https://ir.unisa.ac.za/handle/10500/2910 Mon, 10 Aug 2026 18:04:41 GMT 2026-08-10T18:04:41Z https://ir.unisa.ac.za/handle/10500/32797 Enhancing water utility bulk meter reading through lot retrofit : a reliable and energy efficient wireless solution : the Rand Water case study in South Africa Dlamini, Advisor Mlungisi Water is a scarce resource and appropriate smart bulk water metering and leakage detection are crucial. Current smart bulk water metering methods at Rand Water in South Africa are moving from being essentially manual to being automated. However, the currently used methods remain operationally costly, energy inefficient and not so reliable in terms of their employed communication approaches. This often leads to suboptimal resource allocation. Additionally, most of these bulk water meters are enclosed within concrete chambers and are at mostly at low elevation or even underground. This poses a problem in terms of identifying an efficient wireless solution for remote reading and site security. This study investigates and evaluates the performance of an appropriate Internet of Things (IoT) solution capable of reliably and in an energy efficient manner sending bulk water meter readings to a remote server for processing. The proposed solution can overcome the identified low elevation and penetration issues. It also detects possible water leakages, water chamber overflow, burst detection and any kind of site tampering in the form of alarms to ensure timely response and reduced operational cost. This study employs a simulation-based methodology using MATLAB to develop and evaluate deployment-aware models for both LoRaWAN and NB-IoT protocols, specifically incorporating the effects of reinforced concrete attenuation, low antenna elevation, and join/rejoin dynamics. This approach consists of a wireless communication feasibility study of the existing water utility infrastructure, followed by the implementation of identified low-power wide area network (LPWAN) IoT protocols suited for the application and the performance evaluation and comparison of the identified LPWAN IoT technologies in terms of energy efficiency and communication reliability. The results obtained from the proposed approach demonstrate that NB-IoT achieves superior reliability, maintaining packet delivery ratios above 0.96 even under severe concrete penetration losses up to 30 dB, while LoRaWAN exhibits a sharp degradation in reliability below 0.85 beyond 20 dB attenuation. Conversely, LoRaWAN offers better energy efficiency and extended battery lifetime under moderate conditions, whereas NB-IoT trades higher energy consumption for predictable and robust packet delivery. These findings support a deployment-aware, hybrid technology selection strategy for large-scale underground bulk water metering applications. Thu, 15 Jan 2026 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/32797 2026-01-15T00:00:00Z https://ir.unisa.ac.za/handle/10500/32718 Modeling of the solar radiation output in the Democratic Republic of Congo Lusamba Yangindu, Dieudonné The Democratic Republic of Congo is not only a geological contrast but also an energy contrast, as it possesses a great hydroelectric potential capable of satisfying its own needs and those of many African countries. However, according to the most optimistic studies, the electrification rate in the Democratic Republic of Congo is less than 19%. Photovoltaic solar energy therefore represents a viable solution to help meet national energy needs. Accurate knowledge of solar irradiance is essential for proper sizing and optimization of photovoltaic systems. This study aims to establish general statistical models to predict solar irradiance (kWh/m²/day) as a function of sunshine duration (h/day) for any province of the Democratic Republic of Congo. Global solar irradiance data were obtained from RETScreen through the Renewable Energy Atlas of the DRC, while sunshine duration data were collected from the European Centre for Medium-Range Weather Forecasts. Five models (linear, quadratic, cubic, logarithmic, and exponential) were developed using the least squares method and validated using normalized statistical errors (NMAE, NMBE, NRMSE), the Nash–Sutcliffe efficiency criterion (NS), and the coefficient of determination (R²). Two scenarios were analyzed: scenario 1: excluding the provinces of Nord and Sud Kivu, and scenario 2: including these provinces. By excluding these provinces, the quadratic and cubic models explained 88% and 93% of the relationship between annual average sunshine duration and solar irradiance, respectively. Including them reduced performance, with R² ≈ 0.70, indicating that additional climatic variables may be required. A national sunshine duration heat map identifying four main exposure zones was also produced, supporting photovoltaic planning across the Democratic Republic of Congo. Wed, 01 Apr 2026 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/32718 2026-04-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/32667 The potential of epoxy coated chicken feathers as modified natural fiber in concrete Rikhotso, Mixo Asset This study assessed the viability of incorporating both untreated (UCF) and treated chicken feathers (TCF) into concrete to enhance sustainability in the construction industry. Five concrete mixes were tested, with Mix 4 (0.75% TCF) and Mix 5 (1.25% TCF) emerging as the most promising. These mixes showed improved workability and retained high compressive and tensile strength compared to the control. In contrast, the mix with 1% UCF exhibited significant reductions in mechanical and durability performance. Durability tests confirmed that TCF-enhanced concrete maintained resistance to oxygen permeability, water absorption, and chloride penetration, while also displaying reduced shrinkage. Overall, treated feathers proved to be a suitable partial replacement in non-structural concrete applications, offering both environmental and engineering benefits. Text and abstract in English Sun, 01 Jun 2025 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/32667 2025-06-01T00:00:00Z https://ir.unisa.ac.za/handle/10500/32631 Geotechnical analysis of dolomitic terrain to assess the probability of sinkhole formation : a case study of Centurion, South Africa Mavhetha, Lavhelesani Dolomitic terrain in the Gauteng Province of South Africa presents significant geotechnical challenges for urban development. This is primarily due to subsurface dissolution processes that create void networks susceptible to sinkhole formation and ground subsidence. This research study explores the case of Cornwall Hill in Centurion where numerous sinkhole incidents have caused infrastructure damage and imposed severe development constraints. A multi-method investigation approach was employed, combining gravity geophysical surveys, test pit excavations, rotary percussion boreholes, dynamic cone penetrometer tests, and laboratory analysis. Gravity surveys comprised 105 measurement stations on a 50 m × 50 m grid. Five test pits were excavated while four rotary percussion boreholes were drilled to depths between 10 and 25 m. Five dynamic cone penetrometer tests were also carried out on site and rotary percussion drilling was done to complement gravity surveys. Lastly, a comprehensive laboratory geotechnical analysis programme was done on field samples collected on site. Results revealed that the site is underlain by Malmani Subgroup dolomites overlain by a consistent three-layer stratigraphic sequence comprising colluvium, residual soil, and dolomite bedrock. The residual soils exhibited consistent classification as low plasticity clay with plasticity indices of 11 – 14% and a gravel-rich composition at 50 – 60%. However, the soils displayed significant spatial variability in thickness (0.70 – 2.70 m) and bearing capacity (152 – 320 kPa at 0.7 – 0.8 m depth). Rotary percussion drilling confirmed the presence of shallow competent dolomite beneath chert layers at 2 m depth and colluvium overlying interbedded chert and dolomite from 3 m depth. A cavity located within the peripheral low-density gravity zone and extending from 2 m to 13 m depth before competent material was also reached. Gravity survey results defined the subsurface density contrast, with high-density areas (covering 60% of the site) indicating shallow competent bedrock at 1.0–1.6 m depth and low-density areas (covering 40% of the site) indicating deep weathering profiles exceeding 2.7 m; the cavity intersected in BH01 directly correlates with low gravity in the peripheral zone. The site was described into Zone A (central D3 area of the site suitable for development with raft foundations at 600–900 mm depth) and Zone B (peripheral D4 area of the site unsuitable for development owing to the presence of a cavity, gravity lows indicating solution features, and high collapse potential) based on the results of integrated geophysical, intrusive, and laboratory investigation. The study meets the requirements of SANS 1936-2:2012 and proves the potential of integrated characterization of complex terrain, including the application of Rotary Percussion Drilling (RPD) as ground truth, for making informed decisions regarding development of difficult terrain such as this dolomitic environment, while providing valuable geotechnical data for the Centurion region. Tue, 19 May 2026 00:00:00 GMT https://ir.unisa.ac.za/handle/10500/32631 2026-05-19T00:00:00Z