Sökning: "wave operator"

Visar resultat 1 - 5 av 46 avhandlingar innehållade orden wave operator.

  1. 1. Wave Propagation in Structural Elements - Direct and Inverse Problems in the Time Domain

    Författare :Peter Folkow; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; integro-differential equations; non-uniform beams; wave splitting; wave propagator; finite difference; Timoshenko beam; imbedding; Mindlin plate; inverse problem; viscoelastic damping; nonlinear rod; transient wave propagation; Green function;

    Sammanfattning : The subject of this thesis is direct and inverse wave propagation problems in structural elements. The considered structures are beams, plates and rods. The models for the beams and the plates are based on linear theory, while the rods are assumed to be nonlinear. The greater part of the work concerns the Timoshenko beam. LÄS MER

  3. 2. The Dirac Equation: Numerical and Asymptotic Analysis

    Författare :Hasan Almanasreh; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Dirac operator; eigenvalue problem; finite element method; spurious eigenvalues; Petrov-Galerkin; cubic Hermite basis functions; stability parameter; meshfree method; $hp$-cloud; intrinsic enrichment; G-convergence; $ Gamma$-convergence; scattering theory; identification; wave operator; stationary approach; Dirac operator;

    Sammanfattning : The thesis consists of three parts, although each part belongs to a specific subject area in mathematics, they are considered as subfields of the perturbation theory. The main objective of the presented work is the study of the Dirac operator; the first part concerns the treatment of the spurious eigenvalues in the computation of the discrete spectrum. LÄS MER

  4. 3. Numerical Methods for Wave Propagation : Analysis and Applications in Quantum Dynamics

    Författare :Emil Kieri; Sverker Holmgren; Vasile Gradinaru; Hans O. Karlsson; Tobias Jahnke; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; computational wave propagation; quantum dynamics; time-dependent Schrödinger equation; spectral methods; Gaussian beams; splitting methods; low-rank approximation; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : We study numerical methods for time-dependent partial differential equations describing wave propagation, primarily applied to problems in quantum dynamics governed by the time-dependent Schrödinger equation (TDSE). We consider both methods for spatial approximation and for time stepping. LÄS MER

  5. 4. Hydro-mechanical optimization of a wave energy converter

    Författare :Chisom Miriam Ekweoba; Andrej Savin; Halvar Gravråkmo; Uppsala universitet; []
    Nyckelord :Ballast optimization; analytical model; pitching wave energy converter; power absorption performance; wave energy converter; geometry optimization; genetic algorithm; floating platform; extended degrees of freedom; beam model; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

    Sammanfattning : Wave energy conversion technology has gained popularity due to its potential to be-come one of the most preferred energy sources. Its high energy density and low car-bon footprint have inspired the development of many wave energy converter (WEC) technologies, few of which have made their way to commercialisation, and many are progressing. LÄS MER

  7. 5. A Wave Expansion Method for Aeroacoustic Propagation

    Författare :Johan Hammar; Gunilla Efraimsson; Ciarán J. O'Reilly; Wim De Roeck; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound propagation; Sound generation; Aeroacoustics; Aerodynamics; Computational fluid dynamics; Computational aeroacoustics; Numerical methods; Lighthill; Curle; Ffowcs Williams and Hawkings; Frequency-domain propagation; Wave expansion method.; Vehicle and Maritime Engineering; Farkostteknik;

    Sammanfattning : Although it is possible to directly solve an entire flow-acoustics problem in one computation, this approach remains prohibitively large in terms of the computational resource required for most practical applications. Aeroacoustic problems are therefore usually split into two parts; one consisting of the source computation and one of the source propagation. LÄS MER