Conference Publications

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10-year statistical study of double stratopause structure as observed by lidar over a southern sub-tropical site, Reunion Island (21°S, 55°E)
(2006-07) Sivakumar, V; Faduilhe, D; Bencherif, H
The lidar data collected for about 10 year’s period from 1994 to 2004 are used for the present study. The recorded raw data is in the form of photon count profiles with a height resolution of 300 m and time resolution of 120s. The method of deriving the temperature profile from the measured photon count profile closely follows the method adopted by Hauchecorne and Chanin [1980]
1st review of the status of national air quality: 1994-2004
(2006-10) Taviv, I; Zunckel, M; Mahema, T; John, Juanette; Naidoo, Mogesh
Need for informed decision making, history of fragmented and un-coordinated monitoring, framework for NAQIS-SAAQIS (output of NAQMPII) and metadata collection (output of NAQMPII).
2 DOF resolution adjustment laser position sensor
(Massey University, 2008-12) Shaik, A; Tlale, NS; Bright, G
A low cost sensor system is envisaged that has 2 distinct routes for resolution enhancement in position detection. The main area for application of the sensor design would be in the food processing and packaging industry where position resolution of the end effector is in the millimeter to submillimeter range. The sensor concept consists of a grid of laser light detectors attached to the stationary base and a grid of lasers attached to the mobile end effector. The photo detectors on the base provide one level for position detection enhancement, i.e. the density of the sensor array. The second degree of freedom in improvement comes from the strategic positioning of a set of lasers attached to the end effector.
The 2011 municipal elections in South Africa and new trends since the 2009 national elections
(Operations Society of South Africa, 2011-09) Greben, JM; Elphinstone, CD; Holloway, Jennifer P
The CSIR has been involved in South African election night predictions since 1999 using a cluster prediction model based on the segmentation of the electorate according to voting behavior. In this paper these clusters are exploited in another way. Different clusters are related to different demographic groups, and an analysis is made how these different groups change their affiliation between subsequent elections. The changes in affiliation are determined by calculating a trend matrix, a new tool in elections that was introduced by one of the authors a few years ago. By comparing trend matrices between municipal (2006, 2011) and national elections (2004 and 2009) one can establish whether the observed trends are incidental or have a more generic character. It is felt that a better understanding of the voter behavior through such analyses can enhance the value of elections and thereby promote democracy.
The 2020 WMO symposium on climatological, meteorological and environmental factors in the COVID-19 pandemic: A special issue from symposium presentations
(2021-06) Sweijd, Neville; Zaitchik, BF
The COVID-19 pandemic has become one of the great historical events of the modern era, presenting a generational challenge to the world. Questions about the role of weather on SARS-CoV-2 transmission led to the gathering of scientists at an online event, the “International Virtual Symposium on Climatological, Meteorological and Environmental factors in the COVID-19 pandemic,” convened on 4–6 August 2020 under the auspices of the World Meteorological Organization. This collection of papers arise from the Symposium.
25m2 target-aligned heliostat with closed-loop control
(2007-09) Roos, TH; Zwane, NX; Kruger, E; Perumal, S; Cathro, R
A 252m target-aligned research heliostat with closed-loop control, with a theoretical concentration of 80 suns, has been built at CSIR in South Africa. The heliostat has four degrees of freedom: Azimuth, Elevation, Rotation and Pitch. A control system making use of a solar tracker has been developed and tested on a 1.252m target-aligned miniheliostat. A tracking accuracy of 3.3 milliradians was obtained. A good focal spot has been obtained with the 252m target-aligned research heliostat.
2D Methods for pose invariant face recognition
(IEEE, 2016-12) Mokoena, Ntabiseng; Djonon Tsague, Hippolyte; Helberg, A
The ability to recognise face images under random pose is a task that is done effortlessly by human beings. However, for a computer system, recognising face images under varying poses still remains an open research area. Face recognition across pose is the ability of a face recognition technology (FRT) to recognise face images in different viewpoints, i.e. recognition of face images that are out of the image plane. In this research work, a short literature survey of 2D techniques which are used to correct pose are discussed.The classification of these techniques is based on three categories, (1) Real-view based matching, (2) Image space pose transformation and (3) Feature space pose transformation. This paper discuss the types of databases used, approaches to correct pose, the types of features extracted.
3D mapping and photogrammetry sensor payload for unmanned aerial vehicles
(2023-11) Purdon, Kyla; Van Niekerk, T; Phillips, R; Marais, Stephen T
Unmanned Aerial Vehicles (UAVs) have shown great potential for data collection and monitoring of areas. Sensors such as LiDARs and cameras can be used on UAVs for high-resolution data collection and used for various applications like Digital Surface Models (DSM), photogrammetry, inspection systems, and maintenance applications. This paper describes the design and implementation of a sensor payload for UAVs using a LiDAR sensor, camera, Inertial Measurement Unit (IMU), and Global Positioning System (GPS). The payload collects data that can be used to georeference LiDAR and camera data, which can later be used to generate a georeferenced map and perform object detection and classification.
3D physical model study for proposed remedial works to the Port of Richards Bay breakwaters
(2024-04) Wehlitz, Carl-Peter FV; Mabille, Eugene
The Port of Richards Bay is frequently subjected to extreme storm events where recorded wave heights can easily exceed five meters. Over the last two decades, these storms have caused significant damage to the port’s breakwaters. A 3D physical model study was commissioned with the objective to assess and verify the stability of four different strategies to repair and enhance the structural integrity of these structures. Results from this study showed that both breakwaters will ultimately fail if no major improvements to these structures are made. The repair options tested for the main breakwater included a comparison of two different toe designs, as well as comparing the performance of two different armour unit types. The outcome indicated that the repairs to the main breakwater will most likely entail a trenched toe design and an armour layer comprising of very large cubic-type blocks. While the repair options tested for the lee breakwater mostly entailed placing additional or larger armour units of the same type, it did allow the opportunity to optimise both the armour unit size and the coverage for an improved overall outcome.
3D Physical model study for the Haifa breakwater retrofit design
(2024-05) Wehlitz, Carl-Peter FV; Somlota, Lukhanyo L
Since 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.
A 3D potential field model of the Pilanesberg Complex shape and structure
(2013-10) Lee, SA; Webb, SJ; Jones, MQW; Durrheim, RJ; Ganerød, M
The Mesoproterozoic Pilanesberg Complex, South Africa, is the world’s largest alkaline intrusion. While surface field relationships suggest an inward dipping structure, it is unclear how these dips extend to depth. The 3D geometry of the Pilanesberg Complex is also unknown. 2D and 3D forward and inversion modelling of gravity and magnetic data are used to set limits on the 3D shape of the Complex. Based on age and chemical affinity, it is known that the Pilanesberg Complex forms part of a larger system of alkaline intrusions that includes two dyke swarms that radiate to the north-west and south of the Complex, as well as smaller circular clinopyroxene intrusions throughout the Bushveld Complex. The Pilanesberg dyke swarms and the circular clinopyroxenite intrusions are reversely magnetised to that of the normally magnetised Pilanesberg Complex, suggesting that a magnetic reversal occurred during emplacement of the system.
3D primary grain shapes resulting from semi-solid metal processing
(2017-07) Curle, Ulyate A
The issue regarding globular grain shape and size has been a topic for semi-solid processing since the discovery of the technique. Semi-solid rheo-processing takes advantage of cooling a liquid metal alloy to the solid + liquid phase field, while it is subjected to some form of turbulence during cooling. It has been suggested that the grains grow into spherical globules by observations of 2D microstructures. It is also known that reducing the melt super-heat has the effect of reducing the globule (grain) size. Are these 2D globules also spherical in shape in 3D or are these 2D shapes remnants of the 3D shapes after sectioning along planes? An Al-Si-Mg alloy is semi-solid processed using a patented processing coil that induces contactless stirring while simultaneously being cooled. Primary aluminium grains are extracted by an etch technique from a sample volume of the casting. The grain size distribution and shapes are analysed. The 3D particles are pictured with scanning electron microscopy. Various interesting particle shapes are observed, from simple to complex. The particle geometry in 3D is compared to 2D optical light microscopy micrographs. It is found that the 2D globules are remnant shapes from the 3D particles after sectioning along random planes.
3D Tyre/Road pavement contact stress measurements
(2010-10) De Beer, Morris
The CSIR’s proprietary Stress-in-Motion (SIM) measurements provide rational descriptions of 1D, 2D and 3D tyre/road pavement stresses for: Road pavement design testing and evaluation, as well as tyre design, testing and evaluation.
3D visual analysis tool in support of the SANDF's growing ground based air defence simulation capability
(2007-10) Duvenhage, B; Delport, JP; Louis, A
A 3D visual analysis tool has been developed to add value to the SANDF's growing Ground Based Air Defence (GBAD) System of Systems simulation capability. A time based XML interface between the simulation and analysis tool, via a TCP connection or a log file, allows individual simulation objects to be wholly updated or partially modified. Live pause and review of the simulation action is supported by employing data key frames and compressed XML for enhanced performance. An innovative configurable filter tree allows visual clutter to be reduced as required and an open source scene graph (OpenSceneGraph) manages the 3D scene representation and rendering. A visualisation capability is developed for the effective presentation of the dynamic air defence system behaviour, system state transitions and inter-system communication. The visual analysis tool has successfully been applied in support of system performance experiments, tactical doctrine development and simulation support during training and live field exercises. The 3D visualisation resulted in improved situational awareness during experiment analysis, in increased involvement of the SANDF in experiment analysis and in improved credibility of analysis results presented during live or after action visual feedback sessions.
3D, parallel fluid-structure interaction code
(2011-01) Oxtoby, Oliver F; Malan, AG
The authors describe the development of a 3D parallel Fluid–Structure–Interaction (FSI) solver and its application to benchmark problems. Fluid and solid domains are discretised using and edge-based finite-volume scheme for efficient parallel computation, with a hybrid of node- and element-based strains calculated in the solid model for accuracy. The Pressure-Projection Artificial Compressibility Split (PACS) algorithm [1] is used in the fluid domain and re-derived in an Arbitrary- Lagrangian–Eulerian (ALE) reference frame. A preconditioned GMRES algorithm is developed for matrix-free solver acceleration. The fluid and structural domains are strongly coupled with a fast mesh-movement technique employed in the fluid domain. The solver is parallelised for distributed-memory architectures.
4-RRS PKM for stabilisation on a mobile sensor platform
(2023-11) Ramruthan, Kshir; Kuchwa-Dube, C
Disturbances experienced by an inspection robot can reduce the quality of its sensor measurements, which can in turn negatively affect the robot’s functionality. This research aimed to design a Parallel Kinematic Mechanism (PKM) for use as a stabilisation mechanism. The research focused on designing, simulating, building, testing, and analysing the mechanism. The PKM was modelled and simulated using MATLAB®, designed and developed using NX CAD software, and it was tested using a custom-built test rig that could simulate rotational disturbances. Using the metric of absement, the PKM significantly reduced the disturbances, depending on the disturbance induced.
4G RAN infrastructure sharing by 5G virtualized mobile network operators: A tutorial
(2021-09) Mamushiane, Lusani; Mboweni, Lawrence S; Kobo, Hlabishi; Mudumbe, Mduduzi J; Mwangama, J; Lysko, Albert A
Active radio access network (RAN) infrastructure sharing has emerged as a promising solution for efficient spectrum utilization, capital and operational cost savings, improved MVNO penetration rates and lower broadband retail prices in both emerging and developed markets. This paper presents a tutorial on the testbed implementation of an active RAN sharing architecture, leveraging multi-vendor virtualized 5G and 4G core networks running on commodity hardware and proprietary 4G RAN equipment (eNodeB). Troubleshooting techniques used for different implementation challenges encountered are also presented in this contribution. The performance of the proposed architecture was validated using end-user quality of experience (QoE) as the key performance indicator. The results show no performance degradation when RAN sharing is being utilized.
5G core network load testing traffic generator: Emulating real-world traffic scenarios
(2026-12) Mukute, T; Lysko, Albert A; Mwangama, J
This paper introduces the Core Network Traffic Generator, a comprehensive performance evaluation and compliance testing tool for 5G core networks that addresses significant limitations in existing solutions. Our tool uniquely combines control plane and data plane traffic generation with high-precision performance metrics collection. Built on well-established projects, pycrate for protocol message handling and eBPF/BCC for kernel-level monitoring, it collects SCTP transport metrics with sub-microsecond precision—a capability absent in current tools. Key features include simultaneous emulation of gNodeB and multiple UEs, granular 5G procedure timing analysis, detailed SCTP performance visualisation, and automated compliance validation against 3GPP standards. Validated with major open-source implementations (Open5GS, free5GC, OAI) and proven in research publications, the system operates on commodity hardware and is available under the MIT license, offering an accessible yet powerful solution for both academic research and operational network testing.
5G network slice resource overbooking: An opportunity for telcos to boost their revenue
(2022-08) Mamushiane, Lusani; Mwangama, J; Lysko, Albert A; Kobo, Hlabishi I
The global impact of COVID-19 has been unprecedented, with over-the-top (OTT) services consumption growing at a staggering rate. While OTT does consume revenue-generating data, OTT services are gradually substituting the traditional primary sources of revenue, voice and SMS services, with “freemium-based” alternatives such as WhatsApp and Telegram. This has driven telcos to reconsider their strategies and revenue sources. We believe that 5G network slicing (a type of 5G infrastructure sharing) is a potential solution that telcos could adopt to boost their revenue. In particular, this paper introduces the concept of network slice resource overbooking. We consider leveraging machine learning (ML) to maximise network resource utilisation which translates to maximum revenue gains for telcos. The concept of overbooking is unique and novel in network slicing. To realise this objective, we intend to build a mathematical model of the overbooking strategy, and integrate the model into a resource orchestration platform for evaluation on an emulated 3GPP (Release 16) compliant 5G testbed.
5G-enabled automated plant watering system for small farmers using srsRAN and Open5GS
(2026-07) Gumbi, Zekhethelo S; Mtsotso, Steve; Mamushiane, Lusani; Kobo, Hlabishi I
Smart irrigation systems rely on sensing, automation, and communication to improve water-use efficiency and reduce manual intervention. In rural South Africa, however, small-scale farmers continue to face persistent constraints including water scarcity, prolonged dry seasons, limited digital connectivity, and increasing irrigation energy costs, which obstruct the adoption of precision irrigation technologies. This paper presents an automated plant watering system implemented over an opensource private 5G standalone (SA) network using srsRAN and Open5GS. The proposed system integrates soil moisture and environmental sensing, threshold-based irrigation control, and real-time communication between a low-cost sensing node and a Python-based edge application server. In the deployed architecture, the sensing and actuation node connects via Wi-Fi to a 5G user equipment (UE), which provides broadband access to the private 5G network. The system is experimentally evaluated using both network-level and application-level performance measurements. The private 5G testbed achieved round-trip time (RTT) between 19.557 ms and 159.896 ms, uplink throughput of 16.4 Mbps, downlink throughput of 50.9 Mbps, and zero packet loss during testbed evaluation. During application operation, end-to-end RTT ranged from approximately 60 ms to 170 ms for local operation and increased beyond 300 ms when a cloud-based monitoring platform was introduced. The results show that open-source private 5G SA infrastructure can support responsive smart irrigation services while providing a practical and affordable platform for experimentation and pilot-oriented deployment. This study contributes experimental evidence for broadband-based smart irrigation over private 5G SA, an area that remains relatively underexplored compared with low power wide area network (LPWAN) agricultural Internet of Things (IoT) approaches.

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