Bibliography: leaves 101-107. / Previous experience with the preparation and testing of Co/alumina catalysts for Fischer-Tropsch synthesis has revealed that, while commercial available aluminas result in materials of significantly different catalytic performance, no correlation between the physical properties of the aluminas and the resulting catalytic performance was evident. Consequently, it was proposed that differences in the chemical (acid/base) nature of the alumina surfaces might be responsible for the observed differences in catalytic behaviour. In this study, isopropanol conversion was evaluated as a possible test reaction for characterisation of the acid/base nature of commercial aluminas - literature indicates acetone to result from isopropanol reaction on basic sites, and DIPE and propene products to result from isopropanol conversion over acid sites of varying strength.

Includes bibliographical references. / This thesis describes the Gollach cluster. The Gollach is an eight machine computing cluster that is aimed at being a general purpose computing resource for research purposes. This includes image processing and simulations. The main quest in this project is to create a cluster server that gives increased computational power and a unified system image (at several levels) without requiring the users to learn specialised tricks. At the same time the cluster must not be tasking to administer.

Bibliography: leaves 66-68. / This dissertation aims to establish the possibilities of mapping wetlands in Qoqodala, Eastern Cape Province, South Africa, using Landsat and/or Aster imagery. The methodology for mapping wetlands using Landsat imagery, proposed by Thompson, Marneweck, Bell, Kotze, Muller, Cox and Smith (2002) is adapted and applied to the study area. The same methodology is modified for use with Aster imagery and applied to the study area. In addition, the possibilities of treating Aster as a hyperspectral image are investigated, and a methodology using hyperspectral processing techniques is implemented.

South African synthetic fuel plants produce large quantities of lower alkenes which can be catalytically oligomerized to liquid transportation fuels. In the screening of experimental catalysts for the production of diesel-range fuels, it is important to measure the quality, as well as the quantity, of the fuel being produced. Cetane number is an important indicator of the quality of a diesel fuel ru1d is measured by a standard engine test (ASTM D 613) which requires l litre of fuel and is therefore not suitable for the routine testing of the small volumes of fuel produced by experimental catalysts. Alternative cetane number prediction methods exist but these have generally been developed to predict the cetane number of crude-oil based fuels and are therefore not suitable for use with synthetically derived fuels. This thesis details the development of a formula which accurately predicts the cetane number of a fuel from other, easily measured parameters. Several samples of fuel were produced under varying reaction conditions and were hydrogenated to ensure that they were virtually 100% alkane. Differences in cetane number should therefore be due to differences in the degree of branching. By measuring the cetane number on a. standard test engine and correlating the result with the amount of branching as measured by ¹Hnmr, a formula was developed which was found to accurately predict the cetane number of these types of synthetic fuels. The results obtained also show that for the conversion of ethene over a supported nickel catalyst, cetane number decreases as temperature increases. This decrease is probably caused by secondary butane oligomerization reactions.

Bibliography: leaves 139-146. / This dissertation deals with the energy transition process which is de-fined herein as the process whereby energy consumption patterns o-f fuels used by a population change over time. The focus is on the domestic sector only and specific attention is paid to the black population o-f South Africa which is urbanizing rapidly. The existing data on -fourteen Sub-Saharan African countries are analysed and indications that the energy transition process is occurring are found. The process is influenced by both the level o-f urbanization and economic development but the rates o-f growth of these indicators do not appear to be influential.

Bibliography: leaves [141]-145. / This study has aimed to contribute to the development of low-cost or "simple" biogas technology, i.e. the design, construction, operation and utilisation of relatively simple biogas systems in South Africa, and to explore the utilisation of the technology by lower-income groups in the rural areas of the country, particularly in the former homelands. Specific objectives included the development of biogas plants suitable for application in South Africa, and the assessment of the acceptability of the technology among potential users. Five biogas plants were constructed during the study, which provided the opportunity to test various designs and obtain response from some of the potential users of the technology.

Includes bibliography. / Filamentous bulking, caused predominantly by low F/M filaments (Blackbeard et al, 1986, 1988), results in considerable settling problems in full scale nitrogen (N) and nutrient (N & P) removal activated sludge plants in South Africa. The development of specific methods for control of low F/M filaments in these plants would lead to significant savings because higher flows and loads could be treated in existing plants. From the findings of Blackbeard et al (1986, 1988) an extensive research project was undertaken by Gabb et al (1989a) into specific control of low F/M filament bulking. This project investigated the effectiveness of selectors, the proposed method of low F/M filamentous bulking control and found them to be ineffective. Consequently a second comprehensive laboratory research investigation was commenced in 1989. The work presented in this thesis forms a part of this investigation; the experimental investigation was conducted in 3 phases investigating (1) the effect of fully anoxic conditions and low nitrate concentrations during the anoxic phase of an intermittent aeration cycle on low F/M filament growth in continuously fed completely mixed single reactor systems receiving a synthetic sewage feed; (2) the effect of fully anoxic conditions on low F/M filament growth in continuously fed completely mixed single reactor systems receiving real sewage; and (3) the effect of alternating the frequency of exposure of low F/M filaments to anoxic/aerobic conditions (i.e. increasing the length of the aeration cycle but maintaining the aerobic mass fraction) in intermittently aerated continuously fed single completely mixed reactor systems receiving real sewage.

Bibliography : leaves I-VII. / The central problem on which this Masters research project builds is the perceived limited ability of small and medium-sized enterprises (SMEs) in the South African manufacturing sector to improve their environmental performance on their own. Waste minimisation is a valid and proven tool for the identification of ways to reduce or eliminate wastes.

Includes abstract. / Includes bibliographical references (leaves 96-101). / This thesis investigates the effect of ore blends on milling and flotation performance. Anglo Platinum's Waterval UG2 concentrator in Rustenburg processes ore from various shafts.

Includes bibliographical references (p. 71-75). / Ultra-wideband (UWB) technology can be used in many applications, including radar, communications, and geo-location. In this dissertation, UWB technology is utilized to directly generate sub-nanosecond pulses with more than 1 GHz bandwidth to implement radio detection and ranging (RADAR) for distances up to 5 or 10 metres. This low-cost, rnicropower radiation, short-range radar profiling system consists of the radar circuitry, the data-acquisition subsystem, the signal processing subsystem and the graphical user interface. Additional modules such as a front-end RF amplifier can be integrated into the complete system. The performance was analysed, particularly the circuitry performance and system performance. The capability for detecting metal objects was demonstrated, along with discussion of preliminary "seeing-through-wall" experiments.