Faculty of Engineering and Built Environment
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Item The prospect of floating photovoltaic in clean energy provision and net-zero-emissions(Springer Science and Business Media LLC, 2024) Ebhota, Williams S.; Tabakov, Pavel Y.This study emphasizes the critical role of renewable energy in addressing climate change challenges, particularly in reducing greenhouse gas emissions. It highlights the central importance of solar photovoltaic systems. While recognizing South Africa’s progress in renewable energy deployment, the study notes that substantial efforts are still needed to meet the country’s renewable energy targets. The study’s primary aim is to enhance the understanding and deployment of solar photovoltaic systems by critically examining the photovoltaic potential and performance of different sites. To achieve this, two scenarios—land photovoltaic and floating photovoltaic systems—were considered, focusing on hypothetical 10 MWp-installed capacity systems. The results indicate that the 10-MWp land photovoltaic system has a global tilted irradiance of 2184.7 kWh/m2, an annual total output of 18 GWh, and an average yearly performance ratio of 81%. The economic parameters for the land photovoltaic system include a capital expenditure of $9.0 million, an operational expenditure of $157,500 annually, and a levelised cost of energy of $0.04089/kWh. In contrast, the 10-MWp floating photovoltaic system reports a Global Tilted Irradiance of 1797 kWh/m2, an annual total output of 16 GWh, and a performance ratio of 76%. The economic parameters for the floating photovoltaic system include a capital expenditure of $10.6 million, an operational expenditure of $176,250 annually, and a levelised cost of energy of $0.04936/kWh. Both scenarios’ econo-technical parameters fall within acceptable ranges. However, the land photovoltaic system shows better performance, indicating some efficiency loss in the floating photovoltaic system possibly due to harsher offshore conditions. Based on the data from the reports, the study concludes that the econo-technical feasibility of floating photovoltaic in the Western Cape Province of South Africa is high.Item Renewable energy technologies in the global south : Sub-Saharan Africa trends and perspectives(IJETAE Publication House, 2022-01-01) Ebhota, Williams S.; Tabakov, Pavel Y.Sub Saharan Africa (SSA) and other parts of the Global South are richly endowed with renewable energy resources (RERs) that are grossly untapped. The integration of these resources, such as hydro, wind, solar, and biomass will facilitate the desired net zero-CO2-emissions economy. If these RERs are adequately harnessed, the perennial power supply challenges in the region will be resolved, and the negative power supply narrative changed. Presently, a greater percentage of the population without access to electricity live in the Global South with SSA having the highest share. This inadequacy has been attributed to many factors, which include lack of connection to the national grid; lack of adequate technical capacities to design and manufacture efficient power generation and transmission components and systems; insufficient funds; unreliable, limited, and poor energy data. A comprehensive study of the renewable energy potential (REP) and technologies in the Global South is imperative to the management, regulation, and policies concerning energy, in this era of energy transition (ET). This study presents - a summary of REP of SSA; statistical analysis of the proposed and installed RE capacity across the region; and discussion on the pressing need for renewable energy integration (REI) to mitigate climate change. In addition, to develop RE schemes to facilitate greater access to clean, affordable, and adequate energy supply. Actualization of the integration of RERs into the national portfolio will promote CO2 reduction and improve the socio-economic benefits to the populace in both rural and urban areas of SSA and the Global South generally. Keywords— Renewable energy system; Net-zero-CO2 emissions, renewable energy in Global South; hydro; wind; solar; biomassItem A review of the implications of polyethylene plastics when utilized as chemical storage tanks(Journal of Aeronautical Materials, 2024-05-01) Khanyi, Nhlanhla F.; Tabakov, Pavel Y.; Inambao, Freddie L.Many studies have been conducted to investigate the impact or influence of polyethylene (PE) plastic when used as chemical liquid storage. Herein, this literature addresses the factors that contribute to the degradation of chemical storage tanks as a result of PE plastics and how they can be mitigated. This is achieved by reviewing and discussing the significant properties of High-density polyethylene (HDPE), which have been reported to degrade the chemicals stored in these storage tanks. The method of cross-linking the PE was reviewed with its preceding processes that involve chemical and physical processes. The influence of each agent on the resulting properties is discussed in detail including the effect of cross-linking degree. These methods were found to be significant in improving some of the properties of HDPE to better store chemical substances. Nonetheless, it was established that the main concern of PE plastics is environmental stress cracking (ESC), which causes unexpected cracks within the HDPE storage tanks, thus degrading the substance contained. The currently used method or test (bentstrip) to determine the resistance of PE to ESC and techniques used to monitor it were reviewed and discussed in detail. Consequently, the literature suggests that the relationship between the density of PE and its ESC susceptibility has been found to be significant. However, research has shown that relying solely on density as a predictor of ESC in PE when exposed to chemical substances is insufficient, and further studies should be conducted to investigate other parameters that contribute to ESC in PE. In addition, the review suggests that future research should focus on studying ESC resistance of newly developed Nano-filled PE composites or biodegradable PE variants, as these are future materials for storing chemical substances conveniently.Item Biopolymer composite materials in oil and gas sector(Hindawi Limited, 2024-02-21) Abdulrahman, Jibrilla; Ebhota, Williams S.; Tabakov, Pavel Y.In the oil and gas industry, the demand for alternative materials is rising due to corrosion and the desire to reduce costs through weight reduction. Polymer composites are gaining attention for their corrosion resistance, favourable strength-to-weight ratio, and cost-effectiveness. The biopolymer composite is projected to have an output worth $4.95 billion between 2021 and 2025 and growth at a 5.38% compound annual growth rate. This review focuses on exploring the potential of natural fibres as reinforcement for biofibre polymer composite pipes in oil and gas, highlighting their ecofriendliness, biodegradability, and cost-efficiency. The paper assesses biopolymer composite pipes’ development, challenges, and applications, particularly those using continuous basalt and banana fibres. While basalt fibre has found field applications, banana fibre-reinforced polymer composites are still in the early research stages. Despite significant oil and gas industry players already endorsing polymer composites, further research is needed for biopolymer composites to address challenges like compatibility, environmental impact, standardisation, long-term durability, production processes, and regulatory acceptance. Advancing biocomposite research and exploring new research opportunities are essential for engineering advancements and advanced materials.Item Comparative analysis of different computational intelligence techniques for maximum power point tracking of PV systems(University of Oradea, 2022-10-01) Moyo, Ranganai Tawanda; Tabakov, Pavel Y.; Moyo, SibusisoThe performance of a photovoltaic (PV) module can be improved by employing maximum power point tracking (MPPT) controllers. MPPT controllers are algorithms that are included in PV battery charge controllers or inverters to extract the maximum available power from PV modules for any given temperature and irradiance. Several studies report that the use of PV modules without MPPT controllers results in power losses, which ultimately results in the need to install more solar panels for the same power requirement. Numerous techniques of varying complexities have been proposed in the literature to solve the MPPT objective function. This paper presents a comparative analysis of three computational intelligence (CI) based MPPT techniques namely, the fuzzy logic (FL) based controller, artificial neural networks (ANN) based controller, adaptive neuro-fuzzy inference system (ANFIS) based controller and one conventional technique, the perturbation and observation (P&O) controller. These MPPT controllers are designed, simulated and analysed in the MATLAB/Simulink environment. The performance of the studied MPPT techniques is evaluated under steady-state weather conditions, rapidly changing weather conditions and varying load conditions. CI-based MPPT controllers are found to be more efficient than the P&O controller. Moreover, the ANFIS-based MPPT controller shows an outstanding MPPT performance for all the scenarios studied.Item Design and modeling of the ANFIS-based MPPT controller for a solar photovoltaic system(ASME International, 2021-08) Moyo, Ranganai T.; Tabakov, Pavel Y.; Moyo, SibusisoAbstract Maximum power point tracking (MPPT) controllers play an important role in improving the efficiency of solar photovoltaic (SPV) modules. These controllers achieve maximum power transfer from PV modules through impedance matching between the PV modules and the load connected. Several MPPT techniques have been proposed for searching the optimal matching between the PV module and load resistance. These techniques vary in complexity, tracking speed, cost, accuracy, sensor, and hardware requirements. This paper presents the design and modeling of the adaptive neuro-fuzzy inference system (ANFIS)-based MPPT controller. The design consists of a PV module, ANFIS reference model, DC–DC boost converter, and the fuzzy logic (FL) power controller for generating the control signal for the converter. The performance of the proposed ANFIS-based MPPT controller is evaluated through simulations in the matlab/simulink environment. The simulation results demonstrated the effectiveness of the proposed technique since the controller can extract the maximum available power for both steady-state and varying weather conditions. Moreover, a comparative study between the proposed ANFIS-based MPPT controller and the commonly used, perturbation and observation (P&O) MPPT technique is presented. The simulation results reveal that the proposed ANFIS-based MPPT controller is more efficient than the P&O method since it shows a better dynamic response with few oscillations about the maximum power point (MPP). In addition, the proposed FL power controller for generating the duty cycle of the DC–DC boost converter also gave satisfying results for MPPT.Item A comparative analysis of evolutionary algorithms in the design of laminated composite structures(De Gruyter, 2015) Tabakov, Pavel Y.; Moyo, SibusisoAbstract: The increased use of composite materials and structures in many engineering applications led to the need for a more accurate analysis and design optimi-zation. While methods of stress-strain analysis devel-oped faster, optimization techniques have been lagging behind. As a result, many designed structures do not ful-fill their full potential. The present study demonstrates the major achievements in recent years in an application of evolutionary algorithms to the design optimization of fiber-reinforced laminated composite structures. Such structures are of much interest due to high structural design sensitivity to fiber orientations as well as complex multidimensional discrete optimization problems. Using an anisotropic multilayered cylindrical pressure vessel and an exact elasticity solution as an example, we show how the optimum, or near–optimum, solution can be found in a more efficient way.Item Splitting vacancy voids in the grain boundary region by a post-cascade shock wave(Institute of Problems of Mechanical Engineering, 2013) Markidonov, A. V.; Starostenkov, M. D.; Tabakov, Pavel Y.The structural transformation of vacancy voids in the grain boundary region of the bicrystal under the influence of post-cascade shock waves is studied with the aid of molecular dynamics simulations. It is shown that the void may be split into two parts or completely displaced. This effect depends on the relative position of the void and grain boundary dislocations. Also shown is a seamless transfer of vacancy clusters through the tilt grain boundaryItem A computational methodology to select the optimal material combination in laminated composite pressure vessels(2012-12) Tabakov, Pavel Y.; Walker, MarkA methodology to select the best material combination and optimally design laminated composite pres-sure vessels is described. The objective of the optimization is to maximize the critical internal pressure subject to cost constraints. Exact elasticity solutions are obtained using the stress function approach, where the stresses are determined taking into account the closed ends of the cylindrical shell. The approach used here allows us to analyze accurately multilayered pressure vessels with an arbitrary number of orthotropic layers of any thickness and a combination of different materials. The design optimization of the pressure vessel is accomplished using the Big Bang–Big Crunch algorithm,subject to the Tsai-Hill failure criterion.Item Design optimization of anisotropic pressure vessels with manufacturing uncertainties accounted for(Elsevier, 2013-04) Tabakov, Pavel Y.; Walker, MarkAccurate optimal design solutions for most engineering structures present considerable difficulties due to the complexity and multi-modality of the functional design space. The situation is made even more complex when potential manufacturing tolerances must be accounted for in the optimizing process. The present study provides an original in-depth analysis of the problem and then a new technique for determining the optimal design of engineering structures, with manufacturing tolerances accounted for, is proposed and demonstrated. The numerical examples used to demonstrate the technique involve the design optimization of anisotropic fibre-reinforced laminated pressure vessels. It is assumed that the probability of any tolerance value occurring within the tolerance band, compared with any other, is equal, and thus it is a worst-case scenario approach. A genetic algorithm with fitness sharing, including a micro-genetic algorithm, has been found to be very suitable to use, and implemented in the technique.