Sökning: "spectral decomposition"

Visar resultat 26 - 30 av 56 avhandlingar innehållade orden spectral decomposition.

  1. 26. Studies of vector tomography

    Författare :Kent Stråhlén; Matematik LTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Doppler tomography; Doppler Radon transform; local tomography; vectorial k-plane transform; vectorial Radon transform; k-plane transform; Radon transform; tomography; vector tomography; Mathematics; Matematik;

    Sammanfattning : The motivation to study the kind of problems appearing in this thesis has been ultrasound measurements of flows, from which velocity spectra along lines can be determined. These velocity spectra can mathematically be described by a new non-linear transform, here called the Doppler Spectral Transform (DST). LÄS MER

  3. 27. Phase-Sensitive Parametric Signal Processing in Optical Communications

    Författare :Abel Lorences Riesgo; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : This thesis covers the analysis of several schemes for parametric processing in fiberoptic communication systems, focusing mainly on phase-sensitive processing. Vector phase-sensitive amplifiers are characterized and phase regeneration of a dualpolarization (DP)-binary phase-shift keying signal (BPSK) signal is experimentally demonstrated. LÄS MER

  4. 28. Space-adaptive simulation of transition and turbulence in shear flows

    Författare :Daniele Massaro; Philipp Schlatter; Saleh Rezaeiravesh; Alfredo Pinelli; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Turbulence; global stability; coherent structures; adaptive mesh refinement; Turbulens; global stabilitet; koherenta strukturer; adaptiv nätförfining; Teknisk mekanik; Engineering Mechanics;

    Sammanfattning : Transitional and turbulent shear flows are ubiquitous, from the boundary layer developing on an aeroplane wing to the flow within the aortic arch. In this thesis, we study wall-bounded and free shear flows through direct numerical simulations. LÄS MER

  5. 29. A study of multilevel models with block circular  symmetric covariance structures

    Författare :Yuli Liang; Tatjana von Rosen; Dietrich von Rosen; Abdullah Almasri; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Block circular symmetry; Covariance matrix; Explicit solution; Maximum likelihood estimator; Multilevel model; Spectrum; statistik; Statistics; Matematik;

    Sammanfattning : This thesis concerns the study of multilevel models with specific patterned covariance structures and addresses the issues of maximum likelihoodestimation. In particular, circular symmetric hierarchical datastructures are considered. LÄS MER

  7. 30. Studies on adverse-pressure-gradient turbulent boundary layers on wings

    Författare :Alvaro Tanarro; Philipp Schlatter; Ricardo Vinuesa; Omid Omidyeganeh; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The present licentiate thesis addresses the use of well-resolved simulations to simulate turbulent boundary layers (TBL) subjected to adverse pressure gradients. Within the thesis a wide variety of analyses are performed, and a method to improve the performance of the simulations is presented. LÄS MER