Yazar "Kahraman, Cengiz" seçeneğine göre listele

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    Engineering economic analysis of solar energy investments using spherical fuzzy sets
    (World Scientific Publ Co Pte Ltd, 2020) Onar, Sezi Cevik; Oztaysi, Bazar; Kahraman, Cengiz; Otay, Irem
    Solar energy is a reliable energy source that is important for the environmental sustainability. Solar energy investments become crucial for the countries like Turkey that does not have natural fossil based fuels but has a great potential of solar energy. In order to give better solar energy investment decisions, the uncertainties and ambiguities inherit in the investment decisions should be considered. Spherical fuzzy sets enable us to deal with uncertainty and ambiguity. The membership, non-membership and the hesitancies are considered in Spherical fuzzy sets, In this study a Spherical fuzzy set based net present worth analysis is proposed to deal with uncertain solar energy investments. The applicability of the proposed model is shown by an application. In this application, a solar power plant investment is evaluated by using the proposed model.
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    Indoor location tracking technology evaluation by using spherial fuzzy TOPSIS method
    (World Scientific Publ Co Pte Ltd, 2020) Oztaysi, Basar; Kahraman, Cengiz; Onar, Sezi Cevik; Otay, Irem
    With the emerging technologies, collecting and processing data about the behaviors of customers or employees in a specific location has become possible. The purpose of this paper is to evaluate existing data collection technologies. Technology evaluation problem is handled as a multi-criteria decision-making (MCDM) problem. In this manner, a decision model containing four criteria and four alternatives are formed. In this study, we use Spherical Fuzzy TOPSIS method to solve the technology selection problem.
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    Industry 4.0 project prioritization by using spherical fuzzy analytic hierarchy process
    (World Scientific Publ Co Pte Ltd, 2020) Oztaysi, Basar; Onar, Sezi Cevik; Kahraman, Cengiz; Otay, Irem
    Industry 4.0, indicated as the Fourth Industrial Revolution, also pointed out as integrated industry, smart manufacturing and industrial internet of things, has taken a great attention in terms of the potential to reflect entire industries' actions by transforming the production to a fully automated and self-coordinated digital system. This transformation process necessitates the significant amount of investments and resources to be additionally, adaptation to the current operational technologies to new initiatives could be problematic. In this study we focus on Industry 4.0 project prioritization by using Spherical Fuzzy Analytic Hierarchy Process. In the application part, we prioritize five projects according to four main project selection criteria.
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    An Integrated Interval-Valued Picture Fuzzy CRITIC & TOPSIS Methodology: An Application to Disaster Debris Management
    (Old City Publishing Inc, 2023) Oztaysi, Basar; Onar, Sezi Cevik; Otay, Irem; Kahraman, Cengiz
    Picture fuzzy (PF) sets show the expert's opinion about an element's membership or non-membership in the set, as well as the expert's indecision about the element's membership in the set. Interval-valued PF sets (IVPFSs) offer more flexibility than single-valued PF sets in assigning the mentioned degrees. Picture fuzzy multi-criteria decision making methods or methodologies are superior to other methods or methodologies since they can take these opinions of the experts into account in the decision mechanism. CRITIC method is a criteria weighting method based on statistical terms such as correlation coefficients and standard deviations, which has become popular recently. In this paper, the PFCRITIC method will be used to calculate the weights of the criteria and the PF-TOPSIS method is used to rank the alternatives. The proposed multi-experts IVPF CRITIC&TOPSIS methodology is applied to the post-disaster location selection of debris waste sites in Istanbul. In the comparison analysis, the integrated methodology is compared with crisp TOPSIS method based on the same data. The results show that the integrated methodology gives a consistent ranking with slight differences in closeness coefficients.
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    A literature review on the extensions of intuitionistic fuzzy sets
    (World Scientific Publ Co Pte Ltd, 2020) Kahraman, Cengiz; Oztaysi, Basar; Onar, Sezi Cevik; Otay, Irem
    Intuitionistic fuzzy sets (Atanassov, 1986) are the sets whose elements have degrees of membership and non-membership satisfying the condition that their sum is at most equal to one. Thus, an expert can express his/her hesitancy through IFS whereas it is not possible with ordinary fuzzy sets. This paper presents a literature review on intuitionistic fuzzy sets based on some classifications with respect to type of intuitionistic fuzzy numbers. We use graphical and tabular illustrations for a better visualization of the review. We also propose a new extension of IFS whose name is q-Spherical fuzzy sets.
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    A novel circular intuitionistic fuzzy AHP&VIKOR methodology: An application to a multi-expert supplier evaluation problem
    (PAMUKKALE UNIV, 2022-03-16) Otay, İrem; Kahraman, Cengiz
    Abstract: VIKOR method being one of the frequently used Multi-Criteria Decision Making (MCDM) methods, is based on the distances of alternatives to positive and negative ideal solutions, and presents compromising solutions. AHP is another MCDM method dividing the big problem into small and manageable problems through pairwise comparisons of criteria and alternatives. In these methods, linguistic assessments are generally preferred since exact numerical assignments of criteria values are really difficult and experts can not reflect the thoughts in their minds with crisp numbers. The fuzzy set theory captures the vagueness and impreciseness in these linguistic assessments successfully thorough fuzzy numbers. Circular intuitionistic fuzzy sets (C-IFS) are the latest extension of ordinary fuzzy sets, which was introduced by Atanassov [1]. C-IFS help experts to define membership (belongingness) and nonmembership (unbelongingness) degrees by incorporating the uncertainty of these degrees. In this paper, an integrated C-IF AHP & CIF VIKOR methodology is developed and applied to a multi-expert supplier evaluation problem. The results obtained from the proposed methodology are compared with other methods, and a sensitivity analysis is performed as well.
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    A novel interval valued circular intuitionistic fuzzy AHP methodology: Application in digital transformation project selection
    (Elsevier Science Inc, 2023) Otay, Irem; Onar, Sezi Cevik; Oztaysi, Basar; Kahraman, Cengiz
    Since its first introduction, ordinary fuzzy sets have been extended to new types of fuzzy sets as a tool of artificial intelligence techniques. One of the recently introduced fuzzy sets, Circular Intuitionistic Fuzzy (CIF) sets enable us to take into account instability of the membership and non-membership degrees with a circular area & its radius. In this study, we first introduce Interval Valued CIF (IVCIF) sets and their arithmetic operations to better incorporate the uncertainty and cover a broader domain. Then, we introduce a novel IVCIF Analytic Hierarchy Process (AHP) method and apply it to evaluate Digital Transformation (DT) projects with complex nature. DT projects requiring fundamental changes in processes, business models and cultures of the com-panies, contribute a significant value to the companies and increase their market shares; so that they can achieve long term success and competitive advantage. On the other hand, DT problems which are usually ill-defined and include incomplete information based on human judgments, necessitate fuzzy representation. For the success of a digital transformation and to contribute excellence in engineering applications, DT projects should be carefully analyzed. For these rea-sons, we focus on DT project evaluation problem in application. Also, sensitivity & comparative analyses are performed.
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    A novel single-valued spherical fuzzy AHP-WASPAS methodology
    (World Scientific Publ Co Pte Ltd, 2020) Otay, Irem; Kahraman, Cengiz; Oztaysi, Bapr; Onar, Sezi Cevik
    Intuitionistic fuzzy sets are the main source of several recent extensions of the ordinary fuzzy sets such as Pythagorean fuzzy sets, picture fuzzy sets, neutrosophic sets and qrung orthopair fuzzy sets. In addition to these, one of the latest extensions of these types of fuzzy sets is Spherical fuzzy sets, which have been often employed in many multiattribute decision making applications in the literature. One of the advantages of Spherical fuzzy set is that it provides a larger domain for the definition of the parameters (membership & non-membership functions and hesitancy) and it allows the parameters to be defined independently. Analytic Hierarchy Process (AHP) is one of the multi-attribute decision making methods based on pairwise comparisons of criteria and alternatives, satisfying the consistency of each pairwise comparison matrix. WASPAS (The Weighted Aggregates Sum Product Assessment) being the integration of weighted product sum and simple additive weighting methods, has been recently introduced to the literature. Under impreciseness and vagueness, linguistic evaluations are generally preferred in a decision matrix. There are many fuzzy extensions of AHP & WASPAS methods such as intuitionistic fuzzy AHP, intuitionistic fuzzy WASPAS, and Pythagorean fuzzy AHP. However, there is no paper integrating AHP and WASPAS methods using Spherical fuzzy sets. Thus, this paper aims to contribute to the literature by developing an integration of Spherical fuzzy AHP &WASPAS methods. The proposed method is applied to solve outsource manufacturer evaluation and selection problem.
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    Project risk evaluation using a fuzzy analytic hierarchy process: An application to information technology projects
    (Wiley, 2006) Tuysuz, Fatih; Kahraman, Cengiz
    Projects are critical to the realization of performing organization's strategies. Each project contains some degree of risk and it is required to be aware of these risks and to develop the necessary responses to get the desired level of project success. Because projects' risks are multidimensional, they must be evaluated by using multi-attribute decision-making methods. The aim of this article is to provide an analytic tool to evaluate the project risks under incomplete and vague information. The fuzzy analytic hierarchy process (AHP) as a suitable and practical way of evaluating project risks based on the heuristic knowledge of experts is used to evaluate the riskiness of an information technology (IT) project of a Turkish firm. The means of the triangular fuzzy numbers produced by the IT experts for each comparison are successfully used in the pairwise comparison matrices. (c) 2006 Wiley Periodicals, Inc.
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    q-spherical fuzzy sets and their usage in multi-attribute decision making
    (World Scientific Publ Co Pte Ltd, 2020) Kahraman, Cengiz; Oztaysi, Basar; Onar, Sezi Cevik; Otay, Irem
    Intuitionistic fuzzy sets (IFS) have been very popular in the literature after they were introduced by Atanassov (1986). Several extensions of IFS have been proposed such as Pythagorean fuzzy sets (PFS), fermatean fuzzy sets (FFS), q-rung orthopair fuzzy sets, picture fuzzy sets (PiFS), and spherical fuzzy sets (SFS). The main difference among these extensions is the number of independent membership function parameters such as membership degree, non-membership degree, and hesitancy degree. Similar to q-rung orthopair fuzzy sets, picture fuzzy sets can be extended to q-spherical fuzzy sets. This idea is handled in this paper and some operations of q-Spherical fuzzy sets are presented.
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    Score and accuracy functions for different types of spherical fuzzy sets
    (World Scientific Publ Co Pte Ltd, 2020) Otay, Irem; Kahraman, Cengiz; Oztaysi, Basar; Onar, Sezi Cevik
    Spherical fuzzy sets are the latest extension of the ordinary fuzzy sets, which are based on three independent parameters, namely membership degree, non-membership degree and hesitancy degree. The squared sum of these parameters must be equal or less than 1. Several papers have been published on the arithmetic operations, aggregation operators, defuzzification operations and many others in the literature. However, there are still gaps in these operations for different types of spherical fuzzy numbers such as triangular, trapezoidal, and left-right (LR) fuzzy numbers. In this paper, we focus on score and accuracy functions for several types of spherical fuzzy numbers by illustrating numerical examples.
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    Selection of learning analytics projects by using spherical fuzzy TOPSIS
    (World Scientific Publ Co Pte Ltd, 2020) Onart, Sezi Cevik; Kahraman, Cengiz; Oztaysi, Basar; Otay, Irem
    Learning analytics is the measurement of student progress by the collecting, analysis and reporting data in the learning environment. Learning analytics methods try to find out the dependent pattern in dataset gathered. Learning Analytics improve student outcomes in several ways, first, using learning analytics leads to measure student success correctly. With this information students can find accurate teaching techniques and support themselves. Also, it gives proper and faster feedback about learning technique to the stakeholders (principals, teachers, parents). The scope and the aim of learning analytic projects may differ for different organizations. Selecting the right learning analytic project is crucial for the overall success of the learning process. Despite their benefits, while selecting the learning analytic projects not only financial benefits but also various factors including Privacy, Access, Transparency, Security, Accuracy, Restrictions, and Ownership should be taken into account. Yet, evaluating these factors is not easy since they involve uncertainties. Therefore, the selection of learning analytic projects is a complex process that includes various uncertainties. In this study, we utilize an Spherical fuzzy TOPSIS approach for selecting Learning Analytics Projects This method enabled us defining the uncertainties with independent parameters.