Browsing by Author "Deǧer G."

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    Strength of wheat and barley stems and design of new beam/columns
    (2010) Deǧer G.; Pakdemirli M.; Candan F.; Akgün S.; Boyaci H.
    In this study, physical and mechanical properties of wheat and barley stems are examined. Transverse sections of the stems are magnified by a microscope and the material structure in the transverse sections are analysed with image processing programs. Geometric properties such as inner, outer radius, stem wall thickness and density variation of the material along the radius are measured and density variations are approximated by a mathematical model. Moment of inertia of the cross-sectional area which plays a vital role in resistance against bending and buckling is calculated approximately. Using the material density variations of the wheat (Triticum sativum L.) stems, new beam/columns are designed. Stress distributions in this new design and conventional designs of equivalent weight are compared using ANSYS program. It is found that stresses are more uniformly distributed in the new design with maximum stresses being lower than the conventional designs. © Association for Scientific Research.
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    Symmetry analysis of boundary layer equations of an upper convected Maxwell fluid with magnetohydrodynamic flow
    (Verlag der Zeitschrift fur Naturforschung, 2011) Deǧer G.; Pakdemirli M.; Aksoy Y.
    Steady state boundary layer equations of an upper convected Maxwell fluid with magnetohydrodynamic (MHD) flow are considered. The strength of the magnetic field is assumed to be variable with respect to the location. Using Lie group theory, group classification of the equations with respect to the variable magnetic field is performed. General boundary conditions including stretching sheet and injection are taken. Restrictions imposed by the boundary conditions on the symmetries are discussed. Special functional forms of boundary conditions for which similarity solutions may exist are derived. Using the symmetries, similarity solutions are presented for the case of constant strength magnetic field. Stretching sheet solutions with or without injection are presented. Effects of physical parameters on the solutions are depicted. © 2011 Verlag der Zeitschrift für Naturforschung, Tübingen.