A clip composition case study of communal wool production in the Eastern Cape, South Africa
- Authors: Dreyer, Susanna Maria
- Date: 2019
- Subjects: Wool industry -- South Africa -- Eastern Cape , Wool -- South Africa -- Eastern Cape Sheep industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39480 , vital:35265
- Description: Previous studies conducted on wool production in the communal areas of the Eastern Cape have concluded future research should focus on whether the observed differences in average wool price received between shearing sheds are due to differences in clip preparation (i.e. classing) or differences in the quality of the wool being produced (i.e. genetics).The objective of this study was to establish whether there are indeed geographical differences in the average wool price received by communal wool producers in the Eastern Cape and, if so, whether this difference in earnings is attributable to differences in the quality of wool produced and/or clip preparation. The current research explored eight years of wool production records of communal wool farmers (2009/10 to 2016/17) obtained from BKB, the largest wool broker in South Africa. Statistical analyses included descriptive statistics, analysis of variance, parametric tests (i.e. t-test) and multiple regression analysis. The conclusions drawn from this study are: that there are indeed statistically significant differences in the average wool price received between the different geographic areas of the Eastern Cape communal regions, and that the primary determining factor is wool quality, while clip preparation also plays an important but secondary role. The study identified specific geographic areas where developmental interventions are most critical, with specific emphasis on improving the genetic composition of the wool sheep flocks. Specific strategies are recommended, namely:Removing inferior-quality rams and replacing them with superior-quality rams to prevent any inferior nondescript rams from breeding and producing progeny; Replacing the inferior-quality nondescript ewes in specific areas with superior-quality ewes, and Improving the survival rate of lambs and thereby contributing towards expediting the rate of genetic improvement of the communal wool sheep flocks.
- Full Text:
- Date Issued: 2019
A crowdsensing method for water resource monitoring in smart communities
- Authors: Banda, Clara Mloza
- Date: 2019
- Subjects: Data collection platforms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42449 , vital:36658
- Description: Crowdsensing aims to empower a large group of individuals to collect large amounts of data using their mobile devices, with the goal of sharing the collected data. Existing crowdsensing studies do not consider all the activities and methods of the crowdsensing process and the key success factors related to the process. Nor do they investigate the profile and behaviour of potential participants. The aim of this study was to design a crowdsensing method for water resource monitoring in smart communities. This study opted for an exploratory study using the Engaged Scholarship approach, which allows the study of complex real-world problems based on the different perspectives of key stakeholders. The proposed Crowdsensing Method considers the social, technical and programme design components. The study proposes a programme design for the Crowdsensing Methodwhich is crowdsensing ReferenceFrameworkthat includes Crowdsensing Processwith key success factors and guidelines that should be considered in each phase of the process. The method also uses the Theory of Planned Behaviour (TPB) to investigate citizens’intention to participate in crowdsensing for water resource monitoring and explores their attitudes, norms and perceived behavioural control on these intentions. Understanding the profiles of potential participants can assist with designing crowdsensing systems with appropriate incentive mechanisms to achieve adequate user participation and good service quality. A survey was conducted to validate the theoretical TB model in a real-world context. Regression and correlation analyses demonstrated that the attitudes, norms and perceived behavioural control can be used to predict participants’ intention to participate in crowdsensing for water resource monitoring. The survey results assisted with the development of an Incentive Mechanism as part of the Crowdsensing Method. This mechanism incorporates recruitment and incentive policies, as well as guidelines derived from the literature review and extant system analysis. The policies, called the OverSensepolicies, provide guidance for recruitment and rewarding of participants using the popular Stackelberg technique. The policies were evaluated using simulation experiments with a data set provided by the case study, the Nelson Mandela Bay Municipality. The results of the simulation experiments illustrated that the OverSenserecruitmentpolicycan reduce the computing resources required for the recruitment of participants and that the recruitment policy performs better than random or naïve recruitment policies. The proposed Crowdsensing Method was evaluated using an ecosystem of success factors for mobile-based interventions identified in the literature and the Crowdsensing Method adhered to a majority (90%) of the success factors. This study also contributes information systems design theory by proposing several sets of guidelines for crowdsensing projects and the development of crowdsensing systems. This study fulfils an identified need to study the applicability of crowdsensing for water resource monitoring and explores how a crowdsensing method can create a smart community.
- Full Text:
- Date Issued: 2019
A deep learning approach to classifying tyres using sidewall images
- Authors: Gifford, Dean
- Date: 2019
- Subjects: Image processing -- Digital techniques , Image processing Computer science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39720 , vital:35351
- Description: End of Life Tyres (ELT's) pose a potential health and environmental risk when dumped in illegal stockpiles. For recycling to be considered feasible, a profitable business opportunity needs to be created. One method of making the recycling process of tyres more profitable is by understanding the compounds found within each tyre. This study aims at classifying these tyres in order to achieve this knowledge. A literature review was done to investigate neural networks, convolutional neural networks as well as existing deep learning architectures for image classification. A deep learning approach was applied in order to classify the logos of tyres as these approaches have proved their success in both image classification and more specifically logo classification. Although tyre classification has been implemented in the past, a deep learning approach has not been applied and the logo has not been the classifying element in any other studies. The main difference of this study compared to previous research surrounding deep learning and logo classification is the properties of the tyre logo. Logos on tyres are very similar in colour as they are purely formed in rubber and very seldom have any colour to them. Additionally, the embossed logos can contain variation among same branded tyres due to small inconsistencies in the moulds. The implementation of this deep learning solution saw multiple convolutional neural networks implemented. Some of these architectures were also implemented using transferred learning. The metrics obtained as outputs from training and testing the architectures were the accuracy, precision, recall, and F1-score. These metrics were compared in conjunction with the confusion matrix produced from testing. To ensure that variance was accounted for in the experiments, the k-fold cross-validation technique was adopted. The results of this study identified that one convolutional neural network model, MobileNet, was particularly well suited for the context of classifying logos on tyre sidewalls. The MobileNet architecture had the highest performance metrics for both training from scratch (96.7% accuracy) and transferred learning (98.8% accuracy). Three other models performed particularly well when trained from scratch, these were a modification of the LeNet architecture, ResNet50 and InceptionV3. The transferred learning results were also impressive with four out of the 5 models achieving an accuracy above 94%. Interestingly, the ResNet50 architecture failed to train when transferred learning was applied. Contrasting to this, the two models VGG16 and VGG19 failed to train when trained from scratch but performed equally as well as the other models when transferred learning was implemented. This indicates that although transferred learning can improve the performance of models, it is highly dependent on the task as well as the model. Overall the results obtained proved that a deep learning approach could be applied in order to classify tyres accurately.
- Full Text:
- Date Issued: 2019
A gatherer's paradise? Early humans and plant foraging on the cape south coast, South Africa
- Authors: Gummow, William Thomas
- Date: 2019
- Subjects: Soil amendments , Plants -- Nutrition Plant physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39687 , vital:35348
- Description: South Africa is a semi-arid country that is experiencing population growth and the associated pressure of producing sufficient crops to sustain the population. Furthermore, poor land management has also led to increased degradation of valuable arable land. To improve poor soil quality and possibly avoid or reverse degradation and ultimately desertification, it was suggested that soil amendments are a potential solution to some of these problems. Although soil amendment is a relatively well-known practice to improve soil quality, the use of rubber crumb as a soil amendment is not well studied. Rubber crumb is produced from end-of-life tyres that have been ground up to fine particles and as such can be used as a secondary resource to replace the use of virgin materials. Rubber crumb has been used in an array of industries, however, the present study investigated the possibility that rubber crumb might be used as a soil amendment to alleviate various forms of soil degradation, specifically soil compaction and crusting, and potentially improve crop establishment and growth.To determine this, a soil that is prone to crusting and compaction was amended with rubber crumb at rates of 5%, 15% and 25%. Various soil physical characteristics, such as bulk density, particle density, porosity, field capacity and penetration resistance were investigated and it was determined that as the percentage rubber crumb increases in the soil, so do the beneficial characteristics of the soil. Furthermore, the rubber crumb was also treated in various ways in order to determine how the treatments might affect the chemical properties of the soil, as well as the amount of zinc that is leached from the rubber crumb. It was found that washing the rubber with a weak acid or even water prior to adding it to the soil resulted in more desirable chemical condition compared to untreated rubber crumb. Lastly, maize (Zea mays L.) was used to determine whether amending soil with pre-treated rubber crumb in different percentages had an influence on the germination success and growth rate of maize. In terms of germination success, amending soil with rubber crumb does not seem to have a significant influence, however, growth rate decreased as the percentage rubber crumb increased, while treating the rubber with a weak acid or water prior to adding it to soil had the most positive effect on plant growth. It can therefore be concluded that rubber crumb amendment rates between 5% and 15% resulted in the most desirable soil physical properties and plant growth amongst the amendments. However the best plant growth was still seen in the control soil, to which no rubber crumb had been added.
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- Date Issued: 2019
A Statistical assessment of available solar resource across multiple sites in South Africa
- Authors: Eastwood, Kirstie
- Date: 2019
- Subjects: Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39907 , vital:35505
- Description: Around the globe, fossil fuels remain the primary source of energy at around 78% of the world’s total energy consumption. However, the associated carbon emissions, environmental impact, the depletion of fossil fuels and price and cost volatility are factors influencing the growing popularity of research into renewable energy. Solar power is acknowledged as the fastest-growing renewable energy, but the uncertainty surrounding the long-term projections of solar irradiance available for energy conversion is a hindrance when discussing the financial risk with potential investors. This study investigates the quality of freely available solar resource data in South Africa as well as proposes techniques for potential solar farm site comparisons. Tolerance intervals derived within a Bayesian framework provide information on the future available solar resource across multiple sites. These techniques capture the inherent variability in the available solar resource which equips investors with statistical methods that lead to the better understanding of the solar resource and thus aids in better decision-making.
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- Date Issued: 2019
A suitability study for the implementation of a corporate geographic information system at the King Sabata Dalindyebo Municipality
- Authors: Triegaardt, Inge
- Date: 2019
- Subjects: Geographic information systems , Information storage and retrieval systems -- Geography Information technology Sustainable development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/${Handle} , vital:37044
- Description: A tender in the Government Gazette in 2013 for the implementation of a Corporate Geographic Information System (CGIS) at the King Sabata Dalindeybo (KSD) Local Municipality, created an opportunity for a study to be conducted for the implementation of a Corporate Geographic Information System (CGIS). A CGIS is a suitable management system for implementation at a municipality, given that the municipality is ready. Internationally the implementation of CGIS at municipalities has been done successfully. In South Africa, however, the implementation of said software has been slow and at times unsuccessful. The purpose of this research study was to evaluate the current GIS knowledge and infrastructure of the KSD Local Municipality for the municipality to be a suitable candidate for the implementation of a CGIS. The evaluation was done by the collection of data through three questionnaires, two interviews and observations. The findings of this research study are discussed according to the qualitative data collected from the KSD Local Municipality and recommendations based on the results of the data collection have been made for the municipality to be implementation ready. The qualitative instruments such as pre-training, post-training/pre-implementation and postimplementation questionnaires, observations and interviews with the IT Technician and the CGIS Specialist were processed by the researcher to obtain insight to the perceptions of the employees and the current state of GIS in the KSD Local Municipality. The results from this research study were in-line with the benefits and barriers of implementation of a CGIS in municipalities in international literature.
- Full Text:
- Date Issued: 2019
A technical survey of the South African harvesting machine population
- Authors: Mathelele, Ouma Florah
- Date: 2019
- Subjects: Harvesting -- South Africa , Energy harvesting -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40999 , vital:36281
- Description: South Africa adopted the practice of conducting technical surveys from Austria three decades ago. The Austrian technical survey was used to model the South African technical survey. The survey was conducted with the aim of providing the forestry industry with a detailed analysis of the state of timber harvesting operations. The first technical survey in South Africa was conducted in 1987, and the second one in 1998. The most recent study was carried out in 2007. Since 2007, there has been no other technical survey of a similar nature conducted on harvesting and transport operations. There is no recent information quantifying the volumes harvested, identifying harvesting systems and methods used, and determining volumes harvested using these systems and methods. Furthermore, no updated information exists on the type and quantities of timber trucks transporting the volume. A fourth technical survey that quantifies and analyses these aspects in harvesting operations, therefore, was due. The fourth technical survey aimed at quantifying the number of harvesting machines and timber trucks. The survey further investigated the drivers behind the mechanisation and system preference. The four technical surveys were compared to identify trends in harvesting machines and methods. The data were collected from grower companies, harvesting and transport contractors and small-scale timber growers. Questionnaires were sent to all potential respondents from the three target groups, and interviews were later conducted with selected respondents. The harvesting machines were quantified per function i.e. felling, extraction, processing and loading. The results showed that some machines were more common compared to other machines performing the same function. Mechanised felling machines sampled had more units in the fourth survey than the previous surveys had. Of the 10.6 million m3 volume surveyed in 2017, chainsaws had 1 048 units, and their number had decreased from the 5 000 sampled in the first technical survey in 1987 that sampled about 12.8 million m3. Harvesters and feller bunchers also increased from zero in the first technical survey to 94 and 13, respectively in the fourth survey. The drivers towards the increased use of mechanised equipment were identified as safety and health, ergonomics, productivity, labour issues, operational costs, terrain, and company policies. Despite the introduction of mechanisation, however, the use of manual labour was evident in hardwood processing and loading operations. Manual debarking was more common than mechanised debarking in the fourth technical survey. When comparing all four technical surveys, the cut to length (CTL) harvesting method was dominant in hardwood; harvesting 79% of the volume sampled in the 2017 survey. The full tree method was barely applied in the first three technical surveys and in the 2007 survey, it was absent. It was only in the fourth technical survey that the method was applied, felling 27% and 9% of the sampled volumes in softwood and hardwood, respectively. The technical survey provides information to the different stakeholders in the forest industry. Such include harvesting managers and contractors, grower companies, machine distributors and researchers. The information will bring awareness to harvesting managers and contractors about the different machine options available to assist in decision making when selecting systems. Machine distributors will know the number of machines, where machines are operating and their target market. A gap in knowledge will be bridged between the different provinces regarding the different types of harvesting machines out there.
- Full Text:
- Date Issued: 2019
An assessment of the hydrologic response of the Keiskamma catchment to land use/cover changes
- Authors: Sive, Mlamla
- Date: 2019
- Subjects: Hydrological response
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44732 , vital:38165
- Description: The Keiskamma catchment has undergone significant land use/cover changes (LUCC) underpinned by land use policy reforms and climate change. However, the hydrological responses of the catchment to LUCC are not fully understood. This study sought to assess the hydrological response of the Keiskamma catchment to LUCC at catchment and hillslope scale using remote sensing, GIS, hydrological modelling and field experiments. Catchment scale assessments first involved LUCC mapping in IDRISI TerrSet software, using supervised image classification for two sets of multispectral imagery; namely Landsat Thematic Mapper (TM) of 1994 and Landsat 08 Operational Land Imager (OLI) of 2016. The LUCC maps provided an indication of LUCC over time and were prerequisite land use inputs for modelling the hydrologic response of the catchment. The Soil and Water Assessment Tool (SWAT) hydrologic model was used to model the hydrologic response of the catchment to LUCC. The Sequential Uncertainty Fitting (SUFI-2) in SWAT-CUP was used to assess model performance and uncertainty analysis. The influence of rainfall on the hydrologic response of the catchment was also assessed using linear regression. One of the prominent forms of LUCC in the Keiskamma catchment, particularly central Keiskamma is P. incana shrub encroachment. Field experiments were set up to investigate the hydrologic impacts of P. incana shrub invasion at hillslope scale, as well as to validate the results obtained by the SWAT hydrologic model. Field experiments included an assessment of the Landscape Organisation Index (LOI) of the invasion, as well as assessing of surface conditions, surface runoff (L), volumetric soil water content (cm³/cm³) and sediment loss (grams) under P. incana, grass and bare-eroded areas. High image classification accuracy assessment values of 87.2 % and 87.4 % for 1994 and 2016 respectively were obtained, with a Kappa coefficient of 0.84 for both sets of imagery. Results of the study revealed a significant increase in woody vegetation encroachment, specifically shrub invasion, forest expansion in the upper parts of the catchment, as well as an increase in exotic and invasive vegetation species within the riparian zone. The SWAT model showed a good (NSE=0.69, R²=0.69 and RSR =0.56) and unsatisfactory (NSE=0.4, R²=0.4 and RSR 0.79) model performance for calibration and validation respectively. However, for both the calibration (p-factor =0.77; r-factor 1.03) and validation (p-factor =0.92; r-factor 1.38) periods there was acceptable uncertainty as indicated by the p- and r-factor statistics. The mean annual streamflow (-71.4 %), surface runoff (-98.8 %), soil water content (-4.5 %), evapotranspiration (-5.3 %), groundwater (-79.5 %) and sediment loss (-99.9 %) decreased from 1994 to 2016. The impoundments in the catchment viz Cata, Mnyameni, Binfield, Sandile, Debe and Dimbaza dams, also contributed significantly to the streamflow reduction. A strong correlation (r= 0.61) between the declining streamflow (m3/s) and rainfall (mm) was observed. At hillslope scale, P. incana invasion was characterised by a low LOI, owing to large inter-shrub bare patches and poor soil surface conditions characterised by soil surface crusting, conducive to high runoff generation and connectivity. High surface runoff and soil losses were evident under P. incana and bare-eroded areas. Volumetric soil water content was high under grass and P. incana tussocks, intermediate in P. incana inter-patches and low in bare-eroded areas. The findings and analysis of this study conclude that the hydrologic response of the Keiskamma catchment was influenced significantly by LUCC in the form of extensive invader shrub encroachment, expansion of forestry using exotic tree species, impoundments, as well as the infestation of riparian zones by invasive vegetation. Management of woody shrub encroachment and alien invasive plants as well as indigenous forest species utilisation should be considered as amongst the key efforts towards restoring the ecohydrological integrity of the Keiskamma catchment.
- Full Text:
- Date Issued: 2019
An information extraction model for recommending the most applied case
- Authors: Padayachy, Thashen
- Date: 2019
- Subjects: Information technology , Information storage and retrieval systems System design
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43325 , vital:36794
- Description: The amount of information produced by different domains is constantly increasing. One domain that particularly produces large amounts of information is the legal domain, where information is mainly used for research purposes. However, too much time is spent by legal researchers on searching for useful information. Information is found by using special search engines or by consulting hard copies of legal literature. The main research question that this study addressed is “What techniques can be incorporated into a model that recommends the most applied case for a field of law?”. The Design Science Research (DSR) methodology was used to address the research objectives. The model developed is the theoretical contribution produced from following the DSR methodology. A case study organisation, called LexisNexis, was to help investigate the real-world problem. The initial investigation into the real-world problem revealed that too much time is spent on searching for the Most Applied Case (MAC) and no formal or automated processes were used. An analysis of an informal process followed by legal researchers enabled the identification of different concepts that could be combined to create a prescriptive model to recommend the MAC. A critical analysis of the literature was conducted to obtain a better understanding of the legal domain and the techniques that can be applied to assist with problems faced in this domain, related to information retrieval and extraction. This resulted in the creation of an IE Model based only on theory. Questionnaires were sent to experts to obtain a further understanding of the legal domain, highlight problems faced, and identify which attributes of a legal case can be used to help recommend the MAC. During the Design and Development activity of the DSR methodology, a prescriptive MAC Model for recommending the MAC was created based on findings from the literature review and questionnaires. The MAC Model consists of processes concerning: Information retrieval (IR); Information extraction (IE); Information storage; and Query-independent ranking. Analysis of IR and IE helped to identify problems experienced when processing text. Furthermore, appropriate techniques and algorithms were identified that can process legal documents and extract specific facts. The extracted facts were then further processed to allow for storage and processing by query-independent ranking algorithms. The processes incorporated into the model were then used to create a proof-of-concept prototype called the IE Prototype. The IE Prototype implements two processes called the IE process and the Database process. The IE process analyses different sections of a legal case to extract specific facts. The Database process then ensures that the extracted facts are stored in a document database for future querying purposes. The IE Prototype was evaluated using the technical risk and efficacy strategy from the Framework for Evaluation of Design Science. Both formative and summative evaluations were conducted. Formative evaluations were conducted to identify functional issues of the prototype whilst summative evaluations made use of real-world legal cases to test the prototype. Multiple experiments were conducted on legal cases, known as source cases, that resulted in facts from the source cases being extracted. For the purpose of the experiments, the term “source case” was used to distinguish between a legal case in its entirety and a legal case’s list of cases referred to. Two types of NoSQL databases were investigated for implementation namely, a graph database and a document database. Setting up the graph database required little time. However, development issues prevented the graph database from being successfully implemented in the proof-of-concept prototype. A document database was successfully implemented as an alternative for the proof-of-concept prototype. Analysis of the source cases used to evaluate the IE Prototype revealed that 96% of the source cases were categorised as being partially extracted. The results also revealed that the IE Prototype was capable of processing large amounts of source cases at a given time.
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- Date Issued: 2019
An investigation into bile formation of Wistar rats for excretion of injected gold nanoparticles
- Authors: Thole, Sagoleka Thabo
- Date: 2019
- Subjects: Nanoparticles , Nanomedicine Gold -- Immunology Bile acids -- Physiological effect
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43900 , vital:37082
- Description: There is an increase in the use of nanoparticles (NPs) throughout the world. Gold nanoparticles (AuNPs) are commonly used NPs in the field of biomedicine. NPs bigger than 8 nm are excreted via the hepatobiliary system. Bile acids (BAs) are regarded as the main components of bile. If there is a decreased or increased secretion of BAs, the composition of microbiota in the gut can change. Under normal physiological condition BAs fluctuates daily without causing any harm. Nevertheless, it is the long-term changes in bile acid secretion that can affect microbiota in the gut. If there is an increased excretion of AuNPs via hepatobiliary pathway it can alter bile formation. The aim of this study was to investigate whether the hepatobiliary excretion of AuNPs will alter the bile formation two weeks after intravenous administration of 14 nm AuNPs to Wistar rats. Rat liver samples of two previous experiments were used to investigate bile formation. The rats had been injected intravenously with a single dose of citrate capped and functionalised AuNPs. These rats were killed 14 days later. Small pieces of liver were stored in RNAlater. The mRNA of different enzymes and transporters in the hepatobiliary system were quantified in these samples and compared with suitable control. As a reference the mRNA of the same enzymes and transporters were extracted and quantified in rat liver that were killed one day after injection with one of the abovementioned functionalised AuNPs. The study shows down-regulation of genes responsible for conjugation of BAs whereas the rate-limiting enzymes were not significantly changed. This was the first study to investigate the formation of bile in relation to the use of AuNPs. The effect and consequences of AuNPs on the hepatobiliary system need further investigation.
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- Date Issued: 2019
Applications of complex functions on problems in Banach algebras
- Authors: Snyman, Jandré Dillon
- Date: 2019
- Subjects: Banach algebras , Functions of several complex variables
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48643 , vital:41055
- Description: In this dissertation, we provide applications of complex function theory to problems in Banach algebras. We discuss the structure of analytic functions f : D → A, where D is a domain of C and A is a Banach algebra as given by Aupetit in [3]: either the set {λ ∈ D : Sp(f(λ)) is finite} is of capacity zero, or there exists an integer n such that Sp(f(λ)) has exactly n elements, for every λ, except on a closed, discrete set of capacity zero, where the spectrum has at most n−1 elements. This deep result, which describes the structure of Sp(f(λ)) for all λ ∈ D, relies heavily on subharmonic techniques, which are also included in the dissertation. Let A and B be Banach algebras. A linear mapping φ : A → B is called a Jordan homomorphism if and only if φ(xy + yx) = φ(x)φ(y) + φ(y)φ(x) for every x, y ∈ A. This is equivalent to saying that φ(x 2 ) = φ(x) 2 for every x ∈ A. The following problem, due to I. Kaplansky, is still unsolved for the general Banach algebra case: Let A and B be unital Banach algebras and φ : A → B a unital, invertibility preserving linear mapping. Under what conditions of A and B is φ a Jordan homomorphism? The author’s honours project [24] served as an exposition of the GleasonKahane-Żelazko Theorem [7, Theorem 4], which provides an answer to Kaplansky’s problem in the case where B = C. In this dissertation we look at other special cases of Kaplansky’s problem, such as the case where A and B are von Neumann algberas, as solved by Aupetit [4, Theorem 1.3] and remark that his result holds for the more general case where A is any C ∗ -algebra that has the property that every self-adjoint element is the limit of a sequence of linear combinations of orthogonal idempotents in A, and B is a semi-simple Banach algebra. This result relies heavily on complex function theory, spectral theory and holomorphic functional calculus. We also provide detailed expositions of the work of Taylor [27] in which an operator calculus on undounded, closed linear operators is developed, and the work of Allan [1] in which a holomorphic functional calculus is defined for locally convex algebras.
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- Date Issued: 2019
Assessing flood vulnerability in the Nelson Mandela Bay Metro
- Authors: Zuze, Hillary
- Date: 2019
- Subjects: Floods -- South Africa -- Nelson Mandela Bay Municipality , Natural disasters Hazardous geographic environments Hazardous geographic environments -- Risk assessment , Climatic changes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44224 , vital:37135
- Description: Floods are the most frequent amongst all global natural disasters at present, causing problems such as bridge collapses, fatalities, building damages and traffic delays. Between 1995 and 2015, there were approximately 3062 global flood disasters which accounted for 56% of all declared natural disasters and these affected 2.3 billion people (almost a third of the world’s population at the time) (EMDAT, 2015). The cost of damages for this period incurred for buildings and other infrastructure was at an all-time high of R23.69 (US$1.891) trillion. It is postulated through various studies that the number of urban flood events reported is increasing significantly in comparison to the previous decades (Armah et al., 2010; Lóczy, 2013; Leaning and Guha-Sapir, 2013; EMDAT, 2015; Tanoue et al., 2016; Rogger et al., 2017). Some research has also noted an increase in the number of floods per year, which has ascended to an average of 171 in this decade, from an annual average of 127 in the previous one (Dozier, 2013; Guha Sapir et al., 2016). Sources such as the Centre of Research and Epidemiological Disasters (Guha Sapir et al., 2016) recorded that from 1995 to 2015, globally, millions of homes were vulnerable to weather-related disasters, along with 130,000 health and education facilities. During this period, urban floods accounted for 98% of houses damaged and 99.9% of education and health facilities demolished by a weather-related disaster (Davies, 2017). Flooding is particularly harmful in terms of fatalities in developing countries due to inadequate flood protection and mitigation measures (Di Baldassarre et al., 2010; Dozier, 2013). Some studies attribute the high fatalities in developing countries to the inadequate disaster management strategies implemented to counter the impacts of urban flooding (Egbinola et al., 2015; Pazzi et al., 2016; Mavhura et al., 2017). Other authors have attributed the high fatalities to the sheer number of people residing in areas prone to flooding, which has been the knock-on effect of rapidly expanding cities, overwhelmed government agencies, and a pre-existing political and social system that promotes marginalisation (Collins, 2008; Aboagye, 2012). The occupation of flood-prone areas by settlements, which is a common feature in developing countries, is the major contributor to the fatalities as it involves a degree of risk. Risk is exposure to an undesired event, in this case flooding, and contributes directly to differing levels of vulnerability (Samuels, 2018). Communities have differing perceptions of flood vulnerability because of a combination of factors. These include the magnitude of the flood experienced, the number of people or the value of assets potentially affected by flooding due to location, and the lack of socioeconomic capacity to do anything to alter their vulnerability to a disaster (Hall et al., 2005; Adger, 2006; Birkmann et al., 2013; Rogger et al., 2017). Some communities acknowledge that there are people residing in flood prone areas and take measures to reduce or eliminate the risk through social, political and economic networks. In other cases, communities are able to identify their exposure to flooding but do not have the capacity to reduce the effects (Bouchard et al., 2007; Agbaoye, 2012; Musungu et al., 2012; Siyongwana, Heijne, and Tele et al., 20155).
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- Date Issued: 2019
Assessing in-vivo clearance of colorectal cancer-targeting peptide-functionalized gold nanoparticles
- Authors: Xakaza, Hlumisa Belinda
- Date: 2019
- Subjects: Nanoparticles , Gold Nanotechnology -- Health aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44323 , vital:37153
- Description: Colorectal cancer (CRC) is a major public health problem. Gold nanoparticles (AuNPs) have been proved as a possible diagnostic tool to target CRC by peptides conjugated to gold nanoparticles (p-AuNP). According to previous reports, AuNPs accumulate in internal organs and have raised serious concerns on toxicity and safety. Understanding their fate in the body and the physiology underlying their clearance is crucial for toxicological evaluation and clinical translations. Six groups of rats were intravenously injected with a single dose of 100μg/kg body weight of citrate-capped (c.c-AuNPs), PEG-coated (PEG-AuNPs), and peptide functionalized gold nanoparticles (p.L-AuNPs, p.C-AuNPs, and p.14-AuNPs), to assess their physiologic clearance over a short-term (over sequential time-points: day 1, 3, 5, 7 and 14) and long-term period (three months). The inductively coupled optical-electron spectrometry (ICP-OES) showed accumulated c.c-AuNPs in the liver tissue. Moreover, a rapid and decreasing pattern of concentration of AuNPs was observed in urine and feces, with total excretion at day 7. Elevated levels of urine urea nitrogen (UUN) and urine creatinine (UCREA) reported an impaired kidney function for the c.c-AuNP group, while H&E staining indicated chronic progressive nephropathy (CPN) in all groups, 3 months post-injection, which is in all probability related to aging. Signs of inflammation were observed in rats treated with c.c-AuNPs, 2 weeks post-injection. The overall findings showed that the clearance of c.c-AuNPs’ clearance is compromised, which can have side-effects, while the excretion profiles of the p-AuNPs were consistent with the reducing long-term retention in the excretory organs. The p-AuNPs were found to be non-toxic and therefore show promise for CRC diagnostics and therapeutic purposes.
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- Date Issued: 2019
Block copolymer templates for metal oxide nanostructures
- Authors: Talla, Assane
- Date: 2019
- Subjects: Nanotechnology , Nanostructured materials Metal oxide semiconductors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43889 , vital:37075
- Description: Recent advances in technology have increased the need for fabrication of devices with feature sizes of tens of nanometers, such as ultra-fine filters or membranes, and high density data storage media, to name a few. For this reason, research is now focused on block copolymer nanolithographic processes, particularly the fabrication of nanoscale templates with domains well below 100 nm. Block copolymers have the tendency to self-organise into various structures, such as lamellae, spheres or cylinders on a nanometer scale. Among these possible configurations, the perpendicular cylindrical structure is most desirable, because it can be used for templates or masks for feature development, in particular, oriented wires or rods. In this work, the aim is to create a nano-mask from a di-block copolymer thin film, for zinc oxide nanorods growth. For this purpose poly (styrene-block-methylmethacrylate) (PS-b-PMMA) was investigated as a potential nano-mask. Samples were characterized using X-ray reflectometry to determine the thicknesses of the PS-b-PMMA thin films, while scanning probe microscopy and scanning electron microscopy was used to investigate the surface morphology of the samples. PS-b-PMMA thin films were produced on a random copolymer (poly (styrene-random-methylmethacrylate) (PS-r-PMMA) coated onto a silicon substrate. The PS-r-PMMA permits a non-preferential interaction between the di-block constituents and the substrate. Thermal annealing in vacuum of PS-b-PMMA on PS-r-PMMA led to perpendicular cylinders of PMMA within a PS matrix in the di-block. The typical thicknesses measured for the di-block copolymer films ranged between 33 nm and 37 nm. During this study, a perpendicular orientation of the di-block components was also produced when PS-b-PMMA was spun onto a layer of zinc oxide nanoparticles and thermally annealed in vacuum. It was shown that the ZnO nanoparticles created a corrugated surface on silicon which induced perpendicular cylinders of PMMA within the PS matrix. This was possible for a specific surface roughness parameter and film thickness. In this case, the typical thickness determined for the di-block copolymer ranged between 33 and 35 nm and the surface roughness parameter was 0.07. For the fabrication of a di-block template or PS nano-mask, the vertically oriented PMMA cylindrical nanodomains in the PS matrix were removed by exposing the film to ultraviolet radiation at an adequate dose, followed successively by washing in acetic acid and de-ionized water. It was shown that ultraviolet exposure is necessary to ensure the degradation of PMMA. A subsequent rinse in glacial acetic acid and DI water of the film exposed to ultraviolet, left an array of ordered nanoscopic pores with sizes ranging between 10 nm and 20 nm. Finally, the growth of ZnO nanorods on the di-block template produced on zinc oxide nanoparticles, was attempted using an aqueous solution based-method, namely chemical bath deposition. The rods did not grow inside the nanopores, probably due to poor capillary action. In additional experiments, the di-block template was removed by toluene (a selective solvent for PS) followed by the growth of ZnO rods on the exposed nanoparticle surface. Vertical and well separated ZnO rods formed on this surface, in places where the underlying seed layer had been attacked by the acetic acid treatment during removal of the PMMA. The observed ZnO rod morphology can be used in applications such as solar cell.
- Full Text:
- Date Issued: 2019
Bootstrap-based tolerance intervals for photovoltaic energy yield assessments
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019
Carbon and nutrient storage of the Swartkops Estuary salt marsh and seagrass habitats
- Authors: Els, Jessica
- Date: 2019
- Subjects: Estuarine ecology -- South Africa -- Swartkops River Estuary , Salt marsh ecology -- South Africa -- Swartkops River Estuary Seagrasses -- Ecology Seagrasses -- Conservation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42196 , vital:36634
- Description: Coastal wetlands play an important role in filtering nutrient contaminants from water bodies and are also effective carbon sinks. These systems are known as blue carbon ecosystems. Blue carbon is defined as the carbon stored and sequestered by coastal vegetated habitats such as seagrasses, salt marsh and mangroves. These habitats are being lost on a global scale due to climate change and other anthropogenic pressures. Quantifying ecosystem services provided by these habitats may lead to better conservation and restoration strategies. Research on this topic has escalated over the past decade but there are no published studies in South Africa. The aim of this study was to quantify the carbon, nitrogen, and phosphorus stocks in the above and below ground tissues of Zostera capensis, Spartina maritima, and Salicornia tegetaria — a seagrass, salt marsh grass, and salt marsh succulent. This was done in both summer and winter to understand the variability of carbon and nutrient storage. The organic carbon stock of the sediment beneath these three species was also quantified. Results showed that S. maritima, S. tegetaria, and Z. capensis stored 16 ± 2.9 Mg C. ha-1, 4.3 ± 0.7 Mg C. ha-1, and 2.1 ± 0.5 Mg C. ha-1 in their respective biomass, and 247 ± 48 Mg C. ha-1, 212 ± 44 Mg C. ha-1, and 224 ± 38 Mg C. ha-1 respectively in the sediment beneath these habitats. This was determined by elemental analysis and the loss on ignition method (LOI). The sediment made up the dominant carbon pool in the estuary and there was very little seasonal variation, however spatial variation was evident. The sediment carbon stocks were similar to the global mean for salt marsh (255 Mg C. ha-1) and greater than the global mean for seagrass (108 Mg C. ha-1). The Swartkops Estuary stored a total (biomass and sediment carbon combined) of 14 094 Mg C in the Z. capensis area of 62 ha, 25 286 Mg C in the S. maritima area of 96 ha, and 5 916 Mg C in the S. tegetaria, covering an area of 27 ha. This is significantly less than what has been found globally in estuaries, but this is largely due to the smaller area cover of these macrophytes. The amount of carbon stored per hectare is much larger in this South African system than in many international studies — possibly due to the high levels of pollution coming into the system. Nitrogen and phosphorus stocks in the plants fluctuated seasonally in relation to the nutrient input to the estuary, with the greatest stocks found in winter in Z. capensis, S. maritima, and S. tegetaria (0.42 ± 0.03 Mg N. ha-1, 1.6 ± 0.13 Mg N. ha-1, and 0.37 ± 0.02 Mg N. ha-1, respectively; and 0.4 ± 0.03 Mg P. ha-1, 1.2 ± 0.10 Mg P. ha-1 in Z. capensis and S. maritima respectively) because nutrient inputs to the system were highest in winter, however the P stocks in S. tegetaria were greatest in summer (0.35 ± 0.04 Mg P. ha-1). The reason for this difference is because of their ability to store phosphorus better than nitrogen and for longer periods of time due to luxury uptake. Salicornia tegetaria N and P stocks were also lower than the other two species, possibly due to its placement along the intertidal gradient, as it is not tidally inundated for as long as the other two species. The Z. capensis and S. maritima at Site 1 showed extremely high amounts of nitrogen in their tissues (105.3 ± 1.6 g kg-1 and 74.91 ± 4.1 g kg-1 respectively). This is due to the area being a depositional site as it was an old oyster farm and experiences little tidal flushing from the sea despite its proximity to the mouth. Nutrient ratios and N: biomass were determined as an indication of nutrient pollution. The N: biomass was low in both seasons in Z. capensis, S. maritima, and S. tegetaria (0.08, 0.02, 0.04 respectively) indicating consistant eutrophic conditions in the estuary. Plant biomass was a better indicator of nutrient pollution than epiphytes which were very low in the Swartkops Estuary and did not prove as a useful indicator of nutrient enrichment. These results can inform local management plans of the ecosystem service potential of these species and how they should be protected for future and current sustainable use as filters for nutrient pollution to keep the water quality in a better state. It also outlines the current state of blue carbon and nutrient stocks in an urban South African estuary.
- Full Text:
- Date Issued: 2019
Chacma baboons (papio ursinus) influence zoogeomorphic processes in the Karoo through rock movement
- Authors: Maré, Celesté
- Date: 2019
- Subjects: Geomorphology -- South Africa -- Eastern Cape , Biogeomorphology Geology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40966 , vital:36278
- Description: Animals sculpt landforms by physically altering the substrate. The field of zoogeomorphology has developed to explicitly consider the role of animals as geomorphic agents. Many digging and burrowing animals are then considered zoogeomorphic agents. While the significance of soil disturbing species is well established, geomorphic impacts are rarely quantified for rock transporting species. Chacma baboons (Papio ursinus, hereafter baboon), a widespread and abundant primate, have the potential to act as a zoogeomorphic agent through their purposeful rock displacement while foraging. With this study I assessed the role of baboons as rock rolling agents by demonstrating that baboons roll rocks to search for and feed on organisms beneath, quantifying the extent of this process, and establishing the preferences of baboons for rock features. Observations from a troop of wild baboons showed that rock rolling is an important component of the daily foraging routine of baboons, and confirmed that baboons roll rocks to feed on the organisms beneath. Baboon rock movement was extensive, with potentially tons of rock material moved across many hectares over one year in some habitats. The distance of this rock movement was influenced by a combination of rock mass, rock shape and the slope of the landscape. Baboons showed clear preferences for the rocks they rolled in terms of shape and size, with rock size being an important driver of baboon rock rolling. With this study I show that the chacma baboon is an important rock moving species, with the potential to impact a range of ecological and geological processes. As such, baboons may serve as a keystone species as they are the only species in this environment to intentionally move rocks in this way. However, because baboons are considered pests and are widely persecuted, their role in zoogeomorphic processes are vulnerable to being lost.
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- Date Issued: 2019
Comparing organic and conventional farming systems in George, South Africa
- Authors: Swanepoel, Marike
- Date: 2019
- Subjects: Organic farming -- South Africa -- George , Sustainable agriculture -- South Africa -- George Agricultural systems -- South Africa -- George
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43946 , vital:37086
- Description: This study presents some of the findings of a long-term comparative study at the Nelson Mandela University George campus which started in 2014. This research compares the differences in crop yields and soil fertility under conventional and organic farming systems. Although previous research that was conducted will be presented briefly, the main focus of this dissertation is to report on the research results generated during the 2016/17 and 2017/18 cropping seasons. The baseline study (indicator measurements) was done in 2014 and investigated soil fertility before the different farming systems were implemented. The rapid increase in human population threatens food security, especially in developing countries. Climate change together with the degradation of soil and other natural resources due to high-input industrial farming, provide further challenges in terms of agriculture and future food security. Agricultural production in South Africa faces three obstacles: water scarcity, infertile soils and poor institutional support. Therefore, regenerative and sustainable agriculture practices such as organic farming, are increasingly being promoted as an alternative to conventional farming systems in southern Africa. What is the best way of farming? This is the question every farmer is confronted with. Some say organic whilst others say conventional, but how do we determine this? What is the role of crop rotation in pest management, soil fertility and crop yield? So we set up the research to compare the two farming systems so that decisions can be based on sound scientific findings. Results showed a significant increase in the case of the organic yield in season 2016/17 for cabbage and in both seasons (2016/17 & 2017/18) for cowpea and sweet potato, proving that organic farming yields can increase over time. Soil fertility changes from the baseline year (2014) till the end of season 2017/18 were compared. Overall organic farming systems showed very promising results with higher levels of soil pH followed by a significant increase in important soil nutrients (P, K & C) compared to conventional systems. Crop rotation also had positive effects.
- Full Text:
- Date Issued: 2019
Comparison of mesozooplankton communities at three shallow seamounts in the South West Indian Ocean using size spectrum analysis
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
Critical success factors of South African construction companies
- Authors: Lombard, Daniel
- Date: 2019
- Subjects: Construction industry -- Planning -- South Africa , Construction industry -- Management Construction industry -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42229 , vital:36637
- Description: The aim of the study was to identify the driving forces of the South African construction industry for registered cidb Grade 9 companies. The next objective was to identify the critical success factors (CSF) that are required to be used by the forward-looking and pro-active cidb Grade 9 companies. The most important critical success factors were then highlighted to form a core group of CSFs for construction industry. From this core group of CSFs an attempt was then made to identify business strategies that can assist companies in gaining a competitive advantage in the construction industry of South Africa. The research was based on the problem statement from which the sub-questions and hypothesis were derived. The primary data was collected through a mixed method of quantitative and qualitative research. A ontological philosophy was used for the research to effectively collaborate with the mixed method of research used. The approach of the research was a mix of both inductive and deductive, as it pursued to identify the forces and factors dominating the construction industry. The study subsequently determined what business strategies best suit these results. The research questionnaire was distributed between senior managers of grade 9 cidb construction companies and found that the most eminent driving forces of the industry are political and government decision making, as well as economic conditions. The CSFs showed a clear indication of what the respondents perceived as the most important factors. Although there have been many advances in technology and processes over the years, the most important CSF for contractors are still the processes of bidding and tendering and the factors relating to these. The qualitative research portion of the study was an investigation on what business strategies were best related to the key driving forces and most important CSFs. Interviews were held with directors of cidb grade 9 construction companies. The themes that were identified from the analyses of the qualitative data were that business strategies relevant to differentiation, diversification, cost leadership or hybrid were seen as the most effective for construction companies. The bidding and tendering process is not merely the same process that it used to be. Frequent reviews of what the industry is going through have also become a major necessity. The research was limited to companies registered as grade 9 with the Construction Industry Development Board. The research is seen as valued as the construction industry is highly important towards the development of the economy of a country and the impact that it has on communities.
- Full Text:
- Date Issued: 2019