Sökning: "numerical propagation"

Visar resultat 11 - 15 av 283 avhandlingar innehållade orden numerical propagation.

  1. 11. Transient electromagnetic pulse propagation in temporally dispersive materials

    Författare :Igor Egorov; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Green functions; direct scattering; time domain; wave propagation; bi-gyrotropic; chiral; bi-isotropic; Forerunner; precursor; Green dyadics; Electronics and Electrical technology; Elektronik och elektroteknik;

    Sammanfattning : This thesis treats the problem of transient electromagnetic pulse propagation in temporally dispersive media. The analysis is performed using time-domain techniques. In particular, the dispersive wave splitting which decouples the Maxwell equations both in vacuum and inside the medium is utilized. LÄS MER

  3. 12. Numerical modelling of sound propagation to closed urban courtyards

    Författare :Maarten Hornikx; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; courtyard; urban noise abatement schemes; pseudospectral; road traffic noise; equivalent sources method; scale model study; urban canyon;

    Sammanfattning : Because modern urban environments suffer from excessive levels of road traffic noise, access to closed courtyards is essential in order to offer urban sound environments of high quality with regard to health and perceived sound. To reach this quality, which is described by the quiet side definition, the 24-hour equivalent noise level should be below 45 dB(A). LÄS MER

  4. 13. Numerical Methods for Darcy Flow Problems with Rough and Uncertain Data

    Författare :Fredrik Hellman; Axel Målqvist; Auli Niemi; Fritjof Fagerlund; Robert Scheichl; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; numerical homogenization; multiscale methods; rough coefficients; high contrast coefficients; mixed finite elements; cdf estimation; multilevel Monte Carlo methods; Darcy flow problems; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Sammanfattning : We address two computational challenges for numerical simulations of Darcy flow problems: rough and uncertain data. The rapidly varying and possibly high contrast permeability coefficient for the pressure equation in Darcy flow problems generally leads to irregular solutions, which in turn make standard solution techniques perform poorly. LÄS MER

  5. 14. Theoretical and numerical studies of sound propagation in low-Mach-number duct flows

    Författare :Chenyang Weng; Mats Åbom; Susann Boij; Ardeshir Hanifi; Anurag Agarwal; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Acoustic wave absorption; Acoustic wave propagation; Boundary layer turbulence; DNS; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : When sound waves propagate in a duct in the presence of turbulent flow, turbulent mixing can cause attenuation of the sound waves extra to that caused by the viscothermal effects. Experiments show that compared to the viscothermal effects, this turbulent absorption becomes the dominant contribution to the sound attenuation at sufficiently low frequencies. LÄS MER

  7. 15. Impact loading on concrete structures : a constitutive modelling, finite element analysis, and experimental study of nonlinear wave propagation

    Författare :Larsgunnar Nilsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; experimental study; numerical procedures; plasticity; Nonlinear wave propagation; reinforced concrete; brittle failure; contact-impact; visco plasticity;

    Sammanfattning : .... LÄS MER