Sökning: "Wigner transform"

Hittade 4 avhandlingar innehållade orden Wigner transform.

  1. 1. Aspects of Wave Interaction in Nonlinear Media

    Författare :Björn Hall; [2005]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nonlinear Schrödinger equation; incoherent solitons; partial incoherence; nonlinear wave interaction; Gross-Pitaevskii equation; modulational instability; collective dynamics; Wigner transform; nonlinear guided waves; Bose-Einstein condensation;

    Sammanfattning : Selected aspects of various types of nonlinear wave interaction are investigated. These aspects are studied in terms of models described by Nonlinear Schrödinger equations, mainly analytically and numerically, but also experimentally. LÄS MER

  2. 2. Nonlinear Theory of Partially Coherent Optical Waves

    Författare :Tobias Hansson; [2011]
    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

  3. 3. Nonlinear Propagation of Partially Incoherent Light

    Författare :Lukasz Helczynski-Wolf; [2005]

    Sammanfattning : This thesis deals with consequences of partial incoherence on light propagation in nonlinear media. A new approach, based on the Wigner transform method, has beed developed and used to investigate several important problems in nonlinear light propagation. LÄS MER

  4. 4. Estimation and Classification of Non-Stationary Processes : Applications in Time-Frequency Analysis

    Detta är en avhandling från Centre for Mathematical Sciences, Lund University

    Författare :Johan Brynolfsson; Lund University.; Lunds universitet.; Lund University.; Lund University.; Lunds universitet.; [2019-05-17]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Time-Frequency Estimation; Parameter Estimation; Reassignment method; Non-Stationary Processes; Smooth spectral estimation; Neural Networks;

    Sammanfattning : This thesis deals with estimation and classification problems of non-stationary processes in a few special cases.In paper A and paper D we make strong assumptions about the observed signal, where a specific model is assumed and the parameters of the model are estimated. LÄS MER