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Optical surface quality and molecular dynamics modelling of ultra-high precision optical silicon machining

  • Authors: Abdulkadir, Lukman Niyi
  • Date: 2019-04
  • Subjects: Engineering design -- Data processing , Manufacturing processes -- Data processing , Mechatronics
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/66552 , vital:75601
  • Description: Hard and brittle materials, such as silicon, silicon carbide etc., are widely used in aerospace, integrated circuit, and other fields due to their excellent physical and chemical properties. However, these materials display poor machinability owing to hardness, brittleness, non-linearity in machining process and complexities in selecting suitable machining parameters and tool geometry. These leads to low quality lenses due to subsurface damage and surface micro-crack. Additionally, it is experimentally very difficult to observe all nanoscale physical phenomena due to in-process measurement problems, inaccessible contact area of tool and workpiece, and the difficulty of surface analysis. With the use of molecular dynamics (MD) which is a comprehensive nanoscale modelling technique, proper selection of process parameters, tool geometry and online monitoring techniques, production of freeform optics is possible through Ultra-high precision diamond turning (UHPDT). Though, depending on view point, machinability in UHPDT may be in terms of tool wear rate, hardness, chip morphology, surface roughness, and other benchmarks. These situations have called for more insights, which on the long run will help to achieve high precision manufacturing with predictability, repeatability, productivity and high infrared (IR) optical quality. In this thesis, UHPDT of monocrystalline silicon at atomistic scale was conducted to investigate combined effects of edge radius, feed rate, cutting speed, depth of cut, rake and clearance angles hitherto not done so far. Using appropriate potential functions with the MD algorithm, comprehensive analysis of thermal effects, diamond tool wear, phase change, cutting forces and machining stresses (normal, shear, hydrostatic and von Mises) were carried out. Dislocation extraction algorithm (DXA) and radial distribution function (RDF) were used to evaluate dislocation nucleation, variations in bond lengths, microstructural transformation and represents structural changes in histogram form. Selected parameters for optical quality surface roughness were afterwards compared and optimized through response surface methodology (RSM) based on Box Behnken (BBD) and Taguchi L9 methods. The results indicated that, silicon atoms in the chip formation zone undergo high pressure phase transformation (HPPT) at high hydrostatic pressure and temperature.Silicon microstructure transformed from four-coordinated diamond cubic structure (Si- I) to unstable six-coordinated body-centered tetragonal structure (β-silicon) which then transformed to amorphous silicon atoms (a-Si) through amorphization. These resulted in plastic deformation and defects in the machining zone causing subsurface damage. Stress analysis indicated that the compressive stress in the machining zone (i.e. amorphous region) suppressed crack formation contributing to continuous plastic flow which is responsible for silicon ductile-mode cutting. Furthermore, formation of silicon carbide which constituted diamond wear was observed to be by sp3 - sp2 diamond carbon atom disorder and tribochemistry. The tribochemistry occurred through both multiphase and solid-state single-phase reaction between diamond tool and silicon workpiece at cutting temperatures above and below 959 K. Both the experimental findings and the simulation results reveal that, at edge radius less than uncut chip thickness, tool wear was more of rake wear than flank wear. Tool wear and kinetic friction reduced as the edge radius approached the uncut chip thickness while forces, stresses and SCE increased. When machining silicon at differentratio, silicon stress state, SCE, SSD, forces (reduced with increase in clearance angle), shear plane, chip velocity and chip ratio increased as edge radius and rake angle increased, while, kinetic friction, chip length and thickness reduced. The crystal lattice of the machined surfaces and subsurface deformed layer depth increased with increase in edge radius, feed and rake angle. Amongst all tested and analysed parameters, feed rate had the highest influence on surface quality while depth of cut showed the least. Acoustic emission was also monitored during machining and its results statistically analysed. The trends of the monitored acoustic emissions showed its capability to adequately represent and predict surface roughness results. Based on the developed simulation model a novel method for quantitative assessment of tool wear was proposed. The proposed model can be used to compare tool wear using graphitization and tribochemistry to decide the path and mode of the diamond tool wear. Finally, based on the experiment results and predictive model, a novel combination and hierarchical arrangement of the considered factors capable of suppressing tool wear and improve attainable machined surface roughness when turning hard-to-machine materials was proposed. , Thesis (D.Phil) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 2019
  • Full Text:
  • Date Issued: 2019-04

Optical surface quality and molecular dynamics modelling of ultra-high precision optical silicon machining

  • Authors: Abdulkadir, Lukman Niyi
  • Date: 2019-04
  • Subjects: Lasers -- Industrial applications , Manufacturing processes , Materials science
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/66551 , vital:75600
  • Description: Hard and brittle materials, such as silicon, silicon carbide etc., are widely used in aerospace, integrated circuit, and other fields due to their excellent physical and chemical properties. However, these materials display poor machinability owing to hardness, brittleness, non-linearity in machining process and complexities in selecting suitable machining parameters and tool geometry. These leads to low quality lenses due to subsurface damage and surface micro-crack. Additionally, it is experimentally very difficult to observe all nanoscale physical phenomena due to in-process measurement problems, inaccessible contact area of tool and workpiece, and the difficulty of surface analysis. With the use of molecular dynamics (MD) which is a comprehensive nanoscale modelling technique, proper selection of process parameters, tool geometry and online monitoring techniques, production of freeform optics is possible through Ultra-high precision diamond turning (UHPDT). Though, depending on view point, machinability in UHPDT may be in terms of tool wear rate, hardness, chip morphology, surface roughness, and other benchmarks. These situations have called for more insights, which on the long run will help to achieve high precision manufacturing with predictability, repeatability, productivity and high infrared (IR) optical quality. In this thesis, UHPDT of monocrystalline silicon at atomistic scale was conducted to investigate combined effects of edge radius, feed rate, cutting speed, depth of cut, rake and clearance angles hitherto not done so far. Using appropriate potential functions with the MD algorithm, comprehensive analysis of thermal effects, diamond tool wear, phase change, cutting forces and machining stresses (normal, shear, hydrostatic and von Mises) were carried out. Dislocation extraction algorithm (DXA) and radial distribution function (RDF) were used to evaluate dislocation nucleation, variations in bond lengths, microstructural transformation and represents structural changes in histogram form. Selected parameters for optical quality surface roughness were afterwards compared and optimized through response surface methodology (RSM) based on Box Behnken (BBD) and Taguchi L9 methods. The results indicated that, silicon atoms in the chip formation zone undergo high pressure phase transformation (HPPT) at high hydrostatic pressure and temperature Silicon microstructure transformed from four-coordinated diamond cubic structure (Si-I) to unstable six-coordinated body-centered tetragonal structure (β-silicon) which then transformed to amorphous silicon atoms (a-Si) through amorphization. These resulted in plastic deformation and defects in the machining zone causing subsurface damage. Stress analysis indicated that the compressive stress in the machining zone (i.e.amorphous region) suppressed crack formation contributing to continuous plastic flow which is responsible for silicon ductile-mode cutting. Furthermore, formation of silicon carbide which constituted diamond wear was observed to be by sp3 - sp2 diamond carbon atom disorder and tribochemistry. The tribochemistry occurred through both multiphase and solid-state single-phase reaction between diamond tool and silicon workpiece at cutting temperatures above and below 959 K. Both the experimental findings and the simulation results reveal that, at edge radius less than uncut chip thickness, tool wear was more of rake wear than flank wear. Tool wear and kinetic friction reduced as the edge radius approached the uncut chip thickness while forces, stresses and SCE increased. When machining silicon at different ratio, silicon stress state, SCE, SSD, forces (reduced with increase in clearance angle), shear plane, chip velocity and chip ratio increased as edge radius and rake angle increased, while, kinetic friction, chip length and thickness reduced. The crystal lattice of the machined surfaces and subsurface deformed layer depth increased with increase in edge radius, feed and rake angle. Amongst all tested and analysed parameters, feed rate had the highest influence on surface quality while depth of cut showed the least. Acoustic emission was also monitored during machining and its results statistically analysed. The trends of the monitored acoustic emissions showed its capability to adequately represent and predict surface roughness results. Based on the developed simulation model a novel method for quantitative assessment of tool wear was proposed. The proposed model can be used to compare tool wear using graphitization and tribochemistry to decide the path and mode of the diamond tool wear. Finally, based on the experiment results and predictive model, a novel combination and hierarchical arrangement of the considered factors capable of suppressing tool wear and improve attainable machined surface roughness when turning hard-to-machine materials was proposed. , Thesis (PhD) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 2019
  • Full Text:
  • Date Issued: 2019-04

The Impact of Energy Consumption on The Profitability and Renewable Energy Preference among SMEs in The KSD Municipality

  • Authors: Vikela, Sithole Liso
  • Date: 2019-03
  • Subjects: Energy consumption , Cost effectiveness
  • Language: English
  • Type: Master's/Doctoral theses , text
  • Identifier: http://hdl.handle.net/11260/6730 , vital:47570
  • Description: This study investigated the impact of energy consumption on the profitability and renewable energy preference among SMEs in the King Sabata Dalindyebo (KSD) local municipality. Cross sectional data was collected using a questionnaire and the adoption of information acceleration (IA) technique. The theoretical framework applied in this study is the theory of consumer-fuel-energy choice which is based on the energy ladder model and the associated fuel switching. Short-run sensitivity analysis (SRA), cost-benefit analysis (CBA) and multinomial logit model (MNL) were employed to measure the profitability and switching behaviour of the firms. SRA showed that the average monthly profit/loss by all firm categories were positive indicating a profit in the consumption of non-renewable energy (NRE). In contrast, results showed that all categories of the firms’ ran at loss if they were to switch to the renewable energy (RE) immediately. Results for CBA indicate that only RE system option satisfied the economic viability of all the three CBA decision criteria on both discount rates, proving to be a viable investment choice for all firm categories. The MNL regression results showed that the number of rooms, firm revenue, irregular power experiences, product information, price, business age, firm grades, gender of the respondent, and the educational levels have a statistically significant impact on willingness to switching from substantial to full willingness. The study recommends establishment of financial subsidy to SMEs to enable them switch to RE system. The research also suggests the need for policies and incentives on profit enhancing strategies, symmetric product information and environmental benefits for switching to RE by SMEs in the rural areas. Key words: Energy consumption, Profitability, Willin¬gness to switch, Cost-Benefit analysis, Multinomial logit model. , Thesis (MCom) -- Faculty of Commerce and Administration, 2019
  • Full Text:
  • Date Issued: 2019-03

Part-time Bachelor of Education students’ cognitive shutdown in research methods and statistics in one institution in Eswatini: Towards a framework for epistemological access

  • Authors: Mukarombwa, Percy
  • Date: 2019-02
  • Subjects: Research -- Methodology , Education, Higher -- South Africa , Education -- Research -- Methodology
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10353/21689 , vital:51742
  • Description: The study was on part-time Bachelor of Education students’ cognitive shutdown in Research Methods and Statistics. It had a view to develop a framework for Epistemological Access. The thesis argued that cognitive shutdown and epistemological access in Research Methods and Statistics can be understood better by looking at the ‘knowledge’ and the ‘knower’ and the relationship between these two. Informed by concepts selected from the Threshold Concepts Theory, Legitimation Code Theory and Self-directed Learning Theory, it developed a conceptual framework for making sense of B.Ed. students’ epistemological access challenges, such as cognitive shutdown, inaccessibility and lack of interest in the course. The study was informed by Post-positivism, and the research approach adopted was a mixed method, with a sequential explanatory mixed method research design. Thirty (30) part-time B. Ed. students were the population and the sample as well, meaning all took part in the study. Two lecturers who teach Research Methods and Statistics (RM & S) also constituted the population and sample. The questionnaire and the interview tools were used to collect data. Data from the questionnaire were presented in tables, bar graphs, pie-charts and doughnuts and analyzed in percentages. That from the interview schedule was presented in descriptions and narratives (themes), and analyzed by thematic analysis. The major findings of the study were as follows: Being a part-time student affected performance. Age does not affect the students’ performance in RM & S. Splitting RM & S makes it easier for the students to understand the various concepts. Students enjoyed Statistics more. RM & S is one of the difficult courses. Time was a major factor influencing the performance of the students. Lecturers do not vary their teaching strategies. Mathematics phobia affected the performance of students. Lack of a base in RM & S from previous studies affected students’ performance. Mathematics phobia affected performance. RM & S knowledge typologies comprised the following specialization codes: Everyday knowledge, Content discipline, General academic knowledge and Scientific Literature. There are code matches and code clashes in terms of the course outline and there are more code clashes than matches. Conclusions reached were: The module is very difficult to some students. Most students prefer an examination on each component, that is, RM, & S, separately. Splitting RM & S makes it easier for the students to understand the various concepts. Being a part-time student affected performance in RM & S. Mathematics phobia as well as lack of a base in RM & S from previous studies affected the performance of the students. There are difficult concepts noted by both staff and students as troublesome knowledge. These affected the performance of the students. From the analysis of the RM & S course outline using the LCT, it was further concluded that there are aspects which constitute everyday knowledge, which are content discipline, general academic knowledge and scientific literacy as knowledge typologies. A further analysis of the B.Ed. course outline using the LCT came up with code matches and code clashes, and the RM &S curriculum has more code clashes than code matches. Recommendations were that the module should be split into RM & S and taught separately. Lecturers should device ways to make sure that troublesome concepts do not affect the performance of the learners. Lecturers should vary their teaching methods to cater for all the different types of part-time B. Ed. students. Mechanisms to demystify that Mathematics is a difficult subject should be employed to curb the phobia. Time should be made available for effective delivery of instruction, as lack of such results in students not understanding the discipline. Finally, educators should understand the knowledge typologies making up RM & S curriculum and that the curriculum has both code lashes and code matches. , Thesis (PhD) -- Faculty of Education, 2019
  • Full Text:
  • Date Issued: 2019-02

"A lean-led-evaluation" of infrastructure development improvement programme in South Africa

  • Authors: Monyane, Thabiso Godfrey
  • Date: 2019
  • Subjects: Construction industry -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/44535 , vital:38131
  • Description: A doctoral study was embarked upon with the intentions of addressing cost management problems encountered on Infrastructure Delivery Projects in South Africa. Given that poor cost performance constitute hindrance to the realization of project goals, it is imperative to eliminate it from project delivery. The prevalence of cost overrun in public sector projects is a call to all stakeholders to address cost management issues in the construction industry. The predominance of cost overruns in public sector construction projects in South Africa has been observed. With the decline of the current economic conditions in South Africa, project performance is a great concern that needs attention. In addition, ineffective initiatives to curb the abuse of the procurement processes are directly affecting the outcomes of construction projects, and if these status quo remains, the sector will continue to have a bad image and continued waste of taxpayers’ money will not cease until the public sector remove non-value adding activities in their operations. Study adopted a mixed methods designed that collected both textual and statistical data. Semistructured interviews were undertaken to determine the outcomes of current project management practices in South Africa. In terms of performance of projects, the status quo paints a disconsolate picture. Findings reveal protracted processes, and the use of unqualified and inexperienced contribute to poor performance of public sector projects. Poor performance continues to dominate the construction sector, especially in the public sector. Interviews data were contrasted with evidence from project-related documents. Based on the data, the study produces a vignette of existing cost management frameworks applied to such projects. Encompassing various stages of the project delivery lifecycle, this vignette will enable an identification of the challenges afflicting cost management on projects. Accordingly, this study identified Lean opportunities from existing cost management practices. Such opportunities will enable identification of effective cost management during project delivery. There appears a need for collaborative cost management practices. Lean tools mentioned for improvement include the 5Whys, the big room, target value design, and the integration of design and construction. A collaborative cost management framework was developed through relevant theories to improve the cost management process of public sector projects.
  • Full Text:
  • Date Issued: 2019

#KeepItReal: discursive constructions of authenticity in South African consumer culture

  • Authors: Plüg, Simóne Nikki
  • Date: 2019
  • Subjects: Consumer behavior Consumers' preferences -- South Africa Brand choice -- South Africa Marketing -- South Africa
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/64973 , vital:28641
  • Description: Writers as diverse as Oscar Wilde (1915), Matthew Arnold (1960), Erich Fromm (1997) and a proliferation of contemporary self-help gurus, variously assert that it is preferable for people to focus on “being”, or to value “who you are”, instead of emphasising “having” or the material possessions you have acquired. These discourses assert that individuals content with “being” are happier and more fulfilled than those involved in the constant (and alienating) motion of acquiring material goods as representations of themselves (de Botton, 2004; Fromm, 1997; James, 2007). This thesis provides an in-depth critical exploration of one of these ideal “ways of being”: authenticity. It does not seek to discover what authenticity is in an empirical sense, nor to define what it should be in a normative sense, but to map the cultural work done by changing and often contradictory discourses of personal authenticity. More specifically, this study uses a qualitative research design, social constructionist theoretical framework, and discourse analytic method to critically discuss the discursive constructions of subject authenticity in South African brand culture. The sample consisted of (1.) ten marketing campaigns of several large, mainstream brands, which were popular in South Africa from 2015 to 2017, and (2.) fifteen smaller South African “craft” brands popular in the “artisanal” context. The analysis is presented in two distinct, but interrelated, sections (namely, Selling Stories and Crafting Authenticity), where the relevant discourses of authenticity for each data set are explored in depth. Through this analysis the thesis provides a critical discussion of the ways in which these discourses of authenticity work to produce and maintain, (or challenge and subvert), subject positions, ideologies, and power relations that structure contemporary South African society.
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  • Date Issued: 2019

'Hayi, they don’t know Xhosa’: Comparative isiXhosa teaching challenges in the Eastern Cape and Gauteng

  • Authors: Kaschula, Russell H , Kretzer, Michael M
  • Date: 2019
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/${Handle} , vital:42499 , https://doi.org/10.1080/02572117.2019.1672318
  • Description: Language-in-education policy in South Africa is underpinned by the Constitution. The gap that this research addresses is the inconsistency of policy implementation and the actual teaching of isiXhosa in primary schools. It analyses the official and overt language policy and the (covert) language practices at schools. Semi-structured interviews were conducted with language teachers and principals. Data were also gathered from classroom observations and document analysis in the Eastern Cape and Gauteng. On the one hand, there are standard language policy documents that exist. These advocate for English as a language of learning and teaching and isiXhosa as a subject. On the other hand, the daily reality in classrooms partly reflects this policy implementation.
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  • Date Issued: 2019

'We throw away our books': Students’ reading practices and identities

  • Authors: O'Shea, Cathy , McKenna, Sioux , Thomson, Carol I
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/187128 , vital:44570 , xlink:href="https://doi.org/10.1016/j.linged.2018.11.001"
  • Description: The aim of this research was to understand university students’ self-reported reading practices. The students attended the University of Fort Hare in South Africa, a historically black institution in a rural and under-resourced setting. A framework of New Literacy Studies (NLS) was used to understand students’ self-reported reading practices and the links between these and their identities. Tools provided by Gee, 2005, Gee, 2011 were applied to conduct a CDA of focus group discussions. In the ‘We Blacks’ Discourse, interviewees ‘othered’ the idea of reading as not being culturally valued. It was closely allied to the ‘Resistance to Reading’ Discourse, as participants explained that they tended to disregard books and did not enjoy leisure reading. The ‘Better Than Us’ discourse was drawn upon to suggest that reading was associated with attitudes of superiority. These discourses tended to homogenise class and other differences between black students and indicated the ways in which their experiences made adopting academic identities difficult. The analysis suggests that the racism of the past continues to impact students’ reading identities. The article concludes that the effects of these and related discourses require a response across the education sector, and transformative pedagogies might be needed in higher education.
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  • Date Issued: 2019

(Latent) Potentials to Incorporate and Improve Environmental Knowledge Using African Languages in Agriculture Lessons in Malawi:

  • Authors: Kretzer, Michael M , Kaschula, Russell H
  • Date: 2019
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/174717 , vital:42503 , ISBN 978-3-030-32897-9 , https://doi.org/10.1007/978-3-030-32898-6_23
  • Description: In their official language policy, nearly all Sub-Saharan African states use their indigenous language(s) as Language of Learning and Teaching (LoLT) only at the beginning of primary schools. This is also the case in Malawi. The curricula in the various school subjects are also highly dominated by ‘Western’ ideas and include very little Indigenous Knowledge (IK). Nevertheless, indigenous languages are frequently used during lessons. This research focused on answering the following questions: How is a meaningful Science Education for pupils in Malawi possible? Does the inclusion of IK and teaching through African Languages assist pupils in any way? Research was done in the Northern Region of Malawi. To obtain a better understanding, semi-structured interviews and ethnographic observations were conducted. The main focus of these interviews was on the subject of ‘Agriculture’.
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  • Date Issued: 2019

(Re) activated heritage:

  • Authors: Siegert, Nadine
  • Date: 2019
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/146321 , vital:38515 , ISBN 9780429624353
  • Description: Book abstract. Securing Urban Heritage considers the impact of securitization on access to urban heritage sites. Demonstrating that symbolic spaces such as these have increasingly become the location of choice for the practice and performance of contemporary politics in the last decade, the book shows how this has led to the securitization of urban public space. Highlighting specific changes that have been made, such as the installation of closed-circuit television or the limitation of access to certain streets, plazas and buildings, the book analyses the impact of different approaches to securitization.
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  • Date Issued: 2019

31° South: the physiology of adaptation to arid conditions in a passerine bird.

  • Authors: Ribeiro, Ângela M , Puetz, Lara , Pattinson, Nicholas B , Dalén, Love , Deng, Yuan , Zhang, Guojie , da Fonseca, Rute R , Smit, Ben , Gilbert, M. Thomas P
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/441508 , vital:73894 , https://doi.org/10.1111/mec.15176
  • Description: Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub‐robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments.
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  • Date Issued: 2019

[Post] Colonial Histories: Trauma, Memory and Reconciliation in the Context of the Angolan Civil War

  • Authors: Baines, Gary F
  • Date: 2019
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/125752 , vital:35814 , https://doi.10.1080/03612759.2019.1587342
  • Description: In 2007, a former South African Defence Force (SADF) paratrooper, Marius van Niekerk, embarked on a journey to confront his shameful memories relating to his role in the Angolan Civil War. From Sweden (where he had gone into exile), Van Niekerk returned to Angola, where he had been deployed during the mid-1980s, and recruited three other veterans of the war to join his party: Patrick Johannes, who had been coerced to fight for the Popular Armed Forces for the Liberation of Angola (FAPLA); Samuel Machado Amaru, who was forcefully enlisted by the National Union for the Total Independence of Angola (UNITA); and Mario Mahonga, who had fought for the Portuguese colonial army before he was recruited by the SADF to fight against the Popular Movement for the Liberation of Angola (MPLA) regime. Van Niekerk had been conscripted at the age of seventeen, and the others had been coerced into their respective militias at more tender ages. It is not clear how the three Angolans were induced to participate in the project, whose objectives they evidently did not share.
  • Full Text:
  • Date Issued: 2019

A "lean-led-evaluation" of infrastructure development improvement programme in South Africa

  • Authors: Monyane, Thabiso Godfrey , Emuze, Fidelis
  • Date: 2019
  • Subjects: Construction industry -- Accounting , Construction industry -- South Africa Project management -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: http://hdl.handle.net/10948/44929 , vital:38189
  • Description: A doctoral study was embarked upon with the intentions of addressing cost management problems encountered on Infrastructure Delivery Projects in South Africa. Given that poor cost performance constitute hindrance to the realization of project goals, it is imperative to eliminate it from project delivery. The prevalence of cost overrun in public sector projects is a call to all stakeholders to address cost management issues in the construction industry. The predominance of cost overruns in public sector construction projects in South Africa has been observed. With the decline of the current economic conditions in South Africa, project performance is a great concern that needs attention. In addition, ineffective initiatives to curb the abuse of the procurement processes are directly affecting the outcomes of construction projects, and if these status quo remains, the sector will continue to have a bad image and continued waste of taxpayers’ money will not cease until the public sector remove non-value adding activities in their operations. Study adopted a mixed methods designed that collected both textual and statistical data. Semistructured interviews were undertaken to determine the outcomes of current project management practices in South Africa. In terms of performance of projects, the status quo paints a disconsolate picture. Findings reveal protracted processes, and the use of unqualified and inexperienced contribute to poor performance of public sector projects. Poor performance continues to dominate the construction sector, especially in the public sector. Interviews data were contrasted with evidence from project-related documents. Based on the data, the study produces a vignette of existing cost management frameworks applied to such projects. Encompassing various stages of the project delivery lifecycle, this vignette will enable an identification of the challenges afflicting cost management on projects. Accordingly, this study identified Lean opportunities from existing cost management practices. Such opportunities will enable identification of effective cost management during project delivery. There appears a need for collaborative cost management practices. Lean tools mentioned for improvement include the 5Whys, the big room, target value design, and the integration of design and construction. A collaborative cost management framework was developed through relevant theories to improve the cost management process of public sector projects.
  • Full Text:
  • Date Issued: 2019

A 3, 5-DistyrylBODIPY Dye Functionalized with Boronic Acid Groups for Direct Electrochemical Glucose Sensing

  • Authors: Ndebele, Nobuhle , Mack, John , Nyokong, Tebello
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/187556 , vital:44671 , xlink:href="https://doi.org/10.1002/elan.201800651"
  • Description: The synthesis and characterization of a novel BODIPY dye functionalized with bis-boronic acid groups to enable direct glucose sensing through selective recognition of carbohydrates is reported. Styrylation with boronic acid groups at the 3,5-positions of the BODIPY core results in an extension of the π-conjugation system of the dye and in a red-shift of the main absorption band from 500 to 637 nm. The functionalized BODIPY dye was adsorbed on a glassy carbon electrode using the drop and dry method. Modified and bare electrodes were characterized using cyclic voltammetry and scanning electrochemical microscopy, while glucose detection was carried out by using differential pulse voltammetry and chronoamperometry. The detection limit was determined to be 1.42 μM. The dye was found to be selective and sensitive towards glucose, since likely interferences have only minor effects on the glucose detection.
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  • Date Issued: 2019

A bargain that dissolves into a poem unwritten: a critique of bargain retail practices and homemaking through critical design

  • Authors: Hawley, Ami Jessica
  • Date: 2019
  • Subjects: Stores, Retail -- Designs and plans -- South Africa , Interior decoration -- South Africa House furnishings -- South Africa -- 20th century Furniture -- South Africa Store decoration Interior architecture
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: http://hdl.handle.net/10948/40349 , vital:36146
  • Description: Although bargains commonly manifest as loud advertisements and trivial objects, as a moment of exchange they provide a basis to critique economic relations and judgements of taste. This research presents a document study of “bargains” in the context of bargain retail practices and homemaking, illustrated in the case of OK Furniture in South Africa; further situated by Julier’s study of economy and class within design culture, and Bourdieu’s fields of cultural production. The investigation builds to a discussion of the research practice, alluded to in the research project’s title, “A bargain that dissolves into a poem unwritten”. The title is an entry from this practice’s journal that conveys how the everyday experience of a bargain might find a connection to poetry when its exchange is seen as a performance; as a moment or encounter “unwritten”, capable of generating different modes of meaning and sociability. Using critical design strategies, the research practice explores the manifesting discountproduct cultures and retail practices associated with homes as a way to inhabit richer interpersonal relationships and unscripted sociability. This is discussed through four critical design proposals and 26 thought experiments, resulting in Text me when you see this, an online concept store that sells bargains, personal agreements, quality time, conversation and curio: www.textmewhenyouseethis.com. The research explores the limits to a bargain’s economic and emotional exchange by asking What if a bargain represented other forms of sociability, and How else might this mode of exchange look? These questions are used in the critique to model critical design towards both poetic expression and pragmatic embodiment of criticality in the project of reflecting on everyday life and what it might “dissolve into”.
  • Full Text:
  • Date Issued: 2019

A blended learning toolkit that accommodates multiple learning styles

  • Authors: Mills, Steven Christopher
  • Date: 2019
  • Subjects: Blended learning , Learning strategies Learning
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10948/30452 , vital:30945
  • Description: The purpose of this study was to identify how blended learning can be designed and incorporated to accommodate multiple learning styles within modules in the Department of Computing Sciences. A design theory was created through an analysis of literature and exploration into the backgrounds of students and lecturers within the Department of Computing Sciences. The design theory is: Blended learning can be a useful approach to accommodate multiple learning styles. Guidelines, and by extension a toolkit, facilitate the development of blended learning and provide effective tools to enable lecturers to successfully incorporate blended learning into their modules. Design-Based Research (DBR) was followed in this study, using a mixed-methods and iterative approach to determine the accuracy of the design theory. For the first iteration, the toolkit was implemented in two modules within the Department of Computing Sciences and for the second iteration, four modules. DBR produces a theoretical contribution and a practical artefact. The most important theoretical contributions are the design theory and guidelines for incorporating blended learning that accommodates multiple learning styles. The practical artefacts are the toolkit and tools therein. The toolkit, which was accessed via a website, guides lecturers through the process of incorporating blended learning that accommodates multiple learning styles and provides them with the necessary tools to do so. The design theory was proven in the evaluation that used a questionnaire to understand the lecturers’ experiences regarding the toolkit and the design theory. Therefore, the guidelines for applying blended learning is a useful approach to address multiple learning styles.
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  • Date Issued: 2019

A case for the adoption of Swahili as a language of early school literacy instruction in Ekegusii-speaking areas of western Kenya:

  • Authors: Mose, Peter , Kaschula, Russell H
  • Date: 2019
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/174645 , vital:42497 , https://www.njas.fi/njas/article/view/433
  • Description: Swahili, a national and official language in Kenya, is in wide use in the country as an inter-ethnic medium of communication and, generally, as a lingua franca. The operative language policy for lower primary–up to grade three–provides for the use of languages of the catchment as languages of instruction. The languages of the catchment refer to the more than 42 indigenous languages spoken in the country. The purpose of this study was to determine and discuss institutional and extra-institutional factors that might favour adoption of Swahili as the best medium–in the current sociolinguistic realities–in the ‘language-of-the-catchment-based’ literacy learning in Ekegusii-speaking areas of western Kenya. Data were obtained through classroom observations, teacher and church leaders’ interviews, observation and analysis of language trends at church worship services, and critical literature review.
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  • Date Issued: 2019

A case study of role conflict experienced by change champions during organisational change

  • Authors: Nakani-Mapoma, Xoliswa Faith
  • Date: 2019
  • Subjects: Organization change , Organization change -- Management , Role conflict , Organizational behavior -- Case studies , Corporate culture -- Case studies
  • Language: English
  • Type: text , Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/96848 , vital:31337
  • Description: A change champion has been defined as a person from any level of the organisation who is skilled at initiating, facilitating and implementing change, and who can effectively champion organisational changes. From a review of the literature, it was anticipated that change champions may experience role conflict, due to the multiple roles that they needed to fulfil simultaneously. Informed by organisational role theory, this research investigated the change management programme of a specific public entity as a case study, and analysed the nature of the role conflict that change champions experienced during a specific organisational change. Semi-structured interviews were conducted with four change champions, the change coordinator and the Executive Director Corporate Services. The organisational documents that relate to change management were also consulted with a view to providing background information and an overview of the change management programme. A deductive thematic analysis approach was used to analyse the data. A coding framework was developed prior to the collection of data, and was used for the identification of theoretical codes and themes in the data. The following codes were developed and explored as types of role conflict: role ambiguity, person role conflict, role strain, role overload and role incompatibility. In terms of the findings, this study confirmed that change champions did experience role conflict during organisational change, mainly due to various expectations that come from different role senders. In the light of these findings, it was recommended that senior managers could reduce the incidents of role conflict by training change champions, introducing an orientation programme for new change champions, consider their personal values when appointing them, and allocating sufficient time for change champions to fulfil this additional role. This study has contributed to the body of knowledge by drawing on role theory and applying it to change management, in order to provide insight on the role of change champions during the organisational change, and in particular the role conflict that they experienced.
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  • Date Issued: 2019

A case-series evaluation of the impact and processes of a service-learning programme on and for caregivers and their children with neurodevelopmental disabilities

  • Authors: Cooke, Nicole
  • Date: 2019
  • Subjects: Developmentally disabled children -- Care , Caregivers -- Training of , Service learning -- Case studies
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/96691 , vital:31309
  • Description: This thesis presents a series of three case studies from data collected as part of a research project exploring the process and impact of a service-learning programme with caregivers and their children with neurodevelopmental disabilities. Following a descriptive case series design, both quantitative and qualitative data are presented to create a comprehensive and rich understanding of each case. In particular, the data tracks change processes in the subjective well-being of the caregiver, the quality of the caregiver-child relationship and the functional development of the child over a twenty-one-week period of receiving public health services and an eight-week period of adding the service-learning programme. The paper also presents qualitative data on the caregivers’ perceptions of and experiences of the public services and the servicelearning programme that the caregivers and their children received. The findings provide important insight into the caregivers’ perceptions of giving and receiving care, with the caregivers’ experiencing significant levels of distress and prominent barriers to accessing healthcare that were seemingly eased with the addition of the service-learning programme. The findings also point to a notable disparity between the quantitative findings and the qualitative interviews with questions being raised about the research being viewed as an intervention in itself.
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  • Date Issued: 2019

A Century of South African Theatre

  • Authors: Krueger, Anton
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/229623 , vital:49694 , xlink:href="https://doi.org/10.1080/10137548.2020.1716515"
  • Description: In many ways, this is an updated repackaging of Loren Kruger's seminal work of 20 years ago, Plays, Pageants and the Drama of South Africa (1999). The material has been extensively revised and reworked using similar categories as the first book, including: pageantry and representations of nationhood, neo-colonial theatre, urbanization and its consequences; the rise of Afrikaans theatre; theatres of resistance; black consciousness; and contemporary theatre. Some of these sections have been extended (such as a longer discussion of HIE Dhlomo) and there is also a completely new section which has not been published elsewhere on current theatre trends (cleverly titled “The Constitution of South African Theatre at the Present Time”).
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  • Date Issued: 2019
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