Sökning: "optical turbulence"

Visar resultat 1 - 5 av 33 avhandlingar innehållade orden optical turbulence.

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

   Författare :Susanna Hagelin; Anna Rutgersson; Elena Masciadri; Valentina Zitelli; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; site testing; atmospheric effects; turbulence; optical turbulence; applied meteorology; mesoscale models; Meteorology; Meteorologi; Astronomy and astrophysics; Astronomi och astrofysik; Meteorologi; Meteorology;

   Sammanfattning : 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. LÄS MER

3. 2. Laser Diagnostics in Reacting Flows

   Författare :Panagiota Stamatoglou; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; planar laser-induced fluorescence PLIF ; gliding arc GA discharge; Plasma Discharges; Turbulence; Combustion Engines; Spectroscopy; high-speed camera HSC ; Burst System; OH-LIF; optical parametric oscillator OPO ; Fysicumarkivet A:2023:Stamatoglou;

   Sammanfattning : Burst-mode laser systems have widely been employed in diagnostics for both reactive and non-reactive flows. Unlike the continuous pulse lasers, burst-mode lasers generate pulses in bursts lasting up to 100 ms, capable to deliver high energies up to Joules per pulse. LÄS MER

4. 3. Transport, Turbulence and Instabilities in Cosmic Magnetic Fields

   Författare :Giuseppe Di Bernardo; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cosmic Rays; Interstella Medium; Galactic Magnetic Fields; Magnetohydrodynamics Turbulence; Accretion Discs;

   Sammanfattning : 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. LÄS MER

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

   Författare :Xiaoyun Tu; Livsmedelsteknik; []
   Nyckelord :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;

   Sammanfattning : 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). LÄS MER

7. 5. Radar Signatures of Auroral Plasma Instability

   Författare :Nicola Schlatter; Nickolay Ivchenko; Anja Stromme; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ionosphere; Particle Precipitation; Instability; Plasma Turbulence; Fysik; Physics;

   Sammanfattning : 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. LÄS MER