Search for dissertations about: "cavity enhancement"

Showing result 1 - 5 of 19 swedish dissertations containing the words cavity enhancement.

  1. 1. Fiber-laser-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry

    Author : Aleksandra Foltynowicz; Ove Axner; Weidong Chen; Umeå universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; absorption spectrometry; frequency modulation; cavity enhancement; NICE-OHMS; Laser frequency stabilization; fiber laser; Fabry-Perot cavities; sub-Doppler spectroscopy; trace gas detection; Physics; Fysik; Molecular physics; Molekylfysik; fysik; Physics;

    Abstract : Noise-immune cavity-enhanced optical heterodyne molecular spectro-metry (NICE-OHMS) is one of the most sensitive laser-based absorption techniques. The high sensitivity of NICE-OHMS is obtained by a unique combination of cavity enhancement (for increased interaction length with a sample) with frequency modulation spectrometry (for reduction of noise). READ MORE

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

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

    Abstract : 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. READ MORE

  3. 3. Investigations of Heat Transfer and Fluid Flow in the Pocket Region of a Gas Turbine Engine and Cooling of a Turbine Blade

    Author : Jian Liu; Värmeöverföring; []
    Keywords : pocket cavity; symmetric vane; Liquid Crystal Thermography; truncated ribs; staggered arrangement; perforated ribs; secondary flows; endwall film cooling; leading edge; turbine vane; coolant coverage;

    Abstract : In the present work, heat transfer within gas turbine applications are investigated bothexperimentally and numerically. The main content concerns heat transfer and fluidflow over the pocket region and cooling of a turbine blade. READ MORE

  4. 4. Fourier transform and Vernier spectroscopy using optical frequency combs

    Author : Amir Khodabakhsh; Aleksandra Foltynowicz; Ove Axner; Frans Harren; Umeå universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; optical frequency comb spectroscopy; molecular absorption; resonant cavity; Fourier transform spectroscopy; Vernier spectroscopy; fysik; Physics;

    Abstract : Optical frequency comb spectroscopy (OFCS) combines two previously exclusive features, i.e., wide optical bandwidth and high spectral resolution, enabling precise measurements of entire molecular bands and simultaneous monitoring of multiple gas species in a short measurement time. READ MORE

  5. 5. Bi-based high Tc superconductors and enhancement of critical current density

    Author : Shi-ju Guo; Luleå tekniska universitet; []
    Keywords : ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material Mechanics; Materialmekanik;

    Abstract : Basic bulk high temperature superconductors in the Bi-Sr-Ca-Cu-O system and the BiPb-Sr-Ca-Cu-O system were prepared through the solid state reaction route and the coprecipitation method. The formation of 110 K phase promoted by partial Pb substitution for Bi was studied. Effects of heat treatment on 110K phase formation were studied. READ MORE