DSpace Repository

Welcome to the NWU Repository, the open access Institutional Repository of the North-West University (NWU-IR). This is a digital archive that collects, preserves and distributes research material created by members of NWU. The aim of the NWU-IR is to increase the visibility, availability and impact of the research output of the North-West University through Open Access, search engine indexing and harvesting by several initiatives.

Now showing 1 - 17 of 17

Recent Submissions

Characterising ambient air quality over Gauteng using surface in-situ and remotely derived measurements
(North-West University, 2024) Sibisi, Zamahlase
Air quality studies using ground-based and satellite retrievals have gained popularity over the past two decades, offering many techniques and methods to explain atmospheric observations and contribute to climate predictions. Satellite retrievals assist us in capturing what ground-based measurements cannot; however, this is not to infer that one can be successfully employed as a proxy for the other. Ground-based measurements have presented major limitations on spatial coverage and data quality. This study aims to comprehensively assess air quality in the Gauteng Province, focusing on urban and industrial communities, by combining ground-based and remotely derived measurements. The first objective was to characterise ambient PM2.5 levels in the Gauteng region using ground-based measurements by identifying and analysing temporal trends, diurnal variations, and seasonal fluctuations in ground-based PM2.5 measurements. Secondary data for pollutant concentrations and meteorological data was used. The second objective is to evaluate the accuracy of satellite-derived data over the Gauteng region by validating the Aerosol Optical Depth (AOD) observations for MODISTERRA and MODISAQUA using the ground-based Aerosol Robotic Network (AERONET) observations. This objective used three retrieval algorithms, namely “Deep Blue (DB)”, “Dark Target (DT)”, and “Combined Deep Blue and Dark Target (DB & DT)”, to facilitate satellite AOD validations. The last objective was to characterise the aerosol loadings over Gauteng using satellite observations and modelled reanalysis data by comparing observations of AOD from MODISTERRA, MODISAQUA, and the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) as well as characterising the aerosol type using the Ångström Exponent (α) for the monitored and unmonitored regions in Gauteng. ArcMap v10.8.1 was used for raster analysis and visualisation. The results show that PM2.5 concentrations are still localised in low-income communities where major sources of pollution are biomass and waste burning, and domestic fuel burning, and industrial activities. When validating AOD, the “Combined DB & DB” algorithm performed best with the Machine Learning (ML) – SciKit-Learn model with a 90% model performance as opposed to the SLR and OLS statistical models. The retrieval algorithm performed better with satellite data from MODISAQUA. MERRA-2 was the most efficient in capturing aerosol species distribution. The findings highlight the importance of satellite validation studies as meteorological and topographic features impact different geographic areas. The findings suggest exploring different atmospheric measurement and monitoring techniques to fully understand the limitations in air quality studies and finding measures fully capture the PM2.5 spatial distribution and AOD coverage.
Exploring the challenges and opportunities for the management of shared watercourses: The case of the Orange - Senqu River Commission
(North-West University, 2024) Sibanda, Lungelo; Moolman, H.J; Malherbe, C.W
The term “shared watercourses”, also referred to as transboundary watercourses, refers to watercourses that extend across multiple countries. As noted by Petersen-Pelman et al. (2017), approximately 60% of the world’s freshwater resources are situated in these shared watercourses. Consequently, the responsible management of these shared watercourses is imperative to maintain their well-being, ensure benefits for all member states, and prevent conflicts among them. Numerous countries sharing water resources have endeavoured to establish legal frameworks for the governance of these watercourses. The primary instruments for managing shared watercourses on a global scale are the 1997 UN International Watercourses Convention and the Helsinki rules (1966). Within the Southern African Development Community (SADC) Region, the Protocol for Shared Watercourses in the SADC region serves as a key tool for managing such resources. This protocol has led to the creation of various water commissions, including the Limpopo River Commission (LIMCOM), Zambezi River Commission (ZAMCOM), and Orange Senqu River Commission (ORASECOM). The research explores the challenges and opportunities for the management of shared watercourses within the Orange Senqu River Commission (ORASECOM). The study followed a qualitative research methodology with semi-structured interviews as the instrument for soliciting data. Purposive sampling was implemented to determine the research participants who were the ORASECOM task team members. The challenges for implementing the ORASECOM Agreement range from legal and regulatory challenges, political and diplomatic challenges, technical and infrastructural challenges, environmental and legal challenges, economic and financial challenges, capacity building challenges and monitoring and evaluation challenges. The research went on to explore the opportunities or potential benefits that can be reaped out of successful implementation of the ORASECOM Agreement. The research findings and literature revealed the strategies on how to overcome the challenges for implementation of the ORASECOM Agreement. These strategies include numerous dimensions, beginning with the critical role of financial and economic approaches. Securing international funding, diversifying funding sources, and mobilizing resources emerge as pivotal strategies to ensure the agreement’s financial sustainability. Capacity building and institutional strengthening, both in terms of technical proficiency and community engagement, are underscored as essential components. Recommendations and future research areas were suggested based on the research findings. Recommendations include improving on community participation and involvement, securing financial resources for the implementation of the ORASECOM Agreement as well as learning from successful environmental management reforms practices in other shared watercourses. Moreover diplomacy, well-organized action plans, adaptability, and consistent communication, harmonizing the laws can be used to increase solidarity in shared water resources management. Use of financial tools and investments necessary for infrastructure development making educational and training investments in task team members, increased research, delineation of aquifers, monitoring evaluation of ground water, as well as data sharing among member states regarding ground water information should be considered. These recommendations also form a basis for future research areas.
Exploring opportunities for implementing waste-to-energy projects in the City of Johannesburg Metropolitan Municipality
(2024) Radingoana, Nakgwe Donald; Van Niekerk, CS; Kruger, L
This study explores opportunities for implementing waste-to-energy technologies to alleviate the City of Johannesburg’s (CoJ) current waste management challenges as well as the current energy crisis in the country. Globally, untreated, unsafe disposal, and inefficient waste collection have contributed to a waste crisis, while a rapidly increasing world population has increased waste generation, and a higher demand for energy. Waste-to-energy is therefore increasingly viewed as a viable solution to waste management and energy supply challenges. However, South Africa underutilises waste for energy generation. CoJ has initiated the adoption of waste-to-energy projects for electricity, but little progress has been made on the actual implementation. This study therefore investigates the potential for implementing waste-to-energy projects in the CoJ to recommend strategies for successfully enhancing both waste management and energy generation in the city. A qualitative approach was used to conduct the study and semistructured interviews were utilised for collecting primary data. Using purposive sampling, 20 managers and employees in CoJ’s waste management and energy departments were selected. The study found that implementing waste-to-energy projects offers numerous benefits to CoJ, including freeing up landfill space, improving energy supply, and contributing to environmental sustainability. Additionally, the study found that the successful implementation of waste-to-energy projects is complex and hinges on a number of factors, including the availability of human, financial, and technological resources, a supportive regulatory and policy environment, and the participation of all stakeholders. Recommendations include the development of employee skills and competencies and the mobilisation of financial resources through increased focus on public-private partnerships. Management is also encouraged to collaborate with policymakers to revise legislation, regulations, and policies that govern waste management and renewable energy and replace it with supportive legislation and policies. Lastly, management should promote a culture of separation at the source and increase the level of public participation.
Characterising the urinary acylcarnitine and amino acid profiles of patients with HIV/TB co-infection, using LC-MS metabolomics
(North-West University, 2024) Pretorius, Charles; Luies, L
This study comprises a comprehensive investigation of the urinary acylcarnitine and amino acid profiles in patients with HIV, TB, and HIV/TB co-infection using LC-MS metabolomics. It addresses a critical gap in current research by exploring the metabolic interplay in HIV/TB co-infection, a domain less extensively studied compared to the individual effects of HIV and Mtb infection. Recognising the potential of metabolomics in enhancing our understanding of HIV/TB co-infection and its immunological impact on host metabolism, this research aimed to characterise the urinary metabolome of individuals afflicted by these conditions. Such insights are pivotal for developing novel treatments and diagnostic strategies to effectively manage the HIV/TB syndemic. In this pursuit, urine samples from 9 HIV/TB co-infected, 7 HIV-only, and 41 TB-only patients, along with 32 healthy controls, were analysed. The analysis employed three targeted HPLC-MS/MS methods, allowing for the distinct assessment of urinary amino acids using the ChromSystems MassChrom® Amino Acid Analysis kit, as well as acylcarnitines and the tryptophan derivative 5-hydroxyindoleacetic acid (5-HIAA) through newly established and validated methods. The validation of these methods encompassed a thorough evaluation of selectivity, linearity, precision, and accuracy, ensuring the reliability of the findings. The results revealed significant alterations in the amino acid metabolome across all infected cohorts. Notably, there was a marked decrease in tryptophan and glycine levels, coupled with increased saccharopine and hydroxykynurenine levels. Enhanced lysine degradation via the saccharopine pathway was evident in HIV/TB co-infected and TB-only patients, as indicated by a significantly increased saccharopine/lysine ratio. While amino acid levels predominantly decreased in the HIV-only patients, an increase was observed in those with TB-only compared to healthy controls. The co-infected cohort did not exhibit a clear trend, suggesting a complex interplay of metabolic processes in the co-infection state. Although changes in acylcarnitines and 5-HIAA were not statistically significant, there were indications of generally elevated medium-chain acylcarnitines in the TB-only and HIV/TB co-infected cohorts. These findings point towards an altered net protein turnover, inflammation, lipid and amino acid catabolism, and potentially diabetic-like hyperglycaemia in the HIV/TB co-infected state, predominantly driven by Mtb infection. Furthermore, this study lays the groundwork for future research aiming to identify robust disease markers, as it suggests that the effects of HIV and Mtb infection on the amino acid metabolome are attenuated in the co-infected state. Overall, this study not only contributes to a deeper understanding of the metabolic complexities associated with HIV, TB, and their co-infection but also opens new avenues for targeted therapeutic interventions in managing these challenging infectious diseases.
Simplified Temporal Convolutional-based Channel Estimation for a WiFi Vehicular Communication Channel
(IEEE, 2025) Ngorima, Simbarashe Aldrin; Helberg, Albert; Davel, Marelie H.
Channel estimation in vehicular communication is a crucial element in the advancement of intelligent transportation systems. However, the use of pilot signals in the IEEE 802.11p standard is insufficient for accurate channel estimation in high mobility scenarios. Data pilot-aided (DPA) estimation helps address this, but suffers from demapping errors. We propose a simplified Temporal Convolutional Network-based estimator (DPA-TCN) trained on a mixed signal-to-noise ratio dataset to improve estimation performance and reduce computational complexity. Our DPA-TCN estimator achieves a bit error rate comparable to a state-of-the-art long-short-term memory network with DPA and temporal averaging (LSTM-DPA-TA) while reducing the complexity of the model by approximately 65%. Index Terms—channel estimation, deep learning, IEEE 802.11p, TCN, vehicle-to-vehicle, wireless communications.A