Towards the development of a MIR NOPA for time-domain ptychography

Thesis (MSc)--Stellenbosch University, 2021.ENGLISH ABSTRACT: This thesis discusses a noncollinear optical parametric amplifier as a source of ultrafast mid-infrared light for spectroscopic experiments and aims to provide a consistent method for the generation thereof. The underlining theory and fundamental principles of this device is outlined as well as various experimental considerations. A design for an experimental setup to generate suitable ultrafast mid-infrared light is proposed and preliminary optical devices are implemented. Generation of a 160 nm bandwidth, near-infrared supercontinuum centred at 1067 nm is shown to be inadequate for the generation of mid-infrared pulses. Parasitic second harmonic-, sum frequency and difference frequency generation processes are also shown to impede mid-infrared generation. These restricting experimental phenomena are highlighted and methods to bypass these limits are given. Finally, as a demonstration of usefulness of such a source of infrared pulses, the novel time-domain ptychographic measurement, HIPPY, of a material’s response to mid-infrared light is simulated.AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die gebruik van ‘n nie-kolineêre optiese parametriese versterker as ‘n bron van ultravinnige middelinfrarooi ligpulse en poog om ‘n metode te voor te lê vir die generasie daarvan. The onderliggende teorie en fundamentele beginsels van hierdie optiese toestel word bespreek asook verskeie eksperimentele oorwegings aangaande die ontwerp. ‘n Ontwerp van ‘n optiese toestel vir die generering van ultravinnige middelinfrarooi lig word voorgestel en voorafgaande eksperimentele opstellings is geimplementeer. Die generasie van ‘n supercontinuum pulse by 1067 nm met ‘n bandwydte van 160 fs word getoon om ongepas te wees vir middleinfrarooi pulse generasie. Parasitiese tweede harmoniek-, som frekwensie- en verskil frekwensie generasie prosesse word ook getoon om middelinfrarooi generasie te verhoed. Verskynsels wat hierdie generasie belemmer word uitgelig met voorgestelde metodes om dit te beperk. Laastens, as ‘n demonstrasie van die nut van infrarooi pulse, is ‘n nuwe tyd gebieds tigografiese tegniek, HIPPY, gesimuleerMaster

Black female first-generation students’ lived experiences at an historically white South African university

Thesis (MA)--Stellenbosch University, 2022.ENGLISH SUMMARY: It is public knowledge that the foundation of South African higher education (HE) is primarily laid by colonial and apartheid policies, particularly in historically white institutions (HWI’s). In this research literature, whiteness was used to unearth the historical conduct of HWI’s and exclusion of historically marginalised students. It is within this context that I sought to investigate the lived experiences of Black female first-generation postgraduate students in an HWI to understand perceptions of gendered and racialized microaggressions and/or institutionalized exclusionary practices, strategies employed to negotiate the university system, and expressed support needs. Located within an interpretivist research paradigm, I used a qualitative research method, semi-structured interviews and thematic analysis to examine the lived experiences of three Black students who identify as Black African, female and first-generation. Phenomenology was used as a theoretical lens to interpret findings. Findings revealed the experience of culture shock, vulnerability to gendered racism and pressures of being a first-generation student. Ultimately the tensions of navigating intersected and marginalised social identities at an HWI was elucidated in the findings. As a result of navigating these tensions, participants expressed an impact on their emotional and psychological wellbeing. Despite it all, participants found ways to resist marginalisation by employing coping mechanisms, exercising agency and staying woke. The expressed support needs highlight the need for urgency in transformation and representation of Black African female academics. To conclude, the research suggests a holistic transformation approach that understands the experiences and needs of students with intersecting and marginalised identities. That transcend the idea of diversifying numbers of historically marginalised students as the only form of transformation. Keywords: campus culture; first-generation students; gendered racism; historically white institution; intersectionality of historically marginalised identities; transformation.AFRIKAANS OPSOMMING: Dit is algemene kennis dat die fondasies van hoër onderwys (HO) primêr deur koloniale en apartheidsbeleid gelê is, spesifiek in histories wit instellings (HWI). In hierdie navorsings is die konsep witheid gebruik om die historiese optrede van HWI’s en die uitsluiting van histories gemarginaliseerde student aan die lig te bring. Dit is in hierdie konteks wat ek gepoog het om die geleefde ervarings van Swart vroulike eerste-generasie nagraadse studente aan ‘n HWI te ondersoek, ten einde die volgende te verstaan: persepsies van geslags- en rasgebaseerde mikro-aggressies en/of institusionele uitsluitende praktyke, strategieë wat gebruik word om die universiteitssisteem te navigeer, en uitgesproke ondersteuningsbehoeftes. Binne ‘n interpretivistiese navorsingsparadigma het ek gebruik gemaak van ‘n kwalitatiewe navorsingsmetodiek, semi-gestruktureerde onderhoude, en tematiese analise om die geleefde ervaring van drie Swart studente ondersoek wat identifiseer as Swart Afrikaan, vroulik en eerste-generasie. Fenomenologie is as teoretiese lens gebruik om bevindinge te interpreteer. Bevindings het die volgende aan die lig gebring: ervaring van kultuurskok, weerloosheid ten opsigte van geslagsgerigte rassisme, en die druk daarvan om ‘n eerste-generasie student te wees. Die spanning daarvan om oorvleuelende en gemarginaliseerde sosiale identiteite aan ‘n HWI te navigeer is deur die bevindings toegelig. Een van die gevolge daarvan om hierdie spanningsveld te navigeer, is negatiewe ‘n impak op die emosionele en sielkundige welstand van die deelnemers. Ten spyte daarvan het deelnemers ook maniere gevind om weerstand te bied teen marginalisering. Die uitgesproke ondersteuningsbehoeftes aksentueer die dringendheid vir transformasie en representasie van Swart vroulike akademici. Om saam te vat, die navorsing suggereer ‘n holistiese transformasieproses wat die ervarings en behoeftes van studente met oorvleuelende en gemarginaliseerde identiteite voorop stel. Stellenbosch University https://scholar.sun.ac.Master

Creating 3D models using reconstruction techniques

Thesis (MSc)--Stellenbosch University, 2018.ENGLISH ABSTRACT :Virtual reality models of real world environments have a number of compelling applications, such as preserving the architecture and designs of older buildings. This process can be achieved by using 3D artists to reconstruct the environment, however this is a long and expensive process. Thus, this thesis investigates various techniques and approaches used in 3D reconstruction of environments using a single RGB-D camera and aims to reconstruct the 3D environment to generate a 3D model. This would allow non-technical users to reconstruct environments and use these models in business and simulations, such as selling real-estate, modifying pre-existing structures for renovation and planning. With the recent improvements in virtual reality technology such as the Oculus Rift and HTC Vive, a user can be immersed into virtual reality environments created from real world structures. A system based on Kinect Fusion is implemented to reconstruct an environment and track the motion of the camera within the environment. The system is designed as a series of selfcontained subsystems that allows for each of the subsystems to be modified, expanded upon or easily replaced by alternative methods. The system is made available as an open source C++ project using Nvidia’s CUDA framework to aid reproducibility and provides a platform for future research. The system makes use of the Kinect sensor to capture information about the environment. A coarse-to-fine least squares approach is used to estimate the motion of the camera. In addition, the system employs a frame-to-model approach that uses a view of the estimated reconstruction of the model as the reference frame and the incoming scene data as the target. This minimises the drift with respect to the true trajectory of the camera. The model is built using a volumetric approach, with volumetric information implicitly stored as a truncated signed distance function. The system filters out noise in the raw sensor data by using a bilateral filter. A point cloud is extracted from the volume using an orthogonal ray caster which enables an improved hole-filling approach. This allows the system to extract both the explicit and implicit structure from the volume. The 3D reconstruction is followed by mesh generation based on the point cloud. This is achieved by using an approach related to Delaunay triangulation, the ball-pivot algorithm. The resulting system processes frames at 30Hz, enabling real-time point cloud generation, while the mesh generation occurs offline. This system is initially tested using Blender to generate synthetic data, followed by a series of real world tests. The synthetic data is used to test the presented system’s motion tracking against the ground truth. While the presented system suffers from the effects of drift over long frame sequences, it is shown to be capable of tracking the motion of the camera. This thesis finds that the ball pivot algorithm can generate the edges and faces for synthetic point clouds, however it performs poorly when using the noisy synthetic and real world data sets. Based on the results obtained it is recommended that the obtained point cloud be preprocessed to remove noise before it is provided to the mesh generation algorithm and an alternative mesh generation technique should be employed that is more robust to noise.AFRIKAANSE OPSOMMING : Modelle in virtuele realiteit van werklike omgewings het ’n aantal belangrike toepassings, soos byvoorbeeld die behoud van die argitektuur en ontwerpe van geskiedkundig belangrike geboue. 3D kunstenaars kan ingespan word om omgewings te modelleer, maar dit is ’n lang en duur proses. Hierdie proefskrif ondersoek verskillende tegnieke en benaderings wat gebruik word in die 3D rekonstruksie van omgewings deur gebruik van ’n enkele RGB-D kamera en beoog om die 3D rekonstruksie van die omgewing te omskep in ’n 3D-model. Hierdie sal nie-tegniese gebruikers toelaat om self modelle te skep van omgewings, en om hierdie modelle te gebruik in besigheid toepassings en simulasies, soos byvoorbeeld die verkoop van vaste eiendom, die wysiging van bestaande strukture vir beplanning en opknapping. Met die onlangse tegnologiese verbeteringe in die veld van virtuele realiteit soos, byvoorbeeld, die Oculus Rift en HTC Vive, kan ’n gebruiker geplaas word in ’n virtuele omgewing wat geskep was vanaf strukture in die werklike wˆereld. ’n Stelsel gebaseer op Kinect Fusion word ge¨ımplementeer om ’n omgewing te rekonstrueer en die beweging van die kamera binne die omgewing te volg. Die stelsel is ontwerp as ’n reeks selfstandige modules wat die afsonderlike aanpassing, uitbreiding of vervanging van die modules vergemaklik. Die stelsel word beskikbaar gestel as ’n open source C++ projek met behulp van Nvidia se CUDA raamwerk om reproduseerbaarheid te bevorder en bied ook ’n platform vir toekomstige navorsing. Die stelsel maak gebruik van die Kinect-sensor om inligting oor die omgewing vas te vang. ’n Grof-tot-fyn kleinste kwadraat benadering word gebruik om die beweging van die kamera te skat. Daarbenewens gebruik die stelsel ’n beeld-tot-model benadering wat gebruik maak van die beraamde rekonstruksie van die model as die verwysingsraamwerk en die inkomende toneel data as die teiken. Dit verminder die drywing ten opsigte van die ware trajek van die kamera. Die model word gebou met behulp van ’n volumetriese benadering,met volumetriese inligting wat implisiet gestoor word as ’n verkorte getekende afstandfunksie. Die stelsel filter ruis in die ruwe sensor data uit deur om ’n bilaterale filter te gebruik. ’n Puntwolk word uit die volume onttrek deur ’n ortogonale straalvolger te gebruik wat die vul van gate in die model verbeter. Dit laat die stelsel toe om die eksplisiete en implisiete struktuur van die volume te onttrek. Die 3D-rekonstruksie word gevolg deur maasgenerasie gebaseer op die puntwolk. Dit word behaal deur ’n benadering wat verband hou met Delaunay triangulasie, die bal wentelings algoritme, te gebruik. Die resulterende stelsel verwerk beelde teen 30Hz, wat intydse-puntwolkgenerasie moontlik maak, terwyl die maasgenerering aflyn plassvind. Hierdie stelsel word aanvanklik getoets deur om met Blender sintetiese data te genereer, gevolg deur ’n reeks werklike wˆereldtoetse. Die sintetiese data word gebruik om die stelsel se afgeskatte trajek teenoor die korrekte trajek te vergelyk. Terwyl die stelsel ly aan die effekte van wegdrywing oor langdurige intreevideos, word dit getoon dat die stelsel wel die lokale beweging van die kamera kan volg. Hierdie proefskrif bevind dat die bal wentelingsalgoritme die oppervlaktes en bygaande rande vir sintetiese puntwolke kan genereer, maar dit is sterk gevoelig vir ruis in sintetiese en werklike datastelle. Op grond van die resultate wat verkry word, word aanbeveel dat die verkrygde puntwolk vooraf verwerk word om ruis te verwyder voordat dit aan die maasgenereringsalgoritme verskaf word, en ’n alternatiewe maasgenereringstegniek moet gebruik word wat meer robuust is ten opsigte van ruis

Dealcoholised wine : motivations, preferences and perceptions of South African Generation Y consumers

Thesis (MCom)--Stellenbosch University, 2022.ENGLISH SUMMARY : Alcohol plays a major role in the daily lives of millions of consumers around the world. It has played a central role throughout the development of humankind and has become one of the most widely produced and consumed substances in the world, with deep social and cultural roots. However, a growth in interest for low and non-alcoholic beverage alternatives has become apparent, believed to be credited to a shift towards health-consciousness and a greater focus on wellness and mental well-being, particularly by Generation Y consumers. Despite the growing interest in the low and non-alcoholic beverage industry, certain products, such as dealcoholised wine, have not seen comparative success compared with other products within this category such as light and alcohol-free beer. In addition, several potential challenges have been identified that may prevent the wider acceptance and growth for low and non-alcoholic beverage products. These potential challenges are believed to be attributed to poor taste, a lack of awareness, a lack of availability, a lack of appeal to male consumers and a general stigma attached to not drinking alcohol. Therefore, there was a need to investigate what motivates Generation Y consumers to purchase dealcoholised wine and the preferences and perceptions that they have about dealcoholised wine. For this study, a two-phased research approach was taken, involving a main quantitative phase, preceded by a qualitative phase. A focus group was conducted to confirm and refine items and assisted in developing a self-administered, non-interactive questionnaire that was used in the quantitative phase of the study. A sample of 626 South African Generation Y male and female dealcoholised wine consumers was obtained through judgement sampling. “Taste”, “price” and “I have tried it before” were identified as the most important considerations for respondents of the realised sample when purchasing dealcoholised wine, with “taste” being significantly more important and different compared to other attributes. Overall, the sample seem to be motivated to purchase dealcoholised wine predominantly for reasons such as “to avoid drinking and driving”, “I like the taste”, “to reduce my alcohol intake” and “to avoid getting drunk”, which are mainly functional in nature. In terms of motives not to purchase dealcoholised wine, respondents of the total realised sample were seemingly most bothered by “limited availability”, “it is difficult to find”, “lower quality than regular wine” and “I dislike the taste”. Lastly, the sample perceive dealcoholised wine as a healthier, but more expensive alternative to wine. A number of differences were found when comparing the motives, preferences and perceptions of South African Generation Y male and female consumers. This pioneering study contributes to the limited existing knowledge in the field of low and non-alcoholic beverages, from a marketing and consumer behaviour perspective. Furthermore, the study provides insights into overcoming existing potential challenges to the wider acceptance of low and non-alcoholic beverages such as dealcoholised wine.AFRIKAANSE OPSOMMING : Alkohol speel ’n groot rol in die daaglikse lewe van miljoene verbruikers oor die wêreld heen. Dit het ’n sentrale rol gespeel in die ontwikkeling van die mens en het een van die mees algemeen geproduseerde en verbruikte substansies in die wêreld geword, met diep sosiale en kulturele wortels. ’n Groeiende belangstelling in lae en nie-alkoholiese drankies is vermoedelik te danke aan ’n beweging na gesondheidsbewustheid en ’n groter fokus op fisiese en geestelike welstand, veral onder verbruikers in Generasie Y. Ten spyte van die toename in belangstelling in die lae en alkohol-vrye drankbedryf, het sekere produkte, soos alkoholvrye wyn, nie vergelykbare sukses ervaar nie in vergelyking met ander produkte in hierdie kategorie soos ligte en alkoholvrye bier. Boonop is verskeie hindernisse geïdentifiseer wat wyer aanvaarding en groei van lae en nie-alkoholiese drankprodukte verhoed. Hierdie hindernisse word toegeskryf aan onbevredigende smaak, ’n gebrek aan bewustheid, ’n gebrek aan beskikbaarheid, ’n gebrek aan aantrekkingskrag vir manlike verbruikers en ’n algemene stigma verbonde daaraan om nie alkohol te drink nie. ‘n Behoefte is dus geïdentifiseer om te ondersoek wat Generasie Y verbruikers motiveer om alkoholvrye wyn te koop en die voorkeure en persepsies wat hulle het oor alkoholvrye wyn. Vir hierdie studie is ’n Twee-fase benadering gebruik wat insluit ’n hoof- kwantitatiewe fase, voorafgegaan deur ’n kwalitatiewe fase. ’n Fokusgroep is gehou ten einde items te bevestig en te verfyn wat gehelp het om ’n self-geadministreerde, nie-interaktiewe vraelys te ontwikkel wat gebruik is in die kwantitatiewe fase van die studie. ’n monster van 626 Suid-Afrikaanse Generasie Y manlike en vroulike verbruikers van alkoholvrye wyn is verkry deur oordeel-monsters. “Smaak”, “prys” en “ek het dit al voorheen probeer” is geïdentifiseer as die belangrikste oorweging vir die lede van die monster-groep wanneer alkoholvrye wyne gekoop is, met “smaak” wat aansienlik belangriker en anders was in vergelyking met ander eienskappe. Algeheel lyk dit asof die lede van die monster-groep gemotiveer was om alkoholvrye wyn te koop hoofsaaklik vir redes soos “om drink en bestuur te vermy”, “ek hou van die smaak”, “om my alkohol-inname te verminder” en “om dronkenskap te vermy”, wat hoofsaaklik funksioneel van natuur is. In terme van motiewe om nie alkoholvrye wyn te koop nie, was respondente van die totaal gerealiseerde monster greop skynbaar veral gepla deur “beperkte beskikbaarheid”, “dit is moeilik om te vind”, “laer kwaliteit as gewone wyn” en “ek hou nie van die smaak nie”. Laastens het die respondente alkoholvrye wyn gesien as ’n gesonder, maar duurder alternatief vir wyn. ’n Aantal verskille is gevind wanneer die motiewe, voorkeure en persepsies van Suid-Afrikaanse Generasie Y manlike en vroulike verbruikers vergelyk is. Hierdie baanbreker-studie dra by tot die beperkte bestaande kennis in die veld van lae en nie-alkoholiese drankies, vanuit ’n bemarking- en verbruikers-perspektief. Die studie verskaf verdere insigte verkry in die oorkoming van bestaande hindernisse tot wyer aanvaarding van lae en nie-alkoholiese drankies soos alkoholvrye wyn.Master

Corporate Social Responsibility in the Zambian mining sector: an overview of three distinctive operational eras

ABSTRACT Corporate Social Responsibility (CSR) within the extractive industry is a relevant and contentious issue globally. Issues pertaining to equality, human rights and sustainable development are pervasive throughout the economic, social and environmental arenas of the extractive industry. There is still not consensus on the definition of CSR regarding the measurement of performance or impact, or how to determine which of the various ‘developmental’ components of the concept – namely economic, social or environment – takes precedent over the other where there are competing interests. This article on CSR in the Zambian Copperbelt uses the experiences of mining communities as stakeholders who have gone through three types and eras of CSR practices within a generation. The Zambian Copperbelt has a history of operating under colonial rule, nationalisation and privatisation. The aim is to interrogate the CSR practices of the three identified eras in the history of the Zambian Copperbelt. The article is based on the findings from a mainly qualitative research approach. The research employed the survey procedure through focus groups, personal interviews and inputs from key informants.The findings are presented by a selection of narratives of CSR experiences from the Zambian Copperbelt mining communities. Consequently, an in depth discussion and analysis reflecting the effects of a CSR enabling environment in the three eras as experienced by community members follows. The paper concludes with a brief overview of the lessons learnt throughout the three eras. OPSOMMING Korporatiewe Sosiale Verantwoordelikheid (KSV) binne die ontginningsindustrie is 'n relevante en omstrede kwessie wêreldwyd. Kwessies met betrekking tot gelykheid, menseregte en volhoubare ontwikkeling is universeel ooglopend binne die ekonomiese-, sosiale- en omgewingsarenas van die mynsektor. Daar is steeds nie konsensus oor die definisie van KSV rakende die meting van prestasie of impak daarvan nie, ook nie hoe om te bepaal watter een van die verskillende "ontwikkelings" komponente van die konsep (naamlik die ekonomiese, sosiale of omgewingsaspek) bevoordeel moet word bo die ander, waar daar mededingende belange is nie. Hierdie artikel oor KSV in die Zambiese Koperstreek gebruik die ervarings van myngemeenskappe as belanghebbendes wat deur drie tipes en tydperke van KSV praktyke gegaan het, binne 'n generasie. Die Zambiese Koperstreek het 'n geskiedenis van die bedrywighede onder koloniale heerskappy, nasionalisering en privatisering. Die doel is om die KSV praktyke van die drie bogenoemde eras te ondersoek deur die geskiedenis van die Zambiese Koperstreek. Hierdie artikel is gebaseer op die bevindinge van 'n hoofsaaklik kwalitatiewe navorsingsbenadering en het gebruik gemaak van fokusgroepe, persoonlike onderhoude en insette deur sleutel informante. Die bevindinge word aangebied deur 'n seleksie van verhale rakende die KSV ervarings van die Zambiese Koperstreek myngemeenskappe. Daarna volg ?n in-diepte bespreking en ontleding rakende die gevolge van 'n KSV bemagtigende omgewing, in die drie eras soos ervaar deur lede van die gemeenskap. Die artikel sluit af met 'n kort oorsig oor die lesse wat geleer is oor die drie eras.https://doi.org/10.19108/KOERS.82.1.228

Towards sustainable futures : exploring ecological learning in early childhood development

Thesis (MPhil)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The end of the 20st and beginning of the 21st century is characterised by a multiplicity of ecological complexities and alterations that are impacting both nature and humankind negatively. Such ecological problems are an indicator of unsustainable living by humans in societies, with inadequate natural resources management. These ecological intricacies are exacerbated by the increasing disinterestedness and detachment of children from the marvels of the natural world resulting in the creation of generations of ecologically unconscious citizens and imbalanced ecosystems. It seems apparent that in this ecological crisis, it is the poor and, in particular, the younger generations that are most affected. In this context; how can the manifest and evolving ecological crisis be reversed? This study is an inquiry into the usefulness of ecological learning in ECD, towards developing conscious future citizens who promote sustainable and ecological balance on the earth. The core objective is to understand current trends, scope, content and methodologies involved in ecological learning and how they may assist in preparing a proecological generation. The study employs a literature review methodology to explore the concept of ecological learning in ECD; examining the application of this paradigm to the sector of ECD through an exploration of the practice of ecological learning in 2 case studies of ECD centres (the Lynedoch EcoVillage and Campus Kindergarten) that place ecological learning at the core of their practice. Using a review of literature on ecological learning and ECD and the two case studies, the study attempts to demonstrate ecological learning practices in ECD centres. The teaching and learning practices in such centres project ECD to be the primary stage whereby ultimate growth, development and learning are created and therefore a vital platform for mentoring an ecologically mindful generation of citizens. However, on the other hand, the study also observes that the scale at which ecological learning is taking place around the world is too negligible to have a large impact in producing a generation of ecologically informed citizens. The study, then, recommends a paradigm shift in the content and methodologies that prioritise ecological learning in ECD both as a way of preserving the ecology and promoting sustainable development. The study therefore suggests, (1) Underpinning ECD with transdisciplinary ecological learning within local contexts (2) Linking ecological learning to ECD may contribute to ‘just transitions’, and (3) Attending to the growing need of new ways of being that can generate connectedness and belonging in a postconsumerist society seem best inculcated at early ages.AFRIKAANSE OPSOMMING: Die einde van die 20ste, en begin van die 21ste eeu word gekenmerk deur ’n magdom ekologiese kompleksiteite en veranderinge wat die natuur en die mensdom (meestal) negatief raak. Hierdie ekologiese probleme dui op onvollhoubare samelewings en natuurlikehulpbron-bestuur. Die ekologiese uitdagings word vererger deur kinders se toenemende onverskilligheid en afsydigheid teenoor die wonders van die natuurlike wêreld, wat generasies van ekologies onbewuste burgers, sowel as ’n ongebalanseerde ekosisteem tot gevolg het. Dit is voorts duidelik dat die huidige ekologiese krisis, laer inkomste groepe en die jonger generasie die ergste raak. Teen hierdie agtergrond, moet ons onsself afvra, hoe die onmiskenbare en ontvouende ekologiese krisis omgekeer kan word? In hierdie studie word daar ondersoek ingestel na die doeltreffendheid van ekologie in die vroeë kindontwikkelings- (VKO) stadium, om burgers op te lewer wat volhoubare en ekologiese ewewig bevorder. Die kernoogmerk is om die huidige tendense in die bestek en inhoud van, metodologieë vir ekologiese leer te verstaan; sowel as hoe dít ’n pro-ekologiese generasie help toerus. Daar word gebruik gemaak van ’n literatuuroorsig, ten einde die konsep van ekologiese-leer in VKO te ondersoek. Die praktiese toepassing daarvan in twee VKO-sentrums, naamlik die Lynedoch-ekodorp en Campus Kindergarten (CK), wat albei ekologiese leer as ’n kernaktiwiteit beskou, ondersoek. Aan die hand van die kritiese literatuuroorsig sowel as die twee gevallestudies, poog hierdie navorsing, om te toon dat VKO-sentrums toenemend ekologiese praktyke erken. Die onderrig- en leerpraktyke in sulke sentrums beskou VKO as die primêre stadium wat uiteindelike groei, ontwikkeling en leer bepaal, en dus is dit ’n uiters belangrike platform om ’n ekologies-bewuste generasie van mentorskap te voorsien. Aan die ander kant is daar ook gevind dat die skaal waarop ekologiese leer wêreldwyd plaasvind, te klein is om enige beduidende impak te hê op die skep van ’n generasie wat ingelig is oor ekologie. Daarom word daar aanbeveel dat daar ’n paradigmaverskuiwing in inhoud en metodologieë moet plaasvind om ekologiese leer in VKO te prioritiseer as ’n manier om die ekologie te bewaar sowel as volhoubare ontwikkeling te bevorder. Die studie dui op die volgende; (1) geïntegreerde leer, tesame met konsekwentheid in die aanbieding van onderwerpe, en die fasilitering van VKOonderwyseropleiding en–diens; (2) die skakel tussen ekologiese opvoeding en die bydrae wat dit tot VKO lewer; (3) om nuwe maniere te vind, waarmee daar ’n skakel gevestig, en ‘n verband getrek kan word, in ‘n post-verbruikers samelewing

Academic honesty: Perceptions of millennial university students and the role of moderating variables

Student academic dishonesty is increasing locally and internationally and universities are devising strategies to address this problem. The first year of academic study lays the foundation for future years of study and, as such, is critical in the establishment of adherence to academic values. As part of a larger project, the perceptions about academic honesty of first-year students belonging to the millennial generation at a large South African public university were obtained with a view to identifying trends in perceptions between the 2011 and 2012 student cohorts as well as the relationship between student sub-groups and perceptions held about academic honesty. The present study also sought to validate the findings of the 2011 study.The population comprised all 22 442 students entering the University for the first time during the 2011 and 2012 academic years. Combined Strategy Sampling, followed by cluster sampling was used to obtain a sample of 5 730 students (3 611 in 2011 and 2 119 in 2012), broadly representative of the institutional population. In this regard, the 2011 sample of Thomas and van Zyl (2012) (3 611 students) was combined with the sample of the present study (2 119). A questionnaire, developed from the literature, comprising 12 ethical statements was used as the survey instrument. The data for the 2012 student sample was compared to that obtained from the Thomas and van Zyl (2011) sample and, by means of Chi-square tests and Standardised Residuals, the statistical association between perceptions held by members of student sub-groups and perceptions about academic honesty was investigated.The sample of both years of first-year students indicated a trend in perceptions and one that pointed to an understanding of the meaning of academic dishonesty yet a regard for it as a relative concept and one that is superseded by, for example, the belief that right and wrong is a matter of personal opinion, that ideas do not belong to anyone and that information is accessible and free. This implies that these students enter academia with perceptions about academic honesty that may differ to those founded on the value authenticity in academia. Differences in opinion were found amongst students of different language groups and the qualification for which they were registered.It is recommended that the values of academia should be reinforced with this student group and that broad pedagogic approaches, whilst reinforcing these values, should be tailored and differentiated according to the specific nature of each faculty and with particular sensitivity to the writing needs of students who belong to different language groups.OPSOMMINGDie insidensie van studente akademiese oneerlikheid is ‘n toenemende probleem beide op nasionale en internasionale vlak en universiteite is besig om strategieë in plek te sit om hierdie problem aan te spreek.   Die eerste studiejaar is ‘n kritieke moment vir die vestiging van gepaste akademiese waardes omdat dit die fondament lê vir die daaropvolgende studiejare.  Die huidige studie vorm deel van ‘n groter projek wat die persepsies van sogenaamde milleniale generasie eerstejaarstudente oor akademiese eerlikheid by ‘n groot publieke universiteit in Suid Afrika ondersoek het.  Die doel van die ondersoek was om tendense in die persepsies van studente wat tussen 2011 en 2012 die universiteit betree het asook die onderlinge verwantskappe tussen verskeie sub-groepe in verband met akademiese eerlikheid te ondersoek.  Die huidige studie het ook gepoog om die bevindinge van die 2011 studie te valideer. Die populasie waaruit die steekproef geneem is het bestaan uit al 22 442 studente wat die Universiteit tydens die 2011 en 2012 akademiese jare vir die eerste keer betree het.  Gekombineerde strategie steekproefneming, gevolg deur trossteekproefneming is gebruik om ‘n steekproef van 5 730 studente (3 611 in 2011 en 2 119 in 2012) te selekteer.  Die steekproef was demografies gesproke verteenwoordigend van die institusionele student profiel.  Vir die doel van hierdie studie is die 2011 steekproef van Thomas en van Zyl (2012) (3 611 studente) en die 2012 steekproef (2 119 studente) gekombineer. ‘n Vraelys wat vanuit die litteratuur ontwikkel is en wat uit 12 eties gelaaide stellings bestaan het, is as navorsingsinstrument gebruik.  Die data van die 2012 steekproef is vergelyk met die data van Thomas en van Zyl (2011) en die chi-kwadraat toets met gestandardiseerde residue is gebruik om die statistiese verband tussen verskillende sub-groepe en hul persepsies oor akademiese eerlikheid te ondersoek. Tendense wat daarop dui dat studente die betekenis van akademiese oneerlikheid verstaan, maar dit as ‘n relatiewe konsep beskou, was waarneembaar in beide steekproewe wat hier ondersoek is.  Die studente het aangedui dat hul oortuiging dat “reg en verkeerd slegs ‘n kwessie van persoonlike oortuiging is” en dat “idees nie aan iemand kan behoort nie maar dat hulle vryelik beskikbaar en bruikbaar moet wees” belangriker is as konsepte wat tradisioneel verband hou met akademiese oneerlikheid.  Dit impliseer dat hierdie studente dikwels die akademie betree met persepsies oor akademiese oneerlikheid wat verskil van die tradisionele akademiese verstaan wat op die belangrikheid van egtheid in die akdedemie gegrond is.  Die huidige studie het verskille in sienings gevind tussen verskillende taalgroepe asook tussen die verskillende studierigtings. Hierdie studie beveel aan dat die waardes wat eie is aan die akademie duidelik gekommunikeer sal word in die groter studentegroep.  Dit moet gedoen word deur algemene pedagogiese benaderings asook op pasgemaakte maniere wat die behoeftes en aard van verskillende fakulteite asook die verskillende skryfbehoeftes van verskillende taalgroepe in ag neem.https://doi.org/10.19108/KOERS.80.1.221

Development of a micro-gas turbine for central receiver concentrating solar power systems

Thesis (PhD)--Stellenbosch University, 2020.ENGLISH ABSTRACT: There is limited access to electricity in much of Southern Africa, yet this region receives some of the highest solar irradiation worldwide. Consequently, there is a huge potential for the deployment of concentrating solar power (CSP) distributed electricity generation systems. The application of gas turbines in central receiver CSP systems combines high concentration ratios of central receiver technology and the ability to scale in size, with inherent gas turbine advantages. This makes these systems ideal for distributed electricity generation applications. However, there are currently no commercial solar-hybrid gas turbine systems readily available off-the-shelf. Through both a theoretical and experimental approach, this study therefore aims to develop a micro gas turbine (MGT) system for central receiver CSP distributed electricity generation applications. The theoretical work involved modeling the performance of a MGT system under solar-hybrid operation, in order to predict the possible operating range and develop suitable operation and control strategies for the MGT system. The experimental work involved designing, building, testing and characterising the performance of an experimental MGT system and then using the obtained test data to validate the predicted performance, as well as assess the technical feasibility of adapting such a system to solar-hybrid operation. The component matching showed a shift of the equilibrium running point on the compressor characteristic, to counter the additional system pressure losses and ensure a useful work output, albeit with a reduced surge margin. Solar-hybrid operation was only possible for a solar share of at least 20 %, while the work output and cycle thermal efficiency drop below standard operation levels beyond certain solar share. In contrast to standard operation, a higher nominal work output of 20 kW, at a lower specific fuel consumption of 0.0004 kg/kWh and a higher cycle thermal efficiency of 8 % was predicted, the latter potentially increasing to 20 % with recuperation. Based on the proposed control strategy of operating the MGT system at the determined solar-hybrid equilibrium running point, sudden changes in solar irradiation were corrected by altering the fuel flow. From the validation of the predicted performance, the predicted MGT system equilibrium running point matched the optimum experimental equilibrium running points, and a similar shift on the compressor characteristic was predicted for varying levels of system pressure losses. The use of turbocharger technology should allow for easy coupling of the individual MGT system components, some of which could be specially designed for solar-hybrid operation. The twin-shaft configuration allows for flexibility in operation, with the added advantage of ease of starting. The large swallowing capacity of the much bigger power turbine should further ensure that the MGT system is insensitive to load variation. The findings from this study should guide operation and control strategies for the proposed, and future solar-hybrid MGT systems, which should in turn contribute to their development and commercialization.AFRIKAANSE OPSOMMING: Alhoewel Suider Afrika van die hoogste sonbestralingsvlakke ter wêreld het, is daar beperkte toegang tot elektrisiteit in die streek. Gevolglik is daar ’n beduidende potensiaal vir die ontplooiing van gekonsentreerde sonkrag (CSP) verspreide elektrisiteitsopwekking stelsels. Die gebruik van gasturbines in sentrale ontvanger CSP stelsels kombineer die hoë konsentrasievlakke van sentrale ontvanger tegnologie en die vermoë om te skaleer, met die inherente voordele van gasturbines. Dit maak hierdie stelsels ideaal vir verspreide elektrisiteitsopwekking toepassings. Daar is egter tans geen kommersiële van-die-rak son-hibriede gasturbine stelsels beskikbaar nie. Die studie poog om deur middel van beide ’n teoretiese en eksperimentele benadering ’n mikrogasturbine (MGT) stelsel vir sentrale ontvanger CSP verspreide elektrisiteitsopwekkings toepassings te ontwikkel. Die teoretiese werk het die modellering van ’n MGT stelsel onder son-hibriede werking behels, ten einde die moontlike bedryfsgebied te voorspel en om gepaste bedryfs- en beheer strategieë vir die MGT te ontwikkel. Die eksperimentele werk het die ontwerp, bou, toets en karakterisering van ’n eksperimentele MGT stelsel behels. Die toetsdata is gebruik om die voorspelde werksverrigting van die stelsel te valideer, sowel as om die tegniese haalbaarheid van die aanpassing van so ’n stelsel vir son-hibriede werking te bepaal. Die stelselbalansering vir son-hibriede toepassing het gewys dat die ekwilibrium werkspunt op die kompressor karakteristiek skuif, ten einde die addisionele stelsel verliese teen te werk, asook om steeds ’n bruikbare drywingsuitset te verseker, alhoewel teen ’n vermindering in staakwydte. Son-hibriede werking was net moontlik vir ’n sonaandeel van ten minste 20 %, terwyl die werksuitset en siklus termiese benuttingsgraad geval het tot onder standaard bedryfsvlakke bokant ’n sekere sonaandeel. In vergelyking met standaard werking van die MGT, is ’n hoër nominale drywingsuitset van 20 kW, teen ’n laer spesifieke brandstofverbruik van 0.0004 kg/kWh en ’n hoër termiese benuttingsgraad van 8 % voorspel. Laasgenoemde kan potensieel tot 20 % verhoog word met tussenverhitting (recuperation). Gebaseer op die voorgestelde beheer strategie om die MGT stelsel by die spesifieke son-hibriede ekwilibrium werkspunt te bedryf, is daar vir skielike verandering in die sonbestraling gekorrigeer deur die brandstofvloei aan te pas. Uit die validasie van die voorspelde werksverrigting is gevind dat die voorspelde MGT werkspunt ooreenstem met die eksperimentele optimum eksperimentele ekwilibrium werkspunt en dat ’n soortgelyke skuif in die kompressor karakteristiek voorspel is vir wisselende vlakke van stelsel drukverlies. Die gebruik van bestaande turbo-aanjaer tegnologie behoort voorsiening te maak vir die vereenvoudigde koppeling van die MGT stelsel komponente, waarvan sommige doelontwerp kan word vir sonhibriede werking. Die dubbel-as konfigurasie lei tot buigbare stelselwerking, asook die bykomende voordeel dat die stelsel maklik in werking gestel kan word. Die groot vloeikapasiteit van die veel groter drywingsturbine behoort ook te verseker dat die MGT stelsel onsensitief is vir lasvariasies. Die bevindinge van hierdie studie sal as gids dien vir die opstel van bedryfs- en beheer strategieë vir die voorgestelde en toekomstige son-hibriede MGT stelsels, wat weer ’n bydrae sal maak tot die ontwikkeling en kommersialisering van hierdie stelsels.Doctora

Valuation of pumped storage in capacity expansion planning – a South African case study

Thesis (MEng)--Stellenbosch University, 2022.ENGLISH ABSTRACT: On the South African grid, pump storage schemes offer a range of benefits which can assist in the integration of increased variable renewable energy generation. The Integrated Resource Plan for South Africa currently proposes adding gas turbines and batteries to the future grid for peaking capacity and increased flexibility, with no added pump storage schemes. This thesis investigates the value of the services and contributions pumped storage provides the grid, the capital costs and history of this technology in order to determine its potential future role. The research aims to address the possible misconception of limited pump storage scheme site availability by providing an overview of site feasibility studies, including estimated cost projections and utilises these values in an energy optimisation model to investigate the economic case for pump storage.AFRIKAANSE OPSOMMING: Op die Suid-Afrikaanse netwerk bied pompopbergingskemas 'n verskeidenheid voordele wat kan help met die integrasie van verhoogde opwekking van veranderlike hernubare energie. Die geïntegreerde hulpbronplan vir Suid-Afrika stel tans voor dat gasturbines en batterye by die toekomstige netwerk gevoeg moet word vir 'n maksimum kapasiteit en verhoogde buigsaamheid, sonder bykomende skema's vir die stoor van pompe. Hierdie referaat ondersoek die waarde van die dienste en bydraes wat gepomp word, bied die netwerk, die kapitaalkoste en die geskiedenis van hierdie tegnologie om die potensiële toekomstige rol daarvan te bepaal. Die navorsing is daarop gemik om die moontlike wanopvatting van die beskikbaarheid van beperkte pompopbergingsterreine aan te spreek deur 'n oorsig te gee van haalbaarheidstudies op die terrein, insluitend geskatte kosteprojeksies, en gebruik hierdie waardes in 'n energie-optimaliseringsmodel om die ekonomiese geval vir pompopberging te ondersoek.Master

Light sheet fluorescence microscopy

Thesis (MSc)--Stellenbosch University, 2021.ENGLISH ABSTRACT: Light sheet fluorescence microscopy is a powerful tool within the in field of microscopy. The inherent advantages over other fluorescence microscopy techniques include high sectioning capabilities, reduced photo-damage in the sample and short data acquisition times. In this thesis, a light sheet microscope is developed which allows the users to tailor the parameters of the light sheet for various applications, by implementing the use of a spatial light modulator (SLM) to dynamically alter the shape of the light sheet. Three different techniques for light sheet generation are investigated, namely by the use of a cylindrical lens, using an SLM, and by digitally scanning a beam. Each of the techniques were characterised. Using the light sheets, three dimensional fluorescence images are obtained. These three dimensional images are analysed to determine the imaging capabilities of the system, and the deconvolution of these images are implemented for image restoration. The result is a multi-purpose light sheet microscope for use in biological imaging.AFRIKAANSE OPSOMMING: Ligblad fluoressensiemikroskopie is 'n kragtige tegniek binne die veld van mikroskopiese. Die voordele bo ander fluoressensie-mikroskopie-tegnieke sluit in 'n hoë snyvermoë, verminderde fotoskade in die monster en kort dataverkrygingstye. In hierdie proefskrif word 'n ligbladmikroskoop ontwikkel wat gebruikers in staat stel om die parameters van die ligblad vir verskillende toepassings aan te pas deur die gebruik van 'n ruimtelike ligmodulator (RLM) om die vorm van die ligblad dinamies te verander. Drie verskillende tegnieke vir ligblad vorming word ondersoek, naamlik deur die gebruik van 'n silindriese lens, met behulp van 'n RLM, en deur 'n ligstraal digitaal te skandeer. Elk van die tegnieke word gekarakteriseer. Met behulp van die ligblad word driedimensionele fluoressensiebeelde verkry. Hierdie driedimensionele beelde word geanaliseer om die beeldvermoëns van die stelsel te bepaal, en die dekonvolusie van hierdie beelde word geimplementeer vir beeldherstel. Die resultaat is 'n veeldoelige ligbladmikroskoop vir beeldvorming in biologie.Master