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Papers by Kursad Agpak

Applied Soft Computing, Dec 1, 2017

Robotic assembly line Robotic parallel assembly lines Highlights  This is the first adaptation o... more Robotic assembly line Robotic parallel assembly lines Highlights  This is the first adaptation of beam search algorithm to solve the RALB problem  This is the first study which models a parallel RALB problem.  Three different heuristic approaches based on beam search are developed  The algorithm was thoroughly tested on small and large sized instances  Comparison with DE and PSO proves the superiority of the proposed method  The algorithm provides near optimal solution for this NP-complete problem Abstract-In a robotic assembly line, a series of stations are arranged along a conveyor belt and a robot performs on tasks at each station. Parallel assembly lines can provide improving line balance, productivity and so on. Combining robotic and parallel assembly lines ensure increasing flexibility of system, capacity and decreasing breakdown sensitivity. Although aforementioned benefits, balancing of robotic parallel assembly lines is lackingto the best knowledge of the authors-in the literature. Therefore, a mathematical model is proposed to define/solve the problem and also iterative beam search (IBS), best search method based on IBS (BIBS) and cutting BIBS (CBIBS) algorithms are presented to solve the large-size problem due to the complexity of the problem. The algorithm also tested on the generated benchmark problems for robotic parallel assembly line balancing problem. The superior performances of the proposed algorithms are verified by using a statistical test. The results show that the algorithms are very competitive and promising tool for further researches in the literature.

Endüstri Mühendisliği, 2001

In this paper, a goal programming model for the simple U-line balancing (ULB) problem is develope... more In this paper, a goal programming model for the simple U-line balancing (ULB) problem is developed. The model is based on the integer programming formulation developed by Urban [Urban, Note: Optimal balancing of U-shaped assembly lines, Management Science 44(5) (1998) 738–741] for the ULB problem and the goal model of Deckro and Rangachari [Deckro, Rangachari, A goal approach to assembly line balancing, Computers and Operations Research 17 (1990) 509–521] developed for the traditional single model assembly line balancing (ALB) problem. The proposed model which is the first multi-criteria decision making approach to the U-line version provides increased flexibility to the decision maker since several conflicting goals can be simultaneously considered. 2004 Elsevier B.V. All rights reserved.

Bu makalede, gorev zamanlarinin normal dagilimla ifade edildigi (stokastik) U tipi montaj hatti d... more Bu makalede, gorev zamanlarinin normal dagilimla ifade edildigi (stokastik) U tipi montaj hatti dengelenme problemi icin yeni bir sezgisel prosedur onerilmistir. Onerilen prosedur gelistirilirken, Arcus [16] tarafindan geleneksel, deterministik tek modelli hatlar icin sunulan COMSOAL metodundan faydalanilmistir. Prosedur, herbir istasyon icin yonetim tarafindan belirlenen guvenlik seviyesi kisiti altinda, gorevlerin, istasyon sayisi enkucuklenecek sekilde atanmalarini amaclamaktadir. Prosedur, Pascal programlama diliyle kodlanmis, degisik test problemleriyle denenmis ve sonuclar tartisilmistir.

International Journal of Production Research, 2018

The optimisation problems related to the assignment of tasks to workstations in assembly and disa... more The optimisation problems related to the assignment of tasks to workstations in assembly and disassembly lines have been largely discussed in the literature. They are known, respectively, as Assembly Line Balancing and Disassembly Line Balancing Problems. In this study, both types of task performed on the identical product are integrated in a common hybrid production system. Therefore, the logistic process is simplified and disassembly tasks can supply easier the assembly tasks with the required components. The considered production system has the layout of two parallel lines with common workstations. The product flow is conventional in the assembly line and reverse in the disassembly line. The paper provides a new mathematical model for designing such a hybrid system and an approximate approach based on ant colony optimisation for solving large-scale instances. The solution method is tested in a case study. The obtained results are compared with the solution provided by the design of two independent lines. The analysis of the results highlights the potential benefits of the hybrid production system.

Journal of Manufacturing Systems, 2016

The disassembly line balancing (DLB) problem is the process of allocating a set of disassembly ta... more The disassembly line balancing (DLB) problem is the process of allocating a set of disassembly tasks to an ordered sequence of workstations in such a way that optimizes some performance measures (e.g., cycle time, number of stations). Since DLB problems belong to the class of NP hard, many heuristic and meta-heuristic algorithms are applied to cope with the complexity of the DLB problems in order to obtain acceptable solutions in a reasonable amount of time. In this study, a beam search (BS) based approach for the DLB problem is proposed. Minimization of number of workstations is used as the performance measure. The proposed algorithm is compared with the optimal solutions of well-known real cases and generated test problems. The results indicate that the proposed approach based on BS is a very competitive and promising tool for further researches.

IFAC-PapersOnLine, 2016

Abstract The disassembly line balancing (DLB) problem is the process of allocating a set of disas... more Abstract The disassembly line balancing (DLB) problem is the process of allocating a set of disassembly tasks to an ordered sequence of workstations in such a way that optimizes some performance measures (e.g., number of stations, hazardous components number, cycle time and work load). When disassembly operations are done on disassembly line, sometimes they need specific resources such as a robot, equipment, material, specific machine or qualified staff while working at the workstation. This issue also raises resource constrained disassembly line balancing (RCDLB) problem. Therefore, in this study, a mathematical model is presented for DLB problem by considering resource constraints. The objective is to minimize the number of resources and workstations under determined cycle time. The mathematical model is solved by using a mathematical programming package called as GAMS-CPLEX. Two examples from literature are solved and analyzed in order to test validity of the proposed model.

IFAC-PapersOnLine, 2016

Abstract In the assembly system, robots are able to provide enhancement on flexibility of the sys... more Abstract In the assembly system, robots are able to provide enhancement on flexibility of the system and automation. Each robot can perform different performance on the same tasks due to their capabilities. Therefore, the balancing robotic assembly line (RALB) problem consists two main works, which are assigning tasks to workstations, and allocation robots in workstations. On the other hand, robot cost is another important factor on selection of type of robot due to the high capital investment. In this study, the conflict objectives, minimizing cycle time, number of workstation and robot cost, are considered. The goal programming approach is proposed to satisfy these objectives. Behavior of the proposed approach is analyzed on an example.

Pamukkale University Journal of Engineering Sciences, 2015

Montaj hattı dengeleme literatüründe hazırlık zamanlarını dikkate alan sınırlı sayıda çalışma bul... more Montaj hattı dengeleme literatüründe hazırlık zamanlarını dikkate alan sınırlı sayıda çalışma bulunmaktadır. Aynı zamanda bu çalışmalarda hazırlık zamanlarının deterministik olduğu varsayılmıştır. Fakat gerçek uygulamalarda görev ve hazırlık zamanları insan faktörü, makine arızaları, donanım eksikliği ve çevresel faktörler gibi nedenlerden dolayı değişkenlik gösterebilmektedir. Bu nedenle, çalışmada stokastik sıra-bağımlı hazırlık zamanlarını dikkate alan montaj hattı dengeleme problemi incelenmiştir. Problemin çözümüne yönelik bir matematiksel model önerilmiş ve belirli test problemleri üzerinde hesaplama analizleri yapılmıştır. There is limited number of papers which consider setup times in assembly line balancing literature. Additionally, in these studies setup times are assumed as deterministic. Nevertheless, task and setup times can include variation due to human factors, machine breakdowns, lack of equipment and environmental factors in real life applications. Therefore, in this study assembly line balancing problem with stochastic sequence-dependent setup time is studied. A mathematical model is proposed for solving the problem and computational analysis is made on certain test problems.

Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, Mar 5, 2014

Büyük boyutlu otobüs, kamyon, otomobil gibi ürünlerin montaj işlemleri hattın her iki tarafında y... more Büyük boyutlu otobüs, kamyon, otomobil gibi ürünlerin montaj işlemleri hattın her iki tarafında yapılabilmektedir. Böyle durumlarda hattın her iki tarafı (hem sağ hem sol) kullanılarak montaj işlemi yapılır. Bu tip hatlar çift taraflı montaj hattı olarak isimlendirilir. Büyük hacimli ürünler üretilirken bazen özellikli bir makineye veya bu makineyi kullanabilecek kalifiye bir personele ihtiyaç duyulabilir. Bu durum kaynak kısıtı sorununu ortaya çıkarmaktadır. Bu yüzden literatürdeki modeller temel alınarak genelleştirilmiş kaynak kısıtlı çift taraflı montaj hattı dengeleme problemi için bir matematiksel model sunulmuş ve çok amaçlı durum için hesaplama analizleri yapılmıştır. Sunulan model 3 farklı amaç fonksiyonu (istasyon sayısı, pozisyon sayısı ve kaynak maliyetinin en küçüklenmesi) ile test problemleri üzerinde çalıştırılmış ve sonuçlar analiz edilmiştir.

Savunma bilimleri dergisi, Mar 1, 2003

Bu makalede, basit U tipi montaj hattı dengeleme problemleri için bir bulanık tamsayılı programla... more Bu makalede, basit U tipi montaj hattı dengeleme problemleri için bir bulanık tamsayılı programlama (U-FP) modeli geliştirilmiştir. Amaç çevrim zamanı, istasyon sayısı ve iş yükü gibi sağ taraf değişkenlerin belirsiz olduğu durumlarda karar vericiye çözüm sunabilmektir. Bu çalışma, U tipi montaj hattı literatüründeki ilk bulanık tamsayılı programlama çalışmasıdır. In this paper, a fuzzy integer programming model (U-FP) for the simple U shaped assembly line balancing problems is developed. The purpose of the model developed here is to provide a solution to the decision maker for uncertainty cases of cycle time, number of stations and work load values. This study is the first on fuzzy integer programming in the U shaped assembly line literature.

Transactions of the Canadian Society for Mechanical Engineering, 2010

This study introduces a new hybrid design for a specific case of assembly lines, and proposes a m... more This study introduces a new hybrid design for a specific case of assembly lines, and proposes a multi-pass random assignment algorithm to find the minimum number of stations required. The algorithm also finds the sequence and the schedule of the tasks assigned. The new design is a combination of two-sided lines and U-shaped lines, which benefits from the advantages of both designs at the same time. One side of the line is arranged in U-shape allowing stations with crossovers, and the other side of the line is balanced like a traditional straight flow. Depending on product direction, either Left or Right side of the line can be designed in U-shape. Small and large-sized two-sided assembly line test-bed problems were solved using the algorithm. Optimal results are achieved for all small-sized problems. Due to the novelty of the design, results of largesized problems are compared to findings of studies on simple two-sided balancing. Algorithm produced better results in most of the cases.

Engineering Optimization, 2016

ArXiv, 2016

Smart phone and tablet usage has sharply increased for the last decade. While entering test on th... more Smart phone and tablet usage has sharply increased for the last decade. While entering test on these devices, virtual keyboards are generally used instead of conventional hardware keyboards. In this study, a new problem which is two-finger keyboard layout problem and solution approach is presented for increasing user test entrance performance, especially on virtual keyboards. Defined two-finger keyboard layout problem is modeled as Quadratic Assignment Problem. Because of combinatorial structure of the problem a genetic algorithm is developed. Its result is given to mathematical model as initial solution for finding better solutions with mathematical model. Proposed approach is applied on Turkish language. The new two finger keyboard layout for Turkish language is compared with F and QWERTY keyboard layouts based on certain performance measurement techniques.

Pamukkale University Journal of Engineering Sciences, Jun 12, 2011

... veya tüketilmeden önce genellikle test edilemezler (Lewis and Booms, 1983; Garvin, 1984; Fitz... more ... veya tüketilmeden önce genellikle test edilemezler (Lewis and Booms, 1983; Garvin, 1984; Fitzsimmons and Mona, 1994; Erkut, 1995). ... Böylece, üretim sistemleri için geliştirilen daha pekçok metodun, hizmet sistemlerinde karşılık bulacağı ve pratik uygulamalar açısından önem ...

International Journal of Production Research, 2014

ABSTRACT doi: 10.1080/00207543.2014.955218

U-type and two-sided assembly lines are two types of design having advantages over traditional st... more U-type and two-sided assembly lines are two types of design having advantages over traditional straight assembly lines. In this paper, a new line design hybrid of U-type and two-sided lines is presented. A bi-objective 0-1 integer programming model is developed to solve the line balancing problem of the proposed design. Zoning constraints are also considered for the proposed design. A number of test problems from the literature with up to 65 tasks are solved. Benefits of two-sided U-type lines are discussed.

This study introduces a new hybrid design for a specific case of assembly lines, and proposes a m... more This study introduces a new hybrid design for a specific case of assembly lines, and proposes a multi-pass random assignment algorithm to find the minimum number of stations required. The algorithm also finds the sequence and the schedule of the tasks assigned. The new design is a combination of two-sided lines and U-shaped lines, which benefits from the advantages of both designs at the same time. One side of the line is arranged in U-shape allowing stations with crossovers, and the other side of the line is balanced like a traditional straight flow. Depending on product direction, either Left or Right side of the line can be designed in U-shape. Small and large-sized two-sided assembly line test-bed problems were solved using the algorithm. Optimal results are achieved for all small-sized problems. Due to the novelty of the design, results of large sized problems are compared to findings of studies on simple two-sided balancing. Algorithm produced better results in most of the cases.

ABSTRACT This study introduces a new hybrid design for a specific case of assembly lines, and pro... more ABSTRACT This study introduces a new hybrid design for a specific case of assembly lines, and proposes a multi-pass random assignment algorithm to find the minimum number of stations required. The algorithm also finds the sequence and the schedule of the tasks assigned. ...

Applied Soft Computing, Dec 1, 2017

Endüstri Mühendisliği, 2001

International Journal of Production Research, 2018

Journal of Manufacturing Systems, 2016

IFAC-PapersOnLine, 2016

Pamukkale University Journal of Engineering Sciences, 2015

Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi, Mar 5, 2014

Savunma bilimleri dergisi, Mar 1, 2003

Transactions of the Canadian Society for Mechanical Engineering, 2010

Engineering Optimization, 2016

ArXiv, 2016

Pamukkale University Journal of Engineering Sciences, Jun 12, 2011

International Journal of Production Research, 2014

ABSTRACT doi: 10.1080/00207543.2014.955218

This study introduces a new hybrid design for a specific case of assembly lines, and proposes a m... more This study introduces a new hybrid design for a specific case of assembly lines, and proposes a multi-pass random assignment algorithm to find the minimum number of stations required. The algorithm also finds the sequence and the schedule of the tasks assigned. The new design is a combination of two-sided lines and U-shaped lines, which benefits from the advantages of both designs at the same time. One side of the line is arranged in U-shape allowing stations with crossovers, and the other side of the line is balanced like a traditional straight flow. Depending on product direction, either Left or Right side of the line can be designed in U-shape. Small and large-sized two-sided assembly line test-bed problems were solved using the algorithm. Optimal results are achieved for all small-sized problems. Due to the novelty of the design, results of large sized problems are compared to findings of studies on simple two-sided balancing. Algorithm produced better results in most of the cases.

ABSTRACTIn recent years, there has been an increasing trend towards using robots in production s... more ABSTRACTIn recent years, there has been an increasing trend towards using robots in production systems. Robots are used in different areas such as packaging, transportation, loading/unloading and especially assembly lines. One important step in taking advantage of robots on the assembly line is considering them while balancing the line. On the other hand, market conditions have increased the importance of mixed-model assembly lines. Therefore, in this article, the robotic mixed-model assembly line balancing problem is studied. The aim of this study is to develop a new efficient heuristic algorithm based on beam search in order to minimize the sum of cycle times over all models. In addition, mathematical models of the problem are presented for comparison. The proposed heuristic is tested on benchmark problems and compared with the optimal solutions. The results show that the algorithm is very competitive and is a promising tool for further research.