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A review of the dry methods available for coal beneficiation
Get PDFJournal Article, Faculty of Engineering, Centre of Excellence Carbon Based Fuels-- Potchefstroom CampusWater is a precious global resource that is important in most currently employed coal beneficiation practices. These widely accepted processes deliver consistent and precise separation efficiencies at desired product yields and throughputs. Although favoured, the water usage related to wet processing may be impractical and unsustainable in certain regions. Consequently, present-day practices used in coal processing may soon have to adapt, irrespective of any improved technical and economic feasibility offered. Therefore, the development of efficacious dry beneficiation methods has become an appealing research topic.
This review assembles information pertaining to the principle and success of commercially available and experimental phase dry processes applicable to coal beneficiation. These methods show much potential and, with some consideration of possible limitations and further investigation, may be established in future in the especially arctic, arid, and under-developed regions through new plant installations, expansions, and small mines and fines processing.Acknowledgments and Funding
This study is supported by the Centre of Excellence in Carbon-Based Fuels at North-West University in Potchefstroom, South Africa. Moreover, it receives partial funding from Coaltech and the National Research Foundation (NRF) of South Africa under the Coal Research Chair Grants, with grant numbers: 86880, UID115228, and UID85632. The perspectives, findings, conclusions, or recommendations presented in this research are credited to the authors, and the NRF denies any responsibility for potential associated liabilities
Explainable machine learning model for predictive maintenance in smart agricultural facilities
Get PDF, North-West University, Potchefstroom CampusMachine Learning (ML) models in Smart Agricultural Facilities (SAF) often lack explainability, hindering farmers from taking full advantage of their capabilities. This study tackles this gap by introducing a model that combines a subset of eXplainable Artificial Intelligence (XAI), known as explainable Machine Learning, with Predictive Maintenance (PdM). The model aims to provide both predictive insights and explanations across four key dimensions: (1) data, (2) model, (3) outcome, and (4) end-user. This approach marks a shift in agricultural ML, reshaping how these technologies are understood and applied. The model outperforms related studies, showing quantifiable improvements. Specifically, the Long-Short-Term Memory (LSTM) classifier shows a 5.81% rise in accuracy. The eXtreme Gradient Boosting (XGBoost) classifier exhibits a 7.09% higher F1 score, 10.66% increased accuracy, and a 4.29% increase in Receiver Operating Characteristic-Area Under the Curve (ROC-AUC). These results could lead to more precise maintenance predictions in real-world settings. This study also provides insights into data purity, global and local explanations, and counterfactual scenarios for PdM in SAF. It advances ML by emphasising the importance of explainability beyond traditional accuracy metrics. The results confirm the superiority of the proposed model, marking a significant contribution to PdM in SAF. Moreover, this study promotes the understanding of ML in agriculture, emphasising explainability dimensions. Future research directions are advocated, including multi-modal data integration and implementing Human-in-the-Loop (HITL) systems aimed at improving the effectiveness of ML models and addressing ethical concerns such as Fairness, Accountability, and Transparency (FAT) in agricultural ML applications.Master
Euthanasia as the Right to Life: An African Philosophical Perspective
Get PDFMaster of Philosophy in Philosophy, North-West University, Potchefstroom CampusThis dissertation philosophically investigates the concept of euthanasia and traces the potential impact of legalisation thereof in South Africa. A lacuna in this context is the formulation of euthanasia as a Right to Life from the basis of the Constitution and relating this legal precedent to local African thought. Indeed, euthanasia as a Right to Life has not been a widely explored idea from a Southern African perspective, and its intersection with African thought is explored even less commonly. In this study I draw inspiration from both Western and African sources, since both converge in the South African milieu (the Western approach is particularly relevant in terms of legal frameworks, and the African approach in terms of the broader social context). On the one hand this dissertation explores the idea of euthanasia as a Right to Life from a legal-philosophical perspective, whereby I evaluate and critically analyse South African law and how it may accommodate the legalisation of euthanasia. On the other hand, this dissertation examines African thought in relation to euthanasia to highlight the importance of African concepts such as dignity, quality of life, and personhood, for paving the way for the societal acceptance of euthanasia after possible legalization. By following the intersection of these two lines of thought I investigate our views as a nation with regard to what it means to be a person who can freely make end-of-life decisions in contemporary South Africa. It is highly unusual for a pro-euthansia position to be taken in an African philosophical perspective. A few African thinkers such as Menkiti, Gyeke, and Molefe who have taken up the task of writing on euthanasia, take in a relatively anti-euthanasia perspective. This project therefore aims to set itself apart from other modes of thinking on the subject matter
Analysing the influence of people and culture risk on risk management in the banking sector
Get PDFMaster of Commerce in Risk Management, North-West University, Vanderbijlpark CampusOne of the main determinants for banks to overcome financial and reputational challenges is to manage operational risk to an acceptable level. Banks have been exposed to various operational risks, such as people risk and culture risk. Moreover, this has been exacerbated by employees' lack of positive perceptions about the importance of managing or mitigating people risk and culture risks within the banking sector. Therefore, analysing the influence of people risk and culture risk on risk management in the banking sector is crucial for banks to provide better risk strategies to enhance their employees' perception of operational risk and overall risk management. Operational risks such as people risk and culture risk have impacted other major risks in the banking sector, especially during the COVID-19 pandemic. The COVID-19 pandemic has impacted the banking landscape and changed the usual day-to-day operation of banks by adopting hybrid models that may have impacted culture, how employees used to work, more dependence on banking apps (less contact with people), and increased levels of risk. In South Africa, very few studies focus on people risk and culture risk in the banking sector. Therefore, a gap was found in conducting this research study. The main objective of this research study was to analyse the influence of people risk and culture risk on risk management in the banking sector. The literature review and empirical objectives of the research study were achieved by establishing quantitative research approaches in conjunction with a positivist research paradigm. This research study's target population consisted of South African banking sector employees. The sample frame included the top five South African commercial banks, namely ABSA, FNB, Nedbank, Capitec Bank, and Standard Bank. They were chosen based on market share, number of branches, and profit maximisation. The non-probability purposeful and snowball sampling methods were chosen for this research study as the best methods to gather large amounts of information from limited parameters effectively. Participants who met the inclusion criteria of being 18 years or older with matriculation as a minimum level of education and having more than six months of work experience in the banking sector were obtained as a representative sample. A sample size of 391 employees was considered satisfactory for quantitative data analysis. Quantitative data was collected using a self-administered online questionnaire and validated and pre-tested by seven researchers in the field of risk management. Various statistical analysis tools such as EFA, correlation coefficient, ANOVA, T-test, hypothesis testing, and SEM were used to model the influence of people and culture risk on risk management. The main contributions of the research study are based on the achievement of the empirical objectives and the creation of a model for how people and culture risk (as components of operational risk) influence risk management in the banking sector. For the first empirical objective, a significant difference was found in how individuals perceived risk management and operational risk. The demographic factors (age, ethnicity group, types of employment, and position or role held) were statistically significant, while gender (females) had a greater understanding of operational risk management. For the second empirical objective, it was found that there was a medium-positive linear relationship between operational risk management and risk management perception. Further, operational risk management and risk management perception positively correlated with people risk and culture risk during the COVID-19 pandemic. Lastly, the SEM demonstrated significant results that contributed to achieving the primary objectives. The SEM allows banks to predict factors that influence people risk and culture risk, which are likely to be the most valuable intangible assets of the bank. Consequently, this will help banks develop mitigation strategies and action plans to manage these operational risks. Managing any operational risk will allow banks to strive for more profit, competitive advantage, a better working environment, a strong reputation, an enabling culture, a better perception of risk, and ensure that risk is within acceptable risk appetite levels. Considering this research study's theoretical and empirical findings, limitations will always be part of any research study, as they are used to improve the current study. Future researchers can use this research study as a basis to improve the study by choosing a larger sample size and expanding the range of demographic factors. As this research study focused on people risk and culture risk as part of operational risk, future researchers may consider other types of risk such as reputational risk, market risk, credit risk, financial risk, information communication and technology risk and strategic risk with a focus on the banking sector.-North-West Universit
Development of a deep neural network framework for sailplane cross-country performance optimisation
Get PDFDoctor of Philosophy in Engineering with Computer and
Electronic Engineering, North-West University, Potchefstroom CampusTraditional sailplane cross-country performance optimisation is a slow and computationally expensive task as it requires the integration of multiple simulation packages and function evaluations for each span-wise station and flight condition. Traditional methods also prohibit expert input to this optimisation process. Deep neural networks, with their powerful generalisation capability, provide a possible solution for replacing the computationally expensive simulation packages with lower fidelity surrogate models, ultimately reducing the time spent on the preliminary sailplane design and optimisation phase. In this research, a deep learning framework for sailplane cross-country performance optimisation is developed to address these shortcomings of the traditional model. Various modelling techniques are employed to build a deep learning based system that is accurate, computationally efficient, and which enables expert input upfront to the optimisation process. For the expert input, deep learning modules are developed, enabling airfoil generation from parsimonious shape and structural variables. Constraining this parsimonious variable search space, therefore, enables intuitive constraint settings on the wing and individual airfoil designs. It is shown that the deep learning framework not only outperforms the traditional model in terms of computational efficiency but is also able to find wing/airfoil combinations that outperform defined baseline designs whilst adhering to all constraints imposed on the final design. Specifically, the efficacy and validity of the proposed deep learning framework is shown where it is applied to realise a 0.9% average increase in the cross-country performance of the JS4 sailplane – a State-Of-The- Art (SOTA) standard class sailplane and currently one of the worlds best performing models. This deep learning framework therefore facilitates rapid, accurate, and targeted wing/airfoil design explorations and ultimately reduces the time spent on design, especially in the preliminary design phases, and has been shown to possess the capability of cross-country performance optimisation of SOTA standard class sailplane designs.Doctor of Philosoph
Effects of river regulation on aquatic invertebrate community composition: A comparative analysis in two southern African rivers
Get PDFJournal Article, Faculty of Natural and Agricultural Sciences, Unit for Environmental Sciences and Management-- Potchefstroom CampusWhile natural floods play a crucial role in shaping the composition of aquatic communities, the most rivers worldwide are regulated or dammed for anthropogenic purposes, resulting in alterations to the biological and chemical composition of these ecosystems. Studies have demonstrated various negative effects of river regulation on aquatic invertebrate communities globally. However, there is a scarcity of research in Africa, despite its vulnerability to anthropogenic impacts. This study aimed to compare aquatic invertebrate communities in the Phongolo River, an impacted regulated river, and the Usuthu River, a less impacted unregulated river, in South Africa. It further aimed to ascertain whether Lake Nyamithi, a naturally saline lake receiving water from both of the aforementioned systems, exhibited a stronger similarity to one of the two rivers in terms of its aquatic invertebrate composition. Aquatic invertebrate and water samples were collected from 2012 to 2018 over several surveys. The Usuthu River demonstrated a diverse and sensitive aquatic invertebrate community, emphasising its high conservation value. The Phongolo River demonstrated effects of anthropogenic impact, with taxa more resilient to changes in water quality and flow compared to the Usuthu River. Mismanagement and excessive water use may lead to the loss of any remaining sensitive aquatic invertebrate communities in this river. The presence of invasive molluscan in the Phongolo River and Lake Nyamithi also poses a threat to the native aquatic invertebrate communities. These invasive species are currently absent from the Usuthu River although other invasive species, such as the Australian redclaw crayfish, are found in both river systems. Lake Nyamithi displayed a unique aquatic invertebrate community, distinct from both rivers and their floodplains. This study provides important baseline information on the Usuthu River's aquatic invertebrates and emphasises the need to maintain adequate water flow in rivers and floodplains to protect biodiversity and sensitive speciesNational Research Foundation, Grant/ Award Number: 105122, 115415 and 127549; Deutscher Akademischer Austauschdiens
Exploring variability of drought events for the western region of South Africa
Get PDF, North-West University, Mahikeng CampusThe occurrence of drought in South Africa is inevitable, as it is a naturally occurring phenomenon. What makes this phenomenon extreme is its creeping nature, which could unravel into prolonged, socio-economic drought. Socio-economic drought imposes the greatest threat to agriculture and the economy. Examples of this type of drought recently (at the time of this study) occurred in the Northern Cape, Western Cape, North West, Free State, and Eastern Cape provinces. Most of these provinces were declared disaster regions because of prolonged drought and/or underwent socio-economic impacts. Parts of these provinces are located in the western region of South Africa, which is the area of interest in this study due to its dry nature. The standardised precipitation evapotranspiration index (SPEI) was used to analyse the potential changes in the drought frequency, duration, and intensity of district municipalities. Those findings were linked to potential changes in vegetation, by examining the normalized
difference vegetation index (NDVI) trends. The SPEI was then used to examine future drought events from 2050-2100 using Coupled Model Intercomparison Project (CMIP6) data, which was compared to the data from 1962-2022. The 1962-2022 findings showed that the frequency,
duration, and intensity of drought had worsened in all district municipalities in the second half of the study period. During the extensive drought period of 2012-2022, a decrease in the NDVI values is present. Yet, the NDVI trends showed an overall increase in all five provinces, meaning that the worsened drought conditions, observed in the SPEI, did not reflect on the NDVI to the same degree. Only 4/17 district municipalities are predicted to have worsened drought conditions in 2050-2100 in comparison to the 1962-2022 results. Overall, this study provides insight into the intensities, frequencies, and duration of past and future drought events in the district municipalities. This information can enable stakeholders, policymakers, mayors, etc. of the district municipalities to proactively prepare for worsening drought conditions.-Climatology Research Group (CRG)Master
A comparative literature study of the place of worship in pastoral counseling in a multi-cultural church facing conflict
Get PDFMaster of Theology in Pastoral Studies, North-West University, Potchefstroom CampusThis study intends to recommend guidelines on how a multicultural congregation can address worship-related challenges brought about by diversity. Also, to identify strategies that can be adopted to mitigate worship challenges. For example, a church can be multiracial yet culturally homogenous because members of the same cultural group hold all power and influence in the congregation. The study’s objective is to evaluate unique challenges and potential of how worship can enrich believers' lives when worshipping in Spirit and truth in the mission context. Presenting critical aspects in worship in a multicultural congregation means presenting an inter-cultural engagement that models critical multiculturalism and focuses on relationship building and survival, which embodies learning from one another through empathy, interactions, and respect. Therefore, the study proposes worship as a possible guideline for the unique challenges in a multicultural congregation. The study reviews literature on conflicts associated with multicultural congregations in order to understand the construct and possible solutions. Furthermore, it assesses grammatical-historical exegesis of relevant passages from the Bible concerned with worship in Spirit and truth. This diversity of methods enabled the researcher to understand the theme: the conflict between believers from different cultures and the relation of this problem to the correct worship practices. Such an understanding define the contribution of worship to tolerance and peace among members. The model of practical theology designed by Osmer (2008:4) was used to guide the study. This model identifies four tasks of practical-theological research, descriptive, interpretative, normative, and pragmatic tasks. The four tasks aim to assess the problem and its possible solution. Osmer's primary objective is for leaders to be efficient, interpretive guides to teach congregants (Osmer, 2008:22). As such, this study aimed to suggest a model that church leaders may consider in addressing intercultural conflict.-North-West Universit
Fish predation affects invertebrate community structure of tropical temporary ponds, with downstream effects on phytoplankton that are obscured by pesticide pollution☆
Get PDFJournal Article, Faculty of Natural and Agricultural Sciences, Unit for Environmental Sciences and Management-- Potchefstroom CampusAquatic biota of tropical temporary ponds typically experience a wide range of stressors that can drive the structure and dynamics of natural communities. Particularly in regions with intense agricultural activity, aquatic biota may not only experience predation pressure but also stress from pesticides that inadvertently enter the ponds. We increasingly understand how these different sources of stress affect classic model taxa under controlled laboratory conditions, but how predators and pesticides may jointly affect pond invertebrate communities is still unclear, particularly for tropical systems. Here, we conducted an outdoor mesocosm experiment to study how fish predation combined with exposure to an environmentally relevant concentration of the commonly used insecticide cypermethrin (0.8 ng/L) affects the structure of invertebrate communities, and its potential effects on leaf litter decomposition and invertebrate grazing efficiency as measures of ecosystem functioning. A total of seven invertebrate taxa were recorded in the mesocosm communities. Fish predation effectively lowered the number of invertebrate taxa, with fish mesocosms being dominated by high densities of rotifers, associated with lower phytoplankton levels, but only when communities were not simultaneously exposed to cypermethrin. In contrast, cypermethrin exposure did not affect invertebrate community structure, and neither fish predation nor cypermethrin exposure affected our measures of ecosystem functioning. These findings suggest that predation by killifish can strongly affect invertebrate community structure of tropical temporary ponds, and that downstream effects on phytoplankton biomass can be mediated by exposure to cypermethrin. More broadly, we contend that a deeper understanding of (tropical) temporary pond ecology is necessary to effectively manage these increasingly polluted systems.Acknowledgments
-This work was funded by Flemish Inter-university Council for University Development Cooperation (VLIR-UOS), Belgium (Grant number ZIUS2013AP029), through an institutional cooperation programme (IUC) with the Nelson Mandela African Institution of Science and Technology (NM-AIST), under the research project ‘Applied Aquatic Ecology: Sustaining healthy aquatic ecosystems in Northern Tanzania to promote long term sustainable ecosystem services that improve the livelihoods of local communities’. We thank the Tanzania wildlife Research Institute for assisting in permit processing (TWRI/RS-331/VOL.IV/2013/39). We are also grateful to laboratory staff at the Magugu TPRI station for offering assistance, space, and utilities needed for setting up full-scale mesocosm experiment
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