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Food security and related wellness indicators of health sciences students in central South Africa during Covid-19: a programme to mitigate the impact of isolated, confined and extreme environments
Full text linkThesis (PhD: Environmental Health)--Central University of TechnologyThe negative impact of the COVID-19 pandemic resulting from isolated, confined, and extreme (ICE) environments brought about by strict lockdown restrictions has been widely documented, including its effects on Higher Education. Decreased physical activity, change in nutritional habits, weight gain, food insecurity, inadequate quality sleep, poor mental health and decreased academic performance are amongst manifestations of such impacts. In developing economies, the impact of the pandemic has been argued to be more pronounced as a result of limited resources and infrastructure. The aim of this study was to investigate possible changes in the nutritional health and related wellness indicators of students at a selected higher education institution in South Africa due to COVID-19 circumstances, and to propose a programme to the Higher Education portfolio that may mitigate negative impacts during future events resulting in ICE environments. Such future events may include political instability and conflicts, pandemics, climate change consequences, economic decline and the like. A mixed method investigation was performed using both questionnaires and focus group discussions amongst final year students selected from four health science curricula at a prominent South African university of technology (UoT). The questionnaire and focus group discussions measured similar constructs and utilised existing, validated questionnaires, including Household Food Insecurity Access Scale, SA Demographic and Health Survey surveys, and questionnaires to assess adherence to diet and exercise advice, as well as Depression, Anxiety and Stress Scale of 21 Items. Data from questionnaires and focus group discussions were coded, analysed, and interpreted, whereafter a targeted and aligned mitigation programme was proposed for Higher Education institutions. To achieve the former, design thinking and project management processes were integrated towards a suitable and effective methodology to develop interventions and strategies for the challenges that emerged from the findings of the study. The adapted and integrated design process consists of six phases: (1) Initiation and planning, (2) Empathise, (3) Execute and define, (4) Ideate, (5) Prototype, (6) and Closure. The results of the study showed that the majority of the participants (n=148) that completed the questionnaires were female (82%), while all focus group participants (n=17) were females, resulting from the sampling methodology applied. Questionnaire participants mainly resided in urban areas (76%) during the pandemic, while 36% had parents/guardians at home. Nutritional-related data indicated that food insecurity existed at varying levels amongst 84% of questionnaire participants. The main reason for food insecurity was financial constraints, and correlation statistics indicated participants from rural areas were more food insecure. Adequate water was available to participants during the pandemic, although the quality of the water may be questionable. Questionnaire participants’ dietary intake changed, with mainly a decrease in sugary and salty snacks, although maintaining fruit, vegetables, and meat intake. Focus group participants indicated an increase in the intake of starchy food such as noodles and reverting to binge eating, primarily due to emotional stress. Dietary intake changes were also attributed to limited resources, e.g. funds and electricity. Only a few participants were aware (18%) or utilised (1%-4%) nutritional-related, as well as health and wellness support services that were offered at the institution during the pandemic. This observation suggests that respondents were unaware of the services offered by the institution. Findings on related health and wellness indicators showed that most participants perceived their general health to have deteriorated, and they fell ill more often. Questionnaire participants reported considerable weight gain (33%) or slight weight gain (24%), as well as decreased physical activity with an increase of 11% in the no exercise category. Similarly, focus group participants indicated weight fluctuations, including weight gain, as well as more sedentary behaviour. The reasons for decreased activity included lack of motivation (17%) and inaccessible training facilities such as gymnasiums (24%). Both focus group and questionnaire participants’ reported deterioration of mental health with the anxiety levels of questionnaire participants in the extreme category. Inferential statistics analysing the inter-relationships amongst tested variables indicated that a statistically significant relationship exists between food insecurity and poor mental health. Utilising a mind map methodology, interventions and strategies were developed aimed at mitigating the challenges/impacts that emerged from the findings on nutritional and related health and wellness indicators of students. These interventions and strategies were classified into two categories: awareness and communication, and resources. In the awareness and communication category, improved communication of offered support services, awareness campaigns, developing skills and knowledge and evaluation of the student cohort as part of ensuring adequate capacity of support services, were suggested interventions. The resources category consisted of the following strategies: a wellness software application utilising Artificial Intelligence (AI), an adequate food aid programme with easy access, as well as wellness support that includes nutritional and fitness support. It was recommended that the proposed programme be implemented by Higher Education institutions in accordance with the Nadler-Tushman (N-T) model of congruence. The N-T model was selected due to its authority and proven effectiveness, as well as its simple and pragmatic approach to identify gaps and shortcomings. The model is also focused on a process of transformation – the latter being a priority within the current-day Higher Education sector and peripheral institutions in developing countries. The proposed programme is not a one-size-fits-all model, whereas institutions are advised to implement it into their specific contexts and ensure congruence between all the elements. In conclusion, the study clearly showed that the ICE environment that resulted from the COVID-19 pandemic negatively impacted the students’ nutritional status, especially food security. Moreover, these COVID-19 circumstances also had a significant impact on health and wellness indicators of students. A need was identified for a health and wellness programme at Higher Education institutions, including improved awareness, health and wellness training and support. As a result, a programme with strategies and interventions has been proposed to institutions that must reflect on their current support service structures to amend the strategies to suit their specific circumstances. Therefore, the proposed programme serves as point of departure for institutions wanting to ensure maintenance of student health and wellness, as well as academic performance during future ICE events. Ultimately, this study endeavoured to cast light on the impact of isolated, confined, and extreme environments brought about by events currently rife on the international stage, and to suggest mediation strategies to cope in such environments, with a focus on Higher Education students
Mycotoxigenic fungi and multimycotoxin contamination in medicinal plants sold in the Free State province, South Africa.
Full text linkThesis (Master: Health Sciences: Environmental Health)--Central University of TechnologySouth Africa has a long history and extensive use of medicinal plants in traditional medicine, but relatively few studies have been conducted on their contamination with moulds and mycotoxins. The purpose of the present study was to characterise medicinal plant trade and determine the extent of fungal and mycotoxin contamination among frequently sold medicinal plants in the Free State Province not yet reported before. A market survey was conducted using semi-structured interviews across 29 locations with 48 respondents. Fungi species were isolated as single colonies morphologically and identified using molecular techniques. Mycotoxin analysis of samples was done using Ultra High-Pressure Liquid Chromatography-Tandem Mass Spectrometry (UPLC-ESI-MS/MS) for the simultaneous detection of AFB1, DON, FB1, FB2, FB3, NIV, OTA, and ZEN. The trade in medicinal plants was mainly dominated by street vendors and muthi shops made up mainly of Sotho, Zulu, Ndebele ethnicities. Traders were mostly men who worked full time with no other income sources and had been in business for 0.5 years up to 26 years. The mean monthly income for men was ZAR 1 825, and for women was ZAR 760. A total of 165 ethno-species belonging to 48 families were the most frequently sold medicinal plants. Salient families for the medicinal plant trade in the province were Asteraceae, with 13 species, followed by Liliaceae (5) and Fabaceae (3). The dominant species were Hypoxis latifolia, Dicoma anomala, Helichrysum odoratissimum, Elephantorrhiza elephantina, Tulbaghia alliacea, and Pentanisia prunelloides. Thirty-four medicinal plant samples were purchased from street vendors and muthi shops in the Free State Province. Approximately 26% of the samples had no fungi contamination, whilst 74% were only contaminated by one or more fungal species. The fungal load in positive samples purchased from street vendors ranged from 1 × 106 to 8.4 × 107 with a mean of 2.55 × 107 CFU/g. Whereas for muthi shops, the study reported a mean fungal load of 2.33 ×107 , ranging from 1 × 106 to 8.4 × 107 CFU/g. For all positive samples, the fungal load was above 1 × 106 CFU/g (above the WHO limit). A total of 54 fungal isolates were recovered, comprising of 17 species. Species belonging to Penicillium, Aspergillus, Fusarium, and Purpureocillium were the most dominant in the medicinal plant samples. About 59% of the fungal isolates screened for their ability to produce mycotoxins were toxigenic, whilst 41% did not produce any detectable quantities of mycotoxins under investigation. All fungal isolates did not produce, nivalenol, ochratoxin A and zearalenone in culture. Ten out of 34 samples tested positive for mycotoxins as follows; AFB1(10%); OTA (10%), FB1 (30%), FB2 (50%), FB3 (20%) and ZEN (30%). Mean concentration levels ranged from AFB1 (15 µg/kg), OTA (4 µg/kg) FB1 (7-12 µg/kg), FB2 (1-18 µg/kg), and FB3 (1-15 µg/kg), ZEN (7-183 µg/kg). Multimycotoxin contamination was observed in 30% of the positive samples with fumonisin derivatives. The concentration of AFB1 reported in this study is above the South African permissible limit for AFB1 (5 µg/kg). Fumonisin concentration did not exceed the South African limit set for raw maize grain (4000 µg/kg of FB1 and FB2). ZEN and OTA are not regulated in South Africa but reported concentrations were below EU Commission-set limits. The study findings indicate the prevalence of mycotoxin contamination in frequently traded medicinal plants, mycotoxins pose a significant health risk to consumers due to their additive or synergistic health effects. Routine monitoring of multiple mycotoxin contaminations, human exposure assessments using biomarker analysis, and establishing regulations and standards.is essential. Therefore, strategies to mitigate mycotoxin contamination should be enacted at major markets, traditional healers, local suppliers, muthi shops and street vendors
In vitro antibacterial activity of gunnera perpensa and elephantorrhiza elephantina against human pathogenic bacteria
Full text linkThesis (Master: Health Sciences: Biomedical Technology)--Central University of TechnologyINTRODUCTION: In the history of the African population, medicinal plants are a heritage that has been able to be preserved and used in modern times. The use of medicinal plants is still regarded as a treatment option in the current healthcare sector and among rural communities. Traditional medicinal plants have been used by African communities for many years as they are more affordable, easily accessible, less toxic, and more trustworthy in African cultures because the knowledge of remedies practised by traditional healers has been passed down by the ancestors through cultural practices in current and past generations. In recent years, even with the modernisation of the healthcare system, people still seek help of traditional healers. Multidrugresistant (MDR) bacteria have increased at an alarming rate over the recent decades and have caused a substantial health burden. MDR bacteria are pathogenic bacteria that are naturally harmful and cause severe infection/disease among humans. These illnesses/conditions may include abdominal pain, bladder problems, cancer, colds, earaches, endometritis, gastrointestinal parasites, gonorrhoea, heart diseases, hypertension, impotence, infertility, kidney problems, poor appetite, rheumatic pains, scabies, syphilis, and urinary infections. This study sought to assess Elephantorrhiza elephantina and Gunnera perpensa as antibacterial agents used to treat infections associated with MDR bacteria. METHODS: Medicinal plant extracts (using roots/rhizome) were prepared by maceration with methanol and water. Secondary metabolites were qualitatively and quantitatively assessed, while antibacterial activities were determined using the disk diffusion assay and the p-Iodonitrotetrazolium chloride assay on the following Grampositive bacteria: Staphylococcus aureus, S. epidermidis, S. saprophyticus, and Bacillus subtilis, and the following Gram-negative bacteria: Klebsiella pneumoniae and Escherichia coli. Further investigation of the antibacterial activity and the effects of E. elephantina methanol extract on the bacterial morphology of S. aureus was performed. This was investigated using a scanning electron microscope (SEM) and transmission electron microscope (TEM). RESULTS: The phytochemical analysis of the plants confirmed that the following phytochemical compounds were present in both the methanol extract of G. perpensa and E. elephantina: alkaloids, glycosides, flavonoids, tannins, phytosterols, and phenols. Gallic acid equivalents (GAEs) of the estimated phenolic concentrations ranged from 0.140 ± 0.0076 to 0.068 ± 0.0025 mg (GAE). The estimated flavonoid concentrations ranged from 0.905 ± 0.0190 to 0.375 ± 0.0073 mg (QE/g). The antibacterial activity results of the E. elephantina methanol extracts showed strong antibacterial activity against S. aureus, B. subtilis, and K. pneumoniae and indicated the minimum inhibitory concentration at concentrations of 60 µg/mL, 125 µg/mL, and 60 µg/mL respectively. The SEM and TEM evaluation of S. aureus showed major structural changes, including damage to cell walls, which was evident from holes in the cell surface. The loss of cellular or cytoplasmic contents resulted in shrinkage of the cell, which was seen by the wrinkled and indented surface of the cell. CONCLUSION: The antibacterial activity of G. perpensa demonstrated strong activity against Gram-positive bacteria S. aureus and B. subtilis; however, poor activity was demonstrated by the methanol extract and no activity was seen from the aqueous extract against the Gram-negative bacteria E. coli and K. pneumoniae. The effects of E. elephantina on the bacterial cell wall supported the antibacterial properties of the plant, as the results of the SEM and TEM show how the plant extract caused morphological damage and eventually inhibited S. aureus growth. E. elephantina managed to inhibit the growth of bacteria that are prone to drug resistance, which are eventually classified as MDR. The results obtained from this study indicate that the plant has potential as an antibacterial agent
Development of a Multi-Objective Optimisation Model for Mitigating Frequency Instability in a Renewable Energy-Sourced Power System
Full text linkThesis (Doctor:Engineering: Electrical Engineering)--Central University of TechnologyThe power grid is changing in order to reduce the negative effect of greenhouse gas emissions from thermal generators while meeting the global net zero emission goal by 2050. Conversely, as the drive towards a renewable energy-dominant grid is propelled, the overall system inertia of the power grid declines, which causes frequency instability in the modern power grid. This study aimed to develop a multi-objective optimisation model for mitigating frequency instability in a renewable energy-sourced power system. This was achieved by firstly reviewing the various types of virtual inertia control strategies and topology in the power system while highlighting the inertia requirement of the modern power system. The review revealed that adequate system inertia is required for the modern renewable energy-dominant grid to ensure stability; it should therefore be considered in power system operational and planning optimisation models. A new mathematical model was formulated to maximise the overall system inertia of the grid, while minimising system cost and carbon dioxide (CO2) emissions. The model was developed as a mixed-integer quadratic constrained programming (MIQCP) problem and solved using CPLEX solver in the General Algebraic Modeling System (GAMS). The model was validated using a modified Institute of Electrical and Electronics Engineers (IEEE) 9-bus test system. The results revealed that the developed model achieved higher system inertia than the conventional model, which does not consider the inertia requirement of the grid in planning. Furthermore, the model was extended to consider possible expansion in the transmission network as more renewable energy generators (REGs) are integrated into the grid, while considering the inertia requirement of the grid. A new mathematical model was formulated as an MIQCP problem and solved using CPLEX solver in GAMS. To combat declining inertia and mitigate frequency instability in the modern grid, appropriate inertia constraint was introduced into the planning model. Also, an emission reduction initiative (ERI) was introduced in the joint generation and transmission expansion planning (GTEP) model in which power operators were incentivised if they are able to maintain a preset emission limit. The results revealed that the developed model achieved a 24% increase in system inertia and a 9.62% reduction in CO2 emissions. This shows the effectiveness of ERI constraints in meeting the goal of emission reduction in the power system. Furthermore, sensitivity analysis of feed-in tariff (FiT) (economic incentive) was considered in the model. A novel FiT and inertia-integrated GTEP optimisation model was developed, which considered the influence of an economic incentive (FiT) in promoting the integration of REGs into the grid while meeting the inertia requirement of the grid. The model was developed as an MIQCP model to minimise the total system cost and CO2 emissions, while maximising the overall system inertia and FiT incentives. The developed model was implemented on an IEEE 6-bus test system and solved using CPLEX solver in GAMS. Sensitivity analysis of the model revealed that the higher the penetration of renewable energy sources (RESs), the higher the total system cost and total FiT received; however, the fraction of FiT payments received relative to the total investment cost decreased after 50% RES penetration for the same FiT rate. Finally, the model was extended to consider the uncertainties of renewable energy resources (RERs) and system inertia. The intermittencies of wind speed and solar irradiance were addressed using a scenario-based approach. The variability of RER (solar irradiance and wind speed) in the Mangaung Metropolitan Municipality in the Free State province of South Africa was considered for the year 2019. The model was further developed as an MIQCP model to minimise system cost of energy (CoE) while maximising system inertia. The model was solved using CPLEX solver in GAMS and implemented on an IEEE 6-bus system. The model analysis results revealed that considering both system inertia and renewable energy uncertainties provides appropriate planning results with a notable 9% reduction in the total system cost and a 7.9% reduction in the CoE, while the overall system inertia is enhanced by 7.3%. In addition, January was revealed as the best-performing month for wind resources, while October was revealed as the best-performing month for solar resources at the study location (Mangaung Metropolitan Municipality in the Free State). These results show the importance of considering system inertia in power system optimisation modelling to ensure the frequency stability of the modern grid with high penetration of renewable generators is not compromised
Developing a protocol for collaborative decision-making in a smart manufacturing environment
Full text linkThesis (Doctor: Information Technology)--Central University of TechnologyThe Fourth Industrial Revolution places different rapidly advancing technologies like the Internet of Things (IoT), Internet of Services (IoS), Internet of Everything (IoE) and Cyber Physical Systems (CPS) at the centre of developing autonomous manufacturing systems. The development of these systems within the environment of Industry 4.0 expects significant changes in tasks and demands on the human in the manufacturing process and recognises that humans and machines are homogeneous parts of a larger diverse body consisting of collaborative and autonomous components. According to the Industry 4.0 concepts, all objects in the manufacturing world have assimilated processing and communication capabilities which highly affect machine-tomachine communication. However, a considerable consequence is that of the effect it will have on human-to-machine interaction. It is occasional that automated systems are solely autonomous; a level of human interaction is usually present although this challenge is not always considered. In mixed environments, automated systems and humans need to collaborate for the completion of a process. Currently, there exists very little research on how a collaborative decision-making process can be developed such that the worker’s acceptance and adaptation to the process is taken into cognizance. This research identifies the lack of collaborative decision-making processes as a research gap and introduces the problem with an extensive literature review that focuses on the research done in this field, followed by a review of potential models for human technology interaction. A case study of an automated water bottling plant to advance the study in collaborative decision-making is introduced for the execution of several experiments to compare a fully automated approach versus a collaboration between the human operator and the system. A single group experimental approach is used to prove the theory while also identifying where the human will best fit into the automated procedure resulting in an optimized production process. The hypothesis is that the completion time for customer orders will be optimal when the human and the machine collaborate for the completion of the production process
Performance assessment of a ti6al4v(eli) light aircraft nose wheel fork produced through laser powder bed fusion
Full text linkThesis (Master: Engineering: Mechanical Engineering)--Central University of TechnologyA scaled-down nose wheel fork for a light aircraft was redesigned by applying topology optimization for manufacturing in Ti6Al4V(ELI) through laser powder bed fusion (LPBF). This scaled-down nose wheel fork was built together with the test specimens for tensile and fatigue testing in this study. The test specimens were quality checked, tested, and analyzed through standard procedures to obtain the porosity levels, tensile and fatigue properties, and fracture characteristics. The effect of the inherent surface roughness on the high-cycle fatigue properties of LPBF Ti6Al4V(ELI) test specimens was investigated. These test specimens were built to the standard geometry without subsequent machining in three orthogonal directions. They were tested under constant load in a tension–tension fatigue testing machine in accordance with the ASTM E 466 standard. The data was collected and complied with the ASTM F3001 – 14 standard for additive manufacturing (AM) Ti6Al4V(ELI) with laser powder bed fusion. The fatigue performance of the Ti6Al4V(ELI) specimens built to the standard geometry without subsequent machining was compared to that of machined test specimens. It was found that the inherent surface roughness of the specimens built to the standard geometry reduced their fatigue life by about half that of the machined specimens. A customized jig was designed and manufactured to simulate the operational conditions applicable to the scaled-down nose wheel fork. This jig allowed three critical load cases to be tested. The experimental results of the fatigue test specimens and the performance testing of the scaled-down nose wheel fork under static loading were used to evaluate the feasibility of LPBF for production of structural aircraft components, particularly the nose wheel fork. Based on the outcome of the study, it was concluded that it would be justifiable to build a fullscale prototype of the nose wheel fork for testing under operational conditions
The impact of necessity entrepreneurship on the survival of hair salons in Mangaung metropolitan area
Full text linkThesis (MPhil: Business Administration)--Central University of Technology, 2023Despite the South African government’s effort to reduce unemployment, joblessness continues to increase. Some jobless people establish their own businesses in the face of adversity. Out of necessity and desperation, jobless people venture into establishing their own businesses despite the fact that they might not have the relevant resources. Often they lack funds. They venture into own business to accumulate money for survival purposes. One such business that has proliferated out of necessity are small hair salons. Many see this as quick and easy to initiate and run. However, no empirical evidence has been confirmed yet to substantiate the rationale for establishing hair salons and the impact thereof on the survival of the business.
The objective of the study was, therefore, to establish whether hair salon owners start their businesses out of necessity or opportunity in the Mangaung Metropolitan area.
Drawing from a positivist approach, this study adopted a quantitative research design with a sample size of 144 salon owners. A structured questionnaire with standardised questions was used to collect data. The findings show a statistically significant relationship between necessity entrepreneurship and business creation, business stakeholders and business creation business stakeholders and business survival and a minimal relationship between necessity entrepreneurship and business survival. The study concludes that necessity entrepreneurship is moderately related to business survival. The main recommendation is that necessity entrepreneurs need relevant information on small service business to achieve success. It is also recommended that government establish programs to support SMMEs by supporting innovation in small businesses and tax transparency
Assessment of indirect estimation methods to extend observed stage-discharge relationships for above-structure-limit conditions at flow-gauging weirs
Full text linkThesis (Masters: Engineering: Civil Engineering)--Central University of TechnologyStreamflow is seldom directly measured; instead, the stage (flow depth) is
continuously measured and converted into a discharge using a stage-discharge
(SD) rating curve (RC) at a flow-gauging weir or specific river section. During flood
events, flow-gauging weirs might be flooded with the water level beyond the gauging
weir's designed measuring capacity, also referred to as the structural limit of the
weir. Subsequently, the standard calibration of the flow-gauging weir will no longer
be a true reflection of the actual discharges that occurred during the flood events,
and the standard SD RC must then be extended beyond the highest stage reading
to reflect these high discharges at above-structure-limit flow conditions. Direct
measurements, e.g., conventional current gaugings, are also not always possible
owing to various practical constraints associated with these high discharge events.
As a result, various indirect methods for extending SD RCs are available; however,
the impact of using these different methods varies significantly and highlights the
need for a robust and reliable extension method.
The overall aim of this research is to assess and compare a selection of indirect
extension methods (e.g., hydraulic and one-dimensional modelling methods) with
direct extension (benchmark) methods (e.g., at-site conventional current gaugings,
hydrograph analyses and level pool routing techniques), in order to establish the
best-fit and most appropriate SD extension method to be used in South Africa. As
pilot case study, 10 flow-gauging sites in the Free State, Gauteng, KwaZulu-Natal,
Limpopo, Mpumalanga, and the Western Cape provinces were selected based on
the range of possible site conditions present, e.g., type of flow-gauging weir, at-site
and river geometry, flow conditions, type of hydraulics controls, and data availability.
The following hydraulic methods were considered and applied at each site:
(i) Simple extension (SE), (ii) Logarithmic extension (LE), (iii) Velocity extension
simple approach (VE-SA), (iv) Velocity extension hydraulic radius approach (VEHRA), (v) Velocity extension Manning’s approach (VE-MA), (vi) Slope area method
(SAM), and (vii) Stepped backwater analysis (SBA). In addition, one-dimensional
modelling (1-D) was conducted using the Hydrologic Engineering Centre River
Analysis System (HEC-RAS). Data were collected based on the hydrometric and geometric requirements for the
extension of SD relationships. The processing of the geometric data, e.g., wetted
perimeter, wetted area, and hydraulic radius, was done using the Windows CrossSection Professional (WinXSPRO), which is essentially a channel cross-section
analyser. All the SD extensions were executed in the Microsoft Excel environment
using semi-automated tools. The indirect extension methods’ results were
compared and independently assessed against the direct SD measurements or
estimates at each site by using a ranking-based selection procedure based on a
selection of goodness-of-fit (GOF) criteria.
In considering the overall GOF-based rankings, the SBA, SAM, and 1-D HEC-RAS
steady flow modelling were identified as the most appropriate indirect estimation
methods to reflect the hydraulic conditions during high discharges at a flow-gauging
site. The other indirect extension methods were characterised by larger statistical
differences between the at-site benchmark values and the modelled values. The
VE-MA and SE methods are regarded as the least appropriate methods. In general,
any extension method must be hydraulically correct if it is to be used as a robust
approach to extend SD RCs beyond the structural limit. The extension of a RC is
significantly more affected by the site (and river reach) geometry, initial hydraulic
conditions, flow regimes and level of submergence at high discharges than the
actual extension method used. Hence, there is no one-size-fits-all approach
available for the extension of SD RCs in South Africa.
By improving the quality of all input data and assigning more appropriate roughness
coefficients, in conjunction with the implementation of new or alternative SD
extension methods, the improved extension of SD RCs is warranted to result in
consistent and acceptable results. Consequently, the improved and extended RCs
will result in improved hydrological data sets, all of which, will contribute towards
enhanced operational water resource planning, management, and allocation in
South Africa. The recommendations for future research are towards the review of
the current procedures used to estimate roughness coefficients for flash floods, and
the consideration of alternative methods to extend SD relationships, e.g.,
hydrodynamic models, support vector machines (SVMs) and artificial neural network
(ANN) methods
Enhancing spatial image datasets for utilisation in a simulator
Full text linkThesis (Master:Engineering:Electrical Engineering)--Central University of TechnologyThe introduction of Google Street View, which is an integral part of Google Maps, has brought to the surface a method of roof-mounted mobile cameras on vehicles. This is regarded as one of the highly known and adopted methodically for capturing street-level images. Computer vision as one of the frontier technologies in computer science has allowed for the use of building artificial systems to extract valuable information from images. This approach has a broad range of applications in various areas such as agriculture, business, and healthcare.
This dissertation contributes to the development and implementation of Image-Based Rendering (IBR) techniques by presenting a method that makes use of hexagon-based camera configuration for image capturing. Upon the image capturing, each segmented image was stored in a specific folder relative to the camera number. Following this process, the images were chosen based on their timestamp and GPS coordinates and copied to a master folder where the rendering took place.
However, before rendering can take place, the master folder was called inside Blender software. The reason for placing the master folder inside Blender3D was to ensure smooth blending of different image datasets with fewer resources and low computing power during the rendering process. This is feasible as all the image datasets are in one folder as compared to the calling of multiple datasets from different directories which might affect the processing power. Subsequently, OpenCV algorithms were utilised for the Structure from Motion and points of cloud simulation. These techniques and algorithms were based on the available image datasets that were created in the master folder.
Following the optimal image rendering, a process of image blending took place inside the Blender3D software where the captured images (dataset) were rendered for utilisation in the simulator. The use of the Structure from Motion algorithm was utilised for the development of the dense point image, feature, and matching detection. Furthermore, the process for extraction of a depth map model from the three-dimensional (3D) mesh was also highlighted as well as the image restoration process utilising the 3D warping approach. In addition, after these processes were completed, the IBR technique was utilised again for rendering the scenes from the multiple datasets that were captured from the Hexagon Camera Configuration Model to present a scenery that can allow for bidirectional movement. It is therefore noted that the entire work done in this dissertation was substantiated using simulations, genuine data, and physical analysis based on the physically gathered raw data and results from the analysis. The study objectives were therefore achieved by presenting a framework that allows for virtual driving and bidirectional movement of the scene from a Hexagon Camera Configuration Model. Furthermore, the image datasets showed an improvement in the visuals, spatial details and quality of the panoramic images for location identification based on GPS coordinates. Additionally, the rendered images were observed to be smaller than the originally captured images.
The study contribution was based on the GPS module which was utilised to observe and project the scene altitude and coordinates. Moreover, the contribution results process allows for free movement within the 3D-rendered scene to allow for back and forward motion as compared to a slide show that only allows for forwarding motion. In evaluating the efficacy of this research study, the objective argument highlights that through the use of a Hexagon Camera Configuration Model, the user is permitted to move in both the forward and reverse direction within a simulator as opposed to the one-directional movement. These results demonstrate the feasibility of utilising an alternative model for image capture as opposed to the utilisation of a 360o omnidirectional camera and image stitching protocol. Furthermore, the study results demonstrate that the more the input image data, the higher the realism of such a model. In contrast, for 364 image datasets, the output scene is high as a result of a large number of input image datasets with the scene realism observed for both points of cloud and mesh-based on 106110 points
The effect of various clay nanoparticles and their synergy on the properties of polylactic acid for advanced applications
Full text linkThesis (Master: Health Sciences)--Central University of TechnologyThe study investigates the effect of clay(s) on the properties of the poly (lactic acid) (PLA). Nanocomposites having 3% of clays (viz. halloysite, montmorillonite (MMT), and kaolin) were fabricated using melt mixing method. Furthermore, zinc borate was added into the PLA/Clay(s) nanocomposites with the aim of enhancing the properties of nanocomposites. Techniques such as the transmission electron microscopy (TEM), X-ray diffractogram (XRD), thermogravimetric analysis (TGA), rheology, and UL-94 were adopted. TEM was used to investigate the dispersion of the clays within the PLA polymer matrix. The incorporation of the MMT into PLA resulted into an intercalation and exfoliation of the nanoclay within the polymer matrix when compared with kaolin and halloysite clays. As the ZnB was not modified, its nanoparticles were found to be agglomerated into the PLA matrix. Furthermore, the synergy of the other clays with MMT seems to have formed intercalation and exfoliation, which seems to verify that MMT acted as a modifier for other clays within the PLA matrix. It was further observed that the presence of ZnB and clays such as halloysite, and kaolin clays resulted in immiscibility between the nanoparticles and the PLA matrix. According to the XRD, the incorporation of the MMT in the PLA systems acted as a steric hindrance; and as a result, crystallization was restricted, thus causing a reduction in the intact crystalline region. Thermal stability of the tubular halloysite clay-based nanocomposite was found to be higher when compared with the silicate clay-based nanocomposites (viz. MMT and kaolin). One can realize that the synergistic effects of the nanoclays showed better thermal stability than all the single clays reinforced PLA matrix. Additionally, the majority of the synergistic nanoparticles were found to have a high thermal stability when compared with single filler-based nanoparticles/polymer composites. Halloysite in the PLA/ZnB system improved the complex viscosity of the system more than all the clays systems and PLA due to a stable and tubular structure of the halloysite. Halloysite, and its synergy with the other clays seemed to dominate in terms of improving the flammability resistance of the PLA matrix with V-0 UL-94 rating. The pollutant removal efficacy was found to be depended on the filler-type. Fillers with stronger interaction with PLA resulted in poor adsorption properties due to limited accessibility to the available active sites