Sökning: "wave equation"

Visar resultat 31 - 35 av 208 avhandlingar innehållade orden wave equation.

  1. 31. Elastic wave scattering from corrugated surfaces in anisotropic media

    Författare :Tatiana Krasnova; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; corrugated surface; perturbation approach; scattering; anisotropy; ultrasonic waves; null field approach; integral equation; Green s function;

    Sammanfattning : .... LÄS MER

  3. 32. Fourth order symmetric finite difference schemes for the wave equation

    Författare :Abraham Zemui; Bertil Gustafsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Numerical Analysis; Numerisk analys;

    Sammanfattning : The solution of the acoustic wave equation in one space dimension is studied. The PDE is discretized using finite element approximation. A cubic piecewise Lagrange polynomial is used as basis. Consistent finite element and lumped mass schemes are obtained. LÄS MER

  4. 33. Numerical Vlasov–Maxwell Modelling of Space Plasma

    Författare :Bengt Eliasson; Bertil Gustafsson; Bo Thidé; Anders Bondeson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Vlasov equation; Maxwell equation; Fourier method; outflow boundary; domain decomposition; Numerical Analysis; Numerisk analys;

    Sammanfattning : The Vlasov equation describes the evolution of the distribution function of particles in phase space (x,v), where the particles interact with long-range forces, but where shortrange "collisional" forces are neglected. A space plasma consists of low-mass electrically charged particles, and therefore the most important long-range forces acting in the plasma are the Lorentz forces created by electromagnetic fields. LÄS MER

  5. 34. Numerical methods for Sylvester-type matrix equations and nonlinear eigenvalue problems

    Författare :Emil Ringh; Elias Jarlebring; Johan Karlsson; Per Enqvist; Daniel Kressner; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matrix equations; Lyapunov equation; Sylvester equation; nonlinear eigenvalue problems; two-parameter eigenvalue problems; Krylov methods; iterative methods; preconditioning; projection methods; Matrisekvationer; Lyapunovekvationen; Sylvesterekvationen; ickelinjära egenvärdesproblem; två-parameters egenvärdesproblem; Krylovmetoder; iterativa metoder; förkonditionering; projektionsmetoder; Tillämpad matematik och beräkningsmatematik; Applied and Computational Mathematics; Optimization and Systems Theory; Optimeringslära och systemteori; Numerical Analysis; Numerisk analys;

    Sammanfattning : Linear matrix equations and nonlinear eigenvalue problems (NEP) appear in a wide variety of applications in science and engineering. Important special cases of the former are the Lyapunov equation, the Sylvester equation, and their respective generalizations. These appear, e.g. LÄS MER

  7. 35. Towards higher order immersed finite elements for the wave equation

    Författare :Simon Sticko; Gunilla Kreiss; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : We consider solving the scalar wave equation using immersed finite elements. Such a method might be useful, for instance, in scattering problems when the geometry of the domain is not known a priori. For hyperbolic problems, the amount of computational work per dispersion error is generally lower when using higher order methods. LÄS MER