A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 1990 / This work was carried out in response to the need for a simple engineering method for the thermal analysis of direct-contact air-water heat exchangers. A simple method of performance analysis is developed which is directly analogous and consistent with the fundamental approach used in conventional heat exchanger analysis and one in which the algebraic form of the overall equation and the grouping of each of the parameters are apparent. The range of conditions considered are air and water temperatures of between 0 and 50 DC and barometric pressures ranging from 80 to 120 kPa. The air conditions considered range from completely dry to completely satucated with water vapour. Both air cooling and water cooling processes are considered. [Abbreviated abstract. Open document to view full version]

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The major problem addressed by this study was to investigate the relationship between characteristics of the research methods used in selected subject subfields and the growth of published research in those subfields.

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An ongoing conversation in the Information Systems literature addresses the concern, "How can we conduct research that makes a difference?" A shortage of high-impact research will, over time, challenge the identity and weaken the viability of IS as an academic discipline. This paper presents the systematic high-impact research model (SHIR), an approach to conducting high-impact research. SHIR embodies the insight gained from three streams of high-impact research programs spanning more than 50 years. The SHIR framework rests on the proposition that IS researchers can produce higher-impact contributions by developing long-term research programs around major real-world issues, as opposed to ad hoc projects addressing a small piece of a large problem. These persistent research programs focus on addressing the entirety of an issue, by leveraging multidisciplinary, multiuniversity research centers that employ a breadth of research methods and large-scale projects. To function effectively, SHIR programs must be sustained by academic and practitioner partnerships, research centers, and outreach activities. We argue that SHIR research programs increase the likelihood of high impact research.

Steven Michael Ford, do hereby declare that this thesis is my own unaided work. This thesis has not been submitted in part or in full at this or any other university. This report is submitted in fulfilment of the degree of Master of Science in Engineering at the University of the Witwatersrand. / Aluminium, although often possessing adequate strength and toughness for a specific application, may be deemed unsuitable due to a less than satisfactory corrosion resistance. This unacceptable behaviour is especially prominent in the local mining industry where aluminium alloys corrode severely in the high chloride and sulphate containing waters. Of notable importance and the major motivating force for this research was the historically poor perfomance of aluminium alloy mine cages, which are suited to the task excepting for their unsatisfactory corrosion resistance. Of general importance however, is that the mining sector in South Africa represents a sizeable portion of the economy and could thus become a much greater consumer of aluminium if the metal's corrosion resistance could be improving Apart from varying the composition of the alloy, the other basic technique of increasing a metal's resistance to an environment is by applying a coating of some sort. This research looks into the use of aluminium-based metal sprayed coatings as a form of protection for various aluminium and steel substrate alloys. The purpose of a metal sprayed layer is not merely to isolate the substrate from the environment, hut also to act as a sacrificial anode at regions where the substrate is exposed. Previous work suggested that alloys of aluminium/zinc/indium produced excellent sacrificial anodes and were thus selected for this research. The zinc and indium were always alloyed with pure aluminium, with the percentage zinc varying between 0 and 12%. All the coating alloys were sprayed on a AA6261 and AA5083 aluminium alloys, a metal matrix composite and a mild steel alloy, Various electrochemical and immersion trials were then carried out in several synthetic mine waters and other corrosive media. The basic conclusion to be drawn from the results achieved is that the optimum coating for a particular substrate alloy is the one that provides the greatest potential difference between it and the substrate, while still lasting the required lifetime of the component. The reason for this is that the greater the potential difference, the better the sacrificial protection and hence the better the protection offered to any exposed areas on the surface. The fact that the coating corrodes away with time means that a balance must be found between sacrificial behaviour and required lifetime. / Andrew Chakane 2018