Sökning: "acoustics"

Visar resultat 11 - 15 av 1039 avhandlingar innehållade ordet acoustics.

  1. 11. Acoustical properties of earplugs

    Författare :Per Hiselius; Teknisk akustik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Maskinteknik; hydraulik; vakuumteknik; vibrationer; akustik; vibration and acoustic engineering; vacuum technology; hydraulics; Mechanical engineering; acoustic modelling; objective measurement; insertion loss; earplugs; HPE; HPD; hearing protectors; Two-Port; Four-Pole; attenuation; electro acoustics; acoustics;

    Sammanfattning : In this study an experimental setup for measurements of high impedance objects in ducts, yielding the acoustical Two-Port properties of the object, is applied to earplugs. A frequently used experimental setup for measuring objective acoustical properties of earplugs is that of artificial ears. Great effort is spent on duplicating the human ear. LÄS MER

  3. 12. Physical modelling of acoustic shallow-water communication channels

    Författare :Elin Svensson; Ilkka Karasalo; Finn Jensen; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; underwater acoustics; hydroacoustics; time variability; ray tracing; Gaussian beam summation; sound propagation models; shallow water; waveguides; caustics; underwater communication; undervattensakustik; hydroakustik; tidsvariabilitet; strålgång; gaussisk strålsummation; ljudutbredningsmodeller; grunt vatten; vågledare; kaustikor; undervattenskommunikation; Acoustics; Akustik;

    Sammanfattning : Akustiska kanaler för undervattenskommunikation är flervägskanaler där ljudet reflekteras från havets yta och botten och bryts vid ljudhastighetsförändringar. I grunt vatten är impulssvaret långt jämfört med symbolernas tidslängd i ett utskickat meddelande. LÄS MER

  4. 13. Operating conditions impact on flow and acoustics in turbocharger compressors

    Författare :Emelie Trigell; Mihai Mihaescu; Mats Åbom; Lisa Prahl Wittberg; Damian Vogt; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbocharger; compressor; LES; surge; rotating stall; flow instabilities; inlet recirculation; aeroacoustics; acoustics; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Fluid machines are an integral part in energy conversion with applications from pumps, fans, propellers, compressors and turbines. In the automotive industry, turbochargers are commonly employed to counteract the effect of engine downsizing. LÄS MER

  5. 14. Uncovering Ocean Mixing near Rough Bathymetry : Using Broadband Acoustics

    Författare :Julia C. Muchowski; Christian Stranne; Martin Jakobsson; Lars Umlauf; Lars Arneborg; Fer Ilker; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ocean mixing; diapycnal mixing; broadband acoustics; turbulence microstructure; rough bathymetry; stratified flow over obstacles; observations of turbulent mixing; Baltic Sea research; maringeologi; Marine Geology;

    Sammanfattning : Ocean mixing related to rough bathymetry is highly dynamic and exhibits large spatial and temporal variability. Therefore, established in-situ methods as well as numerical models often lack the resolution to capture this type of mixing. In this thesis, acoustics are used to observe, map and quantify stratified mixing at unprecedented resolution. LÄS MER

  7. 15. The material distribution method : analysis and acoustics applications

    Författare :Fotios Kasolis; Martin Berggren; Volker Schulz; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material distribution method; fictitious domain method; finite element method; Helmholtz equation; linear elasticity; shape optimization; topology optimization;

    Sammanfattning : For the purpose of numerically simulating continuum mechanical structures, different types of material may be represented by the extreme values {,1}, where 0.... LÄS MER