SUNScholar ETD Loader Community: Reviewed Submissions March 2012

Use, physiology and genetic characterisation of selected natural populations of Adansonia Digitata in Malawi

Mon, 28 Nov 2011 05:58:58 GMT

Title: Use, physiology and genetic characterisation of selected natural populations of Adansonia Digitata in Malawi

Author: Munthali, Chimuleke Rowland Yagontha

Supervisor(s): Chirwa, P. W.; Akinnifesi, F. K.; Meincken, Martina

Abstract: ENGLISH ABSTRACT: See full text for abstract; AFRIKAANSE OPSOMMING: Sien volteks vir opsomming

Degree: Thesis (PhD (For) (Forest and Wood Science))--Stellenbosch University, 2012.

Modelling of the motion of a mixture of particles and a Newtonian fluid

Fri, 25 Nov 2011 15:04:28 GMT

Title: Modelling of the motion of a mixture of particles and a Newtonian fluid

Author: Wilms, Josefine Maryna

Supervisor(s): Smit, G. J. F.; Diedericks, G. P. J.

Abstract: ENGLISH ABSTRACT: See full text for abstract; AFRIKAANSE OPSOMMING: Sien volteks vir opsomming

Degree: Thesis (PhD (Mathematical Sciencces))--Stellenbosch University, 2012.

The anatectic history of Archaean metasedimentary granulites from the Ancient Gneiss Complex, Swaziland

Wed, 16 Nov 2011 13:08:37 GMT

Title: The anatectic history of Archaean metasedimentary granulites from the Ancient Gneiss Complex, Swaziland

Author: Taylor, Jeanne

Supervisor(s): Stevens, Gary

Abstract: ENGLISH ABSTRACT: This study is an investigation of the anatectic history of high-grade paragneisses from the Ancient Gneiss Complex (AGC) in Swaziland. The work involved an integrated field, metamorphic, geochemical, geochronological and structural study of metasedimentary granulites from three separate, but spatially related areas of outcrop in south-central Swaziland, which were subjected to multiple high-grade partial melting events throughout the Meso- to Neoarchaean. The project has aimed to constrain the age(s) and conditions of metamorphism, so as to contribute to the understanding of geodynamic processes in the Barberton and AGC granite-greenstone terranes, as well as to investigate certain physical and chemical aspects of anatexis in the migmatites. The metamorphic record retained in these rocks, constrained by phase equilibria modelling as well as zircon and monazite SHRIMP and LA-ICP-MS geochronology, informs on the state of the mid- to lower-crust of the southeastern Kaapvaal Craton during key events associated with early lithosphere assembly and crustal differentiation. It also suggests that the region is comprised of more than one high-grade terrane. Two of the areas investigated experienced high-temperature metamorphism at ca. 3.23-3.21 Ga, in addition to a major 830-875º C, 6.5-7.6 kbar anatectic event at ca. 3.11-3.07 Ga. Intermediate and younger high-temperature events are recorded at ca. 3.18 Ga, ca. 3.16 Ga and 2.99 Ga. The timing of these metamorphic events coincided with the amalgamation of the eastern domain of the proto-Craton via subduction and accretion of micro-continental fragments at ca. 3.23 Ga, including the Barberton Greenstone Belt (BGB) and AGC terranes, as well as discrete episodes of crustal differentiation and potassic granitic magmatism between ca. 3.23 and 3.10 Ga. The third area investigated holds no record of Mesoarchaean metamorphism, but instead experienced a 830- 855 ºC, 4.4-6.4 kbar partial melting episode at ca. 2.73 Ga. This broadly coincided with the formation of a large continental flood basalt province, the ca. 2.71 Ga Ventersdorp LIP, and widespread intracratonic granitic magmatism on the Craton towards the end of the Neoarchaean. An explanation for the contrast in metamorphic record in the two terranes may be that the 2.71 Ga granulites represent a much younger sedimentary succession, and that granulites from the older terrane were left too restitic, after substantial partial melting during the Mesoarchaean, to record subsequent high-grade events. Finally, this study documents the details of S-type granitic magma production and extraction from a typical metapelitic source. Using the 2.73 Ga granulites from the AGC as a natural field laboratory, a case is made for the selective entrainment of peritectic garnet to the magma as a mechanism for generating relatively mafic, peraluminous S-type granite compositions. The work demonstrates the evolution of entrained peritectic garnet in such magmas, and is in strong support of a ‘peritectic phase entrainment’ process by which relatively mafic granite magmas are produced from melts which, in theory, should be highly leucocratic.; AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die anatektiese geskiedenis van hoëgraadse metasedimentêre gneise uit die Ancient Gneiss Complex (AGC) in Swaziland. Die werk behels 'n geïntegreerde veld, metamorfiese, geochemiese, geochronologiese en strukturele studie van metasedimentêre granuliete van drie afsonderlike, maar ruimtelik verwante gebiede in suid-sentraal Swaziland, wat aan verskeie hoëgraadse anatektiese gebeure onderworpe was gedurende die Meso-tot Neoargeïese tydsperiode. Die studie is daarop gemik om die ouderdomme en die kondisies van metamorfose vas te stel, om sodoende by te dra tot die begrip van die geodinamiese prosesse in die Barberton en AGC granietgroensteen terrein, asook om sekere fisiese en chemiese aspekte van die anatektiese proses te ondersoek. Die metamorfe rekord, bepaal deur mineraal ewewigsmodellering sowel as sirkoon en monasiet SHRIMP en LA-ICP-MS geochronologie, belig die toestand van die middel-tot laer-kors van die suidoostelike Kaapvaal Kraton tydens vroeë litosfeer samesmelting en differensiasie. Dit stel ook voor dat die streek uit meer as een hoëgraadse terrein bestaan. Twee van die gebiede het hoë-temperatuur metamorfose by 3.23-3.21 Ga ervaar, asook 'n hoof 830-875 ° C, 6.5-7.6 kbar anatektiese gebeurtenis by 3.11-3.07 Ga. Intermediêre en jonger hoë-temperatuur gebeure was ook by 3.18 Ga, 3.16 Ga en 2.99 Ga geregistreer. Die metamorfose van die gebied stem ooreen met die samesmelting van die oos Kaapvaal Kraton domein deur subduksie en aanwas van mikro-kontinente by 3.23 Ga, insluitend die Barberton en AGC terreine, asook diskrete episodes van kors differensiasie en kalium-ryke graniet magmatisme tussen 3.23 en 3.10 Ga. Die derde gebied hou geen rekord van Mesoargeïkum metamorfose nie. In plaas daarvan het dit 'n 830-855 ° C, 4.4-6.4 kbar anatektiese episode by 2.73 Ga ervaar, wat ooreenstem met die vorming van 'n groot kontinentale vloedbasalt provinsie, die 2.71 Ga Ventersdorp Supergroep, en wydverspreide intrakratoniese graniet magmatisme teen die einde van die Neoargeïkum. 'n Moontlike verduideliking vir die kontras in metamorfe rekord in die twee terreine mag wees dat die 2.71 Ga granuliete 'n jonger sedimentêre afsetting verteenwoordig, en dat granuliete van die ouer terrein te restieties gelaat was na aansienlike anateksis in die Mesoargeïkum, om daaropvolgende hoëgraadse gebeure te registreer. Ten slotte, hierdie studie dokumenteer die besonderhede van S-tipe graniet magma produksie en ontginning van 'n tipiese metasedimentêre bron. Die 2.73 Ga granuliete word gebruik as 'n natuurlike veld laboratorium om die selektiewe optel-en-meevoering van peritektiese granaat tot die magma te ondersoek. Die werk toon die evolusie van peritektiese granate in sulke magmas aan, en ondersteun lewering van relatiewe mafiese graniet magmas deur 'n ‘peritektiese fase optel-en-meevoerings’ proses.

Degree: Thesis (DSc (Earth Sciences))--Stellenbosch University, 2012

Technology assessment of renewable energy sustainability in South Africa

Tue, 27 Sep 2011 10:23:33 GMT

Title: Technology assessment of renewable energy sustainability in South Africa

Author: Musango, Josephine Kaviti

Supervisor(s): Brent, Alan C.; Amigun, Bamikole; Pretorius, Leon; Muller, Hans

Abstract: ENGLISH ABSTRACT: Technology assessment has changed in nature over the last four decades. It changed from an analytical tool for technology evaluation, which depends heavily on quantitative and qualitative modelling methodologies, into a strategic planning tool for policy-making concerning acceptable new technologies, which depends on participative policy problem analysis. The goal of technology assessment today is to generate policy options for solutions of organisational and societal problems, which at the operational level, utilise new technologies that are publicly acceptable; that is, viable policy options. Energy technology assessment for sustainability is inherently a complex and dynamic process that requires a holistic and transdisciplinary approach. In the South Africa context, specifically, there is no formal and coherent approach to energy technology assessment from a sustainability perspective. Without a formal comprehensive or well integrated technology assessment approach to evaluate the sustainability of any technology, the policy-makers, technology designers, and decision-makers are faced with difficulty in terms of making reasoned decisions about the appropriate technology options. This study developed a framework that incorporates a technology assessment approach, namely, system dynamics, within the broader scope of technology development for sustainability. The framework, termed the Systems Approach to Technology Sustainability Assessment (SATSA), integrates three key elements: technology development, sustainable development, and a dynamic systems approach. The study then provides a guiding process of applying the framework to energy technology assessment theory and practice within the context of sustainable development. Biodiesel, a cleaner burning replacement fuel, argued to potentially contribute to sustainable development, is used for the demonstration. Biodiesel development entails complex interactions of actors such as the technology developers, government at different levels, communities, as well as the natural environment. Different actions or responses in the greater system might hinder or undermine the positive effects of such a development. Based on the SATSA framework, a Bioenergy Technology Sustainability Assessment (BIOTSA) model was developed. The BIOTSA model was used to test the outcomes of a proposed biodiesel production development in the Eastern Cape Province of South Africa on selected sustainability indicators. In addition, some policy scenarios were tested to compare how they assist in improving the selected indicators. The BIOTSA model results are useful in comparing dynamic consequences resulting from a proposed biodiesel production development and the respective policies and decisions that may arise from such a development. The testing and validation of the BIOTSA model was carried out based on structural validity, behavioural validity, and expert opinion. Potential policy scenario outcomes and their implication, on the selected sustainability indicators, were also tested. The opinions of the selected stakeholders indicated that the BIOTSA model was useful in providing an understanding of the potential impacts of the biodiesel development on selected sustainability indicators in the Eastern Cape Province. Thus, the SATSA framework can be applied for assessing sustainability of other renewable energy technologies. In addition, system dynamics provide a useful and a feasible dynamic systems approach for energy technology sustainability assessment. Finally, the model building process and transdisciplinary nature of this study enabled the identification of the potential problems that could arise during the biodiesel production development. In addition, gaps in data and knowledge were identified and the recommendation for future work in this field is highlighted. Nevertheless, the findings of the BIOTSA model could inform policy- and decision-making in biodiesel production development in South Africa. The development of similar models for other renewable energy development efforts is thus recommended. The current efforts to facilitate the large-scale roll out of concentrated solar thermal technologies in Southern Africa, for example, would require the development of a Solar Thermal Technology Sustainability Assessment (SOTTSA) model.; AFRIKAANSE OPSOMMING: Die aard van tegnologie assessering het in die afgelope vier dekades verander. Dit het verander ten opsigte van ’n analitiese hulpmiddel vir tegnologie evaluering, wat hoofsaaklik staatmaak op kwalitatiewe en kwantitatiewe modelleringsmetodiek, na ’n strategiese beplanningshulpmiddel vir beleidvorming met betrekking tot nuwe aanvaarbare tegnologieë, wat afhanklik is van ’n deelnemende beleidsprobleem analise. Vandag se doel vir tegnologie assessering is om beleidsopsies vir oplossings van organisatoriese en sosiale probleme te genereer, wat op operasionele vlak gebruik maak van nuwe tegnologieë wat deur die publiek aanvaar is; met ander woorde, lewensvatbare beleidsopsies. Energie tegnologie assessering vir volhoubaarheid is sonder twyfel ’n komplekse en dinamiese proses wat ’n holistiese en transdisiplinêre benadering benodig. In die Suid- Afrikaanse konteks is daar geen formele en samehangende benadering tot tegnologie assessering vanaf ’n volhoubaarheidsperspektief nie. Beleidsmakers, tegnologie ontwerpers en besluitnemers mag sukkel om beredenerende besluite te neem oor die toepaslike tegnologie opsies sonder ’n formele omvattende of goed geïntegreerde tegnologie assesseringsbenadering om die volhoubaarheid van enige tegnologie te evalueer. Hierdie studie het ’n raamwerk ontwerp wat die tegnologie assesseringsbenadering inkorporeer binne die breë bestek van tegnologiese ontwikkeling vir volhoubaarheid naamlik, stelsel dinamika. Die raamwerk, genoem die Sisteem Benadering tot Tegnologie Volhoubaarheidsassessering (SBTVA) integreer drie sleutelelemente: tegnologiese ontwikkeling, volhoubaarheidsontwikkeling, en ŉ dinamiese stelsels benadering. Verder verskaf die studie ’n leidende proses te opsigte van die toepassing van die raamwerk tot energie tegnologie assesseringsteorie en praktyk binne die konteks van volhoubaarheidsontwikkeling. Biodiesel word gebruik vir die demonstrasie omdat dit gereken word as ’n skoner plaasvervanger vir brandstof en daar aangevoer word dat dit ’n potensiële bydraer tot volhoubaarheidsontwikkeling is. Die ontwikkeling van biodiesel behels komplekse interaksie tussen verskeie akteurs soos tegnologiese ontwikkelaars, die regering op verskillende vlakke, gemeenskappe asook die natuurlike omgewing. Verskeie aksies of reaksies in die groter sisteem mag dalk die positiewe effek van so ontwikkeling ondermyn of verhinder. ’n Biodiesel Tegnologiese Volhoubaarheidsassessering (BIOTVA) model is ontwerp gebaseer op die SBTVA raamwerk. Die BIOTVA model is gebruik om die uitkomste op geselekteerde volhoubaarheidsaanduiders van ’n voorgestelde biodiesel produksie ontwikkeling in die Oos- Kaap Provinsie van Suid-Afrika te toets. Buiten vir die voorafgaande is sekere beleidtoekomsblikke ook getoets om te vergelyk hoe hulle sal help om die geselekteerde aanwysers te verbeter. Die BIOTVA model resultate is behulpsaam in die vergelyking van dinamiese gevolge wat voortspruit uit die voorgestelde biodiesel produksie ontwikkeling asook die onderskeie beleide en besluite wat mag ontstaan van so ’n ontwikkeling. Die toetsing en bekragtiging van die BIOTVA model was uitgevoer gebaseer op strukturele geldigheid, gedragsgeldigheid, en kundige opinie. Potensiële beleidtoekomsblikke uitkomste en die nagevolge, ten opsigte van die geselekteerde volhoubaarheidsaanduiders, is ook getoets. Die opinies van die geselekteerde aandeelhouers het aangedui dat die BIOTVA model bruikbaar is om ’n beter begrip te verskaf ten opsigte van die potensiële impak wat die biodiesel ontwikkeling op geselekteerde volhoubaarheidsaanduiders in die Oos-Kaap Provinsie sal hê. As gevolg hiervan kan die SBTVA raamwerk toegepas word om die volhoubaarheid van ander herwinbare energie tegnologieë te assesseer. Buiten die voorafgaande kan stelsel dinamika ’n bruikbare en uitvoerbare dinamiese stelselbenadering vir energie tegnologie volhoubaarheidsassessering verskaf. Ten slotte, die model bouproses en transdisiplinêre aarde van die studie het gehelp om potensiële probleme wat kan voorkom tydens die biodiesel produksie ontwikkeling te identifiseer. Daarby is gapings in data en kennis ook geïdentifiseer en die aanbevelings vir verdere studie in die veld is uitgelig. Nieteenstaande kan die bevindings van die BIOTVA model beleidmakers en besluitnemers in die biodiesel produksie ontwikkeling van Suid- Afrika inlig. Die ontwikkeling van soortgelyke modelle vir ander herwinbare energie ontwikkelingspogings word aanbeveel. As voorbeeld sal die huidige pogings om die grootskaalse uitrol van gekonsentreerde son termiese tegnologieë in Suider-Afrika te fasiliteer die ontwikkeling van ’n Son Termiese Tegnologie Volhoubaarheidsassesering (SOTTVA) model benodig.

Degree: Please download the required VENSIM software from: http://www.vensim.com/freedownload.html; Thesis (PhD (School of Public Leadership))--University of Stellenbosch, 2012.