Sökning: "spectral line"

Visar resultat 1 - 5 av 177 avhandlingar innehållade orden spectral line.

  1. 1. Wind turbine simulations using spectral elements

    Författare :Elektra Kleusberg; Dan Henningson; Philipp Schlatter; Stefan Ivanell; Johan Meyers; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind turbine; wakes; wake interaction; computational fluid dynamics; actuator line method; spectral elements; free-stream turbulence; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : Understanding the flow around wind turbines is a highly relevant research question due to the increased interest in harvesting energy from renewable sources. This thesis approaches the topic by means of numerical simulations using the actuator line method and the incompressible Navier–Stokes equations in the spectral element code Nek5000. LÄS MER

  3. 2. Estimation and detection of transmission line characteristics in the copper access network

    Författare :Fredrik Lindqvist; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Digital subscriber line; DSL; line qualification; twisted-pair line; copper access network; cable modeling; crosstalk channel estimation; estimation; detection;

    Sammanfattning : The copper access-network operators face the challenge of developing and maintaining cost-effective digital subscriber line (DSL) services that are competitive to other broadband access technologies. The way forward is dictated by the demand of ever increasing data rates on the twisted-pair copper lines. LÄS MER

  4. 3. Performance Analysis of Parametric Spectral Estimators

    Författare :Björn Völcker; KTH; []
    Nyckelord :Parameter estimation; line spectral estimation; estimator design; wideband signals; clustered sources.;

    Sammanfattning : .... LÄS MER

  5. 4. 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

  7. 5. The diagnostic potential of the He I D3 spectral line in the solar atmosphere

    Författare :Tine Libbrecht; Jaime de la Cruz Rodríguez; Jorrit Leenaarts; Göran Scharmer; Valentín Martínez Pillet; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; Line formation; Chromosphere; Spectro-Polarimetry; Flares; Reconnection; Astronomy; astronomi;

    Sammanfattning : The research question of my PhD is in a way a simple one: what can observations of the He I D3 line teach us about the solar chromosphere? This optical spectral line at 5876 Å is generally formed in the upper chromosphere, and is sensitive to the local magnetic field. The He I D3 line is also indirectly sensitive to heating of the transition region and corona, since it is resulting from a transition that occurs between levels in the triplet system of neutral helium. LÄS MER