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Numerical modelling of power law constants established through impression and micro-Uniaxial creep methods for service exposed A234WPB steel
Get PDFContinuous monitoring of creep life in materials operating at high temperatures and pressures is imperative to prevent catastrophic failures and ensure timely replacement of worn-out components in industrial plants. Small-scale creep testing methodologies offer a valuable means of assessing material creep life while preserving structural integrity. Motivated by the need for reliable methods in creep life assessment, this study aimed to investigate the creep properties of A234WPB material subjected to service conditions using Impression creep and micro-uniaxial creep testing techniques. The research questions focused on establishing power law constants through small-scale creep testing, validating these constants using numerical modelling, and assessing their practical implementation in predicting material creep life. Samples extracted from service-exposed A234WPB steel alloy underwent step-load impression creep tests and step-temperature micro-uniaxial creep tests to derive the power law creep equation. The determined stress exponent of 3.967 indicated that dislocation creep was the dominant creep-controlling mechanism at 520 °C. A numerical model, utilizing the established power law constants, demonstrated a strong correlation with experimental findings in steady-state creep rates. Furthermore, the conventional Monkman-Grant approach was employed to predict the remaining life of the service-exposed material using impression creep data. The predicted remaining life aligned with the scatter band of uniaxial rupture life on a Larson-Miller plot, highlighting the practical utility of impression creep and micro-uniaxial creep testing techniques in assessing creep life. This study contributes to the advancement of small-scale creep testing methods and underscores their potential for practical implementation in industrial settings, thereby enhancing the reliability and safety of high-temperature and high-pressure operations.Thesis (MEng) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 202
The influence of interpretation of iso 19011: 2018 guidelines on performing third-party quality audits to promote uniformity and consistency in the audit process
Get PDFThird-party quality audits (TPQA) facilitate performance improvement and reliability that give confidence to organisations concerning the process quality of services and products. In South Africa, ISO 9001: 2015 standard certification gained popularity as a requirement in the business tender criteria. While TPQA are crucial for evaluating conformance to industry standards, reportedly numerous organisations share disappointments as their expectations seem no longer realised. Certification faces criticism about its effectiveness in delivering TPQA that add value. Research has shown in some cases that despite the revisions of the ISO 19011: 2011 standard and limited studies conducted TPQA are regarded as added cost activities, and their initial purpose as an impartial tool to ensure quality of deliverables is no longer upheld. Increasingly, because of inconsistencies and unethical practices often observed in the industry, organisations question the significance of TPQA. Hence, the need was identified to determine and explain the influence of the ISO 19011: 2018 standard interpretation on the application of the audit guidelines in performing TPQA, to promote consistency in the audit process. A sequential exploratory mixed-method study was conducted employing a document analysis of the ISO 19011: 2018 standard, semi-structured interviews with the certification managers (CBs) and third-party quality auditors; and a survey questionnaire which was sent to quality practitioners and experts. The findings of the qualitative phases of the study were verified during the quantitative phase. The outcome of each phase of the study informed the development of the data collection instrument in the next phase. Two frameworks were designed: A conceptual framework after the document analysis and an empirical framework based on the interview data. The qualitative findings and quantitative results were integrated before conclusions were drawn and recommendations made. Achieving effective audits requires that an audit programme be established, implemented, monitored, reviewed and improved within the confines of the principles of auditing. The study found that the value of the audit process is limited by the different interpretations of the audit guidelines held by CBs and auditors. Adherence to the principles of auditing particularly, integrity and independence were found as the core of the audit process while their disregard reflected failure of the real intent of auditing. In managing the audit programme the study revealed that the inconsistencies in the audit procedures and documents developed for the auditors were ascribed to some CBs’ personal interpretations. Potential pitfalls are exacerbated by most auditors being contracted across the different bodies, and work according to the different CBs’ processes. The different interpretations of the standard suggest that certain guidelines might be vaguely written, resulting in uncertainties concerning reproducibility of the audit process. Competence featured most so that lack of it was perceived as the main hindrance to the audit process. The study recommends formal consultations among experts and practitioners to reflect on the interpretation of the guidelines to manage the audit programmes, and eliminate root causes and practices affecting the audit process. Also recommended is integration of the study findings into auditor training courses to support standardisation and reduce the variations across and amongst the different CBs and auditors.Thesis (PhD) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 202
Exploring senior phase teachers’ use of Kahoot! Gamification as a formative assessment tool to scaffold mathematical understanding
Get PDFIn South Africa, digital technology, particularly gamification, continues to become an important teaching and learning tool. Its importance lies in scaffolding mathematical understanding, improving the quality of assessment, and developing twenty-first-century technological skills for effective mathematics assessment. To explore this importance, senior phase mathematics teachers are encouraged to adopt gamification technology such as Kahoot! in assessment. The study adopted a case study research design with a interpretivist research paradigm, as this method allows detailed exploration and understanding of a specific context through a close connection with the participants. Data was collected using semi-structured questionnaires, focus group interviews, non-participant observations, and reflective journals. The research involved ten purposively selected senior-phase mathematics teachers from two schools in the Sarah Baartman District, Eastern Cape Province, South Africa. The study drew upon Vygoysky's Sociocultural Theory for its theoretical framework, while the Technological, Pedagogical, and Content Knowledge was used for analysis. The data analysis pursued an inductive approach. Adopting a thematic analysis included coding participant responses, organizing codes into concepts and categories, and developing a theoretical framework from the resultant categories. A four-phase process was involved: coding, conceptualizing, categorizing, and theorizing, was employed. This process and using NVivo software for data organization and management helped identify patterns, themes, and significant concerns surrounding the study's core subject. The findings from the study were as follows: Firstly, it was revealed that most teachers have a positive perception and attitude towards using Kahoot! for formative assessment, believing that it enhances teaching and learning quality. However, they showed scepticism due to insufficient Information and Communication Technologies knowledge and training. Second, teachers' pedagogical and technological experiences were predominantly enjoyable. Kahoot! was accepted as beneficial for promoting collaboration, interaction, and immediate feedback. Third, the study identified enabling and constraining factors in using Kahoot! for formative assessment. The enabling factors include Kahoot!, which was convenient and accessible, promoted immediate feedback and fostered collaboration and interaction. The constraining factors include Information and Communication Technologies and network interference, which posed limitations. The research concluded that Kahoot! as a platform for formative assessment indeed scaffold mathematical understanding. The study recommends increasing teachers' access to educational technology, incorporating continuous professional development programs, providing subject-specific training, and encouraging teachers to adapt to emerging technologies. The study also provided recommendations for future research to explore learner perceptions, employ a mixed methods approach to help quantify learner performance and investigate the pedagogical and technological experiences of senior phase mathematics teachers regarding formative assessment.Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 202
Guidelines towards the use of virtual consultation in primary healthcare
Get PDFIn an environment of expanding demand on the healthcare system to provide equitable, accessible, and safe healthcare, the use of information and communication technology (ICT) is one of the strategies identified to fulfil such expectations. To make this achievable, ICTs are integrated in healthcare using telehealth, which permits the provision of remote healthcare by using virtual health technologies. One domain of telehealth which permits remote care is virtual consultations. It is an important tool in the healthcare industry used to promote access to healthcare services, especially for elderly people or people with disabilities, those suffering from chronic diseases such as cardiovascular disease, diabetes, and hypertension, among others, and for people in rural and underserved communities. This is possible using videoconferencing technology, telephone consultations, email, or instant messaging. Virtual consultations are becoming an integral part of the healthcare industry all over the world, and it is important to understand how to make use of them to promote healthcare access. The purpose of this study was to create guidelines to assist primary health care professionals in the most effective ways of using virtual consultations to improve access to essential health care services. As such, the objectives governing this study were to identify the role that virtual consultations play in healthcare, to investigate the factors that impact the use of virtual consultations, to review the existing guidelines on virtual consultations, as well as to identify the requirements needed for virtual consultations. This research followed several aspects to guide the methodology of this study. The research process governing this research was the design science research process. The research made use of literature reviews, argumentation, and a survey for data collection as well as a qualitative content analysis to analyse the data. The data collection consisted of 32 survey responses, which aided in the identification of the factors impacting the use of virtual consultations. The results showed that virtual consultations are utilised for various aspects of care delivery, but face-to-face consultations are still the first choice of consultation.Thesis (MIT) -- Faculty of Engineering, the Built Environment and Technology, School of Information Technology, 202
A cyber security strategy to mitigate cloud computing risks within the investment management sector in Cape Town
Get PDFAdoption of cloud computing has become a transformative force in modern information technology, revolutionizing how organisations procure, manage, and deliver IT resources as well as IT services. This treatise explores the implementation of cloud computing in the investment management sector. It focuses on potential cloud security risks, broader implications for businesses and IT ecosystems, and subsequently the treatise conceptualises a strategy that may help in responding to these security risks. The study began by surveying the motivations behind cloud adoption in the investment sector, emphasising the potential cost savings, scalability, and flexibility cloud services offer. It then delves into the challenges faced during implementation, including security concerns, data privacy, compliance issues, and the intricacies of transitioning legacy systems to cloud environments. In response to these challenges, the treatise outlines strategies for successful cloud implementation within the investment sector, in Cape Town, South Africa. It highlights the significance of selecting appropriate cloud service models (for example, IaaS, PaaS, or SaaS) and deployment options (for example, public, private, hybrid, or multi-cloud) to align with organisational needs and objectives. The study followed a qualitative research study. In collecting data an open-ended online survey was sent to participants. The participants were from an investment company in Cape Town. The study employed the design science research paradigm with the aim of developing an artefact. The methodology used was the Nelson Mandela University-Design Science Strategy Methodology (NMU-DSSM) In conclusion, this treatise conceptualises a strategy that may help companies investing in cloud computing technologies to mitigate cyber security and cloud risks. It recommends practices that underscore cloud computing's transformative potential while acknowledging its complexity and challenges. The strategy may serve as a valuable resource for IT professionals, decision-makers, and organisations embarking on the cloud journey, offering guidance and perspectives to navigate the complexities and to realise the potential benefits of cloud technology.Thesis (MPhil) -- Faculty of Engineering, the Built Environment and Technology, School of Information Technology, 202
Total quality management as a tool towards improving Eastern Cape’s department of public works construction
Get PDFThere have been numerous claims regarding how quality management systems facilitate the implementation of Total Quality Management (TQM) among Government Implementing Agents, particularly within the Eastern Cape Department of Public Works and Infrastructure. However, the success rate of TQM implementation in ECDPW projects varies. This study aims to investigate the implementation of TQM within these construction projects. Additionally, five secondary objectives were established to further this investigation. Utilizing a quantitative research approach, data obtained from a semi-structured questionnaire survey was analyzed. The analysis was based on responses from 44 out of 50 questionnaires distributed. Implications: The practical implication of this study lies in identifying the implementation of TQM among Governmental Implementing Agents, particularly within the Eastern Cape Department of Public Works, and understanding the challenges they encounter. The theoretical implications encompass contributing to existing studies that validate quality comprehensively within ECDPW construction projects and suggesting ways they can effectively implement TQM across their processes. The research findings confirmed the challenges and difficulties experienced during the various phases—pre-construction, construction, and post-construction—of projects managed by the Eastern Cape’s Department of Public Works. It was evident that Total Quality Management lacks robust implementation within ECDPW construction projects, directly impacting project quality and the effective execution of quality management systems. A key limitation of this study is the absence of data collection on the professional backgrounds and years of experience of the study participants. During pilot testing, it was found more suitable to identify job roles rather than professional backgrounds.Thesis (MSc) -- Faculty of Engineering, the Built Environment and Technology, School of Built Environment and Civil Engineering, 202
Dislocation imaging of AISI316L stainless steels using electron channeling contrast imaging (ECCI)
Get PDFThis study investigates the use of electron microscopy to image dislocations in high-temperature steels used in the electrical power generation industry. Dislocations play an important role in the mechanical properties of steels, which continuously evolve during component manufacturing and subsequent in-service exposure due to creep and/or fatigue. The dislocation density of the steels can potentially be used as a fingerprint to identify at-risk components that has either reached end-of-life or that was incorrectly manufactured due to forming or heat treatments. Traditionally, dislocation measurements are performed using transmission electron microscopy (TEM) performed on thin foils samples. However, accurate and precise measurements of the dislocation density in steels using TEM remain a challenge due to the time-consuming nature, small sampling volumes, and effects of sample preparation on the quantitative results. The aim of this study is to evaluate and establish electron channeling contrast imaging (ECCI) as a scanning electron microscopy method of quantifying the dislocation densities of power plant steels. This method can be applied to conventionally polished bulk samples allowing for large areas to be sampled. Samples consisting of AISI316L stainless steel were used as a model alloy (large grain size ~100 μm) to compare dislocation imaging using annular dark field (ADF)-scanning TEM (STEM) and ECCI. Three materials states consisting of a cold drawn rod (high dislocation density), annealed rod (low dislocation density), and an annealed sample subjected to cyclic fatigue testing (medium dislocation density) were investigated. Systematic investigations into the data acquisition parameters showed that an incident beam energy (20 kV), beam current (~4 nA), pixel size (5 nm), and working distance (4-5 mm) on a JEOL7001F SEM fitted with a retractable BSE detector could successfully image the dislocation structures for the material states used in this study. The ECCI technique was successfully used to determine the dislocation density in the three material states and the quantitative results showed similar trends as the ADF-STEM quantification results, but with less effort. Future studies using electron backscattered diffraction (EBSD) orientation mapping combined with electron channeling pattern (ECP) calibrations using a single crystal Si sample will allow for ECCI imaging under controlled grain orientations. Furthermore, accurate image segmentation of dislocations from a micrograph remains a key limitation, which can be improved with the use of advanced image analysis based on deep learning approaches. The quantitative dislocation density techniques demonstrated in this study can be adapted not only for studies of other power plant steels (eg. 9-12% Cr Creep Strength Enhanced Ferritic) but also to other materials systems such as aluminium to study the recrystallization processes during annealing.Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 202
Comparing stable isotope ratios and metal concentrations between components of the benthic food web: a case study of the Swartkops Estuary South Africa
No full textEstuarine systems are highly productive ecosystems; however, they are subjected to high anthropogenic pressure such as metal contamination and: increased nutrient loads. The contamination sources of metals and nutrients in urban estuaries are derived: from industrial waste. agricultural and urban runoff that flows into estuaries. An example of such a system is the Swartkops Estuary. industry and three wastewater treatment plants within the Swartkops River catchment are major sources of metal. and nutrient pollution, respectively. The metals accumulate in the environment, are biomagnified up the food web, and transferred from one trophic level to another. At lethal concentrations, metals pose a threat to organisms using the estuary by affecting their physiological and biochemical processes. Stable Isotope analysis has proven to be an effective tool for investigating, trophic linkages in the food chain from a variety of environments. By assessing both metals and stable _isotopes in the. estuary it can provide a more robust understanding of the pathway metals accumulate, biomagnified, and transfer from the environment through the estuarine food web.Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 202
Photocatalytic reduction of CO2 into green fuels on microspherical nanocomposites comprising of CdS, TiO2, ZnFe2O4 semiconductors and heterojunctions
Get PDFHuman anthropogenic activities have led to an increase in CO2 levels resulting in global warming. There is a need to reduce CO2 levels in the atmosphere by capturing the gas and converting the captured CO2 into fuels. Photocatalytic conversion of CO2 into valuable products via photoreduction is a promising technique to reduce carbon dioxide using sunlight and water. Redox reactions between CO2 and water using photocatalysts offer an effective method of lowering CO2, which has detrimental effects on the environment. This dissertation reports the synthesis and characterization of five photochemical catalysts comprising of CdS, TiO2, ZnFe2O4 semiconductors and heterojunctions and their use as photocatalysts for the photocatalytic reduction of CO2 into green fuels. Mott−Schottky plot of TiO2, CdS and CdS/TiO2 confirmed the formation of n-type, n-type, and n-n type material respectively. The band gap of TiO2, CdS, and CdS/TiO2 obtained were 3.21,2.24, 2.04 eV, respectively, the combination of TiO2 and CdS resulted in the lowering of band gap energy which is favourable for photocatalytic reduction studies. XRD of TiO2, CdS and CdS/TiO2 provided relevant information about the various phase reflections of the photocatalysts, it also supported reports confirming the increase in crystallite size of TiO2 anatase phase upon calcination. Chemical environment of the various photocatalysts, such as Ti2p1/2, Ti2p3/2, O1s, Cd3d3/2, Cd3d5/2, S2p1/2 and S2p3/2 were observed in TiO2, CdS and CdS/TiO2. BET surface area of TiO2, CdS and CdS/TiO2 was also observed to be 2.9243, 4.0605, and 9.8450 m2g, respectively. Photocatalytic reduction of CO2 resulted in formic acid, formaldehyde, acetic acid, carbon monoxide, ethanol, and methanol after 12 h. Modification of CdS with TiO2 to form CdS/TiO2 produced high yield of formic acid (217.7 μmol/g) compared to CdS (8.7 μmol/g) and TiO2 (122.5 μmol/g). CdS had high yield of formaldehyde (20.4 μmol/g) and ethanol (57.8 μmol/g) compared to TiO2 (12.9, 3.6 μmol/g of formaldehyde and ethanol, respectively) and CdS/TiO2 (19.7 μmol/g and there was no detection of ethanol). TiO2 shows high yield of methanol (145.2 μmol/g) and is the only catalysts that produced carbon monoxide (52.2 μmol/g) compared to CdS (87.8 μmol/g of methanol) and CdS/TiO2 (50.2 μmol/g of methanol). A detailed elucidation of the various products was reported by means of nuclear magnetic resonance (NMR) spectrometer. ZnFe2O4 and CdS/TiO2/ZnFe2O4 were characterized and employed for photocatalytic reduction of CO2 in water. XRD and XPS confirmed the presence Fe (2+) and Fe (3+) in tetrahedral/octahedral and Zn (2+) in tetrahedral on ZnFe2O4 and CdS/TiO2. CdS/TiO2/ZnFe2O4 presented a lowered band gap of 1.98 eV due to the presence of ZnFe2O4 while the band gap of ZnFe2O4 obtained is 1.95 eV. The Mott-Schottky plots confirmed the conduction (2.81 and 2.59 eV) and valence band (–0.86 and –6.1 eV) of ZnFe2O4 and CdS/TiO2/ZnFe2O4 together with their junctions, respectively. ZnFe2O4 and CdS/TiO2/ZnFe2O4 are p-type and p-n type junctions, respectively. Photocatalytic reduction of CO2 under visible light for 12 h using CdS/TiO2/ZnFe2O4 hollow microspheres nanocomposites produced methanol (182.1 μmol/g), formic acid (1.9 μmol/g), formaldehyde (9.5 μmol/g), ethanol (67.1 μmol/g), and oxalic acid (38.9 μmol/g). Amongst the synthesized catalysts, CdS/TiO2/ZnFe2O4 produced high yield of methanol, ethanol, and oxalic acid.Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 202
A methodology for modernising legacy web applications: subtitle if needed. If no subtitle follow instructions in manual
No full textOne problem faced in the Information Systems domain is that of poorly maintained, poorly documented, and/or unmanageable systems, known as Legacy Information Systems (LISs). As a result of the everchanging web development landscape, web applications have also become susceptible to the challenges faced in keeping up with technological advances, and older applications are starting to display the characteristics of becoming Legacy Web Applications (LWAs). As retaining business process support and meeting business requirements is often necessary, one method of recovering vital LWAs is to modernise them. System modernisation aims to recover business knowledge and provide an enhanced system that overcomes the problems plagued by LISs. When planning to modernise an LWA, guidance and support are essential to ensure that the modernisation exercise is performed efficiently and effectively. Modernisation methodologies can provide this required guidance and support as they provide models, tools and techniques that serve as guiding principles for the modernisation process. Although many modernisation methodologies exist, very few offer a comprehensive approach to modernisation that provides guidelines for each modernisation phase, tools to assist in the modernisation and techniques that can be used throughout. Existing methodologies also do not cater for cases that include both the LWA and migration to modernised web-specific environments. This research study aimed to investigate modernisation methodologies and identify which methodologies, or parts thereof, could be adapted for modernising LWAs. Existing methodologies were analysed and compared using the definition of a methodology, as well as other factors that improve the modernisation process. Modernisation case studies were reviewed to identify lessons learned from these studies so that these could be considered when planning an LWA modernisation. The ARTIST methodology was the most comprehensive modernisation methodology identified from those researched and was selected as the most appropriate methodology for modernising an LWA. ARTIST was modified to the mARTIST methodology to cater for web-based environments.mARTIST was used to modernise an existing LWA, called OldMax, at an automotive manufacturer, anonymously referred to as AutoCo, to determine its ability to support the modernisation of LWAs. Additional tools and evaluation methods were also investigated and used in place of those recommended by ARTIST, where deemed appropriate for the modernisation of OldMax. Limitations set by AutoCo on the hosting and technical environments for the modernised application also required ARTIST to be adapted to better suit the use case. The steps taken during this modernisation were documented and reported on to highlight the effectiveness of mARTIST and the tools used. The result of this modernisation was that the modernised web application, ModMax, was evaluated to determine the success of the modernisation. The modernisation of OldMax to ModMax, using the mARTIST methodology, was found to be successful based on the criteria set by the ARTIST methodology. Based on this, mARTIST can successfully be used for the modernisation of LWAs. To support future modernisations, an evaluation method for determining technical feasibility was developed for LWA, and alternate tools that could be used throughout modernisation exercises were recommended.Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 202