Sökning: "Time Spectral"

Visar resultat 1 - 5 av 550 avhandlingar innehållade orden Time Spectral.

  1. 1. Time Spectral Methods - Towards Plasma Turbulence Modelling

    Författare :Kristoffer Lindvall; Jan Scheffel; Carl Sovinec; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Fusion; Turbulence; Micro-instabilities; Time-spectral; Navier-Stokes; MHD; Weiland model; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : Energy comes in two forms; potential energy and kinetic energy. Energyis stored as potential energy and released in the form of kinetic energy. This process of storage and release is the basic strategy of all energy alternatives in use today. This applies to solar, wind, fossil fuels, and the list goes on. LÄS MER

  3. 2. Advanced Spectral Analysis with Applications

    Författare :Niclas Sandgren; Peter Stoica; Thomas L. Marzetta; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; frequency-selective spectral analysis; damped sinusoidal model; prior knowledge; multichannel spectroscopy; phantom experimental data; in-vivo in-vitro data analysis; area-selective analysis; cepstrum thresholding; total-variance reduction; two-dimensional spectral estimation; spectral smoothing; irregular sampling; CARMA signals; Signal processing; Signalbehandling;

    Sammanfattning : Spectral analysis has advanced the last decades as a signal processing tool to extract significant information about certain properties of measured data. The practical use of spectral analysis techniques in time-series analysis has been emphasized in the immense amount of previous literature in the field and by a rapidly growing number of applications. LÄS MER

  4. 3. Efficient Solvers for Space-Time Discontinuous Galerkin Spectral Element Methods

    Författare :Lea Miko Versbach; Numerisk analys; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Discontinuous Galerkin Method; Spectral Element Method; Finite Volume Method; Implicit Schemes; Preconditioner; Multigrid Method; Space-Time; Lobatto IIIC Method; Local Fourier Analysis;

    Sammanfattning : In this thesis we study efficient solvers for space-time discontinuous Galerkin spectral element methods (DG-SEM). These discretizations result in fully implicit schemes of variable order in both spatial and temporal directions. LÄS MER

  5. 4. Type Ia Supernova Cosmology : Quantitative Spectral Analysis

    Författare :Gastón Folatelli; Ariel Goobar; Enrico Cappellaro; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supernova; Cosmology; Spectroscopy; Physics; Fysik;

    Sammanfattning : Type Ia supernovae have been successfully used as standardized candles to study the expansion history of the Universe. In the past few years, these studies led to the exciting result of an accelerated expansion caused by the repelling action of some sort of dark energy. LÄS MER

  7. 5. High order summation-by-parts methods in time and space

    Författare :Tomas Lundquist; Jan Nordström; Peter Eliasson; David A. Kopriva; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; summation-by-parts; time integration; stiff problems; weak initial conditions; high order methods; simultaneous-approximation-term; finite difference; discontinuous Galerkin; spectral methods; conservation; energy stability; complex geometries; non-conforming grid interfaces; interpolation;

    Sammanfattning : This thesis develops the methodology for solving initial boundary value problems with the use of summation-by-parts discretizations. The combination of high orders of accuracy and a systematic approach to construct provably stable boundary and interface procedures makes this methodology especially suitable for scientific computations with high demands on efficiency and robustness. LÄS MER