Browsing by Author "Afsar, O"

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    Generalized cluster variation theory for the isotropic-nematic phase transition
    Afsar, O; Kayacan, O
    In this study, a cluster variation theory for the Maier-Saupe model of the nematic-isotropic phase transition is generalized by using non-extensive thermostatistics. The variation of long-range order parameter with temperature is investigated and the effect of the possible generalization is shown for some values of the entropic index. The critical value of the long-range order parameter at the nematic-isotropic transition temperature versus the entropic index is also compared with Monte Carlo simulation values and experimental data.
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    Application for Tsallis thermostatistics to half-width method used in thermoluminescence glow peaks in analysis of thermal desorption spectra
    Kayacan, O; Can, N; Karabulut, Y; Afsar, O
    Several methods have been developed in the analysis of the thermoluminescence glow peaks, and in particular when applied to thermoluminescence (TL) dosimetry and TL dating of archaeological and geological minerals. Some of these methods are identical to those developed for the study of thermal desorption. Such a method is called half-width method where a shape factor is introduced. Recently TL decay and thermal desorption process have been studied using a nonextensive formalism, namely Tsallis thermostatistics. In the present work, we consider the half-width method because it is the easiest one to estimate the activation energy. Importantly, we give the generalized form of the activation energy for all order of kinetics. We also investigate the influence of the nonextensivity on the shape factor parameter and on the activation energy. (C) 2004 Elsevier B.V. All rights reserved.