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    A New Circular Intuitionistic Fuzzy MCDM: A Case of Covid-19 Medical Waste Landfill Site Evaluation
    (IEEE, 2021) Cakir, Esra; Tas, Mehmet Ali; Ulukan, Ziya
    Since the beginning of the COVID-19 pandemic, the use of protective medical products has tremendously increased. The wastes generated by used products pose a threat to public health. Selection of alternative landfill sites to be determined for medical waste is a challenging task as there are several criteria to consider. Fuzzy multi-criteria decision making (MCDM) approaches can be employed to overcome this problem. In this study, the landfill sites evaluation for Covid-19 pandemic medical waste is investigated. Decision-makers give their judgments with intuitionistic fuzzy numbers and a novel circular intuitionistic fuzzy MCDM approach is developed for evaluating sites. As a contribution to the literature, this study extends the usage of circular intuitionistic fuzzy sets (C-IFS) in MCDM approaches by proposing defuzzification functions. The application of the proposed method is intended to guide future C-IFS MCDM methodologies.
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    Circular Intuitionistic Fuzzy Sets in Multi Criteria Decision Making
    (Springer Science and Business Media Deutschland GmbH, 2022) Çakır, Esra; Taş, Mehmet Ali; Ulukan, Ziya
    Collaborating businesses are expected to be mutually beneficial and act as a single entity. It is possible to achieve the goals thanks to the businesses that come together in an industrial symbiosis network. Two (or more) businesses benefit in an industrial symbiosis relationship. The selection of enterprises in which industrial symbiosis can be established is a difficult task due to the different criteria that must be considered. In this study, the assessment of companies for industrial symbiosis is examined. The alternatives are evaluated with circular intuitionistic fuzzy numbers according to the criteria by experts, and a new circular intuitionistic fuzzy MCDM approach is developed. In addition to the existing literature, this study contributes to the circular intuitionistic fuzzy sets by proposing a new score function. This application is intended to guide future circular intuitionistic fuzzy MCDM approaches. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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    Cylindrical neutrosophic fuzzy heuristic approach to locate mobile pandemic test labs
    (IEEE, 2021) Çakır, Esra; Taş, Mehmet Ali; Ulukan, Ziya
    Since 2020, the world is facing a pandemic. In order to cope with the epidemic, the acceleration of the diagnosis process is important for treatment. However, in order to minimize contact with other patients, test centers should also be kept separate from public health centers. In this study, a multi facility location problem is addressed for mobile pandemic test labs to serve people in certain regions in Turkey. Experts in the health sector are asked to make decisions in this process. Considering the uncertainties in human nature, cylindrical neutrosophic fuzzy numbers are used for expert evaluations. According to the views of decision makers, weights are calculated to alternative locations by a fuzzy MCDM procedure. The cylindrical neutrosophic fuzzy heuristic algorithm is proposed for the assignment of mobile pandemic test labs serving the regions to alternative locations. The results are intended to guide future studies.
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    Cylindrical Neutrosophic Single-Valued Fuzzy MCDM Approach on Electric Vehicle Charging Station Relocation with Time-Dependent Demand
    (Springer Science and Business Media Deutschland GmbH, 2022) Çakır, Esra; Taş, Mehmet Ali; Ulukan, Ziya
    The use of electric vehicles has been increasing rapidly in recent years. Hence, determining the location of charging stations is a strategic decision. Managements may consider relocating charging stations as demand may change over time. In order to reflect the uncertainty in demand, it is appropriate to use fuzzy expressions. The demands of customers at present time can be calculated according to the criteria determined by using the fuzzy evaluations of decision makers. In this study, the single facility relocation problem for time-dependent demand is examined on finite time horizon. Rectilinear distance is considered. Demands of locations are calculated according to the criteria set by decision makers using cylindrical neutrosophic single-valued fuzzy expressions. This methodology is applied to the problem of minimum cost location of electric charging stations. The time-dependent demands of customers are determined with the help of cylindrical neutrosophic single-valued numbers. The minimum cost of relocating the charging station in a ten-year period is investigated. This application is intended to guide future facility relocation approaches. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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    Neutrosophic Fuzzy MARCOS Approach for Sustainable Hybrid Electric Vehicle Assessment
    (IEEE, 2021) Cakir, Esra; Tas, Mehmet Ali; Ulukan, Ziya
    In smart city planning, activities that minimize the damage to the environment are important for a sustainable environment. Therefore, municipalities have tended to change their vehicle preferences for sustainable environmental goals. In recent years, the use of hybrid electric vehicles has been on the agenda in terms of reducing environmental pollution. Municipalities need some criteria and expert opinion to choose among the alternatives. The contribution of this paper is to propose a new single valued neutrosophic fuzzy integrated MARCOS method for fuzzy multi-criteria decision making problems. The uncertain decisions of experts are included to MARCOS method to express the uncertainties in human opinions, therefore, the single valued neutrosophic fuzzy numbers are preferred in terms of truth, indeterminacy and falsity membership. The method is used to rank the alternatives keeping determined criteria by DMs in consideration. It finds ideal and anti-ideal solutions by decision matrix, and it uses these values to generate the utility degrees of the alternatives. The proposed methodology is applied on sustainable hybrid electric vehicle selection problem for a municipality in Turkey. The results are comparatively represented.
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    Spherical bipolar fuzzy weighted multi-facility location modeling for mobile COVID-19 vaccination clinics
    (IOS Press, 2022) Çakır, Esra; Taş, Mehmet Ali; Ulukan, Ziya
    A pandemic was declared in 2020 due to COVID-19. The most important way to deal with the virus is mass vaccination which is a complex task in terms of fast transportation and process management. Hospitals and other health centers are appropriate for vaccination process. In addition, in order to protect other patients from COVID-19 and provide rapid access to vaccines, mobile vaccination clinics can also be considered. In this study, the location assignments of mobile vaccination clinics that can serve some regions of three cities in Turkey are examined. The linear formulation of the problem is given, and the multi-facility location problem for COVID-19 vaccination is investigated with Lagrange relaxation and modified saving heuristic algorithm. For the proposed fuzzy MCDM integrated saving heuristic, the importance of candidate locations is calculated with the aid of decision makers who give their views in spherical bipolar fuzzy information. The results of different approaches are compared, and it is intended to guide future studies.
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    Spherical fuzzy swara-marcos approach for green supplier selection
    (3Ciencias, 2021) Taş, Mehmet Ali; Çakır, Esra; Ulukan, Ziya
    In a supply chain management, supplier selection is an important step to determine the structure of the model. Multi-criteria decision making methods are appropriate tools for dealing with the selection of suitable suppliers. In addition, fuzzy multi-criteria decision making approaches are helpful to include different and uncertain views of decision makers. In this study, a new combined fuzzy methodology is proposed to handle green supplier selection problem. The proposed model consists of a spherical fuzzy-SWARA method, which is used to calculate the criteria weights, and MARCOS method, which is applied to rank the alternatives. In the case study, green supplier selection problem of a textile company located in Turkey is discussed. Six alternative suppliers are evaluated against twelve green criteria, and alternatives are ranked. Finally, a sensitivity analysis is performed to compare the results of different scenarios.