Search for dissertations about: "spectral theorem"

Showing result 1 - 5 of 17 swedish dissertations containing the words spectral theorem.

  2. 1. On the asymptotic spectral distribution of random matrices : closed form solutions using free independence

    Author : Jolanta Maria Pielaszkiewicz; Dietrich von Rosen; Martin Singull; Maciej A. Nowak; Linköpings universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Spectral distribution; R-transform; Stieltjes transform; Free probability; Freeness; Asymptotic freeness;

    Abstract : The spectral distribution function of random matrices is an information-carrying object widely studied within Random matrix theory. In this thesis we combine the results of the theory together with the idea of free independence introduced by Voiculescu (1985). READ MORE

  4. 2. Spectral estimates and Ambartsumian-type theorems for quantum graphs

    Author : Rune Suhr; Pavel Kurasov; Annemarie Luger; Alexei Rybkin; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Spectral estimates; quantum graphs; Ambartsumian; trigonometric polynomials; Mathematics; matematik;

    Abstract : This thesis consists of four papers and deals with the spectral theory of quantum graphs. A quantum graph is a metric graph equipped with a self-adjoint Schrödinger operator acting on functions defined on the edges of the graph subject to certain vertex conditions. READ MORE

  5. 3. Titchmarsh-Weyl M-function asymptotics and some results in the inverse spectral theory for vector-valued Sturm-Liouville equations and a certain higher order ordinary differential equation

    Author : Erik Andersson; Matematik (naturvetenskapliga fakulteten); []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Functions; differential equations; Funktioner; differentialekvationer; Paley-Wiener.; The generalized Fourier transform; A certain higher order ordinary differential equation; Borg-Marchenko theorems; Vector-valued Sturm-Liouville equations; Inverse spectral theory; Titchmarsh-Weyl M-function asymptotics; Asymptotics of solutions; Spectral measure;

    Abstract : This discourse is constituted by two separate reprots, where the first one offers an elementary deduction of the leading order term asymptotics for the Titchmarsh-Weyl M-function corresponding to a vector-valued Sturm-Liouville equation of the form -(PU')'+QU=zu, xin[0,b), with P^{-1},W,Q being hermitean with locally integrable entries; and under some additional conditions on P^{-1} and W. In the special case of P=W=I, we give some further asymptotic results for the same M-function. READ MORE

  6. 4. Some Markov Processes in Finance and Kinetics : Markov Processes

    Author : Mattias Sunden; Göteborgs universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; CGMY process; Collision kernel; Direct simulation Monte Carlo; Diffusion approximation; Extreme value theory; Feller process; Generalized hyperbolic process; Generalized $z$-process; Infinitesimal generator; Laplace-Beltrami operator; L evy Processes; Long-tailed distribution; Kac equation; Kac model; Markov process; Semigroup; Semi-heavy tailed distirbution; Spectral gap; Subexponential distibrution; Superexponential distribution; Tauberian theorem; Thermostat.; Diffusion approximation;

    Abstract : This thesis consists of four papers. The first two papers treat extremes for L\'evy processes, while papers three and four treat the Kac model with unbounded collision kernel. READ MORE

  7. 5. Miniaturized Hard Waveguides in Multifunction Array Antennas

    Author : Malcolm Ng Mou Kehn; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; interlaced arrays; Floquet theorem; reflector antennas; focal plane array; multifunction antennas; miniaturized waveguides; multilayer structures; spectral domain technique; periodic structures; aperture reuse; method of moments; soft and hard surfaces; array antennas;

    Abstract : Recent advances in technologies of wireless communications systems have led to an increasing desire for several antennas performing diverse functions at different frequencies to be integrated into a common radiating aperture. This gives rise to the so-called multifunction antenna, which affords the saving of scarce premium real estate and can alleviate problems arising from excessive antenna protrusions in aspects such as aerodynamics, aesthetics, and stealth capability in military applications. READ MORE