A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 2014. / The aim of this dissertation was to determine the likely impacts that planting woodlands would have on the storage, transport and discharge of mine water and contaminants, over a plume originating from the West Complex tailings storage facility within the Vaal River mine lease. The hydrological model MIKE SHE was run on a grid comprising of 120m square cells, for a pre-woodland period from 2001 to 2010. Sulphate was used as an indicator of the contaminant plume concentrations and transport across the study area. Six future woodland planting scenarios (2025 to 2034) were then simulated to determine the effects of mature Searsia lancea, Eucalyptus dunnii and Tamarix usneoides, and different planting scenarios on the contaminant plume. Results indicated that planting these deep-rooted species will be effective in decreasing the groundwater levels, groundwater flux and the quantity of contaminants reaching the river. Before tree water and contaminant uptake can be further modelled with improved accuracy within MIKE SHE, the limitations of the use of only one contaminant uptake value for the vegetation needs to be overcome, so that different uptake rates among different tree species can be shown.

This thesis describes methods for applying secondary water effects as spray, foam, splashes and mist to a fluid simulation system. For an art direction control over the base fluid flow a Fluid Implicit Particle solver with custom fields is also presented. The methods build upon production techniques within the visual effects industry, fluid dynamics and relevant computer graphics research. The implementation of the methods is created within Side Effects Software Houdini.

La valorisation de la biomasse en molécules plateformes, telles que les oléfines pour l'industrie des polymères, rend nécessaire l'adaptation des catalyseurs utilisés en pétrochimie à la transformation de composés fortement hydratés. Ces travaux de thèse ont permis de développer une méthode de caractérisation complète des catalyseurs acides en présence d'eau et en conditions réactionnelles. Cette méthode combine un examen des propriétés catalytiques en étudiant l'effet de l'eau sur des paramètres tels que le temps de contact, la température ou le vieillissement du catalyseur, mais aussi des propriétés physico-chimiques en étudiant la structure et la texture des catalyseurs usés et une études des sites acides en présence d'eau et en température. L'évolution de sites acides a été mesurée par FTIR in situ sous flux continu de NH3 et H2O. Les éventuelles compétitions d'adsorption entre H2O et NH3 mais aussi entre H2O et le réactif ont été estimées par la mesure des chaleurs d'adsorptions de ces espèces. Des oxydes d'intérêt (SnO2/SiO2, WO3/SiO2, TiO2/SiO2 et H4SiW12O40/SiO2) ont été synthétisés. Ces oxydes ont été caractérisés finement, notamment au niveau de leur acidité (utilisation de quatre molécules sondes différentes) / The use of biomass to obtain platforms molecules such as olefins for the polymer industry, require an adaptation of the catalysts already used in petrochemical processing for the conversion of highly hydrated compounds. During this project we developed a method for acid catalysts characterization in the presence of water and in reaction conditions. This method combines an analysis of catalytic properties by studying the effect of water on parameters such as contact time, temperature, or aging of the catalyst, but also of physicochemical properties in studying the structure and texture of spent catalysts and a study of the acid sites in the presence of water and temperature. The acid sites evolution of was measured by FTIR in situ under continuous flow of NH3 and H2O. The possible competition of adsorption between H2O and NH3 but also between H2O and the reactant were estimated by measuring the heat of adsorption of these species. Oxides of interest (SnO2 / SiO2, WO3/SiO2, TiO2/SiO2 and H4SiW12O40 / SiO 2) were synthesized. These oxides have been finely characterized, particularly in terms of their acidity (using four different probes molecules)

A vessel operating in the real world has to overcome wind, waves and ocean currents. The result of all the above is a motion of 6 degrees of freedom (DOF). Typically, for the maneuvering phase, the Newton-Euler equations are used to derive the equation of motion of the rigid body and the maneuvering theory to model the external forces and moments acting on a vessel. The main topic in this Master Thesis is to assess the maneuvering behavior of a specific container vessel through a 4DOF model. The purpose behind this study is to investigate the differences between the expected maneuvering behavior of the vessel and the operational one. To accomplish that, raw data from the vessel’s sea trials were used and a time domain simulation model created with the sway-roll yaw movements coupled and surge decoupled. The Son and No moto maneuvering model served as the base for the motion equations. The maneuvering coefficients (MC) were firstly estimated by semi-empirical formulas using the vessel particulars. The model was validated using the Esso Osaka sea trials data. The validation was limited to maneuvering parameters such as advance, tactical diameter, yaw overshoot angle etc. The final model was used on the sea trials data of the container vessel taking into consideration the wind forces through the Blender mann wind model. Moreover, correction factors for swallow water effects were used on the MC in order to provide a better accuracy and also to allow comparison between the operational data and the simulated ones since the sea trials depth could not be considered as deep waters. Finally, a system identification procedure was perfomed in order to investigate the possibility of identifying the exact MC values of a vessel. The results were encouraging. The simulation follows the patterns of the raw data relative accurately. In addition, the swallow water corrections provided enough evidence of the different behavior of the vessel depending on the depth under keel. From the SI side, a list of issues were encountered like parameter drift, multicollinearity and cost function prone to local minimum. A series of different procedures and algorithm proposed to overcome those difficulties and the results were promising.