Faculty of Engineering and the Built Environment (ETDs)

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A Bridge to Belonging: An Inclusive Living and Day Care Community in Benoni, South Africa for Adults with Autism Spectrum Disorder (ASD)
(University of the Witwatersrand, Johannesburg, 2024) Dias, Jessica Teixeira; Gwebu, Nomonde
Recognising the challenges faced by families of special needs individuals as their children transition into adulthood, this research aims to bridge the gap in services for adults with autism spectrum disorder by establishing tailored support communities that address their unique needs. Furthermore, it seeks to develop a design approach that prioritises the well-being and comfort of individuals with autism, encouraging their sense of belonging. The methodology will include a combination of quantitative and qualitative research methods. The quantitative research will involve questionnaires and a comprehensive desktop review of site analysis, statistics, literature, and precedents. The qualitative research will involve a combination of fieldwork and interviews. Site visits, precedent visits, observations, and photographs will provide firsthand insights into existing facilities and the experiences of individuals with autism. Email communications and semi- structured interviews with various participants will gather diverse perspectives on the topic. The design will take on a holistic approach to supporting its users, which primarily includes the residents, day program participants, and their families. The principal focus of the proposed development will be a learning and therapy centre, complimented by a residential and communal component. Additionally, the development will include a public park and commercial spaces for vocational opportunities. The primary research will delve into the realm of environmental psychology, exploring frameworks such as place attachment and place identity theory, the sense of home, and sensory processing theory. The secondary themes will include prospect and refuge theory, deinstitutionalisation, ergonomics, and sustainable practices. To fully understand the needs of the users, the research will also examine the delivery of services required by the National Healthcare Act for persons with intellectual disability. The proposed architectural style prioritises clarity and simplicity to create a comfortable home-like environment that minimises sensory overload. This approach offers a promising pathway toward promoting social inclusion for individuals with autism. By cultivating community engagement while respecting the need for privacy and moments of solitude, the design aims to create a haven that is both inclusive and supportive.
A Comparative Approach to Market Wide Herding
(University of the Witwatersrand, Johannesburg, 2024) Zwane, Sibongile; Sebehela, Tumellano
This thesis prices, investigates and models market wide herding for selected emerged economies (i.e., U.S. and UK) and named emerging markets (i.e., Taiwan and South Africa) for bonds, equities and real estate sectors. To investigate the mentioned theme/topic, this study develops three hypotheses: (i) the selected indices are prone to market wide herding, (ii) there are systematic volatility patterns during herding process, and finally, (iii) there is positive herding in the real estate sector. The findings are as follows. First, there are persistent herding behaviour of the used indices and moreover, herding behaviour is both within and in between indices. The latter statement is consistent with the findings of Kola (2021). Second, herding exists in volatility towards to the developed economies from emerging markets, irrespective of the product type. Finally, there is definitive herding in the real estate industry, in particular, in indices and not so much in stand-alone REITs. Interestingly, evidence of herding is model sensitive. Finally, the implications are as follows. First, when you invest in bonds, equities and real estate indices, investors should mitigate against herding effects. Second, integration of products, in the context of bonds, equities and real estate, should be encouraged as that increases the levels of information symmetry. The latter statement implies that investing in financial markets would be risky (See; Kola 2021 and Sibongile 2021). Third and finally, intraday investors should have deep insights about emerging markets as emerging financial markets herd towards to emerged markets.
A Comparative Study of the Efficiencies of Vertical Bracing Practices
(University of the Witwatersrand, Johannesburg, 2023-11) Saunders, Shawn Wayne Valintino; Elvin, Alex
The efficiencies of cross sections and configurations applied to vertical bracing are investigated by evaluating reference configurations (RCs), composed of cross braced circular hollow section (CHS) members, against comparative configurations (CCs), consisting of cross-braced Angle members, and single-CHS members. The metrics used to evaluate efficiencies were mass, raw materials costs, and fabrication and erection costs. CCs were found to be more efficient than RCs for most analysed cases, metric and configuration dependent. The following results were found: i. Mass metric a. Crossed-Angle more efficient in 79% of analysed cases. b. Single CHS more efficient in 87% of analysed cases. ii. Raw materials costs metric a. Crossed-Angle more efficient in 92% of analysed cases b. Single CHS more efficient in 88% of analysed cases iii. Fabrication and erection costs metric a. Crossed-Angle more efficient in 90.4% of analysed cases b. Single CHS more efficient in 88.5% of analysed cases Inversions of the efficiency parameter findings, with RCs more efficient than CCs, were observed when: i. RC CHS member slenderness ratios were less than 80-90. ii. CC design loads were greater than 225 kN, 1200 kN and 1500 kN for mass, raw materials and total cost efficiency metrics, respectively
A Conservationist Menagerie: Redefining The Johannesburg Zoo ThroughA Multi-Species Educational Facility
(University of the Witwatersrand, Johannesburg, 2024) Jacob, Anneline
This architectural project seeks to rectify the injustices that the human-wildlife conflict has had on captive, injured and displaced wildlife and their welfare. Throughout the years human have exerted their dominance over wildlife and the current relationship between humans and animals is described as hierarchical and demonstrates a power dynamic whereby humans view themselves as superior to wildlife. This dynamic and the absence of animals which used to be a part of daily life has resulted in a lack of tangible experiences between species resulting in a knowledge gap and poor understanding of animal welfare. This research project will explore the relationship between humans and wildlife in the context of the Johannesburg Zoo which has faced increasing disapproval from the public as its current design fails to provide adequate landscape habitats and ecological aware facilities for animals, thereby decreasing the educational value and overall experience for the animals and visitors, threatening the welfare of the animals. The zoo represents the ideal testing environment due to its possession of animals in stimulated environments. As one of the largest sites that house wildlife within an urban landscape, it facilitates daily human interactions and is the ideal space to observe co-habitation and multi-species relationships. This will facilitate the development of an alternative zoo model which aims to draw lessons from the precedent "Multispecies Design" by Daniel Metcalfe to influence a shift in the power dynamic by creating interactions that will promote respect between humans, wildlife and nature. This will facilitate reconciliation enabling learning so that humans and animals develop a kinship that fosters coexistence and coadaptation to eliminate conflict and captivity, building wildlife welfare and maintaining resources for future use. The research will be directed through an explorative approach that will include a series of photographs, mapping, and research tabulations to gain an understanding of wildlife habitats and how they may be adapted and recreated in the urban landscape. The research will make use of film and comic-like graphics to illustrate the design and spaces representative of a utopian world, which may be created but has not been accomplished yet.
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 decision support framework for grading of civil engineering contractors and evaluation of infrastructure project performance
(University of the Witwatersrand, Johannesburg, 2024) Chiloane-Nwabueze, Salome
The construction sector plays a key role in the economic development of a country. The management of this sector is thus crucial in maximising the performance of the sector and the economy. The South African construction sector performance has some level of inefficiencies that could be improved to enhance the sector’s performance outputs. Therefore, the study aimed to develop a framework for grading civil engineering contractors and the evaluation of project performance. To achieve this, the study reviewed the literature on relevant key concepts and CIDB processes and systems. The government of South Africa has mandated the registration and grading of contractors to the Construction Industry Development Board (CIDB). The CIDB grade is a license for trading with the government. It certifies contractors who are graded as capable of delivering projects up to a pre-determined contract value in each class of work. Currently, the grading system is based on two key determinants, which are the contractor’s track record (i.e., completed projects) and available capital. Presently, a contractor grade does not denote the contractors’ capabilities. However, contractor grading and performance evaluation should be a multi-criteria decision-making process. A questionnaire was developed and distributed to the key participants in the industry to establish whether there is a need for enhancing the current registration, grading, and performance evaluation of contractors in the construction sector and to establish relevant criteria. Of the 149 respondents, the results of the study have revealed that most of the respondents (88.6%) agree that enhancing the current construction sector entry requirements could assist in improving contractors’ capabilities. Moreover, 90.6% of the respondents have indicated that enhancing the current construction sector entry requirements will assist in improving the performance outputs of the construction sector. A multicriteria decision-making methodology using the Analytical Hierarchy Process (AHP) based on seven main criteria with seventeen sub-criteria was carried out for iii grading of contractors and performance evaluation of contractors. Thereafter, using the results obtained from the AHP, an enhanced framework was developed for registering, grading, and evaluating the performance of contractors. Relevant scenarios and CIDB grading scenarios were applied to test and validate the developed framework. The construction sector entry requirements have been proposed by the study based on the literature reviewed and results of the state of practice survey to improve the sector performance. One way of improving the sector’s performance is through entry regulation. Organisations and some countries worldwide have some form of entry regulation to manage the construction sector. To minimise business failure and poor performance, new entrants need to have at least a recognised technical qualification in the aspiring field of work. This will ensure that new entrants have the relevant knowledge of the field in which they aspire to enter. Having entry regulations and improved grading and performance evaluation systems may assist in improving the sector’s performance. Proposals on the enhancements that may be considered by the CIDB are made which may assist in improving the industry’s performance.
A Life Cycle Assessment of Plastic vs Cardboard Packaging in the Fast-Moving Consumer Goods Market
(University of the Witwatersrand, Johannesburg, 2024) Rivett, Stephanie Anne; Harding, Kevin
Globally there is a movement to mitigate the need for single-use plastics as well as the utilization of plastic materials when alternative options are available. This movement comes in response to the extensive research that has demonstrated the long-term negative environmental impact that plastics pose to our existence when disposed of into landfills. A significant contributing factor to the mass of single-use plastics is the packaging industry. This study focused more specifically on the single use plastic packaging in the fast-moving consumer goods (FMCG) market which are used to shrink-wrap bottles together to be supplied into the trade such as Pick ‘n Pay and Checkers. South Africa is facing two main challenges pertaining to the FMCG market: namely the constrained supply of energy and the socio-economic pressure to reduce the environmental impact caused by unrecycled packaging waste. This research aimed to investigate the energy requirements and environmental impact of packaging configurations that included shrink-wrap plastic and cardboard cartons versus packaging configurations that utilized only cardboard cartons to ascertain which option provides the lowest possible energy requirements, and environmental impact. This study aimed to execute a cradle-to-grave life-cycle assessment (LCA) of the two different packaging configurations by utilizing the SimaPro software. The LCA was executed with respect to one reference product that is supplied into the FMCG market year-round known as Prewash Promo. Prewash Promo is a laundry pretreatment that aids in the removal of stains. The first of the two packaging configurations under analysis was the traditional packaging configuration of Prewash Promo that has always been used. This packaging configuration consisted of six bottles that were grouped into two sets of three using rubber bands. The two sets of three were then shrink-wrapped into a group of six. Two shrink-wrapped sixes were then placed into a box that was sealed using plastic packaging tape or sellotape. The second packaging configuration under analysis mitigated the use of shrink wrap plastic and associated materials (elastic bands) thus the second packaging configuration consisted of twelve bottles placed into the box that was then sealed using packaging tape. The main objective of this LCA was to ascertain the packaging material configuration that was the most energy-efficient and environmentally responsible choice to utilize in the Stephanie Anne Rivett A Life Cycle Assessment of Plastic vs Cardboard Packaging in the Fast-Moving Consumer Goods Market iv FMCG market. This LCA was conducted utilizing the data pertaining to the year 2022 and the functional unit of this study was one year’s worth of packaging used in the production of Prewash Promo. Prewash Promo was chosen as the reference product as it does not demonstrate seasonal or geographically specific use, and it was a viable option for the change in packaging configuration. A significant factor that influenced the impact of LCA results was the waste scenarios associated with the use of different materials. In this study, the exact quantities of material that were recycled versus sent to landfills could not be definitively known. It was for this reason that the published industry standard recycling rates for the year 2022 and knowledge of socioeconomic habits were used to formulate assumptions. It was assumed that the minor materials included in the packaging configurations such as packaging tape and elastic bands conformed with social habits and did not exhibit any recycling and went directly to landfill. The recycling rate of corrugated board for the year 2022 was reported to be 61.4% and the recycling rate of plastic for the year 2022 was reported to be 42.8% (Mpact Recycling, 2019a). These recycle rates were utilized to model the packaging configurations to facilitate the comparison between the two. The validity and influence of these assumptions were assessed by means of a sensitivity analysis after the main LCA was executed. The ecoinvent 3 database library available via the SimaPro software (version 9.4.0.3, 2022) and the ReCiPe Midpoint method were used to execute the impact assessment calculations. This method consisted of eighteen impact categories that assessed the impact of each of the packaging materials with respect to the impact they posed to human health, biodiversity, and resource scarcity. The full eighteen category impact assessment was condensed into five focus categories based on the target audience, the research objectives and geographical location of the study. These five focus categories were: global warming, stratospheric ozone depletion, fine particulate matter formation, freshwater ecotoxicity and water consumption. These five categories were chosen because they provide the best overview of the impact in a summarized form pertaining to factors contributing to environmental decline, changing weather conditions, reduction in air quality and the impact of freshwater resources. The LCA was first executed for each packaging configuration in isolation to ascertain the impact contributions of each of the individual factors involved in the construction of the Stephanie Anne Rivett A Life Cycle Assessment of Plastic vs Cardboard Packaging in the Fast-Moving Consumer Goods Market v packaging set-up. The analysis of each packaging configuration in isolation facilitated highlighting major contributing factors to consider replacing with alternatives or mitigating the use thereof. This assessment highlighted the drastic impact contribution that the use of electricity had on the impact score of the heat shrink-wrap plastic configuration. The full LCA comparison was then executed to compare the two packaging configurations. In each of the five focus impact categories the corrugated board only packaging configuration achieved an environmental impact score 83% lower than the heat shrink-wrap plastic packaging configuration. This drastic difference was only reduced to 79.6% when excluding long-term emissions. Upon the conclusion of the LCA comparative assessment the validity of the recycle rate assumptions for corrugated board and shrink-wrap plastic were assessed by executing sensitivity analyses. These analyses determined that the conclusion achieved at the end of the LCA comparison stage remained valid irrespective of the recycling rate of corrugated board or shrink-wrap plastic. The final objective investigated in this study was the uncertainty analysis to assess the accuracy and reliability of the data utilized in the LCA. The uncertainty analysis was executed in the SimaPro software by utilizing a Monté Carlo analysis with the ReCiPe 2016 midpoint (H) method which consisted of 1 000 fixed runs with a confidence interval of 95%. An uncertainty bar chart was generated that displays the error associated with each of the eighteen impact categories. The uncertainty analyses for both packaging configurations determined that the data for global warming, stratospheric ozone depletion, fine particulate matter formation and freshwater ecotoxicity demonstrated low error. The cardboard only configuration exhibited very low error values of between 8% and 61% as opposed to the plastic packaging configuration which exhibited errors between 16% and 214%. The water consumption data in contrast exhibited significant uncertainty for both configurations due to the difficulty in definitively determining accurate water consumption data for such extensive life cycles. Water was utilized extensively in the developmental stages of each of the materials (forestry, paper/pulp manufacturing and plastic polymer and plastic shrink manufacturing) and exhibited significant variation in volume of consumption due to high degrees of variation in plant technology and process equipment age. Stephanie Anne Rivett A Life Cycle Assessment of Plastic vs Cardboard Packaging in the Fast-Moving Consumer Goods Market vi The culmination of the results of each of the assessments executed concluded that the corrugated board only configuration is the packaging configuration that is the most environmentally friendly, and energy-efficient packaging option of the two that were considered.
A linear vibration isolator integrating a non-linear energy sink (nes)
(University of the Witwatersrand, Johannesburg, 2024) Waite, Clinton; Li, Kuinian
This report investigates the integration of traditional linear vibration isolators with non-linear energy sinks (NES) to enhance vibration control in structures subjected to dynamic loading. Structures often respond to dynamic loads—such as machinery vibrations, seismic activity, and environmental factors—by vibrating at their natural frequencies, potentially leading to resonance and structural failure. Vibration isolation and damping systems, such as linear isolators and NES, mitigate these effects. Linear isolators are effective at higher frequencies but have limited performance at lower frequencies, while NES systems offer broader frequency- range effectiveness. This study explores the effectiveness of combining these systems to optimize vibration control. Through simulation of both simple and complex setups, the research compares the vibration response of traditional linear isolators, NES-integrated isolators, and NES systems combined with additional damping elements. Key findings demonstrate that integrating NES with linear isolators significantly reduces peak transmissibility and improves vibration reduction under harmonic and seismic loading. However, the integration's effectiveness varies depending on system configuration and specific loading conditions, highlighting the need for further optimization. The study also presents a parametric analysis for designing vibration control systems tailored to diverse applications, offering valuable insights for engineering practice in reducing structural vibrations.
A Longitudinal Study on the Effect of Patches on Software System Maintainability and Code Coverage
(University of the Witwatersrand, Johannesburg, 2024) Mamba, Ernest Bonginkosi; Levitt, Steve
In the rapidly evolving landscape of software development, ensuring the quality of code patches could potentially improve the overall health and longevity of a software project. The significance of assessing patch quality arises from its pivotal role in the ongoing evolution of software projects. Patches represent the incremental changes made to the code-base, shaping the trajectory of a project’s development. The identification and understanding of factors influencing patch quality could possibly contribute to enhanced software maintainability, reduced technical debt, and ultimately, a more resilient and adaptive code-base. While previous research predominantly concentrates on analysing releases as static entities, this study extends an existing study of patch testing while incorporating an examination of quality from a maintainability point of view, thereby filling a void in patch-to-patch investigations. Over 90, 000 builds spanning 201 software projects written in 17 programming languages are mined from two popular coverage services, Coveralls and Codecov. To quantify maintainability, a variant of the SIG Maintainability Model, a recognised metric designed to assess the maintainability of incremental code changes is employed. Additionally, the Change Risk Anti-Patterns (CRAP) metric is utilised to identify and measure potential risks associated with code modifications. A moderate correlation of 0.4 was observed between maintainability and patch coverage, indicating that patches with higher coverage tend to exhibit improved maintainability. Similarly, a moderate correlation was identified between the CRAP metric and patch coverage, suggesting that higher patch coverage is associated with reduced change risk anti- patterns. In contrast, patch coverage demonstrates no correlation with overall coverage, underscoring the distinctive nature of patches. However, it is noted that relying solely on patch coverage lacks comprehensive overview of coverage patterns. Thus, it is recommended to supplement it with overall system coverage for a more comprehensive understanding. Moreover, patch maintainability also exhibits no correlation with overall coverage, again, highlighting the unique nature of patches. In conclusion, the study offers valuable insights into the nuanced relationships between patch coverage, maintainability, and change risk anti-patterns, contributing to a more refined understanding of software quality in the context of software evolution.
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.
A Process Systems Analysis Towards Hydrogen Pathways Optimisation
(University of the Witwatersrand, Johannesburg, 2024) Kaitano, Caroline; Majozi, Thokozani
Hydrogen is garnering increasing attention as a promising and eco-friendly energy carrier, holding the potential to address global energy and environmental challenges. The emergence of the hydrogen economy is a pivotal technological leap forward in future energy systems. Its central objective is to generate hydrogen primarily from abundant energy sources, thus mitigating our dependence on fossil fuels across industries, businesses, residences, and transportation sectors. At its core, the hydrogen economy encompasses essential facets, including the generation, dissemination, transformation, and retention of hydrogen gas and its diverse applications. Establishing efficient hydrogen production processes represents a critical stride toward the overarching global objective of constructing an economy that revolves around hydrogen as a principal energy carrier, capable of providing a substantial portion of our energy needs and services. The work in this dissertation comprehensively explores hydrogen production pathways by applying a superstructure approach, encompassing various options. A comprehensive database comprising 19 distinct hydrogen production pathways is established in this study. These pathways are subjected to a rigorous analysis, considering availability, environmental sustainability, and economic costs. The overarching goal is to discern the most feasible routes for hydrogen production. The framework devised in this research systematically narrows the initial 19 pathways to a final selection of three, achieving an impressive 84 % reduction in the search space. Among these, the pathway involving steam reforming with carbon capture at 1230 K and 10 bar emerges as the most promising option for hydrogen generation. Having identified the optimal reaction pathway, the focus of the study shifts beyond the framework towards the process design and optimisation of this specific route. After a thorough post-optimisation analysis, it is concluded that the steam reformer operates most favorably under a temperature of 908 K and a pressure of 10 bar. This optimised pathway boasts a remarkable 48 % conversion of methane, underscoring its exceptional environmental and economic advantages. iv This dissertation not only elucidates the systematic framework employed in synthesizing and evaluating the hydrogen pathways superstructure, leading to a significantly reduced search space, but also delves into the intricacies of process design and optimization for the most viable hydrogen production pathway. In doing so, it contributes valuable insights and a structured methodology to the field of hydrogen energy research, offering a blueprint for sustainable and efficient hydrogen production in the pursuit of a cleaner and more sustainable energy future.
A report on the investigation into factors that impact the replication of operational excellence programs across the global operations of a top global mining company: The Case of Rio Tinto
(University of the Witwatersrand, Johannesburg, 2024) Tsomole, Moleboheng; Sunjka, Bernadette
Achieving operational excellence in mining is fraught with challenges, including the lack of standardized procedures, misalignment with company strategy, and cultural disparities across global operations. This study investigates the strategies for efficient deployment of operational excellence programs, with a focus on Rio Tinto’s operational excellence framework, RTSPS (Rio Tinto Safe Production System). A mixed-methods approach was adopted, integrating qualitative data from semi-structured interviews with Rio Tinto managers and employees and an analysis of secondary data from company reports. This study combined deductive and inductive research approaches to provide a comprehensive exploration of operational excellence at Rio Tinto. The deductive approach involved testing specific hypotheses drawn from existing literature on operational excellence programs, such as the assumption that standardized systems like RTSPS would encounter difficulties in culturally diverse environments. Inductive reasoning complemented this by allowing themes and insights to emerge directly from empirical observations during interviews, thus offering an authentic view of the challenges and successes of RTSPS deployment. The qualitative component of the study was centered around 14 semi-structured interviews with key stakeholders across various regions, including operational excellence managers and improvement leads. These interviews were conducted virtually using platforms like Microsoft Teams and Zoom, enabling broad participation across geographically dispersed sites. The interview questions were meticulously crafted using Wengraf’s pyramid model, which starts with Critical Research Questions (CRQs) that are broken down into Theoretical Questions (TQs) and further refined into specific Interview Questions (IQs). This structured approach ensured that the interviews remained focused on uncovering detailed insights into operational challenges and strategic alignment. The questions were adapted to account for the contextual nuances of each participant's operational environment, and particular care was taken to avoid leading questions, thereby minimizing researcher bias.The analysis of data employed thematic coding, revealing key insights into behavioural adaptability, cultural diversity, and the influence of leadership on the adoption of standardized processes. Themes were generated from the qualitative data and cross-referenced with secondary data sources, including integrated annual reports that provided a broader organizational context and corroborated the findings. Secondary data analysis allowed for a deeper understanding of Rio Tinto’s strategic objectives and how these aligned or conflicted with ground-level practices. Using qualitative data from interviews with 14 participants, the research highlights key themes identified through thematic analysis, focusing on the complexities of implementing RTSPS across diverse cultural and operational landscapes. Sentiment analysis conducted via ATLAS.ti software provided additional insights into participants' attitudes and emotional responses, shaping the creation of a comprehensive codebook that guided systematic data analysis. The findings reveal that RTSPS faces significant deployment challenges, including the integration of a standardized system across culturally varied sites, a need for a more people-centric approach, and issues with communication, resource allocation, and adaptability. Participants with experience outside of Rio Tinto provided unique insights into alternative deployment strategies that could enhance replication and adaptability across different industries and operational settings. The study also identifies the foundational elements critical to RTSPS, such as standardized processes, robust training programs, and a centralized knowledge- sharing infrastructure. These components were highlighted as essential for fostering a culture of continuous improvement and ensuring successful replication across Rio Tinto’s operations. Rio Tinto's annual reports from 2018 to 2022 emphasize RTSPS's role in enhancing safety, efficiency, and sustainability, with impacts on the triple bottom line of people, planet, and profit. However, the challenges identified through this research include cultural integration, resource constraints, and the need for local adaptability, mirror broader issues documented in the literature on operational excellence in the 7 mining sector. The study concludes that while RTSPS holds significant potential, its success hinges on balancing standardization with the flexibility to accommodate local conditions and prioritizing employee engagement throughout the deployment process.
A Study of the Effect of Temperature on Cavity Partial Discharges in Polyethylene (PE) Insulation
(University of the Witwatersrand, Johannesburg, 2024) Khangale, Mulovhela Kennedy; Nyamupangedengu, Cuthbert
Synthetic Polymers such as polyethylene are prevalent for high-voltage insulation applications as they offer remarkable insulating and dielectric properties. Notwithstanding precautionary measures made during manufacturing and installation processes, insulation systems are always susceptible to defects for various reasons, which constitute a significant source of Partial Discharge (PD) activity. It is a precursor to insulation degradation leading to premature failure of high-voltage equipment. PD activity is complex due to its non-stationary behaviour and multi- variance dependence. Studies in partial discharge mechanisms have received significant attention over the years to improve phenomena understanding and, in some cases, to allow conclusions to be drawn on the parameters affecting PD mechanisms. These studies have shown that different mechanisms and parameters influence partial discharge activity. In this study , experimental and analytical modelling techniques are used to explore the behaviour of partial discharge mechanisms at varying temperatures. Experimental PD measurements were carried out in accordance with the IEC 60270 standard. A test voltage of 11 kV ac was used. The test temperatures studied were 15C, 40C, 50C, 60C, 70C, 80C and 90C. Test specimens with a cavity diameter of 2.5 mm were assembled using three 1.5 mm thick polyethylene sheets sandwiched between two flat brass electrodes. Partial discharge parameters such as the charge magnitude, inception voltage and PD phase resolved pattern (PDPRP) were measured and analysed at varying temperatures. For analytical modelling, the streamer-like discharge concept is adopted to model PDIV while the apparent charge magnitude is modelled based on the induced charge concept introduced by Pedersen in the 1980s. The curve fitting approach was adopted to replicate and explain the measured experimental data. Results showed that Partial Discharge Inception Voltage (PDIV) increased linearly with temperature for the entire test temperature range. PD charge magnitude initially decreased with temperature from 15°C to 60°C and then increased from 60°C to 90°C. The evolution of PD phase resolved pattern (PDPRP) with temperature was characterised by a turtle-like pattern at ambient temperature, which transitioned into a rabbit ear PDPRP as the temperature increased to 90°C. The findings are interpreted using the mean free path effect on ionisation probability as well as the residual charge dynamics in the cavity as a function of temperature. The overall conclusion is that in polyethylene, cavity discharge characteristics respond to temperature changes. The variations in PD characteristics iv are monotonous for PDIV and non-monotonous for apparent charge magnitude as well as PDPRP. The implications of the findings are that in PD diagnosis,temperature of the equipment under test must be taken into account in interpretation of PD measurements results.
A Symphony of Sakina: Using mosque design to facilitate community development in Mooiplaas
(University of the Witwatersrand, Johannesburg, 2024-02) Jaffer, Raeesah; Janse van Rensburg, Ariane
This research report studies Mooiplaas Informal Settlement in Pretoria, South Africa. The research first discusses the developmental challenges of this marginalised community and then investigates ways in which informal settlements can be developed. It explores the design and application of a Mosque complex, focusing on its potential to facilitate community development. Mooiplaas has a growing Muslim population, and a Mosque is a fundamental requirement to facilitate prayer. The Mosque is further investigated to understand its significance and functionality in community settings throughout history. Previous developmental initiatives undertaken have not reached full potential to holistically address the needs of the Muslim and non-Muslim communities in Mooiplaas. Thus, this research investigates ways the Mooiplaas community can enhance resilience and sustainability by applying the Mosque complex as a fundamental instrument for future development initiatives. The proposed Mosque can facilitate social and economic upliftment within the settlement by providing spiritual development and education and promoting social cohesion.
Acid[c]ity - Undamning the Dam: Wicking of the Harmony Gold Mine Dam Through Algae Exploration
(University of the Witwatersrand, Johannesburg, 2024-02) Le Pere, Justine; Doermann, Kirsten; Daskalakos, Christos
This project discusses the need to help fight against the effects of mining on water, and to help the surrounding environment and community. A large emphasis is placed on the use of algae to treat the water from the Harmony Gold Mines’ tailings dams, and the facility plays host to this natural water treatment method. The facility provides the space for water resource management and water treatment education to take place. The community of Tshepisong Phase 2 lies north of the facility and acts as the activator of the facility. Without the community needing to collect water for use at home, the facility would not have a strong sense of integration into the township. The layout of the facility allows the layers of privacy to help aid the program, and the program allows the facility to be transparent to its visitors and the neighbouring township.
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.
Addressing high dimensionality in water quality modelling in water distribution networks
(University of the Witwatersrand, Johannesburg, 2024-02) Machweu, Morongwa Ednah; Taigbenu, Akpofure
Water quality models are the most effective tools for characterizing water quality conditions, assessing the effects of water pollution, and supporting decision-makers with water quality management. They can be utilised for detecting the variations in the water quality parameters. Despite the usefulness of water quality models, an appropriate and simple water quality descriptor for a particular application, considering the high dimensionality of various water quality parameters, remains a challenge (Chapman, 1992). To address this high dimensionality, a single dimensionless index is commonly used to describe water quality for a particular application. While pollution loads at various points in a river reach have been widely assessed by studies using water quality indices, little research has been done on water distribution networks with service reservoirs and a variation of loading conditions. In a water distribution network, service reservoirs function similarly to rivers in that they have complicated mixing mechanisms, are subject to a variety of water quality factors, and are sized and located differently. The most common water quality indices require the formation of subindices and weights to avoid ambiguity, eclipsing and rigidity. The Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) does not require the formation of sub-indices and weights, thus providing a simplified way of describing water quality. This study investigates the use of the CCME WQI to address high dimensionality in water quality modelling of water distribution networks, taking into consideration the locations of multiple service reservoirs. This study was carried out primarily for decision-making and design optimization purposes only. Using EPANET 2.2, four hydraulically optimised solutions (which satisfied minimum pressure requirements) were further analysed for water quality performance. This was achieved by incorporating simulated data on three water quality variables (chlorine residual, water age and THM concentration) into the CCME WQI for a hypothetical water distribution network, Anytown. The results indicate that two of the four hydraulically optimised solutions achieved excellent water quality levels. This study has demonstrated the usefulness of a dimensionless index as a proxy for multiple water quality variables of a water distribution system in facilitating decision-making.
Aerodynamic Force Variation on a Trailing MotoGP Motorcycle in a Corner
(University of the Witwatersrand, Johannesburg, 2024) Shaw, Craig Byrne; Boer, Michael
Motorcycle racing is a popular form of motor racing. The MotoGP category produces exciting and competitive races due to motorcycles following each other so closely. This has led to significant aerodynamic advancements being made in the MotoGP category over the past decade. Motorcycles and riders often race within the wake of a leading motorcycle as a result of this competitive racing. Racing in the wake provides an advantage on a straight due to the reduced drag force. This allows for greater acceleration and an opportunity to overtake the leading motorcycle. The effect of the wake on a trailing motorcycle in a corner has not been explored in depth. This research was focused on the aerodynamic force variation on a trailing motorcycle in the wake of leading motorcycle. The optimal position for the trailing motorcycle to gain an advantage over the leading motorcycle was determined subsequently. This was achieved using Computational Fluid Dynamics (CFD). The geometry of the motorcycle was obtained using 3D scans of a 1/18th scale model 2018 Repsol Honda RC213V. The geometry of the rider was drawn using CAD. Initial CFD models were created simulating the motorcycle and rider in a straight line to compare to existing published data for validation. The CFD cornering methodology was developed by Queens University in association with Siemens. The method makes use of rotating reference frames. This simulates the motorcycle and rider cornering at a constant velocity around a constant radius corner. Models were created for a singular motorcycle and rider at varying lean angles between 40 and 60 degrees with matched velocities and corner radii. The aerodynamic forces of drag, lift and side force were analysed on the motorcycle and rider for each case. The trends for these forces were determined relative to the changing lean angles. The drag on the motorcycle and rider increased non-linearly as the lean angle increased with the side force following a similar trend. The lift on the motorcycle and rider also increased non-linearly as the lean angle increased. These same CFD models were recreated with a second motorcycle and rider following a leading motorcycle to determine the effect the wake had on the aerodynamic forces. The second motorcycle and rider were positioned 1 characteristic length behind the leading pair on the same racing line. The drag on the trailing motorcycle and rider decreased as the lean angle increased. The lift on the trailing motorcycle and rider followed a similar trend to the leading pair with it increasing as the lean angle increased and the side force fluctuates as the lean angle increased. This resulted in the trailing motorcycle having a negative allowable change in forward acceleration relative to the leading motorcycle at lean angles lower than 60 degrees. The optimal position for a trailing motorcycle in a corner was determined by positioning the motorcycle and rider on various racing lines and following distances behind the leading motorcycle and rider. This created a grid pattern of the tested trailing positions. Two smaller racing line radii, three larger racing line radii and three different following distances were tested. The optimal trailing position at a 50 degree lean angle was found to be 1 characteristic length behind and on a racing line 1 characteristic width larger than the leading motorcycle. This position resulted in a positive allowable change in forward acceleration relative to the leading motorcycle around a corner radius of 125.86 m at 38.36 m/s. This iii position was tested around another two corner radii of 75 m and 150 m. This resulted in a negative allowable change in forward acceleration of around the 75 m radius corner and a greatly improved positive change in forward acceleration around the 150 m radius corner. From these results it was concluded that this optimal position is only viable around larger radius corners. It was approximated that this optimal position provides the trailing motorcycle an advantage around corner with radii larger than 86.8 m.
Alternative Energy Generation in Public Health Facilities (Hospitals): An analysis of the coal-fired to the natural gas-fired central generating system
(University of the Witwatersrand, Johannesburg, 2024) Nsimbini, Ngcebo
Coal boilers have historically been a significant source of energy generation in industries. However, their use is associated with substantial environmental impacts that are increasingly untenable in the context of climate change. This research examines the challenges and opportunities associated with transitioning from coal-fired to natural gas-fired central generating systems at Helen Joseph Hospital. The researcher chose to focus on natural gas because it is a cleaner and more efficient alternative to coal, making it a viable transitional energy source for decarbonisation in hospital central generating systems. Natural gas functions as a transitional or “bridge” fuel in the global energy landscape. Its relatively lower carbon intensity compared to coal positions it as an intermediate solution that facilitates a gradual shift toward renewable energy sources. This role is critical in mitigating greenhouse gas emissions in the short to medium term, thereby contributing to environmental sustainability and the reduction of public health risks associated with air pollution. The research looks at the low adoption of alternative energy sources in these systems despite their critical role in supporting essential functions such as heating, ventilation, sterilisation, water, and heating. By focusing on energy transition and decarbonisation, the study aims to identify barriers to adoption and propose strategies for implementing more sustainable energy solutions within healthcare facilities, which are among the highest energy consumers in the built environment and are categorised as part of the commercial sector. Focusing on energy transition and decarbonisation, this study employs a case study approach centred on the Helen Joseph Hospital central generating system. Primary data was gathered through 15 in-depth interviews with purposefully selected key informants. The research methodology used qualitative approaches. The interview data were thematically coded and analysed to address the research questions effectively. The findings stress the importance of a multi-faceted, collaborative approach to improve the transition from coal-fired boilers to gas-fired systems in hospitals, with a strong emphasis on minimizing environmental impacts. The study highlights that calculating an organisation's carbon footprint, including emissions from boiler operations, can pinpoint opportunities for energy transition and emissions reduction. Additionally, this approach allows for progress tracking over time and contributes to achieving broader sustainability goals.
Alternative Tenure Options as a Stepping Stone for Urban Land Reform: The Case of Kwa Mai Mai Muthi Market
(University of the Witwatersrand, Johannesburg, 2024-02) Mnguni, Thobeka; Maina, Miriam M.
This research uses qualitative methods to investigate the case of the Kwa Mai Mai muthi market located in the central business district of Johannesburg where over the decades informal traders have converted their trading units into residential homes. This case is used to respond to the research question, ‘To what extent is taking administrative action to improve land tenure by offering communities rights to occupy urban land feasible and necessary for advancing the urban land reform agenda?.’ The research acknowledges that popular approaches to improving tenure by converting insecure tenure rights to statutory ownership through the Deeds office has had limited success and resulted in efficiencies due to the high costs and the resources intensive nature of this approach. Instead, the research recommends a necessary transition to improving tenure in innovative, context-specific ways that work to build on existing settlements through taking low-cost and low LOE administrative action.