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Visar resultat 1 - 5 av 25 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Wave interactions by Hamiltonian methods

    Författare :Krister Wiklund; Umeå universitet; []
    Nyckelord :Hamiltonian formulation; wave interaction; stability; variational principles;

    Sammanfattning : This thesis is devoted to the description of fluids and gases from a Hamiltonian point of view. The method we apply is a development of the theory invented by Hamilton (1805-1865). The original formulation is restricted to a certain family of dynamical variables; the canonical variables. LÄS MER

  3. 2. Nonlinear interaction and propagation of gravitational and electromagnetic waves in plasmas

    Författare :Martin Servin; Gert Brodin; Lennart Stenflo; Demetrios Papadopoulos; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Theoretical physics; general relativity; plasma; gravitational waves; electromagnetic waves; nonlinear; wave interaction; wave propagation; Teoretisk fysik; Physics; Fysik; teoretisk fysik; Theoretical Physics;

    Sammanfattning : Gravitational waves and electromagnetic waves are important as carriers of energy and information. This thesis is devoted to the study of the propagation and interaction of these waves in plasmas, with emphasis on nonlinear effects and applications within astrophysics. LÄS MER

  4. 3. Short Pulses in Engineered Nonlinear Media

    Författare :Stefan Holmgren; Fredrik Laurell; Derryck Reid; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; nonlinear optics; KTiOPO4; frequency conversion; mode-locked lasers; ultra-fast lasers; visible lasers; short pulses; ultrafast nonlinear optics; diagnostic applications of nonlinear optics; nonlinear optical materials; Physics; Fysik;

    Sammanfattning : Short optical pulses and engineered nonlinear media is a powerful combination. Mode locked pulses exhibit high peak powers and short pulse duration and the engineered ferro-electric KTiOPO4 facilitates several different nonlinear processes. LÄS MER

  5. 4. Unravelling Consistent Spin-2 Interactions

    Författare :Mikael von Strauss; Sayed Fawad Hassan; Mikhail Volkov; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Modified Gravity; Massive Spin-2; Spin-2 Interactions; teoretisk fysik; Theoretical Physics;

    Sammanfattning : Recently, a unique formulation of a classically consistent theory of massive spin-2 fields has emerged. In this thesis I address a few of the primary questions that arise once such a theory is available. LÄS MER

  7. 5. Waves and instabilities in quantum plasmas

    Författare :Shahid Ali; Padma Kant Shukla; Mattias Marklund; Jose Tito Mendonca; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Quantum mechanical effects; dusty plasma; linear and nonlinear waves; instabilities; nonlinear wave interactions; density gradients; magnetoplasmas.; Plasma physics; Plasmafysik;

    Sammanfattning : The study of waves and instabilities in quantum plasmas is of fundamental importance for understanding collective interactions in superdense astrophysical objects, in high intense laser-plasma/solid-matter interactions, in microelectronic devices and metallic nanostructures. In dense quantum plasmas, there are new pressure laws associated with the Fermi-Dirac distribution functions and new quantum forces associated with the quantum Bohm potential and the Bohr magnetization involving electron ½ spin. LÄS MER