Continuous improvements to industrial equipment used in essential industrial applications are a key for the commercial success to the equipment manufacturers. Industrial applications always demand optimum performance and reliability and almost all equipment used in industrial applications is complex and are very expensive to replace. Often modifications to hardware and retrofitting additional hardware are encouraged by most equipment manufacturers and operators. The complexity of these systems however, makes assessment of modifications and design change difficult. This research implemented system modelling techniques to overcome this issue, by developing virtual test platforms of two distinctive industrial systems for enhancement assessment. The two distinctive systems were the electronic equipment called pulser-receiver used in ultrasonic non-destructive testing of safety critical oil & gas pipelines and a high voltage power supply used in high energy electron beam welding. Optimisation with emphasis on portability of the pulser-receiver and rapid weld recovery after a flashover fault condition in the electron beam welding application required assessment before design changes were made to hardware. SPICE based simulators LTSpice and PSpice were used to model and simulate the pulser-receiver and the welding power supply respectively. All the models were evaluated appropriately against theoretical data and published datasheets. However, validation of low level component models developed in the research against measurement data at a component level suffered due to system complexity and resource constraints. Close mapping of simulation results to measurement data at a system level were obtained. The research helped build up a wealth of knowledge in the development of circuit simulation models that can be analysed in the time domain with no non-convergent issues. Simulation settings were relaxed without compromising accuracy of model performance.

Since the dawn of democracy, South Africa has had ostensibly all of the essential elements that are assumed to be sufficient for a country to develop an active market for hostile takeovers, in other words dispersed shareholder ownership, depressed shareholding, and a United Kingdom- or United States-inspired regulatory framework. This has not gone unnoticed. But even with this essential element a wave of hostile takeovers has never hit South Africa. Renewed excitement surrounding hostile takeovers has been revived by the attempted takeover of Murray & Roberts by Aton. The conspiracy stalled when the bid was challenged by the independent board of directors of Murray & Roberts at the Takeover Regulation Panel (TRP) and opposed by the Competition Commission. It appears as if Murray & Roberts successfully defended the hostile takeover by Aton, thereby continuing the narrative that hostile takeovers seldom succeed in South Africa, which raises questions about the feasibility of hostile takeovers in South Africa. This is the enigma of hostile takeovers in South Africa which the study seeks to examine. The research argues that, by applying abstract theories derived from the Anglo- American experience, most outside observers have neglected to properly account for local, idiosyncratic, South African factors that have stifled the market for corporate control in South Africa. / Mini Dissertation (LLM) University of Pretoria, 2019. / Mercantile Law / LLM / Unrestricted

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I wanted to devote a year of my life toward creating a building and participating in a body of research that was meaningful. My goal proved to be much more complex than originally thought, for meaning itself is ambiguous. Although ambiguous, meaning is not without definition: it is bounded by the contingency of our "cogito" or horizons of experience. And so I argue that if we assign meaning through a function of self reflection, than perhaps a shared experience may transcend the self and reflect community. In an attempt to fertilize community through the built environment, I designed a Charter School on the abandoned 1400 block of Walnut Street in the Over-the-Rhine neighborhood of Cincinnati, Ohio. / Master of Architecture

La méiose est un processus fondamental qui conditionne la formation de gamètes et assure la stabilité des génomes tout en générant de la diversité par brassage génétique. La régularité méiotique nécessite la formation de crossing-overs (CO) exclusivement entre chromosomes homologues. Cette condition est plus difficile à remplir chez les espèces allopolyploïdes qui présentent plusieurs jeux de chromosomes toujours susceptibles de recombiner ensemble. Bien que la polyploïdie soit omniprésente chez les plantes, on connait peu de choses sur le déroulement de la méiose chez ces espèces. Au cours de ma thèse, je suis intéressée à l’effet de la polyploïdie sur la formation et sur la fréquence de CO en utilisant le colza (Brassica napus, AACC, 2n=38) comme modèle d’étude. J’ai notamment cherché à comprendre : (1) quel est l’effet du niveau de ploïdie sur la fréquence de crossovers, et (2) l’origine des variations de COs observées chez les plantes allohaploïdes (AC) produites à partir de différentes variétés de colza, en utilisant une palette d’approches cytologiques et cytogénétiques. Mes travaux ont permis de montrer que le niveau de ploïdie induit une augmentation de la fréquence de crossovers, et que cette augmentation est plus importante dans un contexte triploïde que tétraploïde. J’ai ainsi montré que la fréquence de CO augmente progressivement du diploïde (1,6 CO/bivalent) vers le tétraploïde (2 CO/bivalents) et quelle est maximale chez le triploïde (2,8 CO/bivalent). En ce qui concerne la deuxième question, j’ai montré que la différence entre les allohaploïdes de colzas apparaît tardivement au cours de la méiose. Elle semble être liée à une capacité différente à former des CO en fonction de la variété utilisée pour produire ces allohaploïdes et non pas à une différence dans la reconnaissance de l’homologie. Un de mes résultats original est que la protéine HEI10, impliquée dans la voie de formation des CO interférents, présente une dynamique différente entre les deux variétés, que ce soit à l’état euploïde (AACC) qu’allohaploïde (AC).Mes résultats conduisent à s’interroger sur la relation entre (i) la régulation du nombre de CO formés entre chromosomes homologues et (ii) la suppression des CO entre chromosomes non homologues chez les espèces allopolyploïdes. / Meiosis is a fundamental process required to produce gametes, ensure genome stability and generate diversity within species by creating new chromosome/allele combinations. For all these outcomes the exclusive formation of crossovers (CO) between homologous chromosomes is required. This condition is more difficult to fulfil in allopolyploid species that have more than two sets of chromosomes still able to recombine together. Although polyploidy has been particularly prevalent in plants, little is known about meiosis in polyploids. During my thesis I have analyzed the effect of polyploidy on CO formation and frequency, using oilseed rape (Brassica napus, AACC, 2n=38) as model. My work aimed to investigate (i) the effect of ploidy level on the rate of meiotic COs and (ii) the causes for the observed difference in CO rate between allohaploid plants (AC) produced from different B. napus varieties. To address these questions, I have combined a series of cytological, immunocytological and cytogenetical analyses.My work first indicates that polyploidization leads to increase CO frequency. I showed that the number of COs progressively increases from the diploid (1,6 CO/bivalent) to the tetraploid (2 CO/bivalent) and is maximal in the triploid (2,8 CO/bivalent). In the second part, I have shown that the difference of meiotic behaviors between B. napus allohaploids appears at a late stage of meiosis. This difference seems to be due to a difference in the propensity to form CO between the two varieties rather than a difference in the stringency of homology recognition. This difference could be related to the difference in the pattern and/or chronology of HEI10 (a key protein involved in the interfering CO pathway) signals along chromosomes during prophase I in both euploids (AACC) and allohaploids (AC).My results thus puts under the spotlight the link that may exist between (i) the regulation of CO rate between homologous chromosomes and (ii) the suppression of COs between non-homologous chromosomes in polyploid species.

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