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    A new model for deformed carbon nanotubes using Green's function

    , Article Applied Physics A: Materials Science and Processing ; Volume 105, Issue 4 , 2011 , Pages 875-880 ; 09478396 (ISSN) Fathi, D ; Sarvari, R ; Sharif University of Technology
    A new method for modeling and analysis of deformed carbon nanotubes (CNTs) using Green's function, is presented in this paper, for the first time. Using the proposed method, a new circuit model is obtained for the deformation region of a deformed single-walled CNT (SWCNT), which the values of its elements depend on the type of deformation and also the deformation parameters such as the coupling matrices and the energy variations of deformation region. The comparison between the obtained results from the analysis of proposed model and the literature gives a good match which approves the accuracy and correctness of the proposed model  

    Permeability impairment study due to asphaltene deposition: experimental and modeling approach

    , Article Transport in Porous Media ; Volume 91, Issue 3 , February , 2012 , Pages 999-1012 ; 01693913 (ISSN) Bolouri, S. H ; Ghoodjani, E ; Sharif University of Technology
    This fact is well known that during any scenario of production, asphaltene deposition in porous media has a substantial effect on oil flow. But a clear understanding of asphaltene deposition mechanisms can help to minimize asphaltenic problem in oil-bearing formations. In this study, the experimental results of three dynamic CO 2 miscible injection tests were investigated. Regarding the effects of adsorption, mechanical entrapment, and sweeping mechanisms on permeability behavior, a mathematical mass and permeability variation model were developed. According to the experimental results asphaltene deposition causes a 70% loss of sand stone initial permeability while the loss is significantly... 

    Aeroelastic stability consideration of supersonic flight vehicle using nonlinear aerodynamic response surfaces

    , Article Journal of Fluids and Structures ; Volume 25, Issue 6 , 2009 , Pages 1079-1101 ; 08899746 (ISSN) Fathi Jegarkandi, M ; Nobari, A. S ; Sabzehparvar, M ; Haddadpour, H ; Sharif University of Technology
    Aeroelastic stability of a flexible supersonic flight vehicle is considered using nonlinear dynamics, nonlinear aerodynamics, and a linear structural model. Response surfaces including global multivariate orthogonal modeling functions are invoked to derive applied nonlinear aerodynamic coefficients. A modified Gram-Schmidt method is utilized to orthogonalize the produced polynomial multivariate functions, selected and ranked by predicted squared error metric. Local variation of angle-of-attack and side-slip angle is applied to the analytical model. Identification of nonlinear aerodynamic coefficients of the flight vehicle is conducted employing a CFD code and the required analytical model... 

    Aeroelasticity consideration of supersonic vehicle using closed form analytical aerodynamic model

    , Article Aircraft Engineering and Aerospace Technology ; Volume 81, Issue 2 , 2009 , Pages 128-136 ; 00022667 (ISSN) Fathi Jegarkandi, M ; Salezadeh Nobari, A ; Mahdi, S ; Hassan, H ; Farhad, T ; Sharif University of Technology
    Purpose - The purpose of this paper is to investigate the aeroelastic behavior of a supersonic flight vehicle flying at moderate angles of attack using global analytic nonlinear aerodynamic model. Design/methodology/approach - Aeroelastic behavior of a supersonic flight vehicle flying at moderate angles of attack is considered, using nonlinear aerodynamics and linear elastodynamics and structural models. Normal force distribution coefficient over the length of the vehicle and pitching moment coefficient are the main aerodynamic parameters used in the aeroelastic modeling. It is very important to have closed form analytical relations for these coefficients in the model. They are generated...