Sökning: "frequency spectra"

Visar resultat 1 - 5 av 155 avhandlingar innehållade orden frequency spectra.

  1. 1. Sparse Modeling of Grouped Line Spectra

    Författare :Ted Kronvall; Statistical Signal Processing Group; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; line spectra; parameter estimation; convex optimization; group-sparsity; block-sparsity; dictionary learning; ADMM; adaptive penalty; total variation; multi-pitch estimation; chroma; audio processing; TDOA; near-field localization; amplitude modulation;

    Sammanfattning : This licentiate thesis focuses on clustered parametric models for estimation of line spectra, when the spectral content of a signal source is assumed to exhibit some form of grouping. Different from previous parametric approaches, which generally require explicit knowledge of the model orders, this thesis exploits sparse modeling, where the orders are implicitly chosen. LÄS MER

  3. 2. Optical Frequency Comb Fourier Transform Spectroscopy

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

    Sammanfattning : 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. LÄS MER

  4. 3. Low Frequency Impact Sound in Timber Buildings : Transmission Measurements and Simulations

    Författare :Jörgen Olsson; Andreas Linderholt; Börje Nilsson; Carl Hopkins; Linnéuniversitetet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Timber floors; FE-simulations; Light weight floors; Frequency response functions; Building acoustics; Byggteknik; Civil engineering;

    Sammanfattning : An increased share of multi-story buildings that have timber structures entails potential in terms of increased sustainability as well as human-friendly manufacturing and habitation. Timber buildings taller than two stories were prohibited in Europe until the 1990s due to fire regulations. In 1994, this prohibition was removed in Sweden. LÄS MER

  5. 4. Frequency combs on chip for interferometry applications

    Författare :Israel Rebolledo Salgado; Martin Zelan; Victor Torres-Company; Karsten Rottwitt; RISE; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; optical frequency combs; microcombs; pulses; nonlinear optics; interferometry; integrated photonics; spectroscopy;

    Sammanfattning : Optical frequency combs have revolutionized the field of laser spectroscopy. A frequency comb is a type of laser that generates an array of equally spaced coherent laser lines. Indeed, the outstanding performance of frequency combs in terms of bandwidth and stability is readily attainable in bench-top systems. LÄS MER

  7. 5. Tracing selection and adaptation along an environmental gradient in Populus tremula

    Författare :David Hall; Pär Ingvarsson; Thomas Bataillon; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Local adaptation; Selection; genetic differentiation; QST; FST; Association study; frequency spectra; recurrent hitchhiking; selective sweep; Tree; Populus; natural selection; quantitative genetics; Terrestrial ecology; Terrestrisk ekologi; Population Biology; populationsbiologi; genetik; Genetics;

    Sammanfattning : The distribution of the expressed genotype is moved around in the population over time byevolution. Natural selection is one of the forces that act on the phenotype to change the patterns ofnucleotide variation underlying those distributions. LÄS MER