Sökning: "underwater acoustics"

Visar resultat 1 - 5 av 12 avhandlingar innehållade orden underwater acoustics.

  1. 1. 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

  3. 2. Underwater Positioning

    Författare :Patric Jansson; Lars Sjöberg; KTH; []
    Nyckelord :;

    Sammanfattning : The project underwater positioning was initiated by the Swedish National Road Administration (SNRA) in 1990. The aim of the project is to study positioning techniques and methods which can be used to position and locate man-made structures and features, especially engineering structures, piles for the foundation*laying of bridge pillars, in shallow water. LÄS MER

  4. 3. A Novel Signal Model and Estimation Method for Acoustic Doppler Current Meters

    Författare :Thomas L Lagö; Teknisk akustik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Doppler Profiler; Acoustic Doppler; Gaussian Backscattering Model; ADCM; ADCP; The Symmiktos Method; Estimation; Doppler; Current; MPCA.; Technological sciences; Teknik; Electromagnetism; optics; acoustics; Elektromagnetism; optik; akustik;

    Sammanfattning : This thesis deals with the process of estimating underwater current from the backscattering signal transmitted from an ultrasonic transducer. The narrowband sinusoidal burst signal is Doppler-shifted due to the current, and this information is converted into current. LÄS MER

  5. 4. Homogeneous models of anechoic rubber coatings

    Författare :Alex Cederholm; KTH; []
    Nyckelord :underwater acoustics anechoic reflection transmission ambient pressure genetic algorithm; inversion; underwater acoustics; anechoic; reflection; transmission; ambient pressure; genetic algorithm;

    Sammanfattning : .... LÄS MER

  7. 5. Design and implementation of a programmable, wideband sonar for sediment mapping

    Författare :Peter Jonsson; Teknisk geologi; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; centroid; programmable sonar; sediment mapping; underwater acoustics; hydroacoustics; echosounder;

    Sammanfattning : To be able to explore different signal types and processing techniques, apt for sediment mapping, programmable, fully digital profiling systems has been built and tested. The systema are designed to be deployed also at small water depths from small boats, without special handling equipment. LÄS MER