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Item 5.9 - Modelling estuaries in data-poor environments(Elsevier, 2024-03) Scharler, UM; Gerber, G; Taljaard, Susan; Mackay, FModels are inherently data-hungry for the construction, calibration, validation and predictive capacity that is demanded of models. In data-poor environments, a severe challenge to modelling is the lack of historic data, and present lack of sufficient monitoring programmes of important variables and number of estuarine ecosystems. This is largely due to lack of infrastructure, skills, political will, and monetary support. However, environmental challenges do not wait for adequate datasets to arrive to inform decision-making, and therefore different pathways to modelling that inform both research and management are needed. We present approaches to water quality, ecosystem modelling and climate change research in South African estuaries, as a representative of a data-poor environment. Such approaches aim to use available data in novel ways to inform research and decision-making, and identify data and information gaps. We propose that such methods be used in other data-poor areas with similar types of estuaries as South Africa and we provide recommendations how to construct, validate and use models and their outcomes. The communication of model uncertainty for research purposes and to decision-makers takes an important place in such endeavours.Item Development of a new asphalt mix design manual for South Africa(2015-08) Anochie-Boateng, J; O’Connell, JS; Verhaeghe, BMJ; Myburgh, PA need existed to update the South African design methods for asphalt mixes, particularly in the light of current developments in the country such as the revision of the South African Road Design System (SARDS), and the increasing demand for, and the use of products such as high modulus asphalt mixes with reclaimed asphalt and slags, warm mix, and cold mix as alternative mixes to conventional hot-mix asphalt. Generally, there is a worldwide shift from empirical-based asphalt mix design approach towards performance-related design approaches, due to advances in asphalt technology, increased volumes of heavy vehicles on roads, and there is also a demand for higher performance mixes, and a need to review the current criteria for asphalt layers in contract specifications. This paper presents the development of a new asphalt design manual. The paper presents key highlights such as (a) the performance grade binder selection methodology in which the binder is selected based on loading and environmental conditions, as a replacement of the traditional penetration grade binder selection method, (b) the move from aggregate grading bands (as per the current South African Committee of Transport Officials specifications) towards the use of control points to select the design aggregate grading, and (c) the three levels of asphalt mix designs proposed for the manual. The manual however, requires validation through additional laboratory testing before it can be used with confidence by industry.Item Scenarios for the South African maritime sector(CSIR, 2014-11) Claassen, M; Funke, NS; Lysko, MD; Ntombela, CP; Funke, NS; Claassen, M; Meissner, R; Nortje, KThe chapter explores possible scenarios for the South African maritime sector through the application of established scenarios theory.Item Performance of geopolymer concrete subjected to mineral acid tests in static and dynamic conditions(52-69, 2024-01) Dlamini, Mandla N; Alexander, M; De Jager, PetaGeopolymer cements are an emerging alternative binder to Portland cements, characterised by an alumino-silicate polymer network nanostructure. These binders are purported to possess numerous beneficial properties such as acid resistance and a relatively low carbon footprint. This study sought to assess the performance of a fly ash-based geopolymer concrete developed at the CSIR, exposed to mineral acids (HCl and H2SO4) under static and dynamic exposure conditions. Portland cement and calcium aluminate cement concretes using calcareous aggregates (dolomite) were used as control specimens, while geopolymer cements were mixed with a range of calcareous and siliceous aggregates. The test results show that the resistance of geopolymer concretes exposed to hydrochloric acid in dynamic and static conditions is significantly higher than Portland cement and calcium aluminate cement concretes, where mass loss was used as a measure. The study also shows that the acid resistance of geopolymers can be further improved by combining them with siliceous aggregates instead of calcareous aggregates. Furthermore, a linear empirical relationship, between basicity (related to the major acidic and basic oxides established via XRF) and the rate of dissolution of concrete in acidic solutions was observed. Basicity was also related to preferential corrosion in concrete mixtures exposed to the dynamic HCl test, and it was found that the difference in the basicity of the paste and aggregate of concrete mixture was useful in determining the type and extent of preferential corrosion.Item SADC’s settlement hierarchy and networks in support of cross-border regional development(Routledge, 2024-03) Maritz, Johan; Le Roux, Alize; Van Huyssteen, ElsonaThis chapter emphasises the merit of creating a SADC regional settlement profile. It unfolds in three segments: review of regional settlement development trends; spotlight on urban significance and the imperative of a shared settlement profile, with South African typologies as a case study; and an analytical outline leveraging collective datasets to dissect SADC's evolving settlement terrain.Item Ground-based surveillance and classification radar for wildlife protection(2023-11) Berndt, Robert J; Wabeke, Leon O; Van Rensburg, Vanessa; Potgieter, Pieter F; Kloke, Kevin HWildlife poaching has become an increasingly large problem over the last decade in southern Africa. There have consequently been worrying declines in rhinoceros population levels. As part of a multi-year effort to investigate and develop technology to aid in the prevention of poaching activities, a C-band phased array radar, with integrated ground target classification capability, has been produced. In a field trial that took place in the Kruger National Park Game Reserve in South Africa, it successfully detected and classified human and animal movement at ranges of up to 10 km. The misclassification rate of humans was less than 7%, and non-human movement, predominantly from animals and vehicles, was incorrectly classified as human 3.8% of the time. This shows that modern radar, without assistance from other sensors, has great potential to contribute towards the preservation of scarce wildlife resources.Item Potential opportunities to convert waste to bio-based chemicals at an industrial scale in South Africa(2023-10) Mandree, PM; Thopil, GA; Ramchuran, Santosh OGlobally, greater than 30% of waste is disposed of in some form of landfill, and it is estimated that annual waste-related emissions will increase by up to 76% by 2050. Emissions arising from fossil fuel-derived products and waste disposal in landfills have prompted the development of alternative technologies that utilize renewable resources. Biomass feedstock is being investigated globally to produce renewable fuels and chemicals. Globally, crop-based biomass and waste biomass are the major feedstocks for chemical production, and the market value of crop-based biomass is expected to increase at the fastest rate. South America, Europe, and North America are currently the global leaders in renewable or bio-based chemical production. In South Africa (SA), the country is still heavily reliant on landfilling as a waste solution. Wastes from agricultural production processes in SA are considered promising feedstocks for beneficiation opportunities to produce bio-based chemicals. The second-generation (2G) agricultural feedstocks that can be used in SA include fruit waste; sugarcane by-products and waste; forestry, timber, pulp, and paper waste; and invasive alien plants. Fermentation, or “green chemistry” technologies, can be used to convert various feedstocks into bio-based chemicals. Bio-based chemicals may be used as drop-in substitutes for existing petrochemical products, for use in end-user industries such as automotive and transportation, textiles, pharmaceuticals, consumer and home appliances, healthcare, and food and beverages. Bioethanol, specifically, can be used in transport fuel, as feedstock for power generation, as an energy source for fuel cells along with hydrogen, and as feedstock in the chemicals industry. Bio-butanol, an olefin derivative, can be used as a drop-in replacement for petroleum-based butanol in all its applications. Different monomers of bio-based chemicals can be used to produce biopolymers, polyhydroxyalkanoates (PHAs), and polylactic acid (PLA), which are subsequently used to produce bioplastics. A total of 25 bio-based chemicals and the technology used to produce them are summarized in this paper. Overall, bioethanol remains the dominant sugar platform product globally. Drawing on global trends, the potential options for the South African market include bioethanol, n-butanol, acetic acid, and lactic acid. It is estimated that the conversion of 70% of the lignocellulosic biomass available in SA would meet 24% of the country’s liquid fuel requirement as a bioethanol equivalent. The most feasible sources of lignocellulosic biomass or waste for beneficiation in SA are generated by the agricultural sector, including sugarcane by-products and waste. Taking into consideration the abundance of lignocellulosic biomass, adequate market segment sizes, and socio-economic factors, it is apparent that there are potential opportunities to investigate the co-production of bioethanol with lactic acid or other bio-based chemicals on an industrial scale.Item Uncertainty in disaster risk management: A reflection on cyclone idai using the systems thinking approach(Springer, 2021-07) Mutanga, Shingirirai S; Lunga, W; Mutanga, Shingirirai S; Nhamo, G; Dube, KThe increasing frequency of disasters induced by anthropogenic and natural hazards has epitomised the complex nature of dealing with uncertainty. Cyclone Idai-induced floods in Southern Africa had a series of foreseeable and unforeseeable risks that affected vulnerable communities in Malawi, Mozambique and Zimbabwe. Thus a key question to address is what systems and mechanisms can vulnerable countries to disasters apply to effectively respond and mitigate challenges posed by disasters. The effects of Cyclone Idai during and after the disaster across the human and physical spheres of society as alluded to in this chapter highlight the need for suitable tools that can assist in unpacking the complexity of disaster management challenges. Adopting a mixed method approach, this chapter proposes systems thinking as a tool that can be applied in disaster risk reduction, taking into consideration that communities constitute intersected and intra- and interdependent subsystems. This chapter advances the need for disaster risk reduction which goes beyond linear approaches of risk management to non-linear frameworks. Essentially, the chapter applies complex systems thinking to enrich existing approaches by recognising known/knowable and unknown risks as well as the interconnectivity between policy, institutions and the society.Item Integrated framework for enhancing SDN security and reliability(2023-11) Isong, B; Ratanang, T; Gasela, N; Abu-Mahfouz, Adnan MIThis paper addresses the issues of fault tolerance (FT) and intrusion detection (ID) in the Software-defined networking (SDN) environment. We design an integrated model that combines the FT-Manager as an FT mechanism and an ID-Manager, as an ID technique to collaboratively detect and mitigate threats in the SDN. The ID-Manager employs a machine learning (ML) technique to identify anomalous traffic accurately and effectively. Both techniques in the integrated model leverage the controllerswitches communication for real-time network statistics collection. While the full implementation of the framework is yet to be realized, experimental evaluations have been conducted to identify the most suitable ML algorithm for ID-Manager to classify network traffic using a benchmarking dataset and various performance metrics. The principal component analysis method was utilized for feature engineering optimization, and the results indicate that the Random Forest (RF) classifier outperforms other algorithms with 99.9% accuracy, precision, and recall. Based on these findings, the paper recommended RF as the ideal choice for ID design in the integrated model. We also stress the significance and potential benefits of the integrated model to sustain SDN network security and dependability.Item Understanding diarrhoeal diseases in response to climate variability and drought in Cape Town, South Africa: A mixed methods approach(2023-08) Lee, TT; Dalvie, MA; Röösli, MS; Merten, S; Kwiatkowski, M; Sweijd, Neville A; Cissé, G; Mahomed, HBackground: The climate of southern Africa is expected to become hotter and drier with more frequent severe droughts and the incidence of diarrhoea to increase. From 2015 to 2018, Cape Town, South Africa, experienced a severe drought which resulted in extreme water conservation efforts. We aimed to gain a more holistic understanding of the relationship between diarrhoea in young children and climate variability in a system stressed by water scarcity. Methods: Using a mixed-methods approach, we explored diarrhoeal disease incidence in children under 5 years between 2010 to 2019 in Cape Town, primarily in the public health system through routinely collected diarrhoeal incidence and weather station data. We developed a negative binomial regression model to understand the relationship between temperature, precipitation, and relative humidity on incidence of diarrhoea with dehydration. We conducted in-depth interviews with stakeholders in the fields of health, environment, and human development on perceptions around diarrhoea and health-related interventions both prior to and over the drought, and analysed them through the framework method. Results: From diarrhoeal incidence data, the diarrhoea with dehydration incidence decreased over the decade studied, e.g. reduction of 64.7% in 2019 [95% confidence interval (CI): 5.5–7.2%] compared to 2010, with no increase during the severe drought period. Over the hot dry diarrhoeal season (November to May), the monthly diarrhoea with dehydration incidence increased by 7.4% (95% CI: 4.5–10.3%) per 1 °C increase in temperature and 2.6% (95% CI: 1.7–3.5%) per 1% increase in relative humidity in the unlagged model. Stakeholder interviews found that extensive and sustained diarrhoeal interventions were perceived to be responsible for the overall reduction in diarrhoeal incidence and mortality over the prior decade. During the drought, as diarrhoeal interventions were maintained, the expected increase in incidence in the public health sector did not occur. Conclusions: We found that that diarrhoeal incidence has decreased over the last decade and that incidence is strongly influenced by local temperature and humidity, particularly over the hot dry season. While climate change and extreme weather events especially stress systems supporting vulnerable populations such as young children, maintaining strong and consistent public health interventions helps to reduce negative health impacts.Item Machine learning – Imaging applications in transport systems: A review(2023-11) Adams, A; Abu-Mahfouz, Adnan MI; Hancke, GPTransport systems are fundamental to supporting economic growth, and the need for smarter, safer, more efficient and climate neutral transport systems continues to grow. Maintenance and operation of transport infrastructure is expensive and has many difficulties. In recent years, the application of machine learning to solve problems has been pursued with varying success rates. Many open problems still remain at this stage. This paper provides a review of deep learning applications in transport systems. Multiple deep learning applications are discussed e.g. railway safety, self-driving cars, pedestrian crossing and traffic light detection. Reviewed papers are evaluated in terms of challenges, contribution, weakness, research gaps. Key research questions for future study are proposed: performance optimization, data set improvement and the need for research on real-time performance on edge devices.Item Towards a privacy compliance assessment toolkit(2023-06) Moabalobelo, Phindile T; Ngobeni, Sipho J; Molema, Bokang C; Pantsi, Phumeza N; Dlamini, Thandokuhle M; Nelufule, NthatheniThe South African Protection of Personal Information (POPI) Act No.4 of 2013 makes it illegal to collect, use, process or store personal information unless it is done in accordance with the prescribed legal and regulatory clauses enriched in the Act. Organizations should take stock of the personal information they collect and who they share it with before they can put controls in place to safeguard it. Failure to comply with POPI Act may potentially expose the responsible party and its associated third parties to steep legal penalties including possibly imprisonment of up to 10 years or R10 million fine which is imposed by the Information Regulator of South Africa. This paper presents the results of a system called Protection of Personal Information Act Compliance Assessment Toolkit (PCAT). The main aim of this system is to assist organisations to assess their current state of compliance to the POPI Act. The PCAT solution followed an experimental research and development process, where three existing similar technologies in the market were analysed and compared to the PCAT. The results of the PCAT shows that it simplifies the POPIA compliance requirements compared to the other three existing technologies. Future work will include development of executive summary report which will make it easier for executive to view the compliance assessment in a high-level format.Item Defining the South African acute respiratory infectious disease season(2023-01) Motlogeloa, O; Fitchett, JM; Sweijd, Neville AThe acute respiratory infectious disease season, or colloquially the “flu season”, is defined as the annually recurring period characterized by the prevalence of an outbreak of acute respiratory infectious diseases. It has been widely agreed that this season spans the winter period globally, but the precise timing or intensity of the season onset in South Africa is not well defined. This limits the efficacy of the public health sector to vaccinate for influenza timeously and for health facilities to synchronize efficiently for an increase in cases. This study explores the statistical intensity thresholds in defining this season to determine the start and finish date of the acute respiratory infectious disease season in South Africa. Two sets of data were utilized: public-sector hospitalization data that included laboratory-tested RSV and influenza cases and private-sector medical insurance claims under ICD 10 codes J111, J118, J110, and J00. Using the intensity threshold methodology proposed by the US CDC in 2017, various thresholds were tested for alignment with the nineteen-week flu season as proposed by the South African NICD. This resulted in varying thresholds for each province. The respiratory disease season commences in May and ends in September. These findings were seen in hospitalization cases and medical insurance claim cases, particularly with influenza-positive cases in Baragwanath hospital for the year 2019. These statistically determined intensity thresholds and timing of the acute respiratory infectious disease season allow for improved surveillance and preparedness among the public and private healthcare.Item In living colour – South African aquatic scientists make a splash in biodiversity campaign(2024-01) Lain, Elisabeth J; Smith, Marie EA new age of satellite remote sensing is upon us. High-tech sensors capable of imaging the earth at over 100 spectral wavebands are now a reality. These sensors, known as hyperspectral radiometers, capture very fine spectral features of the colours emitted from the surface of the earth and its water bodies, offering opportunities for improved satellite-based environmental monitoring. South African researchers are primed and ready to make use of these new technologies to derive water quality parameters from hyperspectral radiometric measurements by applying it towards monitoring our diverse estuaries, dams and oceans. So writes Lisl Lain and Marie Smith of CSIR.Item Efficacy of a plant-produced clade 2.3.4.4 H5 influenza virus-like particle vaccine in layer hens(2022-06) Abolnik, C; O'Kennedy, Martha M; Murphy, MA; Wandrag, DBROutbreaks caused by Goose/Guangdong H5 highly pathogenic avian influenza (HPAI)-lineage viruses continue to occur in unprecedented numbers throughout Eurasia, the Middle East and Africa, causing billions of dollars in economic losses and the deaths or destruction of hundreds of millions of poultry, and pose a zoonotic threat. Here, a recombinant virus-like particle (VLP) displaying the hemagglutinin protein of a clade 2.3.4.4b H5N8 HPAI strain was produced in tobacco plants (Nicotiana benthamiana) and its immunogenicity with four commercial adjuvants was compared in layer hens. After two immunizations with 250 hemagglutinating unit doses, hens that received intramuscular injections of H5 VLPs formulated with Emulsigen D, Emulsigen P or Montanide ISA 71VG seroconverted with hemagglutination inhibition geometric mean titres (GMTs) of 7.3 log2 (± 1.17), 8 log2 (± 1.08) and 7.9 log2 (±1.07), respectively, but the GMT of hens inoculated by eye drop with VLPs plus Carbigen only reached 2.05 log2 (± 1.64). The H5 VLP plus Emulsigen-P vaccinated hens and a sham-vaccinated group were then challenged with a high dose of the homologous H5N8 HPAI virus. Vaccinated hens were completely protected and showed no clinical signs, whereas the sham-vaccinated birds all died within 3–4 days. The average oropharyngeal shedding in vaccinated hens was reduced by 3,487-fold and 472-fold on days 2 and 3 post challenge, respectively, whereas average cloacal shedding was reduced by 2,360,098-fold and 15,608-fold on days 2 and 3, respectively, compared to the sham-vaccinated controls. No virus was detected in the vaccinated hens after day 8 post challenge, and the plant-produced H5 VLP vaccine completely prevented H5N8 HPAI virus transmission to eggs. This highly efficacious, safe and non-toxic plant-produced H5 VLP vaccine with DIVA (differentiation of infected from vaccinated animals) capability could be rapidly produced with a yield of at least 85,000 doses per Kg of plant leaf material.Item Environmental challenges to meeting sustainable development goals in Southern Africa(Springer, 2024-01) Mutanga, Shingirirai S; Skhosana, Felix; Mateyisi, Mohau; Thenga, Humbelani F; Naidoo, Sasha; Ramoelo, A; Nangombe, Shingirai S; Lumsden, Trevor G; Von Maltitz, GP; Midgley, GF; Veitch, J; Brümmer, C; Rötte, RP; Viehberg, FA; Veste, MThere is an inextricable link between ecosystem integrity and the potential for achieving sustainable development goals (SDG). This chapter highlights key ecosystem threats and their drivers within the southern African regional context to emphasize the role of earth system science in supporting the achievement of regional sustainable development goals. It describes how some major anthropogenic threats have unfolded in terrestrial, aquatic and marine ecosystems of the region. Earth system science is increasingly contributing to understanding how globally driven climate and environmental changes threaten these ecosystems, and in turn how these impact people’s livelihoods. Long-term changes in rainfall variability, concomitant disruption of hydrological balances, impacts on ocean chemistry, together with more immediate impacts on the frequency and magnitude of extreme climate events are some of the critical global change drivers. While terrestrial ecosystems are already faced with encroachment by novel species, characterized by the proliferation of both invasive alien and endemic woody species, freshwater and marine ecosystems appear more immediately threatened by more local impacts, such as the accumulation of contaminants. Overall, predicted climate and environmental changes are projected to hamper development trajectories and poverty reduction efforts, and possibly exacerbate adverse impacts on human livelihoods.Item Cradle-to-gate environmental life cycle assessment of limestone calcined clay cement (LC3)(Alive2Green, 2024-01) Dumani, Nozonke; Mapiravana, Joseph; De Jager, PetaThe manufacturing of cement contributes to approximately 5-7% of global anthropogenic carbon dioxide emissions, necessitating the need for reducing the environmental impact. Limestone Calcined Clay Cement (LC3) has emerged as a promising alternative to ordinary Portland cement (OPC), leveraging widely available resources like clay, limestone and gypsum to partially replace the carbon intensive Portland clinker. One ton of Portland cement is associated with about one (1) ton of CO2 . This study aimed to assess and compare the CO2 emissions of theoretical binary and LC3 cement types against 100% Ordinary Portland Cement (OPC). Considered were: OPC with 30% calcined clay replacement, and LC3, composed of 50% clinker, 30% calcined clay, 15% limestone, and 5% gypsum.Item Quantifying the environmental impacts of a sustainable concrete mix for a block paving system(Cape Town: Alive2Green, 2024-01) Dumani, Nozonke; Mokoena, Refiloe; Mgangira, MartinA sustainable concrete mix design, incorporating industrial by-products: fly ash and recycled plastic pellets, was developed, and optimized through laboratory performance-based testing trials. The primary objective of this investigation was to offer environmentally sustainable alternatives to conventional concrete mixes that can be used for concrete block paving and aligns with circular economy principles and fosters enhanced employment opportunities and poverty reduction. Following a laboratory investigation to optimise the quantities of fly ash and plastic pellets in the concrete mix, paving blocks were produced in the laboratory using the optimised mix. The blocks were also tested to ensure compliance with performance criteria stipulated in national specifications for concrete block paving. This chapter focusses on the comprehensive life cycle assessment (LCA) conducted to investigate the environmental impacts associated with the production of the optimised concrete mix design in comparison with two references mixes. All three mixes comprised varying quantities of cement, fly ash as a partial cement replacement, and plastic pellets as a partial substitute for sand. The analysis included concrete with 100% Portland limestone cement, concrete with 50% Portland limestone cement and 50% fly ash, and concrete with 50% Portland limestone cement, 50% fly ash, and plastic pellets. The study, limited to a cradle-to-gate analysis, utilized the life cycle assessment software tool SimaPro 8.1 with the Ecoinvent Database version 3. The life cycle inventory dataset for each material was compiled, and the CML-IA Baseline World 2000 method was employed to generate and report the results. The LCA study results demonstrated that adding fly ash as a cement substitution significantly reduced the environmental impacts of concrete mixes. However, the extent of this reduction depended on the type of allocation method used. Under no allocation and economic allocation scenarios, concrete mixes with fly ash exhibited lower environmental impacts than those without fly ash. Conversely, mass allocation scenarios indicated higher environmental impacts for concrete with added fly ash more than 35%. Additionally, it was noted that environmental impacts for fly ash concrete mixes with plastic pellets as a partial substitute for sand were marginally higher than those with fly ash concrete mixes using only sand.Item Recommendations for sustainable post COVID-19 eLearning development in rural schools in South Africa(2023-12) Mthethwa, Siyabonga; Nthatheni, Ronewa G; Maremi, Keneilwe J; Thulare, TumisoPrior to the COVID-19 pandemic, many ICT initiatives were implemented in rural schools across the country to improve teaching and learning. This paper discusses the various factors that contributed to the failure to sustain ICT initiatives. Due to the risk of infection associated with face-to-face contact during the COVID-19 Pandemic, eLearning proved to be the sole means of ensuring educational continuity. The objective of this paper is to highlight factors affecting sustainability and provide recommendations that can assist in ensuring sustainable ICT initiatives in rural schools after the COVID-19 pandemic. This is accomplished by conducting a scoping review to investigate the sustainability of ICT infrastructure to enable eLearning. The following academic databases are used for scoping literature reviews: ScienceDirect, IEEE Xplore, and search engines such as Google. A total of 41 papers out of 800 publications were deemed appropriate for the analysis. The findings show that physical, management, social, and educational conditions all have an impact on the sustainability of ICT initiatives; thus, addressing these components can ensure sustainability.Item The circular economy, human settlements and municipal government(Alive2Green, 2024-01) Cooper, Antony K; Kruger, Tinus; Godfrey, Linda K; Napier, Mark; De Jager, PetaThe linear economy is where resources (including energy and space) move through the economy in one direction, from being harvested, collected or mined, through refining and processing to create products and services, to uses and consumption, until being discarded. This creates value only while available resources are entering at one end and the waste exiting at the other does not foul up anything, or even everything.This chapter considers the current resources within human settlements for circularity, the expected trends, the potential resource constraints for future growth of circularity, key economic and socio-economic gains and losses associated with the linear economy, and opportunities for the circular economy in human settlements.