Avancerad sökning

Hittade 5 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Dicke narrowing and speed-dependent effects in dispersion signals : Influence on assessment of concentration and spectral parameters by noise-immune cavity-enhanced optical heterodyne molecular spectrometry

   Författare :Junyang Wang; Ove Axner; Livio Gianfrani; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Dicke narrowing; Speed-dependent effects; Dispersion signals; Noise-immune cavity-enhanced optical heterodyne molecular spectrometry NICE-OHMS ; accuracy;

   Sammanfattning : Laser spectroscopic techniques have, during the last decades, demonstrated an extraordinary capability for sensitive detection of molecular constituents in gas phase. Since spectra from such techniques constitute unique and characteristic signatures for each type of species, these techniques enable investigations of molecular structures as well as detection of the presence of species in a gas mixture. LÄS MER

3. 2. 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

4. 3. Aerosol deposition to coastal forests: a wind tunnel approach

   Författare :Ausra Reinap; Bo L.B. Wiman; Birgitta Svenningsson; Bo Bergbäck; Lise Lotte Sørensen; Linnéuniversitetet; []
   Nyckelord :NaCl aerosol; dry deposition; climate change; coastal-zone forest; Quercus robur; wind tunnel; edge effect; NATURAL SCIENCES; NATURVETENSKAP; Miljövetenskap; Environmental Science;

   Sammanfattning : Aerodynamically rough surfaces of forests provide for efficient air/ canopy exchange of mass, heat and momentum. In that context, the effects of forest edges come into focus, and therefore, coastal-zone forests constitute aparticular concern. LÄS MER

5. 4. Wave Loads and Peak Forces on Moored Wave Energy Devices in Tsunamis and Extreme Waves

   Författare :Linnea Sjökvist; Malin Göteman; Mats Leijon; Peter Stansby; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; OpenFOAM; CFD; Wave power; Tsunami waves; Extreme waves; Offshore; Engineering Science with specialization in Science of Electricity; Teknisk fysik med inriktning mot elektricitetslära;

   Sammanfattning : Surface gravity waves carry enormous amounts of energy over our oceans, and if their energy could be harvested to generate electricity, it could make a significant contribution to the worlds power demand. But the survivability of wave energy devices in harsh operating conditions has proven challenging, and for wave energy to be a possibility, peak forces during storms and extreme waves must be studied and the devices behaviour understood. LÄS MER

7. 5. Cavity enhanced optical sensing

   Författare :Isak Silander; Ove Axner; Aleksandra Foltynowicz; Jong Chow; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optical resonators; Fiber Laser; Parametric oscillators; Optical frequency comb; Infrared; Spectroscopy heterodyne; Spectroscopy molecular; Absorption; Dispersion; Lineshapes; Optical standards and testing; Refractivety measurements;

   Sammanfattning : An optical cavity comprises a set of mirrors between which light can be reflected a number of times. The selectivity and stability of optical cavities make them extremely useful as frequency references or discri­mi­nators. LÄS MER