Sökning: "resolvent analysis"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden resolvent analysis.

  1. 1. Non-selfadjoint operator functions

    Författare :Axel Torshage; Christian Engström; Marco Marletta; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Non-linear spectral problem; numerical range; pseudospectrum; resolvent estimate; equivalence after extension; block operator matrices; operator functions; operator pencil; spectral divisor; joint numerical range; Mathematics; matematik;

    Sammanfattning : Spectral properties of linear operators and operator functions can be used to analyze models in nature. When dispersion and damping are taken into account, the dependence of the spectral parameter is in general non-linear and the operators are not selfadjoint. LÄS MER

  3. 2. Resolvent Estimates and Bounds on Eigenvalues for Schrödinger and Dirac Operators

    Författare :Alexandra Enblom; Vladimir Kozlov; Ari Laptev; David Krejcirik; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spectral theory; Schrödinger operators; polyharmonic operators; Dirac operators; non-self-adjoint perturbations; complex potential; estimation of eigenvalues; Carleman inequalities; Hardy inequalities;

    Sammanfattning : This thesis concerns the spectral theory of Schrödinger and Dirac operators. The main results relate to the problems of estimating perturbed eigenvalues. The thesis is based on four papers.The first paper focuses on the problem of localization of perturbed eigenvalues for multidimensional Schrödinger operators. LÄS MER

  4. 3. Some Resolvent Estimates in Harmonic Analysis

    Författare :Anders Dahlner; Matematik (naturvetenskapliga fakulteten); []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; field theory; Number Theory; algebra; algebraic geometry; Talteori; group theory; Tauberian theorem. Quantitative inversion. Cesaro operator. Bishops property beta.; algebraisk geometri; fältteori; gruppteori;

    Sammanfattning : This thesis contains three papers about three different estimates of resolvents in harmonic analysis. These papers are: Paper 1. ``A Wiener tauberian theorem for weighted convolution algebras of zonal functions on the automorphism group of the unit disc'' Paper 2. ``Uniform spectral radius and compact Gelfand transform'' Paper 3. LÄS MER

  5. 4. Modelling and control of turbulent and transitional flows

    Författare :Pierluigi Morra; Dan S. Henningson; Ardeshir Hanifi; André V. G. Cavalieri; Shervin Bagheri; Aimee S. Morgans; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; reduced order modeling; flow control; resolvent analysis; transi- tional boundary layer; turbulent boundary layer; drag reduction; high-fidelity wall-turbulence modelling; modellreduktion; strömningskontroll; resolvent analys; laminär- turbulent omslag; turbulent gränsskikt; motståndsminskning; väggturbulens modellering; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The dynamics of fluid motion can accurately be described by the Navier– Stokes equations. Manipulating these equations to reduce their complexity but preserving their main characteristics has always been a key research activity in the field of fluid mechanics. LÄS MER

  7. 5. Spectra of elliptic operators and applications

    Författare :Medet Nursultanov; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Helmholtz and Maxwell s equations; functional calculus; electromagnetic waveguide; acoustic waveguide; Sturm-Liouville operator; singular potential; asymptotics of eigenvalues; point interactions.;

    Sammanfattning : In this thesis we consider several problems related to elliptic equations. Namely, we investigate Helmholtz and Maxwell's equations in Paper I and Sturm-Liouville spectral problem in Papers II,III. In Paper I we study time-harmonic electromagnetic and acoustic waveguide, modeled by an in�nite cylinder with a non-smooth cross section. LÄS MER