Search for dissertations about: "frequency transform"

Showing result 1 - 5 of 105 swedish dissertations containing the words frequency transform.

  2. 1. Optical Frequency Comb Fourier Transform Spectroscopy

    Author : Alexandra C. Johansson; Aleksandra Foltynowicz; Ove Axner; Jürgen Röpcke; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Optical frequency comb spectroscopy; Fourier transform; molecular absorption dispersion; fysik; Physics;

    Abstract : Fourier transform spectroscopy (FTS) based on optical frequency combs is an excellent spectroscopic tool as it provides broadband molecular spectra with high spectral resolution and an absolutely calibrated frequency scale. Moreover, the equidistant comb mode structure enables efficient coupling of the comb to enhancement cavities, yielding high detection sensitivity. READ MORE

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

    Author : Amir Khodabakhsh; Aleksandra Foltynowicz; Ove Axner; Frans Harren; Umeå universitet; []
    Keywords : 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. 3. The Texture-Transform : An Operator for Texture Detection and Discrimination

    Author : Alireza Tavakoli Targhi; Jan-Olof Eklundh; Arnold Smeulders; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Computer science; Datalogi;

    Abstract : In this thesis we present contributions related to texture detection and discrimination to be used for analyzing real world images. Many computer vision applications can benefit from a fast and low dimensional texture descriptor. READ MORE

  6. 4. Precision molecular spectroscopy in the near- and mid-infrared using frequency comb-based Fourier transform spectrometers

    Author : Adrian Hjältén; Aleksandra Foltynowicz; Ove Axner; Adam Fleisher; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; optical frequency comb; molecular spectroscopy; Fourier transform spectrometer; high resolution; mid-infrared; line list; double-resonance spectroscopy; difference frequency generation; fysik; Physics;

    Abstract : Absorption spectroscopy is a powerful scientific tool for non-invasive and remote sensing applications ranging from atmospheric monitoring to astrophysics. In spectroscopic detection schemes it is necessary to have spectral models for any molecular species to be detected or quantified. READ MORE

  7. 5. Discrete Stochastic Time-Frequency Analysis and Cepstrum Estimation

    Author : Johan Sandberg; Matematisk statistik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; ambiguity domain; time-frequency analysis; time-frequency representations; covariance function; non-stationary random processes; Speaker recognition; MFCC; cepstrum;

    Abstract : The theory of stochastic time-frequency analysis of non-stationary random processes has mostly been developed for processes in continuous time. In practice however, random processes are observed, processed, and interpreted at a finite set of time points. READ MORE