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Dynamically responsive scaffolds produced by additive manufacturing
No full textThesis (Master: Engineering: Mechanical Engineering)--Central University of TechnologyAdditive manufacturing (AM) and design methodology of compliant mechanisms, topology optimisation, lattice structures, metamaterials, etc. allows for the production of complex customised components with very specific properties. One of these types of components is dynamically responsive scaffolds (DRS), made of thin geometric structures that adjust mechanical behaviour to the required loading and direction. This work presents design, numerical simulation, production, and testing of DRS structures as two-dimensional scaffoldings. The scaffoldings were printed in different directions to compare the isotropic behaviour of the AM samples for tensile tests. The methodology for DRS physical testing was demonstrated. The auxetic behaviour of the samples were also studied. Auxetic behaviour will be highly beneficial for DRS as it would allow the DRS to distribute the force more evenly in the event of an impact on the scaffolding. Three series of experiments and numerical simulations were done. First, the scaffoldings were produced from ABS (acrylonitrile butadiene styrene) filament using fused deposition modelling (FDM) system to obtain a basic understanding of DRS mechanical behaviour. Second, the polyamide (PA 2200) specimens were produced with selective laser sintering (SLS) machine. The SLS scaffolding specimens were tensile tested that gave a reading on the tensile force experienced by the specimens during elongation. The data from the tensile tests were then processed into force-over-displacement graphs, and the results were studied. Videos of the tensile tests were also taken to examine the deformation of the specimens as they elongated. Finally, two of the most promising designs were selected and fabricated in a metallic material (Ti6Al4V alloy) by laser powder bed fusion (L-PBF). The physical testing and numerical simulations of Ti6Al4V DRS samples were compared and discussed. This study aims to lay a foundation for the development of DRS, which could one day be used as medical implants that require specific mechanical properties and behaviour that would otherwise not be possible. An essential application for designed DRS could be a cranial implant that can grow with the patient removing the need for future surgeries to replace the implant due to the growth of the skull until it is fully developed. The compliance of the scaffolding, the stiffness, and the support perpendicular to the growth direction make designed DRS especially promising for this application
Human immunodeficiency virus type 1 drug resistance among patients failing second-line antiretroviral treatment in Butha-Buthe and Mokhotlong, Lesotho
Full text linkThesis (Master: Health Sciences (Biomedical Technology))--Central University of TechnologyBackground: To date, there is no cure for HIV. However, antiretroviral treatment (ART) is used to control the replication of HIV and many people living with HIV take ART. Unfortunately, over time, some patients develop drug resistance which is becoming a major public threat limiting future treatment options for people living with HIV. HIV-1 drug resistance is defined as the ability of HIV-1 to mutate and reproduce itself in the presence of ARV drugs. This occurs as a result of: (a) poor adherence to treatment; (b) inadequate potency of ARVs; (c) suboptimal drug levels and (d) pre-existing resistance. There are two types of resistance-associated mutations (RAMs) namely acquired and transmitted. When an individual is infected with HIV-1 resistant strain, it may become the dominant strain for further transmission leading to increasing number of antiretroviral-naive patients and reducing their therapeutic effectiveness. HIV drug resistance testing is a test used to detect the presence of RAMs to HIV type 1 (HIV-1). Currently patients are switched empirically in the country. Therefore, it is crucially important to understand the HIV drug resistance pattern in order to find ways how to limit the occurrence. This will helpful in the clinical decision making and selection of regimens upon treatment failure. Objective: The objective of the study was to access the prevalence and patterns of HIV resistance-associated mutations in patients with an unsuppressed viral load when taking second-line ART in Butha-Buthe and Mokhotlong districts, Lesotho. Methods: In a retrospective study, we used convenience sampling and sequenced all eligible (patients on second line ART with a viral load ≥ 1000 copies/mL) stored leftover plasma samples taken between January 2016 and October 2020. The study was conducted at Seboche Hospital Laboratory which served all health facilities (hospitals and clinics) in the northern region of Lesotho. During testing, RNA extraction was done manually using the Purelink Viral/DNA kit. PCR amplification and sequencing of the protease (PR) and reverse transcriptase (RT) region was done using the Amplification and Sequencing module kits developed by Thermo Fisher Scientific. Consensus sequences were derived, aligned, and analysed using the web-based Recall software. The Stanford HIV Drug Resistance Database was used to interpret the presence or absence of drug resistant mutants. Results and discussion: Out of 55 patients’ samples, 30 samples were successfully amplified and sequenced. The median age was 41 years (IQR: 30 to 49) and the majority (62%) of participants were female. The median duration on a second-line regimen at the time of phlebotomy was 1.9 years (IQR: 0.5 to 3.0). The majority of patients (94%) were taking ritonavir-boosted lopinavir-based ART. Major RAMs were observed in 62% of participants; one patient had major RAMs in the PR while 18 had RAMs in the RT region. All participants had HIV-1 subtype C. The most frequent mutations conferring resistance to nucleoside reverse transcriptase inhibitors were M184V (31%) and K70R/E (16%), while the most frequent mutations conferring resistance to non-nucleoside reverse transcriptase inhibitors were K103N (38%), P225H (19%) and G190A (19%). The observed PR mutations from one sample were M46I, I54L and V82L. Only 10 (31%) patients had RAMs which conferred resistance to their second-line regimen. Though RAMs were detected, the majority of patients had three active drugs in their second-line regimen and many observed mutations likely conferred resistance to their previous regimens. Conclusion: Though 62% of patients had RAMs, only 31% had RAMs conferring resistance to their second-line regimen during the first 2 years after switch to second-line ART, indicating that adherence plays a major role in second-line treatment failure. These RAMs reflect the reality of HIV care in resource-limited settings such as Lesotho. Adherence should be strengthened among people with treatment failure while taking second-line ART in order to avoid development of resistance mutations
Evaluation of occupational exposure to wood dust and noise among sawmill workers in the Gert Sibande district municipality
Full text linkThesis (Master: Health Sciences: Environmental Health)--Central University of TechnologyWood dust is a human carcinogen based on an increased risk of nasal and sinonasal cancer. Occupational exposure to hazardous noise above the 85 decibels, A-weighted (85 dB[A]), eight-hours time-weighted average (8-hour TWA) can cause noise induced hearing loss (NIHL). The aim of the study was to measure and determine the timeweighted average (TWA) occupational exposure level (OEL) to wood dust and noise and compare the results with the OEL for wood dust and the noise rating limit for noise and assess hearing loss and respiratory symptoms and use of personal protective equipment (PPE) among sawmill workers within the Gert Sibande District Municipality. A comparative cross-sectional study comprising of 137 exposed and 20 unexposed workers randomly selected, using simple random sampling was undertaken between January and March 2021. Self-reported hearing loss and respiratory symptoms were evaluated using a self-administered questionnaire. Personal and area wood dust exposure levels were measured using calibrated Giliair-3 personal air sampling pumps, while personal and area noise surveys were conducted using calibrated SV104IS noise dosimeters (SVANTEK, Poland) and a type 1 sound level meter (Soundpro SE/DL, U.S.A.). Data was analysed using the Microsoft Excel 2019 analysis Tool Pak to obtain a summary of descriptive statistics. The geometric mean, standard deviation, minimum and maximum values were calculated. Mann-Whitney U test was used to test the significance of the differences between values in sawmill A and B while t-test was used to compare the mean time-weighted averages of occupational exposure levels to noise from sawmills A and B. Discrete data from questionnaire results were presented as percentages and tables. The t-test was used to compare continuous variables, while the chi-square test was used to test categorical responses. Fisher's test was employed when the anticipated number was below 5. A significance level of 0.05 was used. The prevalence of symtoms such as chest pains or shortness of breath was higher among the unexposed group (50%) than the exposed group (44%). Furthermore, the participants in the exposed group suffered from tinnitus (ringing in the ears) (50%) and ear infections (21.43%). Moreover, the unexposed group reported suffering from tinnitus (33%) and ear infections (66.67%). The exposed group (86.86%) reported always wearing the personal protective equipment (PPE) than the unexposed group (75%) who wear it sometimes. Moreover, the exposed group (48.48%) did not wear PPE consistently due to not being available while all participants from the unexposed group reported other reasons for not wearing it. The geometric mean(GSD) for personal respirable wood dust exposure level at sawmill A was 0.9(4.8) mg/m3 while at sawmill B was 0.57(0.75) mg/m3 . The geometric mean(GSD) for personal respirable wood dust exposure level at sawmill A was 0.9(4.8) mg/m3 while at sawmill B was 0.57(0.75) mg/m3 . The geometric mean(GSD) for personal total inhalable wood dust exposure level at sawmill A was 0.37(0.94) mg/m3 while at sawmill B was 1.19(16.91) mg/m3 . Moreover, the geometric mean(GSD) for area respirable wood dust exposure at sawmill A was 0.13(0.09) mg/m3 while at sawmill B was 0.8(0.6) mg/m3 . Likewise, the geometric mean(GSD) for area total inhalable wood dust exposure at sawmill A was 0.13(0.16) mg/m3 while at sawmill B was 0.54(0.55) mg/m3 . The geometric mean(GSD) for area noise exposure level at sawmill A was 90.05(8.02) dB(A) while at sawmill B was 90.14(7.94) dB(A). The geometric mean(GSD) for personal noise exposure level at sawmill A was 92.26(4.35) dB(A) while at sawmill B was 92.24(2.65) dB(A). Occupational exposure to wood dust and noise was associated with respiratory symptoms such as chest pains or shortness of breath and hearing loss conditions or symptoms such as tinnitus (ringing in the ears) and ear infections (Ha accepted and H0 rejected). The majority of the results for wood dust samples were below the South African OEL, while majority of the results for noise exposure levels were above the noise rating limit (Ha accepted and H0 rejected). A non-significant difference on the levels of exposure to noise was observed when comparing the results of sawmill A to sawmill B (H0 accepted and Ha rejected). Similarly, a non-significant difference on the levels of exposure to wood dust was observed when comparing the results of sawmill A to sawmill B (H0 accepted and Ha rejected). The findings suggest that sawmill owners should take steps to lower the levels of exposure to noise and wood dust to help protect workers’ health.Implementation of engineering and administrative controls supplemented by appropriate use of the fit-tested hearing protective devices (HPDs) with the higher noise reduce reduction (NRR) or single number rating (SNR) and the respiratory protection devices (RPDs) with the higher assigned protection factor (APF) is recommended based on the exposure levels recorded. Tobacco or cigarette smoking should be discouraged because when associated with exposure to wood dust and noise may increase risk of respiratory symptoms and development of high frequency hearing loss
Optimal energy management of solar-assisted heat pump water heating systems: a case of student residences at the Central University of Technology, Free State
Full text linkThesis (Master: Engineering: Mechanical Engineering)--Central University of TechnologyIn South Africa, more than 40% of the energy produced, is estimated to be consumed in the commercial sector. Organizations, such as universities in South Africa, are faced with increased pressure to manage energy demands and escalating energy costs. This has resulted in the country currently facing ambiguous tariff increases, at short intervals, by the power utilities and rolling blackouts that could possibly lead to a grid shutdown. On the other hand, most institutions were not designed to be energy efficient, as they were mostly constructed in an era when energy optimization did not offer sufficient financial benefits. Therefore, energy efficiency is seldom viewed as a core university function. Standard electric storage tank-water heaters (ESTWHs) are the most used systems for sanitary water heating and are a major contributor to the undesirable high morning and afternoon peaks in energy demand. Another reason is that these systems rely solely on thermostat systems for operation control, with no other energy management activities (or technologies) in place. In addition, the thermostat automatically switches ON/OFF, to heat water to the end user’s set desired thermal level throughout the day, whenever the temperature drops below the set point, due to standby losses. All these things, therefore, add to the cost of the monthly bills of the users. Using renewable energy source water heating systems, such as air-source heat pump water heaters (ASHPWHs) and solar water heaters (SWHs), may further assist to reduce excessive energy demand and the cost of hot water production. However, these standalone water heating systems are insufficient, in the case of a great deal of hot water production whereby continuous energy supply is needed. This is due to the slow heating processes of the ASHPWHs and SWHs being solely dependent on thermal heat from the sun to heat the water. Furthermore, like the ESTWHs, the electricity-driven HP units on the market use primary thermostat control systems, which may further contribute to the energy consumption during the peak period. Solar-assisted heat pump water heaters (SAHPWHs), are a possible solution to the escalating electricity charges, faced by the South African community, particularly for the continuous demand for sanitary hot water in the commercial sector, such as university student residences. The solar system may provide a great amount of thermal energy to supply the heat pump unit during the time when the sun is available, while the heat pump consumes a minimal amount of energy, during the time when there is minimal to no solar energy available, to heat the water. These SAHPWH technologies may be a solution to assist with reducing the high energy demand, which will further help alleviate the pressure on the electricity supply grid. Additionally, implementing an optimal energy control scheme, to load shifting by the TOU tariff plan, may help alleviate demand strain on the supply grid, as well as optimize energy savings, while maintaining the consumer’s thermal comfort level. In this study, an IDX-SAHPWH system, operating under an optimal energy control scheme, integrated with the load shifting by TOU pricing plan, is proposed for the commercial sector. A student residence was used as a case study. A mathematical model of the proposed system was developed, and the optimal operation control problems were formulated. The Solving Constraint Integer Programs (SCIP) solver, in the MATLAB interface optimization toolbox, was used for the simulations, with the considered computational variables taken at 20-minute intervals. The baseline model was further simulated using the same component sizing, as well as under the same climate conditions. From the simulation results, the proposed system, under the optimal energy control scheme integrated with the load shifting by TOU pricing plan, operates optimally, as it avoids the peak and standard periods of the TOU tariffs, which guarantees savings in energy and costs, as compared to the baseline ESTWH. The proposed system ensures that water is heated during the off-peak period to the highest temperature that will be able to maintain the thermal level of the consumers, throughout the high TOU tariff periods. The techno-economic analysis of the optimally controlled proposed system and the baseline systems were conducted and presented for a project lifespan of 20 years. All cost aspects were considered in the analysis and, from the results obtained, the IDX-SAHPWH system showed significant savings. The cost savings obtained from the winter and summer seasons, as well as annual, are 76.0 %, 75.6 % and 75.8 %, respectively. The break-even point of the project is during the 9th month of the first year of the project, with a possible savings of 71.5 % at the end of the project's lifetime. It may therefore be concluded that the aim of this study has been met as the IDXSAHPWH system, when operated with the optimal energy control scheme, integrated with the load shifting by TOU pricing plan, shows a very significant savings in costs, which maintaining the thermal comfort level of the consumers. Furthermore, the system may contribute to the load reduction during peak energy usage periods on the electricity grid supply. As a result, this system can be used in any commercial enterprise, that has a high demand for sanitary water heating
Flatness based cooperative control of multiple mobile robotic systems
Full text linkThesis (Master: Engineering: Electrical Engineering)--Central University of TechnologyCooperative multi-robotic systems can be more useful in numerous applications when compared to single-robotic systems. However, to ensure that cooperative systems execute tasks accurately, highly effective control architectures are vital. This study aims to improve the coordination control of a model based cooperative multiple mobile robotic system using differential flatness theory. To achieve this, a comprehensive analysis of literature on fundamentals of wheeled mobile robots and their cooperative systems was conducted. Then, mathematical modelling is performed for a cooperative robotic system composed of differential drive wheeled robots. First the kinematic model is presented to describe the motion of a robot without consideration of the forces causing it. Following that, the dynamic model is presented to describe the robot's motion in relation to forces applied to it. These models allowed for better design of a control system and paved way for the differential flatness characterisation of the mobile robotic system. Next, the robot differential flatness characterisation and analysis were performed, and the flatness properties were exploited to design a flatness-based control algorithm for motion planning and to generate trajectories and track them. Thereafter, the formation model was derived using a leader-follower formation. In this approach, three similar robots were modeled. Among the robots, one is selected as leader, and it is followed by two follower robots. Only the leader robot has access to information about the desired tracking path and all follower robots rely on it to coordinate their motion. Also, each follower must maintain a constant defined distance and orientation from the leader. Lastly, a flatness-based formation controller was developed. Tests were conducted to compare the flatness-based controller with the conventional PID controller. According to the results, Flatness-based controllers significantly reduce tracking errors of the cooperative system, whereas PID controllers have slightly higher tracking errors. This is because increasing the gains of the PID controller beyond a certain threshold causes it to get saturated, whereas the Flatness controller can be adjusted without any concern for saturation. The key findings of this study was that differential flatness allows for the whole system to be represented by a reduced number of variables and thus the computational cost is significantly reduced especially when dealing with multiple robots that could otherwise entail solving large robotic model differential equations. This significantly simplifies the motion planning problem of the cooperative system. Also, a differential flatness characterisation of the robotic formation enabled the linearisation of the system to a stable linear equivalent system. Furthermore, in flat output space a simple polynomial-based trajectory planning can be used, that is simplifying the trajectory generation problem. Additionally, trajectories are solved without integrating robot model differential equations. Thus, it is concluded from this study that differential flatness theory improves coordination control of cooperative multiple mobile robotic systems
The implementation of inclusive education by primary school educators in selected primary schools in Warmbaths circuit
Full text linkThesis (Master : Education)--Central University of TechnologyThe focus of the study was to investigate the implementation of inclusive education by primary school educators in selected schools in the Warmbaths circuit. The research approach (methodology) utilised in this study was qualitative, guided by the interpretive paradigm.
For this qualitative case study, a purposive and convenient sampling method was used to choose five educators, five school-based support team (SBST) members, two deputy principals, and two school principals. The total number of research participants was 14.
Semi-structured one-on-one interviews, open-ended questionnaires, and document analysis were utilised to gather data on the execution of the inclusive education policy. Thematic analysis was employed to interpret and analyse data.
The findings of the study were discussed according to themes and sub-themes which emanated from research questions. The findings of the current study show that most of the educators defined the concept inclusive education in different ways. Equally importantly, the study revealed that educators were unable to implement a policy of inclusive education. The majority of respondents in the findings emphasised the importance of regular workshops and monitoring in primary schools for the successful implementation of inclusive education. In conclusion, the findings of the study recommend, among others, that the Department of education provides more resources to public primary schools
Pre-Service Teachers’ Academic Identity and their Lived Experiences in Remote Learning: The New Normal in Curriculum Practice
Full text linkResearch ArticleThe Ministry of Tertiary Institutions of South Africa charged post-secondary institutions to implement measures to achieve the government's social distancing policy. Institutions shifted to remote learning to sustain their core business of teaching and learning. However, there were concerns with the implementation of these measures. For instance, pre-service teachers were seen as ill-equipped and poorly supported during remote learning. This paper aims to contextualise the identity of pre-service economic and management science teachers and reflect on their experiences of curriculum practice during remote learning. Architecture theory was used as the main lens for this study. Furthermore, the goal is to reflect on their adaptation to remote learning as the new normal. Participants’ experiences and factors that affected them are discussed as data collected using the critical participatory action learning and action research (CPALAR) approach as a form of critical education science. Critical discourse analysis was used to arrive at the following broad findings: firstly, higher learning institutions are obligated to create practical learning experiences for pre-service teachers. Secondly, participants were directly affected academically, socially, and psychologically. This paper concludes with the recommendation that hybrid learning as the new normal is the future of teaching and learning and should be embraced
The impact of social issues on the academic performance of secondary school learners in the Palala circuit division of Waterberg district in the Limpopo Province
Full text linkThesis (Master: Education)--Central University of TechnologySocial issues in secondary schools in South Africa are a growing phenomenon, regardless of a new government and newly amended policies promising equal opportunities for access to adequate education. There are still several barriers that prevents and forces learners to drop out of school or not consider school as an important institution to draw knowledge from. As such, it is important to disclose some of these social issues and their impact on the academic performance of learners. The study explores the social issues that contribute to the poor performance of secondary school learners in South Africa, specifically the Palala circuit in the Waterberg district, Limpopo. A mixed research method is used (qualitative and quantitative) to investigate the possible improvements that could be used to deal with the social issues facing secondary school learners. Questionnaire surveys were distributed to 10 principals, 10 Head of Departments (HoDs), 10 Life Orientation teachers, and 30 learners, 3 per school in the 10 selected schools from the Palala circuit division. Interviews were conducted with the same participants. The study revealed some of the social issues that affect the academic performance of learners in secondary schools in the Palala circuit division, with some of the predominant social issues being poverty, teenage pregnancy, and unemployment. The key findings showed a correlation between what has been reported through literature, and this study. Findings indicate that participants selected prominent social issues that affect the academic performance and based on the top five social issues that were selected, literature includes those selected. Considering the comments from the participants, it shows how the trends of the social issues interrelate to a negative implication on the academic outcomes of secondary school learners. Learners and teachers revealed known barriers and challenges they face with the mentioned social issues. The study recommends that schools should establish functional health, alcohol, and drug committees that will ensure that learners do not use drugs, alcohol, and other substances that could lead to poor academic performance due to consistent absenteeism, bullying, and dropout. These committees should also invite learners’ role models, social, and former students to give motivational talks that would show how they themselves addressed challenges when they were still learners and the dangers of not focusing on their schoolwork
An analysis of health and safety communication and its impact on incident occurrence at Eskom: Eastern Cape operating unit.
Full text linkThesis (Master of Health Sciences: Environmental Health)--Central University of Technology, 2022This research focused on the various techniques used to communicate workplace health and safety messages. It further fixated on the impact and barriers of inefficient health and safety communication on Eskom: Eastern Cape Operating Unit’s health and safety performance; as well as the common workplace health and safety injuries and incidents and the leading causes to the injuries and incidents. The current study followed a quantitative research approach, in which relevant data on health and safety incidents from 2015 to 2019 was collected from Systems, Applications and Products in data processing of Environmental Health and Safety (SAP EH&S). Furthermore, a survey was conducted through the distribution of a questionnaire to managers, supervisors, engineers, and operators. Task observations were also conducted while operators were performing their work. A total of 614 incidents were analysed where the results revealed motor vehicle accidents and hand injuries as the most prominent types of incidents occurring at Eskom: Eastern Cape Operating Unit. The results further showed that 86.5% of the incidents were motor vehicle accident occurred in the Mthatha Sector. Unsafe worker behaviour, such as non-adherence to the wearing of person protective equipment (PPE)
and negligence were found as the most common causes of incidents. The results of the questionnaire distributed to 294 participants showed that participants agree that non-adherence to rules was the most common unsafe behaviour that led to the occurrence of incidents. Further, 50% of the participants agreed that the health and safety message communicated were unclear in their transmission. There is sufficient evidence indicating that communication strategies in the workplace need to be strengthened to ensure the reduction of potential hazards pertaining to health and safety performance and incident occurrence. There is a surge of workplace health and safety incidents due to unsafe worker behaviour, despite legislative interventions. Moreover, inadequate communication methods and language barriers have a negative impact on Eskom: Eastern Cape Operating Unit’s health and safety performance. Therefore, there is an urgent need for improved health and safety communication methods, using innovative
systems
The viability of in-silico analysis of cyp51s in Eurotiomycetes species for identifying novel azole resistance mechanism
Full text linkThesis (Master of Health Sciences in Biomedical Technology)--Central University of Technology, 2022The classification and characterization of cytochrome P450 monooxygenases in Eurotiomycetes species of fungus have unfolded various structure-function correlates of the enzyme and its variants from the perspective of evolutionary history and drug resistance. The present thesis explored the attributes of azole resistance of Aspergillus strains in terms of point mutations and polymorphisms in CYP51 and CYP51. The azole resistance in Eurotiomycetes was studied Aspergillus fumigatus as the case study. Studies reveal that Aspergillus houses CYP51A and CYP51B and both of them are required for functionality of the CYP51. The CYP51 is chemically 14-alpha demethylase that converts lanosterol to ergosterol. Ergosterol helps in the membrane fluidity and virulence of the fungal isolate. The enzyme is a putative target of azoles, especially the active heme molecule within the active site. The present study was based on in-silico analysis that involved BLAST, FASTA, phylogenetic analysis, and protein modeling to explore the novel single nucleotide polymorphisms and point mutations and its extrapolation to CYP51 structures as enlisted in the PDB database. The study showed that deletion mutations in CYP51 could lead to non-functional 14-alpha demethylase. Moreover, the deletion mutations could also potentiate the over activity of the ABC transporter proteins (efflux pump) because the alignment of the amino acid residues in mutated CYP51 nearly matched that for ABC transporter proteins in the same fungal isolate. It was further contended that mutations in CYP51 promoter could have sensitized the binding of various transcription factors that reduced the expression of 14-alpha demethylase