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    An interval type-2 fuzzy ELECTRE approach for assessing ballast water treatment systems for ships
    (Springer Science and Business Media Deutschland GmbH, 2024) Bashan, Veysi; Demirel, Hakan; Kaya, Ahmet
    The transportation of dangerous aquatic organisms and pathogens in ballast tanks causes problems on a global scale and therefore, The International Maritime Organization (IMO) has put into force the “International Convention for the Control and Management of Ships’ Ballast Waters and Sediments”. There are many ballast water treatment systems (BWTS) available in the market. The most important issue in the integration of the systems to the ships is to have technical information about the available options and to determine the most suitable solution for the ship among these alternatives. For this, the interested parties need to make an appropriate choice by knowing the features, advantages, and disadvantages of the BWTSs. The main aim of this article is to assess the five types of BWTS technologies that are frequently used and to make an optimum choice by consulting the opinions of experts in the sector. In this context, this study used the fuzzy ELECTRE (ELimination Et Choix Traduisant la REalite’) method and proposed a novel approach for handling BWTS selection based upon interval type-2 fuzzy sets. It has been evaluated that a hybrid system in which filtration + ultrasound + ultraviolet (UV) systems can be used together would be more appropriate. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    An interval type-2 fuzzy enhanced best-worst method for the evaluation of ship diesel generator failures
    (PERGAMON-ELSEVIER SCIENCE LTD, 2022) Yucesan, Melih; Başhan, Veysi; Demirel, Hakan; Gul, Muhammet
    The environmental destruction in our century necessitates the implementation of more safety-based rules and the strict implementation of failure analysis, especially in the maritime sector. The generator system, considered the ship's powerhouse, is expected to be ready and well-maintained for efficient and safe operations. This study proposes a new methodology to analyze ship generator failures. This method includes a version of the best-worst multi-criteria decision-making method enriched with interval type-2 fuzzy logic (IT2FE-BWM). Enrichment with interval type-2 fuzzy numbers shows that a parameter about how much the decision-maker trusts the pairwise comparisons are added to the model. Thus, a more sensitive methodology has been proposed for the confidence of the maritime sector evaluators. A solid decision mechanism has been developed to prioritize generator failures. In addition, a comparison study with some other BWM derivatives and a creative sensitivity analysis were added to this study and its robustness was tested.
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    Evaluation of critical problems of heavy fuel oil separators on ships by best-worst method
    (Sage Publications Ltd, 2022) Bashan, Veysi; Demirel, Hakan; Celik, Erkan
    It is known that trade by ship is a cheaper way than airway, land, and rail trade. One of the most important reasons for this is that ships use heavy fuel oil (HFO), which is cheap but also poor quality fuel. This HFO used in ships needs to be cleaned with machines called separators (purifiers). Therefore, the separator is one of the vital auxiliary machines on the ship. A satisfactory separation should be done in order to get rid of the effects such as water in the fuel, sludge formation, pump ability, mixing of different grades in the tanks, abrasion, and corrosion, which are the most important risks in the burning of fuel oil. Many problems are encountered while trying to make good separation. Therefore, in this article, 20 important problems that are frequently encountered in ship HFO separators are evaluated with the best-worst method (BWM) by consulting marine experts. Results show that dirty separator discs (also fractured or broken), wrong gravity disc choice (or bad interface position), and unsatisfactory bowl work are the most important problems among 20 critical and frequent separator problems. Problems and results are very important in terms of smooth ship machinery operations and we think that this study will close this gap in the literature by ordering and identifying problems and also solution recommendations.
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    Health, safety, and environmental failure evaluation by hybridizing fuzzy multi-attribute decision-making methods for maritime scrubber systems
    (Springer, 2022) Bashan, Veysi; Yucesan, Melih; Demirel, Hakan; Gul, Muhammet
    Many shipping companies have started using scrubbers in their fleet to eliminate sulfur emissions from ships, per IMO (International Maritime Organization) rules. Before and during the scrubbers' selection, the scrubbers' operational failures have also started to appear and cause serious concerns. In this study, classified scrubber types are explained and open type, closed type, and hybrid scrubber systems are evaluated. To contribute to this gap in the literature, scrubber failures were identified, five experts with different perspectives were consulted, and the most common and critical malfunctions were evaluated with the fuzzy best-worst method (F-BWM) and fuzzy technique for order preference by similarity to an ideal solution (F-TOPSIS). F-BWM was used to determine the importance weights of the risk parameters used in evaluating failures since it provides fewer comparisons among pairwise comparison-based decision-making methods and a more consistent judgment in the evaluation. F-TOPSIS, on the other hand, was used to determine the final priority scores of the scrubber failures, taking into account the risk parameter weights obtained in the first stage. It has been preferred due to its easy to useness and based on its closeness to the ideal solution and applicability to risk and failure analysis problems. Considering all different systems in general, important issues such as collection efficiency, sulfur emission problem, abrasion, leakages, pump failures, heat exchanger failures, air fan sealing failures, sensors and failures in monitoring the whole system have been investigated. Results show that too high axial velocity for separator and flooded separator, too high solids concentration in recirculation liquid (SF2), piping leakages (SF5), poor quality or inappropriate consumables and chemicals (SF11), and feed circulation pump problems (SF6) are found to be the most important problems among thirteen failures.