Showing items 221 - 240 of 1292

Your selections:

Assessing community engagement programmes to mitigate uncontrolled, deliberately ignited fires in forestry plantation-communal land interface, Kwazulu-Natal, South Africa

  • Authors: Ramantswana, Nontethelelo
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Forest fires -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52008 , vital:43439
  • Description: Forestry plantations in South Africa are surrounded by poor local communities that normally depend on the forestry resources for subsistence. This interface area is faced with human induced uncontrolled fires. There is a lack of understanding regarding the reasons for deliberate ignition of uncontrolled fires. There is also lack of information on the success of community engagement programs (CEPs) as fire protection intervention and / or their implementation barriers. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
  • Full Text: false
  • Date Issued: 2021-04

Bayesian tolerance intervals and their application to ballistic grouping consistency in competitive shooting

  • Authors: Gardiner, Marcell
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Bayesian statistical decision theory -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52456 , vital:43662
  • Description: Competitive shooting has become immensely popular since the first modern Games held in 1896. Competitive shooting remains the fastest growing segment in the firearm industry, catering to individuals of all ages. Elite shooters are capable of reaching extreme levels of precision and accuracy, despite many factors existing that affect performance in Olympic shooting. One such factor is speed variability, which is dependent on the mass of the bullet, how constant is the lead being used, and, how constant the gunpowder is. The study focusses on the Bayesian simulation method proposed by Wolfinger (1998) for determining three kinds of tolerance intervals when applied to competitive shooting data, particularly examining speed variability. These tolerance intervals included the (𝛼𝛼,𝛿𝛿) tolerance interval (where 𝛼𝛼 is the content and 𝛿𝛿 is the confidence), the 𝛼𝛼 - expectation tolerance interval (where 𝛼𝛼 is the expected coverage of the interval) and the fixed-in advance tolerance interval in which the interval is held fixed and the proportion of process measurements it contains, is estimated. Speed measurements of individual shots fired were measured with either an Oeler 35P or Magneto Speed V3 chronograph and the data was fitted to a one-way random effects model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
  • Full Text:
  • Date Issued: 2021-04

Benthic habitat mapping using marine geophysics and machine learning on the continental shelf of South Africa

  • Authors: Pillay, Talicia
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Marine geophysics
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52061 , vital:43452
  • Description: A method to map seafloor substrates using machine learning, based primarily on hydroacoustic data including multibeam bathymetry, backscatter, and side-scan sonar, has been developed. The aim was to produce a customdesigned benthic habitat classification method that digitally integrates marine geophysics and biological science data, with relevance to all elements of the local substrate, and this was the first time it was attempted in a South African context. The algorithm developed is able to produce bio-physical benthic habitat maps and this can be extended along the continental shelf of South Africa as new data setsare collected and the algorithm is supplemented. At the outset, this work has focused on broad categories of rock and detailed categories of sediment. Four study sites with varying substrate were selected to holistically build the algorithm that followed a tiered approach of machine learning: Table Bay, Clifton, Koeberg Harbour and Cape St Francis. Table Bay was used to develop a new method of physical seafloor classification, by comparing and contrasting a number of statistical algorithms and software programs. Clifton was used to test the developed clustering algorithm, and Koeberg which is 35 km to the north was used to validate the algorithm because sediment samples, along with drop camera footage, were integrated to better define the results. The resultant verified algorithm was tested at Cape St Francis, where Remotely Operated Vehicle (ROV) footage was acquired in addition to hydroacoustic data. In the first phase of the process towards developing an algorithm, a customised tool was created within ArcGIS using python scripting language to classify seafloor bathymetry, which can be applied to any area of seafloor whatsoever. The tool was based on pioneering work done by the National Oceanic and Atmospheric Administration (NOAA) on a benthic terrain modelling toolbox and adapted to include side-scan sonar data. In the second phase of work, multibeam bathymetry, backscatter and side-scan sonar data that were processed using Qimera, Fledermaus Geocoder Toolbox, and Navlog processing software, were classified using different machine learning techniques including Decision Trees, Random Forests, and k-means clustering computer algorithms. The results from these algorithms were compared to manually-digitised polygons which were created to classify the seafloor substrate distribution by identification of different textures. Integrating all results facilitated a quantitative comparison that illuminated advantages and disadvantages of each machine learning technique and ultimately the k-means clustering techniques were found to be the simplest to implement and understand and worked most efficiently based on their seafloor segmentation capabilities in Table Bay, against all three hydroacoustic data sets (multibeam bathymetry, backscatter and side-scan sonar). In the third phase of work, ground-truthed seafloor characterisation maps were produced for the two study areas of Clifton and Koeberg Harbour. This applied multibeam bathymetry and backscatter data that were collected and processed with machine learning clustering techniques. , Thesis (MSc) -- Faculty of Science, Ocean Sciences, 2021
  • Full Text: false
  • Date Issued: 2021-04

Cluster analysis for group selection in launch sales predictions

  • Authors: Watchurst, Lee
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Cluster analysis
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52003 , vital:43447
  • Description: One way for businesses to stay ahead in a competitive market is through the launch of new products and planning for these launches optimally. This includes ordering the correct quantity of stock in advance as well as maintaining these stock levels while the item launches. However, holding too much stock in warehouses can affect the business costs adversely. This research proposes the use of cluster analysis techniques to determine the up-front purchase quantity by identifying similar items and using their initial quantities sold. Products will be grouped based on their numerical and categorical attributes. Once the data is clustered, the Bass model will be used to obtain a sales profile for the new item. The Bass model is a popular choice for product life cycle planning due to the emphasis placed on the timing of adoption. The study will make use of data from a retail and wholesale company that sells, in part, single use items. With the planning for new launches being a key problem point in many companies, this research aims to optimise the planning process and ensure product launch success across stores. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
  • Full Text: false
  • Date Issued: 2021-04

Deep neural networks for robot vision in evolutionary robotics

  • Authors: Watt, Nathan
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Neural networks (Computer science)
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52100 , vital:43448
  • Description: Advances in electronics manufacturing have made robots and their sensors cheaper and more accessible. Robots can have a variety of sensors, such as touch sensors, distance sensors and cameras. A robot’s controller is the software which interprets its sensors and determines how the robot will behave. The difficulty in programming robot controllers increases with complex robots and complicated tasks, forming a barrier to deploying robots for real-world applications. Robot controllers can be automatically created with Evolutionary Robotics (ER). ER makes use of an Evolutionary Algorithm (EA) to evolve controllers to complete a particular task. Instead of manually programming controllers, an EA can evolve controllers when provided with the robot’s task. ER has been used to evolve controllers for many different kinds of robots with a variety of sensors, however the use of robots with on-board camera sensors has been limited. The nature of EAs makes evolving a controller for a camera-equipped robot particularly difficult. There are two main challenges which complicate the evolution of vision-based controllers. First, every image from a camera contains a large amount of information, and a controller needs many parameters to receive that information, however it is difficult to evolve controllers with such a large number of parameters using EAs. Second, during the process of evolution, it is necessary to evaluate the fitness of many candidate controllers. This is typically done in simulation, however creating a simulator for a camera sensor is a tedious and timeconsuming task, as building a photo-realistic simulated environment requires handcrafted 3-dimensional models, textures and lighting. Two techniques have been used in previous experiments to overcome the challenges associated with evolving vision-based controllers. Either the controller was provided with extremely low-resolution images, or a task-specific algorithm was used to preprocess the images, only providing the necessary information to the controller. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
  • Full Text: false

Deep neural networks for robot vision in evolutionary robotics

  • Authors: Watt,Nathan
  • Date: 2021-04
  • Subjects: Evolutionary robotics -- South Africa , Neural networks
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/61601 , vital:71473
  • Description: Description Advances in electronics manufacturing have made robots and their sensors cheaper and more accessible. Robots can have a variety of sensors, such as touch sensors, distance sensors and cameras. A robot’s controller is the software which interprets its sensors and determines how the robot will behave. The difficulty in programming robot controllers increases with complex robots and complicated tasks, forming a barrier to deploying robots for real-world applications. Robot controllers can be automatically created with Evolutionary Robotics (ER). ER makes use of an Evolutionary Algorithm (EA) to evolve controllers to complete a particular task. Instead of manually programming controllers, an EA can evolve controllers when provided with the robot’s task. ER has been used to evolve controllers for many different kinds of robots with a variety of sensors, however the use of robots with on-board camera sensors has been limited. The nature of EAs makes evolving a controller for a camera-equipped robot particularly difficult. There are two main challenges which complicate the evolution of vision-based controllers. First, every image from a camera contains a large amount of information, and a controller needs many parameters to receive that information, however it is difficult to evolve controllers with such a large number of parameters using EAs. Second, during the process of evolution, it is necessary to evaluate the fitness of many candidate controllers. This is typically done in simulation, however creating a simulator for a camera sensor is a tedious and timeconsuming task, as building a photo-realistic simulated environment requires handcrafted 3-dimensional models, textures and lighting. Two techniques have been used in previous experiments to overcome the challenges associated with evolving vision-based controllers. Either the controller was provided with extremely low-resolution images, or a task-specific algorithm was used to preprocess the images, only providing the necessary information to the controller. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
  • Full Text:
  • Date Issued: 2021-04

Descriptive analysis of organic farming systems and factors affecting adoption and disadoption in Zambia : a case study

  • Authors: Munthali, Robert
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic farming -- Zambia
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52111 , vital:43434
  • Description: The last 30 years since the early 1990s has seen the heightened promotion of organic farming as a sustainable farming option in Zambia. The main objectives of this research study were to carry out an analysis of organic farming systems in order to understand factors affecting adoption, as well as reasons why some organic farmers discontinue using the approach. The study involved four districts in Zambia: Mazabuka, Chikankata, Lusaka and Chongwe. Specifically, the research investigated challenges and limitations of organic agronomic practices, and analysed factors that influence adopters and disadopters of organic agriculture. Primary data were collected through interviews and by administering semi-structured questionnaires. The research population comprised approximately 250 farmers adopters and disadopters, with the sample size being 50 farmers chosen across four districts using systematic random sampling methods. Additionally, five observation research field trials were conducted in order to gather practical data on individual farmer’s crop management practices. Farmers adopting and maintaining organic methods reported several reasons for embracing the system, some of which are: organic farming is regenerative; it is environmentally responsible; it uses manure, believed to help build healthy soils rich in organic matter with better nutrient and moisture holding capacity; pesticides and synthetic fertilizers are not used, reducing the levels of toxic residues in organic products which ultimately promotes health. Labour constraints, pest and disease challenges and weed problems were some of the reasons for disadoption. Data showed that disadopters had lower education (48% had primary education), were older and with slightly more children. Although there were more women adopting organic agriculture compared to men, the difference was small 56% and 44% women and men respectively. Among disadopters there were more women (67%) compared to men (33%). Overall, the study results suggest that promotion of organic agriculture should be encouraged through liaison with government departments such as the Zambian Department of Agriculture to include organic agriculture when developing policies. In general, organic farmers have positive opinions concerning the benefits resulting from organic agriculture. Organic farmers should enjoy equal opportunities to conventional agriculture in the provision of extension services, input support, infrastructural development, access to financial resources to procure farm machinery, and equipment and most important of all, they should get fair prices for their organic produce and products. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
  • Full Text: false
  • Date Issued: 2021-04

Estimating activity patterns in camera trap studies, and the overlap between domestic and indigenous ungulates

  • Authors: Peral, Christopher Michael
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ungulates -- Behavior -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52019 , vital:43437
  • Description: Animal activity can reveal responses to social and ecological factors such as the presence of food, water, shelter, predators, competitors or conspecifics. Thus, an understanding of an animal’s activity patterns provides insights into how and why they are using landscapes in the manner in which they do. Camera trap surveys, typically used to record the occurrence of species of interest, are also an efficient way to collect data regarding animal activity patterns but require robust analytical methods. The analysis of camera trap data requires assumptions that may differ for camera trap surveys that estimate occurrence or activity. One such assumption is temporal independence. This refers to the removal of images within a specified time interval, as these images are assumed to be images of the same individual. This assumption stems from the use of-time-to-independence in occurrence or density-based studies, where it reduces overestimation of animal counts. In studies of animal activity, this assumption is generally used, even though animal behaviour or activity occurs continuously over time and as such should be measured over time. I analysed 112 467 images of eight cooccurring species, to test the effect across various times to independence, these being set at 1, 5, 10, 15, 30 and 60 minutes. Time-to-independence resulted in significant loss of data and biased the interpretation of the activity patterns of species and interactions amongst species, particularly for herbivorous social species. In light of these findings, activity pattern estimates based on camera trap studies should be cautious when using time-to-independence. I then explore ‘habitat use’ in space and time by domestic and indigenous ungulates using a camera trap survey. Domestic ungulates (livestock) have become common place on rangelands and may compete with native species. It was hypothesised that there will be overlap in habitat use by livestock and indigenous ungulates. My results show that indigenous ungulate species, particularly larger species such as kudu (Tragelaphus strepsiceros) and springbok (Antidorcas marsupialis), changed their spatial and temporal use as a result of the presence of domestic ungulates. Other smaller indigenous ungulates, such as steenbok (Raphicerus campestris) and duiker (Sylvicapra grimmia), were less affected by the presence of livestock. Kudu were found to use more open habitats at different times whilst springbok used more dense habitats at different times in the presence of livestock. This supports the hypothesis of competition between livestock and indigenous ungulates. This study provides novel insight into the analysis and interpretation of activity patterns based on camera trap surveys. Additionally, this study demonstrates the competitive displacement between domestic and indigenous ungulate species. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
  • Full Text: false
  • Date Issued: 2021-04

Estimating Bayesian tolerance intervals for a two - factor factorial model

  • Authors: Besele, Kagiso Francis
  • Date: 2021-04
  • Subjects: Gqenerha (South Africa) , Eastern Cape (South Africa) , Mathematical statistics
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52302 , vital:43587
  • Description: Quality improvement efforts have become the cornerstone of all manufacturing processes. Quality can be defined in terms of variability reduction, and since variability is a statistical concept, statistical techniques such as statistical quality control present techniques for assessing process variation. Methods such as experimental design provide a way to ascertain factor relationships and give a basis for computing variability that arises from each process variable, ultimately providing a way of calculating total process variability. This in turn results in variance components and eventually variance component estimation. As with any statistical model, estimates may be classified in any one of two ways, point estimates or interval estimates. Interval estimates that provide information about an entire population, and not only information on a few observations from a sample or knowledge about only a population parameter, are known as tolerance intervals. Wolfinger (1998) provided a Bayesian simulationbased approach for ascertaining three types of tolerance intervals using a balanced one-way random effects model. In this study, the method initially proposed by Wolfinger (1998), is extended in order to estimate tolerance intervals for the balanced two-way crossed classification random effects model with interaction. The suggested and derived techniques will be applied to the thermal impedance data initially collected by Houf and Berman (1988), and the method presented by Wolfinger (1998) will be expanded to also include the estimation of tolerance intervals for averages of observations from new or unknown measurements. This Bayesian approach provides a thorough but yet simplistic paradigm to using tolerance intervals in manufacturing settings. , Thesis (MSc) -- Faculty of Science, Statistics, 2021
  • Full Text: false
  • Date Issued: 2021-04

Estimating the population size of three large carnivore species and the diet of six large carnivore species, in Madikwe Game Reserve

  • Authors: Honiball, Terry-Lee
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Carnivores
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52139 , vital:43421
  • Description: Large carnivores play a vital role in ecosystems, providing ecosystem services such as herbivore regulation. If not properly monitored, carnivores could place significant pressure on certain prey species, and in extreme cases, result in the local extinction of certain species. A lack of demographic data can indirectly threaten carnivores, as policies and management decisions based on demographic data can result in the over harvesting or unsustainable hunting of large carnivores. Furthermore, their conservation is becoming confined to small, fenced, protected areas. Whereby species are intensively managed, making demographic and ecological data a fundamental part of conservation decisions. Therefore, it is essential for conservation practitioners to understand large carnivore demography and their role, to conserve them effectively. To provide Madikwe Game Reserve with the necessary data for effective long-term monitoring and management of the large carnivore guild, I estimated the population size of the cryptic carnivores. I then investigated the efficacy of different camera trap survey designs on improving the detection probability of leopard (Panthera pardus), brown hyaena (Parahyaena brunnea), and spotted hyaena (Crocuta crocuta). I found that brown hyaena and spotted hyaena detection probability increased with a higher number of camera traps, whereas leopard detection probability did not increase with an increased number of camera traps. I further investigated the diet, prey preferences and dietary overlap of lion (Panthera leo), cheetah (Acinonyx jubatus), African wild dog (Lycaon pictus), leopard, spotted hyaena and brown hyaena. I found that all species displayed a degree of dietary overlap, however the most notable level of competition occurred between leopards, wild dogs, and cheetahs. This iv information will assist MGR to make informed decisions about large carnivore management in the reserve. I recommend continued long-term monitoring for the establishment of trends over time, allowing for holistic management of the entire large carnivore guild. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
  • Full Text: false
  • Date Issued: 2021-04

Evolutionary robotics controllers with location perception facilitated by neural network-based simulators

  • Authors: Phillips, Antin Paul
  • Date: 2021-04
  • Subjects: Evolutionary Robots -- South Africa , Neural networks (Computer science) -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/61613 , vital:71474
  • Description: Humans impressively maintain a real-time approximation of their bodily form. For instance, one knows where one’s arm is, relative to the body, without needing to directly observe it. This ability, in part, allows humans to interact with the environment without direct observation. This bodily sense is referred to as ”proprioception“. The human body contains various proprioceptors, sensory neurons which provide information about the physical state of the body. This information, along with internal body representations that humans develop over time, allows one to maintain an approximation of their bodily form. Humans also possess an impressive sense of direction and navigation ability. For instance, a blindfolded human can move around a familiar environment and maintain an approximate sense of where they are within that environment. This ability is, in part, enabled by proprioception as it provides one with an approximation of the effects their actions have on their body. The field of Evolutionary Robots (ER) makes extensive use of robotic simulators to carry out simulated robotic evaluations. Research has been conducted into alternate forms of simulation and Simulator Neural Networks (SNNs) were subsequently developed. The speed and accuracy of these SNNs, relative to more typical simulation techniques, is what inspired the approach explored in this research. Robots do not necessarily possess the appropriate hardware to sense their position within an environment. Thus, it was proposed that SNNs could be incorporated into ER controllers to approximate the position of the robot. These SNNs would be executed in parallel to the robot and provide a constant approximation of the robot’s position. This would provide controllers with information that they would not otherwise have, albeit approximate information. Various experiments were carried out which examined both typical ER controllers as well as those which were augmented in the proposed fashion. The augmented controllers were found to outperform typical controllers as well as develop more advanced and efficient behaviours. Furthermore, the augmented controllers demonstrated the ability to solve tasks that regular controllers could not. A potential criticism of the approach suggested in this research is that ER controllers could hypothetically be trained in such a way that the proposed augmentation would be unnecessary. This possibility was investigated and it was found that successfully training controllers in such a manner would be unlikely. Furthermore, the effort involved in fine-tuning this training process would be greater than simply following the approach suggested in this research. Another potential drawback of the suggested approach involved the accuracy of the information that SNNs could provide to controllers. The approximated information was found to diverge over time and negatively affected controller performance. A method to address this issue was proposed and subsequently implemented. This method was demonstrated to be an effective means of reducing the divergence of the SNNs outputs and, in turn, improved controller performance. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
  • Full Text:
  • Date Issued: 2021-04

Evolutionary robotics controllers with location perception facilitated by neural network-based simulators

  • Authors: Phillips, Antin Paul
  • Date: 2021-04
  • Subjects: Grahamstown (South Africa) , Eastern Cape (South Africa) , Neural networks (Computer science) -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52137 , vital:43444
  • Description: Humans impressively maintain a real-time approximation of their bodily form. For instance, one knows where one’s arm is, relative to the body, without needing to directly observe it. This ability, in part, allows humans to interact with the environment without direct observation. This bodily sense is referred to as ”proprioception“. The human body contains various proprioceptors, sensory neurons which provide information about the physical state of the body. This information, along with internal body representations that humans develop over time, allows one to maintain an approximation of their bodily form. Humans also possess an impressive sense of direction and navigation ability. For instance, a blindfolded human can move around a familiar environment and maintain an approximate sense of where they are within that environment. This ability is, in part, enabled by proprioception as it provides one with an approximation of the effects their actions have on their body. The field of Evolutionary Robots (ER) makes extensive use of robotic simulators to carry out simulated robotic evaluations. Research has been conducted into alternate forms of simulation and Simulator Neural Networks (SNNs) were subsequently developed. The speed and accuracy of these SNNs, relative to more typical simulation techniques, is what inspired the approach explored in this research. Robots do not necessarily possess the appropriate hardware to sense their position within an environment. Thus, it was proposed that SNNs could be incorporated into ER controllers to approximate the position of the robot. These SNNs would be executed in parallel to the robot and provide a constant approximation of the robot’s position. This would provide controllers with information that they would not otherwise have, albeit approximate information. Various experiments were carried out which examined both typical ER controllers as well as those which were augmented in the proposed fashion. The augmented controllers were found to outperform typical controllers as well as develop more advanced and efficient behaviours. Furthermore, the augmented controllers demonstrated the ability to solve tasks that regular controllers could not. A potential criticism of the approach suggested in this research is that ER controllers could hypothetically be trained in such a way that the proposed augmentation would be unnecessary. This possibility was investigated and it was found that successfully training controllers in such a manner would be unlikely. Furthermore, the effort involved in fine-tuning this training process would be greater than simply following the approach suggested in this research. Another potential drawback of the suggested approach involved the accuracy of the information that SNNs could provide to controllers. The approximated information was found to diverge over time and negatively affected controller performance. A method to address this issue was proposed and subsequently implemented. This method was demonstrated to be an effective means of reducing the divergence of the SNNs outputs and, in turn, improved controller performance. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
  • Full Text: false
  • Date Issued: 2021-04

Factors affecting the performance of the wooden furniture manufacturing industry in the Southern Cape

  • Authors: Vheriwa, Prayer
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Furniture making -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52017 , vital:43449
  • Description: The furniture manufacturing industry in South Africa is facing several challenges that affect the performance of firms in this sector. A literature review indicates several factors such as availability of resources; location; access to local markets; access to export markets; and development programmes that may affect the performance of wooden furniture manufacturing firms in the Southern Cape. The purpose of the current study was to fill the knowledge gap on why the performance of wooden furniture manufacturing firms in the Southern Cape has declined. The study intends to contribute to the limited formal information resources on the Southern Cape furniture manufacturing industry. A conceptual framework was developed and employed for investigating factors hypothesised to affect the performance of furniture manufacturing firms in the Southern Cape. The research conducted was explorative. An interpretive paradigm was selected to collect and interpret qualitative data and a positivist paradigm was used for the quantitative component of the study. The quantitative data was subjected to a chi-square test using IBM SPSS statistics software and qualitative data was analysed for meanings and context using ATLAS.ti software. Statistical tests on qualitative and quantitative data were conducted to determine whether sufficient evidence existed to make conclusions on the hypotheses, relating to significant relationships between the selected independent variables for the study and the performance of wooden furniture manufacturing firms in the Southern Cape. The results show that existing development programmes and availability of resources, namely: timber, skilled human resources and availability of finance, influence the performance of furniture manufacturing firms in the Southern Cape. Results further reveal that location; access to local market; and access to export market have a partial influence on the performance of the furniture manufacturing firms in the Southern Cape. The study presents information which serves to improve the capacity for growth of wooden furniture manufacturing firms. Based on the results, recommendations were made to overcome the factors affecting the performance of the furniture manufacturing firms in the Southern Cape. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
  • Full Text: false
  • Date Issued: 2021-04

Fish ecology and ecophysiology in an anthropogenically-altered temporarily open/closed estuary in the warm-temperate region of the Eastern Cape Province, South Africa

  • Authors: Mpinga, Mfundo
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fishes--Ecology--South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52122 , vital:43431
  • Description: Estuaries are globally recognized for their contribution to the coastal marine environment by acting as nursery grounds for numerous marine estuarine-dependent fish species. These linking ecosystems between marine and riverine environments, are ideal for these species due to the habitat diversity, nutrient and food availability, shallower and calmer environments they provide relative to the ocean. Abrupt hydrodynamic and physico-chemical changes which frequently occur in estuaries impose physiological stress and requires superior adaptability in the fish that reside within them. This is exacerbated by anthropogenic modifications to estuaries which affects their natural ecological function. The Seekoei Estuary is one of 192 temporarily open/closed estuaries (TOCEs) in South Africa and these estuaries are characterised by their periodical connection to the sea due to the formation of a mouth berm. These estuaries are the dominant type in South Africa. A lot of research has been done in these kinds of estuaries, however, it is still limited due to their vast numbers. These estuaries are popular for human settlement and this has led to mismanagement due to the lack of ecological information. Furthermore, because of their inability to continuously flush out water, temporarily open closed estuaries are more vulnerable to pollution and anthropogenic modifications. The aim of this study was to assess the small fish community in relation to their environment in the hypersaline anthropogenically-altered Seekoei Estuary, by analysing the spatio-temporal trends of physico-chemical properties, nutrient loads, phytoplankton biomass and fish community structure. In addition, histological adaptation in gills of fish that survive hypersaline water was investigated. The study found that physico-chemical properties were influenced by anthropogenic alterations, in particular adverse water abstraction, instream water obstructions and artificial breaching. Nutrient concentration was found to be influenced by the intense agricultural practices in the upper reaches. It was evident that nutrient concentration (dissolved inorganic phosphorus) coupled with high salinity and optimum temperature (15 oC - 20 oC) affected the phytoplankton biomass. This estuary’s inability to naturally breach makes it vulnerable to phytoplankton blooms. The accumulation of cohesive silt caused by low river inflow, due to water abstraction in the upper reaches, was attributed to this estuary’s prolonged mouth closure. This was exacerbated by the presence of the causeway, which acts as a barrier between the middle and lower estuary. The abundance of marine fish species in the estuary, despite its long closure, indicates that the larvae and juveniles of these species make use of overwash events and brief artificial breaching events to recruit into the estuary. The high species richness in iii sites below the causeway is indicative of the barrier effect, which prevents the migration of some species to the upper reaches. This was evident during a massive fish kill, recorded during this study, which was more severe in sites below the causeway than above it. Chloride cell hyperplasia, mucus secretion and thickening of the epithelial layer in gills of indicator fish species from this estuary was the histological adaptation, which enables these fishes to be tolerant to high salinity. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
  • Full Text: false
  • Date Issued: 2021-04

Flash floods prediction in South African urban areas: Jukskei river catchment as case study

  • Authors: Mawasha, Tshepo Sylvester
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Geographic information systems
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52059 , vital:43429
  • Description: This study explored the change relation of multi-temporal land-use/land-cover (LULC) conditions in order to determine how they contribute to change in surface runoff volumes and peak discharge, in an effort to predict flash flooding within the Jukskei River catchment. The research is divided into three main parts: (1) LULC change modeling, (2) rainfall-runoff modeling, and (3) flash floods prediction. Three multi-temporal satellite images of Landsat-5 MMS (1987), Landsat-5 TM (2001) and Landsat-8 OLI (2015) were used for LULC modeling. The analysis of the LULC model revealed that there is a continuous increment in built-up area, from 37.7% to 56.2%, in the expense of other LULC classes for the 28-years preceding this study (i.e., 1987 to 2015). Rainfall-runoff model output results revealed that, for these 28 years, there has been an increase in surface runoff due to change in LULC by 21.5%, 32.9% and 45.5% for 1987, 2001 and 2015, respectively. Due to an increase in surface runoff volume and impervious surface over time, the analysis of HEC-RAS/GeoRAS showed that floodplain extent, flood depth, flood velocity, depth-velocity and the level of damage increases especially in low elevation areas and areas at closed proximity to the Jukskei River. Thus, the building structures and infrastructures are at risk of being affected by flash floods during the rainy season. The findings of this study are expected to be used as basic data for the identification of causative factors of flash floods, areas that generate high surface runoff volume, and the prediction of flash floods within the catchment in future. The flood damage maps developed in this study will be useful to policy-makers and the relevant authorities, as well as to local residents, in finding suitable measures for residential development along the floodplain while reducing flood risk in the study area. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
  • Full Text: false
  • Date Issued: 2021-04

Fragmentation of the Albany Thicket Biome: consequences for the biodiversity and health of thicket vegetation

  • Authors: Carvalho, Shandon Luke
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Fragmented landscapes
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52344 , vital:43599
  • Description: The dense impenetrable vegetation of the Albany Thicket Biome is highly resistant to a wide variety of disturbances but, once disturbed, lacks the regenerative qualities that allow it to return to a stable state. Agricultural development is the main cause of degradation in this biome, creating a landscape consisting of patches of thicket vegetation scattered throughout land cleared for crops or transformed through grazing by domestic livestock. The main objective of this study is to determine the health, status and biodiversity of thicket fragments as it relates to elephant impacts. The level of fragmentation and the remaining extent of intact thicket were investigated as its current status is unknown. The findings suggest that the Thicket Biome is highly fragmented as almost 50% of solid thicket has been cleared, transformed or degraded by agricultural or urban development. For Arid Thicket, the level of fragmentation and the remaining extent of intact thicket could not be determined and both could potentially be greater. For the intact thicket of Dune, Mesic and Valley Thicket types, patch sizes ranged between almost 6 and 876 km2 while the weighted mean was between 2 and 251 km2 . Remote sensing methods (NDVI) were used to determine whether the health of thicket could be remotely assessed. The thicket within and beyond the extent of piospheres around watering holes is subjected to different levels of herbivory. These different levels were compared to corresponding NDVI values with the latter accurately measuring the impact of herbivores along a gradient and providing a method to assess the health of thicket vegetation. Ground surveys of the edge effect, along thicket fragments adjacent to open pastures and separated by cut lines, were conducted. Based on these surveys, the extent of the edge effect was established at a distance of 7 m into thicket fragments separated by cut lines but could not be determined for thicket fragments adjacent to open pastures. Ground surveys were also conducted to assess the health of thicket vegetation exposed to different levels of herbivory, including the impact of elephants (Loxodonta africana). Results showed that different elephant densities produced different levels of impact that could be described in terms of changes in species richness, species diversity, plant height and cover, and growth form composition. Lastly, the findings of the health-based assessments were combined with elephant densities to develop a model that could assess the health of thicket vegetation using a range of ecological variables and relate it to an ideal range of elephant densities. This assessment method was tested at the Addo Elephant National Park and results showed that an elephant density of 1 elephant/km2 would maintain the appropriate diversity, structure and composition of thicket. , Thesis (MSc) -- Faculty of Science, Department of Botany, 2021
  • Full Text: false
  • Date Issued: 2021-04

Impact of feeding milk once-a-day on growth and development of jersey calves

  • Authors: Myburgh, Albertus Petrus
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Calves -- Feeding and feeds
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52095 , vital:43438
  • Description: In conventional calf rearing systems calves are fed milk twice a day. Calves are normally housed in a calf shed, kept in individual pens or in groups. The goal should be to limit mor-talities to less than 5% from birth to 30 days. This can be achieved by reducing animal stress, controlling diseases and feeding the animals properly. The immune function can be de-pressed by inadequate nutrition which will increase susceptibility to diseases. Key objective on a dairy farm should be to rear a healthy calf until the calf reaches the optimum mating weight. Digestive disorders and respiratory diseases are the main causes of mortalities of young calves. Jersey calves at Outeniqua Research Farm are kept in movable hutches out-side, for 8 weeks and whole milk is fed only once a day. Although it is common practice to feed milk to calves twice-a-day, Jersey calves are raised with great success by feeding whole milk once-a-day, but proven data was never collected to indicate that feeding whole milk to Jersey calves does not compromise growth or development of calves. Much research was done on feeding of milk to Holstein calves, but little was done on Jersey calves. Research also shows results on feeding of milk replacer rather than whole milk. This raised the question of can whole milk be fed once-a-day successfully to Jersey calves with-out compromising growth and development and what are the advantages of feeding whole milk once-a-day to Jersey calves? , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
  • Full Text: false
  • Date Issued: 2021-04

Incidence of parasitic trematodes effects on the energetics and behaviour of Coryogalops sordidus (Family: Gobiidae) resident in microbialite pools, warm temperate South Africa

  • Authors: Du Toit, Hendrik Daniël
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Gobiidae -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52458 , vital:43666
  • Description: Coryogalops sordidus(Epaulette goby), is a cryptobenthic species of the Family Gobiidae that iscommonly foundoccupying turbulent surf zones, calm rock pools, and sand and mud flats, where they are generally carnivorous predators. The distribution of C. sordidushas been recorded for Kenya, Tanzania, Mozambique, and South Africa. The species is also resident in the microbialite pools on the temperate south east coast of South Africa. Recent reports indicated these gobies to be covered in numerous dark lesions, possibly suggesting that the microbialite pools are a sub-optimal habitat. Preliminary analyses have indicated that the dark lesions are a result of encysted metacercaria of a digenetic trematode (fluke). There werehowever,no current recorded parasiticspecies occurring within microbialite pool nor any records of any parasitic species utilizingC. sordidus as a host in South Africa. Therefore, the aim of this study was to investigate parasite-host interactions and parasite presence in and around themicrobialite pool systems of Algoa Bay using C. sordidusas a study species. Coryogalops sordiduswas identified to be parasitised by digenetic trematode metacercaria of the Family Diplostomidae Poirier, 1886, localised primarily to the host musculature, fins, eyes, and integument with no settlement on any of the visceral organs. Furthermore, C. sordidus was found additionally parasitised by a green leech (Class: Hirundinea) of the Family Piscicolidae Johnston, 1865, localised exclusively to the ventral body surface, underneath the pelvic fin of the host. Further investigation into the life cycle of the trematode, suggested that the most probable final hosts wereherons,namely Ardea cinereaand Egretta garzetta garzetta, and intermediate host likely being the freshwater gastropod Assimineacf.capensis, present inthe upper microbialite pools. In both the microbialite and neighbouring rock pools trematode prevalence was found to oscillate in response to seasonal chemical and climatic conditions, whereas the secondary piscicolid leech parasite was influencedmoreby host presence than environmental conditions. Greater prevalence and intensity were measured in the microbialite pools suggesting that these systems likely contained a suit of favourable conditions that allowed for greater trematode loads to be maintained as compared to neighbouring rock pools. As parasites often have deleterious effects on their hosts, the response can manifest as an altered host behaviour or an increased energetic debt due to elevated immune response activity and the associated cost of tissue repair at sites of parasite aggregation.This study further investigatedifgobies (C. sordidus) infected with metacercarial cysts display higher metabolic ratesordifferent swimming behaviour compared to non-infected individuals. The results indicated that the metacercarial load carried by infected hosts had on average no significant impact on energetics, swimming ability, or swimming behaviour, concluding that the average metacercarial intensity present on the gobies is therefore below the threshold of an altered host response. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
  • Full Text:
  • Date Issued: 2021-04

Large mammalian fauna of the Palaeo-Agulhas Plain: predicting habitat use and range distribution

  • Authors: Brooke, Christopher F
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Herbivores
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/52332 , vital:43590
  • Description: Understanding the variations in structure and abundance of animals and what leads to their distribution within the landscape has captured the attention of ecologists for centuries. Importantly, knowledge of current behaviour of large mammals can be used to inform historic population dynamics and is essential to understanding how early humans used large mammals as a foraging resource. Central to this thesis and improving our understanding of large herbivores is the Palaeo-Agulhas Plain (PAP) where large mammalian herbivores formed a key food resource for early humans. The PAP, now submerged off the southern Cape of South Africa, formed a novel ecosystem during lower sea levels. Characterised by large expanses of nutrient rich grasslands and large grazing herbivores, the PAP stands in stark contrast to the nutrient poor fynbos ecosystems that is in the southern Cape today. In this thesis I focus on the Last Glacial Maximum (LGM; ~20 ka) when the PAP was last fully exposed to answer questions relating to the habitat use and range distribution of large herbivores. Importantly, through the Paleoscape Project, modelled climate, soil and vegetation have made these recreations of large mammals possible. Using modelled climate and vegetation this thesis aims to model the large herbivore communities and understand the influence of early humans on the PAP during the LGM for successful integration into the PaleoscapeABM (the PAP agent-based model). To improve our understanding of large mammals on the PAP I identified five large herbivores that became extinct on the PAP since the LGM and modelled their behavioural and physical traits using k-Nearest Neighbour imputation. I predicted the biomass of large herbivores across the PAP using actual biomass of large herbivores from 39 protected areas across South Africa (spanning five functional groups to include the extinct species) across a rainfall gradient and different biomes. The distribution of large herbivores would likely have been driven by similar top-down and bottom-up drivers we see in large herbivore ecology today. Knowing this, I created a predictive model for large mammals by predicting the probability of occurrence of functional groups of large herbivores in relation to environmental drivers and humans. Results showed that all species (except Antidorcas australis) were adapted to the grassy environment of the PAP and these specialisations likely contributed to their extinction along with changing climates and intensified hunting from humans. When predicting herbivore viii biomass, biome was the most important factor influencing the relationship between herbivores and rainfall. In general, large herbivore biomass increased with rainfall across biomes, except for grassland. Finally, I showed the probability of occurrence of large herbivores was influenced by early humans, water availability and a landscape of fear on the PAP. Through this thesis I have successfully provided detailed accounts of the biomass and probability of occurrence of large herbivores on the PAP. Importantly, this information can be seamlessly integrated into the PaleoscapeABM. Finally, I highlight the importance of this knowledge in understanding early humans, the potential shortcomings of this study and resulting areas where research needs to be focused. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Management, 2021
  • Full Text: false
  • Date Issued: 2021-04

Linking agrochemical pollution with the aquatic ecological integrity of the Twee River Catchment, Western Cape

  • Authors: Brink, Zanné
  • Date: 2021-04
  • Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ecological integrity
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/52326 , vital:43588
  • Description: This study was initiated in the Twee River system due to the threat posed by agrochemicals on the occurrence of the endemic and endangered fish species found within the catchment. Poor knowledge and understanding of the environmental effects of fertilizers, pesticides and other agrochemicals among small and large commercial farmers within the study area, in combination with their intensive use may have resulted in chemical contamination above environmentally safe concentrations. Numerous studies have highlighted the fact that more research needs to be conducted to identify the key threats to the continued existence of specifically the Critically Endangered Sedercypris erubescens. The overall aim of this study was to determine the spatial and temporal patterns in aquatic ecosystem diversity in the Twee River catchment as indicated by macroinvertebrate and native fish distribution and abundance. It was further investigated if there was a link between agrochemical pollution and the aquatic ecological integrity of the Twee River catchment. Selected sampling sites were identified and sampled to determine the presence and concentration of pesticides entering the water of the Twee River system during run-off and event-based spraying. Furthermore, the effect of these pesticides on the distribution and abundance of the aquatic biota were determined using SASS5 for the macroinvertebrate populations and visually sampling the distribution of the native and non-native fish in the Twee River catchment. This study supports suggestions made by previous studies, that sub-lethal to lethal concentrations of insecticides could be a threat to the long-term survival of benthic macroinvertebrates and potentially the more sensitive endemic fish species within the Twee River system. More focussed research is needed to address impacts of pesticides within this catchment. Agricultural and conservation efforts should be aimed at developing of a shared vision amongst stakeholders, to allow for the longterm conservation of the endemic fish of the Twee River. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
  • Full Text: false
  • Date Issued: 2021-04
  • Disclaimer
  • Privacy
  • Copyright
  • Contact