Sökning: "spectral theory"

Visar resultat 21 - 25 av 237 avhandlingar innehållade orden spectral theory.

  1. 21. Inverse Problems in Analytic Interpolation for Robust Control and Spectral Estimation

    Författare :Johan Karlsson; Anders Lindquist; Alberto Isidori; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nevanlinna-Pick Interpolation; Approximation; Model Reduction; Robust Control; Gap-robustness; Sensitivity Shaping; Entropy functional; Spectral Estimation; Weak*-topology; Monge-Kantorovic Transportation; Optimization; systems theory; Optimeringslära; systemteori;

    Sammanfattning : This thesis is divided into two parts. The first part deals with theNevanlinna-Pick interpolation problem, a problem which occursnaturally in several applications such as robust control, signalprocessing and circuit theory. We consider the problem of shaping andapproximating solutions to the Nevanlinna-Pick problem in a systematicway. LÄS MER

  3. 22. Modeling and Sampling of Spectrally Structured Signals

    Författare :Filip Elvander; Statistical Signal Processing Group; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; spectral estimation; parameter estimation; optimal mass transport; covariance interpolation; misspecified models; inharmonicity;

    Sammanfattning : This thesis consists of five papers concerned with the modeling of stochastic signals, as well as deterministic signals in stochastic noise, exhibiting different kinds of structure. This structure is manifested as the existence of finite-dimensional parameterizations, and/or in the geometry of the signals' spectral representations. LÄS MER

  4. 23. Some Contributions to Filtering, Modeling and Forecasting of Heteroscedastic Time Series

    Författare :Pär Stockhammar; Lars-Erik Öller; Daniel Thorburn; Agustin Maravall; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Heteroscedasticity; variance stabilizing filters; the mixed Normal - Asymmetric Laplace distribution; density forecasting; detrending filters; spectral analysis; the connection between financial data and economic growth; Statistics; Statistik; Statistics; statistik;

    Sammanfattning : Heteroscedasticity (or time-dependent volatility) in economic and financial time series has been recognized for decades. Still, heteroscedasticity is surprisingly often neglected by practitioners and researchers. This may lead to inefficient procedures. LÄS MER

  5. 24. Selfconsistent theory of superconductivity in unconventional superconductors

    Författare :Fabian Schrodi; Peter M. Oppeneer; Alex Aperis; Jörg Schmalian; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; superconductivity; unconventional; Eliashberg theory;

    Sammanfattning : Superconductivity is broadly believed to stem from either electron-phonon interaction (EPI) or from purely electronic mechanisms, such as antiferromagnetic spin fluctuations. For many materials the discussion about which of these interactions is the dominant "pairing glue" is still ongoing. LÄS MER

  7. 25. Theory of water-proton spin relaxation in complex biological systems

    Författare :Zhiwei Chang; Biofysikalisk kemi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; spin relaxation theory; immobilized macromolecules; magnetic relaxation dispersion; integral longitudinal relaxation rate; stochastic Liouville equations; multi-spin systems; cross-mode relaxation; spectral density functions;

    Sammanfattning : In complex biological systems (e.g. gels, cross-linked proteins and biological tissues), the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. LÄS MER