Browsing by Author "Ayağ, Zeki"

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Citation Count: 0
AHP-BASED APPROACH TO EVALUATE SOLAR POWER PLANT LOCATION ALTERNATIVES
(Intl Inst Social & Economic Sci, 2016) Ayağ, Zeki
Solar energy is the most readily available source of energy, and one of the most important sources of the renewable energy, because it is non-polluting and helps in lessening the greenhouse effect. Main problem of establishing a solar power plant is to determine its location. In the presence of many location alternatives and evaluation criteria, a multiple-criteria decision making problem arises. In this work, the location problem will be solved by using analytic hierarchy process (AHP) to figure out the most satisfying alternative. A numerical example is also included to show the proposed methodology in Turkey. . . . .
Citation Count: 3
Analytic Network Process (ANP) for solar power plant location problem
(Institute of Industrial Engineers, 2010) Samanlıoğlu, Funda; Ayağ, Zeki
Solar energy is the most readily available source of energy and one of the most important sources of the renewable energy because it is non-polluting and helps in lessening the greenhouse effect. Main problem of establishing a solar power plant is to determine its location. In the presence of many location alternatives and evaluation criteria a multiple-criteria decision making problem arises. In this work the location problem will be solved by using Analytic Network Process (ANP) to figure out the most satisfying alternative. A numerical example is also included to show the proposed methodology in Turkey.
Citation Count: 87
An analytic network process-based approach to concept evaluation in a new product development environment
(Taylor & Francis, 2007) Ayağ, Zeki; Özdemir, Rifat Gürcan
Selecting the best product concept is one of the most critical tasks in a new product development (NPD) environment. Making decisions at this stage becomes very difficult due to imprecise and uncertain product requirements. So the evaluation process of determining the most satisfying conceptual design has been a very vital issue for companies to survive in fast-growing markets for a long time. Therefore most companies have used various methods to successfully carry out this difficult and time-consuming process. Of these methods an analytic hierarchy process (AHP) has been widely used in multiple-criteria decision-making problems (i.e. concept selection equipment evaluation). In this study however we use an analytic network process (ANP) a more general form of AHP due to the fact that AHP cannot accommodate the variety of interactions dependencies and feedback between higher and lower level elements. Briefly in this paper an ANP-based approach is presented to evaluate a set of conceptual design alternatives in order to reach to the best concept satisfying the needs and expectations of both customers and company. In addition a numerical example is presented to illustrate the proposed approach.
Citation Count: 1
An approach to evaluate CAM software alternatives
(TAYLOR & FRANCIS LTD, 2020) Ayağ, Zeki
The selection process for the best computer-aided manufacturing (CAM) software among a set of potential number of alternatives in market has been critical issue for most companies that aim to make their design/manufacturing-related activities automated. Because this selection process is very vital for companies because a wrong decision might put them into a difficult position in terms of economical, market share and time spent. Therefore, today's companies have used different multiple-criteria decision making (MCDM) methods for the evaluation study of CAM software alternatives to make this complex process easily applicable and not time-consuming. Among the MCDM methods in literature, the analytic hierarchy process (AHP) method has been widely used for various MCDM problems in both academic researches and industrial practices. However, in some cases, because of the vagueness and uncertainty on the judgments of decision maker(s), the crisp pair wise comparison in the conventional AHP seems to be insufficient and imprecise to capture the right judgments of decision maker(s). Therefore, a fuzzy logic method is integrated in the pair wise comparison of AHP to make up for this deficiency in the conventional AHP, called as fuzzy AHP. Moreover, the proposed approach is also realized on a case study.
Citation Count: 2
Cad software evaluation for product design to exchange data in a supply chain network
(ExcelingTech Publishers, 2015) Ayağ, Zeki
The sharing information in a supply chain environment especially CAD models and drawings are so important companies. So the selection of the most satisfying computer-aided design (CAD) software which enables to exchange data through supply chain network has been major issues for companies in a supply chain. The selection process of CAD software among the raising number of alternatives in the market has been very vital and critical issue for companies that aim to make their design and engineering related activities automated towards computer integrated manufacturing (CIM) environment. Therefore most companies have used various methods to successfully carry out this difficult and time-consuming process. Of these methods Analytic Hierarchy Process (AHP) has been widely used for Multiple Criteria Decision Making (MCDM) problems in both academic researches and practices. But in some cases due to the vagueness and uncertainty on judgments of the decisionmaker(s) the crisp pair wise comparison in the conventional AHP seems to be insufficient and imprecise to capture the right judgments of decision-maker(s). Therefore a fuzzy logic is introduced in the pair wise comparison of AHP to make up for this deficiency in the conventional AHP called as fuzzy AHP. In this paper a fuzzy AHP-based approach is proposed to evaluate a set of CAD software alternatives in the market to reach the best satisfying one based on the needs of company. © ExcelingTech Pub UK.
Citation Count: 12
A combined fuzzy AHP-goal programming approach to assembly-line selection
(IOS Press, 2007) Ayağ, Zeki; Özdemir, Rıfat Gürcan
In mass production assembly-line balancing (ALB) problem has been a critical and repetitive issue for companies for long time. On the other hand equipment selection for stations has also been another important problem at the design stage of an assembly-line system. In this paper both problems are handled simultaneously. Therefore first goal programming (GP) method a well-suited technique is used to develop a preemptive formulation to joint both of the problems when the nature of the problem consists of several conflicting objectives and some mathematical constraints on solutions. Second an AHP method based on fuzzy scales which is incorporated with the GP is also used due to the fact that it takes both qualitative and quantitative judgments of decision-maker(s) into consideration to rank the equipment alternatives for stations by weight. The fuzzy AHP as one of the most commonly used multiple-criteria decision making (MCDM) methods has been effectively used for more than decade in both academic research and practice and takes the vagueness and uncertainty on judgments of decision-maker(s) into consideration due to the fact that the crisp pairwise comparison in the conventional AHP seems to insufficient and imprecise to capture the right judgments of decision-maker(s). In short in this study a combined fuzzy AHP-GP approach is proposed to evaluating assembly-line design alternatives with equipment selection. An integer GP formulation is constructed which also uses the fuzzy AHP scores of equipment alternatives and employs them as one of the goals. Then the mathematical model is solved to find out the ultimate alternative in terms of the minimized equipment cost and the maximized preference measures of decision-maker(s). The proposed approach is also illustrated on a sample case study.
Citation Count: 15
A combined fuzzy AHP-simulation approach to CAD software selection
(Taylor & Francis Ltd, 2010) Ayağ, Zeki
In this paper a combined approach where the fuzzy analytic hierarchy process (AHP) and simulation come together is presented to select the best computer-aided design (CAD) software out of the available options in the market. The fuzzy AHP is used due to the vagueness and uncertainty of the judgements of a decision maker(s) because the crisp pair-wise comparison in the conventional AHP seems to be insufficient and imprecise to capture the right judgements of the decision maker(s). In this study first the fuzzy AHP is used to reduce a possible number of alternatives for the CAD system to an acceptable level for further study simulation analysis. Secondly a simulation generator as an integrated part of the fuzzy AHP is used to try the remaining alternatives on the generated model of a real-life product organisation in which the final alternative will be used. The results of simulation experiments are obtained and then evaluated to reach to the ultimate CAD alternative.
Citation Count: 11
A comparison study of fuzzy-based multiple-criteria decision-making methods to evaluating green concept alternatives in a new product development environment
(EMERALD GROUP PUBLISHING LTD, 2021) Ayağ, Zeki
Purpose In this paper, the four popular multiple-criteria decision-making (MCDM) methods in fuzzy environment are utilized to reflect the vagueness and uncertainty on the judgments of decision-makers (DMs), because the crisp pairwise comparison in these conventional MCDM methods seems to be insufficient and imprecise to capture the right judgments of DMs. Of these methods, as Fuzzy analytic hierarchy process (F-AHP) is used to calculate criteria weights, the other methods; Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (F-TOPSIS), Fuzzy Grey relational analysis (F-GRA) and Fuzzy Preference Ranking Organization METhod for Enrichment of Evaluations (F- PROMETHEE II) are used to rank alternatives in the three different ways for a comparative study. Design/methodology/approach The demand for green products has dramatically increased because the importance and public awareness of the preservation of natural environment was taken into consideration much more in the last two decades. As a result of this, especially manufacturing companies have been forced to design more green products, resulting in a problem of how they incorporate environmental issues into their design and evaluate concept options. The need for the practical decision-making tools to address this problem is rapidly evolving since the problem turns into an MCDM problem in the presence of a set of green concept alternatives and criteria. Findings The incorporation of fuzzy set theory into these methods is discussed on a real-life case study, and a comparative analysis is done by using its numerical results in which the three fuzzy-based methods reveal the same outcomes (or rankings), while F-GRA requires less computational steps. Moreover, more detailed analyses on the numerical results of the case study are completed on the normalization methods, distance metrics, aggregation functions, defuzzification methods and other issues. Research limitations/implications The designing and manufacturing environmental-friendly products in a product design process has been a vital issue for many companies which take care of reflecting environmental issues into their product design and meeting standards of recent green guidelines. These companies have utilized these guidelines by following special procedures at the design phase. Along the design process consisting of various steps, the environmental issues have been considered an important factor in the end-of-life of products since it can reduce the impact on the nature. In the stage of developing a new product with the aim of environmental-friendly design, the green thinking should be incorporated as early as possible in the process. Practical implications The case study was inspired from the previous work of the author, which was realized in a hot runner systems manufacturer, used in injection molding systems in a Canada. In a new product development process, the back- and front-ends of development efforts mainly determine the following criteria: cost, risk, quality and green used in this paper. The case study showed that the three fuzzy MCDM methods come to the same ranking outcomes. F-GRA has a better time complexity compared to the other two methods and uses a smaller number of computational steps. Moreover, a comparative analysis of the three F-MCDM methods; F-PROMETHEE II, F-TOPSIS and F-GRA used in ranking for green concept alternatives using the numerical results of the case study. For the case study; as seen in table 20, the three F-MCDM methods produced the numerical results on the rankings of the green concept alternatives as follows; {Concept A-Concept C-Concept B-Concept D}. Social implications Inclusion of environmental-related criteria into concept selection problem has been gaining increasing importance in the last decade. Therefore, to facilitate necessary calculations in applying each method especially with its fuzzy extension, it can be developed a knowledge-based (KB) or an expert system (ES) to help the DMs make the required calculations of each method, and interpret its results with detailed analysis. Originality/value The objective of the research was to propose a F-AHP based F-MCDM approach to green concept selection problem through F-PROMETHEE II, F-TOPSIS and F-GRA methods. As the F-AHP is used to weight evaluation criteria, the other methods are respectively used for ranking the concept alternatives and determine the best concept alternative.
Citation Count: 3
Determining master schedule of surgical operations by integer programming: A case study
(Institute of Industrial Engineers, 2010) Samanlıoğlu, Funda; Ayağ, Zeki; Batili, Burcin; Evcimen, Esra; Yılmaz, Gulsah; Atalay, Ozlem
Fixed amounts of available Operating Room (OR) time compatibility of ORs and restrictions related to surgery equipment and surgeon availabilities complicate the process of preparing the master surgical schedule at hospitals. In this research an integer programming model and its application at Etiler World Eye Hospital (in Turkey) are presented in order to create a master surgical schedule that includes the most common surgery types on weekly basis and resolves surgeon equipment and operating room restriction and availability issues. The integer programming model utilizes the available OR time at the hospital by minimizing the total underallocation of OR time with respect to targeted OR time of surgeons taking into consideration surgeon equipment and OR restrictions and availabilities. The mathematical model is then solved using a commercial solver to obtain a weekly master surgical schedule for the hospital.
Citation Count: 65
Evaluating machine tool alternatives through modified TOPSIS and alpha-cut based fuzzy ANP
(Elsevier Science Bv, 2012) Ayağ, Zeki; Özdemir, Rıfat Gürcan
The problem of machine tool selection among available alternatives has been critical issue for most companies in fast-growing markets for a long time. In the presence of many alternatives and selection criteria the problem becomes a multiple-criteria decision making (MCDM) machine tool selection problem. Therefore most companies have utilized various methods to successfully carry out this difficult and time-consuming process. In this work both of the most used MCDM methods the modified TOPSIS and the Analytical Network Process (ANP) are introduced to present a performance analysis on machine tool selection problem. The ANP method is used to determine the relative weights of a set of the evaluation criteria as the modified TOPSIS method is utilized to rank competing machine tool alternatives in terms of their overall performance. Furthermore in this paper we use a fuzzy extension of ANP a more general form of AHP which uses uncertain human preferences as input information in the decision-making process because AHP cannot accommodate the variety of interactions dependencies and feedback between higher and lower level elements. Instead of using the classical eigenvector prioritization method in AHP only employed in the prioritization stage of ANP a fuzzy logic method providing more accuracy on judgments is applied. The resulting fuzzy ANP enhances the potential of the conventional ANP for dealing with imprecise and uncertain human comparison judgments. The proposed approach is also applied for a real-life case in a company. (C) 2012 Elsevier B.V. All rights reserved.
A fuzzy AHP approach for financial performance evaluation airline companies
(Kadir Has Üniversitesi, 2012) Ayağ, Zeki; Ayağ, Zeki
Previous researches focused on operation performance. This thesis purposes for evaluating the financial performance of the airlines. In order to achieve financial objectives to be incorporated into the financial performance of their degree. It is a method to measure the results of a company?s operations in a monetary term. The problem is modeled by multi-criteria decision making (MCDM) one. Multi criteria decision making (MCDM) is a method of the most important fields of operations research and deals with the problems that include multiple and conflicting objectives. It is obvious that when more than objective exists in the problem, making a decision becomes more complex. To solve the problem, I used the fuzzy numbers to explain their values. After that, I used a method of fuzzy multi criteria group decision making (FMCGDM) as Fuzzy Analytic Hierarchy Process (FAHP) to solve the problem of the evaluation of airlines? financial performances. At first time the decision making process of the financial performance is investigated, when financial ratios are given by a fuzzy function, they are obtained through classical methods. After that, we will discuss the main advantages of the new approach. Finally, we illustrate an experimantal model of evaluation of the three domestic airlines? financial performance in Turkey.
Citation Count: 224
A fuzzy AHP approach to evaluating machine tool alternatives
(Springer, 2006) Ayağ, Zeki; Özdemir, Rifat Gürcan
Selecting process of a machine tool has been very important issue for companies for years because the improper selection of a machine tool might cause of many problems affecting negatively on productivity precision flexibility and company's responsive manufacturing capabilities. On the other hand selecting the best machine tool from its increasing number of existing alternatives in market are multiple-criteria decision making (MCDM) problem in the presence of many quantitative and qualitative attributes. Therefore in this paper an analytic hierarchy process (AHP) is used for machine tool selection problem due to the fact that it has been widely used in evaluating various kinds of MCDM problems in both academic researches and practices. However due to the vagueness and uncertainty on judgments of the decision-maker(s) the crisp pair wise comparison in the conventional AHP seems to insufficient and imprecise to capture the right judgments of decision-maker(s). That is why
Citation Count: 17
Fuzzy AHP-GRA approach to evaluating energy sources: a case of Turkey
(EMERALD GROUP PUBLISHING LTD, 2020) Samanlıoğlu, Funda; Ayağ, Zeki
Purpose Since the demand for energy has dramatically increased in the countries which have fast-growing population and economy, they have faced with a critical problem of how to evaluate a set of potential energy sources (i.e. nuclear, natural gas, bio, geothermal, hydro, wind and solar) and choose the ultimate energy source for their needs. On the other hand, this critical problem turns into a multiple-criteria decision-making (MCDM) in the presence of a set of energy source alternatives and evaluation criteria. In literature, there are many MCDM methods introduced to solve for different kinds of problems. The purpose of this paper is to present an integrated approach for evaluating energy sources using fuzzy AHP and GRA, with a case for Turkey. Design/methodology/approach In this paper, the analytic hierarchy process (AHP) and grey relational analysis (GRA) methods are used because of their advantages for similar problems. On the other hand, due to the fact that the conventional AHP by a nine-point scale and GRA method using a scale with crisp values can be unable to handle to capture the right judgments of a decision-maker(s), to reflect the vagueness and uncertainty on the judgments of a decision-maker, the fuzzy logic is integrated with the AHP and GRA. Findings The contributions of the paper to the literature are given in two dimensions as follows: it presents an integrated approach for complex decision processes with subjective data or vague information; the proposed approach, the fuzzy AHP-GRA method for energy source selection, is unique for the related problem in literature. The results of the proposed model from the case of Turkey will help practitioners and experts of how to apply it to the similar problems in the field of energy management. Social implications On the other hand, the proposed approach, the fuzzy AHP-GRA for energy source selection can also be an intelligent tool for public and private energy companies in Turkey, as well as others in the world. Originality/value On the other hand, in this paper, to the best of the authors' knowledge, the study contributes to the literature that the first time, they use the fuzzy alpha-cut AHP and GRA in fuzzy environment for energy source evaluation problem.
Citation Count: 47
A fuzzy AHP-PROMETHEE II approach for evaluation of solar power plant location alternatives in Turkey
(IOS Press, 2017) Samanlıoğlu, Funda; Ayağ, Zeki
Solar energy produced through a solar power plant is a freely available non-polluting renewable source of energy that reduces the greenhouse effect. Selecting the best location for a solar power plant among several location alternatives is a complicated multiple criteria decision making (MCDM) problem since several potentially conflicting quantitative and qualitative criteria needs to be taken into consideration. In this paper of the most commonly used MCDM methods in literature
Citation Count: 11
A fuzzy AHP-VIKOR approach for evaluation of educational use simulation software packages
(IOS Press, 2019) Samanlıoğlu, Funda; Ayağ, Zeki
In this study, an intelligent, integrated approach is presented to help educators select the best simulation software package. Selecting the best simulation software package for educational use is a complex multiple criteria decision making (MCDM) problem with several potentially conflicting quantitative and qualitative criteria. In this paper, two fuzzy MCDM methods; fuzzy Analytic Hierarchy Process (F-AHP) and fuzzy VIsekriterijumska optimizacija i KOmpromisno Resenje (F-VIKOR) are integrated to evaluate educational use simulation software package alternatives. In the proposed fuzzy AHP-VIKOR approach, F-AHP is used to determine the fuzzy criteria weights and F-VIKOR is applied to rank simulation software package alternatives with respect to these criteria. A case study is given where several educational use simulation software packages in Turkey are evaluated and ranked.
Citation Count: 3
A Fuzzy ANP Approach To Evaluate Computer Simulation Packages
(Inderscience Enterprises Ltd., 2016) Ayağ, Zeki
In this study an intelligent approach is presented to help any simulation practitioner to evaluate simulation software alternatives and determine the best satisfying one based on his/her needs. On the other hand this evaluation process is a typical multiple criteria decision making (MCDM) problem in the presence of evaluation criteria and a set of possible alternatives and there are many methods in the literature which have been used to successfully carry out this difficult and time-consuming process. In this paper one of these methods the analytic network process (ANP) method integrated with alpha-cut fuzzy logic is used because it can accommodate the variety of interactions dependencies and feedback between higher and lower level elements rather than analytic hierarchy process (AHP). In addition an alpha-cut fuzzy extension of ANP uses uncertain human preferences as input information in the decision-making process. Instead of using the classical eigenvector prioritisation method in AHP only employed in the prioritisation stage of ANP an alpha-cut fuzzy logic method providing more accuracy on judgements is applied. The resulting alpha-cut fuzzy ANP enhances the potential of the conventional ANP for dealing with imprecise and uncertain human comparison judgements. © Copyright 2016 Inderscience Enterprises Ltd.
Citation Count: 10
A fuzzy ANP-based GRA approach to evaluate ERP packages
(IGI Global, 2019) Ayağ, Zeki; Yücekaya, Ahmet
One of the major problems that most companies face with during the implementation of an ERP system is to determine the best satisfying ERP software based on their needs and expectations. Because an improperly selected ERP software might lead to time loss and increased costs and in the long run a loss of market share. Therefore the ERP evaluation process for companies becomes to a vital point. On the other hand evaluating ERP software alternatives under a set of criteria leads us to a multiple-criteria decision making (MCDM) problem and needs to use proper MCDM methods. In the current literature a number of the MCDM methods have been proposed to solve these kinds of problems both of which are the analytic network process (ANP) of Saaty and grey relational analysis (GRA) which has been widely used in solving MCDM selection problems in various fields. Moreover in this article the authors used the fuzzy extension of the ANP method to reflect the uncertainty and ambiguity of decision maker(s) into problem in order to reach more reliable solution. As the fuzzy ANP method was used to calculate the priority weights of the evaluation criteria the GRA method with fuzzy interval-values was employed to rank a set of the possible ERP software alternatives. The proposed approach was also validated in a case study to show its applicability to potential readers and practitioners. Copyright © 2019 IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited.
Citation Count: 17
Fuzzy ANP-Based PROMETHEE II Approach for Evaluation of Machine Tool Alternatives
(IOS Press, 2016) Samanlıoğlu, Funda; Ayağ, Zeki
Machine tool selection process has been a critical issue for companies for years since improper selection of a machine tool might cause many problems affecting negatively the productivity precision flexibility and company's responsive manufacturing capabilities. On the other hand selecting the best machine tool from its increasing number of existing alternatives in the market is a multiple-criteria decision making (MCDM) problem in the presence of many quantitative and qualitative attributes. Therefore most companies have utilized various methods to successfully carry out this difficult and time-consuming process. In this paper both of the most used MCDM methods
Citation Count: 42
A fuzzy QFD approach to determine supply chain management strategies in the dairy industry
(Springer, 2013) Samanlıoğlu, Funda; Ayağ, Zeki; Büyükozkan, Gülçin
The aim of this study is to identify the crucial logistics requirements and supply chain management (SCM) strategies for the dairy industry. For product or service development quality function deployment (QFD) is a useful approach to maximize customer satisfaction. The determination of design requirements and supply chain management strategies are important issues during QFD processes for product or service design. For this reason a fuzzy QFD methodology is proposed in this study to determine these aspects and to improve customer satisfaction. Qualitative information is converted firstly into quantitative parameters and then this data is combined with other quantitative data to parameterize two multi-objective mathematical programming models. In the first model the most important logistic requirements for the company are determined based on total technical importance total cost total feasibility and total value increment objectives and in the second model based on these objectives appropriate supply chain management strategies are determined. Finally a case study from the Turkish dairy industry is given to illustrate the proposed approach.
Citation Count: 20
A hesitant fuzzy linguistic terms set-based AHP-TOPSIS approach to evaluate ERP software packages
(Emerald Group Publishing Ltd, 2020) Samanlıoğlu, Funda; Ayağ, Zeki
Purpose In this paper, two popular multiple-criteria decision-making (MCDM) methods with hesitant fuzzy logic approach; hesitant fuzzy analytic hierarchy process (hesitant F-AHP) and hesitant fuzzy the technique for order preference by similarity to ideal solution (HF-TOPSIS) are integrated as HF-AHP-TOPSIS to evaluating a set of enterprise resource planning (ERP) alternatives and rank them by weight to reach to the ultimate one that satisfies the needs and expectations of a company. Design/methodology/approach Selecting the best ERP software package among the rising number of the options in market has been a critical problem for most companies for a long time because of the reason that an improper ERP software package might lead to many issues (i.e. time loss, increased costs and a loss of market share). On the other hand, finding the best ERP alternative is a comprehensive MCDM problem in the presence of a set of alternatives and several potentially competing quantitative and qualitative criteria. Findings In this integrated approach, the hesitant F-AHP is used to determine the criteria weights, as the hesitant F-TOPSIS is utilized to rank ERP package alternatives. The proposed approach was also validated in a numerical example that has five ERP package alternatives and 12 criteria by three decision-makers in order to show its applicability to potential readers and practitioners. Research limitations/implications If the number of the alternatives and criteria are dramatically increased beyond reasonable numbers, the reaching to final solution will be so difficult because of the great deal of fuzzy based calculations. Therefore, the number of criteria and alternatives should be at reasonable numbers. Practical implications The proposed approach was also validated in a illustrated example with the five ERP package options and 12 criteria by the three decision-makers in order to show its applicability to potential readers and practitioners. Originality/value Furthermore, in literature, to the best of our knowledge, the authors did not come cross any work that integrates the HF-AHP with the HF-TOPSIS for ERP software package selection problem.