Sökning: "wave equation"

Visar resultat 6 - 10 av 208 avhandlingar innehållade orden wave equation.

  1. 6. High Order Cut Finite Element Methods for Wave Equations

    Författare :Simon Sticko; Gunilla Kreiss; Mats G. Larson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cut finite element; Wave equation; Immersed; Fictitious domain; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : This thesis considers wave propagation problems solved using finite element methods where a boundary or interface of the domain is not aligned with the computational mesh. Such methods are usually referred to as cut or immersed methods. LÄS MER

  3. 7. Shape Optimization for Acoustic Wave Propagation Problems

    Författare :Rajitha Udawalpola; Martin Berggren; Pekka Neittaanmäki; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; shape optimization; design optimization; acoustic wave propagation; Helmholtz equation; Boundary Element Method; Finite Element Method; inverse problems; adjoint method; gradient-based optimization; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : Boundary shape optimization is a technique to search for an optimal shape by modifying the boundary of a device with a pre-specified topology. We consider boundary shape optimization of acoustic horns in loudspeakers and brass wind instruments. LÄS MER

  4. 8. Waveguide Finite Elements Applied on a Car Tyre

    Författare :Carl-Magnus Nilsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wave equation; wave solution; waveguide; finite element; spectral finite element; tyre noise; tyre vibration; input power; shells; pre stress; fluid shell coupling; axi--symmetric;

    Sammanfattning : Structures acting as waveguides are quite common withexamples being, construction beams, fluid filled pipes, railsand extruded aluminium profiles. Curved structures like cartyres and pipe-bends may also be considered as waveguides. Wavesolutions in such structures may be found by a method calledthe Waveguide Finite Element Method or WFEM. LÄS MER

  5. 9. On weak and strong convergence of numerical approximations of stochastic partial differential equations

    Författare :Fredrik Lindgren; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Additive noise; Cahn-Hilliard-Cook equation; Error estimate; Finite element; Hyperbolic equation; Parabolic equation; Rational approximation; Stochastic partial differential equation; Strong convergence; Truncation; Wiener process; Weak convergence; Weak convergence;

    Sammanfattning : This thesis is concerned with numerical approximation of linear stochastic partial differential equations driven by additive noise. In the first part, we develop a framework for the analysis of weak convergence and within this framework we analyze the stochastic heat equation, the stochastic wave equation, and the linearized stochastic Cahn-Hilliard, or the linearized Cahn-Hilliard-Cook equation. LÄS MER

  7. 10. Wave interactions by Hamiltonian methods

    Författare :Krister Wiklund; Umeå universitet; []
    Nyckelord :Hamiltonian formulation; wave interaction; stability; variational principles;

    Sammanfattning : This thesis is devoted to the description of fluids and gases from a Hamiltonian point of view. The method we apply is a development of the theory invented by Hamilton (1805-1865). The original formulation is restricted to a certain family of dynamical variables; the canonical variables. LÄS MER