Yazar "Tarhan, Ismail" seçeneğine göre listele

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    Öğe
    Energy distributions in Szekeres type I and II space-times
    (Polish Acad Sciences Inst Physics, 2006) Aygun, Sezgin; Aygun, Melis; Tarhan, Ismail
    In this study, in context of general relativity we consider Einstein, Bergmann-Thomson, Moller and Landau-Lifshitz energy-momentum definitions and we compute the total energy distribution (due to matter and fields including gravitation) of the universe based on Szekeres class I and class II space-times. We show that Einstein and Bergmann-Thomson definitions of the energy-momentum complexes give the same results, while Moller's and Landau-Lifshitz's energy-momentum definition does not provide same results for Szekeres class II space. The definitions of Einstein, Bergmann-Thomson and Moller definitions of the energy-momentum complexes give similar results in Szekeres class I space-time.
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    Energy momentum of marder universe in teleparallel gravity
    (Springer/Plenum Publishers, 2007) Ayguen, Sezgin; Baysal, Huesnue; Tarhan, Ismail
    In order to evaluate the energy distribution (due to matter and fields including gravitation) associated with a space-time model of cylindrically-symmetric Marder universe, we consider the Moller, Einstein, Bergmann-Thomson and Landau-Lifshitz energy and momentum definitions in the teleparallel gravity (TG). The energy-momentum distributions are found to be zero. These results are the same as a previous works of Aygun et al., they investigated the same problem in general relativity (GR) by using the Einstein, Moller, Bergmann-Thomson, Landau-Lifshitz (LL), Papapetrou, Qadir-Sharif and Weinberg's definitions. These results support the viewpoints of Banerjee-Sen, Xulu, Radinschi and Aydogdu-Salt1. Another point is that our study agree with previous works of Cooperstock-Israelit, Rosen, Johri et al. This paper indicates an important point that these energy-momentum definitions agree with each other not only in general relativity but also in teleparallel gravity. It is also independent of the teleparallel dimensionless coupling constants, which means that it is valid not only in the teleparallel equivalent of general relativity, but also in any teleparallel model.
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    Investigation of offshore wind characteristics for the northwest of T?rkiye region by using multi-criteria decision-making method (MOORA)
    (Elsevier, 2022) Basaran, Hasan Hakan; Tarhan, Ismail
    The trend towards clean and natural energy sources is inevitable in light of the growing demand for energy in the current age. In line with these needs, the tendency for wind energy is unavoidable, and it is increasing every year. For this reason, in addition to onshore wind energy fields, there is an obligation to use offshore ones. Since it has a high rate of wind energy efficiency, it has become important to install wind power plants on offshore sites in recent years. Although there are no offshore wind power plants in Turkiye yet, studies are ongoing. Data ob-tained from WindPro software between 1992 and 2022 were used for the analysis of the wind energy potential of the Northwest (i.e. South Marmara) region of Turkiye. To select the most suitable location for offshore wind turbines, the analysis was carried out using the MOORA method, which is one of the multi-criteria decision -making methods. According to the obtained data and the selected criteria, the most suitable places in the Southern Marmara Region were sorted.
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    Scalar field theory and energy-momentum problem of Yilmaz-Rosen metric in general relativity and teleparallel gravity
    (Springer, 2008) Aygun, Sezgin; Tarhan, Ismail; Baysal, Huesnue
    In this paper, using the energy momentum definitions of the Einstein, Bergmann-Thomson, Landau-Lifshitz and Moller in general relativity (GR) and teleparallel gravity (TG), we have evaluated the energy-momentum distributions of Yilmaz-Rosen metric. We have obtained that these different energy-momentum definitions give different results in GR and TG. Furthermore these results are same in different gravitation theories and we get that both general relativity and teleparallel gravity are equivalent theories for Einstein, Bergmann-Thomson and Landau-Lifshitz prescriptions. Also, while the Moller energy definitions are same and zero but the momentum prescriptions are disagree in GR and TG.
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    Some string cosmological models in cylindrically symmetric inhomogeneous universe
    (2001) Baysal, Hüsnü; Yavuz, Ilhami; Tarhan, Ismail; Camci, U?ur; Yilmaz, Ihsan
    The aim of this paper is to investigate the behavior of a string in the cylindrically symmetric inhomogeneous cosmological model. It has been assumed that expansion ? in the model is proportional to ?11 of the eigenvalue of the shear tensor ??mu;. Also, various physical and geometrical properties of the model have been discussed.