıştır. Geliştirilen bu yöntembilim ile döşemeli ürünlerin teslimat sürelerinde İstanbul siparişleri için %14,5'lik, Ankara siparişleri içinse %8,29'luk bir azalma sağlanabileceği gösterilmiştir.