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

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The affective black experience: struggles with conformity for young black professionals in corporate South Africa
(2017-09) Bokala, Kutlwano Tlamelo
South Africa’s democratic transition was cultured by, amongst others, the mythical ideology of Rainbowism. Rooted in happiness and the promises thereof, the renowned national metaphor was utilised by the state to radically shift the country’s narrative around nationhood towards a shared understanding of identity, belonging, citizenship, and diversity. Today, the influence of Rainbowism within state-led efforts towards social change has slowly deemed under much public scrutiny. Persistent poverty, inequality and violence have fostered the emergence of, what many are calling, an “End of the Rainbow” discourse. As integral and lurid entities within post-apartheid nation-building, black youth and institutionalised spaces have affected and been affected by the shortcomings of Rainbowism. Their shared history and intersecting significance in fuelling collective action amongst South Africans have been well depicted in recent times where youth-led movements have highlighted the inequality and unhappiness that exists in institutions spaces like the university. However, little mention has been made about how black youth are making sense of institutional life within spaces like the workplace, against the backdrop of promised happiness. Through the conversations had with eight young black professionals, this research report centres Rainbowism as a project of happiness that governs institutional life for black youth in South Africa. Happiness is revealed as a dominant discourse operating along axes of power that shape ‘happy’ employees based on various forms of corporeal differentiation.
Drawing on Words: Jasper Johns's Illustrations of Samuel Beckett's Foirades/Fizzles
(1994) Richards, Colin Peter
Between 1973 and 1976 artist Jasper Johns produced some thirty-three illustrations to accompany five prose texts authored by Samuel Beckett. The result was the book Foirades!Fizzles, published in New York in 1976. Almost without exception the critical literature published on this book draws the relation between image and text away from any idea of illustration. And this only when the idea is not simply ignored. This critical attitude reflects a wider tendency in especially elevated critico-aesthetic discourse to consider illustration as aesthetically and textually debased. Bracketed off, illustration merely signals a parasitic relation. Compromising the integrity of the texts it enjoins, it articulates a secondary aesthetic of the accessory. This view seems unproductive not only when applied to Johns's work, but also to image-text combinations more generally. The sheer incidence of such combinations (including illustration) in recent and current aesthetic production suggests that the indifference or prejudicial critical reflex routinely provoked by illustration marks a moment of poverty in contemporary critical thinking. This moment appears solidly rooted in a once dominant and still apparently powerful formalist and purist impulses within modernist discourse. The persistence of these impulses suggests the survival of unexamined, limiting and tenacious critical assumptions. A closer examination of selected texts - pre-modernist, modernist, and post-modernist - point beyond these assumptions. Here the logic of the supplement in particular illuminates very specifically how illustration might come to function, and where its incendiary critical potential may lie. The supplement resists the easy hierarchisation or even synthesis of different texts which has been the fate of illustration. It renders illustration both critically robust and radical. The concept of allegory is also illuminating here. It not only helps us understand better the fate of illustration within modernism and postmodernism, but also provides for enlightening readings of Foirades!Fizzles. In turn, a revaluation of illustration opens up a more productive view of allegory in both modernist and postmodernist discourse. Illustration, in coordinating different semiotic systems, however marginally, can function as a framing, focusing and spacing device, a way of bracketing and specifying themes, structures and forms within a given textual complex, a way of opening readings otherwise foreclosed or overlooked. In this study such readings are articulated through a set of textual configurations which include: vision and perception; the body, eye, and skin; calibration, measurement, and point of view; memory, repetition and originality; and finally liminality, ambiguity and metastable signification. Against the grain of published opinion there is then much to be gained by recognising the capacious critical potential of illustration, what we might term its 'motivated contingency'. Rather than being considered critically inconsequential or an aesthetic impedin1ent, illustration may in fact provide an almost unique opportunity not only to explore issues germane to Johns's work (both independently and in relation to Beckett's texts), but also to address certain important critical debates within postmodern discourse. Its value may be felt in reading Foirades!Fizzles, in reading other image-text combinations, and the broader relations between visual art, literature, and language.
The geology of the Otjosondu manganese area: south west Africa
(1959) Roper, Harold
Geological mapping and compilation of data from mining and prospecting operations in the Otjosondu area in South West Africa provided the information presented in this thesis. The geomorphology of the area is described and the general geology is discussed. Details of the complicated folding suffered by the Iamara rocks are presented. The petrology and petrography of' the outcropping representatives of the ancient sedimentary and intrusive rocks is described under the section on economic geology, interpretations of the complex structures of the ore bodies are presented. The mineralogy of the ores was studied by means of polished sections, X-ray diffraction and differential thermal analysis techniques. It is concluded from both field and laboratory evidence that these ores represent the metamorphosed equivalents of syngenetic manganese bearing sediments
The Morphology and Transport of Mucus in Mammalian Airways.
(1975) Andre William Wessels van As
The mucociliary clearance mechanisms in mammalian pulmonary airways have been re-examined. In this investigation Wistar rats, housed both under specific pathogen free (SPF) and normal animal house conditions, were examined. An intact airway . system from the trachea down to the level of the terminal bronchioles was used. The airway preparation was rapidly isolated and examined under carefully controlled in vitro conditions. Specimens remained viable for at least 10 h. Mucociliary activity was observed through the intact bronchial wall with the aid of incident light. This function could be examined at all levels of the pulmonary tree in the same specimen. In contrast to the previously described presence of a continuous mucous bl~ket, the morphology of mucus in the airways of the rat has been shown to be discontinuous. Mucus is present as discrete particles of varying size. Under the light microscope these particles appeared to fall into three categories: droplets less than 4 μm in diameter; flakes 10-70 μm in diameter; and plaques which are conglomerations of droplets and flakes. Scanning electron microscopy reveals that droplets (i.e. single particles) may be as small as 0,5 μm and that composite particles made up of numerous aggregated droplets may be as small as 5 μm in diameter. Plaques are conglomerations of these particles. In the normal intrapulmonary airways only smaller particles are seen and are transported over the individual metachronal fields. In the larger extralobar airways these particles move together to be transported in well defined streams which may be up to 500 μm wide. These streams may follow a winding course up the trachea and more than one may be in operation at a time. Under conditions of hypersecretion such as occurs with chronic respiratory disease in rats (CRD) the number of particles increase peripherally and plaques may be found in small airways. The transport of mucus is however still intermittent and it never becomes confluent. Acute bronchitis results in wide-spread abnormalities of ciliary activity and mucus transport, which leads to total disorganisation of pulmonary clearance. "Chronic bronchitis" associated with CRD results in more organised abnormalities of mucociliary activity. Cilia may become inactive, reverse the .direction of their effective stroke, beat retrogradely, and exhibit abnormal beat patterns which result in impaired mucus clearance. Squamous metaplastic areas further impede mucus transport. In general mucus transport rates were found to be faster in rats with "chronic bronchitis" than SPF rats, provided that the extent of the damage to the mucous membrane was ( not too great in the "bronchitic" animal. This finding was confirmed by the examination of airway preparations approximately 19 h after the exposure to a charcoal aerosol. While significant amounts of charcoal were retained at the bifurcations of bronchi in SPF rats, most of the charcoal was cleared in "bronchitic rats'.'. The only areas where particles were seen were on bronchitic patches or on whirlpools. The findings of this study indicated that mucus was present in a discontinuous form, and that in both SPF and non-SPF animals no evidence for a mucous blanket was found.
The Morphology and Transport of Mucus in Mammalian Airways.
(1975) Andre William Wessels van As
The mucociliary clearance mechanisms in mammalian pulmonary airways have been re-examined. In this investigation Wistar rats, housed both under specific pathogen system frfroeme (tShPeFt)raacnhdeanodrmowanl taonimthael lheovuelseofcotnhdeititoenrms, inwael rbe roexnacmhiionleeds . wAans uinsetadc. t airway The airway preparation was rapidly isolated and examined under carefully controlled in vitro conditions. Specimens remained viable for at least 10 h. Mucociliary activity was observed through the intact bronchial wall with the aid of incident light. This function could be examined at all levels of the pulmonary tree in the same specimen. In contrast to the previously described presence of a continuous mucous bl�ket, the morphology of mucus in the airways of the rat has been shown to be discontinuous. Mucus is present as discrete particles of varying size. Under the light microscope these particles appeared to fall into three categories: droplets less than 4 µm in diameter; flakes 10-70 µm in diameter; and plaques which are conglomerations of droplets and flakes. Scanning electron microscopy reveals that droplets (i.e. single particles) may be as small as 0,5 µm and that composite particles made up of numerous aggregated droplets may be as small as 5 µm in diameter. Plaques are conglomerations of these particles. In the normal intrapulmonary airways only smaller particles are seen and are transported over the individual metachronal fields. In the larger extralobar airways these particles move together to be transported in well defined streams which may be up to 500 µm wide. These streams may follow a winding course up the trachea and more than one may be in operation at a time. Under conditions of hypersecretion such as occurs with chronic respiratory disease in rats (CRD) the number of particles increase peripherally and plaques may be found in small airways. The transport of mucus is however still intermittent and it never be comes confluent. Acute bronchitis results in wide-spread abnormalities of ciliary activity and mucus transport, which leads to total disorganisation of pulmonary clearance. "Chronic bronchitis" associated with CRD results in more organised abnormalities of mucociliary activity. Cilia may become inactive, reverse the .direction of their effective stroke, beat retrogradely, and exhibit abnormal beat patterns which result in impaired mucus clearance. Squamous metaplastic areas further impede mucus transport. In general mucus transport rates were found to be faster in rats with "chronic bronchitis" than SPF rats, provided that the extent of the damage to the mucous membrane was not too great in the "bronchitic" animal. This finding was confirmed by the examination of airway preparations approximately 19 h after the exposure to a charcoal aerosol. While significant amounts of charcoal were retained at the bifurca tions of bronchi in SPF rats, most of the charcoal was cleared in "bronchitic rats .The only areas where particles were seen were on bronchitic patches or on whirlpools. The findings of this study indicated that mucus was present in a discontinuous form, and that in both SPF and non-SPF animals no evidence for a mucous blanket was found.
The penetration and fracturing mechanisms generated in brittle rock by the impingement of a high velocity jet
(1992) Giltner, Scott George
Extensive studies on the jet penetration process in ductile metal targets have been previously carried out in numerous investigations. As a result, the penetration in ductile targets has been characterized by various theoretical models. However the penetration of brittle materials, particularly rock, has received considerably less attention. The lack of information concerning brittle materials is important as major differences between penetration in ductile and brittle materials have been observed. In most instances the actual penetration in brittle materials is far less than that given by theoretical calculations. This thesis presents an investigation into the high velocity jet penetration of brittle rock. The aim of this work is to describe the dynamic forces transmitted into the rock by the jet and the subsequent response of the rock to these forces. It is shown that existing penetration theories do not adequately describe penetration in rock. Of all the jet and target properties considered in the theories examined, target strength is shown to be the most relevant for predicting penetration depth. Recovery of the actual hole created was achieved by overcoring of the hole. Detailed measurements of the hole profile and fracture zones around the hole are presented. From the recovered samples of the hole, thin and polished sections were obtained for microscopic analysis. Results from the microscopic examination of these specimens are discussed from which temperature and pressure information are derived. In order to provide an adequate description of the penetration process, instrumentation was used to measure the penetration velocity, particle acceleration, and dynamic strain generated in the rock. From the instrumentation the interface pressure, dynamic stress, and dynamic strain generated in the rock are quantified and related to the various fracture zones identified around the hole. The results of these tests indicate that penetration in rock can be separated into three distinct phases. Initially the rock behaves as a hydrodynamic fluid should the interface pressure be very high. However as the interface pressure drops, the strength of the rock becomes evident and the second phase is entered into. The second phase is characterized by rapid changes occurring in the behaviour of the rock. Once the behaviour of the rock has stabilized, the third and final phase of penetration is entered. This final phase is predominantly controlled by the rock strength. As a result of this investigation, a better understanding of the interaction between the rock target and penetrating jet has been established. Additionally the behaviour of rock subjected to very high shock pressure has also been described. This has allowed better insight into the material properties governing the penetration process and the fracturing of rock from purely dynamic stresses.
Making the invisible visible
(2015) Coetzer, Diane
No abstract provided.
Laser shock peening in friction stir welded joints with lack of penetration defects
(2016) Leering, Mitchell Patrick
This experimental work was conducted in order to assess the influence of the application of Laser Shock Peening (LSP) to Friction Stir Welded (FSW) joints. LSP has the ability to potentially recover the reduction in joint mechanical properties that arose due to the presence of a common FSW defect known as Lack of Penetration (LOP). The material used throughout this study was 3 mm thick AA6082-T6 Aluminium. This specific material was selected due to its weldability and common use in the manufacturing of aircraft structures. A 20 mm diameter, spiralled profile shoulder and 5 mm diameter, tapered, three facetted pin was used in the manufacturing of the FSW joints. Experimental assessment and optimisation of the FSW parameters window consisted of the varying the tool rotational speed from 630 to 1600 RPM, at five increments and the feed rate from 200 to 600 mm/min, 200 mm/min intervals. The joints were assessed on the overall quality, microstructure, ductility and static strength. The parameter combinations produced joints with ultimate tensile joint efficiencies which ranged from 48% to 74% that of the base material. The initial study showed that higher welding rates, typically associated with low feed rates, resulted in the highest quality joints. This was attributed to the sufficient thermal softening of the material during welding. The increased welding temperatures improved the joint formation, material flow and mechanical properties. Due to the elevated welding temperatures and material flow, substantial flash formation was observed on all joints manufactured with a welding rate of 5 rev/mm and higher. These results formed the foundation of the multi-objective optimisation in order to determine the most suitable parameters for this welding configuration. The optimisation simulation determined the optimum parameters to be, a tool rotational speed of 1433 RPM, feed rate of 196 mm/min and a welding rate of 7.3 rev/mm. Due to the fixed gearing of the CNC FSW machine the required tool rotational speed could not be achieved, thus, all FSW completed after the optimisation was completed at 1600 RPM, 200 mm/min and 8.00 rev/mm. This parameter combination produced a joint of high structural integrity, high ductility and with no visual sign of internal voids, defects or lack of penetration. The performance of the defect free joint formed the foundation of the characterisation of the influence of intentionally introduced LOP defects. LOP was defined as a pre-initiated crack which formed at the root surface during the fabrication of a FSW joint. Controlled and consistent LOP was introduced into the joints, manufactured with welding parameters of 1600 RPM and 200 mm/min, by offsetting the welding tool in combinations of the normal and lateral directions relative to the joint line. The defects originated at the root surface and extended at various lengths through the thickness of the joints due to the numerous offsets. The defects lengths ranged from a few microns to as much as 954.5 μm. A number of defects affected as much as 43% of the joint thickness. The presence of the defects negatively affected the joints structural static strength by as much as 9% to 27% (dependent on the size of the defect) and dynamic fatigue life of as much as 36%. Laser Shock Peening (LSP) is a novel post manufacturing technique, which has been used to introduce compressive residual stresses within the near surface of the metallic components. A LSP processing was completed without a protective ablative coating (LSPwC), at a wavelength of 1064 nm and pulsed nano-second laser at 10 Hz. The characterisation of varying the laser power intensity and processed coverage to the base of FSW AA6082-T6 Aluminium was completed through extensive parameter window exploration. Factors such as the quality of the energy delivery, sample deflection, strain hardening, penetration of effects through the FSW joint thickness and the improvement of the fatigue life of the base material were used to define the appropriate parameters. A multi-objective optimisation strategy was implemented in the attempt to fully explore the regions between tested parameter combinations; to provide an optimum set of LSP parameters which would be used in combination of the optimum FSW parameters. The simulation predicted two optimum sets of parameters dependent on the desired outcome of either maximising component fatigue or LSP depth of penetration effect. Due to the nature of this research requiring both fatigue and penetration depth, a parameter set was selected based on parameters that would theoretically provide the maximum for both desired outcomes. The optimum power intensity and coverage was specified as 3.33 GW/cm2 and 1067 spots/cm2. The optimum parameters of each process was combined in an attempt to recover the drop in fatigue life of the joints due to the presence of the LOP defect. LSP was capable of altering the near surface residual stress states of approximately 100 MPa tensile to -150 to -200 MPa compressive across the three measurement ranges. It was found that LSP had minimal effect on the fatigue life of the components in the low cycle fatigue due to the applied stress relaxing the introduced stress thus having minimal effect on the life of the joints. LSP was found to increase the fatigue life of the non-defective joints by as much as 68%. LSP showed a life improvement of approximately 20% in a joint which had a defect length of roughly 175μm. After the application of LSP the samples in the low cycle fatigue tended to fail at a closed cycles to failure as the non-defective unpeened samples. Application of a LSP to a FSW was found to shift the fracture position of the flawed components from the region of the defect to that of the Heat Affected Zone (HAZ) on the advancing side of the weld. It is suggested that, the shift in fracture position was due to critical relocation of the tensile stress during LSP into the HAZ on the advancing side. The results did not conclusively show that LSP was capable of recovering the effects of the LOP but was plausible that it could possible. This has been said due to some samples exhibiting an increase and due to the change in location of the fracture position.
A preliminary description of South African Sign Language syntax
(2017) Wright, Donovan
This study is a preliminary investigation into the syntax of South African Sign Language. Utilising narrative data within a case study approach, signing is observed and analysed in terms of Radical Construction Grammar. An emphasis is placed on signs as form-meaning pairings, in which information of form is drawn from previous research on the phonology and morpho-syntax of signed languages. Meaning is explained within the same sphere, drawing on established literature regarding meaning in signed languages – with the addition of Mental Space and Conceptual Blending theories. The aim is to describe the signing elicited as in-depth as possible while covering a broad number of relevant aspects. The efficacy of Radical Construction Grammar as a theoretical framework in signed language is also considered. Results include descriptions of different construction types and a holistic view of signing. Schemas are proposed for common constructions, and Radical Construction Grammar is posited as a viable alternative to a traditional understanding of syntax.
Teachers’ perceptions of school-based support teams in the Johannesburg East School District
(2015) Schneiderman, Farryn
The aim of this research study was to explore how teachers in a sample of primary schools in the Johannesburg East school district of Gauteng perceive the school-based support teams (SBST) at their schools. These support teams are supposed to be existing structures within public schools in South Africa according to the policy outlined in Education White Paper 6 (Department of Education, 2001). Teachers in South African government schools often face considerable challenges in the implementation of inclusive education. These include catering to the individual needs of all learners within classrooms that contain a large number of learners. A mixed-method exploratory descriptive design was used to carry out the exploration of this study. Five government primary schools in the Johannesburg East school district participated in this study and there were fifty-four educators that voluntarily completed a questionnaire that consisted of both open- and closed-ended questions. Data from the questionnaires were analysed by using frequency and descriptive analysis, as well as thematic content analysis. Results from this questionnaire indicated that the majority of the respondents have a positive outlook on the school-based support team approach and would like this approach to continue within their school. They do however require additional support from the district support team and would need assistance from both the district and school-based support teams in order to constructively deal with specific barriers to learning. This will improve the collaborative support and emotional well-being of the educators, thereby improving the quality of education provided to the learners.

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

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