Дисертації: "Sum Fourier"

1

Müllner, Clemens. "Exponential sum estimates and Fourier analytic methods for digitally based dynamical systems." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0042/document.

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La présente thèse a été fortement influencée par deux conjectures, l'une de Gelfond et l'autre de Sarnak.En 1968, Gelfond a prouvé que la somme des chiffres modulo m est asymtotiquement équirépartie dans des progressions arithmétiques, et il a formulé trois problèmes nouveaux.Le deuxième et le troisième problèmes traitent des sommes des chiffres pour les nombres premiers et les suites polynomiales.En ce qui concerne les nombres premiers et les carrés, Mauduit et Rivat ont résolu ces problèmes en 2010 et 2009, respectivement.Drmota, Mauduit et Rivat ont réussi généraliser le résultat concernant la suite des sommes des chiffres des carrés.Ils ont démontré que chaque bloc apparaît asymptotiquement avec la même fréquence.Selon la conjecture de Sarnak, il n'y a pas de corrélation entre la fonction de Möbius et des fonctions simples.La présente thèse traite de la répartition de suites automatiques le long de sous-suites particulières ainsi que d'autres propriétés de suites automatiques.Selon l'un des résultats principaux du présent travail, toutes les suites automatiques vérifient la conjecture de Sarnak.Moyennant une approche légèrement modifiée, nous traitons également la répartition de suites automatiques le long de la suite des nombres premiers.Dans le cadre du traitement de suites automatiques générales, nous avons mis au point une nouvelle structure destinée aux automates finisdéterministes ouvrant une vision nouvelle pour les automates et/ou les suites automatiques.Nous étendons les résultat de Drmota, Mauduit et Rivat concernant les suites digitales.Cette approche peut également être considérée comme une généralisation du troisième problème de Gelfond
The present dissertation was inspired by two conjectures, one by Gelfond and one of Sarnak.In 1968 Gelfond proved that the sum of digits modulo m is asymptotically equally distributed along arithmetic progressions.Furthermore, he stated three problems which are nowadays called Gelfond problems.The second and third questions are concerned with the sum of digits of prime numbers and polynomial subsequences.Mauduit and Rivat were able to solve these problems for primes and squares in 2010 and 2009 respectively.Drmota, Mauduit and Rivat generalized the result concerning the sequence of the sum of digits of squares.They showed that each block appears asymptotically equally frequently.Sarnak conjectured in 2010 that the Mobius function does not correlate with deterministic functions.This dissertation deals with the distribution of automatic sequences along special subsequences and other properties of automatic sequences.A main result of this thesis is that all automatic sequences satisfy the Sarnak conjecture.Through a slightly modified approach, we also deal with the distribution of automatic sequences along the subsequence of primes.In the course of the treatment of general automatic sequences, a new structure for deterministic finite automata is developed,which allows a new view for automata or automatic sequences.We extend the result of Drmota, Mauduit and Rivat to digital sequences.This is also a generalization of the third Gelfond problem

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2

Литвин, О. М., та О. Г. Литвин. "Оптимізація кількості експериментальних даних у методі обчислення коефіцієнтів Фур’є за допомогою проекцій". Thesis, Полтава: ПУЕТ, 2017. http://openarchive.nure.ua/handle/document/3813.

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Досліджується метод розв’язання задачі реконструкції зображень на основі використання скінченних сум Фур’є, запропонований автором Литвин О. М., в якому коефіцієнти Фур’є обчислюються за допомогою проекцій, що надходять з комп’ютерного томографа. Отримано співвідношення між порядком сум Фур’є, кількістю проекцій та точністю відновлення функції. Litvin O.M., Litvin O.G .Optimizing the number of experimental data in the method of calculating Fourier coefficients using projections.We study the method of solving the problem of image reconstruction based on the use of finite Fourier sums proposed by the author O.M. Litvin, where the Fourier coefficients are calculated using projections coming from the computer tomograph. Correlations between order Fourier sums, the number of projections and accurate restoration of function are given.

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3

Ravindran, Hari Alangat. "On Shifted Convolution Sums Involving the Fourier Coefficients of Theta Functions Attached to Quadratic Forms." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406039690.

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4

McGuire, John Andrew. "Femtosecond nonlinear spectroscopy at surfaces Second-harmonic probing of hole burning at the Si(111)7x7 surface and fourier-transform sum-frequency vibrational spectroscopy." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/836810-xRj01W/native/.

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Thesis (Ph.D.); Submitted to the University of California, Berkeley, CA (US); 24 Nov 2004.
Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--56751" McGuire, John Andrew. USDOE Director. Office of Science. Office of Basic Energy Sciences. Materials Science and Engineering Division (US) 11/24/2004. Report is also available in paper and microfiche from NTIS.

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5

Xu, Yangyi. "Frequentist-Bayesian Hybrid Tests in Semi-parametric and Non-parametric Models with Low/High-Dimensional Covariate." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/71285.

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We provide a Frequentist-Bayesian hybrid test statistic in this dissertation for two testing problems. The first one is to design a test for the significant differences between non-parametric functions and the second one is to design a test allowing any departure of predictors of high dimensional X from constant. The implementation is also given in construction of the proposal test statistics for both problems. For the first testing problem, we consider the statistical difference among massive outcomes or signals to be of interest in many diverse fields including neurophysiology, imaging, engineering, and other related fields. However, such data often have nonlinear system, including to row/column patterns, having non-normal distribution, and other hard-to-identifying internal relationship, which lead to difficulties in testing the significance in difference between them for both unknown relationship and high-dimensionality. In this dissertation, we propose an Adaptive Bayes Sum Test capable of testing the significance between two nonlinear system basing on universal non-parametric mathematical decomposition/smoothing components. Our approach is developed from adapting the Bayes sum test statistic by Hart (2009). Any internal pattern is treated through Fourier transformation. Resampling techniques are applied to construct the empirical distribution of test statistic to reduce the effect of non-normal distribution. A simulation study suggests our approach performs better than the alternative method, the Adaptive Neyman Test by Fan and Lin (1998). The usefulness of our approach is demonstrated with an application in the identification of electronic chips as well as an application to test the change of pattern of precipitations. For the second testing problem, currently numerous statistical methods have been developed for analyzing high-dimensional data. These methods mainly focus on variable selection approach, but are limited for purpose of testing with high-dimensional data, and often are required to have explicit derivative likelihood functions. In this dissertation, we propose ``Hybrid Omnibus Test'' for high-dimensional data testing purpose with much less requirements. Our Hybrid Omnibus Test is developed under semi-parametric framework where likelihood function is no longer necessary. Our Hybrid Omnibus Test is a version of Freqentist-Bayesian hybrid score-type test for a functional generalized partial linear single index model, which has link being functional of predictors through a generalized partially linear single index. We propose an efficient score based on estimating equation to the mathematical difficulty in likelihood derivation and construct our Hybrid Omnibus Test. We compare our approach with a empirical likelihood ratio test and Bayesian inference based on Bayes factor using simulation study in terms of false positive rate and true positive rate. Our simulation results suggest that our approach outperforms in terms of false positive rate, true positive rate, and computation cost in high-dimensional case and low-dimensional case. The advantage of our approach is also demonstrated by published biological results with application to a genetic pathway data of type II diabetes.
Ph. D.

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6

Li, Jialun. "Harmonic analysis of stationary measures." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0311/document.

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Soit μ une mesure de probabilité borélienne sur SL m+1 (R) tel que le sous-groupe engendré par le support de μ est Zariski dense. Soit V une représentation irréductible de dimension finie de SL m+1 (R). D’après un théorème de Furstenberg, il existe une unique mesure μ-stationnaire sur PV et nous nous somme intéressés à la décroissance de Fourier de cette mesure. Le résultat principal de cette thèse est que la transformée de Fourier de la mesure stationnaire a une décroissance polynomiale. À partir de ce résultat, nous obtenons un trou spectral de l’opérateur de transfert, dont les propriétés nous permettent d’établir un terme d’erreur exponentiel pour le théorème de renouvellement dans le cadre des produits de matrices aléatoires. L’ingrédient essentiel est une propriété de décroissance de Fourier des convolutions multiplicatives de mesures sur R n , qui est une généralisation d’un théorème de Bourgain en dimension 1. Nous établissons cet ingrédient en utilisant un estimée somme produit de He et de Saxcé.Dans la dernière partie, nous généralisons un résultat de Lax et Phillips et un résultat de Hamenstädt sur la finitude des petites valeurs propres de l’opérateur de Laplace sur les variétés hyperboliques géométriquement finies
Let μ be a Borel probability measure on SL m+1 (R), whose support generates a Zariski dense subgroup. Let V be a finite dimensional irreducible linear representation of SL m+1 (R). A theorem of Furstenberg says that there exists a unique μ-stationary probability measure on PV and we are interested in the Fourier decay of the stationary measure. The main result of the thesis is that the Fourier transform of the stationary measure has a power decay. From this result, we obtain a spectral gap of the transfer operator, whose properties allow us to establish an exponential error term for the renewal theorem in the context of products of random matrices. A key technical ingredient for the proof is a Fourier decay of multiplicative convolutions of measures on R n , which is a generalisation of Bourgain’s theorem on dimension 1. We establish this result by using a sum-product estimate due to He-de Saxcé. In the last part, we generalize a result of Lax-Phillips and a result of Hamenstädt on the finiteness of small eigenvalues of the Laplace operator on geometrically finite hyperbolic manifolds

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7

Abolarin, David. "Non-invasive Estimation of Blood Pressure using Harmonic Components of Oscillometric Pulses." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34114.

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This research presents a pulse-by-pulse analysis of Oscillometric blood pressure waveform at systolic, diastolic and mean arterial pressure points. Using a mathematical optimization technique, pulses are characterized into component harmonic by minimizing the least square error. The results at the important pressure points are analyzed and compared for different subject using different waveform extraction techniques. Blood pressure is estimated using the harmonic parameters. The approach studies changes in the parameters as oscillometric blood pressure recording is done. 8 harmonic parameters are obtained from the pulse characterization and are used to estimate Systolic arterial Blood Pressure, Mean arterial Blood Pressure, and Diastolic arterial Blood Pressure. The estimates are compared with our reference value to determine which has the best agreement. The proposed method is further compared with Maximum Amplitude Algorithm and Pulse Morphology Algorithm. The effect of oscillometric waveform extraction methods on the proposed method is observed. The experiment established the fact that the extraction technique can alter the shape of oscillometric pulses. The methods were compared and it was observed that the used extraction methods did not make any significant difference on the accuracy, using this technique.

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8

Del, Gatto Davide. "Analisi di Fourier sui Gruppi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18784/.

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La tesi riguarda la generalizzazione della trasformata di Fourier per funzioni di L^1(G), dove G è un gruppo topologico localmente compatto e di Hausdroff. L'obbiettivo è di mostrare che i risultati noti per la trasformata di Fourier (come il Teorema di Inversione, il Teorema di Plancherel, ecc...) sono validi anche in questo caso e di presentare alcuni risultati classici di analisi armonica astratta nel caso di gruppi abeliani come il Teorema di Dualità di Pontryagin.

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9

Noorizadeh, Sahand. "SLM-based Fourier Differential Interference Contrast Microscopy." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/2011.

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Optical phase microscopy provides a view of objects that have minimal to no effect on the detected intensity of light that are unobservable by standard microscopy techniques. Since its inception just over 60 years ago that gave us a vision to an unseen world and earned Frits Zernike the Nobel prize in physics in 1953, phase microscopy has evolved to find various applications in biological cell imaging, crystallography, semiconductor failure analysis, and more. Two common and commercially available techniques are phase contrast and differential interference contrast (DIC). In phase contrast method, a large portion of the unscattered light that accounts for the majority of the light passing unaffected through a transparent medium is blocked to allow the scattered light due to the object to be observed with higher contrast. DIC is a self-referenced interferometer that transduces phase variation to intensity variation. While being established as fundamental tools in many scientific and engineering disciplines, the traditional implementation of these techniques lacks the ability to provide the means for quantitative and repeatable measurement without an extensive and cumbersome calibration. The rapidly growing fields in modern biology meteorology and nano-technology have emphasized the demand for a more robust and convenient quantitative phase microscopy. The recent emergence of modern optical devices such as high resolution programmable spatial light modulators (SLM) has enabled a multitude of research activities over the past decade to reinvent phase microscopy in unconventional ways. This work is concerned with an implementation of a DIC microscope containing a 4-f system at its core with a programmable SLM placed at the frequency plane of the imaging system that allows for employing Fourier pair transforms for wavefront manipulation. This configuration of microscope provides a convenient way to perform both wavefront shearing with quantifiable arbitrary shear amount and direction as well as phase stepping interferometry by programming the SLM with a series of numerically generated patterns and digitally capturing interferograms for each step which are then used to calculate the objects phase gradient map. Wavefront shearing is performed by generating a pattern for the SLM where two phase ramp patterns with opposite slopes are interleaved through a random selection process with uniform distribution in order to mimic the simultaneous presence of the ramps on the same plane. The theoretical treatment accompanied by simulations and experimental results and discussion are presented in this work.

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10

Potts, Daniel, and Manfred Tasche. "Parameter estimation for nonincreasing exponential sums by Prony-like methods." Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-86476.

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For noiseless sampled data, we describe the close connections between Prony--like methods, namely the classical Prony method, the matrix pencil method and the ESPRIT method. Further we present a new efficient algorithm of matrix pencil factorization based on QR decomposition of a rectangular Hankel matrix. The algorithms of parameter estimation are also applied to sparse Fourier approximation and nonlinear approximation.

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11

Marquezino, Franklin de Lima. "A transformada de Fourier quântica aproximada e sua simulação." Laboratório Nacional de Computação Científica, 2006. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=1.

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A Computação Quântica é uma área de pesquisa científica onde a teoria da Mecânica Quântica é usada para descrever um conceito mais geral que o da Máquina Universal de Turing clássica. esta abordagem permite o desenvolvimento de algoritmos que podem ser consideravelmente mais rápidos que suas contrapartidas clássicas. Todos os algoritmos quânticos conhecidos até hoje que são exponencialmente mais rápidos que seus correspondentes clássicos utilizam a transformada de Fourier Quântica (QFT) em alguma parte. Nesta dissertação, as versões exata e aproximada da QFT são construídas usando uma abordagem que generaliza o resultado fundamental de Coppersmith. O processo inicia com a representação matricial genérica da Transformada de Fourier Rápida (FFT) clássica, como descrita por Knuth, seguida por sua decomposição em termos de operadores quânticos universais. Tal decomposição também é alcançada por meio de uma abordagem recursiva. A simulação de computadores quânticos também é discutida. Experimentos computacionais são realizados com o objetivo de simular a QFT Aproximada sobre estados da base computacional e gatos de Schrödinger, e com diferentes níveis de aproximação. A qualidade das soluções e a complexidade computacional são estudadas, levando a resultados consistentes com a teoria.

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12

Peloux, Marius. "Nouveaux composants optiques pixellisés pour la correction visuelle : modélisation, optimisation et évaluation." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112202/document.

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Ce manuscrit de thèse traite de l’étude de verres ophtalmiques microstructurés et plus particulièrement pixellisés, ces derniers pouvant présenter un intérêt particulier en optique active pour la correction de la presbytie. Une étude théorique est proposée, permettant d’analyser les performances optiques d’une lentille pixellisée en termes de transport d’image et d’identifier les paramètres qui ont un impact direct sur ces performances. Après validation expérimentale des résultats obtenus, nous constatons puis expliquons l’effet sur l’observation d’une scène de l’excentrement de l’œil par rapport à la fonction de phase du verre. Nous étudions l’effet du repliement de phase inhérent aux limites des technologies de fabrication, qui vient ajouter un chromatisme axial aux défauts visuels engendrés par la pixellisation. Nous nous intéressons ensuite aux applications possibles de la pixellisation en optique passive. Nous prouvons que pour une application visée, des lentilles binaires non pixellisées, dont nous optimisons la qualité optique, conduisent à de meilleurs résultats que les lentilles pixellisées. L’impact sur l’acuité visuelle des phénomènes diffractifs parasites induits par la pixellisation est évalué au moyen d’un banc de mesure utilisant la simulation de certaines images telles qu’elles seraient vues au travers de verres ophtalmiques pixellisés. Enfin, nous menons une étude de l’aspect esthétique d’un verre pixellisé vu par un observateur externe, à partir de modèles de calcul hybrides mêlant optique géométrique et optique de Fourier
This thesis investigates microstructured and more particularly pixelated ophthalmic glasses, the latter raising some hope for the active correction of presbyopia. A theoretical study is developed for the analysis of the optical performances of a pixelated lens in terms of image transport and leads to the identification of the parameters which have an impact on these performances. After experimental validation of the results obtained, we note and then explain the effect on the observation of a scene of eye displacement with respect to the optical function of the eyeglass. We study the effect of phase wrapping, which is inherent in the limits of the technologies implied in the manufacturing process and adds an axial chromatism effect to the visual defects generated by pixelation. We are also interested in the potential applications of pixelation in the field of passive optics. We prove that for a given application, non pixelated binary lenses, the optical quality of which we optimize, lead to better results than pixelated lenses. The impact on visual acuity of the parasitic diffractive phenomena induced by pixelation is evaluated with an optical bench using the simulation of test images seen through pixelated lenses. Finally, we study the aesthetic aspect of a pixelated component as seen by an external observer, using hybrid calculation models based on both geometrical and Fourier optics

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13

Gaggioli, Filippo. "Uno studio analitico ed algebrico della trasformata di Radon ed alcune sue applicazioni." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11426/.

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Lo scopo di questa tesi si articola in tre punti. In primo luogo, ci proponiamo di definire, sia in ambito analitico che in un contesto più algebrico e geometrico, la trasformata di Radon, di discutere la possibilità di un'eventuale generalizzazione a spazi non euclidei, e di presentare le sue proprietà più caratteristiche. In secondo luogo vogliamo dimostrare, sfruttando un collegamento di questa con la trasformata di Fourier, che la trasformata di Radon è un'applicazione iniettiva tra spazi funzionali e che è dunque invertibile, per poi descrivere uno dei possibili metodi formali di inversione. Accenneremo anche alle problematiche che insorgono nell'utilizzare l'antitrasformata di Radon in situazioni reali, e alle relative soluzioni. Infine, concluderemo la trattazione con una breve ma, ottimisticamente, delucidatrice, introduzione ad alcuni esempi di applicazione della trasformata di Radon a vari ambiti fisici e matematici.

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14

MORIN, PHILIPPE. "Couplage chromatographie en phase dioxyde de carbone supercritique-spectrometrie infrarouge a transformee de fourier." Paris 6, 1988. http://www.theses.fr/1988PA066684.

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Etude de l'effet d'un modificateur organique, polaire, du dioxyde de carbone sur les donnees spectrales infra-rouge. Dans un deuxieme temps, l'effet de la phase stationnaire constituee par un copolymere est analyse

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15

ROBB, GARY MICHAEL. "ACIDITY CHARACTERIZATION OF ZEOLITES VIA COUPLED NH ₃ -STEPWISE TEMPERATURE PROGRAMMED DESORPTION AND FT-IR SPECTROSCOPY." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1021031631.

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16

Nicacio, Hayram. "Simulação e mapeamento de campos ultra-sonicos para caracterização de transdutores utilizando os metodos pontual e angular." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261850.

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Orientador : Eduardo Tavares Costa
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-02T10:25:57Z (GMT). No. of bitstreams: 1 Nicacio_Hayram_M.pdf: 3334926 bytes, checksum: 71c210c63dd7508651efef9a5c2f08b2 (MD5) Previous issue date: 2002
Mestrado

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17

Mazine, Alexandre. "La caractérisation de front d'onde dans un système de propagation à multi-illumination gérée par un SLM /." Paris : École nationale supérieure des télécommunications, 2006. http://catalogue.bnf.fr/ark:/12148/cb40208318n.

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18

Ford, William Paul. "Development of a Fourier Transform Far Infrared (FTFIR) Spectrometer to Characterize Broadband Transmission Properties of Common Materials in the Terahertz Region." Wright State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=wright1158508606.

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19

Petit, Jérôme. "Contrôle dimensionnel sub-micrométrique utilisant un appareil goniométrique bidimensionnel rapide." Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10211.

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Le travail présenté dans ce mémoire traite du contrôle dimensionnel optique pour la microélectronique et de l'adaptation d'un instrument à cette application. Le premier point clé de cette technique de métrologie est la possibilité de calculer le champ diffracté par une structure périodique, associé aux méthodes de calcul inverse. Le second point clés est la solution technologique adoptée pour mesurer la signature de diffiaction. Nous présentons ici un goniomètre bidimensionnel basé sur le principe de la Transformée de Fourier Optique. Cet appareil a été adapté à l'application métrologique et nous décrivons ici les différentes étapes qui nous permis aboutir. Ces étapes sont la description, la compréhension et l'analyse de l'instrument pour adapter les moyens numériques en notre possession aux spécificités du problème. Nous avons ensuite validé la fonction métrologique de l'instrument sur différentes structures comme des couches minces ou des réseaux. Nous avons comparé les résultats obtenus avec ceux obtenus en ellipsométrie spectroscopique ou en microscopie électronique à balayage. Nous avons pour chaque résultat, évalué les incertitudes et discuté de la validité du résultat. Enfin nous avons tiré parti des particularités de l'instrument pour réaliser des études plus qualitatives sur des structures plus complexes comme des lignes rugueuses ou des structures superposées
This work deals with Optical Critical Dimension metrology in microelectronics and with the use of an unusual tool for this application. The first keypoint of this metrology technique is the ability to calculate the scattered light pattern from a periodic structure and the second key point is the apparatus used to measure the diffracted pattern. We present here a goniometric instrument based on optical Fourier Transform. This equipment has been change for the metrological application and we describe in this text the different steps we had to deal with to achieve. These steps are the description of the measurement head, the understanding and the instrument analysis to adapt our numerical means to the problem needs. Then we validated the metrological function of the instrument on samples like opticallayers or gratings. We compare each etched structure measured with spectroscopic ellipsometry and Scanning Electron microscopy. Each result has been analyzed to evaluate accuracy on parameters. At last, we used instrument peculiarities to go through qualitative study of complex structures like line with roughness and overlay

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20

Thibodeau, Brian Michael. "A Framework for Cooperative Wideband Spectrum Sensing Using the Robust Fast Fourier Aliasing-based Sparse Transform." Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/389212.

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Анотація:

Electrical and Computer Engineering
M.S.E.E.
This research considers the problem of cooperatively identifying the active bands in a wideband spectrum using the sparse Fast Fourier Transform (sFFT). Existing research has focused primarily on Compressed Sensing (CS) and Multi-Coset (MC) sampling, but recent developments in the sFFT have shown that a sparsely occupied spectrum can be efficiently reconstructed using multiple co-prime analog-to-digital converters (ADC) that sample below the Nyquist rate. Specifically, this research utilizes the Robust Fast Fourier Aliasing-based Sparse Transform (R-FFAST) and extends this algorithm for use in cooperative wideband spectrum sensing (CWSS). Unlike previous approaches that implement the sFFT for spectrum sensing, the R-FFAST framework was developed and analyzed using the mutual coherence and the restricted isometry property (RIP) from CS theory. This leads to reliable support estimation in the presence of additive white Gaussian noise (AWGN) while mitigating the computational complexity of CS reconstruction algorithms. This research makes the following contributions. First, this research extends the signal model from single tones to multi-band signals with clustered support. Second, it shows that each stage in the R-FFAST front-end can be decomposed into individual nodes that form a fully distributed cooperative network. Lastly, this research empirically develops a constant false alarm rate (CFAR) detector that is used to identify the active frequency bins during the reconstruction process. The primary result of this research is showing that reliable spectrum detection is only possible when the average sampling rate of the cooperative network is greater than or equal to the sparsity of the spectrum. Simulation results are provided to demonstrate the effectiveness of the proposed framework and validate the findings of this research.
Temple University--Theses

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21

RAELE, MARCUS P. "Desenvolvimento de um sistema de tomografia por coerencia optica no dominio de Fourier sensivel a polarizacao e sua utilizacao na determinacao das matrizes de mueller." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9455.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Obinaju, Blessing. "Application of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to measure sub-lethal effects of potential mutagens." Thesis, Lancaster University, 2015. http://eprints.lancs.ac.uk/76562/.

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Techniques employed in vibrational spectroscopy monitor the vibrational modes of functional groups within biomolecules and enable a correlation between chemical information and histological structures. Interrogation of biological samples using infrared (IR) techniques generates spectrum with wavenumber-absorbance intensities specific to biomolecules within the sample. Methods are relatively non-destructive, and so samples can subsequently be analyzed by more conventional approaches. Analyses can be carried out ex vivo or in situ in living tissue, where a reference range of a designated normal state can be derived, and anything lying outside this range is potentially atypical. Computational approaches allow one to minimize within-category confounding factors. The application of vibrational spectroscopy in contaminant biomonitoring is a welcome development which has enabled the investigation of realtime contaminant exposure effects in the tissues of sentinels. IR techniques such as attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, was able to detect changes in various tissue samples exposed to varying levels of polycyclic aromatic hydrocarbons (PAHs). This technique discriminated between spatial and temporal variations in the interrogated tissues. Multivariate analysis was able to relate the alterations at various regions of the fingerprint, to PAH exposure and was able to detect PAH exposure in tissues from sites with no documented knowledge of contamination. ATR-FTIR detected PAH-induced changes in isolated nuclei of cultured cell populations in G0/G1 and S- phases of the cell cycle. Findings from the various projects affirm, that techniques involved in IR spectroscopy are highly sensitive to minimal changes in cell molecules. The ability to generate rapid results in real-time is valuable and the wide variety of sample types which can be interrogated using IR techniques makes it a suitable technique for environment biomonitoring.

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Vidal, Rosemeire Cardozo. "Algoritmo para estimar gravidade de DPOC através de sinais acústicos." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-11072017-151033/.

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O presente estudo tem como objetivo determinar se a gravidade da DPOC poderá ser estimada através da área do gráfico das intensidades sonoras dos sons respiratórios de pacientes com DPOC. O estudo realizado com 51 pacientes com DPOC leve, moderado, grave, muito grave e 7 indivíduos saudáveis não fumantes. Os sons respiratórios de cada participante, foram coletados através de estetoscópio adaptado com um mini microfone. O método compara as áreas das intensidades sonoras em função da frequência de pacientes de DPOC e indivíduos saudáveis. Neste contexto, para atender ao objetivo, um método foi proposto e testado baseado na combinação de técnicas de filtragem e TFTC, seguida de análise estatística, cálculo da média, desvio padrão e interpolação. Os resultados sugerem que a área do gráfico da variância da intensidade sonora em função da frequência diminui quando aumenta a gravidade da DPOC, exceto para os casos em que a bronquite crônica é predominante.
The present study aims to determine if the severity of COPD can be estimated through the chart area of the sound intensities of respiratory sounds in patients with COPD. The study included 51 patients with mild, moderate, severe, very severe COPD and 7 healthy non-smokers. The breathing sounds of each participant were collected through a stethoscope adapted with a mini microphone. The method compares the areas of intensity sonic densities as a function of the frequency of COPD patients and healthy individuals. In this context, to meet the objective, a method was proposed and tested based on the combination of filtering techniques and TFTC, followed by statistical analysis, calculation of the mean, standard deviation and interpolation. The results suggest that the area of the graph of frequency-frequency sound intensity variance decreases as the severity of COPD increases, except for cases where chronic bronchitis is predominant.

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Mazine, Alexandre. "La caractérisation de front d'onde dans un système de propagation à multi-illumination gérée par un SLM." Paris, ENST, 2006. http://www.theses.fr/2006ENST0003.

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La caractérisation de phase est la pierre angulaire de l'analyse de front d'onde. Devenant un secteur d'activité de plus en plus large, il nécessite de nouveaux moyens de contrôle plus efficaces, plus performants et meilleur marché. Les performances des techniques les plus utilisées dans ce domaine reposent en grande partie sur un équipement optique sophistiqué, alors que l'utilisation de la diffraction par propagation libre permet de simplifier au maximum le matériel et de reporter la charge aux algorithmes intelligents de traitement de données. L'objectif de ce travail est de mettre en valeur une technique d'analyse de front d'onde multivue ainsi que de construire une installation-prototype capable de caractériser les diverses cartes de phase. L'entité de l'étude réalisée consiste à proposer une méthode d'accès à la forme de la phase d'une onde inconnue à partir d'une séquence de ses figures de diffraction créées avec un modulateur spatial de lumière selon le principe des multiples ondes illuminantes. Pour contribuer au problème, un algorithme itératif de type IFTA (Iterative Fourier/Fresnel Transform Algorithm) dit la ``multi-illumination'' a été mis en oeuvre en deux versions qui sous-entendent soit les conditions de l'imagerie cohérente combinée avec une propagation libre, soit une double propagation de Fresnel/Fourier. Le fonctionnement de l'algorithme a été vérifié aussi bien en simulation numérique qu'au sein d'un montage optique experimental gouverné par un logiciel artisanal de pilotage. Les résultats obtenus démontrent sa convergence sûre et particulièrement rapide
Phase retrieval is a cornerstone of wavefront analysis, which is finding ever wider applications in many fields where it is met under two forms: wavefront reconstruction and surface analysis. Present techniques leave opportunities for novel methods: more powerful, more efficient and especially cheaper. Whereas the most popular techniques require sophisticated optical equipement, the use of a diffractive solution makes possible the use of low cost equipment combined with a powerful intelligent digital image-processing. The aim of this study is, on the one hand, to demonstrate the feasibility of a multiview principle dealing with phase retrieval of an unknown beam and on the other, to design an experimental setup that is able to determine the phase map from a small number of captured diffraction patterns. We propose a method, called here ``multi-illumination'', for extracting this phase-information with the aid of a spatial light modulator which produces a range of different illuminating beams. This method involves a digital image-processing based on the Iterative Fourier/Fresnel Transform Algorithm (IFTA) principle. Two versions are developped: the first using images grabbed in a coherent imaging system, the second works with diffraction patterns obtained in a double Fresnel/Fourier setup. The capacities of the algorithm are verified both in extensive digital simulations and in an experimental setup built up with a SLM and a CCD syncronously managed by a specifically developped software

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Fournier, Norman [Verfasser], Frank Stefan [Akademischer Betreuer] Tautz, and J. M. van [Akademischer Betreuer] Ruitenbeek. "STM-based quantum transport through molecular wires / Norman Fournier ; Frank Stefan Tautz, J. M. van Ruitenbeek." Aachen : Universitätsbibliothek der RWTH Aachen, 2015. http://d-nb.info/1128731118/34.

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Hebert, Gretchen N. "Detection and quantification of sub-micromolar concentrations of aqueous anions using infrared spectroscopy and mass spectrometry." Access citation, abstract and download form; downloadable file 11.28 Mb, 2004. http://wwwlib.umi.com/dissertations/fullcit/3131676.

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BARONI, Douglas Brandão. "Desenvolvimento de técnica ultra-sônica para medida de porosidade em pastilha de UO2." reponame:Repositório Institucional do IEN, 2008. http://hdl.handle.net/ien/567.

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A caracterização do combustível nuclear é de grande importância para garantir a eficiência e até mesmo a segurança nas usinas. Atualmente as técnicas utilizadas envolvem elevados custos com equipamentos, materiais e instalações de proteção radiológica, além disso, por serem destrutivas, impõem que a verificação das características deste material seja feita por amostragem. Neste trabalho desenvolveu-se uma técnica não destrutiva, que foi utilizada para medidas de porosidade em pastilhas de Alumina (Al2O3) que forneceu resultados precisos e rápidos. Tem-se o objetivo de que esta técnica possa ser utilizada na prática laboratorial para medidas em pastilhas de UO2, pois viabilizaria a inspeção de até 100% do combustível nuclear, garantindo maior controle das características do material utilizado, resultando em maior segurança, eficiência e economia. A inovação da técnica se deve ao fato de analisar o espectro de freqüência do pulso ultra-sônico, e não seu tempo de percurso no material, comumente utilizado. Neste trabalho foram utilizadas 40 pastilhas cerâmicas de alumina com valores de porosidade entre 5,09% e 37,30%. Um sistema de reconhecimento de sinais utilizando redes neurais artificiais possibilitou distinguir pastilhas com diferenças de porosidade de 0,04%. Observou-se também que esta técnica pode ser utilizada para diversos outros fins, como por exemplo, na determinação da fração de vazio em regime de escoamento bifásico, que é muito importante para garantir a eficiência e segurança de reatores nucleares.
The characterization of nuclear fuel is of great importance to guarantee the efficiency and even the safety in the power stations. At present, the techniques used implicate elevated costs with equipments, materials and installations of radiological protection. Besides, because of being destructive techniques, they impose that the checking of the characteristics of this material is done by sampling. In this work a not destructive technique was developed for measures of porosity in ceramic materials with efficiency and precision. The objective of this work is to this technique will be able to be used in practice laboratorial for measures in UO2 pellets, so it would become viable the inspection of up to 100% of the nuclear fuel, guaranteeing bigger control of the characteristics of the used material, turning in increasing safety, efficiency and economy. The innovation of the technique is due to the fact of analysing the specter of frequency of the ultrasonic wrist, and not his time of course in the material, frequently used. In this work 40 ceramic pellets of alumina were used with values of porosity between 5,09% and 37,30%. A system of recognition of signs using artificial neural networks made possible to distinguish pellets with differences of porosity of 0,04%. It was observed that this technique can be used for several others aims, for example, in the determination of the void fraction in regimen of two-phase flow, what is very important to guarantee the efficiency and safety of nuclear reactors.

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Novo, Junior José Eduardo Fornari 1966. "Transformações sonoras atraves de operações timbrais." [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261415.

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Orientador: Furio Damiani
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica
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Resumo: O som é abordado, pelo menos, por três ramos da ciências: a Acústica, a Fisiologia (da audição humana) e a Psicoacústica. A intersecção deste conhecimento, em linhas gerais, define: "oque", "por quê" e "como" escutamos. Dado isto.,torna-se possível dimensionar um sistema de processamento de sinais de audio que represente e manipule um som analógico (contínuo no tempo) com níveis de ruídos e perdas abaixo dos limites da percepção auditiva normal, que é chamado de "som de alta fidelidade" (HF). Devido ao crescente aumento da capacidade de memória e velocidade dos processadores digitais de sinais (DSPs), atualmente tornou-se factível projetar um sistema DSP para audio (ADSP), de alta fidelidade e que trabalhe em tempo-real, ou seja, um sistema ADSP cujo tempo de retardo entre o som de entrada e o de saída não seja percebido pela audição humana. A Psicoacústica trata das percepções subjetivas da audição humana em relação às grandezas da Acústica; como o loudness (a percepção subjetiva da intensidade sonora), o pitch (a percepção subjetiva da frequência sonora) e o quality, ou timbre (a percepção subjetiva das similaridades sonoras). No caso do timbre, sabe-se que este pode ser representado como: a variação contínua no tempo das intensidades dos harmônicos do espectro do som. Um sistema de ADSP HF que transforme o espectro em tempo-real, através de operações que possam ser continuamente re-parametrizados em tempo-real, pode manipular o timbre sonoro. O projeto de um sistema deste tipo é o objetivo deste trabalho. Este sistema trabalha com sons de entrada e saída analógicos. No entanto, o processamento é digital. Desse modo existe a necessidade de pre-processamento (filtragem e controle de nível) e conversão A/D e D/A adequados para garatir o desempenho HF do sistema. Os espectros do som discretizado de entrada são obtidos através do algoritmo rápido da transformada discreta de Fourier, a FFT. Cada saída da FFT equivale a um espectro discreto de um intervalo de tempo do som. Utilizando-se intervalos de tempo suficientemente curtos para não serem notados pela percepção auditiva, cada saída da FFT representará um espectro "instantâneo" do som. Cada espectro é manipulado por um operador timbral, com um dado parâmetro, e transformado novamente num trecho de som através da IFFT (FFT inversa) antes da próxima saída da FFT. Assim tem-se a manipulação do timbre do som. A parametrização on-line das operações timbrais pode ser feita por controladores externos e/ou informações do passado do som (espectros anteriores ao que está sendo manipulado num dado instante). Assim os espectros obtidos em cada FFT são armazenados numa pilha de vetores que, para um instante de tempo, pode ser vista como uma matriz. Desta matriz retira-se toda a informação sobre o som, ou na forma gráfica, representando a superfície sonora (superfície contínua que mostra a variação da envoltória do espectro no tempo), ou através da extração de parâmetros para as operações timbrais. Assim é possivel transformar e observar a transformação do som em tempo-real. Neste trabalho foi desenvolvido o estudo e projeto para um sistema de sintese timbral controlada pelo som analógico de entrada. Foram feitas simulações no MATLAB 4.0 para cada passo do processamento do som, tais como: o pré-processamento e a conversão AlD e D/A, a obtenção do espectro discreto pela FFT e o retorno ao domínio do tempo pela IFFT, o armazenamento dos espectro na forma de pilha de vetores, as operações timbrais e os resultados alcançados em termos gráficos e auditivos (no padrão u-Iaw). No final do trabalho é proposto um projeto para o sistema, utilizando o DSP 96002 (IEEE floatting-point, dual-port processor) da MOTOROLA
Abstract: Not informed.
Mestrado
Mestre em Engenharia Elétrica

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PERISSINATO, Aline Gravinez. "Formulações sólidas de lactase: estudos de estabilidade acelerada, liberação e sua quantificação por espectroscopia no infravermelho." Universidade Federal de Alfenas, 2016. https://bdtd.unifal-mg.edu.br:8443/handle/tede/767.

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A intolerância à lactose é caracterizada pela falta da enzima lactase (β-galactosidase) e atinge quase 50% da população. O tratamento se baseia em uma dieta restritiva de produtos lácteos o que pode acarretar em prejuízo nutricional e estar associada com a diminuição da densidade mineral óssea e fraturas. Nosso objetivo foi avaliar uma formulação de lactase gastro-resistente para garantir uma maior atividade no local de ação da enzima (lúmen do intestino delgado). Concomitantemente, também avaliamos a estabilidade e a atividade enzimática do produto comercial americano (comprimidos de Lactaid® 9000 U). E por fim, desenvolvemos um método analítico para quantificar o teor de lactase em formulações sólidas através da espectroscopia na região do infravermelho. Ao realizar o teste de estabilidade nota-se que a embalagem primária é fundamental na manutenção da atividade enzimática da lactase. Ao término do estudo de estabilidade, os comprimidos que estavam dentro da sua embalagem primária tiveram uma diminuição da sua atividade de aproximadamente 7,5%, enquanto os comprimidos que foram armazenados fora da sua embalagem original tiveram uma perda de aproximadamente 35%. Ao realizar o teste de dissolução também do produto comercial americano nota-se que a formulação existente não é capaz de proteger a enzima da ação degradante do ambiente gástrico do estômago, apresentando ao final do teste uma perda de 65% de atividade enzimática. Em comparação com a forma farmacêutica gastro-resistente, não houve perda de atividade durante a etapa ácida e ao final do ensaio de dissolução a atividade encontrada foi de 93%. Quanto ao método de quantificação por infravermelho, constatou-se que a o melhor modelo de calibração multivariada (PLS) apresenta 7 VL, RMSECV de 4,3 %, RMSEP de 1,2% e os dados obtidos com o MIR é muito similar com os dados obtidos pelo método USP de referência.
Lactose intolerance is characterized by the absence of the enzyme lactase (β-galactosidase) and affects almost 50% of the population. The treatment is based on a restrictive diet of dairy products which can result in nutritional loss and is associated with decreased bone mineral density and fractures. Our aim was to evaluate a lactase gastro formulation to ensure increased activity in the action site of the enzyme (lumen of the small intestine). Simultaneously, we also evaluated the stability and enzyme activity of the american commercial product (tablets of Lactaid® 9000 U). And lastly, we developed an analytical method for measuring the lactase content in solid formulations by spectroscopy in the infrared region. In carrying out the stability test to note that the primary packaging is critical in maintaining the enzymatic activity of lactase. At the end of the stability study, the tablets that were in the primary package had a decrease in their activity by approximately 7.5%, while the tablets were stored outside of its original container had a loss of approximately 35%. When carrying out dissolution test also the american commercial product it is noted that the existing formulation is not able to protect the enzyme from the degrading action of gastric environment of the stomach, with the end of the test a loss of 65% of enzyme activity. Compared with the gastroresistant pharmaceutical form there was no loss of activity during the acid step and the end of the dissolution test the activity was found 93%. As regards the measurement method by IR, it was found that the best multivariate calibration model (PLS) features 7 LV, RMSECV 4.3%, RMSEP of 1.2% and the data obtained with MIR is very similar to the data obtained by the USP reference method.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES

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Raele, Marcus Paulo. "Desenvolvimento de um sistema de tomografia por coerência óptica no domínio de Fourier sinsível á polarização e sua utilização na determinação das matrizes de Mueller." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-16112009-165948/.

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Este estudo abordou os aspectos teóricos e experimentais relacionados ao desenvolvimento de um sistema de tomografia por coerência óptica (OCT) no domínio de Fourier sensível à polarização (PS-FD-OCT) e a sua utilização na determinação da Matriz de Mueller (MM-OCT). O estudo iniciou-se com uma revisão bibliográfica que abordou desde os primeiros estudos relacionados à técnica até o estado da arte, bem como o formalismo matemático da interferometria de baixa coerência no domínio espectral e polarização da luz. Realizaram-se estudos baseados em simulação numérica sobre três tipos diferentes de algoritmos, responsáveis pela recuperação do sinal de espalhamento, sendo eles: a Transformada de Fourier Direta; Interpolação e Zero-Filling. Ao fim dessa etapa concluiu-se que o algoritmo Zero-Filling 2N apresentou melhores características quando comparado aos outros algoritmos. Na parte experimental, primeiramente, diferentes arranjos OCT foram montados e medidas realizadas para verificação aspectos relacionados à teoria. Consecutivamente, utilizando uma amostra polimérica, realizaram-se imagens de birrefringência, que permitiram a determinação da birrefringência da amostra quantitativamente. Finalmente, imagens em diferentes estados de polarização foram realizadas, através delas determinou-se as imagens referentes aos elementos das Matrizes de Mueller, que foram analisadas individualmente.
This study approached theoretical and experimental aspects related with the development of a polarization sensitive, Fourier domain, optical coherence tomography system (PS-FD-OCT) and its utilization on the Mueller Matrix determination. This work began with a bibliographic revision, which describes since the early studies to the actual state of the art of the technique. The mathematical formalism of Fourier domain low coherence interferometry and light polarization was performed as well. Studies based on numerical simulations, of three different algorithm types, responsible to recover the scattering profile, were done. The implemented algorithms were: Direct Fourier Transform, Interpolation and Zero-Filling. By the end of the simulation study, was possible to conclude that the algorithm Zero-Filling 2N presented better characteristics when compared with the others. In the experimental part, firstly different OCT setups were assembled and measurements were done in order to verify aspects related with the theory. Then, using a polymeric sample, birefringence images were performed, which allowed determining the sample birefringence quantitatively. Finally, images taken of different polarization states were collected, and through then images related with the Mueller Matrix elements were calculated, which were analyzed individually.

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Gazzoni, Fernando Estevam. "Medidor de pressão e dose sonora." Universidade Tecnológica Federal do Paraná, 2009. http://repositorio.utfpr.edu.br/jspui/handle/1/1334.

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CAPES; CNPq
O estudo dos sons e a influência que ele exerce nos seres humanos foi intensificado nas últimas décadas devido ao grande número de veículos e indústrias nos centros das grandes cidades. O equipamento usado para caracterizar o som e verificar se ele está dentro dos padrões técnicos é o medidor de intensidade sonora ou sonômetro. As normas permitem que sejam comercializados desde equipamentos que medem apenas o nível de pressão sonora até equipamentos que além do nível de pressão sonora mostram seu espectro em freqüência e pressão média a que um operador foi exposto durante a jornada de trabalho. No Brasil, a maioria dos sonômetros comercializados que não medem apenas a pressão sonora normalmente são importados. O presente trabalho visa criar um protótipo de sonômetro capaz de medir a pressão sonora, caracterizar o sinal medido na freqüência e calcular a dose a que um indivíduo é exposto. Foi desenvolvido um sonômetro do tipo 2 com curvas de resposta lenta, rápida e impulsiva, com análise espectral em freqüência usando filtros de banda de oitava e com curvas de ponderação A e C. Os testes do software desenvolvido e da resposta do circuito montado foram realizados usando a curva de ponderação C, que é quase linear e por isso melhor para verificar a resposta em freqüência do circuito eletrônico projetado. A captura das medidas com curvas de ponderação A. Nos testes de dose de ruído foi usada a curva de ponderação A. Para testes usando ondas periódicas os resultados obtidos com o sonômetro usando as curvas de resposta lenta, rápida e impulsiva apresentaram resultados iguais, conforme esperado pela norma IEC 651. O firmware apresentou boa resolução em freqüência nos testes e respondeu de forma eficiente à variação de amplitude e freqüência do sinal sonoro de entrada. Os testes de bancada foram realizados comparando o resultado do protótipo com um sonômetro comercial e a medida de alguns sinais sonoros apresentou diferença elevada entre seus valores mínimo e máximo. Esse erro deve-se ao ruído de fundo da sala de testes, do microfone utilizado e dos erros intrínsecos ao processo da Transformada Rápida de Fourier (FFT), tais como espalhamento espectral devido à descontinuidade do início e fim da janela de amostragem, número de amostras da janela. O uso do filtro de decimação intensificou os erros ao redor da freqüência de 250Hz. A dose de ruído calculada pelo sonômetro foi proporcional ao aumento da intensidade sonora da fonte, conforme registrado pelo dosímetro comercial, porém sempre registrando um valor maior que o esperado.
The study of sounds and the influence it exerts in humans has intensified in recent decades due to the large number of vehicles and industries in the centers of large cities. The equipment used to characterize the sound and compare if it is within the technical standards is the sound intensity meter or sound level meter. The standards allow marketed since equipment that only measure the sound pressure level to equipment that show pressure level spectrum in frequency and mean pressure to which an operator was exposed during the workday. In Brazil, most sound level meters marketed that measure the sound pressure, the others are usually imported. The present work aims to create a prototype of sound level meters capable of measuring the sound pressure, characterize the signal measured in the frequency and calculate the dose to which an individual is exposed. We developed a sonometer type 2 with slow, fast and impulsive response curves, with spectral analysis using frequency filters and octave band weighting curves A and C. The testing software developed and the response of the developed circuit were performed using the C weighting curve, which is almost linear and therefore best to check the frequency response of the electronic circuit designed. In tests of noise dose and sound pressure level was used weighting curve A. For tests using periodic waves the results obtained with the sound level meter using the response curves of slow, fast and impulsive showed similar results, as expected by IEC 651. The firmware had good resolution in frequency in testing and responded efficiently to fluctuations in the amplitude and frequency of the sound signal input. The bench tests were performed comparing the results of the prototype with a marketed sonometer and some measure of sounds presented high difference in their minimum and maximum values. This error is due to the background noise of the testing room, the microphone used and the errors inherent to the process of fast Fourier transform (FFT), such as spread spectrum due to the discontinuity at the beginning and end of the sampling window, number of samples of the window. The use of the decimation filter intensified errors around the frequency of 250Hz. The calculated noise dose meter reading was proportional to the increase in the intensity of the sound source, as recorded by the marketed dosimeter, but recording a value greater than expected.

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ROMANO, REBECA da S. G. "Estudo da irradiação do polipropileno para possibilitar o controle de sua degradação ambiental." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28012.

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O PP é descartado em grande quantidade no meio ambiente, tendo em vista seu consumo muito elevado derivado de suas excelentes propriedades químicas e físicas, boa processabilidade e baixo custo. As radiações ionizantes, não ionizantes (UV e infravermelho), bem como o oxigênio e os poluentes podem causar a degradação do polipropileno (PP). A exposição à radiação ionizante pode causar na molécula de PP cisão de cadeia principal, reticulação e peroxidação (na presença de ar) entre outras. Este estudo tem como objetivo, o desenvolvimento de um PP oxidegradável por meio do controle da degradação induzida por radiação ionizante. As amostras foram processadas por injeção e expostas ao envelhecimento natural durante 180 dias e ao envelhecimento acelerado em estufa á 100°C por 192 dias e depois caracterizadas por avaliação visual, ensaios mecânicos, FTIR, SEM, DSC, TGA e DRX. As amostras de PP Grão 20 kGy, após o envelhecimento natural, apresentaram maior oxidação com presença de fissuras superficiais mais intensamente do que o PP d2w®. A resistência a tração do PP irradiado foi superior ao PP d2w® e os resultados do alongamento na ruptura mostraram uma diminuição intensa se compararmos o PP irradiado e o PP d2w® com o PP. Após a exposição natural espécies os índices de vinila e carbonila aumentaram ligeiramente devido as reações Norrish. O grupo carbonila promove uma oxidação contínua, junto à superfície fazendo com que o polímero diminua sua massa molar. O efeito da degradação natural foi evidente na ordem PP Grão 20 kGy > PP Grão 12,5 kGy = PP d2w® > PP. Por conseguinte, este conceito pode ser utilizado para produzir um PP com propriedades oxi-degradáveis de uma forma controlável.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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SOUZA, CLECIA de M. "Utilização da radiação ionizante na reciclagem de pneus inservíveis de automóvel e sua destinação ambiental adequada." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10613.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Peloux, Marius. "Nouveaux composants optiques pixellises pour la correction visuelle : modélisation, optimisation et évaluation." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00799958.

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Ce manuscrit de thèse traite de l'étude de verres ophtalmiques microstructurés et plus particulièrement pixellisés, ces derniers pouvant présenter un intérêt particulier en optique active pour la correction de la presbytie. Une étude théorique est proposée, permettant d'analyser les performances optiques d'une lentille pixellisée en termes de transport d'image et d'identifier les paramètres qui ont un impact direct sur ces performances. Après validation expérimentale des résultats obtenus, nous constatons puis expliquons l'effet sur l'observation d'une scène de l'excentrement de l'œil par rapport à la fonction de phase du verre. Nous étudions l'effet du repliement de phase inhérent aux limites des technologies de fabrication, qui vient ajouter un chromatisme axial aux défauts visuels engendrés par la pixellisation. Nous nous intéressons ensuite aux applications possibles de la pixellisation en optique passive. Nous prouvons que pour une application visée, des lentilles binaires non pixellisées, dont nous optimisons la qualité optique, conduisent à de meilleurs résultats que les lentilles pixellisées. L'impact sur l'acuité visuelle des phénomènes diffractifs parasites induits par la pixellisation est évalué au moyen d'un banc de mesure utilisant la simulation de certaines images telles qu'elles seraient vues au travers de verres ophtalmiques pixellisés. Enfin, nous menons une étude de l'aspect esthétique d'un verre pixellisé vu par un observateur externe, à partir de modèles de calcul hybrides mêlant optique géométrique et optique de Fourier.

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Doneux, Thomas. "Caractérisation par électrochimie et spectroscopie infrarouge in situ d'une électrode d'or (111) modifiée par du 2-mercaptobenzimidazole." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210969.

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Résumé du travail

L’étude des modifications de surfaces, et plus particulièrement des matériaux d’électrodes est un domaine en plein essor. Les modifications d’électrodes par voie organique ont des applications potentielles dans des domaines aussi variés que l’inhibition de la corrosion, l’électronique moléculaire, l’optoélectronique ou encore les biosenseurs.

Dans ce travail, nous nous sommes intéressés à l’électrode d’Au (111) modifiée par du 2-mercaptobenzimidazole.

Dans un premier temps, l’adsorption du MBI sur électrode d’Au (111) sous contrôle du potentiel a été examinée par des mesures de capacité, de voltampérométrie cyclique, de chronocoulométrie et de spectroscopie SNIFTIR in situ.

Les mesures de capacité révèlent qu’en milieu neutre, la molécule de MBI s’adsorbe en un film compact à des potentiels supérieurs à -0,3 V (vs. ECS). En deçà de cette valeur, le film se dilue progressivement lorsque le potentiel est rendu plus négatif, jusqu’à une valeur de -0,9 V où les molécules de MBI sont totalement désorbées de la surface.

La morphologie des voltampérogrammes subit des variations significatives au cours du temps. Ces changements montrent que l’adsorption du MBI s’accompagne d’une levée de reconstruction de la surface, qui passe d’une structure initiale (√3 x 22) à une structure (1 x 1). Une estimation de la quantité de MBI adsorbée est obtenue par intégration des courbes de densité de courant.

La courbe de densité de charge interfaciale a été extraite des mesures de chronocoulométrie. Cette courbe de densité de charge fournit des informations quant à l’évolution de l’excès superficiel en fonction du potentiel.

La qualité des spectres infrarouges relevés in situ nous a permis d’effectuer des analyses qualitatives et quantitatives. Celles-ci montrent une bonne corrélation avec les résultats électrochimiques et apportent une signature moléculaire du film adsorbé et des espèces issues de sa désorption. Des calculs basés sur la Théorie de la Fonctionnelle de la Densité (DFT) ont permis une bonne interprétation des spectres infrarouges du MBI et de certains de ses dérivés. En outre, nous avons pu déterminer l’orientation des molécules à la surface, et montré que celle-ci varie peu avec le potentiel.

Dans un second temps, nous nous sommes focalisés sur les propriétés de la monocouche auto-assemblée de MBI sur électrode d’Au (111), déterminées par voltampérométrie cyclique et spectroscopie infrarouge in situ. La monocouche est stable lorsque le potentiel est maintenu dans un domaine d’environ 800 mV. La monocouche auto-assemblée de MBI subit un processus de désorption réductive, influencé par le temps d’immersion de l’électrode dans la solution de surfactant ainsi que par le pH du milieu. Deux mécanismes de désorption réductive sont proposés, l’un valable en milieu neutre et basique, l’autre en milieu acide. Les résultats des mesures de spectroscopie infrarouge in situ apportent une preuve moléculaire de la validité des mécanismes proposés sur base des résultats électrochimiques.

Un rapide examen des potentialités de cette monocouche a été réalisé à l’aide de réactions sondes.

/

Abstract

Studies on surface modifications, and particularly of electrode material, are a growing field of interest. Organic modifications of electrode surfaces have potential applications in domains such as corrosion inhibition, molecular electronics, optoelectronics or biosensors.

In the present work, we focussed on the modification of Au(111) electrodes by 2-mercaptobenzimidazole (MBI).

In the first part, the adsorption, under potential control, of the MBI molecule onto the Au(111) electrode was studied by means of capacitance measurements, cyclic voltammetry, chronocoulometry and in-situ SNIFTIR spectroscopy.

Capacitance measurements indicate that in neutral solution, the MBI molecule is adsorbed as a compact film at potentials higher than -0.3 V (vs. SCE). Below this value, the film becomes progressively less dense when the potential is made more negative, until a value of -0.9 V where MBI molecules are totally desorbed from the surface.

The shape of the voltammograms evolves significantly with time. These changes show that a lift of the surface reconstruction occurs concomitantly to the adsorption of MBI. The initial (√3 x 22) reconstructed structure is lifted to the (1 x 1) unreconstructed one. The amount of adsorbed MBI is estimated by integration of the current density curves.

The interfacial charge density curve was obtained by chronocoulometry measurements. This curve provides useful data regarding the evolution of the surface concentration with the potential.

The quality of the infrared spectra obtained in situ allowed us to perform quantitative as well as qualitative analyses of the results. These analyses show a good correlation with the electrochemical results and provide molecular information on the adsorbed layer and on the species formed during the desorption process. Density Functional Theory (DFT) calculations were helpful in the interpretation of the infrared spectra of MBI and some of its derivatives. Additionally, we were able to determine the orientation of the molecules on the surface, and demonstrated that this orientation is slightly affected by the potential.

In the second part of the work, we investigated the properties of the self-assembled monolayer of MBI on Au(111) electrode by cyclic voltammetry and in situ infrared spectroscopy. The monolayer is stable within an 800 mV potential range. The self-assembled monolayer undergoes a reductive desorption process, which is affected by the pH of the medium and by the immersion time of the electrode into the surfactant solution. Two mechanisms were proposed for the reductive desorption, one being valid in neutral and basic media, the other in acidic conditions. The in situ infrared spectroscopic results provide molecular evidences supporting the mechanisms proposed on an electrochemical basis.

An exploratory examination of the potentialities of the monolayer is made by means of electrochemical probe reactions.

Doctorat en sciences, Spécialisation chimie
info:eu-repo/semantics/nonPublished

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Buiar, Celso Luiz. "Formulação analítica para a solução da equação de transferência radiativa sem simetria azimutal com inclinação do feixe incidente / por Celso Luiz Buiar ; [orientador, Luís Mauro Moura]." reponame:Biblioteca Digital de Teses e Dissertações da PUC_PR, 2005. http://www.biblioteca.pucpr.br/tede/tde_busca/arquivo.php?codArquivo=242.

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Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, Curitiba, 2005
Inclui bibliografia
Esta dissertação versa sobre uma metodologia empregada para a solução da Equação de Transferência de Calor por Radiação (ETR) de materiais classificados como semitransparentes difusores (MST), em uma geometria unidimensional sem simetria azimutal em funçã

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FERREIRA, MAIARA S. "Imobilização da quitosana da carapaça de siri Charybdis hellerii em filmes poliméricos a partir de sua obtenção com o uso da radiação ionizante." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27125.

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A quitosana é um polisacarídeo obtido pela desacetilação das moléculas de quitina, principal constituinte de alguns fungos e do exoesqueleto de crustáceos e insetos. Os grupos amino presentes na quitosana conferem-lhe importantes propriedades biológicas, como a biodegradação, biocompatibilidade, atividade/efeitos imunológicos e atividade antibacteriana. A desacetilação da quitina é um processo cuja conversão é agressiva, já que exige o ataque da quitina em solução de álcalis em alta concentração e à quente, com duração de 6 a 8 horas. Neste trabalho, carapaças de siri da espécie Charybdis hellerii foi fragmentada e pré-tratada para a obtenção da quitosana e cada etapa, desde o pré-tratamento do material in natura à sua conversão em quitosana, foi investigada detalhadamente. Observou-se que dose e taxa de dose não influenciaram no pré-tratamento ou na etapa de desacetilação da quitina; na dose de 20 kGy (gama ou feixe de elétrons), o processo de conversão teve duração de 60 minutos. A quitosana obtida teve baixa massa molar e grau de desacetilação comparável á quitosana padrão (SA), dependendo das condições de irradiação. Além disso, apresentou inibição da atividade bacteriana tanto livre como imobilizada em substratos poliméricos de polipropileno e de polietileno processados também por radiação ionizante.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Rifaai, Yasser. "Rhéologie des matrices hybrides composées de ciment et d’ajouts cimentaires activés." Thesis, CY Cergy Paris Université, 2020. http://www.theses.fr/2020CYUN1069.

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Face aux préoccupations environnementales liées à la production du ciment Portland, la recherche d’alternatives pour une construction plus durable s’avère une nécessité. En effet, la production du ciment est responsable de l’augmentation du potentiel de réchauffement global (PRG), ce qui remet en question sa grande utilisation de point de vue environnemental. Dans cette perspective, ce projet de doctorat s’inscrit dans l’optique de la réduction de l’impact environnemental des matériaux de construction, notamment les bétons fluides à rhéologie adaptée. Les géopolymères se présentent comme l’une des alternatives intéressantes pouvant réduire l’impact environnemental de la construction. Cependant, l’introduction de ces matériaux dans le secteur de construction confronte des difficultés de compréhension de leurs mécanismes de prise et de durcissement.Ainsi, l’objectif principal de cette thèse est d’étudier l’impact de l’activateur alcalin sur le comportement rhéologique et les mécanismes de prise des géopolymères à base de cendres volantes et de poudre de verre activées ainsi que des matrices hybrides composées de ciment et de géopolymères. Plus spécifiquement, cette étude vise à améliorer les performances rhéologiques et les caractéristiques viscoélastiques de ces matrices afin de les incorporer dans la matrice des bétons fluides, notamment le béton autoplaçant. Le couplage des mesures rhéologiques avec la spectroscopie infrarouge à transformée de Fourier et la microstructure permet de comprendre les différents mécanismes régissant le comportement à l’état frais des matrices étudiées. Les résultats obtenus ont permis d’identifier les concentrations optimales de l’activateur alcalin pour obtenir les meilleures performances rhéologiques, tout en prenant en considération les performances à l’état durci requises. La méthodologie utilisée dans cette étude a permis également de lier les performances rhéologiques au processus de géopolymérisation afin d’établir une meilleure compréhension de l’état frais de ces matériaux. Finalement, l’incorporation des pâtes optimisées dans la matrice d’un béton autoplaçant a été également évaluée. Le béton autoplaçant à base de matrice hybride a montré des performances rhéologiques et mécaniques prometteuses, ainsi qu’un potentiel de réchauffement global inférieur à celui du béton autoplaçant conventionnel. Ces résultats montrent que l’utilisation de ce nouveau type de béton autoplaçant propose une solution intéressante de point de vue environnemental, tout en maintenant les performances rhéologiques et mécaniques requises
With the increase of the environmental concerns related to the production of Portland cement, the search for alternatives to achieve sustainable and rational construction is becoming a necessity. Indeed, the production of cement is responsible for the increase in global warming potential (GWP), which questions its widespread use from an environmental point of view. In this perspective, this study aims at reducing the environmental impact of building materials, in particular self-consolidating concrete (SCC). Geopolymers are one of the interesting alternatives that can reduce the environmental impact of construction. However, the incorporation of these materials in the construction markets faces difficulties as long as the understanding of their setting and hardening mechanisms is still a hot topic.The main objective of this thesis is to evaluate the impact of alkaline activator on the setting mechanisms and rheological behaviour of geopolymers based on fly ash, alkali-activated glass powders, and hybrid matrices composed of cement and geopolymers. This study aims to assess the rheological properties and viscoelastic characteristics of these matrices and evaluate the feasibility of incorporating them to design SCC. Coupling the rheological properties with other measures, including Fourier-transform infrared spectroscopy and microstructure, makes it possible to define different mechanisms governing the fresh state of the investigated matrices. The obtained results allowed to identify the optimal concentrations of the alkaline activator to achieve the required rheological properties and mechanical performance. In addition, the methodology used in this study allowed to correlate the rheological properties to the geopolymerization process. This allowed better understanding of the fresh state of these materials. Finally, the incorporation of the optimized pastes into the matrix of SCC was also evaluated. Self-consolidating concrete based on hybrid matrix has shown promising rheological and mechanical performances, as well as a lower global warming potential than conventional SCC proportioned with cementitious materials. These results proved that the use of hybrid SCC offers an interesting solution from an environmental point of view, while achieving the required rheological and mechanical performances

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Terschlüsen, Joachim A. "Constructing and Commissioning HELIOS – A High Harmonic Generation Source for Pump-Probe Measurements with sub 50 fs Temporal Resolution : The Development of Experimental Equipment for Extreme Ultraviolet Spectroscopy." Doctoral thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-281298.

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This thesis presents HELIOS, an in-house laboratory for time-resolved pump-probe spectroscopy with extreme-ultraviolet (XUV) probe radiation. A wide span of pump wavelengths can be generated using commercial laser equipment while XUV probe radiation is generated via a high harmonic generation process in a noble gas delivering probe photons with energies between 20 eV and 72 eV. The XUV beam path features a time-preserving monochromator and was constructed and built in-house. HELIOS features an overall time resolution of about 50 fs when using 800 nm pump and 41 eV probe photons. An energy resolution of 110 meV at 41 eV photon energy can be achieved. HELIOS features two beamlines. One µ-focus beamline with an XUV focal size of about 20 µm can be used with experiments that require such a small XUV focal size as well as with different end stations. The other beamline features a semi-permanently mounted end station for angle-resolved photoelectron spectroscopy under ultra-high vacuum conditions. Experiments demonstrating the usability of HELIOS and the two beamlines are presented. A pump-probe measurement on graphene demonstrates the capability of determining a large part of the k-space in only one measurement due to the use of an ARTOF angle-resolved time-of-flight electron spectrometer. A non-angle-resolved pump-probe measurement on the conducting polymer PCPDTBT demonstrates the high signal-to-noise ratio achievable at this beamline in non-angle-resolved photoelectron-spectroscopy pump-probe measurements. The usability of the µ-focus beamline is demonstrated with time-resolved measurements on magnetic samples employing an in-house-designed spectrometer. These experiments allow the retrieval of element-specific information on the magnetization within a sample employing the transversal magneto-optical Kerr effect (T-MOKE). Additionally, a Fourier transform spectrometer for the XUV is presented, the concept was tested at a synchrotron and it was used to determine the longitudinal coherence of the XUV radiation at HELIOS.

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Paiva, S?mara de Cavalcante. "Prote??o em sistemas el?tricos com gera??o distribu?da utilizando a transformada wavelet." Universidade Federal do Rio Grande do Norte, 2015. http://repositorio.ufrn.br/handle/123456789/20243.

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Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)
Um sistema el?trico de pot?ncia t?pico ? caracterizado pela centraliza??o da gera- ??o de energia. Entretanto, com a reestrutura??o do sistema el?trico, esta topologia vem modificando-se com a utiliza??o de geradores ao longo do sist ema de distribui??o (gera- ??o distribu?da) que proporciona diversos benef?cios por l ocalizar-se pr?ximo aos centros de consumo. Com isso, a inser??o de geradores distribu?dos, especialmente provenientes de fontes renov?veis, no sistema brasileiro tende a se torna r a cada ano mais comum. En- tretanto, esta nova configura??o do sistema traz novos desafi os concernentes ao controle, opera??o e prote??o. Um dos principais problemas da gera??o distribu?da nos sistemas de prote??o ? a forma??o de ilhamentos, que pode resultar em ris cos de seguran?a ?s pessoas e a rede de energia el?trica. Dentre as diversas t?cnicas de p rote??o de ilhamentos, as t?cnicas passivas destacam-se devido ao custo de implement a??o e simplicidade, sendo necess?rias apenas medi??es de tens?o e corrente para detec ??o de problemas no sistema. Prop?e-se neste trabalho um sistema de prote??o baseado na t ransformada wavelet com as fun??es de sobrecorrente, sub/sobretens?es e informa?? es dos transit?rios de falta para r?pida detec??o e identifica??o de situa??es de falta no sist ema. O esquema de prote??o proposto foi avaliado por meio de estudos de simula??o e expe rimental, apresentando de- sempenho similar aos m?todos de sobrecorrente e sub/sobret ens?o convencionais, por?m, com o adicional da detec??o do instante exato das faltas.
A typical electrical power system is characterized by centr alization of power gene- ration. However, with the restructuring of the electric sys tem, this topology is changing with the insertion of generators in parallel with the distri bution system (distributed gene- ration) that provides several benefits to be located near to e nergy consumers. Therefore, the integration of distributed generators, especially fro m renewable sources in the Brazi- lian system has been common every year. However, this new sys tem topology may result in new challenges in the field of the power system control, ope ration, and protection. One of the main problems related to the distributed generati on is the islanding formation, witch can result in safety risk to the people and to the power g rid. Among the several islanding protection techniques, passive techniques have low implementation cost and simplicity, requiring only voltage and current measuremen ts to detect system problems. This paper proposes a protection system based on the wavelet transform with overcur- rent and under/overvoltage functions as well as infomation of fault-induced transients in order to provide a fast detection and identification of fault s in the system. The propo- sed protection scheme was evaluated through simulation and experimental studies, with performance similar to the overcurrent and under/overvolt age conventional methods, but with the additional detection of the exact moment of the fault.

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Kleinhans, Henrik. "Evaluation of the Carbonization of Thermo-Stabilized Lignin Fibers into Carbon Fibers." Thesis, Linköpings universitet, Kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120519.

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Thermo-stabilized lignin fibers from pH-fractionated softwood kraft lignin were carbonized to various temperatures during thermomechanical analysis (TMA) under static and increasing load and different rates of heating. The aim was to optimize the carbonization process to obtain suitable carbon fiber material with good mechanical strength potential (high tensile strength and high E-modulus). The carbon fibers were therefore mainly evaluated of mechanical strength in Dia-Stron uniaxial tensile testing. In addition, chemical composition, in terms of functional groups, and elemental (atomic) composition was studied in Fourier transform infrared spectroscopy (FTIR) and in energy-dispersive X-ray spectroscopy (EDS), respectively. The structure of carbon fibers was imaged in scanning electron microscope (SEM) and light microscopy. Thermogravimetrical analysis was performed on thermo-stabilized lignin fibers to evaluate the loss of mass and to calculate the stress-changes and diameter-changes that occur during carbonization. The TMA-analysis of the deformation showed, for thermo-stabilized lignin fibers, a characteristic behavior of contraction during carbonization. Carbonization temperatures above 1000°C seemed most efficient in terms of E-modulus and tensile strength whereas rate of heating did not matter considerably. The E-modulus for the fibers was improved significantly by slowly increasing the load during the carbonization. The tensile strength remained however unchanged. The FTIR-analysis indicated that many functional groups, mainly oxygen containing, dissociate from the lignin polymers during carbonization. The EDS supported this by showing that the oxygen content decreased. Accordingly, the relative carbon content increased passively to around 90% at 1000°C. Aromatic structures in the carbon fibers are thought to contribute to the mechanical strength and are likely formed during the carbonization. However, the FTIR result showed no evident signs that aromatic structures had been formed, possible due to some difficulties with the KBr-method. In the SEM and light microscopy imaging one could observe that porous formations on the surface of the fibers increased as the temperature increased in the carbonization. These formations may have affected the mechanical strength of the carbon fibers, mainly tensile strength. The carbonization process was optimized in the sense that any heating rate can be used. No restriction in production speed exists. The carbonization should be run to at least 1000°C to achieve maximum mechanical strength, both in E-modulus and tensile strength. To improve the E-modulus further, a slowly increasing load can be applied to the lignin fibers during carbonization. The earlier the force is applied, to counteract the lignin fiber contraction that occurs (namely around 300°C), the better. However, in terms of mechanical performance, the lignin carbon fibers are still far from practical use in the industry.

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Málková, Eliška. "Monitorování pohybu více objektů užitím křížové korelace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400456.

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Tato práce popisuje metodu analýzy translačního pohybu užitím křížové korelace. Ukazujeme, jakým způsobem se chová funkce křížové korelace obrazů s navzájem posunutými objekty, a jak nám to umožňuje nacházet jejich vektory posunu. Pro následnou implementaci je nalezena efektivní metoda pro hledání pouze požadovaného počtu lokálních maxim funkce.

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43

Moriana, Torró Rosana. "Desarrollo y caracterización de biocomposites enfibrados procedentes de recursos renovables. Estudio de su degradación en tierra." Doctoral thesis, Universitat Politècnica de València, 2010. http://hdl.handle.net/10251/8958.

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El propósito de la presente Tesis Doctoral es estudiar y predecir las características y la biodegradabilidad de diferentes biocomposites desarrollados a partir de materiales biodegradables procedentes de fuentes renovables. Para ello, se emplean dos termoplásticos de base almidón como matrices poliméricas (Mater-Bi KE03B1 y Mater-Bi NF01U ), que se refuerzan con distintas fibras naturales (algodón, cáñamo, kenaf, lino y yute) con el fin de mejorar sus propiedades mientras están en servicio, al tiempo que se mantiene su biodegradabilidad. Las fibras naturales, las matrices poliméricas y los biocomposites reforzados se caracterizan con el objetivo de estudiar de la influencia de cada fibra natural en las propiedades de la matriz polimérica. Para ello se emplea una metodología basada en el Análisis Espectroscópico (FTIR-ATR), Mecánico (Ensayos de Tensión), Morfológico (SEM) y Térmico (DMTA, TGA, DSC). Así mismo se establecen correlaciones entre la composición química de las fibras naturales y las propiedades de los biocomposites reforzados. La degradabilidad de las matrices poliméricas y de los biocomposites se evalúa mediante enasayos de degradación en tierra y de absorción en agua. La hidrólisis de las matrices poliméricas y de los biocomposites se estudia como étapa previa a su biodegradación en tierra. Ambos procesos, la degradación en tierra y la absorción de agua se monitorizan mediante cambios en las propiedades térmicas. En particular, los parámetros térmicos de control escogidos son: las temperaturas de inicio y máxima velocidad de termodegradación como marcador de la estabilidad térmica; y las energías de activación de cada proceso de descomposición, puesto que este parámetro permite discernir los cambios en los entornos moleculares que facilitan o dificultan el proceso de termodegradación. Estos estudios de degradación, se complementan con análisis morfológicos y espectroscópicos. Finalmente, se confirma que el Mater-Bi NF y el Mater-Bi KE aumentan sus aplicaciones cuando se refuerzan con fibras naturales al mismo tiempo que mantienen su capacidad para degradarse en el momento en el que finaliza su vida útil. En el diseño del biocomposite, la selección de una u otra fibra natural como material de refuerzo dependerá de las propiedades finales requeridas.
Moriana Torró, R. (2010). Desarrollo y caracterización de biocomposites enfibrados procedentes de recursos renovables. Estudio de su degradación en tierra [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8958
Palancia

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Hammadi, Shumoos T. H. "Novel medical imaging technologies for processing epithelium and endothelium layers in corneal confocal images. Developing automated segmentation and quantification algorithms for processing sub-basal epithelium nerves and endothelial cells for early diagnosis of diabetic neuropathy in corneal confocal microscope images." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/16924.

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Diabetic Peripheral Neuropathy (DPN) is one of the most common types of diabetes that can affect the cornea. An accurate analysis of the corneal epithelium nerve structures and the corneal endothelial cell can assist early diagnosis of this disease and other corneal diseases, which can lead to visual impairment and then to blindness. In this thesis, fully-automated segmentation and quantification algorithms for processing and analysing sub-basal epithelium nerves and endothelial cells are proposed for early diagnosis of diabetic neuropathy in Corneal Confocal Microscopy (CCM) images. Firstly, a fully automatic nerve segmentation system for corneal confocal microscope images is proposed. The performance of the proposed system is evaluated against manually traced images with an execution time of the prototype is 13 seconds. Secondly, an automatic corneal nerve registration system is proposed. The main aim of this system is to produce a new informative corneal image that contains structural and functional information. Thirdly, an automated real-time system, termed the Corneal Endothelium Analysis System (CEAS) is developed and applied for the segmentation of endothelial cells in images of human cornea obtained by In Vivo CCM. The performance of the proposed CEAS system was tested against manually traced images with an execution time of only 6 seconds per image. Finally, the results obtained from all the proposed approaches have been evaluated and validated by an expert advisory board from two institutes, they are the Division of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar and the Manchester Royal Eye Hospital, Centre for Endocrinology and Diabetes, UK.

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45

Langerome, Benjamin. "Spectroscopie infrarouge de matériaux supraconducteurs dans des conditions extrêmes de haute pression ou basse température." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS343.

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La supraconductivité est intensément étudiée en physique de la matière condensée pour ses éventuelles applications. En effet, ce phénomène est caractérisé macroscopiquement par des propriétés remarquables, mais pour le moment, son exploitation est limitée par la nécessité de refroidir ces matériaux à des températures cryogéniques. Après la découverte de H₃S, dont la température de transition est de 200 K, un renouveau d’intérêt est apparu pour les matériaux supraconducteurs conventionnels. Pour ce composé, le couplage entre électrons et phonons est à l’origine de l’appariement électronique, une condition nécessaire à la supraconductivité. L’énergie associée à ce couplage se trouve généralement dans la gamme des infrarouges lointains, voire des THz, faisant de la spectroscopie infrarouge un outil idéal pour étudier ce mécanisme. Cette thèse présente les études de deux matériaux supraconducteurs dans des conditions expérimentales extrêmes de pression ou de température, permise grâce à la forte brillance du rayonnement synchrotron. Pour la phase supraconductrice H₃S à des pressions supérieures à 150 GPa, l’environnement en cellule à enclumes de diamant exclut la plupart des techniques pour déterminer la nature du mécanisme mais les études optiques restent adaptées. Les résultats spectroscopiques présentés ici démontrent un fort couplage entre électrons et phonons, qui explique l’origine d’une si haute température de transition. Des mesures complémentaires visant à caractériser NaCl sous pression sont également décrites car ce matériau est couramment utilisé comme transmetteur de pression dans les cellules `a haute pression, notamment pour le supraconducteur H₃S. La deuxième étude rapporte des résultats spectroscopiques dans le THz sur des couches nanométriques de Nb, dont les températures de transition supraconductrice sont de 4,5 K et 6,8 K. Ces mesures confirment que la nature conventionnelle du mécanisme subsiste au sein de ces films minces quasi-bidimensionnels. Pour ce travail, un ensemble instrumental permettant la mesure spectroscopique de matériaux jusqu’à des températures de 200 mK a été entièrement développé autour d’un cryostat à démagnétisation adiabatique
Superconductivity is highly studied in condensed matter physics for its potential applications. Indeed, this phenomenon is macroscopically characterized by remarkable properties, but generally occurs in materials at cryogenic temperature thus limitating their exploitation. Recently, renewed interest has appeared for conventional superconducting materials with the discovery of H₃S, whose transition temperature is at 200 K. For this compound, the coupling between electrons and phonons is at the origin of the electronic pairing, a necessary condition for superconductivity. The associated energy for this coupling belongs to the far infrared range, even THz, making infrared spectroscopy an ideal tool to study the mechanism. This thesis presents the studies of two superconducting materials in extreme experimental conditions of pressure and temperature, allowed by the high brilliance of synchrotron radiation. For the superconducting phase H₃S under pressures superior to 150 GPa, the environment of diamond anvil cell excludes most of the techniques to determine the nature of the mechanism but the optical studies remain adapted. The spectroscopic results presented here demonstrate a strong coupling between electrons and phonons, which explains the origin of such a high transition temperature. Complementary measurements aiming at characterizing NaCl under pressure is also described because this material is often used as a pressure transmitting medium in high pressure cells, in particular for the superconducting H₃S. The second study reports spectroscopic results in the THz on nanometric layers of Nb, whose superconducting transition temperatures are 4,5 K and 6,8 K. These measurements confirm that the conventional nature of the mechanism subsists within these quasi-bidimensional thin films. For this work, an instrumental ensemble allowing the spectroscopic measurements of materials down to 200 mK has been entirely developed based on an adiabatic demagnetization cryostat

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46

Cadiou, François. "Étude de l'impact de la microstructure sur les propriétés effectives électriques des batteries lithium-ion." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI108.

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Cette étude porte sur la compréhension du lien existant entre l’architecture microstructurelle et les propriétés effectives de conductivité dans les électrodes des batteries Li-ion. Les batteries Li-ion sont très intéressantes pour des domaines tels que le transport électrique. En effet, elles présentent une grande densité d’énergie et de puissance ce qui en fait de bons substituts pour les moteurs thermiques. Cependant, même si elles sont maintenant assez largement utilisées dans beaucoup de domaines, il y a toujours besoin d’en optimiser les performances. Ceci passe par une meilleure compréhension de l’impact de la microstructure sur les propriétés effectives pour réduire l’écart entre théorie et pratique. L’attention est portée ici sur les électrodes positives des batteries lithium-ion. Les caractéristiques tridimensionnelles telles que la percolation des phases, leur tortuosité ou encore leurs dimensions caractéristiques ont un fort impact sur les propriétés à l'échelle macroscopique. Leur étude nécessite l’utilisation de techniques d’imagerie 3D comme la tomographie aux rayons X et la tomographie sériée par faisceau d’ions focalisés et MEB (FIB/SEM) pour obtenir des données quantitatives et en interpréter les propriétés de transport de charge. Ces volumes sont alors traités (segmentation et analyses morphologiques) et utilisés comme base pour des simulations numériques. La méthode FFT (Fast Fourrier Transform) avec opérateur de Green « discret » est choisie. Ces simulations permettent, soit de remonter aux propriétés de conduction électrique des phases, à partir de la mesure de la conductivité de l’électrode, par méthode inverse, soit de prédire la conductivité effective de l’électrode, en utilisant des propriétés mesurées expérimentalement sur les phases prises séparément. Les microstructures 3D numériques peuvent également être altérées afin de prédire l’impact, sur ses propriétés effectives, de changements de composition dans la formulation de l’électrode. De nouveaux outils consacrés à la meilleure compréhension de la relation entre microstructure, propriétés effectives et performance des batteries lithium-ion sont développés
Li-ion batteries are interesting for applications such as electric vehicles. They have indeed a high energy and power density, which makes them good substitutes for internal combustion engines. However, even if they are now quite widely used in many fields, there is still a need to optimize their performance. This requires a better understanding of the impact of the electrodes microstructure on their effective properties to narrow the gap between ideal and practical performance. Three-dimensional characteristics such as the carbon additive percolation or the tortuosity of the porosity have a strong impact on the electrode charge transport properties and power performance. The use of 3D imaging techniques such as X-ray tomography and serial focused ion beam and SEM tomography (FIB/SEM) is very powerful to quantify the electrode microstructures and interpret their charge transport properties. Furthermore, by processing the reconstructed volumes, one can use them as a basis for numerical simulations. We have chosen the FFT (Fast Fourrier Transform) method with "discrete" Green operator for numerical computations. These simulations can either be used to back calculate the phase (active material or conducting additive/binder) conduction properties from macroscopic electrical measurements by inverse method, or to predict the electrode effective conductivity from the phase conductivities. The 3D numerical microstructures obtained can also be modified in order to predict the influence of compositional changes in the electrode formulation on its properties. This study sets new tools to understand better the relationships between microstructure, effective electrical properties and the performance of Li-ion battery composite electrodes

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Mohammed, Saad Abdul Basset. "Caracterisation par spectroscopie ft-ir de l'adsorption et de la reactivite de composes sulfures sur alumine : effet de l'ajout de sodium." Caen, 1986. http://www.theses.fr/1986CAEN2030.

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La spectroscopie ft-ir est appliquee a l'etude des proprietes superficielles d'echantillons d'alumine, a la determination de la nature des especes donnees par l'adsorption de composes soufres et a la recherche des intermediaires de reaction pouvant expliquer le mecanisme du procede de claus. L'addition de na**(+), diminue l'acidite de lewis de l'alumine. L'acidite de broensted induite par la presence des especes sulfate est certainement cause de la desactivation de l'alumine dans la reaction de conversion oxydante de h::(2)s. Cas, aussi, de l'adsorption sur de la silice sodee

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48

Clemente, Sandrina Eloísa Guerra. "Impacto do processo de lavação na qualidade das rolhas naturais." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14911.

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Mestrado em Biotecnologia Industrial e Ambiental
O presente trabalho desenvolvido na Amorim & Irmãos, S.A., teve como objetivo principal o estudo do impacto das alterações do processo de lava-ção na qualidade das rolhas naturais. A lavação destina-se a assegurar a limpeza, desinfeção e branqueamento das rolhas de cortiça, contribuindo para uma melhoria do seu aspeto visual e ausência de microrganismos. Foram recolhidas duas amostras, uma antes, L1, e outra L2,depois, de alterações introduzidas ao processo, como ajustes aos programas da lava-ção, que foram analisadas em diferentes etapas: na sua forma natural, após a lavação, e como produto final. De forma a avaliar o efeito das alterações ao processo sobre a qualidade das rolhas foram aplicados os métodos de controlo realizados na Amorim & Irmãos, S.A. e, para melhor caracterizar os produtos e o seu comporta-mento nas rolhas de cortiça, métodos de controlo complementar, como a análise da brancura, Espectroscopia de Infravermelho com Transformada de Fourrier e Refletância Total Atenuada (FTIR-ATR) e Microscopia Eletró-nica de Varrimento (SEM). Pode concluir-se que o impacto das alterações feitas ao processo foi posi-tivo, traduzindo-se numa melhoria da performance das rolhas pertencentes à amostra L2, quando comparada com L1, refletida em alguns dos resulta-dos dos métodos de controlo realizados, como o aspeto visual e uniformi-dade da superfície das rolhas ao longo do processo de marcação. As aná-lises de FTIR-ATR e SEM revelaram-se inconclusivas na comparação en-tre L1 e L2, apesar de demonstrarem que a estrutura da cortiça é preser-vada após a lavação e o tratamento de superfície.
The present work developed in Amorim & Irmãos, S.A., aims the study of the impact of industrial washing process modifications in the quality of natu-ral cork stoppers. Washing is intended to ensure cork stoppers cleaning, disinfection and bleaching, contributing to an improvement of their visual aspect and an absence of microorganisms. Two samples were collected, one before, L1, and L2, after process modifications, and were analyzed at different stages: natural, after washing and as a final product. Assays methods accomplished in Amorim & Irmãos, S.A, were applied to better characterize the products and their behavior in cork stoppers. Com-plementary analysis methods were also performed, namely whiteness analysis, Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and Scanning Electron Microscopy (SEM). It can be concluded that the process modifications had a positive impact, translated into a performance improvement of L2 sample compared to L1. That improvement was proved with some of analysis results, such as visual analysis and the stoppers superficial uniformity during branding process. FTIR-ATR and SEM analyses were inconclusive when samples L1 and L2 were compared. However, they demonstrated that the cork structure was preserved after washing and surface treatment, for both samples.

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Lamotte, Jean. "Etude par spectroscopie infrarouge des proprietes superficielles de la thorine et des especes adsorbees resultant de l'interaction co + h : :(2)." Caen, 1987. http://www.theses.fr/1987CAEN2047.

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Abrahams, Dhielnawaaz. "Charge Transfer and Capacitive Properties of Polyaniline/ Polyamide Thin Films." University of the Western Cape, 2018. http://hdl.handle.net/11394/6361.

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Magister Scientiae - MSc (Chemistry)
Blending polymers together offers researchers the ability to create novel materials that have a combination of desired properties of the individual polymers for a variety of functions as well as improving specific properties. The behaviour of the resulting blended polymer or blend is determined by the interactions between the two polymers. The resultant synergy from blending an intrinsically conducting polymer like polyaniline (PANI), is that it possesses the electrical, electronic, magnetic and optical properties of a metal while retaining the poor mechanical properties, solubility and processibility commonly associated with a conventional polymer. Aromatic polyamic acid has outstanding thermal, mechanical, electrical, and solvent resistance properties that can overcome the poor mechanical properties and instability of the conventional conducting polymers, such as polyaniline.

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