Search for dissertations about: "acoustic wave equation"
Showing result 21 - 25 of 28 swedish dissertations containing the words acoustic wave equation.
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21. Waves and instabilities in quantum plasmas
Abstract : The study of waves and instabilities in quantum plasmas is of fundamental importance for understanding collective interactions in superdense astrophysical objects, in high intense laser-plasma/solid-matter interactions, in microelectronic devices and metallic nanostructures. In dense quantum plasmas, there are new pressure laws associated with the Fermi-Dirac distribution functions and new quantum forces associated with the quantum Bohm potential and the Bohr magnetization involving electron ½ spin. READ MORE
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22. Approximations of Integral Equations for WaveScattering
Abstract : Wave scattering is the phenomenon in which a wave field interacts with physical objects. An incoming wave is scattered at the surface of the object and a scattered wave is produced. Common practical cases are acoustic, electromagnetic and elastic wave scattering. READ MORE
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23. Adaptive finite element/difference methods for time-dependent inverse scattering problems
Abstract : In this thesis we develop adaptive hybrid finite element/difference methods for inverse time-domain acoustic and elastic scattering, where we seek to find the location and form of a (small) unknown object inside a large homogeneous body from measured wave-reflection data. We formulate the inverse problem as an optimal control problem, where we seek to reconstruct unknown material coefficients with best least squares wave fit to data. READ MORE
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24. A Linearized Navier-Stokes Equations Methodology for Aeroacoustic and Thermoacoustic Simulations
Abstract : Aeroengine noise is one of the dominating noise sources in today’s aircraft. Reduction of the aeroengine noise is related to multiphysics phenomena, and that is subject to different mechanisms, e.g., the coupling between turbulence, flame and sound waves. READ MORE
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25. Sound Insulation at Low Frequencies
Abstract : The airborne sound transmission through building partitions at low frequencies was studied. The definition of the sound reduction index as a measure of sound insulation has been examined by means of extensive numerical simulations in 3-D domains. The simulations were based on the wave theoretical acoustics. READ MORE