This dissertation is focused on the research of the applicability of the thermographic method in the diagnosis of concrete bridges in the Czech Republic. The theoretical part characterizes selected defects of concrete structures and the principle of their detection. The practical part describes the measurements made in the laboratory on the test specimen and the field on the concrete bridge. Most attention is paid to infrared thermography, ground-penetrating radar and ultrasonic pulse-echo method. Based on the results of the dissertation, recommendations for the use of the thermographic test method in practice were developed.

L'objectif de ce projet de recherche est la mise au point et l'utilisation de charges inorganiques barrière aux rayonnements infrarouge pour la préparation de matériaux d'enduction à base de plastisols PVC. Dans un premier temps, cette étude a été consacrée à la caractérisation rhéologique, morphologique et optique de la matrice PVC et à l'élaboration de nouvelles formulations, en incorporant dans le plastisol des charges commerciales de natures chimiques différentes (nacre, billes de verre, alumine, oxyde de Zinc, TiO2 …). Ensuite, des mesures radiatives sur des films de plastisols chargés à différents taux massiques ont été réalisées dans le but de sélectionner les charges présentant les meilleures performances optiques. Enfin, les formulations optimales ont été enduites sur un textile polyester et la stabilité des revêtements soumis à des rayonnements UV a été suivie par plusieurs techniques analytiques. Diverses caractérisations mécaniques, esthétiques et morphologiques sont venues compléter cette étude. Dans un second temps, un modèle de transfert radiatif permettant de simuler la propagation du rayonnement dans les systèmes de protection développés a été testé / This project aims to develop new filled PVC plastisol composite offering enhanced optical properties. Different types of inorganic fillers were tested and added to the PVC matrix. Rheological, morphological and optical characterization of the PVC matrix and development of new formulations by incorporation of different fillers (nacre, glass beads, alumina, zinc oxide, TiO2 ...) were the subject of the first phase of the project. Then, radiative measurements on plastisol films loaded at different mass ratios were performed in order to select the fillers having the best optical performance. The second phase was dedicated to the validation and the testing of the optimal formulations coated on polyester textile substrate. Different analytic technics were used in order to rank the UV stabilization as a function of the tested formulations. In addition, mechanical, aesthetic and morphological characterizations were used to complete this study. Finally, radiative transfer model was developed to simulate the radiative behavior of the different formulations

Um Amplificador Paramétrico Óptico (optical parametric amplifier - OPA) é uma fonte de luz coerente, de alta qualidade e sintonizável, baseada em processos ópticos não-lineares de segunda ordem. Alguns modelos possuem largura de banda estreita e um amplo intervalo de sintonia, podendo alcançar regiões que vão desde o ultravioleta até o infravermelho médio. A nossa motivação para construir este amplificador paramétrico óptico é sua utilização em experimentos de espectroscopia vibracional de superfícies através do processo óptico não-linear de segunda ordem, geração de soma de frequências (sum-frequency generation - SFG), que é uma técnica que exige fontes sintonizáveis no infravermelho médio e com altas intensidades de pico e largura de banda estreita. O objetivo desse trabalho foi projetar, montar e testar um amplificador paramétrico óptico capaz de produzir pulsos sintonizáveis de alta energia no infravermelho médio (λ ~ 2,5 a 10 μm) a partir de um laser de bombeio que fornece pulsos de 25 ps, com alta energia em λ = 1064 nm. Para obter-se uma geração de infravermelho bastante eficiente, foi proposto um projeto inovador para amplificadores paramétricos de picossegundos, utilizando-se a geração de supercontínuo de luz branca como feixe sinal do estágio de amplificação paramétrica. O pulso de bombeio (λ = 1064 nm) é dividido em duas partes: a primeira, de menor energia, é utilizada para gerar um pulso de alta largura espectral no infravermelho próximo (supercontínuo de luz branca de picossegundos). Uma fração espectral desse pulso é selecionada através de um monocromador e utilizada como semente do estágio de amplificação paramétrica. O cristal amplificador paramétrico (sulfeto de prata e gálio, AgGaS2) é então bombeado pelo restante do pulso de bombeio e simultaneamente amplifica a semente sintonizável no infravermelho próximo e gera um novo pulso de frequência complementar no infravermelho médio. Foram testados vários meios para geração de supercontínuo, mas os melhores resultados foram obtidos em uma cubeta de 10 cm de comprimento com uma mistura de água e água deuterada (3 % em volume de H2O em D2O) e em uma fibra fotônica não-linear com 2 m de comprimento. Usando o supercontínuo como feixe semente, observou-se amplificação paramétrica no caso do feixe gerado na fibra fotônica com um ganho de 260 vezes, mas não com o feixe gerado na mistura de água/água deuterada, presumivelmente pela maior instabilidade desse supercontínuo. / An Optical Parametric Amplifier (OPA) is a tunable light source of high quality, coherent radiation, based on second-order nonlinear optical processes. Some models have a narrow spectral bandwidth and a tuning range from the ultraviolet to the mid-infrared. The motivation for building this optical parametric amplifier is its use in vibrational spectroscopy of surfaces by a second-order nonlinear optical process, sum-frequency generation (SFG), which is a technique that requires tunable sources in the mid-infrared with narrow bandwidth and high peak intensities. The purpose of this work is to design, implement and test an OPA to generate tunable high energy pulses tuneable in the mid-infrared (λ ~ 2.5 to 10 μm) from a pumping laser that provides 25 ps pulses with high energy at λ = 1064 nm. For an efficient mid-infrared generation, we propose an innovative design for picosecond parametric amplifiers, using the near infrared portion of a white-light supercontinuum pulse as the seed beam for the parametric amplifier. The pump pulse (λ = 1064 nm) is divided into two parts: the first one, with lower energy, generates a high spectral width pulse in the near infrared (white-light supercontinuum picosecond pulse). A spectral fraction of this pulse is selected through a monochromator and is used as seed for the parametric amplification stage. The second part of the laser beam pumps the parametric amplifier crystal (silver gallium sulfide, AgGaS2) which simultaneously amplifies the tunable seed beam in the near infrared and generates a new pulse with complementary frequency in the mid-infrared. Several media were tested for supercontinuum generation, but the best results were obtained with a 10 cm long cuvette with a mixture of water and deuterated water (3 % volume of H2O in D2O) and with a 2 m long nonlinear photonic crystal fiber. Using the supercontinuum as a seed beam, we have obtained parametric amplification of the seed generated by the photonic fiber with a gain of 260 times, but not of the beam generated by the water mixture, presumably because of its significantly higher instability.

Processos de fragmentação são muito utilizados para identificar estruturas em espectrometria de massas. O estudo da dissociação de íons em fase gasosa induzida por radiação infravermelha adiciona dados energéticos aos processos de fragmentação desses íons. O mecanismo de dissociação induzida por radiação infravermelha envolve a absorção seqüencial de fótons, aumentando progressivamente a energia interna do íon até que o limite de dissociação seja atingido. No presente trabalho, a radiação de corpo negro emitida por um fio de tungstênio aquecido é utilizada para promover a dissociação de íons em fase gasosa. A reação é observada em um espectrômetro de massas por transformada de Fourier. Os íons moleculares de o-metilacetofenona, m-metilacetofenona, p-metilacetofenona e o-cloroacetofenona foram estudados com a técnica. A dependência das constantes de velocidade de dissociação com a temperatura de radiação foi explorada, fornecendo valores de energia de ativação de Arrhenius. Os íons estudados apresentaram resultados semelhantes com aqueles obtidos com o íon molecular de acetofenona, com exceção do íon gerado por o-metilacetofenona. Esse íon apresenta valores de constantes de velocidades bem menores e uma energia de ativação bem acima do observado com os outros íons. Tal comportamento levantou a hipótese de isomerização do íon molecular para uma estrutura enólica mais estável. O íon foi então investigado por cálculos teóricos e por reações específicas íon-molécula. Os resultados indicam que a isomerização é possível, o que também explica a lentidão da reação de dissociação observada. / Fragmentation processes are explored in mass spectrometry to identify structures of ions and neutral molecules. The study of ion dissociation reaction in the gas phase induced by infrared absorption also provides energetic data related to the fragmentation processes. The mechanism of the dissociation by infrared radiation involves sequential photon absorption that progressively raises the internal energy of the ion population until the dissociation threshold. In the present work, the blackbody radiation emitted by a heated tungsten wire is used to promote ion dissociation in gas phase. The reaction is observed in a Fourier transform mass spectrometer. The molecular ions of o-methylacetophenone, m-methylacetophenone, p-methylacetophenone and o-chloroacetophenone were studied with this technique. The dependency of the dissociation rates with the radiation temperature was explored, providing Arrhenius activation energies values. The ions cited above and the molecular ion of acetophenone displayed similar behavior, with the exception of the ion produced by o-methylacetophenone. This ion has dissociation rates much smaller than the others and higher activation energy. This behavior raised the idea of isomerization of the molecular ion to the more stable enolic form. The ion was then investigated with theoretical calculation and with specific reaction with neutral molecules. The results show that the isomerization is possible and this explains the observed slowness of the dissociation reaction.

Processos de fragmentação são ferramentas fundamentais no estudo de íons por espectrometria de massas, pois permitem a obtenção de informação sobre a estrutura e termoquímica destes íons . Desenvolvemos uma técnica de dissociação de íons baseada na ativação destes através da absorção multifotônica sequencial de radiação infravermelha de um filamento incandescente. Nesta técnica, íons aprisionados na cela de um espectrômetro de massas por transformada de Fourier são submetidos a radiação do filamento por intervalos de tempo relativamente longos (da ordem de segundos), e passam por um processo de multíplos eventos de absorção e emissão de radiação, até a energia interna dos íons atingir um nível suficiente para a fragmentação. A partir deste modelo para o processo foram implementados métodos computacionais que permitem a simulação da dissociação. A realização destas simulações exige o conhecimento do espectro vibracional do íon, que normalmente tem que ser obtido por algum método teórico de cálculo, como foi feito neste trabalho paro o caso de alguns dos íons estudados. O método de dissociação unimolecular induzida por absorção de radiação infravermelha foi aplicado na determinação das energias de ativação e de dissociação dos íons moleculares de acetofenona, p-cimeno e cumeno. Este método também mostrou-se capaz de diferenciar diferentes estruturas isomericas, e foi com esta finalidade aplicado no estudo da isomerização ceto-enol do íon molecular de acetofenona. Demonstrou-se também a capacidade do método dissociar os íons moleculares de n-butilbenzeno e brometo de alila. / Fragmentation processes are fundamental tools for the mass spectrometric study of ions because they provide information on structure and termochemistry of these ions. We have developed a dissociation technique that is based on the multiphoton activation of trapped ions by infrared radiation emitted by an incandescent filament. In this technique, ions trapped in the cell of a Fourier Transform mass spectrometer are exposed to the filament radiation for long time periods (seconds), and a process of multiple absorption and emition events occurs, until the internal energy of the ions is high enough for fragmentation. Computational methods have been implemented from this model allowing for simulation of the dissociation process. For this simulation the ion vibrational spectra, that normally must be obtained from theoretical calculations, is also required, as has been done in this work for some of the studied ions. The method of unimolecular dissociation induced by infrared radiation was applied to the determination of activation and dissociation energies of the molecular ions of acetophenone, p-cymene and cumene. This method also proved to be capable in the differentiation of isomeric structures, and was so applied in the study for the keto-enol isomerization of the acetophenone molecular ion. It was also shown that the method can dissociate the molecular ions of n-butylbenzene an allyl bromide.

Μετά την πρώτη ενεργειακή κρίση την δεκαετία του ’70 κατά την οποία τα περιορισμένα αποθέματα ενέργειας προκάλεσαν την πρώτη σημαντική αύξηση στην τιμή της ενέργειας, η χρήση ενέργειας στα θερμοκήπια έχει γίνει κύριο ερευνητικό ζήτημα. Η ανάγκη για μείωση του ενεργειακού κόστους είναι σημαντική, γιατί η ενέργεια αποτελεί σημαντικό κλάσμα του συνολικού κόστους παραγωγής. Στις Μεσογειακές χώρες έχει υπολογιστεί ότι η χρήση ενέργειας για έλεγχο των συνθηκών περιβάλλοντος και ειδικότερα για τη θέρμανση, είναι 20% - 30% του συνολικού κόστους παραγωγής, ποσοστό το οποίο στις βορειότερες χώρες αυξάνεται. Ταυτόχρονα, με το έντονο ενδιαφέρον για το παγκόσμιο φαινόμενο του θερμοκηπίου και τις κλιματικές αλλαγές, η χρήση των συμβατικών καυσίμων είναι και πάλι στην πολιτική ατζέντα. Έτσι και η βιομηχανία θερμοκηπίων είναι αντιμέτωπη με οικονομική, πολιτική και κοινωνική πίεση για μείωση της χρήσης ενέργειας και βελτίωση της ενεργειακής απόδοσης των θερμοκηπίων μέσω τεχνολογικών καινοτομιών. Η κατανάλωση ενέργειας για τη θέρμανση του θερμοκηπίου αποτελεί ένα πολύ σοβαρό πρόβλημα διότι οι απώλειες του θερμοκηπίου σε θερμότητα λόγω των λεπτών τοιχωμάτων του και της κατασκευής του, είναι πολύ μεγάλες, 6-12 φορές μεγαλύτερες από εκείνες ενός συνήθους κτίσματος ίσου όγκου. Η θερμότητα παρέχεται στο θερμοκήπιο κυρίως μέσω συμβατικών συστημάτων θέρμανσης (συστήματα σωληνώσεων θερμού νερού, συστήματα θερμού αέρα) και σε περιορισμένη έκταση με χρήση ανανεώσιμων πηγών ενέργειας (ηλιακή, γεωθερμία, βιομάζα). Για να επιτευχθεί με αυτές τις μεθόδους η απαραίτητη θερμοκρασία στο επίπεδο των φυτών, το εσωτερικό του θερμοκηπίου πρέπει να θερμανθεί στην ίδια ή υψηλότερη θερμοκρασία από την επιθυμητή θερμοκρασία των φυτών με αποτέλεσμα την δημιουργία ισοθερμοκρασιακού κλίματος σε ολόκληρο το θερμοκήπιο (όλον κλίμα). Το αποτέλεσμα αυτής της πρακτικής σε όλες τις μελέτες που διεξάγονται είναι ότι, τα θερμοκήπια καταναλώνουν απαράδεκτα υψηλά ποσά ενέργειας σε σχέση με την ενέργεια που απορροφάται από τα φυτά, για να καλύπτουν τις αυξημένες ενεργειακές απώλειες που λόγω κατασκευής παρουσιάζουν. Στην παρούσα διατριβή αναπτύσσεται μια ολοκληρωμένη πρόταση για την δημιουργία ενός "ψυχρού θερμοκηπίου" στο οποίο τα φυτά θα λαμβάνουν απευθείας την ενέργεια που χρειάζονται προκειμένου να φτάσουν και να διατηρήσουν την επιθυμητή για την ανάπτυξή τους θερμοκρασία χωρίς να υπάρχει ανάγκη για αύξηση της θερμοκρασίας του αέρα του θερμοκηπίου. Για τον σκοπό αυτό χρησιμοποιείται σύστημα θέρμανσης με μικρού μήκους υπέρυθρη ακτινοβολία (NIR). Σε αυτά τα συστήματα η θερμότητα μεταδίδεται απευθείας από την πηγή στον δέκτη, στην προκειμένη περίπτωση στα φυτά και το έδαφος και το αποτέλεσμα είναι η δημιουργία ισοθερμοκρασιακού κλίματος μόνο στην περιοχή του φυτικού θόλου (τοπικό κλίμα). Ειδικότερα η παρούσα εργασία αντιμετωπίζει τη θερμική συμπεριφορά του θερμοκηπίου λαμβάνοντας υπόψη όλα τα ουσιαστικά θερμικά φαινόμενα που συμβαίνουν κατά την διάρκεια θέρμανσης (με συμβατικό και με σύστημα θέρμανσης με ακτινοβολία) και παρουσία καλλιέργειας. Γι αυτό τον λόγο δίνεται ιδιαίτερη βαρύτητα στην ανάπτυξη ενός μαθηματικού μοντέλου που προσομοιάζει επαρκώς τις κύριες διαδικασίες μεταφοράς θερμότητας μέσα στο θερμοκήπιο, το οποίο περιλαμβάνει ένα σύνολο λειτουργικών συνθηκών, και στο οποίο καθορίζονται με σχετική ακρίβεια οι παράγοντες που επηρεάζουν την θερμική συμπεριφορά του θερμοκηπίου. Το μοντέλο προσομοίωσης δίνει την δυνατότητα αξιόπιστης περιγραφής του περιβάλλοντος του θερμοκηπίου, και σαφούς εκτίμησης των ενεργειακών αναγκών του και με τις δυο τεχνικές θέρμανσης. Ετσι προσδιορίζεται το εξοικονομούμενο ενεργειακό όφελος που προκύπτει με τη χρήση συστήματος θέρμανσης με ακτινοβολία. Ο έλεγχος της ποιότητας του μοντέλου προσομοίωσης και η περαιτέρω βελτίωσή του γίνεται με σύγκριση των θεωρητικών αποτελεσμάτων με πειραματικά δεδομένα, η συλλογή και επεξεργασία των οποίων αποτελεί τον πυρήνα της έρευνας. Τα πειραματικά δεδομένα προέρχονται από πειράματα που διεξήχθησαν σε δύο πειραματικά θερμοκήπια συζευγμένα με αυτόματο μετεωρολογικό σταθμό, στα οποία εφαρμόζεται συμβατικό σύστημα θέρμανσης και θέρμανση με υπέρυθρη ακτινοβολία αντίστοιχα. Αυτό δίνει την δυνατότητα πιστοποίησης των δυνατοτήτων της θέρμανσης με ακτινοβολία και ποσοτικοποίησης του ενεργειακού οφέλους που επιτυγχάνεται. Συμπερασματικά, η συστηματική θεωρητική και πειραματική μελέτη ενός "ψυχρού" θερμοκηπίου με χρήση μικρού μήκους υπέρυθρης ακτινοβολίας (NIR) και ενός "θερμού θερμοκηπίου" με χρήση συμβατικού συστήματος θέρμανσης αναδεικνύουν το κύριο πλεονέκτημα της υπέρυθρης ακτινοβολίας, δηλαδή η θερμότητα να μεταδίδεται απευθείας από το σύστημα ακτινοβολίας στα φυτά και το έδαφος χωρίς να παρεμβάλεται ο αέρας του εσωτερικού περιβάλλοντος του θερμοκηπίου. Αυτό οδηγεί σε ομοιομορφία θέρμανσης του φυτικού θόλου και ταυτόχρονα σε σημαντική εξοικονόμηση ενέργειας της τάξεως του 40-50%. / After the first energy crisis in the seventies during which limited energy supplies led to an important increase in energy prices, greenhouse energy consumption has again become a major research issue. The energy cost reduction need is significant, since energy forms a substantial fraction of the total production costs. In Mediterranean countries it has been estimated that energy consumption for environment conditions control and more specifically for heating, consists 20% - 30% of total production cost, a percentage that is higher in northern countries. Moreover, due to the recent pronounced interest in the global greenhouse effect and climatic change, the use of fossil fuels is once again in the political agenda. Therefore the greenhouse industry is confronted with economical, political and social pressure to reduce energy usage and improve the greenhouse energy efficiency via technological innovations. Energy consumption for greenhouse heating represents a serious concern because greenhouse heat losses due to thin covers and construction specifics are 6-12 times higher than those of a common building of equal volume. Traditionally, thermal energy is transmitted to the greenhouse mainly through conventional heating systems (either by hot water circulation through a piping system or by air heaters) and, in a limited scale, through renewable energy sources (solar, geothermal, biomass). In order for the plants to reach required temperature through these methods, the greenhouse interior has to be heated to the same or even to a slightly higher temperature than the value targeted for the plants (entire climate). This practice results in extremely increased heat losses compared to the energy absorbed by plants, because of the increased energy losses due to construction specifications. The present thesis formulates a complete proposal for the creation of a "cold greenhouse" where plants will directly receive the needed energy in order to reach and preserve the desirable growth temperature without having to increase the internal greenhouse air temperature. The near infrared radiation (NIR) is used for this purpose. In the radiation system, heating is transmitted straight from the source to the receiver, in this particular case plants and soil. The result is an isothermal climate formation in the plant canopy (local climate). Specifically this study investigates the greenhouse thermal performance taking into account all the essential thermal phenomena that take place during heating (conventional and IR heating) and cultivation. For this reason, emphasis is given to the development of a mathematical model that simulates the main heating transfer procedures inside the greenhouse, takes into account a sum of operational conditions and determines all factors influencing the greenhouse thermal performance with relevant accuracy. The simulation model allows a credible description of greenhouse environment as well as a clear estimation of its energy needs with both heating systems. Thus the resulting energy saving by IR heating usage is determined. Quality control of the simulation model and its forward improvement is done by comparing the theoretical results with experimental data. Collecting and processing these data forms the research kernel. The experimental data correspond to experiments that took place in two experimental greenhouse connected with automatic meteorological station where conventional and IR heating have been used respectively. This method makes possible the identification of IR heating potential and quantification of energy saving. Concluding, the systematic theoretical and experimental study of a "cold" greenhouse using near IR heating, and of a "warm" greenhouse using conventional heating, proves the main advantage of IR heating that is that, the heat is directly transferred from the radiation system to the plants and the soil without interference of the internal greenhouse air. This leads to uniform heating of the plant canopy and at the same time to a significant energy saving of 40-50%.

Processos de fragmentação são muito utilizados para identificar estruturas em espectrometria de massas. O estudo da dissociação de íons em fase gasosa induzida por radiação infravermelha adiciona dados energéticos aos processos de fragmentação desses íons. O mecanismo de dissociação induzida por radiação infravermelha envolve a absorção seqüencial de fótons, aumentando progressivamente a energia interna do íon até que o limite de dissociação seja atingido. No presente trabalho, a radiação de corpo negro emitida por um fio de tungstênio aquecido é utilizada para promover a dissociação de íons em fase gasosa. A reação é observada em um espectrômetro de massas por transformada de Fourier. Os íons moleculares de o-metilacetofenona, m-metilacetofenona, p-metilacetofenona e o-cloroacetofenona foram estudados com a técnica. A dependência das constantes de velocidade de dissociação com a temperatura de radiação foi explorada, fornecendo valores de energia de ativação de Arrhenius. Os íons estudados apresentaram resultados semelhantes com aqueles obtidos com o íon molecular de acetofenona, com exceção do íon gerado por o-metilacetofenona. Esse íon apresenta valores de constantes de velocidades bem menores e uma energia de ativação bem acima do observado com os outros íons. Tal comportamento levantou a hipótese de isomerização do íon molecular para uma estrutura enólica mais estável. O íon foi então investigado por cálculos teóricos e por reações específicas íon-molécula. Os resultados indicam que a isomerização é possível, o que também explica a lentidão da reação de dissociação observada. / Fragmentation processes are explored in mass spectrometry to identify structures of ions and neutral molecules. The study of ion dissociation reaction in the gas phase induced by infrared absorption also provides energetic data related to the fragmentation processes. The mechanism of the dissociation by infrared radiation involves sequential photon absorption that progressively raises the internal energy of the ion population until the dissociation threshold. In the present work, the blackbody radiation emitted by a heated tungsten wire is used to promote ion dissociation in gas phase. The reaction is observed in a Fourier transform mass spectrometer. The molecular ions of o-methylacetophenone, m-methylacetophenone, p-methylacetophenone and o-chloroacetophenone were studied with this technique. The dependency of the dissociation rates with the radiation temperature was explored, providing Arrhenius activation energies values. The ions cited above and the molecular ion of acetophenone displayed similar behavior, with the exception of the ion produced by o-methylacetophenone. This ion has dissociation rates much smaller than the others and higher activation energy. This behavior raised the idea of isomerization of the molecular ion to the more stable enolic form. The ion was then investigated with theoretical calculation and with specific reaction with neutral molecules. The results show that the isomerization is possible and this explains the observed slowness of the dissociation reaction.

Les systèmes d'éclairage automobiles sont conçus pour éclairer la route de manière optimale. Une dégradation des optiques et des matériaux plastiques peut altérer la qualité du faisceau lumineux. En phase de conception, les simulations thermiques visent à minimiser les coûts engendrés par les tests expérimentaux réalisés sur des maquettes. Avec le développement de nouvelles optiques, la méthode numérique des ordonnées discrètes, utilisée pour le calcul des transferts radiatifs, souffre d'un manque de précision en raison d'une discrétisation spatiale limitée pour les réflexions spéculaires. Une augmentation de la discrétisation pourrait mener à des temps de calculs importants. Pour palier à ce problème, la méthode de Monte Carlo a été choisie afin d'évaluer les densités de flux aux parois dans le cas des surfaces opaques, ou un terme source radiatif dans le cas des matériaux semi-Transparents. Notre algorithme est implémenté dans l'environnement de développement EDStar. Cet environnement inclut la bibliothèque de synthèses d'images PBRT permettant de reproduire les trajets optiques dans une géométrie 3D complexe. L'étude porte sur des produits d'éclairage composés de lampes, ainsi le développement d'un modèle numérique fiable requiert des paramètres pertinents en entrée de modèle. Les travaux ont donc été scindés en trois axes d'études. Le premier inclut une phase de caractérisation des propriétés thermiques d'une lampe à incandescence (25W). Différentes méthodes de mesures ont été étudiées pour déterminer la température du filament, moteur des transferts thermiques, et la température de l'enveloppe. Le second axe consiste à développer un modèle des transferts radiatifs dans le système d'éclairage. L'objectif est de localiser les zones de concentration du rayonnement et estimer leur étendue. Enfin, le troisième axe vise à coupler le calcul radiatif à des simulations thermiques dans l'outil de CFD Fluent. La CFD (Computational Fluid Dynamics) est ici nécessaire pour résoudre les problèmes convectifs couplés aux autres transferts thermiques dans un produit industriel. / Automotive lighting systems are designed to illuminate the road optimally. Degradation of optical properties or plastics materials may altering the quality of lighting. In the design stage, thermal simulations are intended to minimize the costs of experimental tests performed on prototypes. With the apparition of new headlights optics, the Discrete Ordinates method (DO) is not suitable in certain cases due to a lack of accuracy when dealing with specular reflections and refractions. A raise of the spatial discretization could lead to significant time computation. To overcome this problem, we chose the Monte Carlo method in order to estimate flux densities to the walls in the case of opaque surfaces, or to estimate a radiative source term in the case of semi-Transparent media. Our algorithm is implemented in EDStar coding environment. This environment includes the PBRT synthesis images library allowing the use of raytracing techniques with our algorithm, thus reproducing optical paths of rays in a complex 3D geometry. The development of a reliable numerical model requires relevant parameters in input. This need led us to split the work into three main parts. The first axis includes a characterization phase of thermal properties of an incandescent lamp (25W) in order to model its radiative emission. Different measurements methods have been investigated to determine the temperature of the filament, which is the origine of heat transfers, and the temperature of the glass envelope. The second axis consists in obtaining a precise distribution of flux density distributions in order to locate hot spots and assess their extent. Finally, the third part of study is to couple the radiative calculation to CFD (Computational Fluid Dynamics) simulations. CFD is here necessary to solve problems with convective phenomena coupled with other heat transfers in an industrial product.

Um Amplificador Paramétrico Óptico (optical parametric amplifier - OPA) é uma fonte de luz coerente, de alta qualidade e sintonizável, baseada em processos ópticos não-lineares de segunda ordem. Alguns modelos possuem largura de banda estreita e um amplo intervalo de sintonia, podendo alcançar regiões que vão desde o ultravioleta até o infravermelho médio. A nossa motivação para construir este amplificador paramétrico óptico é sua utilização em experimentos de espectroscopia vibracional de superfícies através do processo óptico não-linear de segunda ordem, geração de soma de frequências (sum-frequency generation - SFG), que é uma técnica que exige fontes sintonizáveis no infravermelho médio e com altas intensidades de pico e largura de banda estreita. O objetivo desse trabalho foi projetar, montar e testar um amplificador paramétrico óptico capaz de produzir pulsos sintonizáveis de alta energia no infravermelho médio (λ ~ 2,5 a 10 μm) a partir de um laser de bombeio que fornece pulsos de 25 ps, com alta energia em λ = 1064 nm. Para obter-se uma geração de infravermelho bastante eficiente, foi proposto um projeto inovador para amplificadores paramétricos de picossegundos, utilizando-se a geração de supercontínuo de luz branca como feixe sinal do estágio de amplificação paramétrica. O pulso de bombeio (λ = 1064 nm) é dividido em duas partes: a primeira, de menor energia, é utilizada para gerar um pulso de alta largura espectral no infravermelho próximo (supercontínuo de luz branca de picossegundos). Uma fração espectral desse pulso é selecionada através de um monocromador e utilizada como semente do estágio de amplificação paramétrica. O cristal amplificador paramétrico (sulfeto de prata e gálio, AgGaS2) é então bombeado pelo restante do pulso de bombeio e simultaneamente amplifica a semente sintonizável no infravermelho próximo e gera um novo pulso de frequência complementar no infravermelho médio. Foram testados vários meios para geração de supercontínuo, mas os melhores resultados foram obtidos em uma cubeta de 10 cm de comprimento com uma mistura de água e água deuterada (3 % em volume de H2O em D2O) e em uma fibra fotônica não-linear com 2 m de comprimento. Usando o supercontínuo como feixe semente, observou-se amplificação paramétrica no caso do feixe gerado na fibra fotônica com um ganho de 260 vezes, mas não com o feixe gerado na mistura de água/água deuterada, presumivelmente pela maior instabilidade desse supercontínuo. / An Optical Parametric Amplifier (OPA) is a tunable light source of high quality, coherent radiation, based on second-order nonlinear optical processes. Some models have a narrow spectral bandwidth and a tuning range from the ultraviolet to the mid-infrared. The motivation for building this optical parametric amplifier is its use in vibrational spectroscopy of surfaces by a second-order nonlinear optical process, sum-frequency generation (SFG), which is a technique that requires tunable sources in the mid-infrared with narrow bandwidth and high peak intensities. The purpose of this work is to design, implement and test an OPA to generate tunable high energy pulses tuneable in the mid-infrared (λ ~ 2.5 to 10 μm) from a pumping laser that provides 25 ps pulses with high energy at λ = 1064 nm. For an efficient mid-infrared generation, we propose an innovative design for picosecond parametric amplifiers, using the near infrared portion of a white-light supercontinuum pulse as the seed beam for the parametric amplifier. The pump pulse (λ = 1064 nm) is divided into two parts: the first one, with lower energy, generates a high spectral width pulse in the near infrared (white-light supercontinuum picosecond pulse). A spectral fraction of this pulse is selected through a monochromator and is used as seed for the parametric amplification stage. The second part of the laser beam pumps the parametric amplifier crystal (silver gallium sulfide, AgGaS2) which simultaneously amplifies the tunable seed beam in the near infrared and generates a new pulse with complementary frequency in the mid-infrared. Several media were tested for supercontinuum generation, but the best results were obtained with a 10 cm long cuvette with a mixture of water and deuterated water (3 % volume of H2O in D2O) and with a 2 m long nonlinear photonic crystal fiber. Using the supercontinuum as a seed beam, we have obtained parametric amplification of the seed generated by the photonic fiber with a gain of 260 times, but not of the beam generated by the water mixture, presumably because of its significantly higher instability.

Processos de fragmentação são ferramentas fundamentais no estudo de íons por espectrometria de massas, pois permitem a obtenção de informação sobre a estrutura e termoquímica destes íons . Desenvolvemos uma técnica de dissociação de íons baseada na ativação destes através da absorção multifotônica sequencial de radiação infravermelha de um filamento incandescente. Nesta técnica, íons aprisionados na cela de um espectrômetro de massas por transformada de Fourier são submetidos a radiação do filamento por intervalos de tempo relativamente longos (da ordem de segundos), e passam por um processo de multíplos eventos de absorção e emissão de radiação, até a energia interna dos íons atingir um nível suficiente para a fragmentação. A partir deste modelo para o processo foram implementados métodos computacionais que permitem a simulação da dissociação. A realização destas simulações exige o conhecimento do espectro vibracional do íon, que normalmente tem que ser obtido por algum método teórico de cálculo, como foi feito neste trabalho paro o caso de alguns dos íons estudados. O método de dissociação unimolecular induzida por absorção de radiação infravermelha foi aplicado na determinação das energias de ativação e de dissociação dos íons moleculares de acetofenona, p-cimeno e cumeno. Este método também mostrou-se capaz de diferenciar diferentes estruturas isomericas, e foi com esta finalidade aplicado no estudo da isomerização ceto-enol do íon molecular de acetofenona. Demonstrou-se também a capacidade do método dissociar os íons moleculares de n-butilbenzeno e brometo de alila. / Fragmentation processes are fundamental tools for the mass spectrometric study of ions because they provide information on structure and termochemistry of these ions. We have developed a dissociation technique that is based on the multiphoton activation of trapped ions by infrared radiation emitted by an incandescent filament. In this technique, ions trapped in the cell of a Fourier Transform mass spectrometer are exposed to the filament radiation for long time periods (seconds), and a process of multiple absorption and emition events occurs, until the internal energy of the ions is high enough for fragmentation. Computational methods have been implemented from this model allowing for simulation of the dissociation process. For this simulation the ion vibrational spectra, that normally must be obtained from theoretical calculations, is also required, as has been done in this work for some of the studied ions. The method of unimolecular dissociation induced by infrared radiation was applied to the determination of activation and dissociation energies of the molecular ions of acetophenone, p-cymene and cumene. This method also proved to be capable in the differentiation of isomeric structures, and was so applied in the study for the keto-enol isomerization of the acetophenone molecular ion. It was also shown that the method can dissociate the molecular ions of n-butylbenzene an allyl bromide.