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Conference Object Optimal Bore Diameter for Power Dense Traction Motor(Transilvania University of Brasov 1, 2025) Siddique, Muhammad Salik; Bülent Ertan, Hulusi; Ertan, H. BulentThe sine-wave permanent magnet brushless machine (PMSM) and Induction machine (IM) are the favorite motor types for traction applications. Modern permanent magnets (PM) are produced only in a few countries, and PM motors have higher efficiency. However, IM offers a robust, mature, rare-earth-material-free, and cost-effective. This study investigates the possibility of increasing IM efficiency by choosing an optimal bore diameter to reduce copper loss. Optimal bore diameter ensures that the motor operates at flux density levels that maintain a high power factor and give the possibility of increasing stator and rotor slot area to reduce copper loss. The investigation here is based on an experimentally verified FE model of the motor. This study illustrates that the rotor copper loss can be reduced by 25% with the choice of optimal bore diameter at rated voltage and frequency. A further 1% copper loss reduction is possible by introducing a sleeve over the stator slots to reduce air gap harmonics and, thus, surface losses on the rotor side. © 2025 Elsevier B.V., All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Efficiency Analysis of Eu and Non-Eu R&d Investor Firms on Matched Samples(Springer, 2023) Belgin, OnderThis study is on the efficiency analysis of EU and non-EU R&D investor firms. The study mainly aims to understand if there is a difference between the efficiency level of EU and non-EU R&D investor firms and what the effecting factors of firm efficiency are. To construct an unbiased group of EU and non-EU firms, propensity score matching (PSM) is employed and thereby the analysis is made with the firms that have similar features. In the efficiency analysis stage, a slacks-based measure data envelopment analysis (SBM DEA) model is used for 2017-2019 period. After that, a panel Tobit regression model is used to examine the factors effecting the efficiency of the EU and non-EU firms. The results showed that EU firms have higher efficiency than non-EU firms only in 2018 and EU firms have very high improvement potential in market capitalization. By panel Tobit regression model, it was understood that capital expenditure intensity has negative effect on both the efficiency of EU and non-EU firms. Size of the firms has negative effect on only non-EU firms.Article Citation - WoS: 14Citation - Scopus: 15A New Axial Flux Permanent Magnet Synchronous Alternator Autonomously Adapted To Wind Speeds(Elsevier Sci Ltd, 2015) Kalender, Osman; Ege, Yavuz; Eskidere, Omer; Karen, Idris; Gurdal, Osman; Unal, Cevat; Kabadayi, MuratIn this study, a new axial flux permanent magnet synchronous generator (PMSA) design and prototyping procedures are presented. It is composed of a stack of rotor-stator blocks on the same shaft. In other words, it is made up of four alternators based on axial flux permanent magnets that can generate electrical energy within the limits of rotor rotational speed with varying wind speeds. A control system is also introduced to the generator. The control system connects or disconnects the stator blocks to the load according to the changing speeds of the wind. It produces electrical energy with stable voltage, frequency and variable power at the output. The efficiency of the generator is tested with different load and speed conditions. It is observed that the efficiency is high when the speed is low in case the load is connected only one stator. The efficiency is high when the speed is above 200 rpm for the case where several stators are connected to the load. It can be seen that the incremental structure of the generator is suitable for changing speeds of the wind. It can have high efficiency for both low and high speeds with changing the number of stator blocks connected to the load. (C) 2015 Elsevier Ltd. All rights reserved.
