Sökning: "Sound propagation"

Visar resultat 1 - 5 av 88 avhandlingar innehållade orden Sound propagation.

  1. 1. 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. 2. 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

  4. 3. Wind Turbine Sound Propagation in the Atmospheric Boundary Layer

    Författare :Olof Öhlund; Conny Larsson; Anna Sjöblom; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Wind turbine sound; atmospheric effects; outdoor sound propagation; refraction;

    Sammanfattning : Wind turbines have grown both in size and number in the past decades. The taller turbines has made it possible to place them in forest areas which is fortunate for a country like Sweden with lots of forest. An issue with wind turbines is the sound they produce. The sound mainly comes from the rotor blades when they pass through the air. LÄS MER

  5. 4. Sound propagation around off-shore wind turbines

    Författare :Lisa Johansson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind turbine noise; off-shore wind powe; long-rage sound propagation; parabolic equation; scattering; water waves; Building engineering; Byggnadsteknik;

    Sammanfattning : Low-frequency, long-range sound propagation over a seasurface has been calculated using a wide-angel Cranck-NicholsonParabolic Equation method. The model is developed toinvestigate noise from off-shore wind turbines. Thecalculations are made using normal meteorological conditions ofthe Baltic Sea. LÄS MER

  7. 5. Wind Turbine Sound in Cold Climates

    Författare :Kristina Conrady; Anna Rutgersson; Karl Bolin; Sabine von Hünerbein; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; atmospheric acoustics; wind turbine sound; outdoor sound propagation; cold climates; Meteorology; Meteorologi;

    Sammanfattning : The increase in the number of wind turbines (WTs) in populated areas in cold climates increases the number of people potentially being affected by WT sound. Outdoor sound propagation is strongly dependent on meteorological conditions, however, limitations in the knowledge exist regarding the implications of meteorological conditions in cold climates. LÄS MER