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Öğe Allied Closed-Loop Supply Chain Network Optimization with Interactive Fuzzy Programming Approach(SPRINGER INTERNATIONAL PUBLISHING AG, 2017) Calik, Ahmet; Pehlivan, Nimet Yapici; Paksoy, Turan; Karaoglan, IsmailThe concept of closed-loop supply chain (CLSC) has started to attract growing attention due to the consumer pressures, environmental awareness, and legislations. Managers in many companies have realized that a well-designed supply chain (SC) can improve the companies' performance in the market. Thus, a lot of companies start to focus on CLSC issues including remanufacturing, refurbishing, recycling, and disposal of end-of-life products. The body of literature on CLSC management has been overwhelmingly dominated by noncooperative studies. In order to fill up this gap in the literature, we deal with an allied SC network in cooperative environment. With the implementation of allied SCs, companies not only maximize their profit but also minimize their various costs and become more flexible and efficient in the market. Following this motivation, we develop a decentralized multilevel CLSC model for allied SCs. At the first decision level, the plants in allied SCs are considered as the upper-level DMs of the Stackelberg game. At the second level, raw material suppliers, common suppliers, assembly centers, and common collection centers are considered as the lower-level DMs of the Stackelberg game. In order to tackle each decision-maker (DM)'s unique objectives, we propose a new fuzzy analytic hierarchy process (AHP)-based interactive fuzzy programming (IFP) approach. In the IFP approach, upper-level DMs determine the minimum satisfactory level for their own objectives, and by using this value, the lower DMs evaluate their own satisfactory level. A compromise solution can be derived until termination conditions are satisfied. The primary aim of this study is to design a decentralized CLSC network in cooperative environment and to propose a novel IFP approach. Finally, a numerical example is implemented and analyzed in order to demonstrate the efficiency of the proposed approach.Öğe Application of fuzzy optimization to a supply chain network design: A case study of an edible vegetable oils manufacturer(ELSEVIER SCIENCE INC, 2012) Paksoy, Turan; Pehlivan, Nimet Yapici; Ozceylan, ErenThis study applies fuzzy sets to integrate the supply chain network of an edible vegetable oils manufacturer. The proposed fuzzy multi-objective linear programming m attempts to simultaneously minimize the total transportation costs. The first part of total transportation costs is between suppliers and silos; and rest one is between manufacturer and warehouses. The approach incorporates all operating realities and actual patterns at production/distribution network with reference to demands of warehouse capacities of tin and pet packaging lines. The model has been formulated as a multi objective linear programming model where data are modeled by triangular fuzzy numb Finally, the developed fuzzy model is applied for the case study, compiled the re ! and discussed. (C) 2011 Elsevier Inc. All rights reserved.Öğe A Decentralized Model for Allied Closed-Loop Supply Chains: Comparative Analysis of Interactive Fuzzy Programming Approaches(SPRINGER HEIDELBERG, 2017) Calik, Ahmet; Paksoy, Turan; Yildizbasi, Abdullah; Pehlivan, Nimet YapiciThe supply chain network design problem addresses various factors that maximize customers' demand and minimizes the sum of strategic, tactical, and operational costs. Companies with common activities in their supply chains have started to cooperate with each other to achieve better service levels. Based on this initiative, a multi-level mixed-integer linear programming model is developed that includes two allied supply chains with different decision makers (DM) at two different decision-making levels. The primary aim of this study is to design an allied closed-loop supply chain (CLSC) network that uses some of the same facilities. The secondary aim of this study is to examine this allied CLSC model simultaneously and analyse the impact of the DMs' objectives based on satisfaction degrees. Various interactive fuzzy programming (IFP) approaches were utilized to examine the presented multi-level CLSC model. A novel IFP approach which is based on the fuzzy analytic hierarchy process (AHP) is proposed. The effectiveness of the proposed IFP approach on the CLSC model is investigated with hypothetical data. The computational results show that the proposed approach obtains higher satisfaction degrees for upper-level DMs than the other approaches.Öğe Efficacy of Frequency Doubling Technology Perimetry in Non-arteritic Anterior Ischaemic Optic Neuropathy with Altitudinal Visual Field Defects(INFORMA HEALTHCARE, 2012) Bakbak, Berker; Gedik, Sansal; Koktekir, Bengu Ekinci; Pehlivan, Nimet YapiciThe aim of the study was to evaluate the ability of frequency doubling technology perimetry to detect altitudinal hemifield defects in cases of non-arteritic anterior ischaemic optic neuropathy. Thirty eyes of 24 cases of the disorder with typical altitudinal visual field defects underwent standard automated (Humphrey 24-2) and frequency doubling technology (N-30 threshold) perimetry. For both techniques locations showing a defect of p < 5% were considered abnormal and the mean percentage defect of both the involved and uninvolved hemifields and global visual field parameters were compared. The mean percentage defects for the involved and uninvolved hemifields were comparable (p = 0.1 and p = 0.07, respectively) but there were statistically significant differences in fixation losses and in test duration (p < 0.001 and p < 0.001, respectively) for the two techniques. The authors conclude that frequency doubling technology perimetry is reliable and easily performed in patients with altitudinal visual field defects. The similarity of the extent of visual field defects found using the two techniques suggests that frequency doubling technology perimetry can be used for the rapid detection of altitudinal defects in anterior ischaemic optic neuropathy.Öğe A fuzzy linear programming model for the optimization of multi-stage supply chain networks with triangular and trapezoidal membership functions(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Paksoy, Turan; Pehlivan, Nimet YapiciSupply chain management (SCM) is concerned with a complex business relations network that contains interrelationships between various entities, such as suppliers, manufacturers, distribution centers and customers. SCM integrates these entities and manages their interrelationships through the use of information technology to meet customer expectations (i.e., higher product variety and quality, lower costs and faster responses) effectively along the entire value chain. Thus, one of the vital issues in supply chain management is the design of the value chain network. In this paper, a fuzzy linear programming model for the optimization of the multi-stage supply chain model with triangular and trapezoidal membership functions is presented. The model determines the fuzzy capacities of the facilities (plants or distribution centers (DCs)) and the design of the network configuration with a minimum total cost. The total cost involves the shipping cost from suppliers; transportation costs between plants and DCs; distribution costs between DCs and customer zones; and opportunity costs from not having the material at the right time. The developed model is solved by a professional software package (LINDO), and the computational results are discussed. (C) 2011 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.Öğe Fuzzy Programming Approach to an Environmental Supply Chain Network Design Problem(OLD CITY PUBLISHING INC, 2015) Ozceylan, Eren; Pehlivan, Nimet Yapici; Paksoy, TuranIncreasing the environmental concerns with legislations and responsibilities are forcing enterprises to take an attention at the impact of their supply chain operations on the environment. An optimally designed supply chain network is required to provide economic, social and environmental requirements in good flows actualizing between suppliers, manufacturers and customers. A nonlinear mixed integer programming model is proposed with the aimed of optimally determining consumed fuel, emitted CO2, driver and transportation costs in this study. However, real world supply chain operations are occurred in a highly dynamic and imprecise environment. Thus, a fuzzy mathematical programming approach is applied to cope with uncertainty in the capacities and demands. The proposed fuzzy model is validated and also compared with different fuzzy mathematical programming approaches through an example, where its applicability is demonstrated for managerial insights.Öğe Fuzzy radial basis function network for fuzzy regression with fuzzy input and fuzzy output(SPRINGER HEIDELBERG, 2016) Pehlivan, Nimet Yapici; Apaydin, AysenIn this study, fuzzy regression ( FR) models with fuzzy inputs and outputs are discussed. Some of the FR methods based on linear programming and fuzzy least squares in the literature are explained. Within this study, we propose a Fuzzy Radial Basis Function ( FRBF) Network to obtain the estimations for FR model in the case that inputs and outputs are symmetric/nonsymmetric triangular fuzzy numbers. Proposed FRBF Network approach is a fuzzification of the inputs, outputs and weights of traditional RBF Network and it can be used as an alternative to FR methods. The FRBF Network approach is constructed on the basis of minimizing the square of the total difference between observed and estimated outputs. A simple training algorithm from the cost function of the FRBF Network through Backpropagation algorithm is developed in this study. The advantage of our proposed approach is its simplicity and easy computation as well as its performance. To compare the performance of the proposed method with those given in the literature, three numerical examples are presented.Öğe A New Trade-off Model for Fuzzy Supply Chain Network Design and Optimization(ATLANTIS PRESS, 2011) Paksoy, Turan; Pehlivan, Nimet Yapici; Ozceylan, ErenThis problem includes fuzzy parameters, choosing suppliers according to their quality raw materials and supplier contracts. There is a trade-off between raw material quality, its purchasing and reprocessing costs. If decision maker (DM) wishes to work with a supplier which supplies a low quality raw material, this raw material can be in need of reprocessing. To avoid the reprocessing costs, a supplier which serves a high quality raw material can be chosen but at this time the DM has to face a high purchasing cost. An integrated fuzzy supply chain network system is considered to accomplish problems aforementioned trade-offs above.Öğe A New Tradeoff Model for Fuzzy Supply Chain Network Design and Optimization(TAYLOR & FRANCIS INC, 2013) Paksoy, Turan; Pehlivan, Nimet Yapici; Ozceylan, ErenThis article proposes a novel mixed integer linear programming model for solving a fuzzy supply chain network (SCN) design problem. This problem includes fuzzy parameters, choosing suppliers according to their quality of raw materials, and the supplier's engagement contracts. There is a tradeoff between raw material quality, and its purchasing and reprocessing costs. If a decision-maker (DM) wishes to work with a supplier that supplies a low-quality raw material, this raw material may be in need of reprocessing. To avoid the reprocessing costs, a supplier that provides a high-quality raw material can be chosen, but in this case the DM faces a high purchasing cost. An integrated fuzzy SCN system that consists of multiple suppliers, manufacturers, distribution centers, and retailers is considered in order to address problems under the aforementioned tradeoffs. Finally, concluding remarks and suggestions for future work are presented.Öğe A Novel Interactive Fuzzy Programming Approach for Optimization of Allied Closed-Loop Supply Chains(ATLANTIS PRESS, 2018) Calik, Ahmet; Pehlivan, Nimet Yapici; Paksoy, Turan; Weber, Gerhard WilhelmIn recent years, the relationship between companies and suppliers has changed with the continuous rise in environmental awareness and customer expectations. In order to fulfill customers' needs, the actors in a Supply Chain (SC) network sometimes compete and sometimes cooperate with each other. In SC management, both competitive and collaborative strategies have become important and have required different points of view. In a collaborative environment, companies should strive for common targets with mutual relationship. After managers decided to share their resources, some positive effects have appeared on the companies and suppliers' performance such as profitability, flexibility and efficiency. Consequently, many companies are willing to cooperate with each other in a SC network because of these reasons. On the other hand, Closed-Loop Supply Chain (CLSC) management has been attracting a growing interest because of increased environmental issues, government regulations and customer pressures. Based on this initiative, our paper presents a novel allied CLSC network design model with two different SCs including common suppliers and common collection centers. First, a decentralized multi-level Mixed-Integer Linear Programming (MILP) model that consists of two different levels of Decision Makers (DMs) is developed. The plants of common SCs comprise the upper-level DMs, common suppliers, common collection centers, and the logistics firm comprises the lower-level DMs. A novel Interactive Fuzzy Programming (IFP) approach using Fuzzy Analytic Hierarchy Process (AHP) is proposed to obtain a preferred compromise solution for the developed model. Through use of Fuzzy AHP in the proposed IFP approach, the DMs can identify the importance of the lower-level DMs. In order to validate the developed model and the proposed IFP approach, a numerical example is implemented. According to the obtained results, our proposed IFP method outperforms Sakawa and Nishizaki's(1) and Calik et al.' s(2) approach with respect to the satisfaction degrees of upper-level DMs for the developed CLSC model.
