Global ETD Search

1	Generalized Krylov subspace methods with applications Yu, Xuebo 07 August 2014 (has links) No description available. Mathematics Tikhonov regularization generalized Krylov method generalized Golub-Kahan flexible Arnoldi ill-posed problem pseudospectrum rational Arnoldi
2	Novi indikatori stabilnosti za empirijske trofičke mreže / New stability indicators for the empirical food webs Cvetković Dragana 31 October 2017 (has links) <p>Ova doktorska disertacija uvodi nov pristup ispitivanju stabilnosti dinamičkih<br />sistema, korišćenjem teorije pseudospektra. Na taj način se postojeći pojam<br />stabilnosti profinjuje pojmom robusne stabilnosti, koji mnogo adekvatnije<br />opisuje realnu ekološku stabilnost. Razvijen je nov matematički alat za<br />izračunavanje indikatora stabilnosti, koji je zatim ilustrovan na primeru dva<br />ekosistema tla, sa po četiri uzorka, u četiri različita stadijuma razvoja.</p> / <p>This doctoral dissertation establishes a novel approach to the stability analysis of<br />dynamical systems, in terms of matrix pseudospectrum. In that manner, the existing<br />concept of stability has undergone essential refinement so as to give birth to the<br />concept of robust stability, which has the ability to capture the ecological stability at a<br />more adequate level. Additionally, within the framework of the dissertation, a new<br />mathematical tool for the stability indicators computation has been developed, which<br />has then been used to illustrate theoretical results in form of two soil ecosystems,<br />each of them sampled four times, all of them observed in four distinct stages of<br />evolution.</p>
3	Non-selfadjoint operator functions Torshage, Axel January 2017 (has links) 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. In this thesis non-selfadjoint operator functions are studied and several methods for obtaining properties of unbounded non-selfadjoint operator functions are presented. Equivalence is used to characterize operator functions since two equivalent operators share many significant characteristics such as the spectrum and closeness. Methods of linearization and other types of equivalences are presented for a class of unbounded operator matrix functions. To study properties of the spectrum for non-selfadjoint operator functions, the numerical range is a powerful tool. The thesis introduces an optimal enclosure of the numerical range of a class of unbounded operator functions. The new enclosure can be computed explicitly, and it is investigated in detail. Many properties of the numerical range such as the number of components can be deduced from the enclosure. Furthermore, it is utilized to prove the existence of an infinite number of eigenvalues accumulating to specific points in the complex plane. Among the results are proofs of accumulation of eigenvalues to the singularities of a class of unbounded rational operator functions. The enclosure of the numerical range is also used to find optimal and computable estimates of the norm of resolvent and a corresponding enclosure of the ε-pseudospectrum. Non-linear spectral problem numerical range pseudospectrum resolvent estimate equivalence after extension block operator matrices operator functions operator pencil spectral divisor joint numerical range Mathematical Analysis Matematisk analys
4	Diverse Polarization Extension to MUSIC Applied to a Circular Array of H-Plane Horns Whelan, Jedidiah J. January 2010 (has links) No description available. Aerospace Engineering Electrical Engineering Electromagnetism Engineering Radiation MUSIC polarization circular array angle of arrival direction of arrival aoa df horn antenna horn antennas schmidt ferrera pseudospectrum diverse polarization diversely polarized RADAR radiation pattern

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