Masters Degrees (Electrical and Electronic Engineering)

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    Development and evaluation of an electrochemical DNA based magnetic nanoparticle biosensor for detecting the fungal pathogen fusarium oxysporum f. sp. cubense
    (Stellenbosch : Stellenbosch University, 2024-03) Akwuruoha, Uzoma Nobe; Perold, Willem; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: Fusarium wilt caused by the soilborne fungus Fusarium oxysporum f. sp. cubense (Foc), is one of the most detrimental banana diseases worldwide. Foc is pervasive in practically all banana-growing regions and classical management strategies are not effective or economically viable options to control the pathogen. Prevention and containment are therefore vital to limit the spread of the pathogen. Regular and accurate surveillance stands central to the efficient co ntainment st rategy as it ca n in dicate wh ich co urse of action is most appropriate. Presently, the available methods for detecting fungus Fusarium oxysporum f. sp. cubense are limited by complex procedures, high expenses, and prolonged processing times. To combat these obstacles, the proposed research aims to develop a DNA-based electrochemical magnetic nanoparticle biosensor to enable rapid and precise detection of Foc. To this end this project investigates a low-cost DNA-based electrochemical magnetic biosensor for detecting Foc, using linear biotinylated DNA probes bound to streptavidin-coated magnetic beads, immobilised on gold surface screen printed carbon electrode. A squarewave voltammetric-based electrochemical technique was chosen to detect the presence of Foc. A gold surface screen printed electrode was selected as a transducer, with the biotinylated DNA probes bound to streptavidin-coated magnetic beads immobilised on the electrode workspace by a magnetic field. An e lectrochemical potentiostat device was used to electronically detect the change in current peaks resulting from the electrochemical reduction and oxidation reaction of DNA samples after immobilisation on the biosensor system.
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    Research and development to produce a first generation running power measurement device
    (Stellenbosch : Stellenbosch University, 2024-03) Brink, Lambert; Smit, Willem; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: This research contributes to the engineering and the understanding of power kinetic power measurements while walking or running based on each stride. This research explores ways of applying power measurements through a low-power embedded apparatus placed on the foot. In doing so, the study identifies current marketplace models (not necessarily footbased), refines the measurement of external factors such as spatio-temporal parameters, and identifies the overall accuracy of these models. The methodology, through comprehensive research, proposes an algorithm for implementing a net mass/energy balance equation. This algorithm, applied in its simplest form necessitated the need for a speed (velocity) measurement and subsequently also identified the need for gait measurements, velocity estimation, position estimation and free space orientation measurements. This thesis outlines the measurement and analyses of several spatio-temporal parameters using an embedded foot device. Once applied the parameters are analysed and used to calculate the simplistic kinetic output. The hardware design primarily focuses on the measurement of acceleration, angular acceleration, and magnetic flux, which are essential components of an Inertial Measurement Unit (IMU) device. This is achieved with a simple Microcontroller unit (MCU) accompanied by the integration of data storage with flash memory or a ”Google Sheet” platform. Furthermore, data transmission is processed with a Bluetooth Low Energy (BLE) device. The parameters are then analysed on the device itself, where the orientation is calculated using a quaternion-based implementation. Additionally, filtered acceleration is measured and calculated in gravity free space, ensuring accurate velocity calculations that are free of drift due to the Zero Velocity Update (ZVU) algorithm implementation. Following velocity calculation, position estimation is calculated in conjunction with the gait measurement, enabling the measurement of speed and distance travelled, thus allowing the analysis of a kinetic power measurement using basic motion. Applying the quaternion-based orientation calculation yielded high accuracy, enabling the correct measurement of subsequent parameters, such as the filtered acceleration and velocity. In contrast, gait measurement encountered challenges. Despite its accuracy, it had difficulty capturing data within the data storage segment, leading to various issues. With data and storage segmentation, the gait calculation has improved accuracy with the ability to measure each step. Furthermore, velocity and position estimation were drift free and within 10% accurate compared to the testing methods. Finally, utilising the combined measurements, a speed calculation (distance travelled over stride time) was used, showing promise for achieving a reliable kinetic power result. This analysis indicates that the foot device is capable of generating a relative power measurement on an embedded foot device, provided that it is not obstructed by storage segmentation. The research also revealed that the accuracy of the Stryd pod was not accurate when implemented for walking, which would be similar for other market marketplace models. The foot device highlights the inconsistency with the theoretical kinetic power method across different devices. Nevertheless, the spatio-temporal measurements are more consistent, and with further research, development and testing within the individual sections an open source standardised method can be produced.
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    Investigating probabilistic techniques for calculating the system capacity in the South African transmission network
    (Stellenbosch : Stellenbosch University, 2024-03) De Bruyn, Johannes; Bekker, Bernard; Dalton, Amaris; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: he large-scale introduction of variable renewable energy (VRE) generators to existing power systems, which were predominantly designed for centralised and dispatchable generation, comes with capacity and stability planning challenges. Academic literature suggests that these challenges are not sufficiently addressed using traditional power system analysis and modelling methods. Many research papers therefore call for the adoption of more statistically sophisticated methodologies that can more adequately describe the uncertainties inherent to variable renewable energy resources. Probabilistic load flow techniques especially have been found to provide a more nuanced representation of the capacity of a power system to host additional generation. This study sets out to prove the hypothesis that using a simplified probabilistic load flow methodology for calculating system capacity would more comprehensively clarify the constraints associated with hosting VRE in the South African transmission network. It does this by developing and applying such a methodology to the Northern Cape transmission network based on similar methodologies in literature. The probabilistic methodology is compared against results gained from a deterministic system capacity analysis also applied to the same portion of the transmission network. Two significant concerns regarding probabilistic analyses are the relatively long solution times and extensive data requirements. Literature suggests that simplifying network representations with equivalent circuits could reduce both while maintaining an acceptable level of accuracy. This study included a brief analysis of these claims by reducing the transmission network model to only the Northern Cape using Ward equivalents for the rest of the system and comparing the power flows in the full and simplified system under various conditions. The results showed that equivalent circuits can reduce solution times considerably without introducing significant errors when care is taken in setting up the internal and external networks. This study further showed that deterministic scenario analyses do not consistently, when seasonal variations are introduced, predict the extreme behaviour of power systems unless a large number of scenarios are considered. Probabilistic system capacity analyses on the other hand were consistent in providing the likely and extreme loading states of the Northern Cape. Recommendations for future studies are the expansion of the methodology presented to include calculating the hosting capacity of the South African system probabilistically to determine whether current deterministic methods are overly conservative in their estimations. Another study would be identifying edge-case scenarios for deterministic analyses in the current South African power system.
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    Development and verification of an electro-mechanical docking mechanism for flight
    (Stellenbosch : Stellenbosch University, 2024-03) Serfontein, Gideon; Jordaan, Willem; Visagie, Lourens; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: This thesis focused on the development of a docking system for CubeSats with the aim of using it in a demonstration mission named DockSat. The system includes a docking adapter and a mechanism to lock the satellites together, a pose estimation system employing both LED fiducial markers and a camera, electromagnetic coils to allow control of relative position and the control algorithms needed. This work, particularly the pose estimation system and docking adapter were based on work done by Robert Waller for his master’s. The different parts of the system were designed with one another in mind. This included the mechanical design that was made to work with the pose estimation system as well as the coil. As a part of this integration, a PCB was designed to act as the back-pane of the docking adapter that could hold the electronics for the electromagnetic coil as well as the LEDs used for the pose estimation. Each part of the system was developed and tested separately. Starting with the docking adapter, the mechanism was updated to make it more robust, manufacturable and lockable. This was tested with a series of tests to test its misalignment robustness and locking force. Secondly, the pose estimation system was integrated into the docking adapter. Tests were conducted to measure its accuracy and it was found to be suitable. Thirdly, magnetic coils were designed to be integrated into the docking adapters. This was done using simplified models of electromagnets as well as simulations. Afterwards the coils’ strength and force were tested. Using the results from previous tests, simulations were done in both 2 and 3 dimensions. PID controllers were designed to control the electromagnets and the reaction wheels. The control scheme was found to be effective to bring the two satellites together from rest to dock. Thus a complete system for docking was formulated. The test results show that the system is suitable for the DockSat mission.
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    The development of a smart monitoring system for solar pv plants by employing AES-encrypted LoRa wireless sensor networks.
    (Stellenbosch : Stellenbosch University, 2024-03) Fourie, Franco; Rix, Arnold J. ; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: Detecting underperforming solar photovoltaic (PV) modules in large-scale installations is challenging, with over 25% of operations and maintenance costs stemming from inefficient maintenance. It is therefore crucial to detect problems within a PV installation as early as possible. This research project has developed an improved wireless monitoring system to enable timely diagnostics and future adaptability, addressing limitations in existing PV monitoring solutions. The implemented system consists of plug-and-play smart field nodes (SFN), a full-duplex gateway, and a web application. A listen before talk communication protocol is implemented to allow for network scalability. Furthermore, a new approach to developing modular, scalable firmware using the active object programming paradigm is introduced. SFNs periodically sample PV panel electrical parameters, temperatures, and battery voltage with a minimum accuracy of 0.68% for voltage, 5% for current, and ±0.5◦C for temperature. The data is encrypted using AES-128 and transmitted to the gateway via LoRa packets. The web application provides an intuitive interface to view real-time and historical SFN data for each PV panel. Field-testing exhibited good measurement accuracy and a 93% packet delivery rate across SFNs. The scalability for over 10 simultaneously communicating SFNs was successfully demonstrated, and further work includes improving the positional accuracy. In summary, the secure smart monitoring system successfully addressed key limitations in existing solutions through enhanced firmware modularity, easier installation, and an accurate universal modular system adaptable for future research. The accuracy and reliability exhibited in preliminary testing validates its potential for use in future solar PV research and development projects.