Theses and dissertations (Engineering and Built Environment)
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Item Fabrication and analysis of nanoparticle-infused natural fibre honeycomb core in sandwich structures(2024-05) Govender, Sumeshan; Kanny, Krishnanhis study investigates the feasibility of employing natural fibre materials to fabricate honeycomb core structures, addressing concerns over the environmental impact associated with conventional cores composed of aluminium, Nomex, and petroleum-based materials. The research process involves the fabrication of honeycomb cores utilizing a 3D printed moulding technique, followed by the adhesion of these cores to flax and glass fibre facings, thereby augmenting structural durability. Through the incorporation of cellulose and nanoclay as additives to the adhesive, the investigation reveals a substantial enhancement in flexural strength and impact resistance, surpassing the performance of structures bonded solely with epoxy. However, a notable reduction in compressive strength is observed upon the introduction of these additives to the adhesive. Quantitatively, the study demonstrates that the addition of 3wt% cellulose to the epoxy adhesive results in a remarkable 7.43% increment in flexural strength, a 4.09% increase in yield stress, a 0.17% rise in flexural modulus, a 6.45% enhancement in core shear ultimate strength, a 7.17% increase in facing bending stress, and a 7.94% elevation in absorbed energy. Similarly, the addition of 3wt% nanoclay to the epoxy leads to a significant enhancement, with a 10.48% rise in flexural strength, a 4.09% increase in yield stress, a substantial 20.92% augmentation in flexural modulus, a 10.75% improvement in core shear ultimate strength, a 10.5% increase in facing bending stress, and an elevated absorbed energy by 14.37%. Furthermore, in out-ofplane oriented structures, ultimate compressive strength experiences an increase of 7.32% and 20.1% for cellulose and nanoclay additives, respectively, while compression modulus rises by 6.6% and 29.65%. Nevertheless, it is noteworthy that the structures bonded with nanoclayfilled epoxy exhibit the most favourable overall performance, boasting an ultimate compressive strength of 7.72 MPa and a compression modulus of 7.77 MPa, outperforming their in-plane counterparts due to the larger compressive area of the out-of-plane samples. In terms of tensile properties, the study establishes that hybrid face sheets display an impressive 33.65% higher ultimate tensile strength compared to plain flax fibre samples. Additionally, the hybrid face sheets manifest a 69.45% increase in tensile strength and a substantial 58.73% enhancement in yield stress and Young's modulus, respectively, in contrast to exclusively flax fibre facings. Moreover, the research indicates that hybrid face sheets lead to significantly reduced moisture absorption, with structures employing solely flax fibre face sheets experiencing a mass increase of 11.88% after 168 hours of exposure, while structures utilizing hybrid face sheets encounter a substantially lower mass increase of 6.31%. This corroborates the effectiveness of hybrid face sheets in enhancing the water resistance properties of the composite. In summation, the study underscores the potential of natural fibre honeycomb composite structures to perform comparably to traditional honeycomb materials such as Nomex and aluminium, while being constructed from environmentally sustainable materials. The integration of an efficient additive manufacturing process further bolsters the prospects of these structures, enabling customization and scalability for diverse applications across industries, including aerospace, automotive, and marine sectors.Item Development of integrated model and framework for sustainable energy resources and systems planning(2024-05) Akpan, Joseph Samuel; Oludolapo, Olanrewaju AkanniSustainable energy development (SED) is a crucial component of the Sustainable Development Goals (SDG), aiming to maintain economic and social progress while protecting the environment and mitigating climate change's effects. SED serves as a transition paradigm for sustainable development, providing a blueprint for energy peace and prosperity for people and all uses. The first objective of this dissertation is to identify 10 interlinked themes of SED and explore 2 of them, which are the least studied in existing SED reviews. These two themes include energy financing and commitment to climate change and the need for 100% renewable energy (RE), a part of the decarbonization strategy towards the 1.5 - 2.0 °C Scenario. The study suggests that the current G20 countries' contributions, if done continuously per annum, in addition to 80% more funding from private investment of the same amount in the 1.5°C scenario financial requirement for clean energy, is sufficient to limit global warming. In addition to the present drive for 100% RE for all purposes, an emphasis is placed on addressing other issues, such as energy storage options, developing countries' development agenda, and regional security stability to prevent energy wars. Emerging SED decarbonization strategies are presented across power, transport, building, and industrial sectors. This part concludes with a summary of SED progress and directions for future research, mainly the need for re-defining Nationally Determined Contribution (NDC) through a centralized global or regional stock-taking strategy for greenhouse gas emissions reduction. Consequently, the next study attempts to address the limitations of the current NDC by formulating a policy hypothesis and applying it to an integrated assessment tool (here, termed the environmental model) for strategic stock-taking in reducing GHG emissions. In developing this indexing model, being the first objective of this thesis, we analysed the potential impact of Nationally Determined Contributions (NDCs) under the Paris Agreement on global temperature rise used as the key model input parameters with countries' historical data and other parameters such as GDP, population growth. With the use of an integrated assessment tool based on the concept of system dynamics, the analysis constructs a framework to project global temperature changes under five policy scenarios, namely baseline, current (announced energy policies 1 and 2), and optimum (2.0 0 C Scenario), and most optimum (1.5 0 C) case scenarios. The hypothesis is formulated based on the analysis of current, announced, and best-case global and or applicable national policy scenarios. The model aims to address critical questions regarding the effectiveness of the on-going NDCs commitments in limiting global temperature rise to well below 2 0 C, in alignment with the Paris Agreement's goals. The simulation results offer a roadmap for optimizing the current NDCs in global and national energy policies and treaties, fostering international collaboration, and reinforcing the global commitment to combating climate change. Leveraging on the preceding simulation result of the environmental model, a novel emissions budgeting (EB) model tool (here, termed the economic model) was introduced as a simplified approach for the determination of the economic attractiveness of the policy scenarios of the environmental model. Hence, the second objective, which was to determine the economic benefit of policy scenarios, was achieved. Some advanced countries’ rapid population, economic growth, and energy consumption from mostly 100% electricity that is majorly fossil-based contributes significantly to global CO 2 emissions. In contrast, the case in most developing countries is different. For instance, electricity access in Africa is less than 60%. Hence, this presents challenges and opportunities for achieving the United Nations’ Sustainable Development Goals (SDGs) 7 and 13 of generating all energy from cleaner or low-carbon sources to reduce CO 2 emissions in all countries and combating climate change consequences. Therefore, considering the peculiar situation of other developmental goals, such as increasing population access to electricity while being obliged with the need to transit to complete renewable energy, as our third objective, we explored the idea and transition paradigm of reaching a 100% renewable energy that is void of unjust energy transitioning, climate injustice, and unbiased drive for increasing renewables energy penetration in the global energy mix. The increasing need for renewable energies has been widely acknowledged to greatly advance the climate change agenda as increasing clean energy usage depletes the accumulation of GHG in the atmosphere. Alongside reducing the accumulation of GHG, increasing RE share in the national mix has constantly become the core of many countries' energy policies and the agenda of many of the NDCs reported by countries. Presently, about 30 countries already with over 70% of their national electricity mix from RE. A part of this has birthed a new paradigm and an emerging field of 100% RE for all purposes, recently receiving much attention from academia and in public discourse. Upon establishing the need for analysing the transition towards 100% RE, the thesis demonstrated this conceptual idea through a model (here, termed the energy model) to analyse the possibilities for a 100% renewable energy system at the global level. Because several studies have already done such analysis, however, this has hardly been directly linked to the climate scenarios. Therefore, this thesis bridged this gap in the literature by synthesising the energy transition at different percentage shares in the global primary energy mix over time with the effect on global temperature levels. The rationale behind this was to present a discussion on the pathway possibilities and challenges of achieving 100% RE and whether it is possible to meet the total global energy demand through RE, with what effect on the climate scenarios. To do this analysis, we further define our hypothesis using baseline, optimum, more optimum, and extreme optimum path scenarios to ascertain such possibilities. Finally, we used an integrated assessment model based on the principles of system dynamics to analyse these hypotheses and to find the implications of each action or scenario on other factors such as global temperature, GHG emissions, energy storage breakthrough while keeping the population growth at maximum possible value of 12.4 billion persons by 2100 with GDP growth rate not less than 1.5%. The findings are valuable in helping us discuss if 100% RE can be a reality and what the implications are. Our results show that in the baseline current scenarios, the global average temperature will most likely be kept at 3.3 0 C. Hence, the world would need very urgent and unprecedented efforts beyond the current baseline of business as usual. Interestingly, our findings also indicate that to stay within the 1.5 and 2.0 0 C Scenarios, the world may need just between (58.6 - 77.3) % and (62.7 - 82.8) %, respectively, in the global energy mix. For the most optimistic scenario, (75.5 - 99.8) % RE may be required, and this is able to keep the temperature rise even well below 1.5 0 C but at 1.1 0 C. The 1.1 0 C possibility is quite highly ambitious, in my opinion, because it requires the intensity of global mix energy generation of about 6627 extra joules from renewables only. The major challenge with the idea of 100% RE for all purposes is that achieving such a feat requires a more diverse approach and scarcely are there 100% RE studies that incorporate holistically the interrelation of several pertinent strategies. Therefore, there exists a need to meet both the technical and non-technical requirements. In order to address this shortcoming, our third objective introduces six methodological or evaluation mechanisms (herein, identified as 100% RE evaluation metrics) suitable for existing and future 100% renewable energy analysis. It then reviews energy modelling tools to identify their applicability to 100% RE analysis. The perspectives presented in this thesis are valuable in developing a common integrated methodology and modelling tool for analysing full renewable energy adoption in countries or regions with best trade-offs, using performance indices that have not been previously used. The proposed metrics could also help with proper national and regional energy resources and system planning for new energy projects and installations, contributing to sustainable development. The framework and narrative, presented in the form of a model within this dissertation, make a noteworthy contribution to the ongoing discourse surrounding the energy transition as, to the best of my knowledge, this concept has not been presented this way. The results from this dissertation can be further investigated through a streamlined application of the approach at individual country or regional level to facilitate inclusive and climate-responsive planning and execution strategies for sustainable energy and electricity generation, distribution, and utilization at both national and urban levels. The implications of the findings have the potential to inform the United Nations Framework on Climate Change Convention (UNFCCC) and Conference of Parties (COP) policies in better ways of promoting equitable support for countries, regions, energy consumers, utilities, and prosumers.Item Shifting territories : towards a methodology for a creative emancipatory approach to place-making, the role of Spaza shops in Cornubia, Blackburn, KZN(2024-05) Jahangeer, Mohammud Anwar Noorani; Erwin, KiraThis research argues that the idea of a ‘breaking new ground’ initiative in urban planning demands the effort of unearthing existing alternative practices and attitudes in the pursuit of spatial justice (Soja 2010). The study is located in Cornubia, a large human settlement development on the north coast of KwaZulu-Natal, Durban, South Africa. Contextualised within the national landscape of state-housing provision, and the theoretical lens of place-making and spatial justice, it aims to offer both theoretical and practical insights into the gap between theory and practice in current participatory practices in planning and housing. It explores how creative methodologies may be useful mechanisms for participatory planning, especially in facilitating and translating how residents in housing developments make meaning out of the places they live in. It engages how these may differ, or not, from meaning-making done by state planners and officials. To demonstrate the argument, the thesis uses the example of spaza shops both as a metaphor and a popular initiative. Following on, it suggests that spaza (as creative impulses) owners could take the form of interlocutors who can facilitate dialogue between official top-down planning and quotidian bottom-up operations within the context of the Cornubia development. In doing so, the potential for dialogue in a creative form that already exists ‘informally’ as the popular innovations/manifestations exemplified in the spaza shop, can be revealed. It is in the interstitial space of misunderstanding, where communication often breaks down between the state and the street, that this research has positioned art/creative practice as a way of opening up dialogue within and between individuals, communities, and the state. In addition, arts-based/informed methods, including the use of drawing, Lego blocks, image theatre (drama), and Scrabble are employed as data-generating tools. Furthermore, workshops, focus groups, and face-to-face interviews are conducted to reflect, articulate and reveal the experience of the participants living in a human settlement and their understanding of space and urban planning. The thesis also draws on a series of interviews with the built environment specialists involved both directly and administratively in the project. The objective is to explore the potential for the conceptualisation of powerful catalysts for transformative forms of politics and for providing new sets of resources for urban and spatial thinking Theoretically, the dissertation argues that spazas should be read as popular culture since popular culture is both evasive and resistant (Fiske 1989) and is created “out of the resources, both discursive and material that are provided by the social system that disempowers [the people]” (Fiske 1989:2). Spazas are creative impulses in their own right, developed organically, as critical responses to an environment which has limited access and spaces for the working-class and poor to exercise their various freedoms whether they be economic, spatial, social or cultural.Item Design and application of passive filters for improved power quality in standalone PV system(2024-05) Dlamini, Sandile; Adebiyi, Abayomi Aduragba; Kabeya, MusasaHarmonic components have developed in power systems due to the non-linear properties of the circuit components utilized in power electronics-based products and their rapid application. Power systems rely on fundamental quantities like sinusoidally varying voltage and current, which oscillate at a frequency of 50 Hz. The standard restrictions of IEEE-519-1992 were utilized as a benchmark in this study. To generate the best output, the total harmonic distortion (THD) should be decreased below the limit, even for certain individual harmonic numbers, and reflect the power factor output. Using the results of the simulation and projections for each mitigation strategy, the THDI can be reduced below the IEEE-519 standard whilst also providing cost and electrical advantages. Analysed and modelled is the PV system, which comprises solar panels, a DC-DC converter, a DC-AC inverter, and a non-linear load. Passive filters are an effective solution for improving power quality in standalone photovoltaic (PV) systems. This dissertation provides an overview of the design and application of passive filters for this purpose. Firstly, an introduction to PV systems and the power quality issues associated with them was preferred. Next, different types of passive filters, namely LC filters, LCL filters and LLCL filters, are discussed along with their advantages and disadvantages, and the design considerations for these filters, including the selection of filter components and the calculation of filter parameters. The application of passive filters in standalone PV systems was then discussed, including their implementation in DC-DC converters and Z-Source inverters and, the design of PWM controllers such as the constant boost control method and simple boost control method. The analysis of the outcome of the engineered systems was conducted according to the IEEE standard and SANS 10142 Standard to protect the connected equipment within the off-grid network. The outcomes pertain to the single-phase stand-alone/off-grid photovoltaic system and the single-phase Z-Source inverter. The Z-Source inverter is equipped with two distinct methods for PWM control, namely the constant boost control method and the simple boost control method. All three designs incorporate three passive filters, namely the LC filter, the LCL filter and the LLCL filter. The results were obtained from the network consisting of three distinct designs. LLCL demonstrates superior performance as a passive filter, substantiating its position as the optimal choice. The optimal outcomes of a single-phase off-photovoltaic (PV) network can be achieved using LC, LCL and LLCL filters, with corresponding percentages of 2.99%, 2.45% and 1.71% respectively. Unfiltered was 89.05%, which is not good for the equipment connected to the network. The Z-Source showcases the capability of voltage amplification to an infinite level, rendering it highly effective in minimizing total harmonic distortion. This research investigation further demonstrated the efficacy of the Z-Source Inverter with Constant Control Boost Method and Simple Boost Control Method, achieving unfiltered total harmonic distortion levels of 38.85% and 44.96% respectively. The Z-Source inverter, when combined with the Constant Boost Control method and Simple Boost Control method, exhibits various filter configurations such as LC, LCL, and LLCL filters. In the context of the constant boost control and simple boost control methods, it is imperative to assess the total harmonic distortion percentage of voltage and current for LC, LCL, and LLCL configurations. The constant boost control voltage (LC, LCL, LLCL) and current total harmonic distortion (LC, LCL, LLCL) are measured at 4.177%, 2.655%, 1.951%, and 2.958%, 2.09%,1.465% correspondingly. The voltage-based boost control methods, namely LC, LCL and LLCL, exhibit total harmonic distortion levels of 2.345%, 1.920% and 0.211%, respectively. Similarly, the current-based boost control methods, LC, LCL and LLCL, demonstrate total harmonic distortion levels of 2.346%, 1.921%, 0.211%, and 2.346%, 1.921%, 0.211%, respectively. Finally, the dissertation wrapped up by exploring the potential of passive filters for enhancing power quality in standalone PV systems. The thesis offers a comprehensive investigation of the design and implementation of passive filters in standalone PV systems, providing valuable insights for engineers and researchers in the field. It enhances understanding and utilization of these imperative devices.Item Optimization of water distribution networks : a digital approach(2024-05) Mongwe, Regionald; Telukdarie, Arnesh; Rathilal, SudeshWater stands as the fundamental cornerstone of life, and with the human population growing exponentially, the critical importance of sustainable water management becomes increasingly evident. Water not only serves as the essential working fluid for major chemical processes, including thermal energy generation, but it is also integral to manufacturing and domestic use. Despite its significance, water is a scarce commodity, and the planet continues to lose this precious resource due to theft, pipe bursts, and leakages in water distribution networks (WDNs). The consequences of water loss extend beyond the impact on physical resources, as it is intricately linked to financial challenges. Thus, water loss has the potential to result in substantial financial setbacks for companies, organizations, and government entities, underscoring the interdependence of water management and fiscal sustainability. In response to these challenges, digital technologies have been harnessed to optimize WDNs. A major constraint lies in deciphering the applicable digital technologies due to the multidisciplinary nature of the research area encompassing WDNs and digital technologies; therefore, this study adopts a systematic literature review (SLR) combined with digital tools, to comprehensively extract all aspects of a WDN, ranging from sensors to enterprise resource planning (ERP), including equipment and systems. This literature forms the foundational basis for constructing a framework aimed at creating a content repository for digital WDN sustainability. To further develop the framework, this study reviews international best practices in digital WDN. This is adopted in developing a digital WDN framework based on the literature and classifying a database structure from sensor to ERP for a generic WDN. Furthermore, the study explores tools and systems for optimization as well as updating the theoretical structure with Johannesburg WDN data and provides a comprehensive evaluation for enabling digital WDN in South Africa. The digital WDN framework comprises three distinct components: security, a central management database (CMDB), and best practice architecture. The architecture involves five layers, including the physical layer, communication layer, data storage and analysis layer, benefit layer, and application layer. Utilizing systematic literature review and bibliometric keyword analysis, the study determines the equipment, systems, and their uses, leading to the development of a generic WDN. Validation of the framework using the generic WDN emphasizes the equipment and systems used in each of the five layers. Furthermore, the framework is validated using Johannesburg Water's WDN, leading to the development of a CMDB. The CMDB underscores the possibility of storing physical layer and communication layer configuration items (CIs) and highlights asset management, CI relations, change management, and historian capabilities. Maintaining an accurate and updated CMDB necessitates employing asset discovery solutions, while CMDB relationship mapping plays a crucial role in assessing the ripple effects of CI changes within a complex system. Finally, the measurement of the digital maturity of Johannesburg Water's WDN using the Administração e Gestão de Sistemas de Salubridade (AGS) maturity index reveals a maturity index of 62%. The index emphasizes strong capabilities in GIS integration and data collection through the SCADA system. Despite advancements in planning systems, such as domestic flow metering, there remains an opportunity to enhance asset management capabilities for continuous improvement in WDN operations.Item Sustainable construction through the implementation of post-occupancy evaluation practices : a case study of RDP buildings in Mpumalanga(2024-05) Simelane, Nkuthalo John-Junior; Mewomo, Modupe Cecilia; Okorafor, CAbstract Reconstruction and Development Programme (RDP) buildings in South Africa were promulgated to alleviate poverty and provide better social services for previously disadvantaged South Africans by allocating tax money for development projects. However, there is a growing concern about the quality of housing developed under the RDP programmes. Post-occupancy evaluation is one of the measures that has been proposed to ensure the quality of these buildings is well understood and improved upon. The study sought to investigate the current status of post-occupancy evaluation (POE), understand the barriers to effective implementation of POE, and investigate the critical success factors and the benefits of POE in Mpumalanga Province, South Africa. To achieve this objective, the study adopted a quantitative approach utilising a questionnaire survey to expedite the collection of data, which was then analysed descriptively and inferentially. The study population was purposively selected due to the specific nature of the data collected. Professionals employed by the Department of Human Settlement in Mpumalanga and involved in the construction of the RDP building in Mpumalanga province provided the data. The findings indicate that the critical success factors for effective implementation of post-occupancy evaluation are: participation and commitment; leadership; education and skills; benchmarks and indicators; top management support; availability of resources; POE information management; and effective feedback. With respect to barriers that affect the effective implementation of the POE, the study identified the following: lack of adequate resources; lack of knowledge of POE procedures; lack of awareness of POE; lack of top management support; lack of coordination by departments; lack of owner’s knowledge of POE and benefits; and POE is not integrated into the scope of work of the facility department. The study posited that POE could provide the basis for necessary changes, help increase design know-how, determine building defects, increase building performance, reduce maintenance costs, and increase occupants’ satisfaction.Item Evaluating the removal of emerging contaminants from the eThekwini Municipality REMIX Water Treatment Plant(2024-05) Manyepa, Prince; Bux, Faizal; Seyam, Mahommed; Banoo, IsmailThe eThekwini Municipalities Department of Water and Sanitation (EWS) has initiated feasibility studies to determine whether it is financially and environmentally viable to implement direct potable water reuse (DPR) projects, and one of them is the REMIX Water Treatment Plant (RWTP) which is located within the Port of Durban and abstracts wastewater and sea water for treatment and potential future re-use. However, a review of the extant literature has highlighted that wastewater and seawater are primary sources and "sinks" for various contaminants of emerging concern (CEC). Emerging contaminants (ECs) can be endocrine-disrupting chemicals or cancercausing agents in humans and animals if they are constantly present in drinking water. This study evaluated the efficiency of the RWTP for the removal of different classes of pharmaceutical compounds by measuring the feed water and effluent of each treatment unit along the RWTP. The Quantitative structure-activity relationship (QSAR) model and OPBT criteria were used to screen these compounds for persistence, bioaccumulation, and toxicity (PBT) behaviour in the water matrix. This was done to produce a priority list that allowed effective monitoring of each treatment unit for observed PBT compounds that should not be present in reclaimed water intended for human consumption. The QSAR is a suitable alternative to the costly and labourintensive in vivo screening experiments in the water matrix. It works in tandem with the new animal rights regulations, is safer than laboratory experiments, and also saves time. The study found that 4 out of 20 compounds were identified as potential PBT compounds by consensus agreement in both methodologies. The goal of this study was to assess the removal of ECs prioritised using the QSARINS model and OPBT criteria by carrying out a human risk analysis for reclaimed water proposed for drinking purposes within the City of Durban. This informed decision-makers, plant managers, and operators on what to constantly monitor or add to the treatment plant for the safe production of drinking water. Excellent removal rates of ECs were observed in the membrane biological reactor (MBR) and the reverse osmosis systems (ROs). The removal rates in MBR and ROs ranged from 38% to 100% and 96%, respectively. Excellent removal rates for heavy metals and nutrients across the treatment technology were also achieved in the final product water. The calculated risk/hazard quotients (RQ) for all ECs and heavy metals were also conducted in the reclaimed REMIX water. An RQ/HQ > 1 meant a high risk of ECs or heavy metals, and <1 meant the risk was negligible. Except for some anomalies caused by ion suppression or matrix effects during the analysis, the majority of the ECs in the reclaimed water RQ were found to be less than 1. Identification of chemical, biological, and physical hazards using HACCP system principles led to the identification of critical control points for the technology. Five critical control points were examined, and techniques for successful RWTP monitoring were proposed based on the study findings.Item An investigation of a scalable flight control system for a variable pitch, fuel powered, quad-rotor craft(2024-05) Nielsen, Byron Vaughn Roy; Gilpin, Mark; Ghayhoor, FahzadQuadrotor platforms continue to face scalability issues that can be linked to factors such as energy density of polymer battery power sources and the limited efficiency of their fixed pitch propulsion systems. This study employs a dual-method analysis, integrating both experimental and theoretical approaches, to explore the trade-offs between endurance and payload capacity in a quadrotor equipped with a scalable variable pitch rotor system. By applying this development framework, the key objective of this work is to broaden the scope of feasible mission profiles by clarifying the inherent constraints and compromises between endurance and payload capacity and illuminating factors contributing to efficiency. In this pursuit, the first main aspect focused on empirically validating various rotor geometries using test bench system. Data collected is analysed using the computational tool MATLAB, whereas XFOIL simulates airfoil lift and drag characteristics. Rotor performance is then characterised through comparative analysis between experimental data and theoretical predictions made by the Blade Element Momentum Theory (BEMT) rotor model. From comparisons it was found that the BEMT model performance and behaviour remained consistent at varying rotor geometry scales and correlated well with empirical thrust results. It was also found that approximations for power output levels were marginally overestimated at high blade pitch angles – the possible causes of which are further explored in an article published in parallel to this work. [1] The 6-DOF (degrees of freedom) nature of quadrotors in a dynamic environment is then explored using Simulink wherein a flight control system (FCS) architecture is formulated by integrating control laws with a BEMT rotor model. Comparative performance evaluations focusing on dynamic behaviour, thrust generation, and power efficiency are then realised by subjecting a standardised quadrotor airframe with varying rotor geometry and payload capacities to an idealized climb-to-hover (C2H) trajectory. From comparisons of simulation tests, it was significant to find that varying rotor geometry and payloads yielded highly contrasting dynamic behaviours and efficiency performance in terms of thrust generation and power demands. Simulation data also indicated that the B04 rotor configuration was the most energy efficient and enabled superior climb rates and accelerations. By employing figures for simulated hovering power demands, abstracted endurance times are shown to be greatly affected by the energy density and payload constraints between chemical battery systems and carbon fuels. Comparative analysis of rotor performance also revealed that the choice of hardware configuration may necessitate prioritising durability and responsiveness over efficiency. Moreover, mission profiles optimised for high dynamic responsiveness must ensure that FCS sensitivity does not exceed the strength constraints of mechanical subsystems or airframe structure. Collectively, this work successfully established a robust framework for future research and early-stage development of scalable quadrotor platforms can be achieved by integrating variable pitch rotor systems with modularized quadrotor control system architectures. This framework provided key insights into improving quadrotor performance and efficiency, particularly through scalable rotor geometry and payload capacity.Item Development of a multi-criteria decision-support tool for improving water quality to assist with engineering infrastructure and catchment management(2024-05) Ngubane, Zesizwe; Sokolova, Ekaterina; Stenström, Thor-Axel; Dzwairo, BloodlessResearch combining water quality modelling, quantitative chemical/microbial risk assessment, and stakeholder engagement to prioritise catchment areas facing water pollution problems to devise effective pollution mitigation strategies are limited. This research therefore aimed to address this gap by providing a practical and comprehensive framework that supports wellinformed decision-making processes in water pollution alleviation. By integrating multiple criteria and catchment aspects, this framework can assist infrastructure, operational, and ecological managers within a catchment in prioritising best management practices (BMPs) to reduce pollution and mitigate against potential resultant impacts. Given this context, uMsunduzi catchment, in KwaZulu-Natal, South Africa was chosen as a study site. UMsunduzi River is a major tributary of uMngeni River that is used for water supply to the cities of Pietermaritzburg and Durban. The study begins with the data synthesis from diverse sources of scientific data to identify chemical and microbial hazards, utilising a water quality modelling tool to map point and nonpoint source pollution in the catchment. The assessment encompasses the presence of pathogens such as Cryptosporidium and Escherichia coli (E. coli) in the catchment, with rural areas showing a greater contribution from animal sources, while urban areas are affected by impaired wastewater infrastructure. Quantitative microbial risk assessment (QMRA) was conducted, assuming no water treatment within the catchment. The investigation considered multiple exposure routes, including domestic drinking and recreational activities for both adults and children. The results indicate that the probability of infection from Cryptosporidium and E. coli exceeds acceptable levels set by South African water quality guidelines and the World Health Organization. The assessment further included a chemical risk assessment on various chemical groups, including organochlorinated pesticides (OCPs), pharmaceuticals and personal care products (PPCPs), heavy metals, nitrates, and phosphates. Elevated carcinogenic risks were observed for most OCPs, while noncarcinogenic pesticide effects pose long-term risks. Heavy metals and PPCPs are within sub-risk levels, but phosphates have notable ecological and health impacts, particularly in Inanda Dam, a key source of potable water for Durban. In this study, a unique contribution is made by incorporating both chemical and microbial risk assessment. Furthermore, the risk assessment methodology not only encompasses various chemical pollutants and exposure pathways but addresses the nuanced issue of water consumption variability between children and adults. To address these identified risks, a multi-criteria decision analysis methodology is employed to engage stakeholders in the risk management process. Affected, involved, and interested stakeholders, along with economic, environmental, and social criteria, contribute to the selection of Best Management Practices (BMPs). The Simple Multi-Attribute Rating Technique for Enhanced Stakeholder Take-up (SMARTEST) is utilised to identify suitable interventions. The study culminates in the recommendation of BMPs that aim to change behaviour, including public education on livestock grazing management, safe medication disposal, and responsible fertilizer and pesticide use. Pollution management measures, such as solid waste control and river cleanup, are suggested, along with infrastructure management improvements, like sewer system maintenance. This research strived to bridge the gap in water pollution alleviation by presenting a practical and comprehensive framework designed to support well-informed decision-making processes. This framework, with its integration of multiple criteria and considerations, stands poised to aid infrastructure, operational, and ecological managers within a catchment in prioritising BMPs aimed at reducing pollution and mitigating resultant health impacts.Item Inhibiting carbon dioxide hydrate formation using deep eutectic solvents(2024-05) Ngcobo, Themba Luyanda; Ramsuroop, Suresh; Tumba, Kaniki; Lasich, Madison M.The formation of gas hydrates in pipelines during gas and petroleum extraction processes can result in multiphase systems including gas hydrates. These will form as solids in the presence of water and gas under thermodynamically favourable temperature and pressure conditions. Gas hydrates raise safety concerns, hinder process performance, and impact on financial resources as they block pipelines. The formation of gas hydrates can be efficiently prevented by using certain substances referred to as inhibitors. However, most inhibitors are expensive, potentially dangerous, and damaging to the environment. Hence, there is need to investigate environmentally friendly alternatives to mitigate gas hydrates. The objective of this study was to examine the efficiency of green additives referred to as deep eutectic solvents (DES) in inhibiting carbon dioxide gas hydrate formation. Deep eutectic solvents consisting of Tetrapropylammonium bromide + glycerol (DES-1), Tetramethylammonium chloride + glycerol (DES-2), and Tetramethylammonium chloride + ethylene glycol (DES-3) on carbon dioxide hydrates is investigated. These solvents are worth studying because their synthesis, purification, and environmental friendliness offer economic advantages. Molecular Dynamics (MD) simulations were used to theoretically determine the conditions that promote or inhibit the formation and stability of cardon dioxide hydrates in the presence of the selected inhibitors. The conditions investigated include temperature, pressure, and inhibitor concentration. The use of rigorous computational methods for preliminary screening significantly reduces the cost and the duration of experiments. MD simulation results were further validated using experimental gas hydrate equilibrium data. Results obtained in the present study indicated that the various DES solutions have both inhibiting and promoting effects. It was also found that low concentrations promoted hydrate dissociation, whereas high concentration greater than 0,20 stabilised hydrate formation. Pressure and temperature also impacted on the concentration of the DES solutions that inhibited or promoted hydrate formation. The concentration of the DES solutions shifted the hydrate curve to inhibit or promote hydrate formation.