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Dissertations / Theses on the topic 'Fourier decomposition'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 July 2025

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1

Liu, Zhu Lin. "Speech synthesis via adaptive Fourier decomposition." Thesis, University of Macau, 2011. http://umaclib3.umac.mo/record=b2493215.

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Li, Zhi Xiong. "A revision of adaptive Fourier decomposition." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590642.

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Shi, Rong. "Applications of adaptive Fourier decomposition to financial data." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2592936.

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4

Mai, Wei Xiong. "Time frequency distribution associated with adaptive Fourier decomposition and its variation." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590643.

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Avetisyan, Zhirayr. "Mode decomposition and Fourier analysis of physical fields in homogeneous cosmology." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-107907.

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In this work the methods of mode decomposition and Fourier analysis of quantum fields on curved spacetimes previously available mainly for the scalar fields on Friedman-Robertson-Walker spacetimes are extended to arbitrary vector fields on general spatially homogeneous spacetimes. This is done by developing a rigorous unified framework which incorporates mode decomposition, harmonic analysis and Fourier analysis. Explicit constructions are performed for a variety of situations arising in homogeneous cosmology. A number of results concerning classical and quantum fields known for very restricte

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Blackburn, John William Teasdale. "High-resolution Fourier transform ion cyclotron resonance mass spectrometry and nuclear magnetic resonance spectroscopy of humic substances." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31149.

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Humic substances (HS) are described as a complex mixture of organic molecules formed by incomplete decomposition of plant, animal and microbial matter. They are found in soil, water and air and have many environmental roles, e.g. water retention and metal ion binding in soil. Despite their importance, the molecular composition of HS is poorly understood. This is mostly because of an inability to separate individual molecules from these complex mixtures and then characterise them by standard analytical methods such as NMR and MS. In order improve the understanding of these important mixtures I

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7

Liu, Xiaohua. "Anion-Peptide Adduct Formation and Decomposition As Studied by Fourier Transform Ion Cyclotron Resonance (FT-ICR) Mass Spectrometry." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1748.

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A new “best match” match model has been developed to account for adduct formation on multiply charged peptides observed in negative ion electrospray mass spectrometry. To obtain a stable adduct, the model necessitates an approximate matching of apparent gas-phase basicity (GBapp) of a given proton bearing site on the peptide with the gas-phase basicity (GB) of the anion attaching at that site. Evidence supporting the model is derived from the fact that singly charged adducts were only observed for lower GB anions: HSO4-, I-, CF3COO-. Ions that have medium GBs (NO3-, Br-, H2PO4-) only form addu

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Workalemahu, Tsegaselassie. "Singular Value Decomposition in Image Noise Filtering and Reconstruction." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/math_theses/52.

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The Singular Value Decomposition (SVD) has many applications in image processing. The SVD can be used to restore a corrupted image by separating significant information from the noise in the image data set. This thesis outlines broad applications that address current problems in digital image processing. In conjunction with SVD filtering, image compression using the SVD is discussed, including the process of reconstructing or estimating a rank reduced matrix representing the compressed image. Numerical plots and error measurement calculations are used to compare results of the two SVD image re

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9

Eliasson, Bengt. "Numerical Vlasov–Maxwell Modelling of Space Plasma." Doctoral thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2929.

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The Vlasov equation describes the evolution of the distribution function of particles in phase space (x,v), where the particles interact with long-range forces, but where shortrange "collisional" forces are neglected. A space plasma consists of low-mass electrically charged particles, and therefore the most important long-range forces acting in the plasma are the Lorentz forces created by electromagnetic fields. What makes the numerical solution of the Vlasov equation a challenging task is that the fully three-dimensional problem leads to a partial differential equation in the six-dimensional

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10

Colom, i. Bernadich Miquel. "Measuring the Characteristic Sizes of Convection Structures in AGB Stars with Fourier Decomposition Analyses : the Stellar Intensity Analyzer (SIA) Pipeline." Thesis, Uppsala universitet, Teoretisk astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414041.

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Context. Theoretical studies predict that the length scale of convection in stellar atmospheres isproportional to the pressure scale height, which implies that giant and supergiant stars should have convection granules of sizes comparable to their radii. Numerical simulations and the observation of anisotropies on stellar discs agree well with this prediction. Aims. To measure the characteristic sizes of convection structures of models simulated with the CO5BOLD code, to look at how they vary between models and to study their limitations due to numerical resolution. Methods. Fourier analyses a

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11

Avetisyan, Zhirayr [Verfasser], Rainer [Akademischer Betreuer] Verch, Rainer [Gutachter] Verch, and Claudio [Gutachter] Dappiaggi. "Mode decomposition and Fourier analysis of physical fields in homogeneous cosmology / Zhirayr Avetisyan ; Gutachter: Rainer Verch, Claudio Dappiaggi ; Betreuer: Rainer Verch." Leipzig : Universitätsbibliothek Leipzig, 2013. http://d-nb.info/1238366201/34.

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12

Zhang, Yirui S. M. Massachusetts Institute of Technology. "Understanding the pathway and mechanism of electrolyte decomposition on metal oxide surfaces in Li-ion batteries by in situ Fourier Transform Infrared Spectroscopy." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122227.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 69-75).<br>Understanding (electro)chemical reactions at the electrode-electrolyte interface (EEI) is crucial to promote the cycle life of lithium-ion batteries. In situ studies of EEI can provide new insights into reaction intermediates and soluble species not accessible by ex situ characterization of electrode surfaces. In this study, we developed an in situ Fourier Transform infrared spectroscopy (FTIR) method t

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13

Ditch, Benjamin D. "Thermal decomposition products testing with 1,1,1,2,2,4,5,5,5 nonafluoro-4-trifluoromethyl pentan-3-one (C6 F-ketone) during fire extinguishing." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0106103-152708.

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14

Koski, Antti E. "Rapid frequency estimation." Worcester, Mass. : Worcester Polytechnic Institute, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-032806-165036/.

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Thesis (M.S.)--Worcester Polytechnic Institute.<br>Keywords: DSS; ECM; SVD; Singular Value Decomposition; rapid frequency estimation; frequency estimation. Includes bibliographical references (leaves 174-177).

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15

Johar, Jasmeet Singh. "An experimental investigation of the urea-water decomposition and selective catalytic reduction (SCR) of nitric oxides with urea using V2O5-WO3-TiO2 catalyst." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2595.

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Two flow reactor studies, using an electrically heated laminar flow reactor over Vanadia based (V2O5-WO3/TiO2) honeycomb catalyst, were performed at 1 atm pressure and various temperatures. The experiments were conducted using simulated exhaust gas compositions for different exhaust gases. A quartz tube was used in order to establish inert conditions inside the reactor. The experiments utilized a Fourier transform infrared (FTIR) spectrometer in order to perform both qualitative and quantitative analysis of the reaction products. Urea-water solution decomposition was investigated over V2O5-WO3

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16

COSTES, DENIS. "Etude de la transmission d'une onde ultrasonore bornee en espace et en temps a travers des interfaces planes par la methode de decomposition de fourier." Paris 6, 1996. http://www.theses.fr/1996PA066099.

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Les travaux ont porte sur une methode de calcul de champs ultrasonores bornes en espace et en temps a travers une ou plusieurs interfaces refractantes. La theorie utilisee consiste en une decomposition du faisceau acoustique par la methode integrale de fourier portant sur les variables spatiales et temporelles. Une etude theorique et bibliographique est d'abord presentee, reprenant les differents developpements qui menent a l'expression integrale du champ acoustique. Plusieurs methodes de description de la repartition acoustique sont identifiees. A la suite de cela, une methode de numerique, v

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17

Xiao, Ying. "New tools for unsupervised learning." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52995.

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In an unsupervised learning problem, one is given an unlabelled dataset and hopes to find some hidden structure; the prototypical example is clustering similar data. Such problems often arise in machine learning and statistics, but also in signal processing, theoretical computer science, and any number of quantitative scientific fields. The distinguishing feature of unsupervised learning is that there are no privileged variables or labels which are particularly informative, and thus the greatest challenge is often to differentiate between what is relevant or irrelevant in any particular datase

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18

Hauser, Michael A., and Wolfgang Hörmann. "The Generation of Stationary Gaussian Time Series." Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 1997. http://epub.wu.ac.at/1630/1/document.pdf.

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Three different algorithms for the generation of stationary Gaussian time series with given autocorrelation function are presented in this paper. The algorithms have already been suggested in the literature but are not well known and have never been compared before. Interrelations between the different methods, advantages and disadvantages with respect to speed and memory requirements and the range of autocorrelation functions for which the different methods are stable are discussed. The time-complexity of the algorithms and the comparisons of their implementations show that the method twice u

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19

Corteville, Dominique Maurice Richard [Verfasser], and Lothar [Akademischer Betreuer] Schad. "Optimization of the measurement sequence used for functional Fourier Decomposition Magnetic Resonance Imaging of the human lung at 1.5 Tesla / Dominique Maurice Richard Corteville ; Betreuer: Lothar Schad." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180500709/34.

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Corteville, Dominique [Verfasser], and Lothar [Akademischer Betreuer] Schad. "Optimization of the measurement sequence used for functional Fourier Decomposition Magnetic Resonance Imaging of the human lung at 1.5 Tesla / Dominique Maurice Richard Corteville ; Betreuer: Lothar Schad." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-191692.

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21

Elias, Rana. "Pour l'évaluation des modifications des caractéristiques d'un système dynamique." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1107/document.

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L'évaluation des modifications des caractéristiques d'un système dynamique non-stationnaire est étudiée suivant les modifications des paramètres modaux. Pour cela, nous étudions en premier l'obtention de ces paramètres, à l'aide des méthodes d'identification à partir des réponses vibratoires mesurées. Trois méthodes d'identification sont étudiées: la méthode de Décomposition Orthogonale Propre (POD), la méthode de Décomposition en Valeurs Singulières (SVD) et la méthode de Décomposition Orthogonale Régularisée (SOD). Ensuite, trois étapes sont considérées pour suivre les changements de masse d

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22

Michael, Simon. "A Comparison of Data Transformations in Image Denoising." Thesis, Uppsala universitet, Statistiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-375715.

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The study of signal processing has wide applications, such as in hi-fi audio, television, voice recognition and many other areas. Signals are rarely observed without noise, which obstruct our analysis of signals. Hence, it is of great interest to study the detection, approximation and removal of noise. In this thesis we compare two methods for image denoising. The methods are each based on a data transformation. Specifically, Fourier Transform and Singular Value Decomposition are utilized in respective methods and compared on grayscale images. The comparison is based on the visual quality of

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23

Dohnal, Matěj. "Paralelizace ultrazvukových simulací s využitím lokální Fourierovy dekompozice." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-234949.

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This document introduces a brand new method of the 1D, 2D and 3D decomposition with the use of local Fourier basis, its implementation and comparison with the currently used global 1D domain decomposition. The new method was designed, implemented and tested primarily for future use in the simulation software called The k-Wave toolbox, but it can be applied in many other spectral methods. Compared to the global 1D domain decomposition, the Local Fourier decomposition is up to 3 times faster and more efficient thanks to lower inter-process communication, however it is a little inaccurate. The fi

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24

Van, Huyssteen Rudolph Hendrik. "Comparative evaluation of video watermarking techniques in the uncompressed domain." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71842.

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Thesis (MScEng)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Electronic watermarking is a method whereby information can be imperceptibly embedded into electronic media, while ideally being robust against common signal manipulations and intentional attacks to remove the embedded watermark. This study evaluates the characteristics of uncompressed video watermarking techniques in terms of visual characteristics, computational complexity and robustness against attacks and signal manipulations. The foundations of video watermarking are reviewed, followed by a survey of existing vide

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25

Voskrebenzev, Andreas [Verfasser], Jens [Akademischer Betreuer] Vogel-Claussen, and Lilli [Akademischer Betreuer] Geworski. "Magnetic resonance imaging of the regional lung function with Fourier decomposition : method development, reproducibility assessment and application in patients after double lung transplant / Andreas Voskrebenzev ; Akademische Betreuer: Jens Vogel-Claussen, Lilli Geworski ; Diagnostische und Interventionelle Radiologie." Hannover : Bibliothek der Medizinischen Hochschule Hannover, 2018. http://d-nb.info/1159903506/34.

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26

Chiu, Jiawei. "Matrix probing, skeleton decompositions, and sparse Fourier transform." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83691.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Department of Mathematics, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 163-168).<br>In this thesis, we present three different randomized algorithms that help to solve matrices, compute low rank approximations and perform the Fast Fourier Transform. Matrix probing and its conditioning When a matrix A with n columns is known to be well approximated by a linear combination of basis matrices B1,... , Bp, we can apply A to a random vector and solve a linear system to recover this linear combina

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27

Oygur, Ozgur Sinan. "Semi Analytical Study Of Stress And Deformation Analysis Of Anisotropic Shells Of Revolution Including First Order Transverse Shear Deformation." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609870/index.pdf.

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In this study, anisotropic shells of revolution subject to symmetric and unsymmetrical static loads are analysed. In derivation of governing equations to be used in the solution, first order transverse shear effects are included in the formulation. The governing equations can be listed as kinematic equations, constitutive equations, and equations of motion. The equations of motion are derived from Hamilton&rsquo<br>s principle, the constitutive equations are developed under the assumptions of the classical lamination theory and the kinematic equations are based on the Reissner-Naghdi linear sh

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28

Yin, Zhi. "Espaces de Hardy en probabilités et analyse harmonique quantiques." Phd thesis, Université de Franche-Comté, 2012. http://tel.archives-ouvertes.fr/tel-00838496.

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Cette thèse présente quelques résultats de la théorie des probabilités quantiques et de l'analyse harmonique à valeurs operateurs. La thèse est composée des trois parties.Dans la première partie, on démontre la décomposition atomique des espaces de Hardy de martingales non commutatives. On identifie aussi les interpolés complexes et réels entre les versions conditionnelles des espaces de Hardy et BMO de martingales non commutatives.La seconde partie est consacrée à l'étude des espaces de Hardy à valeurs opérateursvia la méthode d'ondellettes. Cette approche est similaire à celle du cas des mar

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Lund, Darren Scott. "Fourier Decompositions of Graphs with Symmetries and Equitable Partitions." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/8925.

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We show that equitable partitions, which are generalizations of graph symmetries, and Fourier transforms are fundamentally related. For a partition of a graph's vertices we define a Fourier similarity transform of the graph's adjacency matrix built from the matrices used to carryout discrete Fourier transformations. We show that the matrix (graph) decomposes into a number of smaller matrices (graphs) under this transformation if and only if the partition is an equitable partition. To extend this result to directed graphs we define two new types of equitable partitions, equitable receiving and

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30

Dufoyer, Adeline. "Signification physique et hydrologique de l'information spectrale contenue dans le signal hydrodynamique à l'exutoire des systèmes karstiques. Links between karst hydrogeological properties and statistical characteristics of spring discharge time series : a theoretical study." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR147.

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À l’échelle mondiale, des enjeux socio-économiques majeurs reposent sur les systèmes karstiques, tant pour l’alimentation en eau potable des populations que pour l’exploitation des gisements auxquels ils sont associés. Ces systèmes sont définis, par De Marsily (1984), comme des milieux dans lesquels « l’hétérogénéité atteint son paroxysme » : les modelés physiques caractérisant le karst sont particulièrement variés et les réponses hydrodynamiques sont indéniablement complexes et non-linéaires. Aujourd’hui, il n’est toujours pas possible de définir précisément l’organisation des hétérogénéités

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31

Nikl, Vojtěch. "Paralelizace ultrazvukových simulací pomocí 2D dekompozice." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2014. http://www.nusl.cz/ntk/nusl-413351.

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This thesis is a part of the k-Wave project, which is a toolbox for the simulation and reconstruction of acoustic wave felds and one of its main contributions is the planning of focused ultrasound surgeries (HIFU). One simulation can take tens of hours and about 60% of the simulation time is taken by the calculation of the 3D Fast Fourier transforms. Up until now the 3D FFT has been calculated purely by the FFTW library and its 1D decomposition, whose major limitation is the maximum number of employable cores. Therefore we introduce a new approach, called the 2D hybrid decomposition of the 3D

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KOMATSU, LUIZ G. H. "Estudo comparativo de nanocompósitos de polipropileno modificado sob condições de envelhecimento ambiental e acelerado." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26380.

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Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T12:34:18Z No. of bitstreams: 0<br>Made available in DSpace on 2016-06-22T12:34:18Z (GMT). No. of bitstreams: 0<br>Dissertação (Mestrado em Tecnologia Nuclear)<br>IPEN/D<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Jízdný, Martin. "Vlastní tvary vírového proudění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229641.

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This thesis deals with study of dynamics of the swirling flow. The swirling flow occurs frequently in hydraulic machinery (e.g., vortex rope in draft tube of the hydraulic turbine) and often influences operation of these machines. For this reason, sufficient knowledge regarding this characteristic flow is necessary for subsequent improvement of hydraulic machines. The theoretical part of this thesis contains description of flow instabilities and their manifestations, notably Kármán vortex street and vortex rope. In the next part, two methods are applied to these two transient flows in order to

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34

Gaudard, Eric. "Développement d'outils pour l'analyse de champs aéroacoustiques à l'origine du bruit dans un habitacle automobile." Electronic Thesis or Diss., Paris 6, 2014. http://www.theses.fr/2014PA066717.

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Cette étude a pour objet le développement d’outils d’analyse de champs aéroacoustiques. L’intérêt d’un tel travail est d’améliorer la compréhension des phénomènes physiques à l’origine du bruit aéroacoustique perçu dans un habitacle automobile. Une méthode de suivi d’onde basée sur une analyse de sensibilité est tout d’abord présentée et appliquée dans différentes configurations. Les intérêts et les limites de cet outil sont précisés. Ensuite, trois méthodes de décomposition sont étudiées : la Transformée de Fourier Discrète, la Décomposition Orthogonale aux valeurs Propres et la Décomposition

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35

Gannac, Yves. "Alliages Fe-6,5%Si élaborés par solidification rapide sous atmosphère controlée : microstructure, propriétés magnétiques et comparaison avec des alliages Fe-Si industriels." Toulouse, INSA, 1992. http://www.theses.fr/1992ISAT0015.

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La realisation d'un dispositif de solidification rapide sous atmosphere controlee permet l'elaboration de rubans fer-silicium avec un exces de silicium (6,5% masse) dont l'etat de surface est ameliore par rapport a celui de rubans trempes a l'air. Un bon controle de parametres de coulee conduit a l'elaboration de rubans de qualite et geometrie correctes et reproductibles. Les proprietes magnetiques a faible frequence (0-50 hz), placent ces alliages a un niveau legerement inferieur a celui des alliages industriels a grains orientes, mais nettement au-dessus des alliages a grains non orientes qu

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Tuleja, Peter. "Využití Hilbert Huangovy transformace pro analýzu nestacionárních signálů z fyzikálních experimentů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220614.

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This paper discusses the possible use of Hilbert-Huang transform to analyze the data obtained from physical experiments. Specifically for the analysis of acoustic emission in the form of acoustic shock. The introductory section explains the concept of acoustic emission and its detection process. Subsequently are discussed methods for signal analysis in time-frequency domain. Specifically, short-term Fourier transform, Wavelet transform, Hilbert transform and Hilbert-Huang transform. The final part contains the proposed method for measuring the performance and accuracy of different approaches.

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Hargis, Brent H. "Analysis of Long-Term Utah Temperature Trends Using Hilbert-Haung Transforms." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5490.

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We analyzed long-term temperature trends in Utah using a relatively new signal processing method called Empirical Mode Decomposition (EMD). We evaluated the available weather records in Utah and selected 52 stations, which had records longer than 60 years, for analysis. We analyzed daily temperature data, both minimum and maximums, using the EMD method that decomposes non-stationary data (data with a trend) into periodic components and the underlying trend. Most decomposition algorithms require stationary data (no trend) with constant periods and temperature data do not meet these constraints.

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MARINI, FRANCESCO. "Wave induced hydro and morpho-dynamics around a single slender pile: experimental and numerical analysis." Doctoral thesis, Università Politecnica delle Marche, 2020. http://hdl.handle.net/11566/274622.

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Negli ultimi anni, la presenza in mare di strutture fondate su pali, come piattaforme petrolifere e turbine eoliche offshore, sta diventando sempre più importante. Per questa ragione, guadagna sempre più importanza l’analisi di possibili criticismi e incertezze nella loro progettazione. L’obiettivo di questa tesi è lo studio dell’idro e della morfodinamica indotta da onde regolari e non su un palo di piccolo diametro attraverso una modellazione fisica e numerica. Questa tesi vuole quindi dare un contributo per la comprensione di tali processi fisici. In particolare, si vogliono fornire degli s

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Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.

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Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions

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Kasaei, Shohreh. "Fingerprint analysis using wavelet transform with application to compression and feature extraction." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36053/7/36053_Digitised_Thesis.pdf.

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The main goal of this research is to design an efficient compression al~ gorithm for fingerprint images. The wavelet transform technique is the principal tool used to reduce interpixel redundancies and to obtain a parsimonious representation for these images. A specific fixed decomposition structure is designed to be used by the wavelet packet in order to save on the computation, transmission, and storage costs. This decomposition structure is based on analysis of information packing performance of several decompositions, two-dimensional power spectral density, effect of each frequency

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Xi, Yunfei. "Synthesis, characterisation and application of organoclays." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16483/1/Yunfei_Xi_Thesis.pdf.

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This thesis focuses on the synthesis and characterisation of organoclays. X-ray diffraction has been used to study the changes in the basal spacings of montmorillonite clay and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. Three different molecular environments for surfactant octadecyltrimethylammonium bromide (ODTMA) within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. High-resolution thermogravimetric analysis (HRTG) shows that the thermal de

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Xi, Yunfei. "Synthesis, characterisation and application of organoclays." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16483/.

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This thesis focuses on the synthesis and characterisation of organoclays. X-ray diffraction has been used to study the changes in the basal spacings of montmorillonite clay and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. Three different molecular environments for surfactant octadecyltrimethylammonium bromide (ODTMA) within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. High-resolution thermogravimetric analysis (HRTG) shows that the thermal de

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Al, Takash Ahmad. "Development of Numerical Methods to Accelerate the Prediction of the Behavior of Multiphysics under Cyclic Loading." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2018. http://www.theses.fr/2018ESMA0014/document.

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La réduction du temps de calcul lors de la résolution de problèmes d’évolution dans le cadre du calcul de structure constitue un enjeu majeur pour, par exemple, la mise en place de critères de rupture des pièces dans le secteur de l’aéronautique et de l’automobile. En particulier, la prédiction du cycle stabilisé des polymères sollicités sous chargement cyclique nécessite de résoudre un problème thermo-viscoélastique à grand nombre de cycles. La présence de différentes échelles de temps telles que le temps de relaxation (viscosité), le temps caractéristique associé au problème thermique et le

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Cao, Hongmei. "Problémes bien-posés et étude qualitative pour des équations cinétiques et des équations dissipatives." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR044/document.

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Dans cette thèse, nous étudions certaines équations différentielles partielles avec mécanisme dissipatif, telles que l'équation de Boltzmann, l'équation de Landau et certains systèmes hyperboliques symétriques avec type de dissipation. L'existence globale de solutions ou les taux de dégradation optimaux des solutions pour ces systèmes sont envisagées dans les espaces de Sobolev ou de Besov. Les propriétés de lissage des solutions sont également étudiées. Dans cette thèse, nous prouvons principalement les quatre suivants résultats, voir les chapitres 3-6 pour plus de détails. Pour le premier ré

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Ayvazyan, Vigen. "Etude de champs de température séparables avec une double décomposition en valeurs singulières : quelques applications à la caractérisation des propriétés thermophysiques des matérieux et au contrôle non destructif." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14671/document.

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La thermographie infrarouge est une méthode largement employée pour la caractérisation des propriétés thermophysiques des matériaux. L’avènement des diodes laser pratiques, peu onéreuses et aux multiples caractéristiques, étendent les possibilités métrologiques des caméras infrarouges et mettent à disposition un ensemble de nouveaux outils puissants pour la caractérisation thermique et le contrôle non desturctif. Cependant, un lot de nouvelles difficultés doit être surmonté, comme le traitement d’une grande quantité de données bruitées et la faible sensibilité de ces données aux paramètres rec

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Avetisyan, Zhirayr. "Mode decomposition and Fourier analysis of physical fields in homogeneous cosmology." Doctoral thesis, 2012. https://ul.qucosa.de/id/qucosa%3A11872.

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In this work the methods of mode decomposition and Fourier analysis of quantum fields on curved spacetimes previously available mainly for the scalar fields on Friedman-Robertson-Walker spacetimes are extended to arbitrary vector fields on general spatially homogeneous spacetimes. This is done by developing a rigorous unified framework which incorporates mode decomposition, harmonic analysis and Fourier analysis. Explicit constructions are performed for a variety of situations arising in homogeneous cosmology. A number of results concerning classical and quantum fields known for very restricte

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Hoang, Thai Duy. "Fourier and Variational Based Approaches for Fingerprint Segmentation." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0022-5FEF-2.

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Goldstein, Hilton. "The investigation into an algorithm based on wavelet basis functions for the spatial and frequency decomposition of arbitrary signals." Thesis, 1994. http://hdl.handle.net/10413/7347.

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The research was directed toward the viability of an O(n) algorithm which could decompose an arbitrary signal (sound, vibration etc.) into its time-frequency space. The well known Fourier Transform uses sine and cosine functions (having infinite support on t) as orthonormal basis functions to decompose a signal i(t) in the time domain to F(w) in the frequency . domain, where the Fourier coefficients F(w) are the contributions of each frequency in the original signal. Due to the non-local support of these basis functions, a signal containing a sharp localised transient does not have localised c

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Bettadapura, Raghu Prasad Radhakrishna. "Flexible fitting in 3D EM." 2012. http://hdl.handle.net/2152/19478.

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In flexible fitting, the high-resolution crystal structure of a molecule is deformed to optimize its position with respect to a low-resolution density map. Solving the flexible fitting problem entails answering the following questions: (A) How can the crystal structure be deformed? (B) How can the term "optimum" be defined? and (C) How can the optimization problem be solved? In this dissertation, we answer the above questions in reverse order. (C) We develop PFCorr, a non-uniform SO(3)-Fourier-based tool to efficiently conduct rigid-body correlations over arbitrary subsets of the space of ri

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Myronova, Mariia. "Applications of finite reflection groups in Fourier analysis and symmetry breaking of polytopes." Thesis, 2021. http://hdl.handle.net/1866/25600.

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Cette thèse présente une étude des applications des groupes de réflexion finis aux problems liés aux réseaux bidimensionnels et aux polytopes tridimensionnels. Plusieurs familles de fonctions orbitales, appelées fonctions orbitales de Weyl, sont associées aux groupes de réflexion cristallographique. Les propriétés exceptionnelles de ces fonctions, telles que l’orthogonalité continue et discrète, permettent une analyse de type Fourier sur le domaine fondamental d’un groupe de Weyl affine correspondant. Dans cette considération, les fonctions d’orbite de Weyl constituent des outils efficaces pou

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