Sökning: "propagation"

Visar resultat 11 - 15 av 1242 avhandlingar innehållade ordet propagation.

  1. 11. Sound propagation from sustainable ground vehicles : from aeroacoustic sources to urban noise

    Författare :Nicolas Pignier; Ciarán O'Reilly; Susann Boij; Gwenael Gabard; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; sound propagation; sound generation; ground vehicle; aeroacoustics; aerodynamics; Kirchhoff approximation; detached eddy simulation; Ffowcs Williams and Hawkings; ljudutberdning; ljudalstring; markfordon; aeroakustik; aerodynamik; Kirchhoff approximation; detached eddy simulation; Ffowcs Williams and Hawkings; Vehicle and Maritime Engineering; Farkostteknik; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : Transportation is the main source of environmental noise in Europe, with an estimated 125 million people affected by excessive noise levels from road traffic, causing a burden of noise related diseases and having a substantial economic impact on society. In order to reduce exposure to high levels of traffic noise, two approaches are the topic of extensive research: preventing sound from propagating from roads and railways using for example noise barriers, and reducing the sources of noise themselves. LÄS MER

  3. 12. 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

  4. 13. Wind Turbine Noise and Natural Sounds : Masking, Propagation and Modeling

    Författare :Karl Bolin; Mats Åbom; Jens Forssén; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Wind turbine noise; models of natural sound sources; masking; Acoustics; Akustik;

    Sammanfattning : Wind turbines are an environmentally friendly and sustainable power source. Unfortunately, the noise impact can cause deteriorated living conditions for nearby residents. The audibility of wind turbine sound is influenced by ambient sound. This thesis deals with some aspects of noise from wind turbines. LÄS MER

  5. 14. Radio waves in the ionosphere : Propagation, generation and detection

    Författare :Tobia Carozzi; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space Physics; rymdfysik;

    Sammanfattning : We discuss various topics concerning the propagation, generation, and detec-tionof high-frequency (HF) radio waves in the Earth's ionosphere. With re-gardsto propagation, we derive a full wave Hamiltonian and a polarization evo-lutionequation for electromagnetic waves in a cold, stratified magnetoplasma. LÄS MER

  7. 15. Wave propagation and astromolecules

    Författare :Åke Hjalmarsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : .... LÄS MER