PhD Thesis

Browse

Start date: 2010End date: 2019

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Interaction Phenomena of Nonlinear Waves in Unmagnetized Plasmas
    (University of Rajshahi, Rajshahi, 2019) Alam, Mohammad Shah; Talukder, Mamunur Rashid; Ali, M. Hossain
    This dissertation is concerned with the study of interaction phenomena of nonlinear waves in unmagnetized plasmas. The plasma system considered is fully ionized, collisionless and homogeneous and/or inhomogeneous that contains multi-component plasma species under different situations. To investigate the physical issues of the interaction phenomena of nonlinear waves the nonlinear evolution equations are derived. The extended Poincaré-Lighthill-kue (ePLK) method is used to derive the nonlinear evolution equations. The interaction phenomena pertaining to plasma parameters on the production of ion-acoustic solitary waves, ion-acoustic shock waves and rogue waves and their consequences on phase shifts and amplitudes are investigated in different plasma situation. The interaction processes among the waves (such as ion-acoustic solitary waves, ion-acoustic shock waves) for single and multi-soliton plasmas are also studied considering the analytical solutions to the nonlinear evolution equations under some assumptions to discuss the characteristic of the waves in the plasmas that are observed in astrophysical, space and laboratory plasmas. In chapter one, some important physical terms that are relevant to the plasma phenomena are briefly discussed. Chapter two discusses the interaction phenomena of ion-acoustic multi-solition and the production of rogue waves in an unmagnetized plasmas composing non-relativistic as well as relativistic degenerate electrons and positrons, and inertial non-relativistic helium ions. The interaction phenomena are investigated by deriving two-sided Korteweg-de Vries (KdV) equations with their corresponding phase shifts employing extended Poicaré-Lighthill-Kuo (ePLK) method and to study the properties of rogue waves the nonlinear Schrödinger equation (NLSE) is obtained from the modified KdV (mKdV) equation.-------
  • Thumbnail Image
    Item
    Massive Particle Tunneling from Black Hole Spacetime
    (University of Rajshahi, 2013) Hossain, Md. Ilias; Rahman, M. Atiqur
    We investigate the Hawking radiation from different kind of black holes by massive particle tunneling process near the event horizon of the black hole in de Sitter and anti-de Sitter spaces. We calculate the imaginary part of the action from the relativistic Hamilton-Jacobi equation avoid by exploring the equation of motion of the radiation particle in Pain leave coordinate system in order to explore the Hawking non-thermal and purely thermal radiations. The thesis is organized as follows: In chapter 1 we give a brief discussion about our work of studying of massive particle tunneling from black hole space-time. In chapter 2 we review the relativistic Hamilton-Jacobi equation to perform our prime work. In chapter 3 to 10 we investigate the Hawking non-thermal and purely thermal radiations using massive particles tunneling process by employing Hamilton-Jacobi method for Schwarzschild-de Sitter (SdS), Schwarzschild-anti-de Sitter (SAdS), Reissner-Nordström-de Sitter (RNdS), Reissner-Nordström-anti-de Sitter (RNAdS), Kerr-de Sitter (KdS), Kerr-anti-de Sitter (KAdS), Kerr-Newman-de Sitter (KNdS) and Kerr-Newman-anti-de Sitter (KNAdS) black holes. We express the position of all kind of black holes in an infinite series in terms of black hole parameters so that the space-time metric becomes dynamical and derive the new line elements. Taking into account the energy conservation, the angular momentum conservation and the unfixed background spacetime. When self-gravitation interaction is considered, the derived emission/radiation spectrums are not purely thermal and the tunneling rates are related to the change of the Bekenstein-Hawking entropy, which satisfy an underlying unitary theory. Our new process provides an interesting correction to the Hawking pure thermal radiation of the black hole and in the limiting case, the results are accordant with that obtained by Parikh and Wilczek’s method of the black hole.
  • Thumbnail Image
    Item
    Solitary Wave Solutions of NLEEs in Plasma Physics and Engineering
    (University of Rajshahi, 2015) Khan, Md. Ashrafuzzaman; Akbar, Md. Ali
    Although the modified simple equation (MSE) method effectively provides exact solitary wave solutions to nonlinear evolution equations (NLEEs) in the field of applied mathematics, mathematical physics, plasma physics and engineering, it has some limitations. When the balance number is greater than one, usually the method does not give any solution. In this dissertation, we have exposed a process as to how to implement the MSE method to solve the NLEEs for balance number two. In order to verify the process, some NLEEs have been solved by means of this scheme, and we found some fresh traveling wave solutions. When the parameters receive special values, solitary wave solutions are derived from the exact traveling wave solutions and we have analyzed the solitary wave properties by the graphs of the solutions. These solitary wave solutions include soliton, kink shape soliton, singular kink shape soliton, bell shape soliton, singular bell shape soliton, anti-bell shape soliton, singular anti-bell shape soliton, etc. The attraction of the MSE method is that it is consistent, peaceful, authentic, and we found some fresh new traveling wave solutions other than the existing methods, such as, the basic (G /G) -expansion method. We emphasize the implementation of the MSE method, how to examine the solutions to NLEEs for balance number two and also compare the solutions obtained by the MSE method and the well-known existing (G /G) -expansion method. This shows the validity, usefulness, and necessity of the MSE method and our graphical representations describe the obtained traveling wave solutions.