- ItemICP-MS analysis of trace metals in pacific oysters (Crassostrea gigas) within the port of Saldanha, South Africa(Stellenbosch : Stellenbosch University, 2022-12) Dhlalani, Nomcebo Marry; Bezuidenhout, J.; Stellenbosch University. Faculty of Military Sciences. School of Science and Technology. Dept. of Physics.ENGLISH ABSTRACT: The aim of the study was to monitor the accumulation of the trace metals, Manganese(Mn), Cadnium (Cd), Zinc (Zn), Copper (Cu) and Mercury (Hg) in oysters that were cultivated in Saldanha Bay over the period 2018 until 2020. Eight strategic positions were selected in Saldanha Bay for biomonitoring; three at the oyster growers lease areas in Small Bay, one at the oyster growers lease areas in Big Bay and four close to the Multi-purpose Terminal. At each monitoring station a cohort tower was deployed which contained the oysters used for biomonitoring. At most, ten of these oyster spat were selected and assessed for trace metal content to establish a baseline condition to measure trace metal accumulation. The oysters were analysed for trace metal content over long- and short-term intervals. Long-term monitoring entailed deploying the long-term oyster cohort for a total period of 24 months. After every three months of deployment, the oyster towers were retrieved and a sample of five oysters was selected from the long-term cohort, placed in a labelled plastic bag, and sent for analysis. The short-term monitoring, on the other hand, entailed deploying a fresh oyster cohort every three months over a period of 24 months. After three months of deployment, the oyster tower was retrieved and a fresh batch of oyster tower was replaced in the same sampling point for both long-term and short-term intervals. The samples of both long-term and short-term monitoring were sent to the ICP-MS laboratory, University of Stellenbosch, where tissue was extracted from the oysters, frozen and submitted for trace metal analysis using an Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). It was found that the average concentration of Mn ranges between 1.14 mg/kg and 1.80 mg/kg and Zn ranges between 55.45 mg/kg and 97.90 mg/kg. It was assumed that the anti-fouling products used in the Small Bay influenced the concentration of Cu, which gave high values ranging from 2.18 mg/kg up to 4.49 mg/kg. Concentration of Cd range from 0.75 mg/kg to 1.20 mg/kg and Hg was between 0.00 mg/kg and 0.01 mg/kg. When looking at short-term trends, generally after deployment, oysters recorded an increase in concentrations for the following metals, Mn, and Zn, while Hg, Cu, and Cd recorded a general decrease in concentrations over the same short-term deployments. Not all general trends were omnipresent as spatial and temporal specific variations were observed during the study. This suggested that in some cases trace metal supply intake coupled with seasonal variation could influence the amount of trace metal present in the oyster at any time. The average trace metal concentrations in oysters presented were in a decreasing trend of Zn > Cu > Mn> Cd > Hg. The oyster proved to be good biomonitors due to its ability to accumulate trace metals over time. There were however, oyster mortalities over the period of the study, but these mortalities were related to parasitic infections.
- ItemModelling the impact of Magnetohydrodynamics (MHD) nanofluid flow on cooling of engineering systems(Stellenbosch : Stellenbosch University, 2021-12) Tshivhi, Khodani Sherrif; Makinde, Oluwole Daniel; Stellenbosch University. Faculty of Military Sciences. School of Science and Technology.ENGLISH ABSTRACT: The flow investigations regarding nonlinear materials are extremely important in the applied science and engineering areas to explore the properties of flow and heat transfer. Recent advancement in nanotechnology has provided a veritable platform for the emergence of a better ultrahigh-performance coolant known as nanofluid for many engineering and industrial technologies. In this study, we examine the influence of a magnetic field on the heat transfer enhancement of nanofluid coolants consisting of Cu-water, or Al2O3-water, or Fe3O4-water over slippery but convectively heated shrinking and stretching surfaces. The model is based on the theoretical concept of magnetohydrodynamics governing the equation of continuity, momentum, energy, and electromagnetism. Based on some realistic assumptions, the nonlinear model differential equations are obtained and numerically tackled using the shooting procedure with the Runge-Kutta-Fehlberg integration scheme. The existent of dual solutions in the specific range of shrinking surface parameters are found. Temporal stability analysis to small disturbances is performed on these dual solutions. It is detected that the upper branch solution is stable, substantially realistic with the smallest positive eigenvalues while the lower branch solution is unstable with the smallest negative eigenvalues. The influence of numerous emerging parameters on the momentum and thermal boundary layer profiles, skin friction, and Nusselt number are depicted graphically and quantitatively discussed.
- ItemAssessing public participation strategies in people’s housing process in Wallacedene(Stellenbosch : Stellenbosch University, 2020-12) Sandile, Unathi; Theron, Francois; Stellenbosch University. Faculty of Military Science. Dept. of Science and Technology.ENGLISH ABSTRACT: Public participation is important in housing development. Since the start of democratic government in South Africa, local governments have been encouraged to promote and use public participation to empower its citizens to influence, direct, control and own their development initiatives. In this study the researcher assessed public participation strategies in Nomzabalazo People’s Housing Process in Wallacedene (NPHPW). The study assesses the public participation process applied and relevant strategies used in a housing development programme in the community, and to establish whether public participation in housing development in this area is practiced as local governance legislation suggests. The study also aims to establish how the selected public participation strategies used affect housing development, in particular assess if housing beneficiaries can actually “influence, direct, control and own” the housing project. In addition, the study aims to establish whether the COCT creates an enabling environment for authentic and empowering public participation for housing beneficiaries on matters that affect their lives. Furthermore, the study evaluates public participation by the members of the public particularly beneficiaries in housing development by assessing the public participation strategies used during the housing planning and delivery in Wallacedene, using the International Association for Public Participation (AIP2) Spectrum model and Arnstein’s (1969) ladder typologies.
- ItemInvestigating e-commerce adoption in the procurement processes of the Botswana Defence Force : a qualitative study(Stellenbosch : Stellenbosch University, 2007) Moswetsi, William; Botha, D.; Stellenbosch University. Faculty of Military Science. Dept. of Science and Technology.ENGLISH ABSTRACT: This study sets out to explore the factors that affect e-commerce adoption in the Botswana Defence Force (BDF) procurement process. The factors that were identified as affecting e-commerce adoption emerged from studies conducted mainly in the context of the developed world, particularly the Western world. Discussions in the academic literature therefore appear to be based on assumptions that do not necessarily apply to the developing world. This study explores these factors in an organisation in a developing country. The purpose of the study was to develop a rich picture of the factors that affect ecommerce adoption in the BDF procurement process. The study aimed to identify issues, factors, and problems critically involved in IT adoption in the BDF procurement process and to develop a theory that could help to understand these factors. Grounded theory methodology was the chosen method of qualitative data collection and analysis. This methodology was chosen because it facilitates inductive theory generation from an interpretive perspective. This approach was suitable for the study as the aim was to develop a theory that was grounded in the data and likely to resemble reality. The data was gathered through semistructured interviews with procurement officers, IT officers, and BDF senior officers. The research findings identified the benefits, limitations, drivers and barriers of ecommerce adoption in the BDF procurement process. The technological capabilities of the BDF were identified and it was concluded that the BDF is prepared in terms of IT infrastructure for e-commerce adoption. A theory of the factors affecting e-commerce adoption was developed using grounded theory methodology and a model of the factors affecting e-commerce adoption in the procurement process was developed. To strengthen the theory that was 'built', it was compared to previous e-commerce adoption literature. Overall, this research provided a stepping stone for new research into ecommerce adoption in the Botswana Defence Force. It has facilitated better understanding of how participants view e-commerce adoption in the BDF. The study also contributes to the literature on e-commerce adoption, which is currently under-researched, particularly in developing countries such as Botswana.