Yazar "Yilmaz, Suleyman" seçeneğine göre listele

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    Investigation of anisotropic thermal conductivity of uniaxial and biaxial Gay-Berne particles with molecular dynamics simulation
    (Taylor & Francis Ltd, 2011) Yildirim, Ahmet; Eroglu, Erol; Yilmaz, Suleyman
    In this study, we investigated uniaxial and biaxial Gay-Berne (GB) particles with the help of the molecular dynamics (MD) simulation. Anisotropic thermal conductivities of the uniaxial and biaxial GB liquid crystal molecules were calculated both in the random molecular orientation and in the molecular orientations of 0 degrees, 45 degrees and 90 degrees using the Muller-Plathe method. In the uniaxial molecules, it was found that the thermal conductivity ratios between the parallel and perpendicular components for the smectic and nematic phases are about 2.2:1 and 2.8:1, respectively. As for biaxial molecules, these ratios between the parallel and perpendicular components of molecules for the smectic and nematic phases are about 3.9:1 and 3.8:1, respectively.
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    Investigation of anisotropic thermal conductivity of uniaxial and biaxial Gay–Berne particles with molecular dynamics simulation
    (2011) Yildirim, Ahmet; Eroglu, Erol; Yilmaz, Suleyman
    In this study, we investigated uniaxial and biaxial Gay– Berne (GB) particles with the help of the molecular dynamics (MD) simulation. Anisotropic thermal conductivities of the uniaxial and biaxial GB liquid crystal molecules were calculated both in the random molecular orientation and in the molecular orientations of 08, 458 and 908 using the Müller-Plathe method. In the uniaxial molecules, it was found that the thermal conductivity ratios between the parallel and perpendicular components for the smectic and nematic phases are about 2.2:1 and 2.8:1, respectively. As for biaxial molecules, these ratios between the parallel and perpendicular components of molecules for the smectic and nematic phases are about 3.9:1 and 3.8:1, respectively.
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    Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals in Situ
    (2009) Yilmaz, Suleyman; Yildirim, Ahmet
    In this study, a new experimental study has been implemented to deter- mine the thermal-diffusivity parameters of industrial nematic liquid crystals, 4-pentyl- 4 -cyanobiphenyl (5CB) and 4 -octyl-4-cyanobiphenyl (8CB), both numerically by using the finite difference method (FDM) for forward solutions and experimentally by measuring the temperature variation with time and position. The most important parts of this experimental study are the heating system and the liquid crystal cell, which were constructed in-house to determine the temperatures of the materials in situ. Four different positions for local measurements have been studied, and the opti- mum graph of this variation has been determined. The experimental and theoretical results of this study are consistent with previous measurements performed by means of a conventional thermal technique.
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    Optical Properties of Nematic Liquid Crystal (C 21 H 27 NO 2 S) Under AC/DC Electric Fields
    (2009) Emek, Mehriban; Besli, Nurettin; Yilmaz, Suleyman; Yildirim, Ahmet
    In this study, the effects of the phase transition on the optical transmittance of the nematic liquid crystal C21H27NO2S, 4′-isothiocyanatophenyl-4-pentylbicyclo[2,2,2]octane-1-carboxylate are investigated in terms of temperature variation and rotational angle of the polarizer through electro-optical methods under AC / DC electric fields. It is observed that the domain structure of the material is affected considerably by the applied electric field as the temperature changes. Under applied electric fields, the crystal-nematic (CN) phase-transition point changes and the behaviour of the liquid crystal in the phase-transition region shows some differences. The intensity of the light passing through the system under a DC electric field increases as the electric field rises. Nevertheless, the intensity of the transmitted light under an AC electric field increases at the beginning and then decreases as the electric field rises to a temperature of more than 355 K. These results can be explained through the formation of a domain structure during the phase-transition process and the light scattering caused by these structures.