Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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2005 - 200932010 - 20141

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Now showing 1 - 4 of 4
  • Master Thesis
    Two Numerical Approaches for Solving Nonlinear Stiff Differential Equations
    (Izmir Institute of Technology, 2014) İmamoğlu, Neslişah; Tanoğlu, Gamze
    This thesis presents two different numerical methods to solve non-linear stiff differential equations. The first method is exponential integrator, its error bounds are derived for the specific differential equations. Error analysis of exponential integrators is studied based on the Frèchet differentiation and Sobolev space. We obtain the error bounds in Hs(R) norms under the certain assumptions. The second method is a new iterative linearizaton technique. For the second one, we first time applied to general Frèchet derivative as a linearization technique for the numerical solution of nonlinear partial differential equations. In computational part, in order to denote the effectiveness of the new proposed method, we compare our proposed method with the well-known techniques with respect to the errors.
  • Master Thesis
    Nonlinear Euler Poisson Darboux Equations Exactly Solvable in Multidimensions
    (Izmir Institute of Technology, 2008) Ateş, Barış; Pashaev, Oktay
    The method of spherical means is the well known and elegant method of solving initial value problems for multidimensional PDE. By this method the problem reduced to the 1+1 dimensional one, which can be solved easily. But this method is restricted by only linear PDE and can not be applied to the nonlinear PDE. In the present thesis we study properties of the spherical means and nonlinear PDE for them. First we briefly review the main definitions and applications of the spherical means for the linear heat and the wave equations. Then we study operator representation for the spherical means, especially in two and three dimensional spaces. We find that the spherical means in complex space are determined by modified exponential function. We study properties of these functions and several applications to the heat equation with variable diffusion coefficient.Then nonlinear wave equations in the form of the Liouville equation, the Sine-Gordon equation and the hyperbolic Sinh-Gordon equations in odd space dimensions are introduced. By some combinations of functions we show that models are reducible to the 1+1 dimensional one on the half line.The Backlund transformations and exact particular solutions in the form of progressive waves are constructed. Then the initial value problem for the nonlinear Burgers equation and the Liouville equations are solved. Application of our solutions to spherical symmetric multidimensional problems is discussed.
  • Master Thesis
    Exact Solution of Some Nonlinear Differential Equations by Hirota Method
    (Izmir Institute of Technology, 2005) Güçoğlu, Deniz Hasan; Tanoğlu, Gamze
    The Hirota Bilinear Method is applied to construct exact analytical one solitary wave solutions of some class of nonlinear differential equations. first one the system of multidimensional nonlinear wave equation with the reaction part in form of the third order polynomial determined by three distinct constant vectors. Second one is the mixed diffusion wave equation in one dimension. The bilinear representation is derived by extracting one of the vector roots (unstable in general). This allows us reduce the cubic nonlinearity to a quadratic one. In our approach, the velocity of solitary wave is xed by truncating the Hirota perturbation expansion and it is found in terms of all three roots. Furthermore, Hirota Bilinear Method is also proposed to solve Brusselator reaction model. The simulations of solutions are illustrated for diffusion wave equation in one dimension. The bilinear representation is derived by extracting one of the vector roots (unstable in general). This allows us reduce the cubic nonlinearity to a quadratic one. In our approach, the velocity of solitary wave is xed by truncating the Hirota perturbation expansion and it is found in terms of all three roots.Furthermore, Hirota Bilinear Method is also proposed to solve Brusselator reaction model.The simulations of solutions are illustrated for different polynomial roots and parameters as well.
  • Master Thesis
    The Solution of Some Differential Equations by Nonstandard Finite Difference Method
    (Izmir Institute of Technology, 2005) Kıran Güçoğlu, Arzu; Tanoğlu, Gamze
    In this thesis, the nonstandard finite difference method is applied to construct thenew finite difference equations for the first order nonlinear dynamic equation, second order singularly perturbed convection diffusion equation and nonlinear reaction diffusion partial differential equation The new discrete representation for the first order nonlinear dynamic equation allows us to obtain stable solutions for all step-sizes.For singularly perturbed convection diffusion equation, the error analysis reveals that the nonstandard finite difference representation gives the better results for any values of the perturbation parameters. Finally, the new discretization for the last equation is obtained.The lemma related to the positivity and boundedness conditions required for the nonstandard finite difference scheme is stated. Numerical simulations for all differential equarions are illustrated based on the parameters we considered.