Sökning: "linear and nonlinear waves"

Visar resultat 21 - 25 av 50 avhandlingar innehållade orden linear and nonlinear waves.

  1. 21. On Steady Water Waves and Their Properties

    Författare :Mats Ehrnström; Matematik (naturvetenskapliga fakulteten); []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Particle trajectories; Water waves; Vorticity; Maximum principles; Elliptic equations;

    Sammanfattning : Abstract: This thesis consists of four papers related to various aspects of steady water waves. Paper I: Deep-water waves with vorticity: symmetry and rotational behaviour. We show that for steady, periodic, and rotational gravity deep-water waves, a monotone surface profile between troughs and crests implies symmetry. LÄS MER

  3. 22. Degenerating Orr-Sommerfeld eigenmodes and development of three-dimensional perturbations

    Författare :Rajaratnam Shanthini; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Strömningslära; Fluid Mechanics;

    Sammanfattning : Degeneracies of temporally damped Orr-Sommerfeld eigenmodes are studied primarily for plane Poiseuille flow. The discrete spectrum of the eigenmodes is shown to possess infinitely many degeneracies, each appearing at a certain combination of k (the modulus of resultant wavenumber) and α R (the streamwise wavenumber times the Reynolds number). LÄS MER

  4. 23. Nonlinear Theory of Partially Coherent Optical Waves

    Författare :Tobias Hansson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nonlinear optics; partial coherence; beam collapse; saturable logarithmic media; soliton interaction; dressing method; parabolic beams; Wigner transform; invariants; modulational instability;

    Sammanfattning : Nonlinear effects arise in optics as a consequence of the medium properties being modified by the presence of light. Of particular interest are situations where the effect of the nonlinearity can be described by an intensity dependent refractive index and the subsequent interplay with dispersion and diffraction. LÄS MER

  5. 24. Modelling of IC-Engine Intake Noise

    Författare :Magnus Knutsson; Mats Åbom; Yves Auregán; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; IC-engine; intake noise; gas dynamics; linear source data; frequency domain; 2-port; losses; air cleaner unit; filter paper; flow; FEM; BEM; charge air cooler; narrow tube; Acoustics; Akustik;

    Sammanfattning : Shorter product development cycles, densely packed engine compartments and intensified noiselegislation increase the need for accurate predictions of IC-engine air intake noise at earlystages. The urgent focus on the increasing CO2 emissions and the efficiency of IC-engines, aswell as new techniques such as homogeneous charge compression ignition (HCCI) mightworsen the noise situation. LÄS MER

  7. 25. Stability and Mobility of Localized and Extended Excitations in Nonlinear Schrödinger Models

    Författare :Michael Öster; Magnus Johansson; Sergej Flach; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Non-linear dynamics; chaos; Icke-linjär dynamik; kaos;

    Sammanfattning : This thesis is mainly concerned with the properties of some discrete nonlinear Schrödinger equations. These naturally arise in many different physical contexts as the limiting form of general dynamical lattice equations that incorporate nonlinearity and coupling. LÄS MER