A combinatorial analysis of barred preferential arrangements
- Authors: Nkonkobe, Sithembele
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/36228 , vital:24530
- Description: For a non-negative integer n an ordered partition of a set Xn with n distinct elements is called a preferential arrangement (PA). A barred preferential arrangement (BPA) is a preferential arrangement with bars in between the blocks of the partition. An integer sequence an associated with the counting PA's of Xn has been intensely studied over a century and a half in many different contexts. In this thesis we develop a unified combinatorial framework to study the enumeration of BPAs and a special subclass of BPAs. The results of the study lead to a positive settlement of an open problem and a conjecture by Nelsen. We derive few important identities pertaining to the number of BPAs and restricted BPAs of an n element set using generating- functionology. Later we show that the number of restricted BPAs of Xn are intricately related to well-known numbers such as Eulerian numbers, Bell numbers, Poly-Bernoulli numbers and the number of equivalence classes of fuzzy subsets of Xn under some equivalent relation.
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- Date Issued: 2016
A critical analysis of agricultural innovation platforms among small-scale farmers in Hwedza communal area, Zimbabwe
- Authors: Mahiya, Innocent Tonderai
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/596 , vital:19973
- Description: Agricultural research has existed for many decades at national and global levels and research-based agricultural interventions, often driven by the state, have taken place across Africa over an extended period. But, overall, these interventions have not generated the high potential and kinds of outcomes expected of them in terms of enhancing agricultural productivity amongst small-scale farmers and improving the quality of their agrarian lives. In the context of neoliberal restructuring globally, new forms of agricultural interventions have arisen which highlight the significance of more participatory methodologies in which non-governmental organisations become central. One such methodology rests on the notion of an agricultural innovation platform which involves bringing on board a diverse range of actors (or stakeholders) which function together to generate agricultural knowledge and practices suitable to the needs of a particular small-scale farming community, with the small-scale farmers expected to be key actors in the platform. Such platforms are now being implemented in specific rural sites in Zimbabwe, including in communal areas in the district of Hwedza where farming activities have for many years now being in large survivalist in character. The objective of this thesis is to critically analyse the agricultural innovation platforms in Hwedza, but not in the sense of assessing the impact of the platforms on agricultural productivity. Rather, the thesis examines the multi-faceted social interactions and relationships embodied in the innovation platform process. In pursuing this, I rely heavily – but in a critical manner – on interface analysis as set out by Norman Long. The fieldwork for the Hwedza involved an interpretative-qualitative methodology based on methods such as in-depth interviews, focus group discussions, questionnaires and observations. The major finding of the thesis is that the agricultural innovation platforms, at least as implemented in Hwedza, do challenge top-down approaches to agricultural interventions by unlocking the possibility of multiple pathways of inclusion and particularly for small-scale farmers but that, simultaneously, they also involve processes marked by divergences, exclusions, tensions and conflicts which may undermine the legitimacy and effectiveness of the platforms.
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- Date Issued: 2016
A Foucauldian analysis of discourses shaping perspectives, responses, and experiences on the accessibility, availability and distribution of condoms in some school communities in Kavango Region
- Authors: Ngalangi, Naftal Sakaria
- Date: 2016
- Subjects: Foucault, Michel, 1926-1984 -- Methodology , Condom use -- Namibia , Sex instruction for teenagers -- Namibia , HIV infections -- Prevention -- Namibia , AIDS (Disease) -- Prevention -- Namibia , Education, Secondary -- Namibia , Teenage pregnancy -- Namibia , Sexual abstinence -- Moral and ethical aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2061 , http://hdl.handle.net/10962/d1019990
- Description: Condom use is promoted as an effective method for prevention and contraception for people who practice or are at risk of practicing high-risk sexual behaviors. According to the UNAIDS (2009) report, condoms are the only resource available to prevent the sexual spread of the HI-Virus; and with regard to family planning, the same report proposes that condoms expand the choices, have no medical side effects, and thus provide dual protection against pregnancy and disease. However, in Africa as elsewhere in the world, condom use has been fiercely debated. The debates on the accessibility, availability and distribution of condoms in schools are not new nor are they uncontested. In Namibia, the HIV and AIDS policy in education does not explain how, when and by whom condoms should be made available to learners. This leaves it to schools to decide on how (and whether) to make condoms available to learners. As a result, individual school‘s choices not only vary, but are mediated by different factors that are not always in the best interest of learners who, as the foregoing discussion suggests, continue to participate in behaviour that, amongst other things, puts them at risk of HIV infection and falling pregnant. Relying on Foucault‘s theory of discourses, this study investigated the dominant discourses that shape learner, teacher, parent religious and traditional leader and traditional healer perspectives, responses, and experiences with regard to the accessibility, availability, and distribution of condoms in school. The study was conducted in nine schools in Kavango Region in Namibia using a mixed methods approach. The study used triangulation in the data collection process through the use of questionnaires where 792 learners participated in this component, and focus group discussions and individual interviews targeting four groups namely, learners, teachers, parents and religious leaders, traditional leaders and traditional healers. The quantitative data were analyzed using the Statistical Packages for Social Sciences (SPSS), and findings from the focus group discussions and individual interviews were analyzed identifying themes and patterns and then organizing them into coherent categories with sub-categories. The study revealed that the majority of adult participants opposed the idea of making condoms available in schools; advocating abstinence instead. This was despite evidence on the prevalence of sexual activity amongst youth in the community. Reasons had to do with various competing and hierarchized discourses operating to shape participant beliefs, perspectives, and responses in a highly regulated and surveilled social and cultural context. Put differently, the dominant discourses invoked a particular sexual subject; authorized and legitimated who invoked such a subject; who was and was not allowed to speak on sexual matters; as well as how sexual matters were brought into the public space of schools. Such authorization and legitimation regulated the discursive space in which discussions on sexual health, safe sex, and resources such as condoms were permitted; with negative consequences for the sexual well-being of youth in Kavango Region. The study also highlighted the tension between freedom, choice, and rights, showing how complex in fact is decision to make condoms available in school. On the one hand, teenagers positioned themselves as capable subjects who had the right to exercise choice over their sexual lives. Requesting parent consent was thus viewed as a violation of this right to choose. Such a position displayed authority and agency by learners that was pitted against views amongst adults in this study that positioned youth as having no agency. In their view, youth (a) were still children and thus innocent and pure, (b) ought to abstain, and (c) were difficult to control given the modern context. Adults believed that early sexual involvement by learners did not result from lack of vigilance and control on their part, but rather from exposure to modern social mores. The study concluded that (a) schools remain difficult spaces not only for mediating discussions of sex and sexuality, but also for providing resources to mitigate sexual risk amongst leaners, (b) in highly regulated societies, dominant religious discourses are produced and reproduced in and through existing institutions such as family, church, and schools; highlighting how these serve to normalize beliefs and perspectives, (c) the dominant discourses shaping communities in which schools find themselves remain inconsistent with school discourses that are shaped by modernist conceptions of childhood and youth, and (b) adult choices to sanction and obstruct schools from making condoms available (and in the case of teachers, not accessible and distributable) put the very children at risk that they propose to be protecting.
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- Date Issued: 2016
A framework for grain commodity trading decision support in South Africa
- Authors: Ayankoya, Kayode Anthony
- Date: 2016
- Subjects: Grain trade -- South Africa Commodity exchanges -- South Africa Food industry and trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11437 , vital:26925
- Description: In several countries around the world, grain commodities are traded as assets on stock exchanges. This indicate that the market and effectively the prices of the grain commodities in such countries, are controlled by several local and international economic, political and social factors that are rapidly changing. As a result, the prices of some grain commodities are volatile and trading in such commodities are prone to price-related risks. There are different trading strategies for minimising price-related risks and maximising profits. But empirical research suggests that making the right decision for effective grain commodities trading has been a difficult task for stakeholders due to high volatility of grain commodities prices. Studies have shown that this is more challenging among grain commodities farmers because of their lack of skills and the time to sift through and make sense of the datasets on the plethora of factors that influence the grain commodities market. This thesis focused on providing an answer for the main research problem that grain farmers in South Africa do not take full advantage of all the available strategies for trading their grain commodities because of the complexities associated with monitoring the large datasets that influence the grain commodities market. The main objective set by this study is to design a framework that can be followed to collect, integrate and analyse datasets that influence trading decisions of grain farmers in South Africa about grain commodities. This study takes advantage of the developments in Big Data and Data Science to achieve the set objective using the Design Science Research (DSR) methodology. The prediction of future prices of grain commodities for the different trading strategies was identified as an important factor for making better decisions when trading grain commodities and the key factors that influence the prices were identified. This was followed by a critical review of the literature to determine how the concepts of Big Data and Data Science can be leveraged for an effective grain commodities trading decision support. This resulted in a proposed framework for grain commodities trading. The proposed framework suggested an investigation of the factors that influence the prices of grain commodities as the basis for acquiring the relevant datasets. The proposed framework suggested the adoption of the Big Data approach in acquiring, preparing and integrating relevant datasets from several sources. Furthermore, it was suggested that algorithmic models for predicting grain commodities prices can be developed on top of the data layer of the proposed framework to provide real-time decision support. The proposed framework suggests the need for a carefully designed visualisation of the result and the collected data that promotes user experience. Lastly, the proposed framework included a technology consideration component to support the Big Data and Data Science approach of the framework. To demonstrate that the proposed framework addressed the main problem of this research, datasets from several sources on trading white maize in South Africa and the factors that influence market were streamed, integrated and analysed. Backpropagation Neural Network algorithm was used for modelling the prices of white maize for spot and futures trading strategies were predicted. There are other modelling techniques such as the Box-Jenkins statistical time series analysis methodology. But, Neural Networks was identified as more suitable for time series data with complex patterns and relationships. A demonstration system was setup to provide effective decision support by using near real-time data to provide a dynamic predictive analytics for the spot and December futures contract prices of white maize in South Africa. Comparative analysis of predictions made using the model from the proposed framework to actual data indicated a significant degree of accuracy. A further evaluation was carried out by asking experienced traders to make predictions for the spot and December futures contract prices of white maize. The result of the exercise indicated that the predictions from the developed model were much closer to the actual prices. This indicated that the proposed framework is technically capable and generally useful. It also shows that the proposed framework can be used to provide decision support about trading grain commodities to stakeholders with lesser skills, experience and resources. The practical contribution of this thesis is that relevant datasets from several sources can be streamed into an integrated data source in real-time, which can be used as input for a real-time learning algorithmic model for predicting grain commodities prices. This will make it possible for a predictive analytics that responds to market volatility thereby providing an effective decision support for grain commodities trading. Another practical contribution of this thesis is a proposed framework that can be followed for developing a Decision Support System for trading in grain commodities. This thesis made theoretical contributions by building on the information processing theory and the decision making theory. The theoretical contribution of this thesis consists of the identification of Big Data approach, tools and techniques for eradicating uncertainty and equivocality in grain commodities trading decision making process.
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- Date Issued: 2016
A framework for the inclusion of students with visual impairments: a case of a Zimbabwe state university
- Authors: Manyumwa, Ennie
- Date: 2016
- Subjects: Inclusive education -- Zimbabwe Students with disabilities -- Education (Higher) -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/29805 , vital:30780
- Description: The aim of this study was to explore the experiences of students with visual impairments in a selected state university in Zimbabwe in order to develop a framework for their inclusion. The study was necessitated by the increased enrolment of students with visual impairments in universities worldwide in response to inclusion in education and the continuous search for the best placement model for students with disabilities. Studies conducted internationally show that students with visual impairments have unique learning needs which must be addressed if their inclusion in universities is to be successful. The study was informed by Bronfenbrenner’s ecological and Bandura’s agentic theories, both of which stress the bi-directional relationship between an individual and the environment. The transformative paradigm which guided this study, lays emphasis on the need to improve the social situation of individuals with disabilities in order to bring about a more equitable society. Since the study intended to gain an understanding of how students with visual impairments interpret their experiences within a selected state university in Zimbabwe which practices inclusion, the qualitative case study design was used. Purposeful sampling was also used in the selection of both the university studied and the participants. Data generation methods employed included the semi-structured interview, photo-voice, document analysis and observation. Data generated were analysed following emergent themes that were used to answer the research questions. Findings revealed that the university started enrolling students with visual impairments in 2004 and has since established a Disability Resource Centre which is equipped with assistive devices and is manned by caring staff. Findings revealed a glaring absence of a university policy on inclusion. The guiding principles used did not clearly articulate issues of inclusion. The students’ positive experiences resulted from single rooms allocated to them and the support received from friends and caring staff. Negative experiences emanated from bureaucratic admission procedures, challenges of adjusting to university life in the absence of orientation and mobility training, financial challenges, hostile social environment and the students’ perceptions of themselves. The students suggested that the university should assist them with fees and expressed their wish to be consulted on matters that concern them. They xviii also suggested close co-operation between the administration and the Disability Resource Centre. The conclusion reached was that although the university was sensitive to issues of inclusion, there were still some deficiencies in the system that were impacting negatively on the inclusion of students with visual impairments. The study recommended a framework which shows the different committees and support systems which can be formed at different levels to facilitate the development of a comprehensive policy on inclusion and expedite its implementation. The involvement of students with visual impairments in the different committees was also recommended. This would afford them the chance to exercise their agentic resources and be involved in matters which concern them, rather than rely on decisions made by sighted individuals who might not possess adequate knowledge of what visual impairment entails.
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- Date Issued: 2016
A framework to evaluate user experience of end user application security features
- Authors: Shava, Fungai Bhunu
- Date: 2016
- Subjects: User interfaces (Computer systems) -- Design Web sites -- Design
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12951 , vital:27137
- Description: The use of technology in society moved from satisfying the technical needs of users to giving a lasting user experience while interacting with the technology. The continuous technological advancements have led to a diversity of emerging security concerns. It is necessary to balance security issues with user interaction. As such, designers have adapted to this reality by practising user centred design during product development to cater for the experiential needs of user - product interaction. These User Centred Design best practices and standards ensure that security features are incorporated within End User Programs (EUP). The primary function of EUP is not security, and interaction with security features while performing a program related task does present the end user with an extra burden. Evaluation mechanisms exist to enumerate the performance of the EUP and the user’s experience of the product interaction. Security evaluation standards focus on the program code security as well as on security functionalities of programs designed for security. However, little attention has been paid to evaluating user experience of functionalities offered by embedded security features. A qualitative case study research using problem based and design science research approaches was used to address the lack of criteria to evaluate user experience with embedded security features. User study findings reflect poor user experience with EUP security features, mainly as a result of low awareness of their existence, their location and sometimes even of their importance. From the literature review of the information security and user experience domains and the user study survey findings, four components of the framework were identified, namely: end user characteristics, information security, user experience and end user program security features characteristics. This thesis focuses on developing a framework that can be used to evaluate the user experience of interacting with end user program security features. The framework was designed following the design science research method and was reviewed by peers and experts for its suitability to address the problem. Subject experts in the fields of information security and human computer interaction were engaged, as the research is multidisciplinary. This thesis contributes to the body of knowledge on information security and on user experience elements of human computer interaction security regarding how to evaluate user experience of embedded InfoSec features. The research adds uniquely to the literature in the area of Human Computer Interaction Security evaluation and measurement in general, and is specific to end user program security features. The proposed metrics for evaluating UX of interacting with EUP security features were used to propose intervention to influence UX in an academic setup. The framework, besides presenting UX evaluation strategies for EUP security features, also presents a platform for further academic research on human factors of information security. The impact can be evaluated by assessing security behaviour, and successful security breaches, as well as user experience of interaction with end user programs.
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- Date Issued: 2016
A morphogenic and laminated system explanation of position-practice systems and professional development training in mainstreaming education for sustainable development in African universities
- Authors: Agbedahin, Adesuwa Vanessa
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/584 , vital:19972
- Description: This research focuses on Education for Sustainable Development (ESD) in Higher Education Institutions (HEIs), particularly in Africa. It explores the roles and practices of these institutions, especially their professionals, in the Anthropocene era where increasing concern for contemporary environmental and sustainability issues and risks emerge. The study presents a longitudinal case study of institutions and participants of the Swedish/African/Asian International Training Programme (ITP) on ESD in Higher Education (HE), who are mostly university educators. This thesis however focuses on African ITP participants only. At a macro level, the research sought to examine how African university educators have contributed to the United Nations Decade of Education for Sustainable Development (UNDESD) through their participation in the ITP (which is a change oriented professional development training programme on ESD) and the associated ESD ‘change projects’. The change projects are ITP participants’ direct attempts to mainstream environment and sustainability issues, concerns, and concepts into core university functions and practices: teaching, research, community engagement, and management operations and policy engagement. At a meso level the study sought insight into how educators in national institutions were supported by sub-regional and regional initiatives, institutions and organisations, including the Mainstreaming of Environment and Sustainability in African (MESA) Universities Partnership programme, especially an initiative supported by the Southern African Development Community Regional Environmental Education Programme to provide (limited) seed funding to three southern African universities to establish what are known as ‘MESA Chairs’, with dedicated time and support for MESA activities in their universities . At a micro level, this research sought to investigate how the position-practice systems and the ITP shape (enable or constrain) effective ESD mainstreaming in higher education, and how the morphogenetic approach and laminated system can be used to understand and explain these dynamics and their relations with meso and macro level engagements. The research sought to understand these dynamics through empirical investigations using survey questionnaires, interviews, document analysis and field visits. The research is constituted as theoretical, conceptual, methodological and analytical exploration using a singular and nested case study research approach, underlaboured by a critical realist ontology, and drawing on a social learning epistemology and social realist morphogenetic interpretive lens. In particular, ontological depth was sought via critical realist laminated system explanation. See Chapter Two for details. This study was carried out in three phases. Phase one encapsulates the investigation of all ITP ESD in higher education alumni who were Asian and African participants from the inception of the ITP to its completion, over a six-year period (2008-2013). This included 280 academics from Asia and Africa in 35 countries in Asia and Africa from 106 institutions in Asia and Africa with their 139 change projects. The outcome of phase one of the research is only included in this thesis as an appendix (see Appendix 3; Agbedahin & Lotz-Sisitka, 2015). However, this phase provided and formed the foundational data that was expanded in phases two and three for the purpose of this study. Phase two of this research concentrated on a less broad population of research participants comprising only all African ITP alumni, from all regions in Africa. The overall data collection and analysis included 162 academics in 23 African countries from 66 institutions with their 81 change projects. The aim was to investigate and provide a morphogenetic explanation of their change projects and how the relationship between participants’ positions and practices (and that of others) may influence ESD mainstreaming in universities. The outcome of this phase two investigation is presented in Chapter Four. In phase three, (nested) case studies of Swaziland, Zambia, and Botswana (in the southern Africa region), which included all the ESD ITP HE participants therein and the three corresponding EE/ESD MESA Chairs, were developed. The population sample in this phase three therefore contained 20 academics, from six institutions with their nine change projects. This phase was characterised by field trips to these countries and in-depth data collection and analysis in order to investigate and deepen the morphogenetic explanations of their change projects and how the relationship between participants’ positions and practices (and that of others) have indeed influenced the ESD mainstreaming in universities. The outcome of this phase three research is presented in Chapters Five, Six and Seven. The final Chapter Eight of this thesis focuses on the seven scalar laminated system perspective and reflections on this research and discussion of these perspectives for supporting the mainstreaming of ESD in African higher education institutions and more specifically in the three case countries and respective institutions presented in Chapters Five, Six, and Seven. The seven scalar laminated system is presented in relation to the position-practice system, and draws on morphogenetic social realist and social learning theory to provide perspective on the actual change processes. Chapter Eight also includes a discussion on social learning and its implication for ESD mainstreaming, and provides recommendations for further research. The outcome of the theoretical exploration underpinning this study provided a potential model for understanding ESD learning and change processes that are facilitated by professional development training programmes in the context of ESD in HE. This study also provides a model for appraising educational changes in time and in space, especially in relation to ESD, or the types of changes that can be brought about by professional development interventions such as those provided by the ITP and how they can be tracked, monitored and documented. For the field of professional or academic development in higher education, this research highlights the significance of the relationship between position-practice systems, professional development interventions and institutional transformation. For the field of ESD in higher education, this study shows the need for in-depth consideration of the position-practice system and sphere of influence of change agents and related stakeholders in and around their institutions in the design and development of professional development programmes. It further sheds light on the laminated system of factors that contextually constrain and/or enable effective ESD mainstreaming at individual, collective, institutional, national, regional and global levels.
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- Date Issued: 2016
A narrative-discursive analysis of abortion decision-making in Zimbabwe
- Authors: Chiweshe, Malvern Tatenda
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/496 , vital:19964
- Description: Most research on abortion decision-making has looked at the factors or influences that are seen to affect abortion decision-making and thus take a health determinants approach. However, this approach is rarely able to account for the complex, multi-faceted nature of abortion decision-making, and it is often not located within a framework that can unpick the complex array of power relations that underpins the process of abortion decision-making. Research on abortion decision-making has rarely examined how women who undergo a termination of pregnancy (TOP) construct micro-narratives of the decision to terminate the pregnancy and also how these women are positioned by the service providers who interact with them. Using a Foucauldian postcolonial feminist approach and narrative-discursive analysis, this study explores abortion decision-making narratives in a Zimbabwean context where abortion laws are restrictive. In this study I elicited the narratives of women who had undergone an abortion about how they came to make the decision and proceeded to terminate the pregnancy. I highlight the discourses employed in constructing these narratives and how women position themselves in these narratives and discourses. These are then compared to the subject positions enabled in health service providers’ narratives on the same topic. These narratives are then linked to the social discourses and power relations that work to enable or constrain reproductive justice. The data were collected from three sites in Harare, Zimbabwe. The three sites were Harare Hospital, Epworth and Mufakose. An adapted version of Wengraf’s (2001) narrative interview was used to elicit narratives from 18 women who had terminated pregnancies (six at each site). Semi-structured interviews were conducted with six service providers (two nurses at Harare Hospital, two village health workers in Epworth and two nurses in Mufakose). All the service providers interviewed have experience working with women who have terminated pregnancies. In narrating their stories about their abortions, the women employed discursive resources around shame, stigma, religion, health and culture. These discursive resources were drawn upon in the construction of the women’s micro-narratives. The women spoke in a socially sanctioned manner where stories were enabled and constrained by particular religious, cultural and gendered discursive resources. In these stories, cultural constructions, gendered understandings of motherhood and femininity constrained reproductive justice for women who have terminated pregnancies. Comparisons of the way women positioned themselves and how they were positioned by health service providers point to the existence of social discourses and power relations that work to constrain reproductive justice. While the women saw themselves as having ‘unsupportable pregnancies’, the service providers positioned them as being evil, selfish and irresponsible. The negative positions deployed by the service providers point to the vilification and blaming of women who have undergone a termination of pregnancy. In these positions, the woman is at fault and there is silence on the role of men in abortion decision-making. In the women’s narratives and the health service providers positioning of the women a ‘reproductive rights’ discourse was absent. This was significant as much of the activism around abortion has centred on the woman’s rights to her body. Where rights were mentioned, it was in reference to foetal rights (using cultural, moralistic religious understandings of abortion as killing). The missing ‘reproductive rights’ discourse points to a need to move from a reproductive rights framework to a reproductive justice framework that can be applied through local understandings of hunhu/ubuntu. By doing this, abortion is not seen as a ‘choice’ that a woman makes but rather as involving broader social and environmental circumstances that make a pregnancy ‘unsupportable’.
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- Date Issued: 2016
Adaptations in allopatric populations of Triakis megalopterus isolated by the Benguela Current: steps towards understanding evolutionary processes affecting regional biodiversity
- Authors: Soekoe, Michelle
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5389 , http://hdl.handle.net/10962/d1021264
- Description: This study was initiated to gain a better understanding of evolution and adaptation of elasmobranchs by investigating how a putative biogeographic barrier, the Benguela Current, had influenced populations of a demersal shark species, Triakis megalopterus. It was hypothesized that the Benguela Current formed a biogeographic barrier in the distribution of T. megalopterus and was responsible for the divergence between South African (SA) and Angolan (AN) populations. Since elasmobranchs are generally characterized by a slow rate of evolutionary change and conservative morphology and life history traits, it was hypothesized that there would be limited genetic, morphological and life history divergence between the populations. Both mtDNA Control Region (mtCR) and microsatellites (nDNA) were used to assess population connectivity and structure of T. megalopterus. The mtCR predominantly showed a northern (Angola, AN, and Namibia, NA) versus southern (Western Cape, WC, and Eastern Cape, EC) Benguela subsystem arrangement. This suggested that the formation of the Benguela Current had an influence on the genetic structure of T. megalopterus during the early Pleistocene. The nDNA, however, showed a distinct transoceanic, Atlantic (AN, NA, WC) versus Indian Ocean (EC) arrangement, and this was attributed to the more recent exposure of the Agulhas Bank and reduced rocky shore habitat during the glaciations of the late Pleistocene. Traditional morphological analyses on full body and tooth morphology were used to assess phenotypic plasticity and/or adaptability of T. megalopterus. A novel method of geometric morphology, with potential for non-lethal application, was developed and tested to examine interpopulation divergence in shape. Traditional morphometrics showed significant divergence between populations and this variation was congruous with the mtCR haplotypes. However, the divergence in the truss variables was not concomitant to the haplotypes and suggested that differences in shape may be attributed to phenotypic plasticity. There was limited divergence in the tooth morphology between populations. The divergence in several morphological characters associated with swimming speed and manoeuvrability may be attributed to both habitat structure and dominant prey in the different biogeographic zones. The diet of T. megalopterus consisted primarily of crustaceans, teleosts and molluscs. The significant variation in the diet between populations suggested a generalist tooth configuration and broad trophic adaptability. There was significant divergence in the interpopulation life history parameters. The AN population had the fastest growth, smallest size at maturity, and shortest longevity. Individuals in the EC population had the youngest age at maturity, while the WC population had the earliest parturition. This divergence may be attributed to the contrasting thermal regimes in the three biogeographic regions and the dissimilar exploitation rates of the three populations. The results of this thesis demonstrated that a combination of the formation of the Benguela Current and sea level change most likely contributed to vicariance of three populations of T. megalopterus. The significant interpopulation morphological and life history divergence appeared to be both phenotypic and genetic, and suggested that contrasting environmental drivers can result in relatively rapid change in elasmobranchs.
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- Date Issued: 2016
Addressing gender-based violence in the age of Aids: rural youth engaging peers through social media
- Authors: Geldenhuys, Martha Maria
- Date: 2016
- Subjects: AIDS (Disease) in adolescence -- South Africa -- KwaZulu-Natal -- Attitudes , Violence -- Sex differences , Digital storytelling , Social media -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12469 , vital:27069
- Description: This study responds to the following research question: How might rural school youth engage peers using social media in a participatory cultures framework to contribute to addressing gender-based violence in their community? This question is supported by the following secondary questions: How do rural school youth understand gender-based violence in their community. how might rural school youth use social media within a participatory cultures framework to engage peers in addressing GBV How can rural school youth engage with their peers via social media to facilitate youth agency in a participatory cultures framework This qualitative study is positioned in a critical paradigm and employs a visual participatory research methodology to contribute to addressing gender-based violence in the age of HIV and AIDS. The participants in this study are five learners (3 boys and 2 girls) with five of their peers (3 boys and 2 girls) from a secondary school in rural Vulindlela in KwaZulu-Natal, purposively selected from Grade 9 classes. Digital storytelling was employed as the main visual method of data generation to express the participants’ understanding of, and solutions to, genderbased violence. The stories were used by the participants to engage their peers around the topic via social media and to enable them to reflect on their own agency. The study draws on Jenkins’ theory of participatory cultures as a heoretical framework. Thematic analysis was applied to make meaning of the findings. The findings show that rural school youth understand gender-based violence (GBV) as a complex problem. Youthful learners are able to competently apply social media to address GBV and engage their peers through social media – hifting the power to participate as agents of change.The findings have implications for youth, the school, and the community. The youth are seen as knowledgeable actors who should inform intervention programmes aimed at social change. Social media can offer an engaging environment for peer learning and support. For digital participation, the youth need to acquire digital skills at school which could be integrated throughout the curriculum, drawing on participatory cultures. In the community, youth as knowledge producers are competent in leading, guiding, and instructing community members using social media spaces as more people have access to inexpensive digital technology that allows them to participate in community intervention programmes aimed at social change. I conclude by arguing that youth can express lived realties on GBV and solutions to GBV through visual methods such as digital storytelling. Their engagement on social media such as Facebook can be viewed as intervention by assuming agency through a guided process of solving community problems collaboratively with peers through the process of participatory cultures. This democratic process strengthens agency for community benefit and highlights a new youth and peer culture where youth circulate new and self-made content aimed at social action through their continuous reflection – a shift in power as the voices and actions of youth are acknowledged.
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- Date Issued: 2016
Against all odds: the effect of electoral violence on the political participation of citizens: a case study of voters in Nairobi
- Authors: Plata, Stephanie
- Date: 2016
- Subjects: Elections -- Kenya -- Nairobi , Political participation -- Kenya -- Nairobi , Political violence -- Kenya -- Nairobi
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5589 , vital:20913
- Description: Competitive national elections can play a significant role in the consolidation process of developing and established democracies alike. Nevertheless, if not handled adequately, they have the potential to bring long-existing, existential conflict lines to the surface. This electoral conflict, becoming manifest in election violence, has the potential to shy people off from voting and negatively affect their attitude towards elections and democracy in general. The present study examined the ways in which violent electoral conflict affected the political participation and the personal attitudes towards democracy of ordinary Kenyan citizens. Kenya has experienced violent electoral conflict repeatedly since the re-introduction of competitive elections in 1992 and became one of its prime examples due to the devastating 2008 post-election clashes. In order to answer the research questions, 32 semi-structured interviews with 34 victims of electoral violence coming from four main ‘hotspot areas’ of the 2008 post-election violence as well as four expert interviews were conducted. The study finds that the experience of violent electoral conflict led to diametrically opposed reactions in the behaviour of political participation among respondents. About two-thirds of them indicated a change in their behaviour of political participation. With 33% of the respondents found to be “participating more”, this group even outnumbers its “participating less” counterpart (30%). This finding is rather surprising as the experience of electoral violence is usually associated with the tendency to shy off from political participation, not only in Kenya. Based on their attitudinal dispositions towards democracy in general and towards democracy in Kenya more specifically, as well as towards Kenyan elections, politics and politicians, a fourfold typology of Kenyan citizens was developed from the sample. It includes: the voting citizen, the resigned citizen, the passive citizen, and the active citizen. The voting citizen with no further interest in politics or political participation was found to be the most prevalent type of citizen in the sample. Attention needs to be taken towards the resigned citizen, which could, in case of further violent electoral conflict and the continuing marginalization of specific ethnic groups, cause a threat to the stabilization process of Kenya’s democracy. Contributions of this study were in designing a destination identity framework as well as in discovering the identity of the city of Nelson Mandela Bay. Directions for future studies include the possibility to conduct a qualitative study on place identity so as to obtain a more nuanced understanding of sub-identities in the city.
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- Date Issued: 2016
An assessment of the role of guidance and counselling in promoting learner discipline in secondary schools in the Oshikoto region of Namibia : a case study of learners with discipline problems
- Authors: Mbongo, Emelia Ndapandula
- Date: 2016
- Subjects: Educational counselling -- Namibia Counseling in secondary education -- Namibia School discipline -- Namibia School violence -- Namibia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2325 , vital:27753
- Description: The study assessed the role of guidance and counselling in promoting learner discipline in secondary schools in the Oshikoto region of Namibia. The study used the mixed methods approach, which resulted in providing qualitative and quantitative data to provide an understanding of the problem. The instruments for data collection were questionnaires for principals, teachers, teacher counsellors and learners, as well as one-on-one interviews with learners. Thirty-one (31) principals, ninety-eight (98) teachers, thirty-seven (37) teacher counsellors and four hundred and eighty-nine (489) learners participated in the study. Results from the questionnaires were analysed by using descriptive statistics in the form of frequencies and percentages. Data presentation took the form of tables and bar graphs. Qualitative data collected from interviews were transcribed and put into themes and categories. The study revealed that schools experienced a wide range of disciplinary problems. It was further revealed that learners are affected by issues emanating from the environment, namely, schools and societies which influence their behaviour negatively. The principals and teachers believe that exclusionary and punitive methods are effective in managing learner indiscipline, while teacher counsellors and learners were against the use of such methods. In addition, principals, teachers and teacher counsellors all have a major role to play in maintaining discipline in schools through guidance and counselling. Suggestions were thus made to strengthen the use of guidance and counselling in promoting learner discipline in secondary schools by: improving training for teacher counsellors/Life Skills teachers in guidance and counselling, sensitisation of school managers about the roles and responsibilities of teacher counsellors, including the role played by teacher counsellors in learner discipline, improved leadership from school principals, strengthening the co-ordination and communication among the school personnel, and by strengthening the referral system from teachers to teacher counsellors and from teacher counsellors to outside agencies. It was recommended that the use of guidance and counselling in promoting learner discipline would be strengthened if teacher counsellors’ training is improved, school principals are sensitised on the roles of teacher counsellors, including their role in learner discipline as well as improved co-ordination and communication among school personnel regarding learner discipline. The study further recommended that the referral system of learners experiencing problems from teachers to teacher counsellors and from teacher counsellors to outside agencies should be strengthened.
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- Date Issued: 2016
An assessment of the role of leadership in the successful implementation of performance management : a case of the Eastern Cape district municipalities
- Authors: Dweba, Zandisile Moses
- Date: 2016
- Subjects: Municipal government -- South Africa -- Eastern Cape Public administration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/12183 , vital:39194
- Description: At the core of this study is the quest to understand the role leaders play in the successful implementation of performance management in the Eastern Cape municipalities, in the Republic of South Africa. Among the triggers for the study, was the Auditor-General’s lamentation that leaders did not set the correct tone by implementing sound performance management processes, evaluating and monitoring performance in the South African municipalities. He attributed this failure, inter alia, to the lack of employees’ and leadership commitment to the sound implementation of performance management. In an attempt to gain a deeper understanding and possibly respond to the Auditor-Generals’ concern, the researcher sought: To assess the role of leadership and ascertain the extent to which the identified leadership roles were demonstrated in the successful implementation of performance management in the Eastern Cape District Municipalities. Following a review of literature and the conducting of a mixed-methods, empirical study, numerous revelations and findings were made, among which were that, the literature on the leadership-performance link continued to be fragmented and lacking in uniformly defining the concepts, let alone the link between leadership and performance. Because of the multi-dimensionality and the multi-faceted nature of the leadership concept, there still existed a need for more detailed studies on the nature of the leadership-performance link. The eight roles of innovator, broker, producer, director, coordinator, monitor, facilitator and mentor suggested by Quinn, do not provide an exhaustive list of roles, although they provide a starting point on which leader capacitation could be anchored. Whilst the respondents had overwhelmingly affirmed that leaders played the requisite roles in their municipalities, concerns were expressed on deficient leadership competence, poor screening of new leadership entrants, and party political allegiance which was perceived to, at times, cloud their roles. Following a review of literature and past research, numerous studies were uncovered, on the leadership-performance link, which appeared to need consolidation, synthesis and refinement, with a view to sifting and isolating areas that might be of benefit to the implementation of performance management in the Eastern Cape municipalities.
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- Date Issued: 2016
An ethnographic study of beginner mathematics teachers’ classroom practices in the first three years of their employment: Shaping of a Professional Identity
- Authors: Narayanan, Ajayagosh Ettappiriparambil
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2069 , http://hdl.handle.net/10962/d1020967
- Description: The main theme in this study examines how beginner mathematics teachers (BTs) shape their professional identity in their first three years of classroom practices in Lesotho. This study, which focuses particularly on BTs’ second and third year of employment, gathers data with an understanding that the notion of professional identity is multi-faceted. Professional identity embraces a host of other identities such as personal identity, teacher identity, mathematics identity and community of practice identity. This study is framed by social theories of learning. Learning occurs by active participation and practice. BTs’ peripheral participation assists them in making sense of the activities (situated learning) in which they are engaged, in the classrooms. The sense making processes eventually shape their professional identity. In line with situated meanings that BTs form, the key notion (professional identity) is further categorised into personal identity, teacher identity, mathematics identity and community of practice identity. These identities integrate to become the professional identity of a beginner mathematics teacher. Using a narrative ethnographic approach as the research method, I have made use of extensive classroom observations and interviews to gather data. In this study, six volunteer participant BTs were originally selected. These teachers were from two districts, Berea and Maseru in Lesotho. After being observed in the classrooms, these teachers were interviewed. In the third year of the study, one participant withdrew from the study. I used vertical (descriptive) analysis to narrate their classroom practice followed by horizontal analysis to understand how they shape their professional identity. The analytical model enables the researcher to analyse the data in order to establish how the BTs’ actions, their reflexive stories and their journey in becoming a mathematics teacher shape their professional identity. The recurring themes that emerged from the horizontal analysis are the ways BTs approach the classroom practice which is dominated by teacher-centred learning. This involves demonstrating an example and then students following this model to practice more examples. In this sense, their approach is the same though these BTs started understanding how their classroom approaches can bring changes in the learning of mathematics. I analysed the utterances from the BTs’ classroom activities by separating these into mathematizing and subjectifying. The subjectifying utterances were further analysed to understand how these created meaning. These, in my view, are also central features of a teacher’s practice that need interpretation in order to understand the shaping of a professional identity. The key finding is that their narrative helped them to understand how they shape their professional identity. The study highlights the importance of listening to BTs’ stories of how they become mathematics teachers. Their narratives can be the benchmark for stake-holders, policy makers and potential researchers as the study on BTs’ professional identity is relatively new in Lesotho.
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- Date Issued: 2016
An evaluation of sampling and statistical methods for long-term monitoring of subtidal reef fishes : a case study of Tsitsikamma National Park marine protected area
- Authors: Parker, Denham
- Date: 2016
- Subjects: Reef fishes -- South Africa -- Monitoring , Tsitsikamma National Park (South Africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5385 , http://hdl.handle.net/10962/d1019991
- Description: Tsitsikamma National Park (TNP) possesses the oldest (established 1954), and one of the largest (350 km2) ‘no-take’ marine protected areas (MPA) in South Africa. A long-term monitoring (LTM) programme to observe the subtidal reef fishes in the TNP MPA was established in 2007. To date, 243 angling replicates have been completed, and a total of 2,751 fish belonging to 41 different species have been caught and released. In an era of unprecedented global biodiversity loss, data that can be used to monitor ecosystems and gauge changes in biodiversity through time are essential. This thesis aims to improve the methodological and statistical processes currently available for LTM of subtidal reef fish by providing an evaluation of the TNP MPA LTM programme. Angling data revealed definitive spatial structuring, in the form of spatial autocorrelation, and a shift in viewing spatial dependency as a statistical obstacle to a source of ecological information created a new avenue of data inference. Species-specific distribution maps identified localized habitat as the main predictor variable for species abundance, emphasizing the need for accurate a priori bathymetric information for subtidal monitoring. ‘Random forest’ analyses confirmed spatial variables are more important than temporal variables in predicting species abundance. The effectiveness of Generalized Linear Mixed Models (GAMMs) to account for spatial autocorrelation was highlighted, and evidence that disregarding spatial dependencies in temporal analyses can produce erroneous results was illustrated in the case of dageraad (Chrysoblephus cristiceps). Correlograms indicated that the current sampling strategy produced spatially redundant data and the sampling unit size (150 m2) could be doubled to optimize sampling. Temporal analyses demonstrated that after 50 years of ‘no take’ protection the TNP MPA ichthyofauna exhibits a high level of stability. Species-specific size structure was also found to be highly stable. Dageraad was the only species to exhibit a definitive temporal trend in their size structure, which was attributed to recruitment variation and the possibility that large individuals may migrate out of the study area. The inadequacy of angling as a method for monitoring a broad spectrum of the fish species was highlighted, particularly due to its selectivity towards large predators. As a result, a new sampling technique known as Stereo Baited Remote Underwater Videos (stereo-BRUVs) was introduced to the LTM programme in 2013. Stereo-BRUVs enabled sampling of 2640 fish belonging to 52 different species, from 57 samples collected in less than two years. A comparison of the sampling methods concluded that, compared to angling, stereo-BRUVs provide a superior technique that can survey a significantly larger proportion of the ichthyofauna with minimal length-selectivity biases. In addition, stereo-BRUVs possess a higher statistical power to detect changes in population abundance. However, a potential bias in the form of ‘hyperstability’ in sites with unusually high fish densities was identified as a possible flaw when using stereo-BRUVs. In an attempt to provide a more rigorous method evaluation, simulation testing was employed to assess the ability of angling and stereo-BRUVs to accurately describe a decreasing population. The advantage of this approach is that the simulated population abundances are known, so that each sampling method can be tested in terms of how well it tracks known abundance trends. The study established that stereo- BRUVs provided more accurate data when describing a distinct population decline of roman (Chrysoblephus laticeps) over 10- and 20-year periods. In addition, spawner-biomass was found to be a more accurate population estimate than relative abundance estimates (CPUE and MaxN) due to the inclusion of population size structure information, highlighting the importance of length-frequency data. The study illustrated that an evaluation framework that utilizes simulation testing has the potential to optimize LTM sampling procedures by addressing a number of methodological questions. This includes developing a procedure that aligns data collected from different sampling methods by applying correction factors, thus ensuring LTM programmes are able to adapt sampling strategies without losing data continuity.
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- Date Issued: 2016
An exploration of challenges in leadership development within Eskom's distribution division operating unit : a case-study of Limpopo Province
- Authors: Mashau, Mbangiseni Adam
- Date: 2016
- Subjects: Eskom (Firm) Leadership -- South Africa Government business enterprises -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8198 , vital:31965
- Description: Although the issue of leadership is a sensitive subject especially when dealt with it in the context of State Owned Entities operations, avoiding the need to highlight the seriousness of plights and challenges hampering adequate development of current and prospective leaders may be regarded as an act of ignorance. It is certainly better to have the knowledge and not use it than to want to use critical information but you do not have it at all. As South Africans, we are currently more than lucky to be living in the democratic era where a thirst and hunger of knowledge is entirely one’s choice. The South African communities and Sate Owned Enterprises leaders deserve to be informed about issues regarding the performance of these entities in order for them to partake positively. State Owned Entities are undoubtedly the face of the country and consequently, their leadership is expected to play exemplary role of the highest order because their acts and/or omissions may not go unnoticed. Although all State Owned Entities are essential, Eskom is known to be the blood and oxygen for the country’s competitiveness and driving force behind the economy. Adequate leadership development within Eskom’s Limpopo Operating Unit can only positively impact on the major operations in the province and the country in particular. Although Eskom Distribution Division is found throughout South Africa, Limpopo province was selected to be a case to be studied. The study used a qualitative research methodology with the aim of eliciting narrated data from participants. Through this research methodology, a focus group approach was applied in order to narrow down the scope of the study. The study revealed that factors such as lack of self-confidence, fear of possible positional take-over by new comers, lack of succession planning and failure to implement the contents of Individual Development Plans are amongst a barrage of hindrances of adequate leadership development in the Business Unit. Despite the fact that the aforementioned impediments are seemingly known by the Business Unit’s senior management, it has also been revealed that officials are obscured by the need to focus on results whilst neglecting development of human capital. Due to the critical role that is played by Eskom in the country, the study has potential of positively contributing to the body of knowledge, other SOEs and professional practices in general.
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- Date Issued: 2016
An exploration of how consistently and precisely mathematics teachers code-switch in multilingual classrooms
- Authors: Chikiwa, Clemence
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2076 , http://hdl.handle.net/10962/d1021304
- Description: Many education research studies conducted in and outside South Africa encourage teachers to take advantage of the presence of multilingualism in their classrooms and to use it to the advancement of students’ conceptual learning. This study adopts the notion that code switching is a potential resource that teachers can use when teaching multilingual mathematics classes. The aim of this study is to determine how precisely and consistently selected teachers of multilingual mathematics classes code switched during teaching of trigonometry and geometry at secondary school. This study is informed by socio-cultural theory in general and Vygotsky’s work in particular. It focussed specifically on the critical role that language plays in the teaching and cognitive development of mathematics. My study situated within an interpretivist paradigm, used a case study research design and a mixed method research approach. Data were obtained through document collection, observing and interviewing three Grade 11 Mathematics teachers purposively selected from three secondary schools in Grahamstown and King Williamstown education districts of the Eastern Cape Province, South Africa. Data were quantitatively and qualitatively analysed. Findings from this study revealed that the frequency of code switching was not consistent across teachers, topics and lessons. Teachers taught predominantly in the public domain exposing students to compromised mathematical content through their code switching practices. Borrowing code switching was prevalently employed consistently across the participating teachers. Very little transparent code switching, from mainly those mathematical terms commonly used in the foundation and the intermediate phases, was evident in teacher language. No Grade 11 trigonometry and geometry terms in isiXhosa were transparently and consistently code switched. The data suggested that while precision was observed in some cases, it was not consistent. Inconsistencies were caused by lack of planning for code switching, lack of teaching materials in indigenous languages, selective code switching, and ‘safe mode’ code switching strategies which affected teachers’ pedagogical practices. Overall results in this study illustrate that the lack of planning for code switching and the lack of explicit policies and clear-cut official positions on code switching for teaching has contributed to inconsistent and imprecise code switching by the participating teachers. This study concludes that the development of supporting mechanisms, identifying and documenting best practices to encourage transparent, meaningful and beneficial code switching is urgently required to aid and promote conceptual understanding of strongly bounded sub-registers of secondary school mathematics such as trigonometry and geometry. It is anticipated that this study will contribute significantly to the ongoing debate on language use in education and to the institution of best practices for judicious, consistent and precise use of students’ home language during the teaching of mathematics in South Africa.
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- Date Issued: 2016
An investigation into the public policy making role of the judiciary :The case of South Africa
- Authors: Maluleke, Life Reuben
- Date: 2016
- Subjects: Policy sciences -- South Africa Political planning -- South Africa Public opinion -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9812 , vital:35005
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- Date Issued: 2016
An investigation into the survival strategies of the rural elderly in Zimbabwe: a case study of Hobodo ward in Mangwe District in Zimbabwe
- Authors: Marazi, Tafara
- Date: 2016
- Subjects: Rural elderly -- Zimbabwe , Elderly poor -- Zimbabwe , Ophans -- Services for -- Zimbabwe , AIDS (Disease) -- Zimbabwe , Child welfare -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3407 , http://hdl.handle.net/10962/d1020605
- Description: The thesis focuses on the survival mechanisms of the rural poor elderly in Zimbabwe. The situation of the rural elderly is looked at in the context of the ravaging HIV/AIDS pandemic. The focus is specifically directed on the increasing numbers of orphans who are generated following the rampant deaths of their parents (sexually active individuals). With Africa failing to effectively withstand the forcefulness of the pandemic, the community structures in Zimbabwe are being heavily shaken to the detriment of all social groups. It is within this continuum that the research is laid out to investigate the situation on the ground. In this case, a fieldwork exercise was carried out in the Hobodo ward of Mangwe district in Zimbabwe. An intensive and in-depth examination of the critical situation was pursued under the case study model. To make the study more focused, the elderly were placed under investigation with regards to their new role of providing familial care for the orphans. The manner in which they face such a towering task under strained resources and limited knowhow was explored. The well-being of the orphans was also investigated in close relation to the welfare efforts of the elderly guardians. The investigations were made in respect of the contribution of the local resources towards the innovativeness of the elderly guardians. The adaptivity of the elderly and the versatility of the orphans were examined within the confines of the social and the economic capitals of the Hobodo ward. It is within the natural, social and economic capital dimensions of the Hobodo rural locality that the applicability of the sustainable livelihoods framework in explaining the dire social situation of the elderly and the orphans was brought under spotlight. The study was pursued through the qualitative research paradigm. This was done to capture the social perceptions, beliefs and the innovative capabilities of the elderly in their natural environment; and under the fieldwork setting. Several data collection techniques were employed to unveil the subject under study. These included interviews, questionnaires, participant observations, focus group discussions. Sampling was used to produce the research framework. Participants in the research were largely identified through random sampling. In special circumstances, purposive sampling was used. Tape recording and note taking were largely used to capture the responses of the research participants.
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- Date Issued: 2016
An investigation of the morphological and electrochemical properties of spinel cathode oxide materials used in li-ion batteries
- Authors: Snyders, Charmelle
- Date: 2016
- Subjects: Lithium ion batteries Cathodes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12929 , vital:27135
- Description: Li-ion batteries have become the more dominant battery type used in portable electronic devices such as cell phones, computers and more recently their application in full electric vehicles (EV). Li-ion batteries have many advantages over the traditional rechargeable systems (Pb-acid and Ni-MH) such as their higher energy density, low self-discharge, long capacity cycle life and relatively maintenance free. Due to their commercial advantages, a lot of research is done in developing new novel Li-ion electrode materials, improving existing ones and to reduce manufacturing costs in order to make them more cost effective in their applications. This study looked at the cathode material chemistry that has a typical spinel manganese oxide (LiMn2O4) type structure. For comparison the study also considered the influence of doping the phase with various metals such as Al, Mg, Co and Ni that were made as precursors using various carboxylic acids (Citric, Ascorbic, Succinic and Poly-acrylic acid) from a sol-gel process. Traditional batch methods of synthesizing the electrode material is costly and do not necessarily provide optimized electrochemical performance. Alternative continuous less energy intensive methods would help reduce the costs of the preparation of the electrode materials. This study investigated the influence of two synthesis techniques on the materials physical and electrochemical characteristics. These synthesis methods included the use of a typical batch sol-gel method and the continuous spray-drying technique. The spinel materials were prepared and characterized by Powder X-Ray Diffraction (PXRD) to confirm the formation of various phases during the synthesis process. In addition, in-situ PXRD techniques were used to track the phase changes that occurred in the typical batch synthesis process from a sol-gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis (TGA), whereby the materials decomposition mechanisms were observed as the precursor was gradually heated to the final oxide. These synthesized materials prepared under various conditions were then used to build suitable Li-ion coin type of cells, whereby their electrochemical properties were tested by simple capacity tests and electrochemical impedance spectroscopy (EIS). EIS measurements were done on the built cells with the various materials at various charge voltages. TG analysis showed that the materials underwent multiple decomposition steps upon heating for the doped lithium manganese oxides, whereas the undoped oxide showed only a single decomposition step. The results showed that all the materials achieved their weight loss below 400 °C, and that the final spinel oxide had already formed. The in-situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and then finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4, and LiCo1.09Mn0.91O4). For other materials, the precursor would start as an amorphous phase, and then upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4 and LiNi0.5Mn1.5O4). The in-situ study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C. Hence the results implied that a type of sintering of the particles would occur at temperatures above 600 °C, thereby increasing the respective crystallite size. The study showed that the cathode active materials made by the sol-gel spray-drying method would give a material that had a significantly larger surface area and a smaller crystallite size when compared to the materials made by the batch process. The electrochemical analysis showed that there was only a slight increase in the discharge capacities of the cells made with the spray-drying technique when compared to the cells made with the materials from the batch sol-gel technique. Whereas, the EIS study showed that there were distinct differences in the charging behavior of the cells made with the various materials using different synthesis techniques. The EIS results showed that there was a general decrease in the cells charge transfer resistance (Rct) as the charge potential increased regardless of the synthesis method used for the various materials. The results also showed that the lithium-ion diffusion coefficient (DLi) obtained from EIS measurements were in most of the samples higher for the cathode materials that had a larger surface area. This implied that the Li-ion could diffuse at a faster rate through the bulk material. The study concluded that by optimizing the synthesis process in terms of the careful control of the thermal parameters, the Li-ion batteries‟ cathode active material of the manganese spinel type could be optimized and be manufactured by using a continuous flow micro spray process.
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- Date Issued: 2016