VUT DigiResearch

DigiResearch is the VUT electronic open access archive. Its purpose is to collect, distribute and preserve the research performed by the VUT research community.

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Smart lighting control system for energy efficient public lighting
(Vaal University of Technology, 2022-08) Manyake, Moabi K.; Otunniyi, Temidayo, Dr.; Mathaba, Tebello, N. D., Dr.
Public Lighting System (PLS) infrastructure is a significant energy consumer within cities and an important part of the maintenance budget. Multiple Smart Public Light Management Systems (S-PLMSs) based on the Internet-of-Things (IoT) is being proposed in recent literature as a way of improving energy efficiency in PLSs. This work presents an analysis, a design and cost assessment of a S-PLMS design. The analysis begins with a literature review of technologies and techniques applicable within S-PLMSs using a generic 3-tier IoT based architectural framework. The 3-tier IoT framework is used to develop a comprehensive taxonomy of S-PLMSs for each of the three layers, perception & control tier, communication tier and application tier. A S-PLMS design entailing dimmable LED luminaires remotely controlled using a wireless LoRa-based technology sensor network is proposed. An aspect of the design is prototyped and simulated using the Arduino platform. A street lighting design case study is carried out for a street in Emfuleni Local Municipality. Cost assessment study reveals that retrofitting this street with the new design would result in a 38.6% reduction of energy-cost savings. However, should the traffic be restricted to 200 vehicles and 600 vehicles per hour, then the estimated energy reduction would be 75.8% and 54.5%, respectively.
Process mineralogy for the physical beneficiation of a low-grade nickel laterite bearing ore
(Vaal University of Technology, 2024) Jeli, Ntsontso Edward; Motsetse, C. K., Dr.; Mendonidis, P., Prof.
Nickel is one of the world's most important base metals with a widespread use in numerous industrial processes accounting to a consumption of about 2 million tons yearly. Ni sources include sulphide ore with average grade of 2 wt % and laterite ores with average grade of 0.4 wt%, 60% of the worlds nickel production is from the sulphide ores which constitute 30 % of the world’s reserves and Ni laterite ores contain about 70 % of the worlds nickel reserves and contributes approximately 40 % towards nickel production. The depletion of high-grade Ni sulphide ores has led to the exploration of low-grade Ni laterite ores as an alternative source for nickel production. Liberation and beneficiation of from laterite ores requires an understanding of the ore mineralogy so as to establish the liberation particle size and suitable beneficiation method. In sulphide ores, nickel is concentrated in sulphide minerals that can be beneficiated using conventional metallurgical methods, however in laterite ores nickel is finely disseminated in silicate and oxide minerals thus making liberation and processing by conventional methods it difficult. In this study, a nickel bearing silicate ore was studied for nickel beneficiation. XRD and bulk modal analysis showed that the ore contained silicate minerals, amphibole (40.34 %), chlorite (30.43 %), talc (11.52 %), quartz (8.76 %) and plagioclase (5.6 %). Ni deportment analysis by EPMA and QEMSCAN showed that the nickel is present in two particular silicate minerals, amphibole and chlorite. Grain size analysis on the ore showed that amphibole had a coarser average grain size than chlorite. Liberation analysis shows that amphibole is less liberated than chlorite, with the percentages of fully liberated particles being 36.21 % and 48.29 %, respectively. The head sample was crushed and ground to produce three size fractions of -212 μm +125 μm, -125 μm +75 μm, and -75 μm. The three size fractions were classified using the Falcon Concentrator. The effect of G-force was studied at 30 G, 45 G and 60 G, the effect of percentage solids at 10 %S, 20 %S and 30 %S, and the effect of both G-force and percentage solids at 10%S - 30 G, 20 %S- 45 G and 30 %S - 60 G. Samples collected from the falcon concentration test were dried and prepared for mineralogical and chemical analysis. The optimum conditions for the physical beneficiation of the ore were observed at a size fraction of -75 μm at 10 %S and speed rotation G-force of 30 G, the mass distribution to the underflow and overflow points were obtained at 63.25 % UF and 36.75 % OF, respectively. The reprocessing of the -75 μm underflow material was conducted to recover more mass to the overflow. The optimum conditions for the physical beneficiation of the ore were observed at a size fraction of -75 μm at 10 %S and speed rotation G-force of 30 G, the mass distribution to the underflow and overflow points were obtained at 63.25 % UF and 36.75 % OF, respectively. The reprocessing of the -75 μm underflow material was conducted to recover more mass to the overflow.
Determining hygiene and safety practices of students during culinary studies skills practicals in a university of technology
(Vaal University of Technology, 2023-12-11) Kangala, Ntshengedzeni Patience; Dicks, E. G., Prof.; Kearney, J. E., Prof.
BACKGROUND: Foodborne diseases (FBDs) are a major public health concern and a significant cause of global morbidity and mortality. FBDs include a wide range of illnesses resulting from consumption of foodstuffs contaminated with toxic microorganisms or chemicals. Elimination of diseases is a key anchor of achieving long-term health outcomes and ensuring accessible and equitable health for millions of South Africans. The study was conducted to determine hygiene and safety practices of students during culinary studies skills practicals in a university of technology as they will play a major role in prevention of FBDs in future. AIMS: The main objective of this study was to determine the hygiene and safety practices of University of Technology (UOT) foodservice management students from first- to third-year level in the culinary studies skills practical classes, in order to design hygiene and safety assessment rubric for culinary studies skills practical classes. METHODOLOGY: Quantitative observation design method was followed. The researcher developed and pre-tested a checklist to collect the data. Data was captured on Microsoft Excel and analysed on the latest version of SPSS. Analysis of variance (ANOVA) was used to test results in and between the groups. The results were described using frequency counts and percentages. RESULTS AND DISCUSSION: Generally, students observed during the conduct of this study achieved high scores across all these categories. However, low scores were also observed in certain areas such as mopping and sweeping simultaniously (dry cleaning), wearing of necktie, sanitising displaying appropriate signage while conducting cleaning operations of the cullinary skills class. CONCLUSIONS: The study has concluded that the foodservice management students at the UOT have in general maintained food safety standards. Further, the COVID 19 pandemic provided a good context for the study and highlighted the importance of general hygiene and food hygiene in particular. RECOMMENDATIONS: A high priority should be given to individual, institutional and environmental factors hindering food safety at the UOT. UOT must build a sustainable Food safety culture (FSC) to support its various food safety initiatives, and further research should be done regarding students’ attitudes towards food safety cultural belief systems.
Quantum Adsorption’s Mechanism of Gelatin-Cellulose Hydrogel for Effective Removal of Copper and Cobalt ions from Wastewater using Artificial Neural Network
(Vaal University of Technology, 2023-01) Lukusa, Kabeya Tresor; Mutombo, Emery Kalonda, Prof.; Tshilenge, John, Kububa, Prof.
Heavy metal ions are one of the most toxic materials in the environment. Adsorption is the most used process for the removal of heavy metals from wastewater because is recognized as economical, effective and versatile method. Much research has been conducted into processes to remove heavy metals using different adsorbents. Various adsorbents have been used to remove harmful heavy metal ions from wastewater. Zeolite, clay, activated carbon and biopolymers are the most common adsorbents used. Due to complex nature on adsorption process, ANN (Artificial Neural Network) have been found to be one the most promising numerical simulation techniques to make reliable predictions. In order to obtain extensive information on the adsorption process of metal ions on the functional groups of adsorbents, quantum adsorption mechanism was investigated using DFT (Density Functional Theory). In this study, n-GCHM and GCHM@Fe3O4 were used to remove Cu(II) and Co(II) metal ions from laboratory-prepared synthetic wastewater. Batch experiments were conducted to obtain the optimum conditions for the Cu(II) and Co(II) metal ions. The effect of parameters such as pH, contact time, and initial concentration were also determined. The optimal conditions found were 120 minutes of contact time and a pH of 5. The maximum adsorption capacity of Cu(II) and Co(II) was 5.8343 mg/g and 4.7148 mg/g, respectively using n-GCHM while that using GCHM@Fe3O4 the monolayer capacity was 4.7148 mg/g for Cu(II) and 8.1499 mg/g for Co(II). The high percentage removal of Cu(II) was 70.5% with n-GCHM and 89.4% for Co(II) with GCHM@Fe3O4, all to the pH 5. The experimental data fit well to Pseudo-first-order kinetic and Freundlich isotherm models for both metal ions. The experimental data conformed adequately to the film diffusion model for both metal ions at pH 5 with n-GCHM, but the Co(II) results fit well to the particle diffusion model with GCHM@Fe3O4. The molecular orbital approach (MOs) has shown that the HOMO and LUMO was located on the arginine (-NCN-) and LUMO on glutamine (-NCO-). The quantum adsorption mechanism has shown that the binding energy of Cu(II) and Co(II) on imine functional group (arginine) was of -60604.399 eV and -53649.06 eV, respectively. On -NCO- functional group (glutamine), the binding energy was of -58587.608 eV and -51632.618 eV, respectively for Cu(II) and Co(II).
Exploring the adoption of social media as a reputation management tool in crisis communication: The case study of an institution of higher learning
(Vaal University of Technology, 2024-03) Mafatle, Mahlapane Lydia; Manana, K. P. P.; Mbatha, Blessing, Prof.
The study aimed to explore the role of social media during a crisis at a higher education institution, and how social media is used to manage reputation. The study had three objectives: to investigate the role of social media in crisis communication at a higher education institution, to examine the types of social media used in crisis communication at the institution, and to explore the benefits and challenges of using social media for reputation management. A qualitative approach was adopted, and data was collected through focus group discussions with students and senior managers from the Communications Department, who were selected using purposive sampling. Thematic analysis was used to analyse the data, with the researcher transcribing all recorded data. The study found that various social media platforms were utilised, including Facebook, Twitter, LinkedIn, institutional websites, Flickr, Instagram, and YouTube. It also found that social media platforms played a crucial role in enhancing work productivity and creativity. Furthermore, social media was used for information dissemination and quick communication with university stakeholders. The institution used social media as a tool for managing reputation by ensuring the dissemination of relevant information to stakeholders. Additionally, social media played a fundamental role in attracting prospective students and transforming the way information is disseminated by the institution. However, there is still room for improvement.