4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item Low-temperature electronic transport of metal doped carbon nanotube molecular hybrids and Nitrogen-doped nanocrystalline diamond(University of the Witwatersrand, Johannesburg, 2024-08) Sodisetti, Venkateswara Rao; Bhattacharyya, SomnathThis thesis explores the magnetism and spin-related properties in carbon-based molecular hybrid materials, with a focus on expanding our understanding of low-dimensional carbon structures and their potential electronic applications. The investigation spans from one-dimensional systems, such as carbon nanotubes (CNTs) functionalized with single-molecule magnets (SMMs), to three-dimensional systems like nitrogen-doped ultra nanocrystalline diamond (UNCD). In these carbon structures, electronic transport is intricately tied to microstructural features, such as grain boundaries and impurity clusters, which hold significant potential for the development of all-carbon electronic devices. The research begins with a detailed examination of the chemical functionalization of multi-walled carbon nanotubes (MWCNTs) through controlled acid treatment to achieve precise metal doping. Using Raman spectroscopy and complementary techniques like ICP-MS and ToF-SIMS, we successfully demonstrate how functionalization levels influence the magnetic properties of CNT hybrids loaded with magnetic metals from the lanthanide series (Gd, Tb, Dy). The study reveals that low percentages of metal doping (0.5% to 1.0%) preserve the magnetic bistability of SMMs post-grafting, while higher doping levels lead to complex magnetic behaviors including super paramagnetism, quasi-ferromagnetism, and potential Kondo lattice behavior inCNT-heavy metal systems. We also explore the spin-phonon coupling in Gd-filled double-walled CNTs, where the onset of superparamagnetic properties at low temperatures is coupled with phonon mode stiffening observed via Raman spectroscopy. This enhanced coupling offers promising pathways for developing efficient molecular qubits through the modulation of spin-phonon interactions in one-dimensional systems. The second part of the thesis investigates into the microwave plasma-assisted chemical vapor deposition (MWCVD) growth of nitrogen-doped nanocrystalline diamond (NCD) thin films on different substrates. By pioneering upgrades to the MWCVD system, I was able to achieve reliable growth of high-quality nanocrystalline diamond thin films. Notably, I observed a novel nanostructure, termed Diaphite-a previously unreported feature, in these NCD films, consisting of nanodiamond grains coherently linked with graphene-like rings. This structure, along with the non-equilibrium growth conditions induced by nitrogen doping and secondary nucleation, presents unique polymorphic features in artificially grown diamonds. Detailed low-temperature transport measurements on four different samples—ranging from 7.5% to 20% nitrogen doping—uncovered complex transport phenomena such as 3D weak localization (WL), variable-range hopping (VRH), and unusual magnetoresistance (MR) behavior. In particular, the 7.5% N2-doped UNCD film on quartz exhibited 3D weak localization (WL) at low fields and anti-weak localization (AWL) at higher fields, with distinct magnetoresistance characteristics depending on the direction of the applied magnetic field. The 20% N2-doped films on both quartz and silicon showed more metallic-like behavior, with magneto-resistance characterized by a B1/2 dependence at low temperatures, suggesting an intricate relationship between doping level, microstructure, and electron transport. These findings significantly expand our understanding of the role that microstructural and chemical modifications play in determining the electronic and magnetic properties of carbon-based materials. This work provides a foundational platform for future research into carbon electronics, offering potential breakthroughs in spintronics, molecular transistors, quantum computing, and other advanced electronic applications.Item A practical review of the effectiveness of artificial intelligence in the automated review of legal contracts(University of the Witwatersrand, Johannesburg, 2024) Fouché, Jacques GerritThis research report compares the performance of AI-driven automated contract review platforms with that of human contract reviewers, aiming to see improved effectiveness for the elements of time, cost and quality. An empirical study is done by comparing the specific performance of an automated contract review platform provider, Lawgeex, to the human contract reviewers of a business entity, Endress+Hauser. The results of the effectiveness assessment are reported on through dashboard data and questionnaires to the users of the platform. Recommendations are made both in general and specific to the two entities of the empirical study.Item Mobile banking apps curation: Assessing the factors that influence mobile banking’s continuous use amongst Millennials and Generation Z(University of the Witwatersrand, Johannesburg, 2024) Mashishi, Neo; Zulu, MelissaThe proliferation of mobile banking platforms and the widespread use of intelligent devices like smartphones and tablets have caused a paradigm change in the banking industry in recent times. Millennials and Generation Z (Gen Z), dubbed the "digital natives," make up most of these service consumers. Millennials and Gen Z are increasingly using mobile banking apps, which has transformed how financial services are delivered. Nevertheless, despite being widely adopted, banks need help to ensure the continuous use of these apps to sustain a devoted and loyal consumer base while competing in the market. This study, therefore, investigates the factors influencing Millennials and Gen Z's continuous use of mobile banking applications. Five theoretical frameworks have been adopted to direct the research inquiry: Computers As A Social Actor (CASA), Expectation Confirmation Theory (ECT-IS), Social Response Theory (SRT), Task Technology Fit (TTF), and the Unified Theory of Acceptance and Use of Technology (UTAUT). The study adopted these frameworks based on their theoretical and empirical applicability and ability to provide perspectives into the variables impacting Millennials and Gen Z's continuous use of mobile banking apps. The study employed SPSS (Statistical Package for the Social Sciences) for the analysis of descriptive statistics. To validate the theoretical model and investigate the interactions between variables, Partial Least Squares Structural Equation Modelling (PLS-SEM). PLS-SEM, Smart PLS software was used to assess the validity and reliability of the constructs as well as the strength and importance of the proposed paths in the structural model was made possible by the PLS-SEM methodology. This provided an overview of the dataset and made it possible to do a thorough analysis by outlining important features like means, frequencies, and standard deviations. The research used quota sampling for a sample size of 505 participants. The study's conclusions indicate that there is a substantial correlation among perceived anthropomorphism, expectation confirmation, service quality of mobile applications, mobile banking app satisfaction, technology fit, and consistent usage of mobile banking apps. The study’s goal is to advance our understanding of the field of banking and financial services marketing. The banking sector can apply the findings and insights to differentiate its offerings from its competitors and gain a competitive edge while potentially boosting profitability.Item Digital toolbox for the generation and detection of vectorial structured light(University of the Witwatersrand, Johannesburg, 2023-06) Singh, Keshaan; Dudley, Angela; Forbes, AndrewLight has been an invaluable tool in the development of the modern world, with the myriad of applications increasing along with our degree of control over it. From the development of coherent light sources, to the shaping of amplitude and phase, this development has not ceased for the past half century. The field of structured light, borne out of the necessity and desire for control over light, has been growing steadily in recent years. In the spatial domain, the control over light’s polarization (i.e., the local planes in which the electric and magnetic fields oscillate) has been the most recent avenue of improvement, providing enhancements to a variety of applications ranging form microscopy and communication to materials processing and metrology. This class of light, commonly referred to as vectorial light, often requires specialised equipment in order for its its creation before its numerous benefits can be exploited. These tools often incur high costs and suffer from limitations relating to the diversity of vectorial light they can create, wavelength dependence and slow refresh rates. This thesis follows the development of a series of digital tools for the versatile generation and analysis of vectorial light using low-cost core technologies which can operate at high rates over a broad wavelength range. We follow the development of the generation tool in the context of its application in generating novel accelerating polarization structures, emulating vectorially apertured optics, generating probes to measure birefringence and chirality and creating synthetic spin dynamics. The development of the analysis tool is explored by investigating its application in performing automated digital Stokes polarimetry measurements, completely characterizing the internal degrees of freedom of arbitrary vectorial light and acting as a polarization and wavelength independent wavefront sensor. We then demonstrate how these tools can be used, in conjunction, to investigate the fundamental invariance of vectorial light to perturbing channels and how this invariance can be exploited in a highly robust novel communication scheme. In addition to demonstrating the applicability and versatility of these vectorial light tools, the applications offered a means to highlight areas for the optimization for the design. This culminated in the ongoing prototyping of versatile, fast, broadband devices which operate stably and have a small physical footprint.Item Can emoji constitute defamatory content in the context of the South African law of defamation?(University of the Witwatersrand, Johannesburg, 2024) Saloojee, RaeesaThe use of emoji in digital communication often reflects a casual and carefree approach to conveying emotions and sentiments. Frequently added alongside text messages, emoji are seen as harmless embellishments, requiring little thought regarding their meaning or potential consequences. However, these seemingly innocuous additions may carry significant legal implications. Some emoji have acquired secondary meanings and connotations, which may give rise to defamation claims. This research report thus delves into the intersection of defamation law and emoji. Specifically, we examine the potential for emoji to constitute defamatory elements and explore how courts may interpret their usage. Drawing on legal perspectives from the United Kingdom and Australia, this research report sheds light on the evolving challenges posed by emoji in the realm of defamation law. As South African jurisprudence has yet to grapple with the defamatory potential of emoji, this research report explores whether South African courts will follow the lead of their international counterparts in interpreting emoji. This study thus contributes to the evolving discourse on the intersection of technology, communication, and the law in the digital age.Item 3D Human pose estimation using geometric self-supervision with temporal methods(University of the Witwatersrand, Johannesburg, 2024-09) Bau, Nandi; Klein, RichardThis dissertation explores the enhancement of 3D human pose estimation (HPE) through self-supervised learning methods that reduce reliance on heavily annotated datasets. Recognising the limitations of data acquired in controlled lab settings, the research investigates the potential of geometric self-supervision combined with temporal information to improve model performance in real-world scenarios. A Temporal Dilated Convolutional Network (TDCN) model, employing Kalman filter post-processing, is proposed and evaluated on both ground-truth and in-the-wild data from the Human3.6M dataset. The results demonstrate a competitive Mean Per Joint Position Error (MPJPE) of 62.09mm on unseen data, indicating a promising direction for self-supervised learning in 3D HPE and suggesting a viable pathway towards reducing the gap with fully supervised methods. This study underscores the value of self-supervised temporal dynamics in advancing pose estimation techniques, potentially making them more accessible and broadly applicable in real-world applications.Item Factors Affecting Blockchain Technology Adoption by Organizations in the Livestock Supply Chain Industry in Zimbabwe(University of the Witwatersrand, Johannesburg, 2024) Tambudze, Pelagia; Isabirye, NaomiBlockchain is a distributed ledger technology that provides the building block for many innovations. The distributed nature of blockchain, its immutability, and anonymity enable trust, transparency, and security among transacting or trading partners. The accelerated unfolding of 4IR due to the COVID- 19 pandemic recently unveiled several critical gaps within global supply chains, including livestock supply chains. The main challenges faced by organizations in the livestock supply industry in the developing world include difficulties for farmers in accessing new markets, no flexibility in production times, and no traceability for the consumer market to trace food component authenticity. In Zimbabwe, livestock is an important sector contributing about 22% of the total GDP. From several studies done by other researchers in different industries, such as health care, banking, mining, education, and agriculture, it is evident that blockchain technology solves most of these issues by decreasing data asymmetries and the cost of transactions to benefit all stakeholders. Blockchain-based solutions have recently been introduced to the livestock sector, and Zimbabwe is one of the early adopters among its African counterparts. However, the adoption rate by organizations within the livestock supply chain has been minimal. Using the lens of the TOE framework, this study investigated the factors that affect the decision by organizations in Zimbabwe's livestock supply chains to adopt blockchain technology. A qualitative approach was applied, interviewing fifteen informants from various levels of the livestock supply chain. Responses were analysed using thematic analysis. The study found that adopting blockchain benefits organizations and the overall livestock supply chain. The study found that technological, organizational, and environmental factors influenced organizations' decision to adopt blockchain technologies within livestock supply chains. These factors included availability of the technology, cost of the technology, skills availability, regulation and policies, competitive pressures, presence of blockchain providers, political and socio- economic factors and market trends.Item Universal internet access in South African disadvantaged communities: is there adequate regulation?(University of the Witwatersrand, Johannesburg, 2024) Thomas, KhayakaziAs a result of the advent of the fourth industrial revolution, artificial intelligence, the technology of things and other similar technologies, information communications technologies (ICT) form the basis of our routine lives and sit at the core of both economic and social development. Therefore, the advancement of universal access and service is indispensable for the equal and full enjoyment of all freedoms and rights by all and provides for the improvement of the quality of life for all citizens, and further presents a gateway to freeing each person's potential, as envisaged in the Constitution. This is particularly true for the digitally marginalised situated in informal settlements, townships and remote rural areas (Disadvantaged Communities). Notwithstanding the above, statistics show that to date the digital community in South Africa is still very much skewed towards the affluent urban communities, with only 1% of rural households able to access the internet in their homes. Achieving universal access and service in Disadvantaged Communities is a key policy goal in a democratic society such as ours. It is in light of this that this research report presents a multi-method research approach to holistically conclude on the adequacy of the South African regulatory framework to drive the advancement of universal access and service in Disadvantaged Communities, and recommend law reform. This entails a review of the regulatory framework governing universal access and service (in the South African historical background context under the apartheid regime) compared against international best practices on the regulation of universal access and service in Disadvantaged Communities (using the prevailing socio-economic realities in Disadvantaged Communities as guiding principles). The research report findings, taking into consideration the South African historical background and the prevailing socio-economic realities in Disadvantaged Communities, indicate that the South African regulatory framework is to a great extent on par with international best practices on regulation aimed at the advancement of universal access and service in Disadvantaged Communities, barring its unsuccessful implementation. The research report identifies that the unsuccessful implementation of the regulatory framework is largely owing to its fragmentation (i.e., the regulatory framework relies on vast legislation, policies and regulations and different stakeholders for its implementation). Therefore, the proposed law reform constitute regulatory framework structural measures aimed at redressing the identified fragmentation so as to achieve a regulatory framework that adequately facilitates the implementation of the universal access and service objective in Disadvantaged Communities..Item Embracing technology to rejuvenate South African mining: a comparative case study analysis of a South African and an Australian mining firm(University of the Witwatersrand, Johannesburg, 2024) Vink, Tarryn; Callaghan, ChrisIt is well recognised that the mining industry is the historic bedrock of the South African economy. However, since 2000 the industry has shown signs of decline that include, inter alia, a slowdown in growth along with productivity issues. Since South Africa (SA) lags behind its global competitors in terms of technological innovation and implementation; many leaders in the mining industry are of the view that the increased use of technology will arrest this decline and restore the mining industry to a stronger position in the South African economy. What is, however, not fully understood is the extent to which technological change is contextually path dependent. This meaning that technological change in an industry is restricted by past events which enhance its resistance to change. This results in a lack of knowledge regarding how best to manage technological change. This would include understanding the most suitable implementation methods for certain contexts. The intention of this dissertation is to explain why firms in the South African mining industry lag behind their global competitors in terms of technological adoption. It aims to understand how differing contextual factors influence mining firms’ behavior, that, in turn, has an industry- level effect. It aims to understand how firms should manage this technology properly to optimise its interaction with its environment. Additionally, it aims to understand which theoretical approach, in relation to technological change, mining firms should follow to properly navigate their technological trajectories in light of contextual imperatives. The unit of analysis in this methodology is at the firm level. It takes specific contextual factors into account to determine which method of implementation is more appropriate for new technological advancements. This was executed by conducting two methodology phases. Phase 1 of the methodology which consisted of a holistic comparative case study analysis of a South African and an Australian mining firm. This study phase analysed archival documents that tracked changes in the responses of these mining firms over time. This was conducted using information from their financial statements and company reports, with the aim of investigating how these matched the government and environmental contexts seen in policy and country related documents. Phase 2 of the methodology comprised a qualitative analysis that used individual interviews in an attempt to develop useful insights that contextualise and support the findings of Phase 1. Various theoretical predictions have been derived in the form of propositions. The theory thus inductively developed has been used to answer some how and iii why questions about the strategic responses of firms to contextual imperatives. The study therefore produced a holistic analysis illustrating how each firm engaged with its respective contexts and how this may have resulted in path dependant relationships regarding technological innovation. The research emphasises that the South African mining industry's lag in technological adoption compared to global competitors could be attributed to an imbalanced innovation focus and a restrictive business context. It suggests that firms should address their technological and contextual needs separately to effectively manage innovation. The findings also stress that incremental improvements alone, are unlikely to enable a catch-up up with global leaders. Instead, radical interventions are necessary to shift the current trajectory toward one that prioritises productivity to achieve social objectives, enabling a plausible catch up.Item Understanding the transformation of knowledge-building during online lessons: An analysis of online teaching material related to Grade 12 Financial Mathematics using Legitimation Code Theory(University of the Witwatersrand, Johannesburg, 2024) Naidoo, Anashree; du Plessis, JacquesEducation institutions in South Africa and around the world had to close their doors during the lock down in response to Covid-19. As a result of this, many educational institutions proactively engaged in remote teaching to promote a culture of teaching and learning even though learners were not in a physical classroom space. This study aims to comprehend the formation and variation of cumulative knowledge that may occur during distance teaching. To accomplish this, a series of online lessons on the topic of annuities is analysed focusing exclusively on semantic density dimension of Legitimation Code Theory (LCT). LCT is a sociological framework developed by professors Karl Maton and Susan Hood. It aims to understand and analyse the ways in which knowledge is legitimized within different social fields, such as education. Semantic Density within LCT refers to one of the key dimensions used to analyse knowledge practices. It focuses on the degree of complexity and abstractness in the language and symbols used to convey knowledge within a particular field. The online teacher (presenter) focuses on annuities in financial mathematics through six lessons where the knowledge is revised and applied in different contexts. This study focused on the analysis of the online lesson transcripts, using a translation device that focuses on the semantic density of the series of six open-source online revision sessions. The outcome of the analysis is plotted in a graphical representation that visually describes the cumulative knowledge building during each lesson. The semantic profiles for each video of the online lessons illustrates the transformation of cumulative knowledge building that has been achieved. The analysis of the online lessons using semantic density have further indicated that the complexity of lessons does not necessarily decrease or limit the understanding of the pedagogy, in this case, financial mathematics. The examples in the online videos moved from simple to complex and demonstrated a link from one example to the next example.