Sökning: "Doppler Profiler"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden Doppler Profiler.

  1. 1. 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

  3. 2. Modeling rating curves from close-range remote sensing data : Application of laser and acoustic ranging instruments for capturing stream channel topography

    Författare :Norris Lam; Steve W. Lyon; Jason W. Kean; Ida Westerberg; Helle Skånes; James Brasington; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; laser scanning; acoustic Doppler current profiler; hydraulic modeling; rating curves; Sweden; Physical Geography; naturgeografi;

    Sammanfattning : A rating curve provides a functional relationship between water height (i.e. stage) and discharge at a specified cross-section in a river. Used in combination with a time series of stage, rating curves become one of the central components for generating continuous records of streamflow. LÄS MER

  4. 3. Simulations and measurements of free surface flow in regulated rivers

    Författare :Anders G. Andersson; Mats Billstein; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Strömningslära; Fluid Mechanics;

    Sammanfattning : Open channel flow near hydropower stations is of interest for both engineering and environmental applications. In this research project Computational Fluid Dynamics simulations of free surface flow in regulated rivers were applied with both fish migration and validation of numerical simulations in focus. LÄS MER

  5. 4. Modelling flow with free and rough surfaces in the vicinity of hydropower plants

    Författare :Anders G. Andersson; Nils Rüther; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Strömningslära; Fluid Mechanics;

    Sammanfattning : Flow with free and rough surfaces near hydropower stations is of interest for both engineering and environmental applications. Here, Computational Fluid Dynamics simulations of free surface flow and flow over rough surfaces in regulated rivers were performed in applications such fish migration, spillway design and flow over rough surfaces as in hydropower tunnels or natural channels. LÄS MER

  7. 5. Further development of NICE-OHMS : – an ultra-sensitive frequency-modulated cavity-enhanced laser-based spectroscopic
 technique for detection of molecules in gas phase

    Författare :Patrick Ehlers; Ove Axner; Joakim Bood; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NICE-OHMS; Frequency Modulation; Cavity Enhancement; Molecular Spectroscopy; fysik; Physics;

    Sammanfattning : Noise-immune cavity-enhanced optical heterodyne molecular spectroscopy, NICE-OHMS, is a laser-based spectroscopic detection technique that comprises the concepts of frequency modulation (FM, for reduction of 1/f-noise by detecting the signal at a high frequency) and cavity enhancement (CE, for a prolongation of the optical path length) in a unique way. Properly designed, this gives the technique an intrinsic immunity against the frequency-to-noise conversion that limits many other types of CE techniques. LÄS MER