Les nickelates de terres rares de formule générale Ln2NiO4+δ (Ln = La, Pr, ou Nd) suscitent un fort intérêt, aussi bien au niveau théorique qu’au niveau expérimental, en raison notamment de leur propriétés thermo-radiatives exceptionnelles de type corps noir. De nombreux industriels s’intéressent ainsi aux émetteurs thermiques par émission infrarouge, afin de remplacer le procédé de chauffage classique par convection. Le pouvoir émissif de ces matériaux est intimement lié à leurs propriétés intrinsèques et extrinsèques. Les propriétés intrinsèques d’un matériau correspondent à sa composition chimique, son épaisseur, et ses indices optiques, tandis que les propriétés extrinsèques dépendent plutôt de sa texture (rugosité, porosité, taille de grains et de pores, joints de grain, etc.), et la présence éventuelle d’impuretés. Des revêtements de Pr2NiO4+δ ont été déposés sur substrats polycristallins et monocristallins par pulvérisation cathodique magnétron radiofréquence, combiné avec un traitement thermique approprié à 1100◦C. L’analyse par diffraction des rayons X a révélé la composition biphasique des revêtements, avec la présence d’une surstoechiométrie en oxygène. La morphologie des surfaces a été étudiée par MEB, AFM et profilométrie, révélant l’aspect rugueux et poreux des couches déposées. Les propriétés thermo-radiatives ont été étudiées par spectroscopie infrarouge. L’émissivité spectrale normale a été mesurée de 300 K jusqu’à 1400 K, confirmant les fortes propriétés d’émissivité des revêtements de Pr2NiO4+δ , même pour une faible épaisseur de 1,5 μm. Dans le moyen infrarouge, une émissivité totale de 0,87 a été obtenue pour une épaisseur de 2,8 μm. / Rare earth nickelate oxides Ln2NiO4+δ (Ln = La, Pr, and Nd) have attracted considerable interest for both theoretical and experimental studies especially due to their pseudo-high black body behavior. Advanced industry takes a particular interest in applications based on infrared radiation heater, which tend to replace the classical heating convection. Thermal radiative properties of materials are intimately related to their intrinsic and extrinsic characteristics. Intrinsic properties concern chemical composition, thickness layer and complex refractive index, while extrinsic properties refer to the texture (roughness, porosity, grain and pore sizes and grain boundaries) and the presence of impurities. Pr2NiO4+δ coatings have been obtained on both polycrystalline and monocrystalline substrates by combining RF magnetron co-sputtering with an appropriate heat treatment at 1100◦C. X-ray diffraction spectroscopy analysis revealed a biphasic Pr2NiO4+δ compound, with an oxygen over-stoichiometry. The surface analysis was probed by SEM, AFM and profilometry, and showed a rough and porous granular aspect for all the deposited layers. Thermal radiative properties were studied by infrared optical spectroscopy. The normal spectral emissivity from 300 K up to 1400 K confirmed the high emissive properties of the Pr2NiO4+δ coatings, even for thicknesses down to 1,5 μm. A total normal emissivity of 0,87 in the mid-infrared range is obtained for the 2,8 μm coating thickness.

Ces travaux sont issus d’une thèse CIFRE et de la collaboration entre la société Viessmann Faulquemont et le laboratoire de recherche l’Institut Jean Lamour. Ayant pour objectif de fortement réduire les problèmes liés aux hautes températures de stagnation dans les panneaux solaires thermiques, nous présentons une nouvelle génération d’absorbeur solaire intelligent à base de dioxyde de vanadium. Le dioxyde de vanadium, noté VO2, est un matériau présentant une transition métal-isolant (MIT) à une température critique (Tc) de 68°C. Cette transition s’accompagne d’une modification de la structure cristallographique. Le VO2 se trouve sous une forme monoclinique VO2(M) à basse température, et sous une forme rutile VO2(R) à haute température. Ce changement de structure s’accompagne d’une forte modification des propriétés optiques. La synthèse de ces films est réalisée à partir d’une couche de vanadium métallique déposée par pulvérisation. Un recuit d’oxydation-cristallisation est ensuite effectué pour obtenir une couche d’environ 400 nm de dioxyde de vanadium. Afin d’optimiser et d’augmenter la variation d’émissivité (Δε), la température et la durée du recuit sont étudiées. Dans un second temps, un dopage aluminium est réalisé afin d’augmenter l’effet de la transition thermochrome. Après optimisation, le passage au niveau industriel est un succès et des prototypes de taille 1 sont réalisés à partir de la couche thermochrome et de la couche standard afin d’être comparés dans des conditions normales d’utilisation / This work is a CIFRE thesis between VIESSMANN Faulquemont SAS society and the laboratory Institut Jean Lamour. In order to strongly reduce the problems associated with high stagnation temperature, we present a new generation of solar absorbent layers based on a smart thermochromic vanadium dioxide thin film. Vanadium dioxide (VO2) is a material which exhibit a metal insulator transition (MIT) at a critical temperature of 68°C (Tc). The transition is accompanied by a change in crystallographic structure VO2(M), while a rutile-like structure VO2(R) is obtained at high temperature. This structural change induces a drastic modification of the optical properties. The synthesis of vanadium-based films is performed using magnetron sputtering. We proceed to a subsequent annealing in air to form crystalline films of about 400 nm thickness. In order to increase the thermochromic effect of our thin film (Δε) we study the temperature and duration of the annealing. In a second time we try to increase the emissivity switch between the low and high temperature phase by adding an aluminum doping. After optimization, scale up have been successfully done and the optimized parameters have been used to build a prototype of thermochromic selective layer that has been compared to the standard industrial solar absorber

La télédétection en imagerie hyperspectrale infrarouge thermique est l'étude d'images en luminance, acquises depuis un avion ou un satellite dans le domaine spectral de l'infrarouge thermique. Ces images sont liées à l'émissivité et à la température, estimées par les méthodes de découplage température/émissivité (T/E), ainsi qu'à l'abondance, estimée par les méthodes de démélange, des matériaux présents dans la scène. Si les méthodes de découplage T/E ont été largement étudiées, les méthodes de démélange dans ce domaine spectral restent peu explorées : c'est l'objectif de cette thèse. Pour cela, nous avons mis en place trois stratégies de démélange. Dans un premier temps, le démélange est effectué sur les luminances. Cette stratégie donne globalement de bons résultats mais est relativement sensible aux variations spatiales de la température. La deuxième stratégie, démélangeant à partir des estimations d'émissivité des méthodes de découplage T/E, s'affranchit de cette variation spatiale mais donne des résultats plus bruités. Enfin, une méthode de démélange basée sur l'estimation conjointe de la température et des abondances a été élaborée. Cette méthode s'appelle Thermal Remote sensing Unmixing for Subpixel Temperature (TRUST) et donne de meilleurs résultats que la première stratégie tout en étant robuste aux variations spatiales de la température. / Thermal hyperspectral remote sensing provides information about materials from the measured radiance image. It is achieved using temperature and emissivity separation (TES) methods, estimating the emissivity and the temperature of the materials, and using unmixing methods, estimating their abundances. TES methods have been well investigated while too few studies have been working on unmixing in thermal infrared domain : this is the objective of this PhD. Therefore, three strategies have been studied. First, the unmixing is applied on radiance. It achieves good results but depends on the spatial variation of temperature. Applying the unmixing on the emissivities, estimated using the TES methods, gets rid of the spatial variation of temperature but provides a noisy abundance estimation. Eventually, a new method called Thermal Remote sensing Unmixing for Subpixel Temperature (TRUST) is designed to jointly estimate the abundance and the temperature of materials within the pixels. It gives better results than the first strategy and is more robust to spatial variation of temperature.

The work is focused on research and development of a suitable method for creating a selective emitter for the visible and near infrared region so that they are able to work optimally together with silicon photovoltaic cells in a thermophotovoltaic system. The aim of the work was to develop a new method of creating very fine structures outside the current standard, which will increase the emissivity of the base material to meet the needs of a selective emitter for the VID and NIR region. The methods available to us for the creation of structures were chosen, from which we eliminated all unsuitable ones and we introduced the optimal procedure and parameters for their creation for the selected method. In this work, we focused on both ceramic and metallic materials, whose heat resistance and selective properties are key to this work. Part of the development of the emitter structures was also the need for pretreatment of the substrate itself, where great emphasis was placed on the purity of materials and surface roughness. Since ceramic materials cannot achieve a surface roughness so low that the desired structures can be formed, these materials have been purposefully used primarily for the purpose of combining the base material with thin layers of other high temperature material. Their compatibility and suitability were verified in terms of adhesion and subsequent heat resistance. The main material for the formation of fine structures was purposefully chosen tungsten, for which we verified the influence of the formed structure on the emissivity as well as the thermal stability during long-term exposure to high temperatures. The work thus represents not only a new method of creating very fine structures, which are not normally formed in such subtlety, but also opens the way to new possibilities of combining more materials to achieve the required selectivity of the thermophotovoltaic emitter.

This diploma thesis deals with calculation methods of heat exchanger with cross-flow tube bundle. The first part of the thesis contains summary of generally known basic calculation relations used in calculations of heat exchangers and a detailed description of a given heat exchanger.The second part of the thesis provides a description of available calculation methods of a given aparatus required for its thermal and hydraulic calculation. The final part describes application POST in 1.0 which has been formed on the basis of these calculation methods. Using this application check calculation of exchanger with cross-flow tube bundle was carried out and gained figures compared with results gained by means of professional calculation program HTRI.

This work deals with the issue of emissivity and its impact on the heat dissipation.The first part describes the basics of thermal management, the issue of emissivity and its measurement. In the second, experimental part, are dedicated the emissivity values of examined specimens. These values are then used as initial conditions for the thermal simulation. In the last part are compared the measured results and the simulated results and is evaluated the impact of emissivity for the heat dissipation.

A textura e o conteúdo do carbono orgânico (CO) influenciam na resposta espectral dos solos. O estudo desses atributos é de grande importância para a preservação e o manejo adequado da terra na busca de uma agricultura sustentável. O uso de sensores de laboratório e satélites tem se mostrado como uma ferramenta no auxílio para o estudo destes, porém a análise dos atributos do solo com esses sensores tem focado principalmente nas regiões do espectro eletromagnético do visível (Vis), infravermelho próximo (NIR) e infravermelho de ondas curtas (SWIR), com poucos estudos no infravermelho médio (MIR). O objetivo deste trabalho foi identificar o padrão espectral do solo com diferentes granulometrias (areia e argila) e teores de CO utilizando sensores de laboratório e satélite na região do MIR, especificamente na faixa do infravermelho termal (TIR). O estudo teve uma avaliação qualitativa e quantitativa da argila, CO e das frações de areia (fina e grossa). A área de estudo está localizada na região de Piracicaba, São Paulo, Brasil. Foram coletadas 150 amostras de solo a uma profundidade de 0-20 cm. A textura do solo foi determinada pelo método da pipeta e a porcentagem de CO via combustão seca. Dados espectrais em refletância e emissividade (ε) foram adquiridos com o sensor Fourier Transform Infrared (FT-IR) Alpha (Bruker optics Corporation). Uma imagem \"ASTER_05\" foi adquirida em 15 de julho de 2017 em valores de ε. As amostras foram separadas por classes texturais e o comportamento espectral no TIR foi descrito. Os dados obtidos pelo sensor de laboratório foram reamostrados para as bandas do sensor de satélite. O comportamento entre os espectros de ambos sensores foi semelhante e teve correlação significativa com os atributos estudados, principalmente para areia. Para os modelos de regressão por mínimos quadrados parciais (PLSR), foram utilizadas seis estratégias (MIR, MIR_ASTER, ASTER, Termal, Termal IDC e MIR IDC) que consistiram no uso de todas as bandas de sensores, ou pela seleção das mesmas que apresentaram as correlações mais significativas com cada um dos atributos. Os modelos apresentaram um bom desempenho na predição de todos os atributos usando o MIR inteiro. No TIR, o modelo para areia total e para as frações fina e grossa foi bom. No caso dos modelos criados com os dados do sensor ASTER, não foram tão promissores quanto os de laboratório. O uso de bandas específicas ajudou a estimar alguns atributos no MIR e no TIR, aumentando o desempenho preditivo melhorando a validação dos modelos. Portanto, a discriminação dos atributos do solo com sensores de satélite pode ser melhorada com a identificação de bandas específicas, como observado nos resultados com sensores de laboratório. / Soil texture and organic carbon (OC) content influence its spectral response. The study of these attributes is relevant for the preservation and proper management of land in pursuit of a sustainable agriculture. Laboratory and satellite sensors have been applied as a useful tool for studying soil attributes, but their analysis with these sensors has mainly focused on the visible (Vis), near infrared (NIR) and shortwave infrared (SWIR) regions of the electromagnetic spectrum, with few studies in the Medium Infrared (MIR). The objective of this study was to identify the spectral pattern of soils with different granulometry (sand and clay) and OC content using laboratory and satellite sensors in the MIR region, specifically in the Thermal Infrared (TIR) range. This study had qualitative and quantitative analyses of clay, OC and sand fractions (fine and coarse). The study area is located in the region of Piracicaba, São Paulo, Brazil. 150 soil samples were collected at a depth of 0-20 cm. Soil texture was determined by the pipette method and the percentage of OC via dry combustion. Reflectance and emissivity (ε) spectral data were obtained with the Fourier Transform Infrared (FT-IR) Alpha sensor (Bruker Optics Corporation). An image \"ASTER_05\" from July 15, 2017 was acquired with values of ε. Samples were separated by textural classes and the spectral behavior in the TIR region was described. The data obtained by the laboratory sensor were resampled to the satellite sensor bands. The behavior between spectra of both sensors was similar and had significant correlation with the studied attributes, mainly sand. For the partial least squares regression (PLSR) models, six strategies were used (MIR, MIR_ASTER, ASTER, Thermal, Thermal IDC and MIR IDC), which consisted in the use of all sensors bands, or by the selection of bands that presented the most significant correlations with each one of the attributes. Models presented a good performance in the prediction of all attributes using the whole MIR. In the TIR, models for total sand content and for fine and coarse fractions were good. In the case of models created with ASTER sensor data, they were not as promising as those with laboratory data. The use of specific bands was useful in estimating some attributes in the MIR and TIR, improving the predictive performance and validation of models. Therefore, the discrimination of soil attributes with satellite sensors can be improved with the identification of specific bands, as observed in the results with laboratory sensors.

Halbleiterlaser stellen mit über 70% Wirkungsgrad einzigartig effiziente Lichtquellen dar. Dennoch ist ihre zuverlässige Nutzung, insbesondere im Bereich hoher Leistungsdichten, von thermischen Limitierungen geprägt. Einen grundlegenden Beitrag zu deren physikalischen Verständnis leistet die Analyse der thermischen Eigenschaften und Degradationsprozesse solcher Bauelemente. In dieser Arbeit wird hierzu die Thermographie als innovative Analysemethode untersucht. Das Plancksche Strahlungsgesetz erlaubt die radiometrische Ermittlung der Temperatur. Die wichtige physikalische Kenngröße Emissivität wird in dieser Arbeit für Halbleiter und Halbleiterlaserstrukturen spektral gemessen und auf fundamentale physikalische Eigenschaften zurückgeführt. Auf dieser Grundlage werden methodische Aspekte der Thermographie diskutiert, welche durch den thermischen Hintergrund und die teilweise Transparenz der Halbleitermaterialien geprägt sind. Die daraus folgenden analytischen Fähigkeiten erlauben unter anderem die orts- und zeitaufgelöste Bestimmung der thermischen Eigenschaften von komplexen Hochleistungslasern unterschiedlichster Bauart. Darüber hinaus ermöglicht die Kenntnis der beteiligten thermischen Zeitkonstanten die Extraktion von lokalen Überhöhungen in der Infrarotemission, deren Zusammenhang zur Degradation der Bauelemente untersucht wird. Eine grundsätzliche Begrenzung der Ausgangsleistung ist durch einen abrupten Degradationsprozess gegeben, welcher maßgeblich durch eine Reabsorption der Laserstrahlung an der Frontfacette verursacht wird. Mithilfe einer kombinierten Thermographie-Nahfeld-Messung wird dieser Prozess orts- und zeitaufgelöst analysiert. Die Erweiterung des Messfensters zu kürzeren Wellenlängen hin erlaubt die Detektion strahlender Übergänge unter Einbeziehung von Defektzentren welche als strahlende Signaturen von graduellen Degradationsprozessen aufzufassen sind. / Semiconductor lasers are unequaled efficient light sources, reaching efficiencies of more than 70%. Nevertheless, thermal limits govern their reliable application, in particular in the field of high power densities. The analysis of thermal properties and degradation processes in such devices contributes essentially to the understanding of these limits. This work exploits thermography as an innovative analytical technique for such purpose. Planck''s law allows for a radiometric detection of temperatures. In this work, the important physical parameter emissivity is measured spectrally resolved for both semiconductors and semiconductor laser structures and is related to fundamental physical properties. Based on that, methodological aspects are discussed, which are affected on the one hand by the omnipresent thermal radiation and on the other hand by the partial transparency of the semiconductor materials. The resulting analytical capacities allow, for instance, for the determination of the thermal properties of complex high-power lasers of a wide range of different designs in a spatio-temporally resolved fashion. Furthermore, does the knowledge of the involved thermal time constants allow for an extraction of localized peaks of the infrared emission that is analyzed for its relationship with device degradation. The output power of high-power devices is fundamentally limited by the catastrophic optical damage, an abrupt degradation process that is induced significantly by reabsorption of laser radiation at the front facet. This process is analyzed spatio-temporally resolved with help of a combined thermography and optical near-field technique. Extending the detection range down to shorter wavelengths allows for imaging of radiative transitions that are related to defect centers, which are interpreted as radiative signatures of gradual device degradation processes.

L'objectif de cette thèse est la modélisation du rayonnement thermique directionnel des surfaces et de la correction angulaire sur la LST par des méthodes empiriques et physiques ainsi que l'analyse de validation sur le terrain. L'émissivité directionnelle des surfaces naturelles a été obtenue à partir du produit émissivité MODIS et est ensuite utilisée dans l'algorithme de split-window de correction angulaire sur la LST. Les modèles de paramétrage de l'émissivité directionnelle et du rayonnement thermique ont été développés. En ce qui concerne les pixels non iso-thermiques, la méthode de jour-TISI a été proposée pour obtenir l'émissivité directionnelle et la température effective à partir de données multi-angulaires infrarouges médian et thermique. Cela a été validé à l'aide de données aéroportée. Le modèle de noyaux Kernel BRDF a été vérifié dans le domaine de l'infrarouge thermique et son extension a servi à la normalisation angulaire de la LST. Un nouveau modèle, FovMod, qui concerne l'empreinte du capteur au sol, a été développé pour simuler la température de brillance directionnelle de couvert végétal en rang. Basé sur le résultat de la simulation de FovMod, une empreinte optimale pour la validation de champ de vue a été obtenue. Cette thèse a étudié systématiquement le rayonnement thermique directionnel et les corrections angulaires sur la température de surface et ses résultats amélioreront la précision sur la température et émissivité à partir de données de télédétection. Ils fourniront également des indices pour la conception de capteurs infrarouges thermiques multi-angulaires aéro/spatio portés et également pour la mesure au sol des paramètres de surface. / The aim of this thesis is the modeling of surface directional thermal radiation and angular correction on the LST by using empirical and physical methods as well as the analysis of field validation. The work has conducted to some conclusions. The directional emissivity of natural surfaces was obtained from MODIS emissivity product and then used in the split-window algorithm for angular correction on LST. The parameterization models of directional emissivity and thermal radiation were developed. As for the non-isothermal pixels, the daytime-TISI method was proposed to retrieve directional emissivity and effective temperature from multi-angular middle and thermal infrared data. This was validated using an airborne dataset. The kernel-driven BRDF model was checked in the thermal infrared domain and its extension was used to make angular normalization on the LST. A new model, namely FovMod that concerns on the footprint of ground sensor, was developed to simulate directional brightness temperature of row crop canopy. Based on simulation result of the FovMod, an optimal footprintfor field validation of LST was obtained. This thesis has systematically investigated the topic of directional thermal radiation and angular correction on surface temperature and its findings will improve the retrieval accuracy of temperature and emissivity from remotely sensed data and will also provide suggestion for the future design of airborne or spaceborne multi-angular thermal infrared sensors and also for the ground measurement of surface parameters.

Les travaux présentés dans cette thèse portent sur l’imagerie computationnelle active et passive en micro-ondes. L’utilisation d’une cavité chaotique comme composants compressif est étudiée tant théoriquement (modèle mathématique, résolution algorithmique du problème inverse) et expérimentalement. L’idée sous-jacente est de remplacer un réseau d’antennes par une unique cavité réverbérante dont un réseau d’ouvertures sur la face avant permet de coder l’information spatiale d’une scène dans la réponse temporelle de la cavité. La réverbération des ondes électromagnétique à l’intérieur de la cavité fournit les degrés de liberté nécessaires à la reconstruction d’une image de la scène. Ainsi il est possible de réaliser en temps réel une image haute-résolution d’une scène à partir d’une unique réponse impulsionnelle. Les applications concernent la sécurité ou l’imagerie à travers les murs. Dans ce travail, la conception et la caractérisation d’une cavité chaotique ouverte sont effectuées. L’utilisation de ce dispositif pour réaliser en actif des images de cibles de diverses formes est démontrée. Le nombre de degrés de liberté est ensuite amélioré en modifiant les conditions aux limites grâce à l’ajout lampes fluorescentes. L’interaction des ondes avec ces éléments plasma permet de créer de nouvelles configurations de la cavité, améliorant ainsi la résolution des images. L’imagerie compressive est ensuite appliquée à la détection et localisation passive du rayonnement thermique naturel de sources de bruit, à partir de la corrélation des signaux reçus sur deux voies. Enfin, une méthode novatrice d’imagerie interférométrique de cibles est présentée. Elle est basée sur la reconstruction de la réponse impulsionnelle entre deux antennes à partir du bruit thermique micro-ondes émis par un réseau de néons. Ces travaux constituent une avancée vers les systèmes d’imagerie futurs. / The broad topic of the presented Ph.D focuses on active and passive microwave computational imaging. The use of a chaotic cavity as a compressive component is studied both theoretically (mathematical model, algorithmic resolution of the inverse problem) and experimentally. The underlying idea is to replace an array of antennas with a single reverberant cavity with an array of openings on the front panel that encodes the spatial information of a scene in the temporal response of the cavity. The reverberation of electromagnetic waves inside the cavity provides the degrees of freedom necessary to reconstruct an image of the scene. Thus it is possible to create a high-resolution image of a scene in real time from a single impulse response. Applications include security or imaging through walls. In this work, the design and characterization of an open chaotic cavity is performed. Using this device, active computational imaging is demonstrated to produce images of targets of various shapes. The number of degrees of freedom is further improved by changing the boundary conditions with the addition of commercial fluorescent lamps. The interaction of the waves with these plasma elements allows new cavity configurations to be created, thus improving image resolution. Compressive imaging is next applied to the passive detection and localization of natural thermal radiation from noise sources, based on the correlation of signals received over two channels. Finally, an innovative method of interferometric target imaging is presented. It is based on the reconstruction of the impulse response between two antennas from the microwave thermal noise emitted by a network of neon lamps. This work constitutes a step towards for future imaging systems.