Spelling suggestions: "subject:"epectral theory (amathematics)"" "subject:"epectral theory (bmathematics)""
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Dictionary projection pursuit : a wavelet packet technique for acoustic spectral feature extractionRutledge, Glen Alfred 01 March 2018 (has links)
This thesis uses the powerful mathematics of wavelet packet signal processing to efficiently extract features from sampled acoustic spectra for the purpose of discriminating between different classes of sounds. An algorithm called dictionary projection pursuit (DPP) is developed which is a fast approximate version of the projection pursuit (PP) algorithm [P.J. Huber Projection Pursuit, Annals of Statistics, 13 ( 2) 435–525, 1985]. When used with a wavelet packet or cosine packet dictionary, this algorithm is significantly faster than the PP algorithm with relatively little degradation in performance provided that the multivariate vectors are samples of an underlying continuous waveform or image. The DPP algorithm is applied to the problem of approximating the Karhunen-Loève transform (KLT) in high dimensional spaces and simulations are performed to compare this algorithm to Wickerhauser's approximate KLT algorithm [M.V. Wickerhauser. Adapted Wavelet Analysis from Theory to Software, A.K. Peters Ltd, 1994]. Both algorithms perform very well relative to the eigenanalysis form of the KLT algorithm at a small fraction of the computational cost.
The DPP algorithm is then applied to the problem of finding discriminant features in acoustic spectra for sound recognition tasks; extensive simulations are performed to compare this algorithm to previously developed dictionary methods for discrimination such as Saito and Coifman's local discriminant bases [N. Saito and R. Coifman. Local Discriminant Bases and their Applications. Journal of Mathematical Imaging and Vision, 5 (4) 337–358, 1995] and Buckheit and Donoho's discriminant pursuit [J. Buckheit and D. Donoho. Improved Linear Discrimination Using Time-Frequency Dictionaries. Proceedings of SPIE Wavelet Applications in Signal and Image Processing III Vol 2569, 540–551, July, 1995]. It is found that each feature extraction algorithm performs well under different conditions, but the DPP algorithm is the most flexible and consistent performer. / Graduate
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On the role of subharmonic functions in the spectral theory of general Banach algebrasMoolman, Ruan 23 February 2010 (has links)
M.Sc.
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Time series forecasting and model selection in singular spectrum analysisDe Klerk, Jacques 11 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2002 / ENGLISH ABSTRACT: Singular spectrum analysis (SSA) originated in the field of Physics. The technique is
non-parametric by nature and inter alia finds application in atmospheric sciences,
signal processing and recently in financial markets. The technique can handle a very
broad class of time series that can contain combinations of complex periodicities,
polynomial or exponential trend. Forecasting techniques are reviewed in this study,
and a new coordinate free joint-horizon k-period-ahead forecasting formulation is
derived. The study also considers model selection in SSA, from which it become
apparent that forward validation results in more stable model selection.
The roots of SSA are outlined and distributional assumptions of signal senes are
considered ab initio. Pitfalls that arise in the multivariate statistical theory are
identified.
Different approaches of recurrent one-period-ahead forecasting are then reviewed.
The forecasting approaches are all supplied in algorithmic form to ensure effortless
adaptation to computer programs. Theoretical considerations, underlying the
forecasting algorithms, are also considered. A new coordinate free joint-horizon kperiod-
ahead forecasting formulation is derived and also adapted for the multichannel
SSA case.
Different model selection techniques are then considered. The use of scree-diagrams,
phase space portraits, percentage variation explained by eigenvectors, cross and
forward validation are considered in detail. The non-parametric nature of SSA
essentially results in the use of non-parametric model selection techniques.
Finally, the study also considers a commercial software package that is available and
compares it with Fortran code, which was developed as part of the study. / AFRIKAANSE OPSOMMING: Singulier spektraalanalise (SSA) het sy oorsprong in die Fisika. Die tegniek is nieparametries
van aard en vind toepassing in velde soos atmosferiese wetenskappe,
seinprossesering en onlangs in finansiële markte. Die tegniek kan 'n wye
verskeidenheid tydreekse hanteer wat kombinasies van komplekse periodisiteite,
polinomiese- en eksponensiële tendense insluit. Vooruitskattingstegnieke word ook in
hierdie studie beskou, en 'n nuwe koërdinaatvrye gesamentlike horison k-periodevooruitskattingformulering
word afgelei. Die studie beskou ook model seleksie in
SSA, waaruit duidelik blyk dat voorwaartse validasie meer stabiele model seleksie tot
gevolg het.
Die agtergrond van SSA word ab initio geskets en verdelingsaannames van seinreekse
beskou. Probleemgevalle wat voorkom in die meervoudige statistiese teorie word
duidelik geïdentifiseer.
Verskeie tegnieke van herhalende toepassing van een-periode-vooruitskatting word
daarna beskou. Die benaderings tot vooruitskatting word in algororitmiese formaat
verskaf wat die aanpassing na rekenaarprogrammering vergemaklik. Teoretiese
vraagstukke, onderliggend aan die vooruitskattings-algortimes, word ook beskou. 'n
Nuwe koërdinaatvrye gesamentlike horison k-periode-vooruitskattingsformulering
word afgelei en aangepas vir die multikanaal SSA geval.
Verskillende model seleksie tegnieke is ook beskou. Die gebruik van "scree"-
diagramme, fase ruimte diagramme, persentasie variasie verklaar deur eievektore,
kruis- en voorwaartse validasie word ook aangespreek. Die nie-parametriese aard van
SSA noop die gebruik van nie-parametriese model seleksie tegnieke.
Die studie vergelyk laastens 'n kommersiële sagtewarepakket met die Fortran
bronkode wat as deel van hierdie studie ontwikkel is.
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Spectral theory in commutatively ordered banach algebrasMuzundu, Kelvin 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See full text. / AFRIKAANSE OPSOMMING: Sien volteks.
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Forward and inverse spectral theory of Sturm-Liouville operators with transmission conditionsBartels, Casey Ann January 2017 (has links)
Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Science, School of Mathematics, 2017. / ForwardandinversespectralproblemsconcerningSturm-Liouvilleoperatorswithoutdiscontinuitieshavebeenstudiedextensively. Bycomparison,therehasbeenlimitedworktacklingthecase where the eigenfunctions have discontinuities at interior points, a case which appears naturally in physical applications. We refer to such discontinuity conditions as transmission conditions. We consider Sturm-Liouville problems with transmission conditions rationally dependent on the spectral parameter. We show that our problem admits geometrically double eigenvalues, necessitating a new analysis. We develop the forward theory associated with this problem and also consider a related inverse problem. In particular, we prove a uniqueness result analogous to that of H. Hochstadt on the determination of the potential from two sequences of eigenvalues. In addition, we consider the problem of extending Sturm’s oscillation theorem, regarding the number of zeroes of eigenfunctions, from the classical setting to discontinuous problems with general constant coefficient transmission conditions / GR2018
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The spectral theory of complex sturm-liouville operatorsRace, David 16 July 2015 (has links)
A Thesis submitted to the Faculty of Science, University of the
Witwatersrand, Johannesburg for the Degree of Doctor of Philosophy.
Johannesburg, 1979
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On the spectrum of the metaplectic group with applications to Dedekind sumsVardi, Ilan January 1982 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Ilan Vardi. / Ph.D.
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Spectral mapping theorems and invariant manifolds for infinite-dimensional Hamiltonian systems /Stanislavova, Milena January 2000 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 71-78). Also available on the Internet.
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Sparse representations for recognitionCheng, Lei. Liu, Xiuwen. January 2004 (has links)
Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Xiuwen Liu, Florida State University, College of Arts and Sciences, Dept. of Computer Science. Title and description from dissertation home page (viewed June 17, 2004). Includes bibliographical references.
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Spectral mapping theorems and invariant manifolds for infinite-dimensional Hamiltonian systemsStanislavova, Milena January 2000 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 71-78). Also available on the Internet.
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