Sökning: "time-domain"

Visar resultat 1 - 5 av 298 avhandlingar innehållade ordet time-domain.

  1. 1. Time Domain Boundary Element Methods for Acoustic Scattering

    Författare :Georgios Natsiopoulos; [2008]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; time domain; curved surface; room acoustics; boss model; boundary element method; regularization; transient; Hermite interpolation; hypersingular; acoustic scattering; vector potential;

    Sammanfattning : In room acoustics, numerical computation of scattering phenomena is an important subject, since it is needed to accurately predict the influence of reflectors, the audience, balconies, etc, on the perceived acoustic quality of auditoria. The large physical volumes of auditoria and the wide frequency content of music and speech, together with the complicated geometries involved however, makes predictions in room acoustics a challenging task from a computational point of view. LÄS MER

  2. 2. Hybrid Solvers for the Maxwell Equations in Time-Domain

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Fredrik Edelvik; Uppsala universitet.; Uppsala universitet.; [2002]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Maxwell s equations; time-domain; finite volume methods; finite element methods; hybrid solver; dispersive materials; thin wires; Scientific Computing; Beräkningsvetenskap;

    Sammanfattning : The most commonly used method for the time-domain Maxwell equations is the Finite-Difference Time-Domain method (FDTD). This is an explicit, second-order accurate method, which is used on a staggered Cartesian grid. The main drawback with the FDTD method is its inability to accurately model curved objects and small geometrical features. LÄS MER

  3. 3. Efficient time-domain modelling suitable for optimising thermoacoustic devices

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Stig Kleiven; [2010]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; finite-difference; thermoacoustics; time domain; optimisation; equivalent source method; active control;

    Sammanfattning : Thermoacoustic heat pumps use acoustic work to transfer heat from cold to hot temperatures. Such devices benefit from being environmentally friendly, robust and simple. However, in practice these devices have too low efficiency and power compared to their conventional counterparts. LÄS MER

  4. 4. Time-domain modelling of high-frequency wheel/rail interaction

    Detta är en avhandling från Gothenburg : Chalmers tekniska högskola

    Författare :Astrid Pieringer; [2011]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wheel rail interaction; railway noise; roughness; time domain; frictional instability; discrete irregularities; transient contact; non-Hertzian contact;

    Sammanfattning : The interaction between wheel and rail is the predominant source of noise emission from railway operations in a wide range of conventional speeds. On the one hand, this wheel/rail noise concerns rolling noise and impact noise caused by the vertical interaction excited by roughness and discrete irregularities of the wheel/rail running surfaces, respectively. LÄS MER

  5. 5. Time-Domain Methods for the Maxwell Equations

    Detta är en avhandling från Stockholm : Numerisk analys och datalogi

    Författare :Ulf Andersson; KTH.; [2001]
    Nyckelord :Computational Electromagnetics; time-domain methods;

    Sammanfattning : .... LÄS MER