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Landsystem analysis is a commonly applied methodology which focuses on process-form relationships when applied in glacial environments. It can be used to understand and recreate the geomorphological evolution of glacial deposits from modern and ancient sediments. The purpose of this study is to examine the forefields of three closely located outlet glaciers of the Vatnajökull Ice Cap in southeast Iceland to determine the factors affecting the landsystems of these glaciers. A combination of digital based methods and field work focusing on geomorphology and sedimentology were used to define the landsystems. A classification code and associated symbology was used in this study to create consistency of landsystem analysis and can be used in future similar studies of glacial environments. The three glaciers, Morsárjökull, Skaftafellsjökull and Svínafellsjökull were chosen due to their shared source and close proximity, lying within adjacent valleys. The historical changes of the three glaciers have been well documented with aerial photographs, historical maps and glacier margin measurements. LiDAR were used to interpolate 2 m digital elevation models (DEM) of the three glacier forefields. These glaciers have varying topography, bedrock type and ice distribution (hypsometry, equilibrium line altitude (ELA)) which impacts the deposition at the glacier margin. The forefields of Morsárjökull and Skaftafellsjökull exhibit many similarities in the distribution and scale of landforms similar to the characteristics of the established active temperate landsystem commonly found in Iceland. However, the forefield of Svínafellsjökull has many differences compared to Skaftafellsjökull and Morsárjökull in the scale, type and distribution of landforms and sediments. Bedrock type, hypsometry and glacial debris content are major factors that influence differences in these landsystems. These three forefields may be used as analogues to enhance understanding of paleoenvironmental conditions that existed along the southern margin of Pleistocene glaciers that covered much of northern North America and Europe in the past. / Thesis / Master of Science (MSc)

Cette thèse traite de l'analyse de nuages de points 3D désorganisé et s'appuie sur deux outils : un algorithme de partitionnement efficace inspiré des C-moyennes floues d'une part, et des outils de filtrage morphologique de représentation à base de triangulation de Delaunay d'autre part. Le cadre applicatif essentiel est la navigation autonome en robotique mobile en environnement inconnu, c'est-à-dire dans modèle. Mais la méthodologie générique développée a été appliquée à d'autres types d'environnements, notamment plus structurés.

Fluorescence techniques are being considered for the detection and identification of bacterial spores. This thesis sets out to empirically characterize the detailed autofluorescence spectroscopic properties of spores and their target molecules. The multiwavelength fluorescence studies from a unique endogenous biomarker, dipicolinic acid (DPA) and its calcium salt (CaDPA) in bacterial spores are found to be useful for fluorescence characterization of spores. A systematic determination of the fluorescence profile of the major chemical components of Bacillus spores and the effect of UV irradiation on them has been performed in dry samples, wet paste and in aqueous solution. The thesis applies reliable tools for accurately describing complex nature of spectral profile from bacterial spores, and for interpreting and identifying their spectral properties. We show that multiwavelength fluorescence technique combined with Principal Component Analysis (PCA) clearly indicates identifiable grouping among dry and wet Bacillus spore species. Differences are also observed between dried, wet and redried spores, indicating the stark effect of hydration on fluorescence fingerprints. The study revealed that changes in fluorescence of spores due to hydration/drying were reversible and supports a recent model of a dynamic and dormant spore structure. The spectra were analysed with PCA, revealing several spectroscopically characteristic features enabling spore species separation. The identified spectral features could be attributed to specific spore chemical components by comparing the spore sample signals with spectra obtained from the target molecules. PCA indicated underlying spectral patterns strongly related to species and the derived components were correlated with the chemical composition of the spore samples. More importantly, we examined and compared the fluorescence of normal spores with a mutant of the same strain whose spores lack DPA. We discovered that the dramatic fluorescence enhancement of Bacillus spores can be caused by UV irradiation in the spectral region of this unique biomarker without any pre treatment. Differences between spectra of spores, spore strains and other biological samples are very marked and are due to the dominance of the dipicolinate features in the spore spectra. This could lead to a cheap, more sensitive, faster and reagentless bacterial spore detector.

Microtruss materials are assemblies of struts or columns arranged periodically in space. The majority of past research efforts have focused on the key issue of microtruss architectural optimization. By contrast, this study focuses on the internal material structure at the level of the individual struts. Microstructural, geometrical, and material design techniques are used to improve their mechanical properties. The finite element method is used to verify and create predictive analytical models, explain the dependence of strut properties on geometry, material properties and failure mechanisms, and extend the strut design analysis into suggestions for the improvement of fabrication methods. Three strut design methods are considered. First, microstructural design is performed by considering the influence of strut geometry on the strain energy imparted during stretch bending. By using the perforation geometry to modify the location and magnitude of this strain energy, microtruss materials with lower density and higher strength can be fabricated. Second, structural sleeves of aluminum oxide and electrodeposited nanocrystalline nickel are used to reinforce architecturally optimized aluminum alloy microtruss assemblies, creating hybrid materials with high weight-specific strength. The mechanical properties are controlled by the interaction between material and mechanical failure; this interaction is studied through finite element analyses and a proposed analytical relationship to provide suggestions for further improvements. Finally, hollow cylindrical struts are fabricated from electrodeposited nanocrystalline nickel. The high strength to weight ratio achieved in these struts is due to the microstructural and cross-sectional efficiency of the material.

Microtruss materials are assemblies of struts or columns arranged periodically in space. The majority of past research efforts have focused on the key issue of microtruss architectural optimization. By contrast, this study focuses on the internal material structure at the level of the individual struts. Microstructural, geometrical, and material design techniques are used to improve their mechanical properties. The finite element method is used to verify and create predictive analytical models, explain the dependence of strut properties on geometry, material properties and failure mechanisms, and extend the strut design analysis into suggestions for the improvement of fabrication methods. Three strut design methods are considered. First, microstructural design is performed by considering the influence of strut geometry on the strain energy imparted during stretch bending. By using the perforation geometry to modify the location and magnitude of this strain energy, microtruss materials with lower density and higher strength can be fabricated. Second, structural sleeves of aluminum oxide and electrodeposited nanocrystalline nickel are used to reinforce architecturally optimized aluminum alloy microtruss assemblies, creating hybrid materials with high weight-specific strength. The mechanical properties are controlled by the interaction between material and mechanical failure; this interaction is studied through finite element analyses and a proposed analytical relationship to provide suggestions for further improvements. Finally, hollow cylindrical struts are fabricated from electrodeposited nanocrystalline nickel. The high strength to weight ratio achieved in these struts is due to the microstructural and cross-sectional efficiency of the material.

Fluorescence techniques are being considered for the detection and identification of bacterial spores. This thesis sets out to empirically characterize the detailed autofluorescence spectroscopic properties of spores and their target molecules. The multiwavelength fluorescence studies from a unique endogenous biomarker, dipicolinic acid (DPA) and its calcium salt (CaDPA) in bacterial spores are found to be useful for fluorescence characterization of spores. A systematic determination of the fluorescence profile of the major chemical components of Bacillus spores and the effect of UV irradiation on them has been performed in dry samples, wet paste and in aqueous solution. The thesis applies reliable tools for accurately describing complex nature of spectral profile from bacterial spores, and for interpreting and identifying their spectral properties. We show that multiwavelength fluorescence technique combined with Principal Component Analysis (PCA) clearly indicates identifiable grouping among dry and wet Bacillus spore species. Differences are also observed between dried, wet and redried spores, indicating the stark effect of hydration on fluorescence fingerprints. The study revealed that changes in fluorescence of spores due to hydration/drying were reversible and supports a recent model of a dynamic and dormant spore structure. The spectra were analysed with PCA, revealing several spectroscopically characteristic features enabling spore species separation. The identified spectral features could be attributed to specific spore chemical components by comparing the spore sample signals with spectra obtained from the target molecules. PCA indicated underlying spectral patterns strongly related to species and the derived components were correlated with the chemical composition of the spore samples. More importantly, we examined and compared the fluorescence of normal spores with a mutant of the same strain whose spores lack DPA. We discovered that the dramatic fluorescence enhancement of Bacillus spores can be caused by UV irradiation in the spectral region of this unique biomarker without any pre treatment. Differences between spectra of spores, spore strains and other biological samples are very marked and are due to the dominance of the dipicolinate features in the spore spectra. This could lead to a cheap, more sensitive, faster and reagentless bacterial spore detector.

Autogenous (AG) milling is utilised around the world for rst stage particle size reduction. The system exhibits highly non-linear behaviour in addition to being subject to unmeasured variability associated with most ore bodies. Anglo American Platinum aimed at improving online optimisation of the circuit by implementing industrial model predictive control to reduce system variability and continuously drive towards the optimal operating point within system constraints. A dimensional analysis of the circuit was conducted to explain the relationships between the various milling parameters discussed in the literature survey. The measured variables used in the analysis satis ed Buckingham's theorem, indicating that a complete subset of dimensionless groups were present and suitably able to describe process movement. These relationships were used as a reference point in determining the dynamic step response models between these variables necessary for model based control. The industrial dynamic matrix controller commissioned on the AG mill resulted in a 66 % reduction in power and a 40 % reduction in load. These are the main controlled variables of the mill. The controller also managed to reduce its objective function, e ective power utilisation, by 11 %. This stability improvement enabled a test campaign where the mill was controlled at various operating regions in order to establish the conditions conducive to the nest product size at a given mill feed rate. Moving the mill's operating region from the benchmarked plant to this optimal grind environment (at benchmarked variability) provided an estimated potential recovery increase of 0.27 % (absolute) due to better precious metal liberation. Stabilising the mill at this point with the model predictive controller resulted in a further 0.04 % potential recovery increase (absolute). The 0.31 % potential recovery increase is estimated at a monetary value of $93.1 million per annum. Copyright / Dissertation (MEng)--University of Pretoria, 2013. / Chemical Engineering / unrestricted

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