The theory of radiative transfer is applied to the problem of multiple wave scattering in a one-dimensional multilayer. A new mathematical model of a multilayer is presented in which both the refractive index and width of each layer are randomized. The layer widths are generated by a new probability distribution which allows for strong layer width disorder. An expression for the transport mean free path of the multilayer is derived based on its single-scattering properties. It will be shown that interference between the field reflected from adjacent layer interfaces remains significant even in the presence of strong layer width disorder. It will be proven that even when the scattering is weak, the field in a random multilayer localizes at certain frequencies. The effect of increasing layer width randomization on this form of localization is quantified. The radiative transfer model of time-harmonic scattering in multilayers is extended to narrow-band pulse propagation in weakly scattering media. The tendency of pulses to broaden in this medium is discussed. A radiative transport model of the system is developed and compared to numerical solutions of the wave equation. It is observed that pulse broadening is not described by simple transfer theory. The radiative transfer model is extended by the addition of a Laplacian term in an attempt to model the effect of ensemble average pulse broadening. Numerical simulation results in support of this proposal are given, and applications for the theory suggested. Finally, the problem of acoustic wave scattering by planar screens is considered. The study was motivated by the idea that multiple scattering experiments may prove possible in a medium composed of such scatterers. Successful multiple scattering in a medium of planar scatterers will depend on the scattering cross-section at angles away from normal incidence. The scattering cross-section is calculated for a circular disc using a new technique for solving the acoustic wave equation on planar surfaces. The method is validated by comparison with available analytic solutions and the geometric theory of diffraction.

The theory of radiative transfer is applied to the problem of multiple wave scattering in a one-dimensional multilayer. A new mathematical model of a multilayer is presented in which both the refractive index and width of each layer are randomized. The layer widths are generated by a new probability distribution which allows for strong layer width disorder. An expression for the transport mean free path of the multilayer is derived based on its single-scattering properties. It will be shown that interference between the field reflected from adjacent layer interfaces remains significant even in the presence of strong layer width disorder. It will be proven that even when the scattering is weak, the field in a random multilayer localizes at certain frequencies. The effect of increasing layer width randomization on this form of localization is quantified. The radiative transfer model of time-harmonic scattering in multilayers is extended to narrow-band pulse propagation in weakly scattering media. The tendency of pulses to broaden in this medium is discussed. A radiative transport model of the system is developed and compared to numerical solutions of the wave equation. It is observed that pulse broadening is not described by simple transfer theory. The radiative transfer model is extended by the addition of a Laplacian term in an attempt to model the effect of ensemble average pulse broadening. Numerical simulation results in support of this proposal are given, and applications for the theory suggested. Finally, the problem of acoustic wave scattering by planar screens is considered. The study was motivated by the idea that multiple scattering experiments may prove possible in a medium composed of such scatterers. Successful multiple scattering in a medium of planar scatterers will depend on the scattering cross-section at angles away from normal incidence. The scattering cross-section is calculated for a circular disc using a new technique for solving the acoustic wave equation on planar surfaces. The method is validated by comparison with available analytic solutions and the geometric theory of diffraction.

The theory of radiative transfer is applied to the problem of multiple wave scattering in a one-dimensional multilayer. A new mathematical model of a multilayer is presented in which both the refractive index and width of each layer are randomized. The layer widths are generated by a new probability distribution which allows for strong layer width disorder. An expression for the transport mean free path of the multilayer is derived based on its single-scattering properties. It will be shown that interference between the field reflected from adjacent layer interfaces remains significant even in the presence of strong layer width disorder. It will be proven that even when the scattering is weak, the field in a random multilayer localizes at certain frequencies. The effect of increasing layer width randomization on this form of localization is quantified. The radiative transfer model of time-harmonic scattering in multilayers is extended to narrow-band pulse propagation in weakly scattering media. The tendency of pulses to broaden in this medium is discussed. A radiative transport model of the system is developed and compared to numerical solutions of the wave equation. It is observed that pulse broadening is not described by simple transfer theory. The radiative transfer model is extended by the addition of a Laplacian term in an attempt to model the effect of ensemble average pulse broadening. Numerical simulation results in support of this proposal are given, and applications for the theory suggested. Finally, the problem of acoustic wave scattering by planar screens is considered. The study was motivated by the idea that multiple scattering experiments may prove possible in a medium composed of such scatterers. Successful multiple scattering in a medium of planar scatterers will depend on the scattering cross-section at angles away from normal incidence. The scattering cross-section is calculated for a circular disc using a new technique for solving the acoustic wave equation on planar surfaces. The method is validated by comparison with available analytic solutions and the geometric theory of diffraction.

The theory of radiative transfer is applied to the problem of multiple wave scattering in a one-dimensional multilayer. A new mathematical model of a multilayer is presented in which both the refractive index and width of each layer are randomized. The layer widths are generated by a new probability distribution which allows for strong layer width disorder. An expression for the transport mean free path of the multilayer is derived based on its single-scattering properties. It will be shown that interference between the field reflected from adjacent layer interfaces remains significant even in the presence of strong layer width disorder. It will be proven that even when the scattering is weak, the field in a random multilayer localizes at certain frequencies. The effect of increasing layer width randomization on this form of localization is quantified. The radiative transfer model of time-harmonic scattering in multilayers is extended to narrow-band pulse propagation in weakly scattering media. The tendency of pulses to broaden in this medium is discussed. A radiative transport model of the system is developed and compared to numerical solutions of the wave equation. It is observed that pulse broadening is not described by simple transfer theory. The radiative transfer model is extended by the addition of a Laplacian term in an attempt to model the effect of ensemble average pulse broadening. Numerical simulation results in support of this proposal are given, and applications for the theory suggested. Finally, the problem of acoustic wave scattering by planar screens is considered. The study was motivated by the idea that multiple scattering experiments may prove possible in a medium composed of such scatterers. Successful multiple scattering in a medium of planar scatterers will depend on the scattering cross-section at angles away from normal incidence. The scattering cross-section is calculated for a circular disc using a new technique for solving the acoustic wave equation on planar surfaces. The method is validated by comparison with available analytic solutions and the geometric theory of diffraction.

Cette thèse vise à évaluer le potentiel d'un nouveau couple cathode / électrolyte pour une application en IT-SOFC (700°C), par le biais de l’élaboration et du test de cellules à anode support de configuration planaire. Les matériaux concernés sont l'électrolyte BaIn0.3Ti0.7O2.85 (BIT07), de structure perovskite, et les nickelates de terres rares Ln2-xNiO4+ (LnN, Ln = La, Nd, Pr) en tant que cathodes ; ces matériaux ont montré des propriétés prometteuses dans des travaux préliminaires effectués à l'IMN et l'ICMCB. La première partie de cette thèse porte sur la mise en place d'un protocole d'élaboration de cellules complètes utilisant des techniques bas coûts et industrialisables (cellules de taille 3 x 3 cm2) : l’anode Ni / BIT07 a été élaborée par coulage en bande, l'électrolyte BIT07 par vacuum slip casting et les cathodes par sérigraphie. Les mesures électrochimiques réalisées sur une première génération de cellules ont mis en évidence la nécessité d'ajouter une couche barrière de GDC entre les cathodes LnN et l'électrolyte BIT07. Les meilleures performances ont été obtenues pour une cellule BIT07 / Ni | BIT07 | GDC | PrN, avec une densité de puissance à 700°C et 0.7 V de 176 mW cm-2 pour une faible résistance de polarisation de 0. 29 Ω cm2. La principale limitation des performances a été identifiée comme étant la résistance interne du banc de test, donnant lieu à des valeurs de résistances séries anormalement élevées. Cette cellule a été opérée avec succès durant plus de 500 heures sous courant, avec néanmoins une vitesse de dégradation extrapolée élevée de l’ordre de 27% / kh. / This thesis aimed at assessing the potential of a novel cathode / electrolyte couple for IT-SOFC applications (700°C), through the elaboration and testing of planar anode-supported cells. The materials involved were the perovskite-structured BaIn0.3Ti0.7O2.85 (BIT07) electrolyte and the rare earth nickelate Ln2-xNiO4+ (LnN, Ln = La, Nd, Pr) cathodes, both materials having shown promising properties in preliminary work done at the IMN and the ICMCB. The first part of this thesis concerned the implementation of a cell elaboration protocol using low-cost and scalable shaping techniques (cell size 3 x 3 cm2); namely, the Ni / BIT07 anodes were elaborated by tape casting, the BIT07 electrolyte by vacuum slip casting and the cathodes by screen printing. Comparison of electrochemical results for a first and second generation of cells highlighted the usefulness of adding a GDC buffer layer in between the LnN cathodes and the BIT07 electrolyte. The best performance has been obtained for a cell BIT07 / Ni | BIT07 | GDC | PrN, with a power density at 700°C and 0.7 V of 176 mW cm-2 for a competitive polarisation resistance of 0.29 Ω cm2. The main limitation of the performance has been determined to be related to the internal resistance of the test setup, giving anomalously high series resistances. This cell has been successfully operated beyond 500 hours under current, although with a fairly high extrapolated degradation rate of 27% / kh.

No description available.

Rapporten behandlar simuleringar, beräkningar och mätningar av HVAC-kablar. En genomgång presenteras av kabelteori samt de olika magnetiska och elektriska effekterna som påverkar skärmströmmarnas storlek. / This report comprises simulations, calculations and measurements of HVAC cables. An introduction to cable theory and a review of the different magnetic and electric effects that has an impact on the amplitude of the screen currents in these cables.

Depuis une vingtaine d'années, des composants électroniques flexibles sont développés. Ces composants étant amenés à se tordre, à s'étirer et à se fléchir au cours de leur utilisation, le développement de composants ayant une bonne fiabilité mécanique est primordial. Ce travail s'est concentré sur les films métalliques d'argent déposés par impression jet d'encre ou sérigraphie sur des substrats de polyimide, servant à l’interconnexion électrique entre composants actifs. Deux mécanismes d’endommagement sont observables dans ces systèmes : la fissuration et le flambement par délaminage.Premièrement, pour caractériser expérimentalement ces deux phénomènes, des tests de traction sont réalisés sous microscope optique, afin de suivre l'évolution des fissures au cours de la déformation et sous interféromètre optique, afin de suivre les cloques de délaminage. Une analyse d'images est réalisée afin d'obtenir l'évolution de l'espacement entre fissures au cours de la déformation. L'existence de deux régimes de fissuration est observée : la fissuration longue et droite pour les films épais et la fissuration courte et en forme de zigzag pour les films minces. Le suivi des profils de cloques permet d'obtenir l'évolution de leur forme au cours de la déformation.Ensuite, afin d'éclairer les observations expérimentales, les phénomènes à l'étude sont modélisés par élément finis. Ainsi l'origine des deux régimes de fissuration est expliquée par un effet géométrique de l'épaisseur du film. Un modèle élastoplastique bidimensionnel de relaxation de contraintes dans le film permet d'obtenir un encadrement de l'espacement entre fissures au cours de la déformation. À partir du suivi des cloques, un modèle tridimensionnel permet de réaliser une identification des paramètres de la zone cohésive à l'interface film/substrat, où une énergie d'adhésion de 2 J.m-2, une contrainte critique de 20 MPa et un paramètre de mixité modale de 0,4 sont déterminés. Ces valeurs sont en accord avec la littérature. / Over the past 20 years, new improvements in materials and processes led to the development of printed flexible electronics. Flexible electronics devices subjected to bending, twisting, or stretching during their lifetime, the development of device with high reliability is therefore of great importance for the efficiency of electrical connection. This work investigates the mechanical reliability of inkjet or screen-printed Ag thin films on polyimide substrates dedicated to the electrical interconnection of active components. Expected mechanical failure modes are film cracking and buckling delamination.First of all, in order to characterized the two mechanisms, tensile tests are performed under an optical microscope to follow cracks and under an optical interferometer to follow buckles. In order to obtain crack spacing evolution during deformation, an image processing is realized. Two types of cracks are observed: long and straight cracking for thick films and small and zigzag shape cracking for thin films. The evolution of buckles shape with imposed tensile deformation is characterized.In a second time, in order to understand experimental observations, mechanical failure modes are analysed with finite elements models. The origin of the two types of cracking are explained by a geometrical effect of film thickness. A elastoplastic shear lag bidimensional model gives upper and lower bonds of crack spacing during deformation. A three-dimensional model allows identification of cohesive zone model parameters at film/substrate interface, from experimental buckle shape. An adhesion energy of 2 J.m-2 , a critical strength of 20 MPa and a mode mixity parameter of 0.4 are determined. These values are in good agreement with literature.

This dissertation examines the as yet untethered practice of the convergence of film and architecture in public municipal spaces against the backdrop of the idea of the relocation of the moving picture. Since this is an interdisciplinary practice whose forms and operations are influenced by a host of dynamics, the initial film perspective is supplemented by related themes from the spheres of architecture, public municipal space, and the organisation of culture and the applied arts, including advertising. The wide range of subjects covered in this dissertation is given focus by narrowly localised research examining the situation in Prague from the 1990s until 2010. Along with the case study, the chapters devoted to the discursive field form a progress report on the situation as regards this particular media practice, the outputs of which are subject to a short half-life that considerably limits the possibility of archiving them. The structure of the case study is derived from a specific classificatory framework and is close to the "catalogue" format, determined by a series of questions - who participated on the convergence of film and architecture and where, when and how. Though a specific segment of time was monitored, it did not remain free of links to previous working methods, historical situations and...

Dans le domaine de la santé, l’analyse de l'haleine expirée offre un outil simple et non invasif pour le diagnostic précoce des maladies. Les capteurs de gaz à base de SnO2 modifies semblent être des dispositifs prometteurs pour détecter les gaz polaires tels que l'ammoniac. Dans cette étude, la fonctionnalisation de la surface de SnO2 a été réalisée afin d'obtenir un capteur de gaz sensible et sélectif à l'ammoniac, qui fonctionne à température ambiante. La première étape de la fonctionnalisation est la fixation covalente d’un film de 3-aminopropyltrethoxysalane (APTES) sur SnO2 en phase vapeur ou liquide. Les caractérisations effectuées par Spectroscopie Infrarouge et Spectrométrie photoélectronique X montrent qu’une quantité plus importante d'APTES a été greffée en phase liquide hydratée. La deuxième étape consiste à fonctionnaliser le SnO2-APTES avec des molécules contenant du chlorure d'acyle avec différents groupes tel que des groupes alkyle, acide et ester. Les capteurs modifiés par des acides et des esters sont sensibles à l’ammoniac entre 0,2 et 10 ppm à température ambiante. Cependant, le SnO2 APTES modifié par l’ester s'est révélé être plus sélectif que le capteur modifié par l'acide pour l’ethanol et le mondxyde de carbone. Ces résultats impliquent que la réponse est générée par les groupes fonctionnels acide et ester, NH3 modifie le moment dipolaire de la couche moléculaire greffée, ce qui entraine une modification de la conductance de SnO2. Le fonctionnement à température ambiante est l'un des avantages de ces capteurs, tout comme leur sélectivité à l'ammoniac en regard d'autres gaz tels que l'éthanol, le monoxyde de carbone et l'acétone. / One of the major challenges in the modern era is how we can detect the disease when we are still feeling healthy via noninvasive methods. Exhaled breath analysis is offering a simple and noninvasive tool for early diagnosis of diseases. Molecularly modified SnO2 sensors seem to be promising devices for sensing polar gases such as ammonia. SnO2 surface functionalization was performed in order to obtain sensitive and selective ammonia gas sensor that operates at room temperature. The first step of functionalization is the covalently attachment of 3-aminopropyltriethoxysilane (APTES) film on SnO2 in vapor or liquid phases. The characterization performed by the Infrared Spectroscopy and X-ray Photoelectron Spectroscopy, show that more APTES were grafted by hydrous liquid phase silanization. The second step was the functionalization of APTES modified SnO2 with molecules having acyl chloride of end functional groups molecules such as alkyl, acid and ester groups. Pure SnO2 and APTES modified SnO2 sensors did not show any significant sensitivity to ammonia (0.2-100 ppm) at 25 °C. On the contrary, acid and ester modified sensors are sensitive to ammonia between 0.2 and 10 ppm at room temperature. However, ester modified SnO2 was more selective than acid modified sensor regarding the ethanol and carbon monoxide gases. Ammonia variates the attached molecular layer’s dipole moment which leads to change in SnO2 conductance. Working at ambient temperature is also one of the advantages of these sensors in addition to the selectivity to ammonia regarding other gases such as ethanol, carbon monoxide and acetone.