Dissertations / Theses on the topic 'Sum Fourier'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Sum Fourier.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Müllner, Clemens. "Exponential sum estimates and Fourier analytic methods for digitally based dynamical systems." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0042/document.
Full textThe 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
Литвин, О. М., and 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.
Full textRavindran, 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.
Full textMcGuire, 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/.
Full textPublished 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.
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.
Full textPh. D.
Li, Jialun. "Harmonic analysis of stationary measures." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0311/document.
Full textLet 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
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.
Full textDel, Gatto Davide. "Analisi di Fourier sui Gruppi." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18784/.
Full textNoorizadeh, Sahand. "SLM-based Fourier Differential Interference Contrast Microscopy." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/2011.
Full textPotts, 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.
Full textMarquezino, 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.
Full textPeloux, Marius. "Nouveaux composants optiques pixellisés pour la correction visuelle : modélisation, optimisation et évaluation." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112202/document.
Full textThis 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
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/.
Full textMORIN, PHILIPPE. "Couplage chromatographie en phase dioxyde de carbone supercritique-spectrometrie infrarouge a transformee de fourier." Paris 6, 1988. http://www.theses.fr/1988PA066684.
Full textROBB, 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.
Full textNicacio, 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.
Full textDissertação (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
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.
Full textFord, 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.
Full textPetit, Jérôme. "Contrôle dimensionnel sub-micrométrique utilisant un appareil goniométrique bidimensionnel rapide." Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10211.
Full textThis 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
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.
Full textM.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
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.
Full textMade available in DSpace on 2014-10-09T13:58:18Z (GMT). No. of bitstreams: 0
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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/.
Full textVidal, 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/.
Full textThe 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.
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.
Full textPhase 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
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.
Full textHebert, 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.
Full textBARONI, 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.
Full textMade available in DSpace on 2014-01-15T12:38:00Z (GMT). No. of bitstreams: 1 dissertacao_mestrado_ien_2008_03.pdf: 2115567 bytes, checksum: 8434c1181cfea6af8d33936cea7cdb1e (MD5) Previous issue date: 2008
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.
Novo, Junior José Eduardo Fornari 1966. "Transformações sonoras atraves de operações timbrais." [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261415.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica
Made available in DSpace on 2018-07-22T03:45:49Z (GMT). No. of bitstreams: 1 NovoJunior_JoseEduardoFornari_M.pdf: 6190852 bytes, checksum: d35d2cada94640837d01f78009fcc27f (MD5) Previous issue date: 1995
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
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.
Full textLactose 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
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/.
Full textThis 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.
Gazzoni, Fernando Estevam. "Medidor de pressão e dose sonora." Universidade Tecnológica Federal do Paraná, 2009. http://repositorio.utfpr.edu.br/jspui/handle/1/1334.
Full textO 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.
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.
Full textMade available in DSpace on 2017-11-16T17:00:32Z (GMT). No. of bitstreams: 0
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
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.
Full textMade available in DSpace on 2014-10-09T14:02:09Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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.
Full textDoneux, 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.
Full textL’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
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.
Full textInclui 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
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.
Full textMade available in DSpace on 2017-03-10T13:21:18Z (GMT). No. of bitstreams: 1 22063.pdf: 2189055 bytes, checksum: e74fe1aad4947b67467c366506647b8d (MD5)
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
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.
Full textWith 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
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.
Full textPaiva, 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.
Full textApproved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-04-19T23:21:12Z (GMT) No. of bitstreams: 1 SamaraDeCavalcantePaiva_DISSERT.pdf: 3765795 bytes, checksum: eed2c79e7ce6b6439acadf41bfab260e (MD5)
Made available in DSpace on 2016-04-19T23:21:12Z (GMT). No. of bitstreams: 1 SamaraDeCavalcantePaiva_DISSERT.pdf: 3765795 bytes, checksum: eed2c79e7ce6b6439acadf41bfab260e (MD5) Previous issue date: 2015-06-22
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.
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.
Full textMálková, 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.
Full textMoriana, 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.
Full textMoriana 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
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.
Full textLangerome, 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.
Full textSuperconductivity 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
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.
Full textLi-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
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.
Full textClemente, 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.
Full textO 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.
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.
Full textAbrahams, Dhielnawaaz. "Charge Transfer and Capacitive Properties of Polyaniline/ Polyamide Thin Films." University of the Western Cape, 2018. http://hdl.handle.net/11394/6361.
Full textBlending 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.