Search for dissertations about: "optical turbulence"

Showing result 1 - 5 of 32 swedish dissertations containing the words optical turbulence.

  1. 1. Optical Turbulence Characterization for Ground-Based Astronomy

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Susanna Hagelin; Anna Rutgersson; Elena Masciadri; Valentina Zitelli; [2010]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; site testing; atmospheric effects; turbulence; optical turbulence; applied meteorology; mesoscale models; NATURAL SCIENCES Earth sciences Atmosphere and hydrosphere sciences Meteorology; NATURVETENSKAP Geovetenskap Atmosfärs- och hydrosfärsvetenskap Meteorologi; NATURAL SCIENCES Physics Astronomy and astrophysics; NATURVETENSKAP Fysik Astronomi och astrofysik; Meteorologi; Meteorology;

    Abstract : The optical turbulence, which creates perturbations of the wavefronts coming from the stars, is caused by small-scale fluctuations in the index of refraction of the atmosphere and is a problem for astronomers because it limits the maximum resolution of the ground-based telescopes. One way of identifying the best sites to build astronomical observatories, where the influence of the optical turbulence is as small as possible, is to use the standard meteorological parameters to get a first idea of the potential of a site. READ MORE

  2. 2. Transport, Turbulence and Instabilities in Cosmic Magnetic Fields

    University dissertation from Uppsala : Acta Universitatis Upsaliensis

    Author : Giuseppe Di Bernardo; Göteborgs universitet.; Gothenburg University.; [2014]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Cosmic Rays; Interstella Medium; Galactic Magnetic Fields; Magnetohydrodynamics Turbulence; Accretion Discs;

    Abstract : This decade has seen a large number of space missions, which, alongside ground-based radio, optical and gamma-ray telescopes, have enabled a deep insight into the non-thermal astrophysical environments. Interstellar Medium (ISM), Supernovae Remnants (SNRs) and Black-Hole (BH) accretion discs (ADs) are only a few examples of natural habitat of interaction of relativistic particles and magnetic fields, largely mediated by the action of the turbulence. READ MORE

  3. 3. A Particle Image Velocimetry Study of Bubbly Gas-Liquid Flow

    University dissertation from Xiaoyun Tu, Division of Food Engineering, Department of Food Technology, Engineering and Nutrition

    Author : Xiaoyun Tu; [2004]
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; turbulent dispersion; Food and drink technology; Livsmedelsteknik; turbulence; Rushton turbine; stirred tank; slip velocity; bubbly gas liquid two-phase flow; coherent structure; CCD camera; PIV; POD;

    Abstract : The aim of this work is to build a framework that can be used for characterizing the bubbly gas liquid turbulent flow in the stirred bioreactor tank. To this end we have developed and modified techniques with which to measure the velocity of both dispersed gas and carrier liquid phases by the optical measurement technique, a 2-CCD camera Particle Image Velocimetry (PIV) system; and to characterize the turbulence by the wavelets tool, Proper Orthogonal Decomposition (POD). READ MORE

  4. 4. Radar Signatures of Auroral Plasma Instability

    University dissertation from Stockholm : KTH Royal Institute of Technology

    Author : Nicola Schlatter; Nickolay Ivchenko; Anja Stromme; [2015]
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Ionosphere; Particle Precipitation; Instability; Plasma Turbulence; Physics; Fysik;

    Abstract : Incoherent scatter radars are powerful ground based instruments for ionospheric measurements. By analysis of the Doppler shifted backscatter spectrum, containing the signature of electrostatic plasma waves, plasma bulk properties are estimated. READ MORE

  5. 5. Laser Sheet Imaging and Image Analysis for Combustion Research

    University dissertation from Stockholm : KTH Royal Institute of Technology

    Author : Rafeef Abu-Gharbieh; [2001]
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; non-linear diffusion filtering; optically dense sprays; curve evolution propagation; image sequence analysis; laser induced fluorescence; geodesic paths; level sets; LIF; optical density; spray characterization; flame propagation; laser; particle image velocimetry; spectroscopy; combustion engines; spray diagnostics; Mie scattering; flame fronts; laser attenuation; tracking; combustion diagnostics; curve matching; combustion; laser sheet imaging; PIV; time resolved imaging; segmentation;

    Abstract : This Thesis presents techniques that aim at exploiting the potential of image analysis and processing in order to solve problems of data reduction, interpolation, quantification, and interpretation within the field of experimental laser imaging of combustion processes. Combustion is the most important source of energy for power generation, heating, and transportation in the world today and its strong dominance is projected to continue in the foreseeable future. READ MORE