Includes abstract. / This dissertation describes the examination of a SAR transceiver, as a prototype L band sensor, to be used in a software defined radar system. This examination includes the evaluation, testing and recommissioning the available hardware. Tests on various subsystems which make up the sensor are carried out and described in detail.

Includes synopsis. / Includes bibliographical references. / In the current study, the successful development of a novel in-situ X-ray diffraction cell is described. This cell allows the direct observation of crystallite changes to be made under reaction conditions and in real time. The cell permits operation up to 500°C and 25 bar to be realised, with more severe conditions being achievable upon changing the reactor component. The design is such that it can be mounted to any commercial, laboratory-scale X-ray diffractometer or synchrotron facility.

Includes abstract. / Includes bibliographical references (leaves 143-152). / As-built models of industrial piping installations are essential for planning applications in industry. Laser scanning has emerged as the preferred data acquisition method of as built information for creating these three dimensional (3D) models. The product of the scanning process is a cloud of points representing scanned surfaces. From this point cloud, 3D models of the surfaces are reconstructed. Most surfaces are of piping elements e.g. straight pipes, t-junctions, elbows, spheres. The automatic detection of these piping elements in point clouds has the greatest impact on the reconstructed model. Various algorithms have been proposed for detecting piping elements in point clouds. However, most algorithms detect cylinders (straight pipes) and planes which make up a small percentage of piping elements found in industrial installations. In addition, these algorithms do not allow for deformation detection in pipes. Therefore, the work in this research is aimed at the detection of piping elements (straight pipes, elbows, t-junctions and flange) in point clouds including deformation detection.

Includes abstract. / Includes bibliographical references. / The corrosion of sewer pipe concrete is a global problem, especially in warm climates in which biogenically generated sulphuric acid attacks the concrete and lowers its structural integrity. The Virginia Experimental Sewer is a ‘live sewer’ in South Africa for investigating acid resistance of concrete made with different cement/aggregate combinations...

abstract: The intrinsic material properties of diamond are attractive for use in high power limiter/receiver protector (RP) systems, especially the ones required at the input of radio transceivers. The RP device presents a low capacitance and high resistance to low input signals, thereby adding negligible insertion loss to these desired signals. However, at high input radio frequency (RF) power levels, the RP turns on with a resistance much smaller than the 50 Ω characteristic impedance, reflecting most of the potentially damaging input power away from the receiver input. P-type-intrinsic-n-type (PIN) diodes made of Silicon and Gallium Arsenide used in today’s conventional RP systems have certain limitations at high-power. The wide bandgap of diamond combined with its higher thermal conductivity give it a superior RF power handling capability that can protect sensitive RF front-end components from high power incident signals. Vertical diamond PIN diodes were proposed and fabricated with an n+-i-p++ structure consisting of: a very thin and heavily phosphorus-doped n-type diamond layer and an intrinsic diamond layer grown on a heavily boron-doped diamond substrate with a (111) crystallographic orientation. Direct current (DC) and RF small-signal characterization was carried out by attaching the diamond sample in a shunted coplanar waveguide (CPW) configuration. The small-signal lumped element model of the diode impedance under forward-bias was validated with a fit to the measured data, and provides a roadmap for the optimization of parameters for the implementation of diamond Schottky PIN diodes to be successfully used in receiver protector/limiter applications at S-band. The experimental results with the device growth and fabrication show promise and can help in further elevating the device RF figure of merit, in turn enabling the path for commercialization of these diamond-based devices. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2020

abstract: Analytics are being collected on a day to day basis on just about anything that you can think of. Sports is one of the recent fields that has started implementing the tool into their game. Analytics can be described as an abundance of statistical information that show situational tendencies of other teams and players. It is hypothesized that analytics provide anticipatory information that allows athletes to know what is coming; therefore, allowing them to perform better in real game scenarios. However, it is unclear how this information should be presented to athletes and whether athletes can actually retain the abundance of information given to them. Two different types of presentation methods (Numeric and Numeric plus Graph) and two different amounts of analytic information (High and Low) were compared for baseball players in an online based baseball specific retention survey: High Numeric (excess information shown in spreadsheet format), Low Numeric (key information shown in spreadsheet format), High Numeric plus Graph (excess information shown as a spreadsheet with hitting zone maps), and Low Numeric plus Graph (key information shown as a spreadsheet with hitting zone maps). Athletes produced different retention scores for the type of presentation method given across the whole study. Athletes presented analytic as Numeric plus Graph performed better than athletes in just Numeric condition. Additionally, playing experience had a significant effect on an athlete’s ability to retain analytic information. Athletes with 10 plus years of baseball experience performed better in every condition other than High Numeric plus Graph compared to athletes with less than 10 years of experience. Amount and experience also had an interaction effect that produced statistical significance; those with less experience performed better in conditions with less baseball information given whereas those with more experience were able to handle more baseball information at once. Providing analytic information gives athletes, especially baseball batters, a significant advantage over their opponent; however, ability to retain analytic information depends on how the information is presented and to whom the information is being presented. / Dissertation/Thesis / Analytic Survey / Masters Thesis Human Systems Engineering 2020

Heap Leaching has gained much relevance in the processing of low-grade mineral resources - ores considered uneconomical for beneficiation through conventional concentration and tank leaching. However, it is at the same time characterized by extended leaching periods due to slow mineral conversion and low rates of recovery as a major challenge. Interactions within the heap bed are not fully understood as chemical leaching and hydrodynamics interact in a complex manner. To study these interactions, a number of investigations have focused on the hydrodynamic interaction using conventional residence time distribution (RTD) studies in laboratory columns. In these RTD studies, the flows of tracer exiting through the effluent stream provide information of its paths, where some flows might relate to fast movement, slow convoluted channels, or micro/macro stagnated regions. This information is usually interpreted through simplified reactor models representing the bed as a combination of plug flow reactors (PFRs), continuous stirred tank reactors (CSTRs) and dead zones. Using columns as reactors to approximate heap leaching on a laboratory scale, it is anticipated that the RTD flow distribution response should be similar to the distribution of a PFR with associated dead zones. While some literature sources have alluded to the response in columns being similar to a plug flow response, recent sources using a similar hydrodynamic RTD approach reported column reactor distribution resembling flow more typical of a continuous stirred tank, CSTR, system instead of plug flow. Given that packed ore beds are not agitated, this appears paradoxical. It is hypothesised that the CSTR-like response is a result of the distribution of convoluted flow channels through the ore bed, which perform overall like a bundle of PFRs of different lengths. To discern the two patterns the use of a reactive leaching on a well characterized ore material is proposed. Therefore, this work aims to study simultaneously the flow and leach performance of a laboratory column reactor, utilizing a novel reactive leaching approach with a lixiviant amendable to a well-characterized homogeneous solid material. The objective of this work is to establish flow distribution performance in packed bed columns and correlate such performance to the ultimate extraction from the packed bed. The study was performed using a nonreactive solution tracer (potassium nitrate) to characterise flow through a column packed with an artificial silver ‘ore' (silver grains embedded in concrete), followed by a reactive leaching study using sodium cyanide which would leach the silver. The artificial silver ore was developed with the aim to exhibit four ideal properties, namely homogeneous porosity, uniform grain size, homogenous dispersion of the grains throughout the ore, and even grade distribution of the different size fractions after crushing. Leaching and micro-XCT characterization studies were performed in order to determine the leaching properties of the artificial silver ore and validate the ore corresponds to these ideal properties. This validation was indeed achieved; however, the inner-particle pores were not found to be continuous at the scale of resolution of the instrument (4.8 microns). Poor extraction from the coarse particles in both the leaching characterization and reactive column leaching investigations suggested that this network was not well established and may exist only at the sub-micron scale. Leach tests were performed on individual particle sizes in both shake flask and circulating bed reactor tests. Extraction from the leaching of the coarse synthetic silver ore particles was observed to be very low relative to dissolution from pure silver metal grains. Diagnostic shrinking core and the extended mixed topology models were used to determine the controlling dissolution mechanism. Both models demonstrated that a diffusion-reaction mechanism governed the dissolution extraction from the large particles. RTD column leaching studies were performed utilizing flow rate and PSD as investigated parameters. The nonreactive tracer produced a step-change flow response that was more similar to a characteristic plug flow type distribution but showed distinct deviations towards CSTR behavior, especially for the beds containing a higher degree of fines. Reactive column leaching experiments were performed under similar conditions as the nonreactive RTD, introducing a step-change of the cyanide reagent. Rapid silver leaching occurred initially, but equally rapidly declined to very low rates. The leach curves were interpreted by translating the information obtained from the nonreactive RTDs into a distribution of parallel plug flow channels. The extent of reaction for each of these channels is derived from the surface reaction model for the individual size classes, put together for the corresponding PSD in each experiment. RTD specific PSDs tested using this approach assumed that longer residence times correspond to the prevalence of finer material. The validity of the approach was tested by comparing the extraction determined from the particle leaching kinetics studies to the reactive column data through modelling. The model is based on the weighted average leaching from a population of particles, calibrated against kinetic models formulated for individual size classes. This model is further linked to a distribution of flow channels determined from the RTD studies. The prediction of the model did not compare too well against the raw silver dissolution data of the columns. This was attributed to the model having been calibrated against kinetic data that did not fully consider the smaller size classes below -4/+2.8 mm – considered to be the key source of rapid surface reaction in the packed bed. Although the concept proposed in this project was not fully proven, further test work is recommended to expand on the approach presented here.

Water is a basic need and a limited resource across the world. Climate change, pollution, population growth, irrigation and urban development, among others, contribute to the issues faced with respect to availability of quality of water resources and security of water supply for consumption. Pressure management, is the most common and feasible demand management initiative implemented by the City of Cape Town Metro. The main focus of these initiatives is to reduce water losses within the water distribution system. Influence of pressure on water consumption is also observed, but has not been as well investigated as with leakage-pressure relationships. This study aims to assess the impact of change in system pressure on consumer water demand. To do this a pressure managed DMA and Control DMA was identified. The billed consumption data was analysed for 11 months before and 11 months after the pressure management period. A control DMA served to verify that the consumption reduction was as a result of pressure management and not any other intervention. Furthermore, this study involved the collection and analyses of the logged system flow data prior to and post commissioning of pressure management. Pressure is not fixed and varies overtime. The Average Zone Pressure was not available from logged data and was calculated by simulating the hydraulic model to reflect the system conditions prior and post commissioning of the pressure managed DMA. Following that, an investigation into how the leakage responds to pressure was performed. Since the latter affects the demand response to pressure. It was then decided to separate the leakage from consumption. In order to do this, various leakage parameters were calculated and randomly distributed across the system. To analyse the leakage before and after pressure management, two types of models were used, namely 1) Epanet Model (based on the Orifice Equation) and 2) the Epaleaks Model (based on the Modified Orifice Equation). N3 is the coefficient of elasticity. This coefficient represents the relationship between pressure and flow rate. Normal N3 analysis was performed on the available data. N3 was calculated for the system consumption, based on the logged data and a sample of the billed consumption records. The power regression model suggests an N3 of approximately 0.05 to 0.06 for the system based on a sample of filtered billed consumption data. However, in the case of the entire system's end use consumption the N3 value is approximately 0.4. Overall, the N3 values compared reasonably well with other studies in the range of 0.04 to 0.29 and in some cases ≈0.5.

abstract: A framework to obtain the failure surface of a unidirectional composite which can be used as an input for Generalized Tabulated Failure Criterion in MAT_213 – an orthotropic elasto-plastic material model implemented in LS-DYNA, a commercial finite element program, is discussed in this research. A finite element model consisting of the fiber and the matrix is generated using the Virtual Testing Software System (VTSS) developed at Arizona State University (ASU). The framework is illustrated using the T800-F3900 unidirectional composite material manufactured by Toray Composites. The T800S fiber is modeled using MAT_213. The F3900 matrix phase is modeled using MAT_187-SAMP1. The response of the virtual tests in 1-direction tension, 1-direction compression, 2-direction tension, 2-direction compression and 2-1 plane shear are verified against the results obtained from experiments performed under quasi-static and room temperature conditions (QS-RT). Finally, a roadmap to generate the failure surface using virtual test is proposed. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2020

Includes bibliographical references (leaves 155-162). / Technology is the driving force behind much of the change taking place in the world today. Consequently, across society, calls are being made to ensure technological literacy is a meaningful and central part of schooling to adequately prepare pupils to become part of an increasingly technologically driven world. However, studies have shown that large parts of society perceive technology primarily in terms of computers.