Endüstri Mühendisliği Bölümü Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/226

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    Citation Count: ELKER, S. (2008). A manufacturing system analysis combined with waste management. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    A manufacturing system analysis combined with waste management
    (2008-07-18) Elker, Sedef; Çankaya Üniversitesi, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü
    This thesis presents an environmentally integrated manufacturing system analysis for companies looking for the benefits of environmental management in achieving high efficiency levels. When the relationship between environmental costs and manufacturing decisions is examined, it can be seen that the productivity of the company can be increased by using an environmentally integrated manufacturing system analysis methodology. Therefore, such a methodology is proposed and the roadmap for generating environmentally friendly and economically favorable alternative waste management solutions is elaborated. The methodology consists of data collection, operational analyses of the processes, identification of wastes and evaluation of waste reduction alternatives proposed both technically and economically. The proposed methodology is examined in a car battery manufacturing company, which generates hazardous wastes composed of lead (Pb). The main focus was on the wet-charged lead-acid battery manufacturing. It is aimed to decrease the wastes derived from the production so that the efficiency in raw materials usage is increased and the need for recycling the hazardous wastes is decreased. Following the identification of waste production points, at least one alternative is proposed for the reduction of waste. Two different alternatives are proposed for the reduction of dross formation based on the results obtained from the experiments carried out. The applicability of alternative waste management solutions is investigated from operational, technical and economical point of views and benefits and limitations are identified for each of the alternatives.
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    Citation Count: AKBULUT, D. (2012). An edge matching approach for two-dimensional irregular shaped cutting stock problems. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    An edge matching approach for two-dimensional irregular shaped cutting stock problems
    (2012-08-27) Akbulut, Derya; Çankaya Üniversitesi, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü
    In this thesis, a two-dimensional irregular shape cutting stock problem is considered, in which a number of irregular shaped pieces are cut out of rectangular stock sheets so that waste of stock to be minimized. This is an operational problem commonly observed in metal cutting and textile industries. In the literature, there are many algorithms proposed to find optimal or suboptimal solutions for the problem. Since the problem is NP-hard, heuristic approaches predominate among the solution methodologies. In this study, a non-linear mixed integer mathematical model formulation is developed and it is tested for small sized problems. For larger scale problems, an edge matching approach is proposed to generate cutting patterns. The approach is based on positioning of the pieces in such a way that their most fitting edges are aligned together or to the borders. In this way, the total scrap and the cutting operations are minimized. On the contrary to the most of the solution methodologies in the literature, the method enables rotating pieces by any angle during the alignment process and further more it is applicable for irregular shaped stock materials. The developed procedure is tested against the traditional cutting stock approaches using benchmark test problems reported in the literature. It is found that our procedure outperforms for a large portion of these benchmark problems.
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    Citation Count: KESKİN, M. (2013). Freight transportation in Turkish state railways (tcdd) high-speed train system. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    Freight transportation in Turkish state railways (tcdd) high-speed train system
    (2013-03-11) Keskin, Merve; Çankaya Üniversitesi, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü
    The aim of this thesis is to improve the freight transportation system of Turkish State Railways (TCDD) by using high speed trains (HSTs) on high speed lines as a new concept. The development of railway and HST systems in the world and in Turkey is discussed and comparison of these systems with other transportation modes is investigated. Since HST is faster than trucks and cheaper than airlines for freight transportation and increases the utilization of railway system substantially, it is very advantageous. While HSTs are used for freight transportation in some countries such as France, Germany etc., they are not used currently for freight transportation in Turkey. Therefore, in this thesis, freight is added to the existing high speed rail system which is currently used for only passengers. A HST scheduling model is constructed to observe the effects of freight when it is included in the system. The aim of the model is to complete daily travel as early as possible within a day to increase utilization of the system. Daily travel of each train consists of sequence of cities and links between these cities. In experimental study, two types of sequence of cities are used: trips using one sequence of cities and trips using two sequences of cities. In the first type, all available trains are used to perform daily travels in one sequence of cities. Then for the second type, the linkage is divided into two and available trains are allocated to these separate two linkages. Freight transportation is also analyzed in two cases which are adding separate freight trains to the system and using the same trains with passengers for freight transportation. It can be concluded that dividing the sequence of cities into two provides the completion of the train services earlier in a day and using the same trains with passengers for freight transportation provides more time savings for the system. Freight transportation in HSTs is a complex task to achieve and requires many factors to be taken into account. This thesis is a first attempt to address this complex task.
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    Citation Count: KILIÇ, T. (2009). Fuzzy regression modeling of rates in a metal casting process. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    Fuzzy regression modeling of rates in a metal casting process
    (2009-10-23) Kılıç, Tuna; Çankaya Üniversitesi, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü
    This study has two purposes. One of them is to develop model of a metal casting process quality. This model can be used by the company to reduce the number of defects by identifying the process variables which have the most important effects on a certain defect type. The second purpose is to test and develop certain fuzzy regression approaches for the case problem. In the case study, 36 process variables are observed from the metal casting process. Initially, stepwise linear regression (LR) method is applied to the data set and 8 independent variables are selected as significant. When the process variables are examined, it is realized that instead of identifying them as crisp, expressing them with fuzzy numbers is more appropriate. In the scope of the study, all fuzzy numbers are assumed to be triangular fuzzy numbers. First the Hojati-Bector-Smimous (HBS2) method developed by Hojati et al. (2005) is generalized to multi variable modeling and then applied to the data set. In order to make a comparison between HBS2 and linear regression (LR) approach, the latter is also applied. Similarly, in order to make a comparison between HBS2 and other fuzzy methods, Fuzzy Functions (FF) method developed by Türkşen and Çelikyılmaz (2006) is used. Furthermore, Non-Parametric Improved Fuzzy Classification Functions developed by Özer (2009) is adapted to the case of fuzzy linear regression. The newly developed method called as Non-Parametric Improved Fuzzy Functions (NIFF) is applied to the same data set for a comparison with the other solutions.
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    Citation Count: SOYSAL, S. (2008). Scheduling in a three-stage dedicated hybrid flowshop with a common third-stage. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    Scheduling in a three-stage dedicated hybrid flowshop with a common third-stage
    (2008-09-12) Soysal, Serdar; Çankaya Üniversitesi, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü
    In this study, we consider a scheduling problem of a manufacturing environment in which there are two manufacturing flow lines, where the third stage of the first line and the second stage of the second line are common. Each stage in the first flow line has a single machine whereas the second flow line contains two identical parallel machines in its first stage. Type-1 jobs are processed in the first flow line, whereas second flow line is dedicated to type-2 jobs. The last operation, of both types of jobs, must be processed on a common machine. The problem is to determine the sequence and schedule of all jobs at all stages of the two flow lines so that the makespan is minimized. We develop a mathematical model and a branch-and-bound algorithm with lower and upper bounding procedures to find optimal solution; we propose heuristic algorithms which provide good quality solutions at little computational effort when the computational effort to obtain an exact solution is prohibitive. The effectiveness of our solution approaches are demonstrated by computational analyses.
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    Citation Count: ÖZEN, D. (2013). Spare parts inventory management with demand priorities. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    Spare parts inventory management with demand priorities
    (2013-02-06) Özen, Duygu; Çankaya Üniversitesi, Fen Bilimleri Enstitüsü, Endüstri Mühendisliği Bölümü
    In this thesis, we analyze a single-echelon inventory management problem of a manufacturing company which is a subsidiary company of an engineering company. The company manufactures machines and also supplies supplementary equipment and spare parts to its customers. Based on the priorities in meeting the demands, the customers of the manufacturing company are classified as high priority and low priority customers. The engineering company which is the most important customer is treated as the high priority customer whereas all other customers having the same priority are assumed to be the low priority customers. In this study, considering these two types of customers, we focus on an (R, Q) inventory model with a critical level policy where backorders and lost sales are allowed. Below the critical level the demands of low priority customers are not met to retain stock for high priority customer and therefore the unmet demands of low priority customers are lost. The demands of high priority customer are satisfied until inventory level reaches zero and under stock out any unsatisfied demand of high priority customer is backordered. Considering the possible levels of reorder point (R) and critical point (c), three different cases are defined as c=R, c>R, and c
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    Citation Count: KARABAK, F. (2012). Workforce assignment in a multi-worker multi-sided mixed-model assembly line balancing problem. Yayımlanmamış yüksek lisans tezi. Ankara: Çankaya Üniversitesi Fen Bilimleri Enstitüsü
    Workforce assignment in a multi-worker multi-sided mixed-model assembly line balancing problem
    (2012-09) Karabak, Funda; Çankaya Üniversitesi, Mühendislik Fakültesi, Endüstri Mühendisliği Bölümü
    In this thesis, workforce scheduling problem in a mixed model assembly line is studied in which precedence relations, qualification of workers, walking times between tasks and worker requirements are considered. The motivation of the study comes from a real life problem at MAN Türkiye A.Ş. Mixed integer linear programming formulations for minimization of number of actively used workers and minimization of makespan value are developed. However, since the problem is NP-Hard, a heuristic approach is introduced. The developed heuristic attempts to minimize the number of actively used workers first, and then to minimize the makespan value.