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Item 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, HThe 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]Item 1st review of the status of national air quality: 1994-2004(2006-10) Taviv, I; Zunckel, M; Mahema, T; John, Juanette; Naidoo, MogeshNeed for informed decision making, history of fragmented and un-coordinated monitoring, framework for NAQIS-SAAQIS (output of NAQMPII) and metadata collection (output of NAQMPII).Item 2 DOF resolution adjustment laser position sensor(Massey University, 2008-12) Shaik, A; Tlale, NS; Bright, GA 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.Item 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 PThe 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.Item 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, BFThe 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.Item 25m2 target-aligned heliostat with closed-loop control(2007-09) Roos, TH; Zwane, NX; Kruger, E; Perumal, S; Cathro, RA 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.Item 2D Methods for pose invariant face recognition(IEEE, 2016-12) Mokoena, Ntabiseng; Djonon Tsague, Hippolyte; Helberg, AThe 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.Item 3D mapping and photogrammetry sensor payload for unmanned aerial vehicles(2023-11) Purdon, Kyla; Van Niekerk, T; Phillips, R; Marais, Stephen TUnmanned 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.Item A 3D potential field model of the Pilanesberg Complex shape and structure(2013-10) Lee, SA; Webb, SJ; Jones, MQW; Durrheim, RJ; Ganerød, MThe 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.Item 3D primary grain shapes resulting from semi-solid metal processing(2017-07) Curle, Ulyate AThe 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.Item 3D Tyre/Road pavement contact stress measurements(2010-10) De Beer, MorrisThe 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.Item 3D visual analysis tool in support of the SANDF's growing ground based air defence simulation capability(2007-10) Duvenhage, B; Delport, JP; Louis, AA 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.Item 3D, parallel fluid-structure interaction code(2011-01) Oxtoby, Oliver F; Malan, AGThe 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.Item 4-RRS PKM for stabilisation on a mobile sensor platform(2023-11) Ramruthan, Kshir; Kuchwa-Dube, CDisturbances 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.Item 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 AActive 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.Item 5G network slice resource overbooking: An opportunity for telcos to boost their revenue(2022-08) Mamushiane, Lusani; Mwangama, J; Lysko, Albert A; Kobo, Hlabishi IThe 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.Item 84th IMESA Conference in collaboration with IAWEES (International), Virtual conference, Cape Town, 17 - 19 November 2021(2021-11) Steyn, Maronel; Walters, Chavon RWater scarcity, increased pollution, unprecedented population growth and climate change are collectively driving the need to reuse water with the aim to enhance water security, sustainability, and resilience. It is clear that South Africa¿s already strained water resources will become even more stressed in the near future. The Department of Water and Sanitation predicted that by 2030 water demand will reach 17.7 billion m3, far more than what is available to allocate. An Atlas for potential industrial bulk scale water reuse was produced from publicly available Natsurv and WARMS data. A web-based Decision Support System (DSS) tool is being developed to enable municipal and industry partners, and water quality managers to make informed decisions for possible reuse options. The tool aims to directly assist by linking industrial effluent volumes and quality to fitness for use, and linking it with specific industries in the geographical vicinity based on industry specific water quality and quantity requirements.Item 85 dBA: is it protective enough to prevent hearing loss in South African miners?(Southern African Institute of Mining and Metallurgy, 2009-09) Edwards, AThe Occupational Exposure Limit (OEL) for noise is legislated to be 85 dBA. However, owing to the energy of different frequencies the effect on the ear by sounds of different frequencies is known to vary. Also, there is recent evidence of the synergistic effect of chemicals and noise on the inner ear. Similarly, previous studies have shown that combined exposure to noise and exercise (workload) will cause greater cochlea stress than exposure to noise in isolation. A miner is not exposed only to noise in isolation. The environmental stressors that a miner may be exposed to simultaneously can include noise, heat and exercise, amongst others. The hypothesis is that the OEL which does not take into account complex exposure patterns may not provide adequate protection for miners’ ears. A pilot study to evaluate the impact on the inner ear used otoacoustic emissions as a measure of stress to the cochlea was undertaken. Controlled exposure to noise, heat and exercise on a group of young healthy males and females was conducted using less than the prescribed OEL for noise. Pre-exposure and post-exposure otoacoustic measurements were compared to evaluate the impact of individual and combined exposures. Statistically significant differences were found between the pre-exposure and post-exposure otoacoustic measurements for noise as a stressor. Exposure to other health stressors did not appear to accentuate the effect on the cochlea. The results appear to indicate that further investigation of the current OELs and the methods and aspects being measured is needed.Item ABox abduction in ALC using a DL tableau(ACM, 2012-10) Halland, K; Britz, KThe formal definition of abduction asks what needs to be added to a knowledge base to enable an observation to be entailed by the knowledge base. ABox abduction in description logics (DLs) asks what ABox statements need to be added to a DL knowledge base, to allow an observation (also in the form of ABox statements) to be entailed. Klarman et al [8] have provided an algorithm for performing ABox abduction in the description logic ALC by converting the knowledge base and observation to rst-order logic, using a connection tableau to obtain abductive solutions, and then converting these back to DL syntax. In this paper we describe how this can be done directly using a DL tableau.Item Abundance estimation of spectrally similar minerals(IEEE, 2009-07) Debba, PraveshThis paper evaluates a spectral unmixing method for estimating the partial abundance of spectrally similar minerals in complex mixtures. The method requires formulation of a linear function of individual spectra of individual minerals. The first and second derivatives of each of the different sets of mixed spectra and the individual spectra are determined, at signal-to-noise ratios of 50:1, 200:1 and 500:1. The error is minimized by means of simulated annealing. Experiments were made on several different mixtures of selected end-members, which could plausibly occur in real situations. The authors conclude that in the method proposed, the use of the original and first order derivatives provides a valuable contribution to unmixing procedures provided the signal-to-noise ratio is between 50:1 and 200:1. When the signal-to-noise ratio increases, the second derivative of the observed spectrum and the second derivatives of the end-member spectra give most precise estimates for the partial abundance of each end-member. This can often be seen when the signal-to-noise ratio is of the order 500:1.