Browse
Recent Submissions
Item Combining bio-based cementation with cement stabilisation for road construction(2024-07) Smit, Michelle A; Rust, FCThe growing concerns over climate change and the move towards sustainable, costeffective road development have resulted in the development of bio-based construction methods. Microbial induced calcium carbonate precipitation (MICP) binds material through the formation of calcite bridges between soil grains. Current MICP treatment techniques, however, are not compatible with road construction processes. Due to this the Council for Scientific and Industrial Research (CSIR) has started investigating bio-stabiliser treatment techniques for road construction. The objective of this paper is to present Unconfinded compressive strength (UCS) results for a G8 material stabilised using in-situ bacteria present in the soil. After 10 days of cementation solution treatments a UCS dry result of 1.16MPa was achieved. No wet UCS results were, however, produced as all the samples disintegrated. The decision was made to supplement MICP with 0.7% cement. Not only did UCS wet results show a 100% increase compared with MICP only treated samples, but the UCS dry results were comparable to adding 2.5% cement to the G8 material. Partial replacement of cement with MICP during stabilisation could lead to an overall reduction in the amount of cement used in road construction without compromising strength, which will have a positive environmental and economic impact.Item Towards greener networks: Evaluating power consumption in popular open RAN environments(2024) Ebrahim, Rozeena; Vilakazi, Mlamuli C; Burger, Chris R; Lysko, Albert AEnergy efficiency, power consumption, and their cost and environmental impacts have become critical considerations in telecommunications, including fifth-generation (5G) and beyond mobile networks. This work investigates power consumption within open Radio Access Network (RAN) implementations for 4G and 5G mobile networks, such as OpenAirInterface (OAI) and Software Radio Systems RAN (srsRAN). Using two measurement tools, a hardware measurement setup and the software tool Turbostat, we evaluate and compare the power consumption across various RAN environments on our inhouse mobile network testbeds. We also compare the power consumption profiles for each RAN environment under different modes/tasks. From this comparison of considered versions, we found that the srsRAN platform consumes less power than the OAI RAN for both 4G and 5G setups potentially resulting in lower operational costs in open RAN deployments.Item Solving the privacy and security challenge using ZKP: Its positive impact on the economy(2024-12) Ntshangase, Cynthia S; Baruni, Kedimotse P; Myaka, Zanele S; Mahlasela, Oyena NThe 4th and 5th industrial revolutions are improving the functioning of the working environment for different industries. However, it also introduces security and privacy challenges that lead to cybercrime which negatively impacts the economy. This article presents a comprehensive analysis of the usage of Zero Knowledge Proofs (ZKP) to protect data in the major technologies for the 4th and 5th industrial revolutions. These technologies include cloud computing, big data, Internet of Things, blockchain, 5G, artificial intelligence, and supply chain. Security and privacy challenges and solutions in these technologies were investigated. ZKP, a cryptographic method that enables verification of a party without revealing confidential details, is one of the promising solutions to fight the problem of data security and privacy. In this study, it was determined that Blockchain is the leading technology in terms of using the ZKP to improve security and enhance privacy. The paper provides the future direction to secure these technologies using cryptographic methods such as ZKP.Item Tales from three construction sites: A qualitative investigation into work zone safety(2024-07) Mokgatle, K; Nemauluma, L; Miyambu, M; Van Gruting, WA; Juba, A; Masombuka, B; Lowe, J; Sampson, J; Menon, A; Ben-Edigbe, J; De Beer, E; Venter, KarienRoads form the backbone of the South African economy, and the provision of adequate road infrastructure is key to facilitate socio-economic change. Many of South Africa’s roads are facing increasing growth in traffic volumes, congestion, and the infrastructure is aging. Construction works are needed to add capacity as well as to maintain existing infrastructure. The construction work has an impact on the safety of the travelling public as well as on workers on site, who are exposed to traffic constantly. Typically, roadwork zones are welldefined areas, but they are dynamic, and roadworks contracts necessitate constant change, which impacts on the segments under construction, making safe operation an ongoing effort. This paper explores work zone safety by making use of qualitative observations from three existing work zones on the national road network. The sites were largely rural, and safety concerns related to traffic accommodation were identified. The use of signage to safely redirect traffic, safety considerations in terms of personnel and equipment on site as well as public driving behaviour are key elements in ensuring safe work zone areas. In line with the Safe System Approach, the process of designing and building safer roads and roadsides needs to be managed to minimise risk to both road workers and the travelling public.Item Integrating commercial Off-The-Shelf (COTS) technologies to enhance military capabilities(2024-07) Thaba, James M; Mtsweni, JabuThe landscape of warfare is constantly evolving, demanding innovative approaches to maintain a technological edge. Integrating Commercial Off-The-Shelf (COTS) technologies offers a promising avenue for militaries to enhance capabilities while optimizing resources. Although this integration offers opportunities, there is no standardised approach available to militaries to ensure successful integration. This paper explores Capability Engineering (CE) as an approach suitable to successfully integrate COTS technologies in military operations. The paper explores literature for CE and related applications, including the literature related to the integration of COTS in military systems. The paper then presents the rationale for CE framework for the implementation of COTS integration in military capabilities. The contribution of this research is the proposal of the Capability Engineering (CE) framework for integrating COTS products at various levels of Military Capabilities (MC). The paper also presents some examples of COTS products integration in military capabilities.Item Mobility management in 5G heterogeneous networks: A scheme for reducing handover failures(2024-12) Monaheng, R; Ramotsoela, D; Lysko, Albert AMobile/cellular communication has become very popular in recent decades and has evolved considerably. Cellular communications are shifting towards heterogeneous inter-connectivity. Ultra-dense heterogeneous networks (HetNets) employing small cells (SCs) within a macro cell's coverage area represent a highly promising strategy for boosting both capacity and coverage in 5G cellular networks. An ultra-dense network (UDN) refers to a setup where the number of Radio Access Technologies (RATs) present in a specific geographic location is increased. An ultra-dense network (UDN) is a setup in which the number of Radio Access Technologies (RATs) in a given geographic area is enhanced. As a result, the areas covered by each RAT start to overlap. Small base stations (SBSs) are situated close together in a UDN. Consequently, a single user equipment (UE) might pick up signals from multiple SBS, leading to significant inter-cell interference. This scenario typically arises due to a delayed handover. In environments with densely packed small cells, inter-cell interference is prevalent, causing deterioration in signal quality and subpar service for users. In this respect, we deal with mobility management from the point of view of users' mobility support in multi-RAT and multi-layer environments. We aim to reduce handover failures due to the unavailability of resources at the target base station (BS)/cell/RAT. We implemented a handover strategy that lowers the number of dropped handover calls by using a semi-Markov mobility prediction algorithm for handover control. This allows for the reservation of resources in the destination base station ahead of time, considerably reducing the amount of handover failures. The suggested scheme's findings were validated using a MATLAB simulation of an environment containing tiny cells with various radio access methods. According to the simulation results, predicting the next position of the user equipment resulted in lesser handover call dropping as opposed to new call blocking because they were not expected and thus resources were not prepared for them.Item Analysis of Ceilometer LiDAR (CL51) sensor atmospheric profile images for urban environmental monitoring over Pretoria, South Africa(2024-12) Faniso-Mnyaka, Zimbini; Magidimisha, Edwin; Dikole, Realeboga G; Sekopa, Teboho LClouds are a critical component of the atmosphere, influencing both climate and weather patterns, while their backscatter impacts human activities and lives. The CL 51 Ceilometer LiDAR is one of the advanced atmospheric sensors deployed globally to collect massive data for monitoring environmental conditions. This sensor captures data in digital format, which is subsequently converted into images. However, extracting atmospheric features, such as aerosol distribution along the sensor's path length, requires precise identification for effective analysis. In this paper, we outline the methodology for data acquisition, conversion to image format, and feature extraction of atmospheric components from the CL 51 script. We further analyse the atmospheric images derived from CL 51 seasonal data collected in Pretoria from 2014 to 2015. This analysis of CL 51 ceilometer LiDAR images will enhance our knowledge and understanding of the atmospheric aerosol profile, thereby contributing to urban environmental monitoring efforts.Item 3D Physical model study for the Haifa breakwater retrofit design(2024-05) Wehlitz, Carl-Peter FV; Somlota, Lukhanyo LSince the original designs were performed without current wave forecasting data that accounted for climate change and sea level rise, the Port of Haifa is becoming more frequently subjected to extreme storm events. These storms have caused major damage to the port’s main breakwater, and the rock used in the 1930 vintage portion of the structure has deteriorated. A 3D physical model study was commissioned with the objective to assess and verify the stability of a retrofit design proposed to enhance the structural integrity of the main breakwater. The design included major modifications to the structure, with the most prominent being a new armour layer. This would result in the widening of the breakwater, as well as raising the crest. Results from this study showed that a single-layer Cubipod armour layer would be sufficient to cope with the extreme conditions tested. A variation to the design was, however, required at two sections of the breakwater where World War II vintage historic fire command towers are located. This is because design restrictions prohibited any alterations to these towers and the adjacent crest areas. The variations included a milder seaward slope, as well as constructing a double-layer armour layer at these locations.Item Enhancing safe mobility using inclusive intelligent infrastructure management system(2024-07) Abejide, Samuel O; Adedeji, JAIn the dynamic realm of urbanization, smart city development, particularly in relation to transportation infrastructure, is gaining momentum. This study addresses a gap in the current strategies by emphasizing effective management over mere expansion. Managing infrastructure systems is essential given the increasing trend of tech-driven transportation and the vehicle-to-capacity ratio. To maximize the current infrastructure in East London, South Africa, the Inclusive Intelligent Infrastructure Management System (IIIMS) is the suggested solution. For more sophisticated transportation system design, the project combines data-driven approaches with intelligent transportation systems (ITS). Demand management, predictive maintenance, route optimization, and real-time data collection are important components of this approach. By offering information on traffic patterns, hotspots for congestion, and possible conflicts, these initiatives support well-informed decision-making for capacity expansion. Focusing on Oxford Street, a congested area in East London, this research employs the smart city wheel and the 15-minute smart city concept. The IIIMS loop incorporates adaptive hypotheses for safe mobility principles in a specific spatial and temporal context. By examining the elements of an inclusive intelligent transportation system, this study considers telematic technologies, data-driven traffic management, and safe mobility principles. Hypotheses related to private vehicle access, worker safety, citizen well-being, and urbanized infrastructure management are discussed, offering solutions for safe mobility. The proposed framework includes an operational level-of-service (LOS) lane change modification for Oxford Street, promoting flow and reducing congestion. Recommendations should focus on competitive measures for delay-time management, congestion patterns, and hotspot identification, contributing to smart city discourse and emphasizing inclusive intelligent infrastructure management for safe mobility and urban transportation competitiveness.Item Occurrence and potential hazard of pharmaceutically active compounds in coastal waters in Cape Town(2024) Newman, Brent K; Velayudan, Anisha; Oelofse, Gregg; Colenbrander, Darryl; Petrović, Mira; Álvarez-Muñoz, Diana; Čelić, Mira; Le Roux, Maria; Ndungu, Kria; Madikizela, Lawrence M; Chimuka, Luke; Richards, HeidiThis presentation provides details on investigations into the prevalence, concentrations, and potential ecological impacts of pharmaceutically active compounds in coastal waters in Cape Town.Item Assessing the risks of cyberthreats associated with military-specific information management systems(2024-11) Chauke, Mapoo D; Mphadzha, Fhumulani R; Nwanebu, Docas DThe Fourth Industrial Revolution introduced rapid changes to technology, societal patterns and processes through increased interconnectivity, smart automation and access of data. Cybersecurity threats are inevitable in the 4th Industrial era and thus, protection against these threats is essential. Cybersecurity involves protecting computer systems, communication networks, and digital applications, along with the data they hold, from unauthorized access and attacks. These attacks, also known as cyberattacks, are aimed at fraudulently accessing concealed information for malicious damage such as changing, stealing or destroying information. Cyberthreats are an inherent risk to any system, whether it’s internet or intranet based. The growing complexity and volatility of the global security environment have led to military organizations developing decision support systems to support and aid operational effectiveness. The capability management decision support system is a military system developed to assist planners and decision makers in assessing their capability status and for deployment planning. The system is mission critical and may be exposed to cyberthreats such as spywares, malwares, ransomware and Distributed Denial of Service. Military systems are susceptible to cyber security threats and effective cyber protection must be put in place when using these systems. The system is in its final stages of development and is ready for deployment. In planning for deployment of the system, an analysis of vulnerabilities and threats that the system might encounter is essential. This paper gives a theoretical analysis of cyber threats the system might be vulnerable to and recommends actions to protect the system.Item Feasibility of South African natural zeolites for low temperature thermal energy storage(2024-11) Sheik, Muhammad; Segakweng, Tshiamo; Van Reenen, Tobias HSolar thermal systems can support a substantial heat demand in the industrial and residential sectors, but it does not always match demand. Therefore, thermal energy storage (TES) is critical in these systems. Among the different TES methods, adsorption and absorption (sorption) heat storage is promising compared to conventional sensible TES and latent TES. Sorption based thermochemical heat storage offers high energy densities as well as exceptional advantages in minimizing losses when utilised for long-term heat storage solutions. Furthermore, sorption systems can be regenerated at relatively low temperatures (approximately 120 °C) which are achievable by solar collectors. To commercialize sorption storage systems, additional research and development is required to make them more economical. One of the most promising material types for TES is Zeolites which can store approximately 150 kWhth/m3. Typical applications for zeolite include drying, space heating and carbon capture. Natural zeolite is available locally in South Africa at a tenth of the price of the commercial grade zeolite 13X. However, natural zeolites may contain structures and impurities which can negatively affect the adsorption capacity. It is therefore necessary to investigate the TES properties for any relevant source. A lab-scale prototype was developed to analyse the thermal storage characteristics of natural (clinoptilolite sourced from a local supplier) in an open (non-pressurised) sorption system. The experiments that were conducted involved a reversible reaction between a solid (natural zeolite) and a gas (water vapour in air). The findings from the study will be evaluated to determine the feasibility of locally sourced natural zeolite for thermal energy storage.Item Multi-temporal assessment of woody canopy cover changes in South Africa; products and analysis based on GEDI, sentinel-1 and 2 data(2024-07) Qabaqaba, M; Naidoo, L; Tsele, P; Ramoelo, A; Cho, Moses AMonitoring of forest extent and structure at national scale is essential task in the context of climate change for conserving biodiversity, developing national forestry inventories and projecting the future of terrestrial carbon sinks. Multitemporal monitoring of woody canopy cover is needed to achieve the aforementioned task. The current study sought to demonstrate the potential of remote sensing sensors in generating multi-temporal woody canopy cover products for South Africa. The combination of freely available high spatial and temporal resolution from sentinel-2 (multispectral) and sentinel-1 (Synthetic Aperture Radar) and with canopy cover samples from the Global Ecosystems Dynamics Investigation (GEDI) enables multi-temporal assessment of woody canopy cover. The use of Random Forest (RF) machine learning algorithm to model woody structure over a period of five years (2019 – 2023) revealed changes in some woody biomes of South Africa, due to fragmentation, bush encroachment and degradation. These products provide national information on woody canopy cover on a consistent basis. Furthermore, the products provide a better understanding on the changes, distribution and extent of woody ecosystems in South Africa.Item Climate change impacts on South Africa’s estuaries, estuarine associated fish species and potential for mitigation and adaptation(2024-10) James, Nicola; Van Niekerk, Lara; Lamberth, Stephen; Potts, Warren; Edworthy, Carla; Whitfield, Alan; Deyze, ShaunThe presentation details the climate change impacts on South Africa’s estuaries, estuarine associated fish species and potential for mitigation and adaptation.Item Fairness and One Health in Food Systems: Developing the Research Agenda(2024-11) Zata, M; Grobbelaar, SS; Meyer, Isabella AThis article explores the extant literature on Fairness and One Health within Food Systems. This was conducted using the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses - Scoping Review) methodology. The approach identifies the themes relevant to Fairness and One Health and how they interact. Bibliometric analysis was conducted using Bibliometrix (available in R-package software) and Visioviewer to identify appropriate and consistent key trends of Fairness, One Health, and the interconnectedness of the two concepts. These are then used to propose key future research directions. The research agenda focuses on several key themes within Fairness, One Health, intersection, and emerging areas. Under Fairness themes, it explores enhancing Food Justice for equitable access, the impact of Social Justice policies on food distribution in marginalised communities, and the effects of Environmental Justice on food production and security.Item Technology roadmapping for defence: A systematic literature review and research gaps(2024-07) Malinga, Andries L; Letaba, P; Pretorius, MWThis research explores the existing literature on technology roadmapping (TRM) in the Defence context. A systematic literature review was conducted to identify studies from Scopus, Web of Science, and IEEExplore, and qualitative thematic analysis was used to analyse the relevant studies. Five emerged from the literature: tools development, process and framework customisation, process customisation, framework customisation, and integration. In addition, the study also highlight the need for skill training, collaboration, and inclusive participation in the Defence roadmapping process. The research contributes to the literature reviews on technology roadmapping by identifying studies tailored to the nuances of the Defence context.Item Green ammonia production: Comparing batteries and H2 Gas Turbines for plant operation continuity(2024-07) Roos, Thomas H; Coetzee, Rigardt A; Uhorakeye, T; Pambhar, DGlobal ammonia production is a hard-to-abate sector, because: 1) feedstock H2 production is fossil-based (natural gas reforming or coal gasification), and 2) fossil-based grid power is used to drive both the air separation unit (ASU) for feedstock N2 and feedstock gas compression upstream of the Haber-Bosch (HB) synthesis unit. By contrast, green ammonia (GNH3) production decarbonises both the feedstock (green H2 from electrolysis with renewable electricity or RE) and the power for compression and ASU (also RE). This 2nd requirement adds a complication: HB synthesis plants do not 1.5 NH3 production cost (USD/kg) 1.4 1.3 1.2 1.1 1 70% SF 80% SF 90% SF 60% SF 30% SF 50% SF 20% SF 40% SF 10% SF 2 1.5 1 1.5 NH3 production cost (USD/kg) 3 2.5 1.4 1.3 1.2 1.1 1 70% SF 80% SF 90% SF 60% SF 30% SF 50% SF 20% SF 40% SF 10% SF 2 1.5 1 3 2.5 RE/Electrolyser capacity ratio RE/Electrolyser capacity ratio 70 60 50 80% SF 90% SF 60% SF 50% SF 20% SF 30% SF 70 70% SF 40% SF 10% SF 60 50 80% SF 90% SF 60% SF 50% SF 70% SF 40% SF 10% SF 20% SF 30% SF 40 40 tolerate power cycling due to RE intermittency. The exothermic NH3 synthesis reaction requires the feedstock gases to pass over a catalyst bed at elevated pressure and temperature. The heat of reaction released is transferred by heat exchanger to the incoming feedstock gases. An insufficient supply of either feedstock gas or RE power results in the flowrate decreasing, reaching the point where the reaction is no longer self-sustaining (determined by Cheema et al to be 33% of rated capacity [1]), and the HB plant shuts down. Under such circumstances there is a risk is that the catalyst cools down. Repeated thermal cycling results in catalyst degradation, necessitating a shutdown to replace the catalyst.Item Physical model tests on stability and overtopping of new concrete armour unit Cubilok(2024-04) Cairns, M; Holtzhausen, Anton; Wehlitz, Carl-Peter FVThe Cubilok™ is a new concrete armour unit developed by PRDW Consulting Ports and Coastal Engineers, with the flexibility to modify its shape and structural robustness. This study was the first attempt to understand the modified unit’s hydraulic stability and recommended wave overtopping rate. The primary objective of this research was to investigate the behaviour of the Cubilok at slopes of 1:1.5 and 1:1.33 (V:H), which involved testing various wave heights and periods. The unit’s viability as a single and double layer was investigated in this study. The research comprised of multiple 2D physical model setups and was conducted at the CSIR in Stellenbosch, South Africa. The results indicated that the Cubilok performed well on steeper slopes, showing potential competitiveness with other single-layer units. Additionally, the results indicated that the overtopping rate increased significantly for low wave steepness values. Further investigations are suggested to address variability in test results.Item Legal and ethical considerations in IoT forensic investigations: A study on global perspective(2024-11) Nelufule, Nthatheni; Shadung, Lesiba D; Senamela, Pertunia M; Manari, Unarine JSeveral technological industries have been revolutionized by the advent of Industry 4.0 technologies, but more sophisticated cyber threats have become a challenge for digital forensic investigations. This is caused by the large volumes of sensitive data that are generated and shared across these technologies, which presents ethical and legal questions. Notwithstanding these difficulties, digital evidence has its uses. This article compares similar moral and legal dilemmas across the globe with an emphasis on forensic investigators' approaches to overcoming these challenges. The difficulties forensic investigators encounter in overcoming these difficulties are also covered in the essay.Item Design approach for the access channel of Port Victoria, Seychelles(2024-04) Terblanche, L; Rossouw, M; Troch, Christophe NAExisting spatial and infrastructural limitations of Port Victoria and its potential effect on Seychelles' economy have made the expansion of the port essential for future development. To accommodate postPanamax container vessels and fuel tankers with static drafts of up to 14 m, the port basin and access channel must be expanded and deepened. The design approach for the new access channel comprised: an assessment of the existing vertical and horizontal channel dimensions; a conceptual design, based on empirical channel design guidelines; and a detailed probabilistic assessment using ship motion and navigation simulation models. Fast-time navigation simulations were conducted and supplemented with real-time simulations. The navigation simulation data were statistically analysed to confirm the alignment and horizontal dimensions of the access channel. The vertical dimensions of the channel were determined by a vertical response analysis of the design vessel to ensure sufficient under-keel clearance while transiting the channel. The use of modelling and simulation proved to be valuable in refining the dimensions necessary for the safe navigation and manoeuvring of the proposed design vessels. These dimensions informed the dredging requirements for the project.