Sökning: "coherent structure"

Visar resultat 1 - 5 av 195 avhandlingar innehållade orden coherent structure.

  1. 1. Magnetism and Structure in Metallic Multilayers

    Författare :Erik Holmström; Turek Ilja; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Magnetism; Interfaces; Structure; KKR-ASA; CPA; Quantum Well; Fysik; Physics; Fysik;

    Sammanfattning : The interplay between magnetism and structure has been studied in magnetic multilayers by electronic structure calculations based on density functional theory and analyzed in terms of models. The main ideas behind the Korringa-Kohn-Rostocker Green’s function method are described and the implementation of the coherent potential approximation is outlined. LÄS MER

  3. 2. Analysis of Turbulent Flows-From Chaos to Structure

    Författare :Farideh Ghasempour; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Large Eddy Simulation; Vortex dynamics; Turbulence; Flow visualization; Vortex statistics; Coherent structure;

    Sammanfattning : The development of models for several phenomena occurring in turbulent single and multi-phase flows requires improved description and quantification of turbulent structures. Phenomena such as, for example, mixing, coalescence and break-up, are often fast and nonlinear. LÄS MER

  4. 3. Propagation of some coherent and partially coherent laser beams

    Författare :Yangjian Cai; Sailing He; Franco Gori; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; : dark hollow beam; elliptical Gaussian beam; flat-topped beam; twisted anisotropic Gaussian Schell-model; partial coherent; propagation; paraxial optical system; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

    Sammanfattning : In this thesis, we investigate the propagation of some coherent and partially coherent laser beams, including a dark hollow beam (DHB), an elliptical Gaussian beam (EGB), a flat-topped beam and a twisted anisotropic Gaussian Schell-model (TAGSM) beam, through a paraxial optical system or a turbulent atmosphere. Several theoretical models are proposed to describe a DHB of circular or non-circular symmetry. LÄS MER

  5. 4. Coherent Optical Transmission Systems : Performance and Coding Aspects

    Författare :Miu Yoong Leong; Sergei Popov; Gunnar Jacobsen; Enrico Forestieri; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Since the invention of fiber-optic systems in the 1970s, user demand has driven innovation forward, and each new generation of products has achieved higher data rates than its predecessor. Today, the most promising approach for further increasing data rates is coherent transmission with multi-level modulation and digital signal processing (DSP). LÄS MER

  7. 5. Sunspot structure and dynamics

    Författare :Luc Rouppe van der Voort; Wolfgang Schmidt; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Astronomi; Astronomy; astronomi;

    Sammanfattning : Fundamental physical processes occur on small spatial scales in the solar atmosphere and high-spatial-resolution observations are necessary to test theoretical models. This thesis presents high-spatial-resolution observations of sunspots obtained with the Swedish solar telescopes on La Palma: the Swedish Vacuum Solar Telescope (SVST) and its successor the Swedish 1-m Solar Telescope (SST). LÄS MER