Sökning: "coherent structures"

Visar resultat 1 - 5 av 135 avhandlingar innehållade orden coherent structures.

  1. 1. Coherent structures and control in wall-bounded turbulent flows

    Författare :Marco Atzori; Philipp Schlatter; Ricardo Vinuesa; Oscar Flores; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; Turbulent boundary layers; numerical simulations; coherent structures; predetermined flow control.; Turbulenta gränsskikt; numeriska simuleringar; koherenta strukturer; förutbestämd flödeskontroll; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : This thesis is concerned with two distinct topics related to the study of wall-bounded turbulence: the connection between instantaneous three-dimensional coherent structures and mean-flow properties, and the development and analysis of pre-determined control techniques for adverse-pressure-gradient boundary layers.We examined regions with intense velocity fluctuations in various flowcases. LÄS MER

  2. 2. Space Plasma Dynamics : Instabilities, Coherent Vortices and Covariant Parametrization

    Författare :David Sundkvist; Jan-Erik Wahlund; Andris Vaivads; Stuart Bale; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; space physics; plasma; instabilities; turbulence; coherent structures; vortex; self-organization; magnetosphere; waves; electromagnetism; covariant; space instrumentation; Rymd- och plasmafysik; Space physics; Rymdfysik;

    Sammanfattning : The magnetospheric cusps are two funnel-like regions of Earth's magnetosphere where solar wind plasma can have direct access to the ionosphere. The cusps are very dynamic regions where wave-particle interactions continuously take place and redistribute energy among different particle populations. LÄS MER

  3. 3. On Coherent and Non-coherent Receiver Structures for Impulse Radio UWB Systems

    Författare :Muhammad Gufran Khan; []

    Sammanfattning : The demand and growth of short-range wireless communications has been tremendous in the past few years for a diverse range of applications. There is significant interest in ultra wideband (UWB) as a physical layer technology for both high-data-rate (HDR), and low power, low-data-rate (LDR) short-range communications. LÄS MER

  4. 4. Ultrafast Coherent X-ray Diffractive Nanoimaging

    Författare :Filipe R. N. C. Maia; Janos Hajdu; David van der Spoel; Keith Nugent; Uppsala universitet; []
    Nyckelord :XFEL; Phasing; Image Reconstruction; Single Particle Imaging; Ultrafast Diffraction; X-ray diffraction; Coherent Diffractive Imaging; CXDI;

    Sammanfattning : X-ray lasers are creating unprecedented research opportunities in physics,chemistry and biology. The peak brightness of these lasers exceeds presentsynchrotrons by 1010, the coherence degeneracy parameters exceedsynchrotrons by 109, and the time resolution is 105 times better. LÄS MER

  5. 5. Coherent Diffractive Imaging with X-ray Lasers

    Författare :Max Felix Hantke; Filipe R. N. C. Maia; Janos Hajdu; Martin Svenda; Edgar Weckert; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; NATURAL SCIENCES; coherent diffractive X-ray imaging; lensless imaging; coherent X-ray diffractive imaging; flash diffractive imaging; single particle imaging; aerosol injection; electrospray injection; substrate-free sample delivery; carboxysome; phase retrieval; X-ray diffraction software; X-ray free-electron laser; XFEL; FEL; CXI; CDI; CXDI; FXI;

    Sammanfattning : The newly emerging technology of X-ray free-electron lasers (XFELs) has the potential to revolutionise molecular imaging. XFELs generate very intense X-ray pulses and predictions suggest that they may be used for structure determination to atomic resolution even for single molecules. LÄS MER