Faculty of Engineering and the Built Environment (ETDs)

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A Data Science Framework for Mineral Resource Exploration and Estimation Using Remote Sensing and Machine Learning
(University of the Witwatersrand, Johannesburg, 2023-08) Muhammad Ahsan, Mahboob; Celik, Turgay; Genc, Bekir
Exploring mineral resources and transforming them into ore reserves is imperative for sustainable economic growth, particularly in low income developing economy countries. Limited exploration budgets, inaccessible areas, and long data processing times necessitate the use of advanced multidisciplinary technologies for minerals exploration and resource estimation. The conventional methods used for mineral resources exploration require expertise, understanding and knowledge of the spatial statistics, resource modelling, geology, mining engineering and clean validated data to build accurate estimations. In the past few years, data science has become increasingly important in the field of minerals exploration and estimation. This study is a step forward in this field of data science and its integration with minerals exploration and estimation. The research has been conducted to develop a state-of-the-art data science framework that can effectively use limited field data with remotely sensed satellite data for efficient mineral exploration and estimation, which was validated through case studies. Satellite remote sensing has emerged as a powerful modern technology for mineral resources exploration and estimation. This technology has been used to map and identify minerals, geological features, and lithology. Using digital image processing techniques (band ratios, spectral band combinations, spectral angle mapper and principal component analysis), the hydrothermal alteration of potential mineralization was mapped and analysed. Advanced machine learning and geostatistical models have been used to evaluate and predict the mineralization using field based geochemical samples, drillholes samples, and multispectral satellite remote sensing based hydrothermal alteration information. Several machine learning models were applied including the Convolutional Neural Networks (CNN), Random Forest (RF), Support Vector Machine (SVM), Support Vector Regression (SVR), Generalized Linear Model (GLM), and Decision Tree (DT). The geostatistical models used include the Inverse Distance Weighting (IDW) and Kriging with different semivariogram models. IDW was used to interpolate data points to make a prediction on mineralization, while Kriging used the spatial autocorrelation to make predictions. In order to assess the performance of machine learning and geostatistical models, a variety of predictive accuracy metrics such as confusion matrix, a receiver operating characteristic (ROC) curve, and a success-rate curve were used. In addition, Mean Absolute Error, Mean Square Error, and root mean square prediction error were also used. The results obtained based on the 10 m spatial resolution show that Zn is best predicted with RF with significant R2 values of 0.74 (p < 0.01) and 0.7 (p < 0.01) during training and testing. However, for Pb, the best prediction is made by SVR with significant R2 values of 0.72 (p < 0.01) and 0.64 (p < 0.01) for training and testing, respectively. Overall, the performance of SVR and RF outperforms the other machine learning models with the highest testing R2 values. The experimental results also showed that there is no single method that can be used independently to predict the spatial distribution of geochemical elements in streams. Instead, a combinatory approach of IDW and kriging is advised to generate more accurate predictions. For the case study of copper prediction, the results showed that the RF model exhibited the highest predictive accuracy, consistency and interpretability among the three ML models evaluated in this study. RF model also achieved the highest predictive efficiency in capturing known copper (Cu) deposits within a small prospective area. In comparison to the SVM and CNN models, the RF model outperformed them in terms of predictive accuracy and interpretability. The evaluation results have showed that the data science framework is able to deliver highly accurate results in minerals exploration and estimation. The results of the research were published through several peer reviewed journal and conference articles. The innovative aspect of the research is the use of machine learning models to both satellite remote sensing and field data, which allows for the identification of highly prospective mineral deposits. The framework developed in this study is cost-effective and time-saving and can be applied to inaccessible and/or new areas with limited ground-based knowledge to obtain reliable and up- to-date mineral information.
A model for integrated tourism infrastructure planning in the South African public sector
(2024) Chettiar, Shamilla
Infrastructure supports competitiveness, productivity and economic growth. While planning is critical for co-ordination and delivery of infrastructure, integrated infrastructure planning models remain elusive. Integrated infrastructure planning is especially important to derive maximum benefits from limited public sector funding. This research focussed on infrastructure planning in the tourism context. Within the complex South African public sector planning system, the responsibility for infrastructure and tourism planning lies with multiple departments at national, provincial and local government spheres. Tourism infrastructure needs can therefore best be addressed through integrated planning. This thesis presents the results of a qualitative, multi-method study. Various methods, such as reviews of documents, key-informant interviews, focus groups and case studies were utilised to gather data. The research also contains the reflections of the researcher who has extensive experience in public sector planning. The research question was: “What are the key elements of a model for integrated tourism infrastructure planning undertaken by the South African public sector?” The model proposes three key elements - a National Tourism Spatial Development Framework; Regional Tourism Masterplans; and a Tourism Infrastructure Strategy and Plan. A People component has also emerged as being significant for the effectiveness of the model. The study further confirmed that the model will support the integration of tourism, economic, spatial and infrastructure planning and development. In the long - term integrated public sector tourism infrastructure planning in South Africa, should yield greater public sector investment, stimulate greater private sector investment, and ultimately support the growth and competitiveness of the tourism sector. This research makes a significant contribution to knowledge for integrated infrastructure planning.
Action volume ratio: a method to classify the danger of lightning in any given volume
(University of the Witwatersrand, Johannesburg, 2015-05-07) Dickson, Andrew Stuart
The annual number of injuries and fatalities from lightning has, over the last century, been on a steady decline. This is primarily due to urbanisation and movement away from agriculturally intensive activities. In countries with a high urban population, the incidence of lightning fatalities is below 1 death per million people per year. However, in countries with a larger rural population, this rate is significantly higher, ranging between 8 and 15 deaths per million people per year. There has been a large drive towards educating the general public about the dangers of lightning and methods to avoid being in a dangerous situation. However, fatal lightning events still occur on a regular basis. There are currently no methods to determine the risk of lightning to living beings in open spaces. The international standard (IEC 62305-2) provides a method for the assessment of risk to living beings within a structure, and up to three metres outside of it. Considering that the majority of deaths by lightning occur outdoors, a method of determining these risks is necessary. The Action Volume Ratio (AVR) is proposed as a new method for the analysis of the danger of lightning in any volume. It considers the dangers of all lightning injury mechanisms in relation to the objects in the space, which are assumed to be the preferential points of strike. A union of the dangerous volumes is then formed, and a ratio to the total volume is created. The AVR uses accepted electrical engineering equations to determine the dangerous areas, and places no reliance on probability theory, which can, in many cases, skew the results of a lightning risk analysis process. The AVR can be combined with lightning ground flash density data to indicate the incidence and frequency of dangerous events within a given volume.
An application of John Rawls' principles of social justice to planning: issues arising from the implementation of the national housing subsidy programme in the inner City of Johannesburg
(2024) Oelofse, Michael Gerald
John Rawl' s conception of social justice has had a fundamental influence on liberal ethics yet its practical implications for distributive planning have rarely been considered in any comprehensive way. This is the key contribution of this thesis. Using the South African housing subsidy system, it examines how distributional policies may be structured to benefit the least advantaged and explores the consequences of their implementation in Johannesburg's inner city. Based on a literature review, it argues that Western planners often place the responsibility for distributional decisions on political processes, or concern themselves with maximising the public good without addressing the consequent allocation of the costs and benefits among members of society. Contemporary planning theory continues to avoid the substantive c.9ntent of social justice. Confronted with what seem to be equally valid, often competing conceptions of social justice, planners focus on the fairness of planning procedures instead of taking normative, principled positions on distributional outcomes. However, just procedure alone does not guarantee a just outcome. This requires adherence to some predefined set of distributional principles, and Rawls' political conception of social justice is presented here as a reasonable and compelling option for planners. Drawing on the author's practical experience, this thesis traces the liberal influence on the formulation of housing subsidy policy in South Africa and argues that national policy generally conforms with Rawlsian distributional principles. However, an empirical analysis of the housing sector in Johannesburg's inner city reveals that its impact is dissipated by a lack of local commitment to the original principles. Conflicting development principles and a failure among many residents to honour the obligations attached to housing benefits compound the problem. This thesis concludes that Rawlsian principles of social justice in combination with the contemporary communicative turn in planning provide planners with a powerful means of placing social justice on the development agenda, but that these principles require championing because conflicting principles and interests continuously place the needs of the least advantaged at risk.
Analysis of the developmental potential of artisanal and small-scale mining: a strategy for South Africa
(2024) Twala, Pontsho Francinah
The mining industry remains central to the socio-economic development of mineral economies. While this is the case, most African countries have been struggling to translate the benefits of mining into positive developmental outcomes. This has been attributed to several factors including the failure to leverage opportunities from the Artisanal and Small-Scale Mining (ASM) sector which has been growing in most countries. As is the case in other African countries, the mining industry continues to play a considerable role in South Africa’s economy. The industry is expected to contribute significantly to the country’s socio-economic agenda which aims to eradicate poverty and inequality by 2030. Despite the positive outlook, the performance of the industry has been declining resulting in the government identifying a series of interventions aimed at reviving the industry’s activities. Amongst these is the formalisation of the ASM which has been earmarked for job creation and poverty alleviation. The objectives of the Thesis were to establish the developmental potential of ASM in the country, and subsequently develop a strategy framework aimed at enabling the sector to contribute to the mining industry and national development plan. The study was conducted using multiple case studies with data collected and analysed using multiple methods. The major finding from the study is that the ASM sector has the potential to contribute towards the country’s development priorities. This is taken from the evidence that shows a direct link between the sector’s activities and the country’s socio-economic landscape. It was established that the main drivers of ASM are socio-economic challenges in the country, mainly growing unemployment and poverty levels. To this end, ASM is playing a role in providing livelihoods to country’s population is that most affected by poverty and unemployment. As a livelihood strategy, ASM has improved the poverty status as well as the living standards of those that participate in its activities. The evidence from the study revealed that most of the miners measure above the country’s subsistence level and can provide for themselves and their families. The benefits of the sector also extend to communities and overall, these can be linked to several objectives as captured in the country’s development plan. The conclusion from the study is that the developmental potential of ASM can only be leveraged if the challenges in the sector are addressed, and these encompass issues relating to the regulation of the sector, mining land and mineral resources; value chain constraints, and related support, responsible practices, institutional arrangements, and ASM stakeholder relationships.
Application of derivative techniques to improve the forecasting of price volatility of copper, gold and platinum metals
(2024) Veriyadi, Veriyadi
This research investigates the forecasted price volatility of copper, gold and platinum metals based on the selected companies; Palabora Copper Mining Ltd, AngloGold Ashanti Ltd, Gold Fields Ltd, Sibanye-Stillwater, Anglo Platinum Ltd and Impala Platinum Ltd. In responding to the latter sentence, single price volatilities are dual volatilities, where dual volatilities comprise of financial and technical variables. The selected firms either have global operations or they are subsidiaries of global companies. Dual volatility is computed using a Sample Correlation Coefficient and in order to explore the dual volatility, this research introduces three hypotheses. The first hypothesis uses a Decision Tree Analysis to test dual volatility based on financial and technical variables (e.g., mineral commodity price, metal grade, operating cost and production rate) in improving the forecasting of price volatility of copper, gold and platinum metals. For validation, the first hypothesis uses the Markov-Regime Switching Model. The results of this hypothesis illustrate that dual volatilities are more accurate and robust than price only volatilities. Then, the second hypothesis examines dual volatility using a GBM model. This hypothesis tests dual volatility; which is computed based on financial and technical variables (e.g., oil price, copper price, oil production and consumption, copper production and consumption; and the exchange rate from U.S.$ to ZAR and gold and platinum price data). The chosen variables that affect the dual volatility are examined using a Multiple Regression Model and that model confirms that those variables are independent in principle. Finally, the third hypothesis estimates future profits based on a binomial tree, which has risk-neutral probabilities based on dual volatility using mineral commodity price, metal grade, operating cost and production rate. The results of risk-neutral probabilities using dual volatility are less optimal than a mineral commodity price volatility due to not accounting for the mean of logarithmic returns. The robustness test uses the VAR model, which indicates that the profits react differently to different shock stages from revenues, risk-free interest rates and profits. In conclusion, dual volatility can improve future price forecasting performance because duality is underpinned by different variables, which include independent variables from the global commodity markets. The forecasting performance improvement from dual volatility in predicting the future price can be shown by the lower value of the Root Mean Square Error and Mean Absolute Percentage Error results than a mineral commodity price volatility. The findings of this research apply to copper, gold and platinum metals for mining around the globe.
Comparative study of five country-specific labour-intensive infrastructure development programmes : implications for South Africa
(University of the Witwatersrand, Johannesburg, 2010) Quainoo, Harry Akyen; McCutcheon, R.T.
Unemployment and abject poverty in South Africa are widespread, persistent and disproportionately high. These problems are aggravated by inadequate capacity at all tiers of government and huge infrastructure backlogs in rural South Africa. Employment-intensive means of infrastructure delivery have been successfully implemented in several sub-Saharan African countries and elsewhere to generate employment and reduce poverty. It should be possible to replicate similar large-scale national programmes in South Africa. But South Africa has failed. Both prior to and since 1994, several supposedly employment-intensive programmes have been implemented in South Africa with poor results. In an endeavour to contribute to future South African policy and good practices regarding employment, this thesis describes and analyses in detail five major Sub-Saharan programmes and reaches conclusions regarding their achievements and shortcomings. Lessons derived bridge the knowledge gap between the large-scale programmes embarked upon in the sub-Saharan countries in the mid-1980s and the year 2007; these lessons should be applied to future endeavours in South Africa to generate significant employment per unit of expenditure and contribute to poverty alleviation. A major conclusion reached was that the success of employment-intensive infrastructure development programmes depends to a large extent on fundamental factors such as appropriate and implementable policy, government commitment, adequate and sustainable funding, adequate capacity and good preparation. Specifically, the thesis demonstrated that prior to implementation a sufficient timeframe is required for programme preparation in order to make significant contribution towards poverty reduction. Equally, national programme expansion requires a strategic balance between centralisation and decentralisation. In particular, for programme extension and decentralisation, due regard must be given to training and capability building and available resources. Deriving from the thesis’ major conclusions, the author developed three crucially important frameworks for anti-poverty infrastructure development programmes, namely; a four-phased model for evaluating the chances of success of infrastructure programmes, a five-phased result-oriented guidelines for testing the workability of infrastructure development policies, and a practical guideline for monitoring and evaluating employment-creation programmes that maximises the benefits thereof and pre-empts institutional memory loss through systematic knowledge management.
Discrimination between nearby and direct lightning strikes to a long operational medium voltage line to assist in the determination of the basic insulation level (BIL)
(University of the Witwatersrand, Johannesburg, 2022) Van Schalkwyk, Willem Jacobus Dirkse; Gomes, Chandima; Van Coller, John
The lightning performance of a Medium Voltage (MV) line needs to be divided into two categories: lightning performance due to nearby lightning and direct lightning strikes. A better nearby lightning performance requires a higher Basic Insulation Level (BIL) while the direct lightning performance requires a lower BIL to minimize equipment failure. The electromagnetic coupling models for calculating the Lightning Induced Overvoltage (LIOV) on a line are complicated and reliant on accurate input data. Therefore, short floating lines (< 3 km) were used to calculate the line’s lightning performance. The models were then verified with LIOV measurements on these short floating lines and the results were normalized to estimate the lightning performance of long operational lines. These estimations for long lines could never be verified due to the complexity of calculations and the cost and logistics of equipment to do measurements on long operational lines. A new methodology to measure the lightning performance of a long operational line was developed and verified. The obstacles such as the long line length, the changing soil resistivity, the lightning channel properties and the rapid attenuation of the LIOV along the energized line have been used as an advantage in the new method. The finite soil conductivity was used as an advantage to distinguish between nearby lightning and direct lightning strikes while the power frequency current was used to determine whether the LIOV exceeded the line BIL and caused a line fault. An existing electromagnetic coupling computer model, the ATP-EMTP, was verified with the existing ERM using the same input data. The ATP-EMTP model was then extended to include the equipped long MV line. There was no existing model or measurements to which the results could be compared to. Actual nearby lightning and direct lightning strikes of which the termination point was known were used to verify the new methodology. A significant size database (consisting of 38 675 lightning flashes and 1 155 line faults over two years) was used to evaluate the IEEE Std 1410-2010 estimated lightning performance of the long line.
Food security in rural areas: the case of the Umkhanyakude District Municipality in the Northern Region of KwaZulu-Natal
(2024) Nhlozi, Mduduzi W
Studies on food security focusing on households began attracting considerable attention in the mid-1970s following a surge in the cost of food production and food prices. The surge in prices led to increasing percentage of food insecure households throughout the world. To address the growing number of people affected by hunger, countries sought to develop new technological techniques to produce food in large quantities particularly in the developing world. The thrust of the approach was to ensure the availability of food first. The understanding was that large food quantities would result in food-secure nations. Overtime, researchers realised that improved food production does not lead to food secure households. Since then, the percentage of people affected by hunger has continued to increase with 690 million (8.9%) considered food insecure in 2020 (Food Agriculture Organisation – FAO, 2021) despite relative increase in food production. South Africa is not an exception with 23% of the population reported food insecure in 2020 (van der Berg et al., 2021). The reports by the NIDS-CRAM have indicated that the outbreak of coronavirus pandemic in 2019 has further exacerbated food insecurity at a household level. The purpose of the study is to explore mechanisms used by rural households to achieve food security during various threats and risks to their livelihoods. The case study adopted is the Umkhanyakude region which is in the rural area of northern part of KwaZulu Natal. It covers an area of 13855.35 km² and accommodates approximately 625 846 people constituting a total of 128 195 households (Stats SA, 2011). The region was selected as a case study due to its economic, social, demographic and ecological characteristics. The study uses semistructured questionnaire to collect information on lived experiences of households in their quest to access and ensure availability of food. The study finds that households use several food strategies namely economy-related, culture-related and rite-of-passage to achieve food security. The strategies are framed within the context of what Nee and Ingram (1998) refer to as new institutionalism or new institutional economics. New institutional economics places focus on the importance of a “web of interrelated norms – formal and informal” that govern how individuals and households in Umkhanyakude region “respond to perception of costs and benefit in exchanges and invest in or divest themselves of particular ties” (Nee and Ingram, 1998: 19). The study argues that these strategies are embedded within social norms, values, and cultural practices beyond the ambit of orthodox economics. It further argues that the discourse on food security in rural areas must be framed beyond the economic analytical framework, to reckon with the embedded social and cultural norms, practices, rules, and relationships and to develop salient policy interventions. The study advocates for the development of localised food security plans by local municipalities to improve food security status of rural households. This is because food insecurity is largely felt at community and household levels. It is important that policy frameworks to manage food security are placed at municipal levels where local communities can easily access them.
Governance of infrastructure provision in informal settlements: the electrification of unproclaimed areas in the City of Johannesburg
(2022) Chikomwe, Savory
An increasing number of informal settlements in South Africa are receiving interim services for extended periods while awaiting permanent upgrading or housing solutions. This thesis explores the complex governance arrangements and challenges that arise around the provision of basic services using City of Johannesburg as a case study, with a focus on three ‘unproclaimed’ informal settlements that have undergone electrification. These are Stjwetla, Protea South and Slovo Park. The three cases shed light on the modes of infrastructure governance that characterize informal settlement upgrading as practiced in the City of Johannesburg and to some extent in South Africa more generally. Formal grid electrification in the case study settlements is juxtaposed by other temporary basic infrastructure provisioning in a complicated socio-political, institutional and governance context. The inquiry adopted a qualitative methodology. The case studies of the three settlements and the City of Johannesburg were compiled through an extensive literature and document review and indepth interviews with key informants. These spanned community leadership, political representatives, experts and officials in municipal, provincial and national departments and stateowned entities. The thesis finds ambivalence, disconnections, misalignments and contradictions in the basic infrastructure provision and upgrading processes within the City of Johannesburg and between the City and central government departments. This was accentuated by the role of the national state-owned electricity company Eskom in one of the three settlements. The thesis finds that the prolonged temporary status of the informal settlements promotes contestations at various levels, including ligation. In the absence of progress towards permanent upgrading, investment in grid electrification ambiguously signals permanence even where there is no state intention to upgrade in situ. Within communities, this confusion contributes to tension while also triggering consolidation and in-migration. Differing interpretations across entities of the state about the role of grid electrification in informal settlement trajectories open up space for temporary electrification ultimately to lead towards the pragmatic adoption of permanent in situ upgrading. This notwithstanding, literature reviewed for this thesis points instead toward the necessity for a turn to off-grid electrification technologies for informal settlements.
Peak-to-average power ratio reduction in optical-OFDM systems using lexicographical permutations
(University of the Witwatersrand, Johannesburg, 2023) Niwareeba, Roland; Cox, Mitchell A.; Cheng, Ling
The work presented in this thesis extends and contributes to the research in reducing the high Peak-to-Average Power Ratio (PAPR) in optical-Orthogonal Frequency Division Multiplexing (OFDM) systems using probabilistic-based and hybrid techniques. Whereas the high PAPR problem has been extensively studied and a number of solutions provided for the conventional Radio Frequency (RF)-OFDM systems, there are only a few solutions proposed specifically for PAPR reduction in optical-OFDM systems. Although the probabilistic-based techniques such as Conventional Selected Mapping (CSLM) and Data Position Permutation (DPP) result into significant PAPR reduction performance with negligible Bit Error Rate (BER) degradation, the resulting increase in both hardware and computational complexity as a result of a large number of Inverse Fast Fourier Transform (IFFT) operations that have to be performed to generate the candidate signals is still a major drawback. In order to reduce the complexity, in this research, two techniques which are applied in opticalOFDM systems are proposed. The first technique is the hybrid method composed of a modified CSLM and µ-law companding techniques called Low Complexity Hybrid Selected Mapping (LCHSLM). The proposed method achieves almost 50% reduction in complexity compared to CSLM with less BER degradation. The second technique based on lexicographical permutations called Lexicographical Symbol Position Permutation (LSPP) works by dividing the optical-OFDM symbol into a number of sub-blocks and performing lexicographical permutations to obtain the candidate signals after the IFFT operations. In the proposed LSPP, all the candidate permutation sequences are not obtained at once unlike in the DPP where the number of candidate permutation sequences increases at a factorial rate of growth as the number of sub-blocks increases resulting in a more complex system. Additionally, the research proposes an algorithm where a threshold PAPR value is introduced and the candidate signals are generated until a candidate with a PAPR value less or equal to the threshold is obtained. The results show that the complexity in terms of IFFT operations can be reduced substantially depending on the selected threshold and the number of candidate signals. Furthermore, the research introduces a new algorithm based on the global gain (net gain) to determine the most suitable number of permutation candidate sequences to achieve a reasonable PAPR reduction performance without increasing the time and hardware complexity to levels that the systems cannot tolerate.
Pegmatite investigations in the Karibib district, South West Africa
(University of the Witwatersrand, Johannesburg, 1963) Roering, Christian
The outer pegmatitie zone of variable thickness which is essentially a very coarse-grained granite consisting of larger perthite phenocrysts lying in a matrix of albite, quartz and muscovite. The inner portions of this zone may reveal a great enrichment of perthite, so much so, that it may grade into a giant perthite zone, e. g. Rubicon main ore-body; Karlsbrunn close to the Li-bearing ore zones. This outer portion of the pegmatite may also reveal a subdivision into two distinct units: an outermost zone of albite-quartz-muscovite and an inner zone of albite-perthite-quartz-muscovite. This sequence of essentially granitic crystallization is often abruptly broken by the appearance of a zone consisting essentially of cleavelandite with minor quartz and muscovite. This zone is characterized by the appearance of numerous accessory minerals often in economic quantities, e. g. beryl, columbite-tantalite-frondellite, topaz and apatite. The zone is generally of the order 1-5 feet depending on the original size of the pegmatitie and the degree of fractionation. That it is not a late replacement unit is confirmed by observations at Rubicon where corroded crystals of beryl belonging to this zone are found lying in a matrix of lepidolite and albite which is the next unit to form. The lepidolite-albite zone in fact replaces the beryl-bearing zone. The striking symmetry alone of the Rubicon body testifies to this zone preceeding in crystallization sequence the Li-ore zones. The significant fact about this zone is that it marks a distinct break in the crystallization history of the pegmatite, i. e. it marks the change from crystallization of essentially granitic components to the formation of late phase constituents, viz. Li-bearing and associated minerals. It possibly marks the break from magmatic crystallization to late-magmatic conditions when pneumatogenic and even hydrothermal processes begin to operate. The next group of minerals to form are noticeably rich in Li and are frequently associated with sugary albite. The major minerals are petalite, lepidolite and albite, while minor amounts of amblygonite also occur. There is a definite spacial relationship sequence in the formation of these minerals. Petalite crystallizes first and collects in the upper part of this unit generally forming a hood. Amblygonite, albite, quartz, may occur at the same time. Immediately below this petalite hood, and at a somewhat later stage, fine-grained lepidolite crystallizes together with albite and minor quartz. The final phase to form at this general stage is sugary albite which collects at the bottom of the still non-crystalline portion of the magma chamber. The sugary albite phase is able to behave diapirically and can intrude, brecciate, and replace any of the previously crystallized zonal constituents. Each successive stage here can assume corrosive relationships to previously consolidated units. No assessment is made as to the amount of replacement that may take place as the criterion commonly used for such diagnosis are somewhat subjective. During this entire process of complex diffusions and crystallization, silica is apparently being concentrated in the residual fractions of the pegmatite magma. The next zone to form is a cleavelandite-rich rock confined to the quartz core margin. This cleavelandite is able to vein and brecciate and corrode the immediately adjacent lying lepidolite and is often associated with minerals such as beryl, columbite, tantalite, tourmaline, topaz and apatitie. Amblygonite may also belong to this stage of mineralization though in general it tends to be associated close in time with the petalite stage of mineralization. The final stage of the crystallization sequence is the quartz core. Quartz veinlets emanating from the core have been observed to cut across adjacent lepidllite-rich and amblygonite-albite zones. Euhedral crystals of columbite and beryl at the core margin are completely surrounded by quartz. These observations may suggest that quartz, although concentrated in the centre of the dyke, probably existed in some unconsolidated state (e. g. a gel as Brotzen (1959) has suggested). The development of a gas phase at certain stages of the pegmatites consolidation history possibly accounts for the vertical fractionation found in these pegmatites. Finally details of the more important pegmatite minerals are given together with chemical analyses.
Post-1994 South African university infrastructure: a critical study of the framework and spatial principles to guide future developments
(2024) Hansen, Ludwig
Due to the lack of institutional guidelines for the development and expansion of universities in South Africa a need exists to study and understand the key challenges facing its 26 universities. This doctoral research evolved from the researcher’s urban design and architectural work in practice which, over the past fifteen years, has included urban design for a number of university campuses and their spatial development frameworks. Through this practice-based work it became clear that no institutional guidelines for the development and expansion of universities in South Africa exist. A need was therefore identified for the study of existing campus master plan documents and international campus planning literature to pinpoint the elements, principles, configurations and methodologies in order to guide universities in producing integrated spatial design and development frameworks for their campuses. Apart from a lack of guidance from national government, the increasing pressure on the national fiscus to provide funding for the expanding needs of universities is forcing institutions to re-consider methodologies towards expanding, improving and implementing their infrastructures, buildings and spaces. These alternative planning methods also imply broader partnerships to ensure long-term sustainability and relevance within the South African context. The role of collaboration with the host city or community is becoming increasingly relevant and the development of ‘place-based universities’ must be seen as critical in order to ensure long term sustainability. Recent international research demonstrates that universities are valuable stakeholders within their broader context, making them instruments of regeneration in engaging future developmental necessities. In light of the above, the research objectives are in principle three-fold. Firstly, to establish what spatial principles guide well-functioning university campuses; secondly, which methodologies are used to achieve this; thirdly, to research approaches towards achieving improved integration and collaboration of university campuses with their host cities, communities and stakeholders. The research methodology in this study focuses on the literature review dealing with the historical development of universities and the analysis of their spatial forms, as well as in-depth reviews of 25 contemporary university campus masterplans from across the world, in order to establish normative spatial design guidelines. These findings are then used to analyse the 26 South African universities with their 92 sub-campuses in order to offer improved insights into their challenges and characteristics. The same principles are also used to assess and reflect on the researcher’s practice-based work, with a specific focus through in-depth case studies of the University of the Witwatersrand, the University of Johannesburg (especially the Rand Afrikaans University campus) and the recently established Sol Plaatje University. This thesis is organized in three parts, featuring eight chapters. The first part outlines the research problem, including the review of relevant literature and adopted methods of inquiry. The second part covers the analytical study, including case study descriptions, categorisations and performance analyses. Finally, the third part summarises and discusses the results of this research project and makes an institutional recommendation on how these can continue to be taken forward in both practice and research
Reducing water absorption characteristics of kraft paper reinforced with modified nanoparticles
(University of the Witwatersrand, Johannesburg, 2023) Katun, Mohammed Mahmood; Nyamupangedengu, Cuthbert; Gomes, Chandima
The inherent hydrophilic characteristics of cellulose wood fibre compromise the dielectric properties of kraft paper insulation that is used mainly in oil-insulated power transformers. This thesis, therefore, presents a novel material design model of nanocomposite kraft paper with improved hydrophobic properties for power transformer insulation applications. The concept of nanodielectric kraft paper design was used. Rutile-titanium dioxide nanoparticles (rutile-TiO2 NPs) were selected as the nanofiller. Compared with other metal-oxides, rutileTiO2 NPs are stable in chemical reactions, have good thermal stability and also have high electrical resistivity. Rutile-TiO2 of 19.72 nm diameter were fabricated using the sol-gel method and then used in reinforcing the kraft paper to produce a nanocomposite kraft paper with improved dielectric properties. Since the nanoparticles are inherently hydrophilic, and the intention is to produce a hydrophilic nanocomposite kraft paper, a technique was devised to make the NPs hydrophobic. The rutile-TiO2 NPs were surface conditioned with two alternative surfactants; Alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA). Various quantities of the two surfactants were investigated to determine the optimal amount. The resultant surface-modified rutile-TiO2 NPs were studied to understand their hydrophilicity and thermal stability properties. It was found that the unmodified rutile-TiO2 NPs absorbed more moisture, compared with the surface-modified nanofiller, the mass increased by about 4% due to moisture absorption. The surface-modified rutile-TiO2 NPs with 5% AKD had 45% more thermal resilience than the unmodified rutile-TiO2 NPs surface and this is a significant knowledge contribution of this thesis. Using an unbleached kraft pulp, nanocomposite kraft paper specimens were fabricated with nanoparticles having varying surfactant loading. The specimens were then characterized to reveal various critical properties such as hydrophobicity, thermal, dielectric losses and dielectric strength. The version of the nanocomposite kraft paper that gave the most improved water and moisture absorption properties was that with 5vol/vol% ASA surface-modified NPs. The moisture absorption rate dropped by 74% compared to the unfilled kraft paper, and the water vapor transmission rate decreased by 30%. The contact angle of water droplets improved by 12%, and water absorption rate improved by being 4 times slower. The dielectric loss measurements showed that the nanocomposite kraft paper containing rutile-TiO2 NPs (5 vol/vol% ASA) also had 40% lower dielectric losses than the reference (unfilled) samples. The breakdown voltage of the nanocomposite kraft paper increased by about 15% while thermal withstand was improved by 5.4%. This research, therefore, has successfully improved the hydrophobic properties of kraft paper by filling it with surface-modified rutileTiO2 NP. It can be argued from the results that for power transformer application, the novel nanocomposite kraft paper developed in this thesis will improve power transformer insulation reliability design by mitigating the main agents of insulation degradation which are water and thermal stress.
The polymorphic state and real estate: rethinking the relationship between the state and real estate through Johannesburg & Bangalore
(2022) Pillay, Sarita
This research seeks to expand understanding of the relationship between the state and real estate. It is guided by the impulse, from experience in urban land justice activism, to acknowledge multiplicity in the state, and to contextualise the nebulous boundary between the private and public. I argue that commonly adopted concepts in critical scholarship – in the strands of urban power, urban planning and historical materialism – do not adequately offer a means to do this. Thus, drawing from how these concepts have been stretched and refuted in critical scholarship, an analytical lens is assembled for this research. It is guided by three influences: a historical materialist analytic of the urban; non-normative approaches to a postcolonial state theorised in India; and insights on the amorphous boundary between the state and private sector in real estate The starting point for this research is Johannesburg. However, an expansive spectrum of Indian critical scholarship surfaced in reading the relationship between the state and real estate. This raised the methodological utility of bringing Johannesburg into empirical conversation with an Indian city. Emerging organically as this city was Bangalore. Rather than ‘cases’, Johannesburg and Bangalore are approached as ‘vantage points’ through which to explore the relationship between the ubiquitous, albeit socially constructed, state and real estate. This research was thus guided by the question: (How) can the relationship between the state and real estate be conceptualised through Johannesburg and Bangalore? To begin to explore this, I undertook in-depth interviews with 62 key informants in real estate and government, as well as observations in real estate conferences and as an intern in a real estate consultancy firm. Additional analysis was undertaken of news articles, industry reports and building statistics. Three lesser-seen relationships between the state and real estate emerged, grounded in each city but developed through each other: an enabling relationship between local government and real estate shaped by the post-apartheid transition in Johannesburg; central government’s incorporation of real estate in Bangalore; and the Government Employees Pension Fund’s (GEPF) embeddedness in Johannesburg real estate as an ‘investor state’. In a landscape of differentiated real estate, the state was shown to be central to financialised forms of real estate – but not only so. This contributes to conceptualising a polymorphic state and real estate. Empirically, this work expands critical scholarship to direct considered attention to non-corporate forms of real estate in India, and listed corporate real estate in South Afric
The Quantitative Hydrogeological Mapping of Zebediela Estates, Central Transvaal
(University of the Witwatersrand, Johannesburg, 1970-05) Pretorius, Desmond Aubrey
The groundwater system on zebediela Estates, situated along the northern edge of the Springbok Flats in the Central Transvaal, has been studied by physiographic, geologic , geophysical, geochemical, and hydrologic methods . Emphasis has been placed on the subsurface mapping of the spatial distribution patterns of a nvn1ber of hydrogeologic parameters, and computer-based polynomial trend surface analysis has been employed to facilitate the interpretation of the maps. The computer has also been used to determine the general statistics of the frequency distributions of the various parameters and to platform sequential multiple linear regression analysis in an attempt to determine the relationships between the variables . Data arrays of observations, computations, and interpretations have been disp layed in 38 tables in the text and 21 appendices to the text . The distr ibution patterns , in one and two dimensions, have been portrayed in 8 text figures and 117 maps, separate from the t ext. The area studied covers approximate ly 23 square mil es, in which 556, 000 orange trees have been planted on 5800 acres . An average annual amount of 2400 million gallons of water is required to maintain t he operation, and 560 million gallons of this quantity are withdrawn, on the average, each year from boreholes tapping the groundwater resources of the Estates . Up to April, 1969, 315 holes had been drilled, and 151 had become producers at one time or another. In 19 years of exploitation between 1950 and 1968, 10, 600 million gallons of groundwater were withdrawn, at an average rate of 13 million gallons per year per production borehole. The study has shown that the groundwater system supplying this substantial quantity of water consists of two main elements - a piedmont alluvial slope, in which stream channels and paleochannels on coalescing alluvial fans are acting as conduits for the transmistion of water from the intake areas; and an underlying bedrock storage reservoir composed of aquifers of the Transvaal and Karroo sequences . The Malmani dolomite aquifers and the Stormberg basalt aquifers are superior to those of the Wolkberg quartzites, shales, and lavas, and the Stormberg Cave sandstones. It has been possible to distinguish two cycles of Karoo basalts, each of which shows differentiation . The upper cycle is far more important as an aquifer than the lower cycle. The piedmont slope is composed of portions of three alluvial fans , the spines of which have a general southeasterly trend towards the junction of the Nkumpi and Olifant rivers in the valley-flat environment well to the south of the Estates . The upland areas above the apices of the fans embrace the mountain ranges which form the northern rim of the Transvaal Basin, and these uplands have suffered right-lateral movements along extensive east-northeast-trending transcurrent faults which must have continued to be active into recent times in order to displace the stream course on the fans. The fan-head section and portion of the midfan section of the Nkumpi fan, in which the Gompies River is situated, occur over the east-central, eastern, and southeastern parts of the property, and, where underlain by the upper basalt aquifers, constitute the most important source of groundwater on Zebediela Estates. The whole of the fan-head and mid-fan sections of the Mamukebe fan are located in the riorthern, west-central, western, and southwestern localities of the area studied. The fan is much smaller than either of the others, and is underlain by Wolkberg rocks, Cave sandstones, and lower basalts. Its overall groundwater potential is consequently lower than that of either of the other two components of the piedmont slope. Only a very restricted portion of the fan-head section of the Mogoto fan occurs in the extreme northwestern corner of the Estates, where it is underlain by the dolomite aquifer, Its groundwater parameters are consequently very favourable, but the true potential of this fan lies beyond the western boundary of the property. The average yield of boreholes in the upper basalt is 3600 gallons per hour; in the lower basalt, 2000 g.p.h.; in the sandstone, 1500 g.p.h.; in the dolomite, 11,200 g.p.h.; and in the quartzites, 1500 g.p.h. The average yield for all boreholes on the Estates is 4100 gallons per hour. All of these figures are appreciably higher than those for equivalent formations elsewhere in South Africa, testifying to the impoi,tance of the piedmont alluvial slope environment in the overall groundwater system at Zebediela. The average annual recharge of the groundwater reservoirs from all sources has been estimated at 700 million gallons. With the average annual withdrawal being of the order of 560 million gallons, the possibility exists that production from the aquifers can be increased by 25 per cent, without fear of serious, permanent deterioration in the performance of the groundwater system. However, excessive exploitation in times of low recharge might lead to the development of quality h.azards with respect to sodiuum, ehloride, and bicarbonate over the upperbasalts. This possibility does not exist for the remaining aquifers, particularly those in the dolomite, from which relatively pure water is drawn. An added problem in the recharge of the upper basalt aquifer is the contamination of t he groundwater in storage by lithium, brought into the Zebediela groundwater- system by the Nkumpi River, which transmits the element from the granite terrain to the north of the mountainous rim of the Springbok Flats. A new model of groundwater exploration has been devised, based on optimum drilling sites being located where coincidence takes place of piedmont stream channel conduits, dolomite or upper basalt aquifers, and transcurrent fault aquicludes, Results obtained from the employment of this model during two years of drilling subsequent to its development in a preliminary form produced an increase of 14 per cent in the average yield of all boreholes drilled.
The theory and practice of community participation in provision of urban structure
(University of the Witwatersrand, Johannesburg, 1993) Abbott, John; McCutcheon, Robert
The thesis develops a new approach to community participation, for application to infrastructure provision projects in developing countries, based upon social surveys and case studies of negotiations in five South African communities. Existing approaches to community participation are analysed and shown to be unsuitable for infrastructure provision. The thesis compares the characteristics of infrastructure projects with those of other types of development projects and demonstrates how these characteristics can be used to situate a given project within a project environment defined in terms of two variables: the openness of government to community involvement in decision-making, and project complexity. Social surveys carried out in Soweto and KwaThandeka showed the centrality of infrastructure to social change in South Africa. Existing urban management systems were unable to cope with the stresses placed upon them. Four facets of urban management were identified as being under stress: institutional capacity, legitimacy, affordability, and user convenience. These stresses change the nature of infrastructure provision from the supply of end products into a complex process. Central to this process are: an increased number of actors influencing decisions, the enhanced role of technical professionals, and the social implications of different levels of service. The case-study of KwaThandeka included a study of the negotiation process with the provincial administration. This research led to the development of a performance specification for comparing social, economic and technical measures of value. A new conceptual framework for community participation was derived, based upon the different actors involved in the decision-making process and the different needs of each of those actors. Three case studies from Natal identified different implementation strategies for community participation. Communities were found to have three distinct needs: involvement in the political process; involvement in technical decision-making; and representation as consumers of services. An analytical tool was developed to assist project managers in understanding the relationships between actors in a project. The thesis shows how technical project management can be integrated into the participation process. The success of community participation can be evaluated by assessing the degree of consensus achieved between actors, and the intensity of community involvement.
Urban scripting audio-visual forms of storytelling in urban design and planning: the case of two activity streets in Johannesburg
(2024) Mkhabela, Solam
South African cities reflect spaces based on Euro-American theories and norms, mapping methods, and design imperatives. At a local level, this imposition’s tool of static diagrams, plans, sections, elevation, and aerials; broader spatial plans with localized frameworks; regulatory plans controlling land use results in spaces hindering socio-economic development, especially for the marginalized, which comprises a predominantly black African and poor cohort. Consequently, current practice must significantly improve a city’s engagement with everyday users. Based on the indicated need, this thesis argues that the first step to effective urban design is accurately ascertaining spatial needs. In responding to current city-making practices that create ineffective spatial outputs, the study introduces Urban Scripting as a novel transdisciplinary and practice-based approach for assessing inhabitable urban locations. Its methodology in city-making processes strategically inserts social narrative to enhance understanding of daily user experiences. In creating accessible ways of exposing urban layer details, the procedures combine Nguni oral tradition (local expertise) with audio-visual (disciplinary knowledge) as a hybrid narrative technique that simultaneously analyzes and produces. Here narrative suggests using story to amplify an evolving discourse unit that writes and communicates spatial imagination. More so, storytelling, framed in and through interaction, finds people and information often missed by conventional mapping and assessment tools, specifically the voices in the ‘twilight zone,’ the space between legal and illegal on-the-ground operations. Transdisciplinary methods structure more critical and empirically on-ground evidence that inductively leads to new ways of thinking and analyzing. Practice-based casework turns space into place, builds an anthology of empirical knowledge to inform city-making methodologies, and shapes appropriate policies supporting subaltern communities. Programmatically and polemically, it explores how a cinematic frame is an inclusive tool within a specific set of urban processes. Ultimately, its enframing application calibrates an empathetic narrative, potentially transforming lives better for an African city in motion. This approach is valuable for practitioners as a firm departure from convention and thrusts Black African knowledge to the forefront, thus acting as a decolonization tool. Tested at two different sites in Johannesburg, Alexandra (formerly a Black dormitory ‘township’) and Orange Grove (once a whites-only area), the approach effectively engaged with spatial users, specifically, the microentrepreneurs whose urban insurgency practiced on the side of the street serves the broader public yet remains unnoticed by spatial practice. Urban Scripting’s methodology better understood the urban spatial challenges and needs at the Johannesburg study sites. For spatial practice site assessment, theory building, and iv practical application, it is an approach that is likely to prove equally effective in communicating bottom-up needs to help imagine and design a fair and democratic city in hundreds of other similar environments in South Africa and indeed, across Africa, where parallel realities exist.
Why do equity oriented, ‘progressive’ planning policies fail to redress the apartheid city? An examination of Planning Instrumentality in South Africa
(University of the Witwatersrand, Johannesburg, 2023-09) Klug, Neil; Bénit-Gbaffou, Claire; Todes, Alison
In the immediate post-apartheid period, the fields of urban planning and housing experienced what some have called a ‘golden era’ during which planning played a significant role in the Reconstruction and Development Programme of the government, through developing new and progressive planning and housing policy instruments. Some of these instruments were designed to expedite the release of serviced land and provide subsidised housing, address the apartheid legacy of spatial segregation and housing backlogs. Despite success in the large number of houses delivered to the poor and increased service delivery to previously disenfranchised communities, by the mid 2000s there was growing criticisms of the state’s failure to redress discriminatory apartheid spatial patterns. South Africa was also experiencing growth in unemployment and inequality between emerging elites on the one hand and the majority of previously disadvantaged in society. This study sought to examine what role planning policy instruments played in failing to address the spatial legacies of apartheid. Acknowledging the wide range of potential variables contributing to this lack of efficacy, the study took an in-depth grounded, research approach. Using three case studies on different planning and housing related policy instruments and suits of instruments, at different phases of the policy cycle framework, it examined whether or not the state had managed to address housing and other inequalities. The first case study involved the examination of the processes and practices in formulating a local eviction policy instrument, the second reflected on housing officials’ engagement with the National Housing Code suit of instruments, and the third examined the practices and processes of implementing the Upgrading of Informal Settlements Programme. The findings of these case studies were that equity oriented, ‘progressive’ planning policies fail to redress the apartheid spatial inequalities because they are either not being selected for use or, where they are being applied, had limited impact because they were being implemented in a watered-down fashion. My thesis shows that there are multiple factors, from broad and complex governance structures to the actions of individual actors, that affect the efficacy of policy instruments.
Why do people walk on this street?: comparing quantitative and qualitative measures of imageability and their association with pedestrian patterns
(2024) Msingaphantsi, Mawabo
Imageability, the quality of a place that makes it distinct, recognisable, and memorable, is traditionally considered to make places pleasant and attractive to pedestrians. The use of primarily qualitative (rather than quantitative) descriptions to discuss the concept of imageability poses a challenge for the application of this concept in physical designs in practice, where designers work with environmental features that have specific dimensions and where they must decide how much of each feature (building height, number of courtyards, number of trees etc.) is necessary to make the environment imageable. There is also wide disagreement in urban design theory and practice about what factors contribute to imageability. Quantitative models attempt to address these challenges by producing operational definitions of imageability with strictly defined variables (factors) that are based on the mathematical relationships between physical environmental features (such as building shape or street length) and the occurrence of imageability. The chief benefit of these models for urban design is their potential use as a means to measure and describe the presence of imageability in a given place. However, the drawback of models is the limited number of verification studies to test their applicability in different contexts. The Ewing model is a street-based statistical model that uses a street audit to describe how imageable a place is from the point of view of a pedestrian on a street. The model identifies eight variables that have a statistically significant correlation (R>0.6) with imageability (Ewing, Clemente, Handy, Brownson, & Winston, 2005). In this study I apply the Ewing model to a low-density environment to measure the imageability of part of Diepkloof (Zone 5), a former black township in Johannesburg, South Africa. I use sketches and qualitative descriptions to validate measurements taken on 30 streets. The purpose of the study is to determine the extent to which environmental features such as imageability can explain pedestrian patterns in a neighbourhood. I tested for correlation between pedestrian activity and imageability and then created a linear regression model to predict pedestrian volume on a given street based on the level of imageability on that street. My conceptual framework, however, demonstrated that imageability has three key aspects (structure, identity and meaning) and that different quantitative models have in-built assumptions that privilege one or more of these aspects and may affect how the resultant measurements should be interpreted. I use mapping to illustrate other potential factors of imageability (as described in the literature and in other models) and argue that these represent conceptual gaps in the Ewing model that should be considered when interpreting the model’s outputs and their correlation to pedestrian patterns. The results of applying the Ewing model in Diepkloof Zone 5 show low levels of imageability, which is consistent with my qualitative assessment of the site, as lower densities reduce the potential for composition because the environment has fewer elements. Bivariate linear regression was found to be an inadequate measure of the correlation between imageability and pedestrian activity. These simple linear regression models had R2 values of less than 0.65 and had many outliers, which suggested that there were factors outside of the model that had a significant effect on pedestrian activity. When multiple regression is used to account for other neighbourhood conditions, correlation increased and the R2 value (which describes the models’ predictive capacity). There are three statistically significant variables (with p-values less than 0.05): street length, street integration and imageability

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