Dans ce travail nous avons réalisé une étude expérimentale du mouillage réactif dans l'objectif de comprendre la relation existant entre l'étalement du liquide et la formation d'une nouvelle phase à l'interface liquide/solide. Les systèmes modèles choisis pour cette l'étude sont composés d'un substrat de carbone (carbone vitreux ou graphite monocristallin) et d'un alliage liquide constitué d'une matrice non-réactive (essentiellement Cu mais aussi Ni, Ge et Sn) et d'un soluté réactif formant un carbure mouillable (Si, Cr, B et Ti). Ce choix nous a permis d'obtenir les deux types d'étalement réactif, à contrôle chimique et à contrôle diffusionnel. Le suivi des cinétiques d'étalement a nécessité la mise en œuvre de méthodes spécifiques (goutte "déposée" et goutte "transférée") permettant de découpler le processus de formation d'une goutte et celui de son étalement sur un substrat. Le contrôle de l'état de surface des substrats et la caractérisation des interfaces ont été réalisés par différentes techniques: profilométrie optique haute résolution, microscopie optique, microscopie électronique à balayage, micronanalyse X et spectroscopie d'électons Auger. Pour les cinétiques d'étalement à contrôle chimique nous montrons que dans le cas général, le mouillage a lieu en une seule étape à vitesse d'étalement décroissante et que cette vitesse n'est fonction que de l'angle de contact instantanné. Nous définissons cet angle comme un angle d'équilibre reflétant continuellement le taux de recouvrement de l'interface par le produit de réaction à la ligne triple. Enfin, nous montrons que cinétique réactionnelle et cinétique d'étalement sont contrôlées par la dissolution du substrat. Pour les cinétiques à contrôle diffusionnel nous réalisons une modélisation numérique permettant de prendre en compte dans la description du mouillage la diffusion et la réaction interfaciale ayant lieu en arrière de la ligne triple, ou encore le phénomène d'évaporation/condensation pouvant intervenir en avant de la ligne triple.

Par évaporation sous vide avec un laser pulse, on se propose de fabriquer des couches minces de matériaux varies et des multicouches utilisables pour la réalisation de miroirs a rayons x-uv; les paramètres pour la réflectivité des empilements que nous essayons d'améliorer sont: la pureté, l'homogénéité d'épaisseur, la compacité et la planéité des interfaces des différentes couches obtenues. Nous avons mis en place un dispositif qui utilise un laser nd-yag pulse ayant une densité de puissance au niveau de la cible supérieure a 100 millions de watts par centimètre carre. Un déplacement dans deux directions orthogonales assure un balayage uniforme du faisceau de la cible. L'épaisseur des couches est contrôlée pendant le dépôt par une microbalance a quartz. L'ensemble est gèré par un micro-ordinateur permettant le pilotage automatique de la fabrication de couches simples et multicouches. Pour la plupart des matériaux étudiés, les couches minces fabriquées ont une densité du matériau massif. La rugosité aux interfaces (c sur w par exemple) est souvent meilleure que celle obtenue dans le cas d'une évaporation thermique classique. Il reste a résoudre les problèmes d'homogeneite d'épaisseur que nous avons mis en évidence. Les projections de gouttelettes de matériau durant l'évaporation posent un problème, particulièrement aigu dans le cas du silicium, ou la surface des couches présente des aspérités sous forme de gouttelettes solidifiées .

<p>This thesis work has been performed at the department of diagnosis and dependability at Volvo Car Company, Torslanda. The background of this project is based on interest in ascertaining how different factors possibly can affect a diagnosis method, which has been developed to find leaks in the fuel tank and evaporation system. According to the OBD II requirements leaks with an orifice diameter larger or equal to 0,5 mm, must be detected. The idea of the diagnosis method is to create an over pressure in the system with an air-pump. The current through the pump is measured and correlates to the power consumed by the pump. As the power is a function of the pressure difference over the pump, the pump current correlates to the pressure in the tank. Thus, the pump current can be used as a measure of the impenetrability. Changes in the system pressure, not caused by the pump, are accordingly disturbances to the method. </p><p>The object of this work was to develop mathematical models, describing the lapse where the system is pressurized by the pump under the influence of different physical factors. The model is for instance considering variations in temperature and height, flow resistance in lines and valves, component characteristics, fuel evaporation, leaks etc. Furthermore the pump current is treated by the diagnosis evaluation algorithm with purpose to judge whether there is a leak in the system. </p><p>The model has been implemented in Matlab/Simulink and it can consequently be used in dynamic simulations according to the over pressure leakage detection concept. Numerical experiments can be done in purpose to examine how changes in environmental conditions or component characteristics will affect the diagnosis method. Good agreement has been found between measurements and simulated results. The diagnosis function produces correct decisions under different conditions with disparity in leak sizes, additionally confirming the reliability of the model.</p>

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 113-121).

<p>The objective of this project is to study the production of Li, Be and B isotopes emitted in the interaction of 12C with 12C at incident energies of 200 and 400 MeV.<br /> The energies of these produced fragments were measured with a detector telescope consisting of two silicon detectors at the incident energy of 200 MeV while a third silicon detector was added for the measurements at 400 MeV.</p>

Quaternary cubic (TixCr1 − xAl~ 0.60)1 N1 coatings with 0 &lt; x &lt; 0.33 have been grown using reactive cathodic arc evaporation. When adding Ti the hardness was retained after annealing up to 1100 °C which is a dramatic improvement compared to CrAlN coatings. The coatings showed an age hardening process caused by spinodal decomposition into coherent TiCr- and Al-rich cubic TiCrAlN domains and the formation of hexagonal AlN precipitates and cubic TiCrN domains in the vicinity of the grain boundaries. The improved hardness was attributed to the stabilization of the cubic structure suppressing the formation and growth of hexagonal AlN. Furthermore, the presence of Ti atoms generated incoherent nanometer-sized crystallites within the hexagonal AlN precipitates disrupting the hexagonal lattice during the coarsening process. The addition of Ti promoted the formation of a TiO2 layer over Al2O3 resulting in a lower oxidation resistance. However, by tuning the composition it is possible to design coatings to have both good oxidation resistance and good high temperature mechanical stability. / <p>Funding Agencies|SSF project Designed multicomponent coatings, MultiFilms||</p>

<p>This research investigated the nature, source and the spatial variation of the salinity of the water used for irrigation in the urban farming area of Philippi, which lies in the Cape Flats region of the Cape Town Metropolitan Area, South Africa. The irrigation water is mainly drawn from the Cape Flats aquifer, and pumped into ponds for eventual crop irrigation. Water samples were collected in summer and in winter from fifteen selected sites using standard water sampling procedures. Each site consisted of one borehole and one pond. The samples were routinely analyzed for salinity levels, and concentrations of major and minor ions. From the same boreholes and ponds, water was sampled in summer for isotope analysis to assess effects of evaporation on the water quality and salinity. Descriptive statistics were used to display the variation in range of specific ions in order to compare them with the recommended ranges. Geographical Information Systems analysis described the spatial distribution of the salinity across the study area, and hydrogeochemical analysis characterized the various waters and detected similarities between the water samples in the study area and other waters found in the Cape Flats region. In addition, the US salinity diagram classification of irrigation water developed by Richards (1954) was used to assess the current suitability of groundwater and pond water samples collected during the entire sampling period for irrigation activities. The research indicated that the concentrations of some ions such as chloride, nitrate, potassium and sodium exceeded in places in the study area, the target range values set by the Department of Water Affairs and Forestry (DWAF, 1996) and the Food and Agriculture Organization (Ayers and Westcot, 1985). It revealed that borehole and pond water were mostly brackish across the area regarding their total dissolved salts content, and fresh water was only found in the middle part of the study area. The research found that sea water does not intrude into the aquifer of the study area, and the accumulation of salts in groundwater and soil in the study area is mainly due to the agricultural activities and partially due to the natural movement of water through the geological formation of the Cape Flats region. The conceptual model of the occurrence of the salinization process supported these findings. From this investigation it is understood that the groundwater and pond water in the study area were generally suitable for irrigation purposes but they have to be used with caution as the vegetables are classified as sensitive and moderately sensitive to salt according to DWAF Irrigation water guidelines (1996). The quality of these waters was mainly affected by the land use activities.</p>

Cette thèse est centrée sur le développement d'outils expérimentaux permettant de mieux caractériser l'étude du couplage entre l'évaporation de gouttelettes et un écoulement turbulent gazeux environnant. Dans notre étude on cherche à se placer dans un régime de couplage fort entre les gouttelettes évaporantes et la turbulence. Dans ce régime peu renseigné dans la littérature, les gouttelettes se trouvent dans un régime intermédiaire entre le régime de traceur et le régime inertiel. Dans un premier temps nous présentons un dispositif expérimental capable de générer une turbulence homogène isotrope avec de fortes fluctuations de vitesse, ainsi que la réalisation de l'injection de gouttelettes initialement monodisperses. Puis, l'instrumentation Lagrangienne développée (en collaboration avec le laboratoire Hubert Curien de St Etienne) : l'holographie numérique en ligne, est ensuite testée et validée pour un fluide non évaporant. Une méthode de tracking des gouttelettes a été mise au point afin de reconstruire les trajectoires des gouttelettes dans le volume turbulent homogène isotrope. La précision obtenue sur les diamètres (2% pour des gouttes de 60 μm) vient complètement valider cette métrologie pour l'étude de l'évaporation. Les premiers résultats obtenus avec des gouttelettes évaporantes de fréon R114 font apparaître la visualisation, à notre connaissance inédite, des sillages évaporants. Une première reconstruction de trajectoire avec l'évolution du diamètre de la goutte au cours du temps est enfin présentée.

The convective mass transfer coefficient is determined for evaporation in a horizontal rectangular duct, which forms the test section of the transient moisture transfer (TMT) facility. In the test facility, a short pan is situated in the lower panel of the duct where a hydrodynamically fully developed laminar or turbulent airflow passes over the surface of the water. The measured convective mass transfer coefficients have uncertainties that are typically less than ±10% and are presented for Reynolds numbers (ReD) between 560 and 8,100, Rayleigh numbers (RaD) between 6,100 and 82,500, inverse Graetz numbers (Gz) between 0.003 and 0.037, and operating conditions factors (H*) between -3.6 and -1.4. The measured convective mass transfer coefficients are found to increase as ReD, RaD, Gz and H* increase and these effects are included in the Sherwood number (ShD) correlations presented in this thesis, which summarize the experimental data.<p> An analogy between heat and mass transfer is developed to determine the convective heat transfer coefficients from the experimentally determined ShD correlations. The convective heat transfer coefficient is found to be a function of ShD and the ratio between heat and moisture transfer potentials (S*) between the surface of the water and the airflow in the experiment. The analogy is used in the development of a new method that converts a pure heat transfer NuD (i.e., heat transfer with no mass transfer) and a pure mass transfer ShD (i.e., mass transfer with no heat transfer) into NuD and ShD that are for simultaneous heat and mass transfer. The method is used to convert a pure heat transfer NuD from the literature into the NuD and ShD numbers measured in this thesis. The results of the new method agree within experimental uncertainty bounds, while the results of the traditional method do not, indicating that the new method is more applicable than the traditional analogy between heat and mass transfer during simultaneous heat and mass transfer.<p>A numerical model is developed that simulates convective heat and mass transfer for a vapor permeable Tyvek® membrane placed between an airflow and liquid water. The boundary conditions imposed on the surfaces of the membrane within the model are typical of the conditions that are present within the TMT facility. The convective heat and mass transfer coefficients measured in this thesis are applied in the model to determine the heat and moisture transfer through the membrane. The numerical results show that the membrane responds very quickly to a step change in temperature and relative humidity of the air stream. Since the transients occur over a short period of time (less than 1 minute), it is feasible to use a steady-state model to determine the heat and mass transfer rates through the material for HVAC applications.<p>The TMT facility is also used to measure the heat and moisture transfer through a vapor permeable Tyvek® membrane. The membrane is in contact with a water surface on its underside and air is passed over its top surface with convective boundary conditions. The experimental data are used to verify the numerically determined moisture transfer rate through the Tyvek® membrane. The numerical model is able to determine the mass transfer rates for a range of testing conditions within ±26% of the experimental data. The differences between the experiment and the model could be due to a slightly different mass transfer coefficient for flow over Tyvek® than for flow over a free water surface.

This research explores the thermal stability of ZrCrAlN material system. For this purpose fourteen different compositions of ZrCrAlN coatings were deposited onto tungsten carbide substrates by using reactive cathodic arc evaporation. These compositions were further annealed at 800oC, 900oC, 1000oC and 1100oC temperatures. EDS was employed to specify the compositions. The crystal structure of the coatings were analysed by XRD, and the hardness of these coatings was determined by Nanoindentation. The experimental findings reported a significant age hardening of Zr0.16Cr0.12Al0.72N and a delayed h-AlN formation in Zr0.07Cr0.40Al0.52N. ZrCrAlN was thus proved to be thermally stable. / Multifilms,A4:2 Growth and characterization of Multicomponent Nitrides by Magnetron Sputtering and Arc evaporation