Browsing by Author "Sahin C."

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    Principle, design and analysis of a novel axial flux switched reluctance machine with fully pitched winding structure
    (Springer Science and Business Media Deutschland GmbH, 2022) Sahin C.; Karacor M.
    In this study, the fully pitched axial flux switched reluctance machine (FP-AFSRM), which is a new configuration in the literature, was designed and 3D magnetostatic analyses were performed. The focus of the study is to produce higher torque density by simply changing the winding structure. Conventional SRMs are also known as short pitched SRM (SPSRM) since they have a short pitched winding structure. Fully pitched SRMs (FPSRMs) produce higher torque compared to SPSRMs with the mutual coupling effect between phases due to their fully pitched winding structure. In parallel with that, especially for electric vehicles, axial designs have increased gradually instead of radial design of electrical machines. For this purpose, the FP-AFSRM structure was proposed by combining axial design and fully pitched winding structure. The proposed FP-AFSRM model achieved up to 15.07% higher torque density than the basic SP-AFSRM model at different currents and equal copper losses. The proposed FP-AFSRM can be considered as an important alternative machine, especially for electric vehicle technologies and different technological fields, with the advantages of the high torque density and axial geometric structure. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    Design and Finite Element Analysis of a 6/4 Pole Multi-Layer Fully Pitched Switched Reluctance Motor to Reduce Torque Ripple
    (Taylor and Francis Ltd., 2023) Sahin C.; Basaran S.
    —In this study, the design and analysis of multi-layer fully pitched winding switched reluctance motor (MFP-SRM) for general use (submersible pump, electric vehicles, etc.) have been performed. It is seen that the multi-layer switched reluctance motor (SRM) has higher output power when compared to the single-layer SRM. In multi-layer SRM, the motors in the layers are electromagnetically independent of each other although they are identically the same motors with the same characteristics in terms of performance and geometry. Each layer of the MFP-SRM which is designed in this study consists of a 6/4 pole fully pitched SRM (FP-SRM) and these motors are magnetically independent of each other. In the MFP-SRM, which is designed as a double layer, there is a 15° phase difference between the rotor position angles and torque profile curves of each layer. With the phase difference that changes depending on the number of layers, each layer contributes to the total torque production of the profile, ensuring a smooth profile. According to the results of the 3D FEM analysis, it is seen that the proposed multi-layer motor structure has high starting torque and low torque ripple properties. In the analysis carried out in the range of 3–15 Amperes, the torque ripple of the traditional FP-SRM varies between 31.99% and 38.19%, while the torque ripple of the proposed MFP-SRM only varies between 3.23% and 7.11%. © 2023 Taylor & Francis Group, LLC.
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    Comparison of Aluminum and Copper Winding Materials for Switched Reluctance Machines with Finite Element Analysis; [Comparación de materiales de bobinado de aluminio y cobre para máquinas de reluctancia conmutada con análisis de elementos finitos]
    (Universidad Nacional de Colombia, 2023) Sahin C.
    Today, with the decrease in fossil fuel reserves, interest in electric vehicles has grown. Undoubtedly, electric machines are one of the most important parts of electric vehicles. Studies on electrical machines directly affect vehicle performance. Since the electrical machine used is mounted on the vehicle, reducing the total weight without changing the output power will positively affect the overall performance of the vehicle. The windings used to create the magnetic field in electrical machines are made of copper. Electrical machinery manufacturers try to use completely different materials instead of copper or partially reduce its use. At this point, aluminum emerges as an attractive material for various manufacturers. This study analyzed the winding structure of a switched reluctance machine (SRM) proposed for an electric vehicle by using copper and aluminum at an equivalent resistance value, the results of which were compared. As a result of a 2D finite element analysis, it was observed that the machine’s output performance is largely kept when aluminum is used instead of copper for the winding. It was also observed that the aluminum total winding weight decreased by 43,40% compared to that of copper. © 2023, Universidad Nacional de Colombia. All rights reserved.
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    Nationwide prospective audit for the evaluation of appendicitis risk prediction models in adults: Right iliac fossa treatment (RIFT) - Turkey
    (Oxford University Press, 2024) Yalcinkaya A.; Yalcinkaya A.; Balci B.; Keskin C.; Erkan I.; Yildiz A.; Kamer E.; Leventoglu S.; Caglikulekci M.; Zarbaliyev E.; Sevmis M.; Ulgen Y.; Altinel Y.; Meric S.; Akbas A.; Hacim N.A.; Vartanoglu Aktokmanyan T.; Aktimur Y.E.; Calikoglu F.; Gullu H.F.; Durma A.G.; Acar S.; Ciftci E.; Balik E.; Kulle C.B.; Ozata I.H.; Tufekci T.; Tatar C.; Sevinc M.M.; Sevik H.; Ertürk C.; Kiraz I.N.; Ozben V.; Aytac E.; Aliyeva Z.; Mutlu A.U.; Tanal M.; Celayir M.F.; Bozkurt E.; Yetkin S.G.; Ergin E.; Attaallah W.; Uprak T.K.; Omak A.; Simsek O.; Bozkurt M.A.; Kara Y.; Bozdag E.; Yirgin H.; Ozcan A.; Okkabaz N.; Ozdenkaya Y.; Haksal M.C.; Pekuz C.K.; Duru S.; Sivrikoz E.; Ozdemir Y.; Tan N.; Yarbug Karayali F.; Taghiyeva A.; Tirnova I.; Erenler Bayraktar I.; Bayraktar O.; Emsal E.Z.; Dalkilic M.I.; Yesiltas M.; Tok H.; Karakas D.O.; Pusane A.; Demirer A.I.; Sahin H.B.; Gok A.F.K.; Bozkurt H.A.; Yildirim M.; Uzunyolcu G.; Yanar H.T.; Ergun S.; Kutluk F.; Uludag S.S.; Zengin A.K.; Ozcelik M.F.; Sanli A.N.; Altuntas Y.E.; Memisoglu E.; Sari R.; Akdogan O.; Kucuk H.F.; Ozkan O.F.; Ulgur H.S.; Kirkan E.F.; Yuksekdag S.; Rencuzogullari A.; Aktas M.K.; Aba M.; Demirel A.O.; Eray I.C.; Aydogan B.; Cetinkunar S.; Yener K.; Sozutek A.; Irkorucu O.; Bayrak M.; Altintas Y.; Alabaz O.; Atasever A.; Erdogrul G.; Kupeli A.H.; Muhammedoglu B.; Kokdas S.; Kaya M.; Uysal E.; Yildirim A.C.; Zeren S.; Ekici M.F.; Algin M.C.; Kucuk G.O.; Eraslan H.; Aybar E.; Polat S.; Ceylan A.; Isik O.; Kural S.; Aktas A.; Bakar B.; Uzunoglu M.Y.; Gulcu B.; Ozturk E.; Devay A.O.; Taspinar E.; Balcin O.; Aksoy F.; Garip G.; Yalkin O.; Iflazoglu N.; Yigit D.; Kaya R.B.; Ugur M.; Kilic E.; Dedemoglu A.; Arslan R.E.; Temiz M.; Aydin C.; Demirli Atici S.; Kaya T.; Ozturk S.; Calik B.; Kilinc G.; Acar T.; Acar N.; Cengiz F.; Ureyen O.; Tan S.; Ilhan E.; Turk Y.; Durak A.T.; Yilmaz M.; Mercan M.; Atci R.; Sokmen S.; Bisgin T.; Egeli T.; Yildirim Y.; Safak T.; Celik K.; Yilmaz E.M.; Kirnap M.; Demirkiran A.E.; Sekerci U.U.; Karacan E.; Bilgic E.; Ozmen M.M.; Guldogan C.E.; Gundogdu E.; Moran M.; Erol T.; Dincer H.A.; Kirimtay B.; Yilmaz S.; Cennet O.; Yildiz A.; Sahin C.; Akyol C.; Koc M.A.; Ersoz S.; Turhan A.; Konca C.; Tezcaner T.; Erkent M.; Aydin O.; Avci T.; Altiner S.; Osmanov I.; Emral A.C.; Cetinkaya G.; Lapsekili E.; Sakca M.; Cimen S.; Ozen D.; Kozan E.B.; Dogan L.; Haberal E.; Kayhan O.; Aksel B.; Karabacak H.; Azili C.; Yazici F.; Apaydin M.; Kaya I.O.; Cetinkaya E.; Akin T.; Gunes G.; Turap H.; Aslan D.; Demirbag A.E.; Bolukbasi B.; Karaca B.E.; Ozturk E.; Ozeller E.; Kayacan G.S.; Borcek A.O.; Ece I.; Yormaz S.; Colak B.; Calisir A.; Sahin M.; Arslan K.; Hasirci I.; Ulutas M.E.; Metin S.H.; Gultekin F.A.; Ozkan Z.; Ilhan O.; Gundogdu T.; Liman R.K.; Kanat B.H.; Aydin A.; Sungurtekin U.; Ozgen U.; Aykota M.R.; Altintoprak F.; Gonullu E.; Cakmak G.; Dulger U.C.; Mantoglu B.; Demir H.; Akin E.; Eroz E.; Nazli O.; Dere O.; Dadasoglu M.A.; Kara E.; Tutcu S.; Solak I.; Gencer I.; Dalkiran A.; Sevinc B.; Karahan O.; Damburaci N.; Sari E.; Akay T.; Calta A.F.; Ozdemir A.; Ohri N.; Ermis I.; Bozbiyik O.; Ozdemir M.; Goktepe B.; Demir B.; Kilincarslan O.; Gunduz U.R.; Olcum M.; Dincer O.I.; Cakir R.C.; Dinc B.; Sahin E.; Uludag E.; Arslan Y.; Posteki G.; Oktay A.; Tatar O.C.; Guler S.A.; Utkan N.Z.; Tayar S.; Copelci Y.; Kartal M.; Kalayci T.; Yeni M.; Buyukkasap A.C.; Vural S.; Kesicioglu T.; Aydin I.; Gulmez M.; Saracoglu C.; Topcu O.; Kurt A.; Soylu S.; Kurt B.; Serin M.; Basceken S.I.; Gundes E.; Savda M.; Balkan A.Z.A.; Yildiz M.N.; Uzunkoy A.; Karaca E.; Berkan A.; Isik A.; Yildiz Y.A.; Ergul Z.; Yasar N.F.; Badak B.; Ozen A.; Velipasaoglu M.; Ure I.
    Background: Appendicitis is the most prevalent surgical emergency. The negative appendicectomy rate and diagnostic uncertainty are important concerns. This study aimed to assess the effectiveness of current appendicitis risk prediction models in patients with acute right iliac fossa pain. Methods: A nationwide prospective observational study was conducted, including all consecutive adult patients who presented with right iliac fossa pain. Diagnostic, clinical and negative appendicectomy rate data were recorded. The Alvarado score, Appendicitis Inflammatory Response (AIR), Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) and Adult Appendicitis Score systems were calculated with collected data to classify patients into risk categories. Diagnostic value and categorization performance were evaluated, with use of risk category-based metrics including 'true positive rate' (percentage of appendicitis patients in the highest risk category), 'failure rate' (percentage of patients with appendicitis in the lowest risk category) and 'categorization resolution' (true positive rate/failure rate). Results: A total of 3358 patients from 84 centres were included. Female patients were less likely to undergo surgery than men (71.5% versus 82.5% respectively; relative risk 0.866, 95% c.i. 0.834 to 0.901, P < 0.001); with a three-fold higher negative appendicectomy rate (11.3% versus 4.1% respectively; relative risk 2.744, 95% c.i. 2.047 to 3.677, P < 0.001). Ultrasonography was utilized in 56.8% and computed tomography in 75.2% of all patients. The Adult Appendicitis Score had the best diagnostic performance for the whole population; however, only RIPASA was significant in men. All scoring systems were successful in females patients, but Adult Appendicitis Score had the highest area under the receiver operating characteristic curve value. The RIPASA and the Adult Appendicitis Score had the best categorization resolution values, complemented by their exceedingly low failure rates in both male and female patients. Alvarado and AIR had extremely high failure rates in men. Conclusion: The negative appendicectomy rate was low overall, but women had an almost three-fold higher negative appendicectomy rate despite lower likelihood to undergo surgery. The overuse of imaging tests, best exemplified by the 75.2% frequency of patients undergoing computed tomography, may lead to increased costs. Risk-scoring systems such as RIPASA and Adult Appendicitis Score appear to be superior to Alvarado and AIR. © 2024 The Author(s). Published by Oxford University Press on behalf of BJS Foundation Ltd.