3. Electronic Theses and Dissertations (ETDs) - All submissions

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A conceptual analysis for resource optimization in variable time multipurpose batch plants
(2020) Li, Zhiwei
Batch processing has been embraced by numerous chemical industries, such as the food, beverage, specialty chemical, and pharmaceutical industries because of its flexibility of accommodating changes in demand and responding effectively to uncertainties in market and supply chains. On the other hand, wastewater generated by batch processes depends on the specific tasks. Thus, the methods of wastewater minimization developed for continuous processes do not apply to batch processes. Few studies based on insight-based techniques have been reported to address wastewater recovery issues for flexible batch processes. The flexible batch process refers to that in which the durations of batch operations are treated as variables, not parameters. Therefore, a conceptual analysis was performed in this work to address the wastewater minimization in batch plants with flexible scheduling. A dynamic programming approach was first proposed to design a batch water network based on predefined scheduling. Insight from these results could assist the designer in rescheduling operations to maximize water recovery through direct water reuse. However, the extent of performance improvement is limited because the rescheduling process only involves a few operations, not all of the water operations. Thus, the dynamic programming method was extended to flexible batch processes in which only durations of batch operations are given. The difference is that in the former method, the stage is determined by the timings of water operations, while for the latter approach, the stages are identified based on the inlet concentration of water operations. Although dynamic programing approach, as an algebraic method, could provide a graphical representation of the targeting process, it is difficult to find the optimal solution when faced with complex problems. A match ranking matrix approach was proposed to prioritize matches between water sources and sinks. Batch water network could be synthesized by choosing optimal matches between water sources and sinks. Besides, a hybrid method of combing water pinch analysis and match ranking matrix method was presented to design batch water network, which takes advantages of graphical representation of pinch analysis and insight for the design of batch water network from match ranking matrix method. Finally, the main conclusions and future work are summarized. These conceptual methods in this work could be used to address the wastewater minimization in flexible batch plants.
Contestations surrounding the upgrading of informal settlements in East London in South Africa
(2020) Tindleni, Nomampondo Thembekile Martha
The demand for adequate and affordable housing continues to grow unabated globally and South Africa is no exception. Currently, the global housing backlog is estimated to be at about 330 million households. The figure is forecasted to increase by more than 30% by 2025. This means than about 440 million households, or 1.6 billion people won’t have access to decent housing. In South Africa, the mushrooming of informal settlements reflects on the inability of the state to respond to the complex issues surrounding access to housing. While the government has attempted to address this situation through policies, it was only until recent that it took a positive approach to dealing with informal settlements. Through the comprehensive plan on human settlements, attention is paid on improving the lives of informal settlement dwellers with an emphasis on in situ upgrading process. Ironically, despite the allocation of a grant to upgrade informal settlements in Duncan Village under the Urban Settlements Development Grant (USDG) for bulk services to the metropolitan municipality and Human Settlements Development Grant (HSDG) for top structures and social amenities, no remarkable improvements have been witnessed in this respect. The grant has since been returned to the Treasury while conditions on the ground do not reflect any positive change towards upgrading of informal settlements. This study therefore draws from these developments and investigated the underlying contestations surrounding the failure to upgrade informal settlements in Duncan Village. Information for this study was gathered through qualitative research methodology where both primary and secondary sources of data were employed. Unstructured face to face interviews shall were conducted with key informants (those with relevant information on the subject under study). Complementary information was gathered through observations and document analysis where documents such as housing policies and relevant literature were reviewed. The research unravelled that while the South African government seek to upgrade informal settlements through policies such as the ISUP, there is a mismatch between policy intentions and what transpires on the ground. One of the major themes coming out from this study is that officials who are tasked with foreseeing the upgrading of informal settlements are incompetent. The study further observed that failure to upgrade informal settlements in East London Duncan Village can mainly be attributed to power struggles that exist between the national and local governance. It is within these power dynamics that there is not enough engagement with local people when it comes to developing and implementing policies such as the ones on informal settlement upgrading. The study therefore recommends the need to align different government departments in order to tap in skills and expertise from relevant officials. There is also need to draw lessons from countries that successfully implemented projects on upgrading of informal settlements.
Local responses to the unified metropolitan transport authority in Kochi, India:
(2019) Reeves, Sarah Elizabeth
This research interrogates the meaning, genealogy and local interpretations of the proposed Unified Metropolitan Transport Authority in Kochi, India. The methodological approach is key in exploring the complex environment in which this policy is situated. The centrality of relationships and narratives in this research meant that rich interactions with local actors and an evaluation of my own positionality as an ‘outsider’ guided the research process. Three core thematic areas revealed three distinct findings. The first is that policy genealogy at the local level is produced both through its history and through dynamic alliances between stakeholders of varying power. The perception of power in choosing to form policy networks alters the meaning of the policy in discourse and as a document. The second finding is that ideas travel from international ‘spaces’ to local ‘places’ through global, hegemonic circuits. Ideas from the Global North are easily able to land in the Global South and in turn shape the perceptions and decisions of local actors in Kochi. The third finding is that there are discrepancies between the rhetoric of policy in the form of meta-narratives and the way policy is enacted in practice. Stakeholders agree on the underlying promises that allow UMTA to gain traction but the agency and discretion of individuals means that policy practice is highly diverse. This process reveals contestations and negotiations for power at the local scale promulgating in changing forms of governance in Kochi. It can be stated that something unique is happening in Kochi which is illustrated in its dynamic policy landscape.
Prediction of Blast Vibrations from Quarries using Machine Learning Algorithms and Empirical Formulae
(2019) Morena, Badisheng Isaac
The aim of this study was to, firstly, use machine learning algorithms to predict Peak Particle Velocity (PPV) in order to optimise blasting layouts and reduce the risk of damaging surface structures. Empirical models developed by the United States Bureau of Mines (USBM) (1963) and Ambraseys and Hendron (1968) were compared to the machine learning algorithms. The tests conducted were interpolation and extrapolation. Most of the data used in this report was obtained from the USBM’s Bulletin 656. The data was analysed using a qualitative and quantitative research methods. The Cubist machine learning model (Kuhn, 2018) performed the best in the interpolation test with a coefficient of determination (R2) of 83.39 % and a root mean squared error (RMSE) and mean absolute error (MAE) of 10.64 and 7.30 respectively. The empirical models performed the best with the extrapolation test with an average R2 of 88 % and RMSE and MAE of 9.17 and 6.59 respectively. This research has shown the effectiveness of machine algorithms in predicting PPV and empirical formulae using historical data from different sites. However, explosive and geotechnical information was not available in the dataset and it is therefore recommended that further research be conducted with this data.
Stagnation heat transfer on a concave surface cooled by unconfined slot jet
(2015) Aziz, Maurel Nguepnang
Heat transfer at the stagnation point on a concave surface and on a flat plate subjected to un-confined slot jet impingement is characterized and compared at a fixed jet Reynolds number of ReB = 20000. The concave surface diameter-to-slot width ratio is fixed at 9.0 whilst the slot exit-to-target surface distance, H/B, varies from 0.5 to 20.0. In particular, the non-monotonic variation of heat transfer at the stagnation point with H/B is fluidically explained. The present results clarify that the deflection zone formed on the target surface as a result of the jet impingement leads to the upstream shift of the peak in turbulence strength that exactly coincides with the peak of heat transfer at the stagnation point. With the concave surface, the impinging jet deflected radially on the surface is re-entrained into the incoming jet due to the curvature, which causes the shortening of the potential core of the slot jet and the longitudinal upstream shift of the peak in turbulence strength compared to the flat plate. Therefore, the peak in heat transfer at the stagnation point occurs at shorter H/B on the concave surface than on the flat plate.
The industrial viability and characterization of WC-Co alloys produced by acid leaching and recycling techniques
(2016) Freemantle, Christopher Stuart
In the current study, the well-established zinc recycling process and a prototype acetic acid recycling plant were successfully employed to recycle cemented tungsten carbide scrap material for re-use as production powders. The recycled materials were studied and compared to new materials at each stage along the cemented carbide manufacturing route, in a production environment. Analysis of by-product materials from the zinc recycling process revealed that while some by-product material can be readily converted into powder using the supplementary acetic acid method, the rest is most efficiently recovered by using a second zinc recycling run and by controlling the size and purity of the scrap material introduced into the process. Various analytical techniques, including the novel use of proton induced x-ray emission studies were used to characterize the materials in both the powder and sintered form. The analyses revealed that the recycled materials possessed superior microstructural homogeneity than new materials, and greater than 99% purity. Studies of milling behavior and slurry rheology revealed no adverse effects of using recycled materials, provided that the slurry properties prior to powder spray drying were appropriately controlled. Polymer binder integrity remained intact despite the longer milling times associated with the use of recycled materials, and the superior slurry stability of recycled materials was demonstrated. The flow behavior and powder rheology of the spray dried powders was found to depend on the precursor slurry rheology and particle grain size. This was controlled predominantly by the formation of a sufficient yield stress to produce ideal, dense granules for greater ease of manufacturing, in both new and recycled powders. The acetic acid recycling technique can be used as a complimentary recycling process to the existing zinc recycling process, and can produce useable recycled material at low cost.
Urban continuity :the urban regeneration of Fordsburg through integrating the mall (the Oriental Plaza) and the grid (urban fabric)
(2020) Da Silva, Paulo
This research explores urban continuity in a part of Johannesburg. The objective is to broadly investigate the history of Fordsburg, its role as a mixed use precinct and to address the issues caused by 1970s imposed Modernism. Cities reveal the relationship between the individual and the greater whole. They bring people together for the mutual benefit and support of each other. This demonstrates the co-existence of different layers of history and embodies a level of continuity - this is the first reference to the title of this research. Continuity does not signify a linear one after the other system, but rather it is an interpretation of time and of physical space, in which the past continues to exist in the present. Michael Focault (1980), an historian and philosopher, states: “space is history.” We all have relationships with the city that rely on the physical formation of the city and its civic history to determine our identities. It is a complex process that is best understood through urban morphology. Oliveira et al (2015) states that there is more to urban morphology that also reveals the elements of a city. These elements form typologies which have genealogies (Dovey et al, 2016). Continuity also applies to the urban patterns produced in cities, which are revealed from examining the physical environment (Alexander et al, 1977). The physical environment, which is an element of urban morphology, focuses on the act of habitation and spatial principles (von Meiss, 2015). It is an appropriate subject because it forms the basis for urbanity and the background atmosphere for living in possible happiness and comfourt. The physical urban environment has codes and conventions that need to be learned, understood and challenged. Fordsburg, a metropolitan suburb in Johannesburg which embodies decades of history and functions within two extremes of Johannesburg’s physical environment: it possesses some of the best qualities of urbanity and also some of the poorest. The site of these urban extremes is the Oriental Plaza: which is a modernist suburban mall masquerading as an urban market. To the west of the mall exists a bastion of urbanity and to the east of the mall is an environment that has become desolate and lost. Auge (1995) and Trancik (1986) describe poor urban spaces as anti-space or lost space, that doesn’t not provide any real benefit for urban living. The challenge is therefore to understand how to connect the eastern and western urban fabric, regenerate the lost urban spaces and stitch urban typologies together meaningfully. The principles of urban continuity (Dewar et al, 1992) offer an appropriate design tool to promote positive change. The principles of urban continuity also offer to the opportunity to realize the mall as a permeable catalyst for Fordsburg’s connection to Johannesburg’s eastern fringe
Vuk’ uphande!: re-imagining a new multi-skilled trading space in the township of Bekkersdal to economically and socially uplift informal businesses.
(2022) Mawelela, Anele
‘Vuk’ uphande!’ a South African slang word that means ‘wake up and hustle’, commonly used by those that identify as hustlers. Informal traders are an expression of this term as they are individuals that trade in the streets for survival means. This research report intends to study the issue of informal businesses and use the positive socio-economic aspects of such businesses in the township of Bekkersdal, west region of Gauteng, South Africa, by creating appropriate infrastructure and allow for skills development that will help uplift and enhance the community’s growth. In South Africa, informal businesses play a signifi cant role in creating jobs (Stats SA reported 754,000 jobs gained through informal employment) and ensuring that those who are less privileged in society are able to generate income. Through their engagement in business in the informal sector, they are able to survive and strive when a country is facing economic recession. According to Survey of Employers and Self-Employed (SESE), it estimated about 70% population of people is employed in the informal sector due to lack of formal employment. The research will be conducted through interviews, mapping and literature reviews by analysing and studying of good-trading value chains that is knowledgeable by small scale traders in Bekkersdal township. The expected outcomes of this study is to bring forth an architectural proposal that will help uplift and enhance the existing trading activities and as well present new functions of skills development and learning to support a greater context of Bekkersdal informal traders.

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Browsing 3. Electronic Theses and Dissertations (ETDs) - All submissions by Faculty "Engineering and the Built Environment"

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