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Analysis of factors affecting performance of a low-temperature Organic Rankine Cycle heat engine

  • Authors: Kalua, Tisaye Bertram
  • Date: 2017
  • Subjects: Rankine cycle Heat engineering , Cogeneration of electric power and heat
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: http://hdl.handle.net/10948/17844 , vital:28460
  • Description: Organic Rankine Cycle (ORC) heat engines convert low-grade heat to other forms of energy such as electrical and mechanical energy. They achieve this by vaporizing and expanding the organic fluid at high pressure, turning the turbine which can be employed to run an alternator or any other mechanism as desired. Conventional Rankine Cycles operate with steam at temperatures above 400 ℃. The broad aspect of the research focussed on the generation of electricity to cater for household needs. Solar energy would be used to heat air which would in turn heat rocks in an insulated vessel. This would act as an energy storage in form of heat from which a heat transfer fluid would collect heat to supply the ORC heat engine for the generation of electricity. The objective of the research was to optimize power output of the ORC heat engine operating at temperatures between 25℃ at the condenser and 90 to 150℃ at the heat source. This was achieved by analysis of thermal energy, mechanical power, electrical power and physical parameters in connection with flow rate of working fluid and heat transfer fluids.
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  • Date Issued: 2017

Analysis of the reliability for the 132/66/22 KV distribution network within ESKOM’s Eastern Cape operating unit

  • Authors: Pantshwa, Athini
  • Date: 2017
  • Subjects: Electric power distribution Electricity -- Supply -- Engineering , Smart power grids
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: http://hdl.handle.net/10948/19750 , vital:28953
  • Description: A stable and reliable electrical power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, utilities must strive and ensure that the customer’s reliability requirements are met and that the regulators requirements are satisfied at the lowest possible cost. It is known fact around the world that 90% of the customer service interruptions are caused due to failure in distribution system. Therefore, it is worth considering reliability assessments as it provides an opportunity to incorporate the cost or losses incurred by the utilities customer as a result of power failure. This must be considered in the planning and operating practices. The system modelling and simulation study is carried out on one of the district’s distribution system which consists of 132 kV, 66 kV and 22 kV network in Aliwal North Sector ECOU. The reliability assessment is done on the 22, 66 and 132 kV system to assess the performance of the present system and also predictive reliability analysis for the future system considering load growth and system expansion. The alternative which gives low SAIDI, SAIFI and minimum breakeven costs is being assessed and considered. The reliability of 132 kV system could be further improved by constructing a new 132 kV line from a different source of supply and connecting with line coming from another district (reserve) at reasonable break even cost. The decision base could be further improved by having Aliwal North Sector context interruption cost. However, the historical data which may be used in Aliwal North Sector to acquire interruption costs from the customers are being proposed. The focus should be on improving the power quality on constrained networks first, then the reliability. Therefore for the Aliwal North power system network it is imperative that Eskom invest on the reliability of this network. This dissertation also analysed load reflected economic benefit versus performance expectations that should be optimized through achieving a balance between network performance (SAIDI) improvement, and total life cycle cost (to Eskom as well as the economy). Reliability analysis conducted in this dissertation used Aliwal North power system network as a case study; the results proved that the system is vulnerable to faults, planned and unplanned outages. Reliability evaluation studies were conducted on the system using DigSilent software in conjunction with FME. These two models gave accurate results with acceptable variance in most indices except for the ENS where the variance was quite significant. It can be concluded that DigSilent results are the most accurate results in all three reliability evaluation scenarios for the Aliwal North Power System, best interpretation being that of DigSilent.
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  • Date Issued: 2017

Ant colony optimisation-based algorithms for optical burst switching networks

  • Authors: Gravett, Andrew Scott , Gibbon, Timothy B
  • Date: 2017
  • Subjects: Distributed algorithms , Ants -- Behavior -- Mathematical models
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/18939 , vital:28757
  • Description: This research developed two novel distributed algorithms inspired by Ant Colony Optimisation (ACO) for a solution to the problem of dynamic Routing and Wavelength Assignment (RWA) with wavelength continuity constraint in Optical Burst Switching (OBS) networks utilising both the traditional International Telecommunication Union (ITU) Fixed Grid Wavelength Division Multiplexing (WDM) and Flexible Spectrum scenarios. The growing demand for more bandwidth in optical networks require more efficient utilisation of available optical resources. OBS is a promising optical switching technique for the improved utilisation of optical network resources over the current optical circuit switching technique. The development of newer technologies has introduced higher rate transmissions and various modulation formats, however, introducing these technologies into the traditional ITU Fixed Grid does not efficiently utilise the available bandwidth. Flexible Spectrum is a promising approach offering a solution to the problem of improving bandwidth utilisation, which comes with a potential cost. Transmissions have the potential for impairment with respect to the increased traffic and lack of large channel spacing. Proposed routing algorithms should be aware of the linear and non-linear Physical Layer Impairments (PLIs) in order to operate closer to optimum performance. The OBS resource reservation protocol does not cater for the loss of transmissions, Burst Control Packets (BCPs) included, due to physical layer impairments. The protocol was adapted for use in Flexible Spectrum. Investigation of the use of a route and wavelength combination, from source to destination node pair, for the RWA process was proposed for ACO-based approaches to enforce the establishment and use of complete paths for greedy exploitation in Flexible Spectrum was conducted. The routing tuple for the RWA process is the tight coupling of a route and wavelength in combination intended to promote the greedy exploitation of successful paths for transmission requests. The application of the routing tuples differs from traditional ACO-based approaches and prompted the investigation of new pheromone calculation equations. The two novel proposed approaches were tested and experiments conducted comparing with and against existing algorithms (a simple greedy and an ACO-based algorithm) in a traditional ITU Fixed Grid and Flexible Spectrum scenario on three different network topologies. The proposed Flexible Spectrum Ant Colony (FSAC) approach had a markably improved performance over the existing algorithms in the ITU Fixed Grid WDM and Flexible Spectrum scenarios, while Upper Confidence Bound Routing and Wavelength Assignment (UCBRWA) algorithm was able to perform well in the traditional ITU Fixed Grid WDM scenario, but underperformed in the Flexible Spectrum scenario. The results show that the distributed ACO-based FSAC algorithm significantly improved the burst transmission success probability, providing a good solution in the Flexible Spectrum network environment undergoing transmission impairments.
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  • Date Issued: 2017

Anthropometric indicators in identifying malnutrition risk among children younger than two years in Motherwell, Nelson Mandela Metropolitan Municipality

  • Authors: McLaren, Shawn William
  • Date: 2017
  • Subjects: Nutrition disorders in children -- South Africa -- Nelson Mandela Bay Municipality , Malnutrition in children -- South Africa -- Nelson Mandela Bay Municipality
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/19256 , vital:28811
  • Description: Introduction: South Africa is burdened with a high prevalence of childhood malnutrition. The World Health Organisation (WHO) endorses weight for length (WFL) Z-scores and mid-upper arm circumference (MUAC) as tools for identifying children who are malnourished. The MUAC measurement offers many advantages for its use in community nutrition, and may aid in the early identification of malnourished children. More accurate and comprehensive data on child anthropometric status are needed in the Nelson Mandela Bay Health District (NMBHD), as well as assessment of the efficacy of using a simplified tool such as MUAC to screen for malnutrition. Aim: This study aimed to synthesise a profile of the nutritional status of children younger than two years old in Motherwell, Nelson Mandela Metropolitan Municipality (NMMM) to assess the value of MUAC as a predictor of malnutrition risk and develop malnutrition screening recommendations relevant to this population. Methods: This study followed a cross-sectional design using a quantitative approach. A convenience sample (n=419) of children below 24 months of age was selected from clinics and creches in Motherwell between October 2015 and February 2016 (Ethics approval: H15-HEA-DIET-002). Primary caregivers provided informed written consent for study participation. Trained fieldworkers performed anthropometric measurements according to standardised methods and completed a structured questionnaire. Data was described using means and standard deviations. Linear regression was used to assess relationships within the data. The MUAC’s ability to identify malnutrition was described using sensitivity and specificity probabilities. Results: Only 6% of the sample of children (n=23) were classified as stunted and 3% of the children (n=12) were severely stunted. The WHZ Z-score identified 0% (n=1) child with severe acute malnutrition (SAM), and 1% (n=3) children as MAM. The MUAC identified more children as SAM (2%) and MAM (3%). It was found that 16% of the children (n=65) were overweight or obese according to WHZ. It was found that there is a strong linear relationship between WHZ and MUAC (r=0.739). Using the least squares regression equation, a MUAC cut off value of 13,80cm for males and 13,5cm for females between six and 24 months old was projected. The male cut-off value has a 100% sensitivity and 94,5% specificity for MAM and SAM while the female MUAC cut off had a specificity of 96,4%. Low birth weight children had significantly (p<0.0005) lower mean WAZ and HAZ scores than normal birth weight children. Conclusions and recommendations The prevalence of overweight and obesity among children younger than two years was high in Motherwell, while stunting and wasting prevalence were lower than expected for the population. Raising the MUAC cut-off values from 12,5cm for MAM to 13,80cm for males and 13,47cm for females may increase the number of children younger than two years who are included in nutrition interventions. It is recommended that healthcare workers focus on breastfeeding and appropriate complementary feeding practices to reduce the risk of overweight in infants and young children.
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Anti-fetishism: parodying the depiction of the female body as fetish

  • Authors: Pirie, René Alexis
  • Date: 2017
  • Subjects: Body image -- Social aspects Fashion -- Social aspects
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: http://hdl.handle.net/10948/20377 , vital:29272
  • Description: sexual objectification of women is widespread in contemporary lifestyle and fashion magazines. Models used for advertising purposes often set a standard of beauty and youth that is unrealistic and limiting. This standard has damaging effects on women’s sense of self and their societal behaviour. Such images not only sexualise as well as fetishise women’s bodies, but also encourage self-surveillance. This research study examines Cindy Sherman, Sarah Lucas, Louise Bourgeois and Ángela Burón’s artistic responses to fetishized images of women, in order to assess what artistic strategies could be used to oppose such images in magazine advertisements. It aims to identify what anti-fetishism involves in theory and practice and to use this information to formulate an anti-fetish strategy which informs a series of anti-fetish artworks. The purpose of this series of works is to oppose the fetishization of women, particularly in magazine advertisements of high-end consumer products. The study contributes to the discourse of anti-fetishism and addresses a knowledge gap since research on anti-fetishism has much room for development. It is a Qualitative research study which adhered to a Practice-based research method. The key findings of this study are that anti-fetishism and female fetishism are approaches that differ from one another yet also overlap. Furthermore, Anti-fetishism involves the use of parodic mockery, while female fetishism is concerned mostly with undecidability as a strategy. From the examination of the artists, the anti-fetishistic strategy of parody, largely influenced the practical component of this research study. Parody offers a clear opposition to the still widespread fetishization of women in magazines both in South Africa and other Westernized countries across the world.
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  • Date Issued: 2017

Antibacterial activities of both combined and individual medicinal plants extracts traditionally used to treat pneumonia

  • Authors: Mhango, Immaculate
  • Date: 2017
  • Subjects: Antibacterial agents , Pneumonia -- Treatment
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/19762 , vital:28959
  • Description: Pneumonia is one of the five major leading causes of death in children under-fives years and the elderly worldwide. Antibiotics used for its treatment are less potent due to bacteria development of bacteria resistant to antibiotics. This has led to a surge in search of novel drugs. There are already some drugs in clinical use that have natural products and derivatives such as quinine, morphine, vincristine, and taxol among others. The healing value of medicinal plants has been well accepted since Stone Age across the globe. This plant therapy has been prescribed and prepared independently or in combination. The following plants: Terminalia sericea, Warburgia salutaris, Dodonea angustofolia, Eucalyptus camaldulensis, Ballota africana, Kigelia africana and Acorus gramineus. These plants are most commonly used for treatment of pneumonia and other ailment, were studied to validate their antimicrobial activity based on scientific determination. The primary aim of this study was to evaluate the efficacy of these plants against bacteria pneumonia pathogens. Seven medicinal plants, independently and in combinations were relatively analysed for their antimicrobial activity against Staphylococcus aureus, Streptococcus pyogenes, and Klebsiella pneumoniae. Ground plant material of roots, bark and leafs were prepared with acetone, ethanol and distilled water. Dimethyl sulfoxide (10 &100%) was used as a reconstitution solvent and ciprofloxacin (10 %) as a positive control. The antimicrobial efficacy was determined using agar well diffusion and microtiter plate methods. Interaction between plants was evaluated by calculating fraction inhibitory concentration index (ΣFIC). Noteworthy activity for individual studies with all test organisms was observed with T. sericea. However, highest ZOI (30 mm) was observed for B. africana ethanol extract for S. pyogenes. Weak microbial activity was noted in W. salutaris and D. angustofolia extracts with all test organisms. Good antimicrobial activity was observed in combination studies with all organisms. The potency of different plant combinations varied with highest ZOI observed with B. africana and W. salutaris ranging from 33-35 mm, conversely ZOI of 35 mm was also noted for S. aureus in B. africana and E. camaldulensis ethanol extract. Noteworthy antimicrobial activity was observed in T. sericea and D. angustofolia against all test pathogens. weak antimicrobial activity with highest MICs was observed in combinations where W. salutaris was involved. After calculating ΣFICs, strongest synergistic effect was displayed for W. salutaris and D. angustofolia against all test organisms (lowest ΣFICs 0.0491). Most plant extract combinations, displayed either synergistic, additive or indifferent effect, with few demonstrating antagonistic interactions. Significant antagonism effect was noted for S. pyogenes with T. sericea ethanol extract ΣFIC value of 15.51. Based on results of this study use of plants in combination increase antimicrobial efficacy. The antimicrobial activities; synergistic and additive effects observed adds credibility in the use of plant combination for therapeutic value in treatment of pneumonia. Future studies are recommended to identify and isolate specific active compounds involved in plant combination interactions. The importance of combination studies for possible development of new antimicrobials that can succumb bacterial resistance need to be highlighted.
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  • Date Issued: 2017

Antimicrobial activity of selected plants and their combined preparations against pathogens causing respiratory infections

  • Authors: Onyebuchi, Ukwuoma Collins
  • Date: 2017
  • Subjects: Anti-infective agents , Respiratory infections -- Alternative treatment
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: http://hdl.handle.net/10948/21197 , vital:29455
  • Description: Bacterial infection of the respiratory system is one of the leading causes of death in the world’s population, killing over four million people annually. Treatment of respiratory infections is usually by antibiotics administration. The emergence of multi-drug-resistant pathogens has led to the search for more effective therapeutic agents especially from medicinal plants, as compounds from plants have been shown to possess some therapeutic potential. The aim of this study is to determine the antimicrobial activity of three plants, Tetradenia riparia, Leonotis leonurus and Salvia africana-lutea and the activity of their various combined preparations against 27 pathogens usually associated with respiratory ailments. Various solvents were used for extraction of the dried powdered plant materials. The agar disc diffusion antimicrobial assay and the micro-dilution assay methods were used to determine the inhibitory activity and the minimum inhibitory concentration of the plant extracts. The nature of phytochemicals present in the extracts was determined by thin layer chromatography. The results obtained in this study, showed that ethanol produced the highest average extract yield in both the individual and combined plant preparations. A two-way analysis of variance for the disc diffusion assay showed no significant difference in the inhibition zones (Appendix 1 and 2). MIC of 0.8 mg/ml was obtained with S. africana-lutea against S. pneumoniae ATCC 49619 and B. cereus ATCC 10976 strains, indicating a strong antibacterial activity. Synergistic interaction (FIC index ranging from 0.20 – 0.50) and a strong antimicrobial activity (MIC values ranging from 0.4 – 0.8 mg/ml), was obtained with the acetone extract of the 1:1 combination of L. leonurus with S. africana-lutea. The XEA and CEF solvent systems eluted the most number of compound spots and produced the best separations. The results obtained in this study validate the traditional use of these plants and their combinations for the treatment of respiratory ailments.
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  • Date Issued: 2017

Application of the theory of critical distance technique to predict fracture toughness in friction stir welded Ti-6Al-4V sheet

  • Authors: Rall, William Henry
  • Date: 2017
  • Subjects: Friction stir welding Fracture mechanics
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/20351 , vital:29266
  • Description: With modern day socioeconomic pressures to deliver more cost effective, higher performance and energy efficient mechanisms and structures, light weight design is coming more to the forefront of design methodologies. These methodologies need to apply lightweight materials in unison with a defect tolerant design strategy. Titanium is certainly not a new material and was used in large quantities in the 1960’s and ‘70s, but mostly in military applications. The main drawback of this material was cost, however due to current design needs as mentioned the consumption of the material is rising rapidly. Friction stir welding is by no means a new technique anymore, however, relatively speaking it is still in its infancy when compared to other traditional welding techniques. It has been applied mostly to low melting temperature metals, more specifically aluminium; however, its application to higher melting temperatures has started to enjoy more attention over the last few years. The lower temperatures at which the weld occurs, when compared to conventional processes, is the main reason for applying this technique to materials melting at a higher temperature such as titanium. Fracture mechanics allows modern-day designers and maintenance engineers to operate structures with an inherent flaw. These flaws may be due to geometric features of the design; fabrication defects or defects such as cracks that have developed over time within an operational structure. Fracture mechanics has evolved significantly since Griffith first proposed it in the early 20th century. The application of the method is often complex and determining the material properties for fracture resistance can be problematic and costly. Many techniques have been proposed over time to simplify the application of this method and one of these techniques would be the theory of critical distance. Since the technique is relatively new and has mostly been applied to more brittle materials, this study aimed not only to apply this technique to a more ductile material but additionally to one that is classified as a sheet material. The initial tests of this study investigated if a common convergent point could be determined by using three notches varying in size. The technique does not have a standard that governs its application. The initial tests did not yield a common intersecting point thus a second study was applied to see if sample width would influence the results. The results from the study indicated that wider samples seemed to yield similar apparent fracture toughness results, however a common convergence point could still not be established. This prompted a more in-depth study which involved various sample widths coupled with varying notch depths. Sharper notches were also applied and samples with controlled cracks were also tested. The results clearly showed that as the plastic zone size increases in relation to the ligament length of the sample, the critical distance becomes larger. The results also suggested that it would perhaps be best to use sample sizes with notches which allow fracture of the sample before the nett section stress reaches the material’s yield strength. The final tests involved testing the friction stir welded material. Various other studies were also done to corroborate the fracture toughness results. The stress relieved samples showed a reduction in the fracture toughness due to possible precipitation hardening during the stress relieving heat treatment process. The welded material showed an increase in the apparent fracture toughness when compared to the parent plate. The results indicate that residual stresses have an influence on the fracture toughness. In terms of the critical distance, it would appear that the value stays unchanged from the parent plate to the welded material; however, what is significant was that the value seemed to stay more or less constant as long as the nett section stress of the notched samples stayed below the yield stress of the material.
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  • Date Issued: 2017

Appointment and promotion disputes in the public education sector

  • Authors: Rustin, Jonavon Keith
  • Date: 2017
  • Subjects: Labor disputes -- South Africa Education -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: http://hdl.handle.net/10948/20277 , vital:29182
  • Description: Promotions and appointments in the Public Education Sector had led to many disputes that were referred to the Education Labour Relations Council (the "ELRC"). For a long time most disputes referred to the ELRC concerned promotion disputes. In this treatise the applicable law relating to the promotions and appointments is described and evaluated. Shortly before the completion of the treatise a collective agreement was concluded under the auspices of the ELRC with a view to regulating appointments and promotions. The historical background is traced and the present legislative framework is explained. Thereafter the ELRC Resolutions dealing with the topic discussed and the new collective agreement is unpacked.
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  • Date Issued: 2017

Assessing cultural readiness for lean implementation at an automotive component manufacturer in Port Elizabeth

  • Authors: Levendal, Arend Randolph Dimitre
  • Date: 2017
  • Subjects: Organizational effectiveness Organizational change , Corporate culture Motor industry -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10948/18145 , vital:28580
  • Description: Automotive component manufacturers face significant competitive challenges in the global market and are constantly looking for means to improve their competitive advantage. Organisations then often acquire lean tools as an attractive option to achieve this. Research has however highlighted that the underlying “Lean Culture” is what is really necessary for organisations to achieve and maintain a competitive advantage. According to Rother (2010) lean implementation can be seen as a project or an initiation of an on- going development process where learning is taking place. This implementation implies a change in organisational culture from its existing state to a state where it reflects a lean culture. The literature review into Lean highlights the importance of establishing a Lean Culture. This research relied on an existing Lean Culture Causal Framework to assess cultural readiness for lean implementation at an automotive component manufacturer in Port Elizabeth (Company X). This was done utilising an empirical study which relied on an existing questionnaire associated with the said Lean Culture Causal Frame work. This Framework focuses on four broad categories of leadership actions; Awareness, Engagement, Consistency and Accountability.
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  • Date Issued: 2017

Assessing talent management at Passenger Rail Agency of South Africa (PRASA)

  • Authors: Khanyezi, Thembani Hopewell
  • Date: 2017
  • Subjects: Personnel management Employee retention , Incentives in industry Performance -- Management
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10948/17680 , vital:28429
  • Description: There is no question that effective talent management implementation requires a well-defined process. Talent management includes all talent management systems that are required to optimise the workforce within an organisation. The talent management system includes: talent planning, acquiring talent, developing talent, managing talent and retaining talent. Acquired talent should be developed to mould into the organisational culture so that they support the organisational objectives. The research objective of this study was to assess talent management implementation at Metrorail. To achieve this objective a comprehensive study was undertaken on Talent Management. The study involved conducting a literature review to understand the process that is necessary for talent management implementation in an organisation. An empirical study was later conducted to investigate whether the processes of talent management have been successfully implemented at Metrorail. The survey was compared to the literature review to establish whether the findings from Metrorail agreed or disagreed with the literature reviewed. As much as the empirical results showed a case of progress towards Employee Empowerment, Employee Engagement and Talent Retention, there were areas of concern with regard to Recruitment, Compensation and Rewards, Performance Management as well as Organisational Culture.
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  • Date Issued: 2017

Assessing the innovation capability of South African SMEs in pursuing export opportunities

  • Authors: Mbele, Lindokuhle Peter
  • Date: 2017
  • Subjects: New business enterprises -- Management Technological innovations Economic aspects
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10948/44443 , vital:37811
  • Description: Innovation is broadly perceived as an important competitive enabler for any business that needs to survive, stay ahead and prosper. In turbulently and unpredictable global environments, the capability of the organisation to continuously innovate is a key contributor to sustained competitiveness. Innovation capability focuses on making certain that the organisation possess appropriate strategies, structures, culture, leadership techniques and resourcing strategies to bolster effective execution of innovation activities. Innovation can only occur if the organisation has developed innovation capabilities. A number of South African SMEs continue to be reluctant to innovate and trade beyond the borders of their inherent country due to the risks which this involves. SMEs with sound innovation capabilities can make a significant contribution to a nation's competitiveness. Therefore investment in understanding an organisations innovation capabilities and the factors that contribute to successful innovation is necessary. This study assessed the innovation capabilities of South Africa SMEs and their ability to pursue export opportunities. The intention was to gain understanding on how innovation can be used by South African SMEs to improve exports opportunities. The findings revealed that only two thirds of the South African SMEs possess innovative capabilities. The observation was made that some SMEs believe that they are innovative even though they do not have innovative capabilities. Factors that contribute to improved export includes the ability to negotiate export transaction with international partners, the ability to adapt to changing export markets and the ability to meet export demands. These findings present an opportunity for SMEs to continuously assess their innovation capabilities and put measures in place to improve their innovation output and frequency. Globalisation threatens the former safe markets for local businesses, therefore for SMEs to be sustainable, grow and be competitive they should focus on creating innovative products that are marketable globally and continuously seek new markets.
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  • Date Issued: 2017

Assessing the outcomes and consequences of large carnivore reintroductions to the Eastern Cape, South Africa

  • Authors: Banasiak, Natalia Matgorzata
  • Date: 2017
  • Subjects: Carnivores -- Reintroduction , Wildlife reintroduction
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/11963 , vital:27011
  • Description: Reintroduction is a potentially powerful tool available to conservationists to cope with species population declines. Nonetheless, it is poorly understood and past reviews tend to indicate poor results. Reintroduction, under the sensu stricto IUCN definition, must have a primary objective of conservation; however species can be released to sites in their indigenous range (reintroduction sensu lato) to meet other objectives. The outcomes of these reintroductions s.l need to be assessed to determine how effectively they achieve their varied objectives. A Web of Science review revealed that only 32.1% of 131 publications on reintroduction provided clearly defined success criteria. Using economic, ecological, conservation and problem animal management objectives as reintroduction s.l. drivers, I developed context-dependent success definitions for each objective to use in reintroduction outcome assessments. These success criteria were then used to assess the reintroductions s.l. of large carnivores, namely lion, leopard, cheetah, African wild dog, spotted hyaena, and brown hyaena, to 16 private- and state-owned reserves in the Eastern Cape Province, South Africa. Ecotourism and ecological restoration were the most common objectives for the reintroduction of top predators to these reserves. Overall the reintroductions of large carnivores have been successful in meeting their objectives. Only African wild dogs have failed to establish in the province. Causes of objective-specific failures for the other species in some reserves included introductions of same-sex populations, lack of breeding events and changes in reserve management objectives. Assessments for leopard and brown hyaena were inconclusive due to lack of monitoring data. The reintroduction of large carnivores to the Eastern Cape Province has also resulted in the emergence of human-carnivore conflict on neighbouring properties. Carnivores have reportedly escaped from 8 reserves (61.5% of reserves) in the Eastern Cape. A total of 75 conflict events on 68 neighbouring properties (36.7% of neighbouring properties) have been reported. There is a major gap in research around conflict resulting from carnivore reintroductions and future research is required to fully understand the situation in the province in order to develop effective mitigation methods. An adaptive management approach to reintroductions is encouraged to improve monitoring and ensure reintroductions continue to meet their objectives. Furthermore, emerging consequences, such as human-wildlife conflict, and related mitigation strategies should be incorporated into management of reintroduced populations. Communities surrounding reintroduction sites should be educated on lifting baselines where conflict-causing species are recovering to ensure continued success of reintroduction undertakings. National management plans should be developed for all large carnivore species to improve the conservation value of small, fenced reserves that are typical of South African conservation, through a managed metapopulation approach. Management plans should include social, political, and economic factors that can influence the success of reintroductions and ultimate conservation outcomes.
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  • Date Issued: 2017

Assessment of the host properties of selected optically pure, racemic and achiral compounds

  • Authors: Jooste, Daniel Victor
  • Date: 2017
  • Subjects: Organic compounds -- Synthesis Cyclic compounds
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/18826 , vital:28735
  • Description: This study focussed on the synthesis and host properties of four different broad categories of potential host compounds, namely optically active and racemic TADDOL [(4R,5R)-α,α,α’,α’-tetraphenyl-1,3-dioxolane-4,5-dimethanol] and derivatives, TTFOL [(3R,4R)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diol], amino acid ester-derived compounds [(S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol], and compounds derived from xanthone [9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine]. The potential hosts were recrystallized from a range of possible guest species and the resulting solids analysed by 1H-NMR spectroscopy. If inclusion was observed by this technique, the complexes were analysed further using single crystal X-ray techniques and thermal experiments where possible. Competition studies were carried out where these were deemed appropriate. Optically active and racemic TADDOLs were synthesized using L-(+) and DL-(±)-tartaric acid respectively. Two further derivatives were prepared whereby the hydroxyl groups were substituted for chlorine and azide in order to assess the effect of this change on the inclusion ability. Both the optically active and racemic TADDOLs displayed similar host abilities, complexing with guests with 1:1 host:guest ratios as determined through 1H-NMR spectroscopy. Competition experiments showed that both forms of TADDOL exhibited similar guest preferences for pyridine and the methylpyridine isomers. Pyridine however was preferred over 2-methylpyridine by optically active TADDOL while the racemic form preferred this methyl-substituted guest over pyridine. Thermal analysis studies showed, surprisingly, that the TADDOL complexes containing pyridine had higher relative thermal stabilities than those containing the methylpyridines, whether the host was optically active or not. The preference order of these hosts for these guests can, therefore, not be used as a predictor for the relative thermal stability of the complexes. TTFOL was found to include only ethanol, 2-methylpyridine and dioxane from the range of guest species used; the complex with dioxane did not produce X-ray quality crystals. The L-tyrosine derivative, (S)-4-(2-amino-3-hydroxy-3,3-diphenylpropyl)phenol, was an ineffective host incapable of including any of the guests used in these experiments. The two xanthone derivatives, 9-amino-9-phenylxanthene and 1,2-bis(9-phenyl-9H-xanthen-9-yl)hydrazine each formed complexes with one guest species (morpholine and DMF, respectively).
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  • Date Issued: 2017

Benthic algal communities of shallow reefs in the Eastern Cape: availability of abalone habitat

  • Authors: Witte, Andrew Dennis
  • Date: 2017
  • Subjects: Reef ecology -- South Africa -- Eastern Cape Abalone fisheries -- Habitat -- South Africa -- Eastern Cape , Algal communities -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/12032 , vital:27021
  • Description: Marine ranching has been identified as an alternative to traditional aquacultural rearing and growing organisms for consumption. In the Eastern Cape, abalone ranching is a new and experimental industry. The aims of the research were to: first develop a GIS model to assist management in site selection for abalone seeding; and secondly to develop and standardize the sampling methodology in order to ground truth the sites, and assist in the monitoring and habitat identification of abalone. The GIS model developed in Chapter 3 was created using an unsupervised classification and fuzzy logic approach. Both vector and raster datasets were utilized to represent 7 different layers. Predominantly satellite imagery was used to classify the different substrate groups according to pixel colour signatures. The basic process was to apply a fuzzy rule set (membership) to rasters which gave an output raster (Fuzzification). The membership output rasters were overlaid which creates a single model output. It was found that model accuracy increased significantly as more layers were overlaid, due to the high variability within each of the individual layers. Model ground-truthing showed a strong and significant correlation (r2 = 0.91; p < 0.001) between the model outputs and actual site suitability based on in situ evaluation. Chapter 4 describes the investigation towards the optimal sampling methods for abalone ranching habitat assessments. Both destructive sampling methods and imagery methods were considered as methods of data collection. The study also evaluated whether quadrat and transects were going to be suitable methods to assess sites, and what size or length respectively they should be to collect the appropriate data. Transect length showed great variation according to the factor assessed. A transect of 15 metres was found to be optimal. Abalone counts showed no significant (p = 0.1) change in the Coefficent of Variance (CV) for transect lengths greater than 15m, and had a mean of 0.2 abalone per metre. Quadrat size showed a significant difference in functional group richness between quadrat sizes of 0.0625m2, and 0.25m2 but no difference between 0.25m2 and 1m2 quadrats for both scape and photographic quadrats. It was also found that between 5 and 10 replicates (p = 0.08) represents the functional groups appropriately using quadrats and that a 0.25m2 quadrat is most suitable for sampling. Chapter 5 describes the benthic community structure of Cape Recife shallow water reefs. Using the standardized methodology previously mentioned, 45 sites were assessed to identify the community structure. These sites were grouped into 5 different groups influenced by depth and substrate, as well as functional group composition according to a Wards classification. The community structure showed that depth and substrate play a significant role (p < 0.05) in the community type. There is also a significant relationship (p < 0.05) between complexity, rugosity, abalone presence and substrate. During this study the basic protocols for site selection and benthic community monitoring have been developed to support the abalone ranching initiative in the Cape Recife area. It has also provided a baseline of the benthic community in the ranching concession area which will be used as a benchmark for future monitoring efforts. The site selection, sampling, and monitoring methods developed during the course of this work have now been rolled out as Standard Operating Procedures for the ranching programme in this area.
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  • Date Issued: 2017

Buchu and Bobotie in the Boland : culinary heritage in Franschhoek, Western Cape

  • Authors: Deavin, Candace
  • Date: 2017
  • Subjects: Food habits -- South Africa -- Franschhoek -- Cross-cultural studies Plants, Edible -- South Africa -- Franschhoek
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/22254 , vital:29923
  • Description: From a confit tomato and potato tumbleweed with buchu to a cured snoek terrine rolled in wilde kruie and Cape bobotie puff pastry with blatjang, chefs that mix indigenous plants and local cuisine with European inspiration and training have proved popular in Franschhoek’s restaurants. In this boland town, the particular constructions of heritage through food, not only showcases regional flavours, but gestures towards the search for an elusive place-based ‘South African’ cuisine that is seen to be rooted in the land. Harkening back to old culinary practices and drawing from their own heritages, Franschhoek’s chefs are foraging, butchering, gathering, growing, fermenting, pickling and cooking over open fires with renewed vigour as they attempt to ground their cuisine, and indeed, themselves, in the soil around them. This thesis considers how, through the culinary repertoire of chefs in Franschhoek, food is constructed as heritage. Within this I look at what heritages are considered desirable, how food’s sensory and symbolic properties are used to their full potential, and who is behind these constructions of culinary heritage. Following on from this, I explore postcolonial and post-apartheid anxieties of place and belonging, as well as desired and emergent identities that are expressed through this culinary heritage.
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  • Date Issued: 2017

Bush clumps as indicators of thresholds of change in Arid Thicket mosaic piospheres

  • Authors: Schmidt, Anton George
  • Date: 2017
  • Subjects: Biodiversity conservation Ecological processes
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/20811 , vital:29403
  • Description: In the literature, Arid Thicket transformation by domestic meso-herbivores is purported to follow a state-and-transition model, whereby the ecosystem is initially resilient to herbivory until some threshold is crossed, where after there is a rapid shift to a new alternative stable state. My study represents a first attempt to verify this hypothesis by searching for evidence of stable ecosystem states separated by structural, functional and degradation thresholds in Pruim-Spekboomveld, a variation of Arid Thicket found in the southern Cape of South Africa. In this variation, thicket bush clumps ranging in size from approximately 1 m2 to 100 m2 are interspersed in a matrix of Succulent Karoo vegetation. I correlate structural and functional attributes of the thicket bush clumps and the soil environment beneath them (indicators of ecosystem function) to distance from artificial watering points in four piosphere treatments that have had a different rangeland management history. I mostly fit linear, exponential and sigmoid regression models to my data and use Akaike’s Information Criterion to select the best fitting model. When analysing data on changes in the variation of vegetation production with distance from water using the Normalized Difference Vegetation Index, I additionally fit Generalized Additive Models to the data to take into account more complex predicted patterns of change. Furthermore, I compare the end regions of my data in the piosphere treatments to each other and to similar data collected in a transformed and untransformed reference site. I use both the pattern and extent of transformation within and between the treatments and the reference sites, to verify the existence of stable states and structural, functional and degradation thresholds. I also subject my entire dataset to multivariate analysis using ordination and permutation procedures, in an attempt to corroborate my results from the univariate analysis and to assess the response of bush clump community composition to herbivory. My results indicate that at the scale of a bush clump, a threshold reduction in species richness, functional type diversity, succulent shrub redundancy and cover, palatable shrub cover and bush clump leaf mass below 1.5 m occurs in regions intensively used by domestic meso-herbivores. Furthermore, at the landscape scale there is a threshold reduction in canopy tree cover and bush clump density. In addition to these structural threshold changes, results from a Landscape Function Analysis indicate that soil nutrient cycling, soil water infiltration and soil stability thresholds are crossed at the landscape scale. The soil nutrient cycling threshold is affirmed by soil chemical analyses which indicate that the most rested treatment in the study area has low carbon and nitrogen levels. Furthermore, the keystone species, Portulacaria afra, is unable to re-establish itself in any of the treatments. High pH and potassium levels in all the treatments, relative to the untransformed reference site, indicate that Portulacaria afra (which prefers moderate soil conditions) is unlikely to re-establish in the study area. This finding suggests that all my treatments have crossed a degradation threshold and therefore represent an alternative stable state to the untransformed reference site. My multivariate analysis supports this finding and further indicates that the sampling zones within 25 m of the watering points in the most utilized treatments have crossed a second degradation threshold. This finding is supported by my results that indicate that structural and function thresholds (related to the size, density and ability of bush clumps to capture and retain soil resources) have been crossed. Furthermore, excessively high concentrations of base cations in these sampling zones, relative to the untransformed reference site, affirm the crossing of a degradation threshold. My results on the changes in the variation of vegetation production with distance from water using the Normalized Difference Vegetation Index, support the growing body of evidence in the literature that suggests that increases in the variance of ecosystem processes and services are important indicators of impending ecological thresholds. In general, my findings support the prediction in the literature that domestic meso-herbivore induced transformation of Arid Mosaic Thicket will follow a state-andtransition model.
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  • Date Issued: 2017

Cape gannets in contrasting environments: ehaviour, demographics and indicators of environmental change

  • Authors: Ryklief, Rabiah
  • Date: 2017
  • Subjects: Endemic birds -- South Africa Marine pollution -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/21167 , vital:29452
  • Description: Marine communities represent biological networks, where physical and chemical changes in the marine environment can influence the physiology and behaviour of marine organisms. Stochastic marine conditions can alter key biological interactions and thus, influence the mechanisms that underpin population demography and phenotypic plasticity. Marine top predators, such as seabirds, are often controlled by bottom-up processes and their ability to cope with variable ocean conditions lies in their physiological and behavioural response to such perturbations. Seabirds are central-place foragers during the breeding season making them particularly vulnerable to environmental fluctuations as they face constrains associated with reproductive effort in addition to self-maintenance. The Cape gannet Morus capensis is a medium-sized pelagic seabird that is endemic to southern Africa. The Cape gannet has experienced considerable change in population distribution and abundance over the past 50 years. These changes have been linked to a combination of fishing pressure and climate-mediated regime shifts of their preferred prey, i.e. sardine Sardinops sagax and anchovy ngraulis encrasicolus. Historically, Malgas Island was the largest Cape gannet colony in South Africa. However, it is now in a state of population decline, despite its occurrence within one of the most productive upwelling systems in the world, the Benguela Current. At present, Bird Island is the largest Cape gannet colony and has recently stabilised, despite regular immigration of gannets from the west coast. Furthermore, Bird Island lies within the Agulhas bioregion and is subject to low levels of productivity from the nutrient-poor Agulhas current. Malgas and Bird islands are the two most populous of the six extant Cape gannet colonies. Birds at these colonies provided a natural experiment due to the contrasting population trajectories and environmental conditions at their colonies. The foraging ecology and behaviour of Cape gannets were studied during the breeding season to assess the mechanistic links connecting climate and fisheries to population demography. Cape gannets displayed considerable inter-annual variation in foraging effort and distribution across a five-year period. This highlights the importance of long-term datasets to contextualise the degree of natural variation within a species, as well as considerations for conservation management. For the first time, oceanographic variables such as sea surface temperature and chlorophyll-a, indices that reflect marine productivity, were used to predict Cape gannet foraging distribution. Furthermore, Cape gannets at Bird Island had an energy budget deficit in a year when foraging effort was much higher in comparison to what was observed at Malgas Island. This in turn was linked to the first identification of nutritional stress in a Sulid species. Reasons for this include a combination of higher intra-specific competition in conjunction with a lower energetic content of referential prey species at Bird Island. Foraging effort showed more variability at Malgas Island in comparison to Bird Island, likely due to Malgas Island gannets often taking two short foraging trips a day, whereas Bird Island gannets often spent the night at sea. Some degree of phenotypic plasticity was evidenced by substantial variations across breeding seasons and ocean basins in foraging effort and behaviour.
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  • Date Issued: 2017

Challenges in distribution of old age pensions in Lesotho

  • Authors: Sejanamane, Nkhahle Daniel
  • Date: 2017
  • Subjects: Old age pensions -- Lesotho Aging -- Economic aspects -- Lesotho , Defined contribution pension plans -- Lesotho Retirement income -- Lesotho
  • Language: English
  • Type: Thesis , Masters , MPhil
  • Identifier: http://hdl.handle.net/10948/20477 , vital:29293
  • Description: The research set out to explore the nature of challenges in distribution of old age pensions in Lesotho. Poor institutional capacity failed the implementing agency, the Department of Pensions; to set up competent administrative structures to run run the pensions effectively and efficiently. A number of challenges have been identified, some of which were: inadequate supervision of the paying officers, fraud by workers and community agents, missing funds, insufficient resources, inadequate administrative capacity, overworked employees, faulty targeting, soft and discriminatory approach to non-compliance with rules and multiple use of identity documents by recipients. On the other hand, a number of opportunities have been identified to counteract the challenges. The main recommendation of the study was the engagement of mobile phone-based money transfer facilities to transfer the old age pensions from the government to the recipients. The Department of Pensions should make use of baseline database like information from civil registration agency like the Ministry of Home Affairs to confirm the validity of the pension recipients. Other recommendations included moving the division of old age pensions from the Pensions Department to the Ministry of Social Development which is the controlling body for other forms of social grants in Lesotho. The Ministry of Social Development is regarded as well equipped with qualified staff and facilities to deal with vulnerable people like the elderly.
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  • Date Issued: 2017

Characterisation of photovoltaic devices using large area light beam induced current measurements

  • Authors: Okullo, Michael , Van Dyk, Ernes , Okullo, W
  • Date: 2017
  • Subjects: Photovoltaic cells Photovoltaic power generation
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/20526 , vital:29314
  • Description: Photovoltaic (PV) modules are made by connecting PV cells in series in order to generate a reasonable voltage that can be used for any productive work. Inaccuracy in cell sorting during crystalline silicon module construction, or non-uniform deposition of PV material and laser scribing during thin _lm module construction, may introduce current mismatch in the module. Current mismatch is a consequence of connecting module cells which have non-identical electrical characteristics. When current mismatch occurs in a module, it is the cell generating the lowest current that determines the module output current and this leads to a decrease in the output power and lifespan of the module. Investigation of current uniformity and the different current reducing features in PV modules, which are potential sources of current mismatch, is therefore critical in optimising the performance of PV modules. In this study, a large area light beam induced current (LA-LBIC) measurement system was developed. This non-destructive technique was used to characterise crystalline silicon PV modules (mono-crystalline and multi-crystalline), thin _lm PV modules (amorphous silicon and copper indium diselenide) and a combined concentrator photovoltaic (CPV) module. A light source mounted onto a motorised x-y scanning stage was used to illuminate a PV module, or the Fresnel lens of a CPV module, point-by-point, while measuring the module output current. The measured current was mapped as a function of position and presented as an LBIC image. The point-illuminated circuit model of a PV module was designed and used to explain the variation in current between and within module cells in the LA-LBIC maps. Application of the model to crystalline silicon modules attributes the variation in photo-generated current between cells mainly to current mismatch between series connected cells. Current variation within cells is attributed to individual cell shunts. In the thin _lm modules, the model attributes the variation in photo-generated current mainly to differences in local cell shunts and series resistances originating from the scribing procedure during cell formation in the manufacturing process. In the PV modules studied, variation in photo-generated current was found to exist both between and within cells. The variation was more pronounced between cells than within cells. Module point I-V curves at different points of the module were measured in order to extract short circuit current, to quantify the variations between and within cells. A striation ring defect, causing a drop in short circuit current of 38%, was detected in the mono-crystalline module. Investigation of the striation ring defect indicated that the defect is active in the bulk (p-type) but inactive in the top (n-type) layer. Further characterisation of the defect revealed that a higher percentage loss in short circuit current occurs at lower light intensities. In the multi-crystalline silicon module, cracks were detected and found to electrically isolate the module cells into two parts, causing them to operate in parallel and consequently introducing current mismatch in the module. The I-V curve of the module at standard test condition (STC) revealed a step below the knee, which is a manifestation of current mismatch in the module. High currents, as a consequence of diffuse reflection, leading to multiple reflections by the top glass were also observed at localised points on the bus bar and cell separations. In the a-Si module, the variation in photo-current within some cells, was found to be substantial. In the copper indium diselenide (CIS) module, an electrical disconnection across the module cells was identified. A disconnection in the form of a triangular shape was also identified in this module, which completely disconnected the front contact of this area from the module. This unique disconnection feature caused current in the module to follow in a reverse direction when the light spot was incident within the boundary of the disconnection. Scans performed under different forward voltage biases were useful in identifying severely shunted module cells. A severely shunted cell was found to generate a higher photo-current than a good cell at the same forward bias voltage. This unique observation was explored further using point-illuminated module I-V measurements, and was found to be due to the crossing over of the I-V curves of the two cells. In order to explore the relationship between cell photo-current and cell shunt resistance, a method to determine the shunt resistances of the cells in an encapsulated module was devised. The method involves measuring the I-V curves of a fully illuminated module and a partially illuminated module when one of its cells is shaded and the I-V curves used to determine the short circuit current and the shunt resistance of the shaded cell. A strong correlation was found to exist between the short circuit current of the shaded cell and the cell shunt resistance, as well as between the short circuit current of the shaded cell and dark LBIC. The LA-LBIC technique was further applied to characterise a combine CPV module. Results showed that the Fresnel lens facets close to the centre generate a higher photo-current at the receiver than those towards the edges. The reduced photo-current towards the edges was attributed to losses due to di_raction, dielectric reflection and internal re_ection. About 65% of the area of the Fresnel lenses were found to be e_ective in light collection in terms of the photo-current generated at the receiver. Abrasions and scratches on the Fresnel lenses were identi_ed as some of the current limiting features in a CPV module. The LA-LBIC technique used in this study has demonstrated the potential to investigate current mismatch, current limiting and current enhancing features in PV modules. The capacity to further characterise current limiting features in order to investigate their effects on photo-current under different wavelengths and light intensities was also demonstrated. Extending the LA-LBIC technique to characterise a combined CPV module is a great achievement of this work.
  • Full Text:
  • Date Issued: 2017
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