Search for: scattering-cross-section
0.008 seconds

    Calculating the Scattering Cross Section of the Photons Scattered from Particles Associated with the Fifth Force Field in MOG Theory

    , M.Sc. Thesis Sharif University of Technology Mirzavand, Mahdi (Author) ; Rahvar, Sohrab (Supervisor)
    In this thesis, we first review MOdified Gravity (MOG) theory as an alternative to dark matter models and then investigate some of the phenomena related to galaxy dynamics and gravitational lensing within the framework of this theory. In the last step, we present a model for the interaction of the fifth force field and the electromagnetic field. This model is based on the definition of a current density of matter using the energy momentum tensor in which the Lorentz symmetry is broken. This is due to the existence of a constant coefficient in the interaction, which can be considered as a fixed background field or observer 4-velocity that couples to energy momentum tensor. After introducing... 

    Determination of the scattered fields of an SH-wave by an eccentric coating-fiber ensemble using DEIM

    , Article International Journal of Engineering Science ; Volume 46, Issue 11 , 2008 , Pages 1136-1146 ; 00207225 (ISSN) Sarvestani, A. S ; Mohammadi Shodja, H ; Delfani, M. R ; Sharif University of Technology
    To date, the existing theories pertinent to the determination of the scattered fields of an inhomogeneity have been limited to certain topological symmetries for which the method of wave-function expansion is widely used. In the literature the wave-function expansion method has also been employed to the case involving concentric coated fiber. An alternative approach is the dynamic equivalent inclusion method (DEIM) proposed by Fu and Mura [L.S. Fu, T. Mura, The determination of elastodynamic fields of an ellipsoidal inhomogeneity. ASME J. Appl. Mech. 50 (1983) 390-396.] who found the scattered field of a single spheroidal inhomogeneity. The pioneering work of Eshelby [J.D. Eshelby, The... 

    Dilepton Production and Synchrotron Radiation in a Magnetized Quark-Qluon Plasma

    , M.Sc. Thesis Sharif University of Technology Hosseini, Yasaman (Author) ; Sadooghi, Neda (Supervisor)
    Relativistic collisions of heavy ions lead to the formation of a new phase of matter called Quark-Gluon Plasma (QGP). In addition, strong magnetic fields generates in these collisions that its direction is perpendicular to the collision axis. This strong magnetic field affects the dynamics of particles in the QGP, and causes the appearance of the Landau levels in the particle’s energy spectrum. In this master thesis, we investigate the impact of the magnetic field on dilepton production and synchrotron radiation. We calculate the scattering probability of quark and anti-quark annihilation and dilepton creation by taking all Landau Levels into account. Then, by assuming that the magnetic... 

    The Scattering of Electro-Elastic Fields of an SH-Wave in a
    Piezoelectric Medium by an Eccentric Two-Phase Circular
    Piezoelectric Micro Sensor

    , M.Sc. Thesis Sharif University of Technology Jarfi, Hamid (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    This thesis presents an analytical solution for determination of the
    electro-elastic media subjected to an anti plane shear harmonic wave containing a multi-phase cylindrical fiber whose electro-elastic properties differ from those of the matrix. Both the matrix and the coated-fiber system are transversely isotropic piezoelectric materials with symmetry and poling axes parallel to the fiber axis. The coating can have variable thickness. The dynamic electro-mechanical equivalent inclusion method (DEMEIM) is presented and employed as an extension of dynamic equivalent inclusion method (DEIM) in order to take into account the electro-mechanical coupling. Accordingly, the coating-fiber... 

    Theoretical calculation of scattering efficiency of isotropic and anisotropic scattering particles employed in nanostructured solar cells

    , Article Journal of Optics (United Kingdom) ; Vol. 16, issue. 5 , 2014 ; ISSN: 20408978 Sasanpour, P ; Mohammadpour, R ; Sharif University of Technology
    Light scattering design in dye and quantum dot sensitized solar cells is one of the main concerns in enhancing their light harvesting efficiency, and also in improving their power conversion efficiency. Herein, we present a theoretical analysis to calculate the dependence of the light scattering efficiency in dye solar cells that have employed scattering agents with various sizes and morphologies incorporated in nanostructured photoanodes with different designs. Various isotropic and anisotropic nanostructures, including filled and hollow spheres, spherical voids, nanowires and hollow fibres in a size range of 100 nm to 900 nm, have been considered as scattering centres. The scattering... 

    Use of atomistic phonon dispersion and boltzmann transport formalism to study the thermal conductivity of narrow Si nanowires

    , Article Journal of Electronic Materials ; Volume 43, Issue 6 , 2014 , Pages 1829-1836 ; ISSN: 03615235 Karamitaheri, H ; Neophytou, N ; Kosina, H ; Sharif University of Technology
    We study the thermal properties of ultra-narrow silicon nanowires (NW) with diameters from 3 nm to 12 nm. We use the modified valence-force-field method for computation of phononic dispersion and the Boltzmann transport equation for calculation of phonon transport. Phonon dispersion in ultra-narrow 1D structures differs from dispersion in the bulk and dispersion in thicker NWs, which leads to different thermal properties. We show that as the diameter of the NW is reduced the density of long-wavelength phonons per cross section area increases, which increases their relative importance in carrying heat compared with the rest of the phonon spectrum. This effect, together with the fact that... 

    Scattering of an anti-plane shear wave by an embedded cylindrical micro-/nano-fiber within couple stress theory with micro inertia

    , Article International Journal of Solids and Structures ; Volume 58 , April , 2015 , Pages 73-90 ; 00207683 (ISSN) Shodja, H. M ; Goodarzi, A ; Delfani, M. R ; Haftbaradaran, H ; Sharif University of Technology
    Elsevier Ltd  2015
    The inadequacy of traditional theory of elasticity in describing such a phenomenon as dispersion associated to a propagating wave with wavelength comparable to the intrinsic length of the medium of interest is well-known. Moreover, under certain circumstances it is incapable of capturing all the propagating waves. A remedy to such dilemmas is the employment of the more accurate higher order continuum theories which give rise to the appearance of at least one new characteristic length in the formulation. The experimental evidences as well as lattice dynamic analysis suggest that, although higher order continuum theories result in some improvements, but cannot fully overcome the... 

    The scattering of P-waves by a piezoelectric particle with FGPM interfacial layers in a polymer matrix

    , Article International Journal of Solids and Structures ; Volume 47, Issue 18-19 , 2010 , Pages 2390-2397 ; 00207683 (ISSN) Kamali, M. T ; Shodja, H. M ; Sharif University of Technology
    Propagation of P-wave in an unbounded elastic polymer medium which contains a set of nested concentric spherical piezoelectric inhomogeneities is formulated. The polymer matrix is made of Epoxy and is isotropic; each phase of the inhomogeneity is made of a different piezoelectric material and is radially polarized and has spherical isotropy. Note that the individual phases are homogeneous, and all interfaces are perfectly bonded. The scattered displacement and electric potentials in the matrix are expressed in terms of spherical wave vector functions and Legendre functions, respectively. The transmitted displacement and electric potentials within each phase of the piezoelectric particle are... 

    The scattering of electro-elastic waves by a spherical piezoelectric particle in a polymer matrix

    , Article International Journal of Engineering Science ; Volume 44, Issue 10 , 2006 , Pages 633-649 ; 00207225 (ISSN) Kamali, M. T ; Shodja, H. M ; Sharif University of Technology
    This paper is devoted to the study of scattering of plane harmonic waves by a piezoelectric sphere with spherical isotropy embedded in an unbounded isotropic polymer matrix. The scattered displacement field and the electric potential in the matrix are expressed in terms of spherical vector wave functions and spherical harmonic functions, respectively. For the field points inside the inhomogeneity, new displacement functions are introduced. Expansion of the new displacement functions and the electric potential in terms of spherical harmonic functions, the equations of motion and electrostatic lead to four second order ordinary differential equations (odes), where three of them are coupled.... 

    Scattering of plane elastic waves by a multi-coated nanofiber with deformable interfaces

    , Article International Journal of Solids and Structures ; Volume 141-142 , 2018 , Pages 195-218 ; 00207683 (ISSN) Shodja, H. M ; Taheri Jam, M ; Sharif University of Technology
    Elsevier Ltd  2018
    The scattering of in-plane P- and SV-waves by a multi-coated circular nanofiber with deformable interfaces is of interest. To this end, in the present work, after introducing two kinds of interface momenta defined as the derivative of the interface excess kinetic energy with respect to the average and relative velocities at the interface, we extend the elastostatic theory of Gurtin et al. (1998) on deformable interfaces to the elastodynamic theory and derive the interface equations of motion using Hamilton principle. The effects of the generalized interface properties including the interface inertial parameters and interface stiffness towards stretch and slip on the dynamic stress... 

    Interface effects on the electromagnetic radiation emanating from an embedded piezoelectric nano-fiber incident upon by SH-waves

    , Article Wave Motion ; Volume 94 , April , 2020 Taheri Jam, M ; Shodja, H. M ; Sharif University of Technology
    Elsevier B.V  2020
    The multiphysics process of the electromagnetic (EM) radiation induced from an embedded nanofiber scatterer subjected to SH-waves is of interest. By discarding the commonly employed electroquasistatic approximation, the fully-coupled elastodynamics and Maxwell's equations have been solved simultaneously within the mathematical framework of piezoelectric surface elasticity theory. Certain subtleties regarding the introduced interface characteristic lengths that make the examination of the size effect on the EM radiated power, scattering cross section, fundamental resonance frequency, and distribution of the magnetic field possible will be discussed. The obtained results can be helpful for...