Modelling false positive reduction in maritime object detection
- Authors: Nkele, Nosiphiwo
- Date: 20xx
- Subjects: Computer vision Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/17168 , vital:40862
- Description: Target detection has become a very significant research area in computer vision with its applications in military, maritime surveillance, and defense and security. Maritime target detection during critical sea conditions produces a number of false positives when using the existing algorithms due to sea waves, dynamic nature of the ocean, camera motion, sea glint, sensor noise, sea spray, swell and the presence of birds. The main question that has been addressed in this research is how can object detection be improved in maritime environment by reducing false positives and promoting detection rate. Most of Previous work on object detection still fails to address the problem of false positives and false negatives due to background clutter. Most of the researchers tried to reduce false positives by applying filters but filtering degrades the quality of an image leading to more false alarms during detection. As much as radar technology has previously been the most utilized method, it still fails to detect very small objects and it may be applied in special circumstances. In trying to improve the implementation of target detection in maritime, empirical research method was proposed to answer questions about existing target detection algorithms and techniques used to reduce false positives in object detection. Visible images were retrained on a pre-trained Faster R-CNN with inception v2. The pre-trained model was retrained on five different sample data with increasing size, however for the last two samples the data was duplicated to increase size. For testing purposes 20 test images were utilized to evaluate all the models. The results of this study showed that the deep learning method used performed best in detecting maritime vessels and the increase of dataset improved detection performance and false positives were reduced. The duplication of images did not yield the best results; however, the results were promising for the first three models with increasing data.
- Full Text:
- Date Issued: 20xx
- Authors: Nkele, Nosiphiwo
- Date: 20xx
- Subjects: Computer vision Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/17168 , vital:40862
- Description: Target detection has become a very significant research area in computer vision with its applications in military, maritime surveillance, and defense and security. Maritime target detection during critical sea conditions produces a number of false positives when using the existing algorithms due to sea waves, dynamic nature of the ocean, camera motion, sea glint, sensor noise, sea spray, swell and the presence of birds. The main question that has been addressed in this research is how can object detection be improved in maritime environment by reducing false positives and promoting detection rate. Most of Previous work on object detection still fails to address the problem of false positives and false negatives due to background clutter. Most of the researchers tried to reduce false positives by applying filters but filtering degrades the quality of an image leading to more false alarms during detection. As much as radar technology has previously been the most utilized method, it still fails to detect very small objects and it may be applied in special circumstances. In trying to improve the implementation of target detection in maritime, empirical research method was proposed to answer questions about existing target detection algorithms and techniques used to reduce false positives in object detection. Visible images were retrained on a pre-trained Faster R-CNN with inception v2. The pre-trained model was retrained on five different sample data with increasing size, however for the last two samples the data was duplicated to increase size. For testing purposes 20 test images were utilized to evaluate all the models. The results of this study showed that the deep learning method used performed best in detecting maritime vessels and the increase of dataset improved detection performance and false positives were reduced. The duplication of images did not yield the best results; however, the results were promising for the first three models with increasing data.
- Full Text:
- Date Issued: 20xx
Assessment of antibacterial potentials of Garcinia Kola seed extracts and their interactions with antibiotics
- Authors: Sibanda, Thulani
- Date: 2007
- Subjects: Drug resistance in microorganisms , Garcinia , Antibiotics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19236 , vital:43038
- Description: The antibacterial potency of the extracts of the seed of Garcinia kola (bitter kola) was investigated in this study against a panel of referenced, environmental and clinical bacterial strains. The killing rates of the active extract as well as their potential for combination antibacterial therapy with standard antibiotics were also elucidated using standard procedures. The aqueous and acetone extracts of the seed were screened for activity against 27 bacterial isolates. The aqueous extract exhibited activity mainly against Gram positive organisms with Minimum inhibitory concentration (MIC) values ranging from 5 mgml-1 – 20 mgml-1, while the acetone extract showed activity against both Gram negative and Gram positive organisms with MIC values ranging from 10 mgml-1 - 0.156 mgml-1. The acetone extract also showed rapid bactericidal activity against Staphylococcus aureus ATCC 6538 with a 3.097 Log10 reduction in counts within 4 hours at 0.3125 mgml-1 and a 1.582 Log10 reduction against Proteus vulgaris CSIR 0030 at 5 mgml-1 after 1 hour. In addition, the aqueous, methanol and acetone extracts of the seeds also exhibited activity against four clinical strains of Staphylococcus isolated from wound sepsis specimens. The MIC values for the aqueous extract were 10 mgml-1 for all the isolates while the acetone and methanol extracts had lower values ranging from 0.3125 - 0.625 mgml-1. The acetone extract was strongly bactericidal against Staphylococcus aureus OKOH3 resulting in a 2.70 Log10 reduction in counts at 1.25 mgml-1 within 4 hours of exposure and a complete elimination of the organism after 8 hours. The bactericidal activity of the same extract against Staphylococcus aureus OKOH1 was weak, achieving only a 2.92 Log10 reduction in counts at 1.25 mgml-1 (4× MIC) in 24 hours. In the test for interactions between the acetone extract of the seeds and antibiotics, synergistic interactions were observed largely against Gram positive organisms using the FIC indices, (indices of 0.52 - 0.875) with combinations against Gram negatives yielding largely antagonistic interactions (indices of 2.0 to 5.0). Synergy (≥ 1000 times or ≥ 3 Log10 potentiation of the bactericidal activity) against both Gram negative and Gram positive organisms was detected by time kill assays mainly involving the antibiotics tetracycline, chloramphenicol, amoxycillin and penicillin G. Combinations involving erythromycin and ciprofloxacin consistently gave antagonistic or indifferent interactions. We conclude that the acetone extract of Garcinia kola seeds possess strong bactericidal activities against both Gram positive and Gram negative organisms and can be therapeutically useful in the treatment of bacterial infections including the problematic staphylococcal wound infections. In addition, the acetone extract can be a potential source of broad spectrum resistance modifying compounds that can potentially improve the performance of antibiotics in the treatment of drug resistant infections. , Thesis (MSc)-- Microbiology, University of Fort Hare, 2007
- Full Text:
- Date Issued: 2007
- Authors: Sibanda, Thulani
- Date: 2007
- Subjects: Drug resistance in microorganisms , Garcinia , Antibiotics
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19236 , vital:43038
- Description: The antibacterial potency of the extracts of the seed of Garcinia kola (bitter kola) was investigated in this study against a panel of referenced, environmental and clinical bacterial strains. The killing rates of the active extract as well as their potential for combination antibacterial therapy with standard antibiotics were also elucidated using standard procedures. The aqueous and acetone extracts of the seed were screened for activity against 27 bacterial isolates. The aqueous extract exhibited activity mainly against Gram positive organisms with Minimum inhibitory concentration (MIC) values ranging from 5 mgml-1 – 20 mgml-1, while the acetone extract showed activity against both Gram negative and Gram positive organisms with MIC values ranging from 10 mgml-1 - 0.156 mgml-1. The acetone extract also showed rapid bactericidal activity against Staphylococcus aureus ATCC 6538 with a 3.097 Log10 reduction in counts within 4 hours at 0.3125 mgml-1 and a 1.582 Log10 reduction against Proteus vulgaris CSIR 0030 at 5 mgml-1 after 1 hour. In addition, the aqueous, methanol and acetone extracts of the seeds also exhibited activity against four clinical strains of Staphylococcus isolated from wound sepsis specimens. The MIC values for the aqueous extract were 10 mgml-1 for all the isolates while the acetone and methanol extracts had lower values ranging from 0.3125 - 0.625 mgml-1. The acetone extract was strongly bactericidal against Staphylococcus aureus OKOH3 resulting in a 2.70 Log10 reduction in counts at 1.25 mgml-1 within 4 hours of exposure and a complete elimination of the organism after 8 hours. The bactericidal activity of the same extract against Staphylococcus aureus OKOH1 was weak, achieving only a 2.92 Log10 reduction in counts at 1.25 mgml-1 (4× MIC) in 24 hours. In the test for interactions between the acetone extract of the seeds and antibiotics, synergistic interactions were observed largely against Gram positive organisms using the FIC indices, (indices of 0.52 - 0.875) with combinations against Gram negatives yielding largely antagonistic interactions (indices of 2.0 to 5.0). Synergy (≥ 1000 times or ≥ 3 Log10 potentiation of the bactericidal activity) against both Gram negative and Gram positive organisms was detected by time kill assays mainly involving the antibiotics tetracycline, chloramphenicol, amoxycillin and penicillin G. Combinations involving erythromycin and ciprofloxacin consistently gave antagonistic or indifferent interactions. We conclude that the acetone extract of Garcinia kola seeds possess strong bactericidal activities against both Gram positive and Gram negative organisms and can be therapeutically useful in the treatment of bacterial infections including the problematic staphylococcal wound infections. In addition, the acetone extract can be a potential source of broad spectrum resistance modifying compounds that can potentially improve the performance of antibiotics in the treatment of drug resistant infections. , Thesis (MSc)-- Microbiology, University of Fort Hare, 2007
- Full Text:
- Date Issued: 2007
Photovoltaic-powered wireless communication system for rural schools outside national utility grid
- Kaseke, Richmore https://orcid.org/0000-0002-8295-5016
- Authors: Kaseke, Richmore https://orcid.org/0000-0002-8295-5016
- Date: 2007-02
- Subjects: Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/29032 , vital:76492
- Description: Access to global information is inarguably one of the key ways of bringing development to any community. In developing worlds, many rural schools lie outside both the Internet Service Provider’s (ISP) cable network and the national utility grid. Rapid developments in information and communication technology (ICT) continue to widen the digital divide between urban and rural schools. In South Africa, although these rural areas are outside the ISP’s cable network, they enjoy excellent mobile (cellular) communications network coverage. Fortunately, leading mobile operators in the country (MTN and Vodacom) have incorporated mobile data packet services into their cellular communication networks since 2002. A stand-alone photovoltaic (PV) system for powering ICT equipment in off grid rural schools was designed and installed; and its performance monitored. Performance of the system was considered in two categories, which are; cost and service performance. In cost performance, return on investment (ROI) and payback period (PB) are the two critical considerations. The PV system designed in this study gave an impressive ROI and PB of 286percent and 5 years, respectively. In order to monitor and evaluate the service performance a data acquisition system (DAS) was designed and installed. Besides proving the potential of PV in powering ICT equipment, results from the DAS also suggested a more efficient way of employing PV as a power source for powering equipment that is based on Switched-Mode Power Supply Units. Concurrent and continuous change in irradiance and temperature result in a four-segment pattern of rising and falling module efficiency throughout the day. Generally, modules produce more energy on cooler sunny days than hotter sunny days. Infrared (IR) Thermography was also used as part of both indoor and outdoor module tests. During indoor tests at pre-deployment stage, IR Thermography showed development of hot spots in mismatched cells of reverse-biased modules. On the outdoors, IR Thermography reiterated the effect of bird droppings on module surfaces byshowing hot spots forming on areas covered by the droppings. For internet connectivity, a customized Mobile Internet Device (MIDevice) was designed, built and tested. The device allows remote computer systems to be connected to the Internet via the already existing mobile communication network using General Packet Radio Services (GPRS). An entire rural school local area network (LAN) can be connected to the Internet via a single MIDevice. An experimental setup was designed in order to monitor and evaluate performance of GPRS in specific and mobile Internet solutions in general. Results obtained proved that GPRS can indeed be a solution for remote Internet connectivity in rural schools. In order to improve performance of GPRS or mobile Internet connections, caching, pop-up blocking and proxy filtering are necessary. , Thesis (MSc) -- Faculty of Science and Agriculture, 2007
- Full Text:
- Date Issued: 2007-02
- Authors: Kaseke, Richmore https://orcid.org/0000-0002-8295-5016
- Date: 2007-02
- Subjects: Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/29032 , vital:76492
- Description: Access to global information is inarguably one of the key ways of bringing development to any community. In developing worlds, many rural schools lie outside both the Internet Service Provider’s (ISP) cable network and the national utility grid. Rapid developments in information and communication technology (ICT) continue to widen the digital divide between urban and rural schools. In South Africa, although these rural areas are outside the ISP’s cable network, they enjoy excellent mobile (cellular) communications network coverage. Fortunately, leading mobile operators in the country (MTN and Vodacom) have incorporated mobile data packet services into their cellular communication networks since 2002. A stand-alone photovoltaic (PV) system for powering ICT equipment in off grid rural schools was designed and installed; and its performance monitored. Performance of the system was considered in two categories, which are; cost and service performance. In cost performance, return on investment (ROI) and payback period (PB) are the two critical considerations. The PV system designed in this study gave an impressive ROI and PB of 286percent and 5 years, respectively. In order to monitor and evaluate the service performance a data acquisition system (DAS) was designed and installed. Besides proving the potential of PV in powering ICT equipment, results from the DAS also suggested a more efficient way of employing PV as a power source for powering equipment that is based on Switched-Mode Power Supply Units. Concurrent and continuous change in irradiance and temperature result in a four-segment pattern of rising and falling module efficiency throughout the day. Generally, modules produce more energy on cooler sunny days than hotter sunny days. Infrared (IR) Thermography was also used as part of both indoor and outdoor module tests. During indoor tests at pre-deployment stage, IR Thermography showed development of hot spots in mismatched cells of reverse-biased modules. On the outdoors, IR Thermography reiterated the effect of bird droppings on module surfaces byshowing hot spots forming on areas covered by the droppings. For internet connectivity, a customized Mobile Internet Device (MIDevice) was designed, built and tested. The device allows remote computer systems to be connected to the Internet via the already existing mobile communication network using General Packet Radio Services (GPRS). An entire rural school local area network (LAN) can be connected to the Internet via a single MIDevice. An experimental setup was designed in order to monitor and evaluate performance of GPRS in specific and mobile Internet solutions in general. Results obtained proved that GPRS can indeed be a solution for remote Internet connectivity in rural schools. In order to improve performance of GPRS or mobile Internet connections, caching, pop-up blocking and proxy filtering are necessary. , Thesis (MSc) -- Faculty of Science and Agriculture, 2007
- Full Text:
- Date Issued: 2007-02
Numerical quadrature of oscillatory and non-oscillatory integrals
- Dukuza, Kenneth Njengele https://orcid.org/0000-0002-4525-7390
- Authors: Dukuza, Kenneth Njengele https://orcid.org/0000-0002-4525-7390
- Date: 2009
- Subjects: Oscillations , Numerical integration , Numerical analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24304 , vital:62600
- Description: In this dissertation we develop efficient new methods and techniques to numerically evaluate integrals of both oscillatory and non oscillatory kind. We have done a comprehensive literature review on the existing methods and made some modifications to them so as to cope with difficulties such as oscillations and strong singularities. In the numerical algorithms we have used mainly the MATLAB source code. Our results have been compared with well known methods by renowned authors in this field. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009
- Authors: Dukuza, Kenneth Njengele https://orcid.org/0000-0002-4525-7390
- Date: 2009
- Subjects: Oscillations , Numerical integration , Numerical analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24304 , vital:62600
- Description: In this dissertation we develop efficient new methods and techniques to numerically evaluate integrals of both oscillatory and non oscillatory kind. We have done a comprehensive literature review on the existing methods and made some modifications to them so as to cope with difficulties such as oscillations and strong singularities. In the numerical algorithms we have used mainly the MATLAB source code. Our results have been compared with well known methods by renowned authors in this field. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009
Effects of social and ecological factors on cattle grazing strategies in semi-arid communal rangelands of the Eastern Cape Province, South Africa
- Moyo, Bethwell (https://orcid.org/0000-0001-7524-9028)
- Authors: Moyo, Bethwell (https://orcid.org/0000-0001-7524-9028)
- Date: 2009-09
- Subjects: Communal rangelands--South Africa--Eastern Cape , Grazing--South Africa--Eastern Cape , Range Management--South Africa--Eastern Cape South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/25461 , vital:64279
- Description: Communal rangelands are the main source of livestock feed for resource poor communal farmers. They are characterized by heavy stocking and poor management which is perceived to be the cause of the prevalent degradation hence the incessant calls for introduction of rotational grazing. Rotational grazing has been associated with improved rangeland condition and animal performance in commercial farms, hence the call that it needs to be introduced in communal areas. Management of communal rangelands within the rotational grazing context requires some fundamental understanding of the relationship between current rangeland use, socio-economic and ecological factors determining the present use of these areas. The objective of this study was to assess how historic tenure and patterns of use have influenced grazing practices and institutional structures, and to identify institutional and ecological factors determining present grazing strategies. Focus group discussions and questionnaire surveys in 11 communities revealed that villagers consider fences and paddocks as the best intervention to improve range management. Furthermore, it was shown that lack of strong local-level institutions, little or no knowledge of veld management, absence of rules and lack of seasonal restrictions on rangeland resource use are additional constraints that need to be considered for any rotational grazing intervention to be embraced. Communal areas vary in household head profiles, and this affects the livestock ownership patterns, which indirectly influences rangeland management. The fact that most of the income for communal area people is from state grants, makes farming secondary and the attention put on rangeland management would therefore be minimal. At present the weak local level institutions would therefoe make any plans to introduce rotational grazing difficult. Communal area grazing strategies are further influenced by rangeland heterogeneity caused by different factors. To understand these factors, the relationship between vegetation parameters in different patches and associated soil parameters was examined. Heterogeneity due to seasonal variation in the biomass of herbaceous vegetation was observed at Magwiji‘s sweetveld, with frequently selected patches having a significantly (p < 0.05) higher biomass in autumn (791 kg ha-1) and winter (528 kg ha-1), while in summer and spring there was no significant (p > 0.05) difference in biomass between frequently selected and less selected patches. The present situation in which communal areas support large livestock populations under continuous grazing is due to the fact that cattle would adjust to changes in forage availability by seeking higher biomass patches in times of forage scarcity as observed in Magwiji. At the coastal forest thornveld of Mnyameni the Canonical Correspondence Analysis (CCA) showed that the first axis was significantly correlated with soil organic carbon (r = -1, p < 0.05). Furthermore, the species that were significantly correlated with the first axis were Cynodon dactylon and Pennisetum clandestinum. These species were mainly found in sites that were preferred in April and June. At the sourveld of Upper Mnxe the first axis was significantly correlated with soil pH (r = 0.9, p < 0.05). At this rangeland, sites selected in June were associated with alkaline soils; characterized by a history of human settlement and dominated by Eragrostis superba and Heteropogon contortus. Soil electrical conductivity (EC) separated species (r = 0.9; p < 0.05) along the first axis at Magwiji, with mountain top sites selected in April and June having low EC and dominated by Digitaria eriantha, Eragrostis superba and Andropogon appendiculatus. Rangeland heterogeneity is caused by various factors, ranging from human disturbance to topography. These factors have an effect on the soil properties, and therefore, vegetation and thus lead to the observed heterogeneity which shapes the utilization patterns of these rangelands, and hence their continued support of large populations of livestock. To understand the effects of seasonal and spatial variation in resource use pattern and implications on range management, differences in cattle activity patterns in relation to veld type, season, daytime, management type (kraaling) and forage quality were examined. Seasonal activity patterns were only significant at Upper Mnxe (p < 0.05), with percent of time spent grazing (77 percent), resting (35 percent) and walking (24 percent) being higher in April, November and June respectively. , Thesis (PHD) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-09
- Authors: Moyo, Bethwell (https://orcid.org/0000-0001-7524-9028)
- Date: 2009-09
- Subjects: Communal rangelands--South Africa--Eastern Cape , Grazing--South Africa--Eastern Cape , Range Management--South Africa--Eastern Cape South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/25461 , vital:64279
- Description: Communal rangelands are the main source of livestock feed for resource poor communal farmers. They are characterized by heavy stocking and poor management which is perceived to be the cause of the prevalent degradation hence the incessant calls for introduction of rotational grazing. Rotational grazing has been associated with improved rangeland condition and animal performance in commercial farms, hence the call that it needs to be introduced in communal areas. Management of communal rangelands within the rotational grazing context requires some fundamental understanding of the relationship between current rangeland use, socio-economic and ecological factors determining the present use of these areas. The objective of this study was to assess how historic tenure and patterns of use have influenced grazing practices and institutional structures, and to identify institutional and ecological factors determining present grazing strategies. Focus group discussions and questionnaire surveys in 11 communities revealed that villagers consider fences and paddocks as the best intervention to improve range management. Furthermore, it was shown that lack of strong local-level institutions, little or no knowledge of veld management, absence of rules and lack of seasonal restrictions on rangeland resource use are additional constraints that need to be considered for any rotational grazing intervention to be embraced. Communal areas vary in household head profiles, and this affects the livestock ownership patterns, which indirectly influences rangeland management. The fact that most of the income for communal area people is from state grants, makes farming secondary and the attention put on rangeland management would therefore be minimal. At present the weak local level institutions would therefoe make any plans to introduce rotational grazing difficult. Communal area grazing strategies are further influenced by rangeland heterogeneity caused by different factors. To understand these factors, the relationship between vegetation parameters in different patches and associated soil parameters was examined. Heterogeneity due to seasonal variation in the biomass of herbaceous vegetation was observed at Magwiji‘s sweetveld, with frequently selected patches having a significantly (p < 0.05) higher biomass in autumn (791 kg ha-1) and winter (528 kg ha-1), while in summer and spring there was no significant (p > 0.05) difference in biomass between frequently selected and less selected patches. The present situation in which communal areas support large livestock populations under continuous grazing is due to the fact that cattle would adjust to changes in forage availability by seeking higher biomass patches in times of forage scarcity as observed in Magwiji. At the coastal forest thornveld of Mnyameni the Canonical Correspondence Analysis (CCA) showed that the first axis was significantly correlated with soil organic carbon (r = -1, p < 0.05). Furthermore, the species that were significantly correlated with the first axis were Cynodon dactylon and Pennisetum clandestinum. These species were mainly found in sites that were preferred in April and June. At the sourveld of Upper Mnxe the first axis was significantly correlated with soil pH (r = 0.9, p < 0.05). At this rangeland, sites selected in June were associated with alkaline soils; characterized by a history of human settlement and dominated by Eragrostis superba and Heteropogon contortus. Soil electrical conductivity (EC) separated species (r = 0.9; p < 0.05) along the first axis at Magwiji, with mountain top sites selected in April and June having low EC and dominated by Digitaria eriantha, Eragrostis superba and Andropogon appendiculatus. Rangeland heterogeneity is caused by various factors, ranging from human disturbance to topography. These factors have an effect on the soil properties, and therefore, vegetation and thus lead to the observed heterogeneity which shapes the utilization patterns of these rangelands, and hence their continued support of large populations of livestock. To understand the effects of seasonal and spatial variation in resource use pattern and implications on range management, differences in cattle activity patterns in relation to veld type, season, daytime, management type (kraaling) and forage quality were examined. Seasonal activity patterns were only significant at Upper Mnxe (p < 0.05), with percent of time spent grazing (77 percent), resting (35 percent) and walking (24 percent) being higher in April, November and June respectively. , Thesis (PHD) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-09
Synthesis of bioethanol from lignocellulosic materials: A focus on grass and waste paper as raw materials
- Authors: Vala, Mavula Kikwe
- Date: 2009-12
- Subjects: Ethanol as fuel , Biomass energy , Lignocellulose -- Biotechnology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24499 , vital:63049
- Description: Biofuels are currently recognized as not only a necessity, but an inevitable pathway to secure the planet future energy needs. Food crops have been used (so far) as the biomass for bioethanol and biodiesel production. This has increased concerns over food security and led to the search for diversification and alternative feedstocks for biofuel production. The use of lignocellulosic materials, the most abundant, low cost and easy feedstock to harvest for bioethanol purpose, involves challenging production processes. Several approaches have been used to facilitate the breakdown of the biopolymer structure to produce fermentable sugars that can be converted to ethanol. Most of the approaches have used high temperatures and pressures and have often led to the production of inhibitors of fermentation. In this study, lignocellulosic materials from grass and newsprint were investigated as sources of biomass for bioethanol production using a chemical route (sulfuric acid hydrolysis) which made use of temperatures below 100°C at normal atmospheric pressure. Fermentation of toxic lignocellulosic hydrolyzates was possible after the development of a method for inhibitors removal. The method used treated wood chips as a stationary phase in a chromatographic column to remove inhibitors. This method is expected to be extended to applications such as in municipal wastewater treatment. Sugar yields of 22.26 and 8.9 g/L of hydrolyzate; and an ethanol yield of 184.5 and 130.4 mg/mL of must were achieved for 5g grass and newsprint respectively using optimum conditions of 2percent H2SO4 at 97.5°C for grass and 0.5percent H2SO4 at 97.5°C for newsprint during the hydrolysis process. Pure cellulose was used as a control for the biomass where 254.1 g/L of fermentable sugars were recovered from soluble cellulose and the yield of ethanol was 201.8 mg/mL. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-12
- Authors: Vala, Mavula Kikwe
- Date: 2009-12
- Subjects: Ethanol as fuel , Biomass energy , Lignocellulose -- Biotechnology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24499 , vital:63049
- Description: Biofuels are currently recognized as not only a necessity, but an inevitable pathway to secure the planet future energy needs. Food crops have been used (so far) as the biomass for bioethanol and biodiesel production. This has increased concerns over food security and led to the search for diversification and alternative feedstocks for biofuel production. The use of lignocellulosic materials, the most abundant, low cost and easy feedstock to harvest for bioethanol purpose, involves challenging production processes. Several approaches have been used to facilitate the breakdown of the biopolymer structure to produce fermentable sugars that can be converted to ethanol. Most of the approaches have used high temperatures and pressures and have often led to the production of inhibitors of fermentation. In this study, lignocellulosic materials from grass and newsprint were investigated as sources of biomass for bioethanol production using a chemical route (sulfuric acid hydrolysis) which made use of temperatures below 100°C at normal atmospheric pressure. Fermentation of toxic lignocellulosic hydrolyzates was possible after the development of a method for inhibitors removal. The method used treated wood chips as a stationary phase in a chromatographic column to remove inhibitors. This method is expected to be extended to applications such as in municipal wastewater treatment. Sugar yields of 22.26 and 8.9 g/L of hydrolyzate; and an ethanol yield of 184.5 and 130.4 mg/mL of must were achieved for 5g grass and newsprint respectively using optimum conditions of 2percent H2SO4 at 97.5°C for grass and 0.5percent H2SO4 at 97.5°C for newsprint during the hydrolysis process. Pure cellulose was used as a control for the biomass where 254.1 g/L of fermentable sugars were recovered from soluble cellulose and the yield of ethanol was 201.8 mg/mL. , Thesis (MSc) -- Faculty of Science and Agriculture, 2009
- Full Text:
- Date Issued: 2009-12
Assessment of antibiotic production by some marine actinomycetes belonging to the genera norcadia, saccharopolyspora and kibdellosporangium.
- Koba, Siziwe (https://orcid.org/0000-0002-6761-6403)
- Authors: Koba, Siziwe (https://orcid.org/0000-0002-6761-6403)
- Date: 2010
- Subjects: Actinobacteria , Bacteria , Actinomycetales
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25811 , vital:64488
- Description: Antibacterial potency of the extracts of the three marine actinomycetes strains which were isolated in the Nahoon Beach and tentatively identified as the genera Norcadia, Kibdellosporingium and Saccharopolyspora were investigated in this study against a panel of referenced, environmental and clinical bacterial strains. The ethyl acetate extracts of these marine actinomycetes were screened for activity against 32 bacterial isolates. Out of the 32 organisms, 10 were susceptible to one or all the extracts used. Antibacterial activity was mainly observed against Gram-negative organisms with Minimum inhibitory concentration (MIC) values ranging from 0.078 mg/ml to >10mg/ml. The killing rates of the active extracts were also elucidated using standard procedures. The two extracts NO64 and NO53 showed rapid bactericidal activity against B. pumilus ATCC 14884 and Serratia marcens with a 3Log10 reduction in counts within 6 hours at 3.75 mg/ml and 5 mg/ml respectively. In conclusion, the ethyl acetate extract of these marine actinomycetes strains possess strong bactericidal and bacteriostatic activities against Gram negative organisms and can be therapeutically useful in the treatment of bacterial infections which are mainly caused by Gram negative bacteria. , Thesis (MA) -- Faculty of Science and Agriculture, 2010
- Full Text:
- Date Issued: 2010
- Authors: Koba, Siziwe (https://orcid.org/0000-0002-6761-6403)
- Date: 2010
- Subjects: Actinobacteria , Bacteria , Actinomycetales
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25811 , vital:64488
- Description: Antibacterial potency of the extracts of the three marine actinomycetes strains which were isolated in the Nahoon Beach and tentatively identified as the genera Norcadia, Kibdellosporingium and Saccharopolyspora were investigated in this study against a panel of referenced, environmental and clinical bacterial strains. The ethyl acetate extracts of these marine actinomycetes were screened for activity against 32 bacterial isolates. Out of the 32 organisms, 10 were susceptible to one or all the extracts used. Antibacterial activity was mainly observed against Gram-negative organisms with Minimum inhibitory concentration (MIC) values ranging from 0.078 mg/ml to >10mg/ml. The killing rates of the active extracts were also elucidated using standard procedures. The two extracts NO64 and NO53 showed rapid bactericidal activity against B. pumilus ATCC 14884 and Serratia marcens with a 3Log10 reduction in counts within 6 hours at 3.75 mg/ml and 5 mg/ml respectively. In conclusion, the ethyl acetate extract of these marine actinomycetes strains possess strong bactericidal and bacteriostatic activities against Gram negative organisms and can be therapeutically useful in the treatment of bacterial infections which are mainly caused by Gram negative bacteria. , Thesis (MA) -- Faculty of Science and Agriculture, 2010
- Full Text:
- Date Issued: 2010
Improving Productivity of Maize-based Smallholder Irrigated Cropping Systems: A Case Study of Zanyokwe Irrigation Scheme, Eastern Cape, South Africa
- Authors: Fanadzo, Morris
- Date: 2010
- Subjects: Farms, Small -- South Africa -- Eastern Cape Crop yields -- South Africa -- Eastern Cape Agricultural productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/11009 , vital:36450
- Description: Smallholder irrigation schemes (SIS) in South Africa have performed poorly and failed to achieve the development objectives of sustaining rural livelihoods by increasing crop production and income. Limited knowledge of crop production among farmers is one constraint to improved crop productivity and, yet little research has been carried out to relate agronomic practices to productivity. This study was aimed at identifying strategies to improve the productivity of maize-based smallholder irrigated cropping systems in South Africa, using Zanyokwe irrigation scheme (ZIS) in the Eastern Cape Province as a case study. The research design was emergent, developed progressively as influenced by the progressive analyses that were made. The research work involved two main phases: exploratory studies and refinement on-farm experiments for testing technologies as informed by the exploratory studies. Exploratory studies were aimed at describing farmer crop production practices in major crop enterprises and identifying and prioritizing major agronomic yield constraints. Findings indicated that the overall performance of the cropping systems was poor as evidenced by low overall yields of < 25% of the potential in maize and butternut. Poor management of weeds, soil fertility, plant populations and water, late planting and poor cultivar choice were the most important yield constraints. The average cropping intensity achieved by farmers was only 48%. New hybrids yielded 50 - 65% higher grain than the cultivars commonly grown by farmers. However, farmers favoured their traditional cultivars, as they preferred green maize production as opposed to dry grains. As a result of these findings, focused research was designed on options for iii improving green maize production, soil fertility, crop stand and weed management in crop production. On-farm trials were, therefore, designed to (1) compare the response to nitrogen (N) rate of direct seeded and transplanted maize; (2) evaluate comparative performance of direct seeded and transplanted green maize under farmer management, and to work out the economics of transplanting; (3) investigate the effects of row spacing and atrazine dosage on weed dynamics maize yield; (4) determine the effects of inter-row spacing and plant population on weed dynamics and maize yield; and (5) investigate the effects of pre-plant weed control, N rate and plant population on weed dynamics and butternut yield. Maize transplanting improved crop stand, had earlier maturity and yielded higher at lower N rates compared to direct seeding for both green and grain maize. Total costs that varied were higher by R3 565 ha-1 for transplanted maize compared to direct-seeded maize, but the net benefits from transplanting were also much higher by R8 773 ha-1. Farmers favoured transplanting, citing bigger cobs, early maturity and the absence of seedling damage by birds, when maize was transplanted. However, a follow-up survey conducted during the subsequent year indicated that five of the six farmers abandoned transplanting, citing shortage of labour and high cost of commercially produced seedlings. It was concluded that transplanting is unlikely to be adopted unless the labour intensiveness of manual transplanting can be solved. Increasing atrazine dosage from a third of the label recommended dosage (LRD) and reducing row spacing from 90 to 45 cm resulted in an increase in weed mortality. A 100% kill of annual broadleaf weeds was possible while iv perennial grasses and the annual broadleaf weed, Oxalis latifolia, could not be controlled even at the LRD. However, improved weed mortality with increase in atrazine dosage and/or narrow rows did not translate into improved maize productivity. In butternut, pre-plant weed control resulted in a six-fold decrease in weed biomass and a 100% increase in fruit yield. These findings demonstrated the possibility of incorporation of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on maize yields in smallholder farming systems. The results also suggested that pre-plant weed control is one of the pre-requisite to successful butternut production in SIS in South Africa. Increasing maize population from 40 000 to 60 000 plants ha-1 resulted in a 30% grain yield increase, but decreased length of cobs. Row spacing had no effect on maize yield at 40 000 plants ha-1, but at 60 000 plants ha-1 45 cm rows resulted in 11% higher grain yield (12 547 kg ha-1) than 90 cm rows (11 288 kg ha-1). Butternut yield increased significantly (p < 0.01) with increase in plant population and N rate. The optimum butternut population and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. Pre-plant weed control in butternut resulted in a six-fold decrease in weed biomass. Increasing butternut planting density from 10 000 to 30 000 plants ha-1 decreased weed biomass by 47%. No marketable fruits were obtained when planting was done without prior weed control. This result suggest that application of non-selective herbicide before planting is one technique that can be used by farmers as part of integrated weed management to give the crop a competitive advantage in the early growth stages before the plants start to produce vines. Yield increased significantly (p < 0.01) with increase in plant density and N rate. The optimum plant density and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. These findings emphasise the need to take into consideration production practices by farmers as a basis to build up skills in the management of crop enterprises and the farm as a viable business in any efforts to improve on the performance of SIS in South Africa. Future research should concentrate on labour-saving sustainable production technologies for SIS in South Africa.
- Full Text:
- Date Issued: 2010
- Authors: Fanadzo, Morris
- Date: 2010
- Subjects: Farms, Small -- South Africa -- Eastern Cape Crop yields -- South Africa -- Eastern Cape Agricultural productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/11009 , vital:36450
- Description: Smallholder irrigation schemes (SIS) in South Africa have performed poorly and failed to achieve the development objectives of sustaining rural livelihoods by increasing crop production and income. Limited knowledge of crop production among farmers is one constraint to improved crop productivity and, yet little research has been carried out to relate agronomic practices to productivity. This study was aimed at identifying strategies to improve the productivity of maize-based smallholder irrigated cropping systems in South Africa, using Zanyokwe irrigation scheme (ZIS) in the Eastern Cape Province as a case study. The research design was emergent, developed progressively as influenced by the progressive analyses that were made. The research work involved two main phases: exploratory studies and refinement on-farm experiments for testing technologies as informed by the exploratory studies. Exploratory studies were aimed at describing farmer crop production practices in major crop enterprises and identifying and prioritizing major agronomic yield constraints. Findings indicated that the overall performance of the cropping systems was poor as evidenced by low overall yields of < 25% of the potential in maize and butternut. Poor management of weeds, soil fertility, plant populations and water, late planting and poor cultivar choice were the most important yield constraints. The average cropping intensity achieved by farmers was only 48%. New hybrids yielded 50 - 65% higher grain than the cultivars commonly grown by farmers. However, farmers favoured their traditional cultivars, as they preferred green maize production as opposed to dry grains. As a result of these findings, focused research was designed on options for iii improving green maize production, soil fertility, crop stand and weed management in crop production. On-farm trials were, therefore, designed to (1) compare the response to nitrogen (N) rate of direct seeded and transplanted maize; (2) evaluate comparative performance of direct seeded and transplanted green maize under farmer management, and to work out the economics of transplanting; (3) investigate the effects of row spacing and atrazine dosage on weed dynamics maize yield; (4) determine the effects of inter-row spacing and plant population on weed dynamics and maize yield; and (5) investigate the effects of pre-plant weed control, N rate and plant population on weed dynamics and butternut yield. Maize transplanting improved crop stand, had earlier maturity and yielded higher at lower N rates compared to direct seeding for both green and grain maize. Total costs that varied were higher by R3 565 ha-1 for transplanted maize compared to direct-seeded maize, but the net benefits from transplanting were also much higher by R8 773 ha-1. Farmers favoured transplanting, citing bigger cobs, early maturity and the absence of seedling damage by birds, when maize was transplanted. However, a follow-up survey conducted during the subsequent year indicated that five of the six farmers abandoned transplanting, citing shortage of labour and high cost of commercially produced seedlings. It was concluded that transplanting is unlikely to be adopted unless the labour intensiveness of manual transplanting can be solved. Increasing atrazine dosage from a third of the label recommended dosage (LRD) and reducing row spacing from 90 to 45 cm resulted in an increase in weed mortality. A 100% kill of annual broadleaf weeds was possible while iv perennial grasses and the annual broadleaf weed, Oxalis latifolia, could not be controlled even at the LRD. However, improved weed mortality with increase in atrazine dosage and/or narrow rows did not translate into improved maize productivity. In butternut, pre-plant weed control resulted in a six-fold decrease in weed biomass and a 100% increase in fruit yield. These findings demonstrated the possibility of incorporation of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on maize yields in smallholder farming systems. The results also suggested that pre-plant weed control is one of the pre-requisite to successful butternut production in SIS in South Africa. Increasing maize population from 40 000 to 60 000 plants ha-1 resulted in a 30% grain yield increase, but decreased length of cobs. Row spacing had no effect on maize yield at 40 000 plants ha-1, but at 60 000 plants ha-1 45 cm rows resulted in 11% higher grain yield (12 547 kg ha-1) than 90 cm rows (11 288 kg ha-1). Butternut yield increased significantly (p < 0.01) with increase in plant population and N rate. The optimum butternut population and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. Pre-plant weed control in butternut resulted in a six-fold decrease in weed biomass. Increasing butternut planting density from 10 000 to 30 000 plants ha-1 decreased weed biomass by 47%. No marketable fruits were obtained when planting was done without prior weed control. This result suggest that application of non-selective herbicide before planting is one technique that can be used by farmers as part of integrated weed management to give the crop a competitive advantage in the early growth stages before the plants start to produce vines. Yield increased significantly (p < 0.01) with increase in plant density and N rate. The optimum plant density and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. These findings emphasise the need to take into consideration production practices by farmers as a basis to build up skills in the management of crop enterprises and the farm as a viable business in any efforts to improve on the performance of SIS in South Africa. Future research should concentrate on labour-saving sustainable production technologies for SIS in South Africa.
- Full Text:
- Date Issued: 2010
Prevalence of Listeria pathogens in effluents of some wastewater treatment facilities in the Eastern Cape Province of South Africa
- Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape Sewage -- Purification -- South Africa -- Eastern Cape Water -- Pollution -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7826 , vital:30747
- Description: astewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community.
- Full Text:
- Date Issued: 2010
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape Sewage -- Purification -- South Africa -- Eastern Cape Water -- Pollution -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7826 , vital:30747
- Description: astewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community.
- Full Text:
- Date Issued: 2010
Optimizing geochemical sampling sizes and quantifying uncertainties for environmental risk assessment using Anglogold-Ashanti Gold Mines as a case study
- Authors: Chihobvu, Elizabeth
- Date: 2010-04
- Subjects: Environmental risk assessment , Geochemical prospecting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24443 , vital:62796
- Description: Generally, and particularly in South Africa, limited work done on the development of methodologies for sample sizing and quantifying uncertainties in geochemical sampling and analyses. As a result, little trust is placed on the long-term predictions of geochemical modelling for Environmental Risk Assessment (E.R.A). In addition, this leads to the slow approval of mining authorisations, water use licenses and mine closure plans. This dissertation addresses this deficiency in geochemical sampling and analyses specifically for ERA and proposes two methodologies (i) for quantifying uncertainties in geochemical sampling and analysis as a function of sample size and analyses and (ii) for determining the optimum sample size to ensure data quality. The statistical analysis approach was adopted as the best method for sample size determination. The approach is based on the premise that the size of the study sample is critical to producing meaningful results. The size of the required samples depends on a number of factors including purpose of the study, available budget, variability of the population being sampled, acceptable errors and confidence level. The methodology for estimating uncertainty is a fusion of existing methodologies for quantifying measurement uncertainty. The methodology takes a holistic view of the measurement process to include all processes involved in obtaining measurement results as possible uncertainty components. Like the statistical analysis approach, the methodology employs basic statistical principles in estimating the size of uncertainty, associated with a given measurement result. The approach identifies each component of uncertainty; estimates the size of each component and sums the contribution of each component in order to approximate the overall uncertainty value, associated with a given measurement result. The two methods were applied to Acid-Base Accounting (ABA) data derived from geochemical assessment for ERA of the West Wits and Vaal River (Ashanti Gold mines) tailings dams undertaken by Pulles and Howard de Lange Inc. on behalf of AngloGold Ltd. The study was aimed at assessing and evaluating the potential of tailings dams in the two mining areas to impact on water quality and implications of this in terms of mine closure and rehabilitation. Findings from this study show that the number of samples needed is influenced by the purpose of the study, size of the target area, nature and type of material, budget, acceptable error and the confidence level required, among other factors. Acceptable error has an exponential relationship with sample size hence one can minimize error by increasing sample size. While a low value of acceptable error value and high confidence are always desirable, a tradeoff among these competing factors must be found, given the usually limited funds and time. The findings also demonstrated that uncertainties in geochemical sampling and analysis are unavoidable. They arise from the fact that only a small portion of the population rather than a census is used to derive conclusions about certain characteristics of the target population. This is further augmented by other influential quantities that affect the accuracy of the estimates. Effects such as poor sampling design, inadequate sample size, sample heterogeneity and other factors highly affect data quality and representivity hence measurement uncertainty. Among these factors, those associated with sampling, mainly heterogeneity was found to be the strongest contributing factor toward overall uncertainty. This implies an increased proportion of expenditure should be channelled toward sampling to minimise uncertainty. Uncertainties can be reduced by adopting good sampling practices and increasing sample size, among other methods. It is recommended that more information be made available for proper uncertainty analysis. , Thesis (MSc) -- Faculty of Science and Agriculture, 2010
- Full Text:
- Date Issued: 2010-04
- Authors: Chihobvu, Elizabeth
- Date: 2010-04
- Subjects: Environmental risk assessment , Geochemical prospecting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24443 , vital:62796
- Description: Generally, and particularly in South Africa, limited work done on the development of methodologies for sample sizing and quantifying uncertainties in geochemical sampling and analyses. As a result, little trust is placed on the long-term predictions of geochemical modelling for Environmental Risk Assessment (E.R.A). In addition, this leads to the slow approval of mining authorisations, water use licenses and mine closure plans. This dissertation addresses this deficiency in geochemical sampling and analyses specifically for ERA and proposes two methodologies (i) for quantifying uncertainties in geochemical sampling and analysis as a function of sample size and analyses and (ii) for determining the optimum sample size to ensure data quality. The statistical analysis approach was adopted as the best method for sample size determination. The approach is based on the premise that the size of the study sample is critical to producing meaningful results. The size of the required samples depends on a number of factors including purpose of the study, available budget, variability of the population being sampled, acceptable errors and confidence level. The methodology for estimating uncertainty is a fusion of existing methodologies for quantifying measurement uncertainty. The methodology takes a holistic view of the measurement process to include all processes involved in obtaining measurement results as possible uncertainty components. Like the statistical analysis approach, the methodology employs basic statistical principles in estimating the size of uncertainty, associated with a given measurement result. The approach identifies each component of uncertainty; estimates the size of each component and sums the contribution of each component in order to approximate the overall uncertainty value, associated with a given measurement result. The two methods were applied to Acid-Base Accounting (ABA) data derived from geochemical assessment for ERA of the West Wits and Vaal River (Ashanti Gold mines) tailings dams undertaken by Pulles and Howard de Lange Inc. on behalf of AngloGold Ltd. The study was aimed at assessing and evaluating the potential of tailings dams in the two mining areas to impact on water quality and implications of this in terms of mine closure and rehabilitation. Findings from this study show that the number of samples needed is influenced by the purpose of the study, size of the target area, nature and type of material, budget, acceptable error and the confidence level required, among other factors. Acceptable error has an exponential relationship with sample size hence one can minimize error by increasing sample size. While a low value of acceptable error value and high confidence are always desirable, a tradeoff among these competing factors must be found, given the usually limited funds and time. The findings also demonstrated that uncertainties in geochemical sampling and analysis are unavoidable. They arise from the fact that only a small portion of the population rather than a census is used to derive conclusions about certain characteristics of the target population. This is further augmented by other influential quantities that affect the accuracy of the estimates. Effects such as poor sampling design, inadequate sample size, sample heterogeneity and other factors highly affect data quality and representivity hence measurement uncertainty. Among these factors, those associated with sampling, mainly heterogeneity was found to be the strongest contributing factor toward overall uncertainty. This implies an increased proportion of expenditure should be channelled toward sampling to minimise uncertainty. Uncertainties can be reduced by adopting good sampling practices and increasing sample size, among other methods. It is recommended that more information be made available for proper uncertainty analysis. , Thesis (MSc) -- Faculty of Science and Agriculture, 2010
- Full Text:
- Date Issued: 2010-04
Evaluation and comparison of rural and industrial brick masonry units for sustainabile low cost housing
- Authors: Maweza, Elijah Loyiso
- Date: 2011-01
- Subjects: Masonry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24923 , vital:63676
- Description: The lack of adequate housing for the rural population of South Africa is experienced in every community. The South African government has drawn policies, strategies and required standards that must govern the provision of housing to the people. One of the required standards of housing is that the walls be constructed in such a way that they are able to adequately resist water penetration into any part of the building where it would be detrimental to the health of the occupants or the lifespan of the building. This research took the investigation of the characteristics of bricks that increase or reduce water absorption by bricks as the main objective. The investigation looked first at the raw materials of bricks, the soils and clay. The particle size related soil fractions were investigated because particle sizes are directly linked to the porosity of the bricks. Porosity describes the percentage of pores that are in the bricks, which show the extent to which bricks can internally accommodate moisture. Soil mineralogy was also discussed because as bricks are fired, the changes that they undergo affect the mineralogy of the bricks. The manufacturing procedures (brick moulding and firing) as reported from literature are briefly discussed in chapter 2. The effect of heat on clays is also discussed in order to explain the changes that occur as a result of firing. The porosity and the sorptivity of bricks were the relevant brick properties that are discussed. The methods employed to investigate the characteristics of bricks as discussed in chapter 3 were as follows: (i) Winning and preparation of raw materials. (ii) Particle size analysis. (iii) Water and carbon content in newly formed rural and industrial bricks. (iv) The firing procedures and temperature distribution investigation. (v) The chemical composition of rural and industrial bricks. (vi) Porosity. (vii) The Neutron Radiography equipment and operations. (viii) Sorptivity. With these investigations it was discovered that the quality of the bricks can be improved by: (i) Selecting and preparing the raw materials. This can be done by considering the soil types and reducing the soil particle sizes by sieving and grinding. (ii) Moulding the bricks properly by thoroughly working the soil, reducing the water content and increasing compaction. (iii) Drying the bricks using the sun and the exhaust heat from the kilns that are firing bricks at the time. (iv) Adopting brick firing techniques that produce the desired bricks more efficiently. , Thesis (MSc) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-01
- Authors: Maweza, Elijah Loyiso
- Date: 2011-01
- Subjects: Masonry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24923 , vital:63676
- Description: The lack of adequate housing for the rural population of South Africa is experienced in every community. The South African government has drawn policies, strategies and required standards that must govern the provision of housing to the people. One of the required standards of housing is that the walls be constructed in such a way that they are able to adequately resist water penetration into any part of the building where it would be detrimental to the health of the occupants or the lifespan of the building. This research took the investigation of the characteristics of bricks that increase or reduce water absorption by bricks as the main objective. The investigation looked first at the raw materials of bricks, the soils and clay. The particle size related soil fractions were investigated because particle sizes are directly linked to the porosity of the bricks. Porosity describes the percentage of pores that are in the bricks, which show the extent to which bricks can internally accommodate moisture. Soil mineralogy was also discussed because as bricks are fired, the changes that they undergo affect the mineralogy of the bricks. The manufacturing procedures (brick moulding and firing) as reported from literature are briefly discussed in chapter 2. The effect of heat on clays is also discussed in order to explain the changes that occur as a result of firing. The porosity and the sorptivity of bricks were the relevant brick properties that are discussed. The methods employed to investigate the characteristics of bricks as discussed in chapter 3 were as follows: (i) Winning and preparation of raw materials. (ii) Particle size analysis. (iii) Water and carbon content in newly formed rural and industrial bricks. (iv) The firing procedures and temperature distribution investigation. (v) The chemical composition of rural and industrial bricks. (vi) Porosity. (vii) The Neutron Radiography equipment and operations. (viii) Sorptivity. With these investigations it was discovered that the quality of the bricks can be improved by: (i) Selecting and preparing the raw materials. This can be done by considering the soil types and reducing the soil particle sizes by sieving and grinding. (ii) Moulding the bricks properly by thoroughly working the soil, reducing the water content and increasing compaction. (iii) Drying the bricks using the sun and the exhaust heat from the kilns that are firing bricks at the time. (iv) Adopting brick firing techniques that produce the desired bricks more efficiently. , Thesis (MSc) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-01
Functionalized Ru(II) polypyridines and phthalocyanines: Potential dyes for dye-sensitized solar cells(DSSCs)
- Adeloye, Adewale Olufunsho https://orcid.org/0000-0003-1736-5738
- Authors: Adeloye, Adewale Olufunsho https://orcid.org/0000-0003-1736-5738
- Date: 2011-01
- Subjects: Phthalocyanines , Dye-sensitized solar cells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24365 , vital:62645
- Description: This study describes the design, synthesis, characterization and preliminary investigation of the solar-to-electrical energy conversion efficiency of ruthenium(II) functionalized polypyridine and phthalocyanine complexes with extended π-conjugation. Polypyridinyl functionalized with anthracene, 2,3-dimethylacrylic acid and 1-methoxy-1-buten-3-yne were synthesized and characterized by infrared, UV-Vis, photoluminescence, 1H and 13C NMR and elemental analysis. The functionalized polypyridine molecules were used to synthesize various ruthenium(II) homoleptic/heteroleptic and/or heteronuclear complexes and their photophysical and electrochemical properties evaluated. The preliminary results of the solar-to-electrical conversion efficiencies of some synthesized Ru(II) polypyridyl complexes were presented in chapter 5. It was found out as expected that the ruthenium(II) polypyridine complexes containing either heteronuclear polypyridine ligands or their thiocyanate analogues of the types [Ru(L1)2L2(PF6)2], [RuL1(L2)2(PF6)2] and [RuL1L2(NCS)2], showed better photophysical properties (red-shifted metal-to-ligand charge-transfer (MLCT) transitions concomitant with enhanced molar extinction coefficients), luminescence and interesting electrochemical redox properties than those containing homonuclear ligand types [Ru(L1)3(PF6)2]. The ruthenium(II) anthracenyl functionalized phthalocyanine complexes which were obtained by electrophilic aromatic substitution reactions in the peripheral positions gave good solubility properties in various organic solvents and also showed interesting near infrared absorption and electroredox characteristics. Cyclic and square wave voltammetries of these complexes revealed major redox processes and the numbers of electron(s) transfer were determined by chronocoulometry. It was established that a mono- and/or multi-electronic transfer reactions can occur in the various ruthenium(II) complexes. The photophysical properties of some complexes showed them to be better and promising candidates in the design of chemosensors, organic light emitting diodes (OLEDs) and as photosensitizers, while their redox-active natures make them potential mediators in electron-transfer for various photochemical processes. However, due to low surface concentration and/or adsorption of some tested complexes on TiO2 semiconductor nanocrystalline particle, low currents were generated and the highest solar-to- electrical conversion efficiency recorded in this study was 0.10 percent. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-01
- Authors: Adeloye, Adewale Olufunsho https://orcid.org/0000-0003-1736-5738
- Date: 2011-01
- Subjects: Phthalocyanines , Dye-sensitized solar cells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24365 , vital:62645
- Description: This study describes the design, synthesis, characterization and preliminary investigation of the solar-to-electrical energy conversion efficiency of ruthenium(II) functionalized polypyridine and phthalocyanine complexes with extended π-conjugation. Polypyridinyl functionalized with anthracene, 2,3-dimethylacrylic acid and 1-methoxy-1-buten-3-yne were synthesized and characterized by infrared, UV-Vis, photoluminescence, 1H and 13C NMR and elemental analysis. The functionalized polypyridine molecules were used to synthesize various ruthenium(II) homoleptic/heteroleptic and/or heteronuclear complexes and their photophysical and electrochemical properties evaluated. The preliminary results of the solar-to-electrical conversion efficiencies of some synthesized Ru(II) polypyridyl complexes were presented in chapter 5. It was found out as expected that the ruthenium(II) polypyridine complexes containing either heteronuclear polypyridine ligands or their thiocyanate analogues of the types [Ru(L1)2L2(PF6)2], [RuL1(L2)2(PF6)2] and [RuL1L2(NCS)2], showed better photophysical properties (red-shifted metal-to-ligand charge-transfer (MLCT) transitions concomitant with enhanced molar extinction coefficients), luminescence and interesting electrochemical redox properties than those containing homonuclear ligand types [Ru(L1)3(PF6)2]. The ruthenium(II) anthracenyl functionalized phthalocyanine complexes which were obtained by electrophilic aromatic substitution reactions in the peripheral positions gave good solubility properties in various organic solvents and also showed interesting near infrared absorption and electroredox characteristics. Cyclic and square wave voltammetries of these complexes revealed major redox processes and the numbers of electron(s) transfer were determined by chronocoulometry. It was established that a mono- and/or multi-electronic transfer reactions can occur in the various ruthenium(II) complexes. The photophysical properties of some complexes showed them to be better and promising candidates in the design of chemosensors, organic light emitting diodes (OLEDs) and as photosensitizers, while their redox-active natures make them potential mediators in electron-transfer for various photochemical processes. However, due to low surface concentration and/or adsorption of some tested complexes on TiO2 semiconductor nanocrystalline particle, low currents were generated and the highest solar-to- electrical conversion efficiency recorded in this study was 0.10 percent. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-01
Functionalized Ru(II) polypyridines and phthalocyanines: Potential dyes for dye-sensitized solar cells(DSSCs)
- Adeloye, Adewale Olufunsho https://orcid.org/0000-0003-1736-5738
- Authors: Adeloye, Adewale Olufunsho https://orcid.org/0000-0003-1736-5738
- Date: 2011-01
- Subjects: Phthalocyanines , Dye-sensitized solar cells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24343 , vital:62638
- Description: This study describes the design, synthesis, characterization and preliminary investigation of the solar-to-electrical energy conversion efficiency of ruthenium(II) functionalized polypyridine and phthalocyanine complexes with extended π-conjugation. Polypyridinyl functionalized with anthracene, 2,3-dimethylacrylic acid and 1-methoxy-1-buten-3-yne were synthesized and characterized by infrared, UV-Vis, photoluminescence, 1H and 13C NMR and elemental analysis. The functionalized polypyridine molecules were used to synthesize various ruthenium(II) homoleptic/heteroleptic and/or heteronuclear complexes and their photophysical and electrochemical properties evaluated. The preliminary results of the solar-to-electrical conversion efficiencies of some synthesized Ru(II) polypyridyl complexes were presented in chapter 5. It was found out as expected that the ruthenium(II) polypyridine complexes containing either heteronuclear polypyridine ligands or their thiocyanate analogues of the types [Ru(L1)2L2(PF6)2], [RuL1(L2)2(PF6)2] and [RuL1L2(NCS)2], showed better photophysical properties (red-shifted metal-to-ligand charge-transfer (MLCT) transitions concomitant with enhanced molar extinction coefficients), luminescence and interesting electrochemical redox properties than those containing homonuclear ligand types [Ru(L1)3(PF6)2]. The ruthenium(II) anthracenyl functionalized phthalocyanine complexes which were obtained by electrophilic aromatic substitution reactions in the peripheral positions gave good solubility properties in various organic solvents and also showed interesting near infrared absorption and electroredox characteristics. Cyclic and square wave voltammetries of these complexes revealed major redox processes and the numbers of electron(s) transfer were determined by chronocoulometry. It was established that a mono- and/or multi-electronic transfer reactions can occur in the various ruthenium(II) complexes. The photophysical properties of some complexes showed them to be better and promising candidates in the design of chemosensors, organic light emitting diodes (OLEDs) and as photosensitizers, while their redox-active natures make them potential mediators in electron-transfer for various photochemical processes. However, due to low surface concentration and/or adsorption of some tested complexes on TiO2 semiconductor nanocrystalline particle, low currents were generated and the highest solar-to-electrical conversion efficiency recorded in this study was 0.10 percent. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-01
- Authors: Adeloye, Adewale Olufunsho https://orcid.org/0000-0003-1736-5738
- Date: 2011-01
- Subjects: Phthalocyanines , Dye-sensitized solar cells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24343 , vital:62638
- Description: This study describes the design, synthesis, characterization and preliminary investigation of the solar-to-electrical energy conversion efficiency of ruthenium(II) functionalized polypyridine and phthalocyanine complexes with extended π-conjugation. Polypyridinyl functionalized with anthracene, 2,3-dimethylacrylic acid and 1-methoxy-1-buten-3-yne were synthesized and characterized by infrared, UV-Vis, photoluminescence, 1H and 13C NMR and elemental analysis. The functionalized polypyridine molecules were used to synthesize various ruthenium(II) homoleptic/heteroleptic and/or heteronuclear complexes and their photophysical and electrochemical properties evaluated. The preliminary results of the solar-to-electrical conversion efficiencies of some synthesized Ru(II) polypyridyl complexes were presented in chapter 5. It was found out as expected that the ruthenium(II) polypyridine complexes containing either heteronuclear polypyridine ligands or their thiocyanate analogues of the types [Ru(L1)2L2(PF6)2], [RuL1(L2)2(PF6)2] and [RuL1L2(NCS)2], showed better photophysical properties (red-shifted metal-to-ligand charge-transfer (MLCT) transitions concomitant with enhanced molar extinction coefficients), luminescence and interesting electrochemical redox properties than those containing homonuclear ligand types [Ru(L1)3(PF6)2]. The ruthenium(II) anthracenyl functionalized phthalocyanine complexes which were obtained by electrophilic aromatic substitution reactions in the peripheral positions gave good solubility properties in various organic solvents and also showed interesting near infrared absorption and electroredox characteristics. Cyclic and square wave voltammetries of these complexes revealed major redox processes and the numbers of electron(s) transfer were determined by chronocoulometry. It was established that a mono- and/or multi-electronic transfer reactions can occur in the various ruthenium(II) complexes. The photophysical properties of some complexes showed them to be better and promising candidates in the design of chemosensors, organic light emitting diodes (OLEDs) and as photosensitizers, while their redox-active natures make them potential mediators in electron-transfer for various photochemical processes. However, due to low surface concentration and/or adsorption of some tested complexes on TiO2 semiconductor nanocrystalline particle, low currents were generated and the highest solar-to-electrical conversion efficiency recorded in this study was 0.10 percent. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-01
Studies on bioflocculants produced by three freshwater Actinomycetes (Streptomyces Sp.Gansen, Cellulomonas Sp,Bola and Brachybacterium Sp, UFH) isolated from Tyume river
- Authors: Oladele, Agunbiade M
- Date: 2011
- Subjects: Flocculation Streptomyces Gram-positive bacteria Actinobacteria
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/6550 , vital:30552
- Description: Several bacteria were isolated from the bottom sediments of Tyume River and investigated for bioflocculant production potentials. Kaolin clay suspension (4 g/l) was used to measure the flocculating activity and three of the positive isolates were identified by 16S rRNA gene nucleotide sequence analyses and the sequences deposited in GenBank as Streptomyces sp Gansen (accession number HQ537129), Brachybacterium sp UFH (accession number HQ537131.), and Cellulomonas sp Bola (accession number HQ537132). Streptomyces sp Gansen exhibited its maximum flocculating activity using lactose (85% activity), peptone (76.3% activity), Ca2+ as sole sources of carbon, nitrogen and cations respectively, and at a neutral pH of 7.0, while, the bioflocculant produced by Brachybacterium sp UFH with glucose, urea and Ca2+ as carbon, nitrogen and cations sources yielded 82% and 97% flocculation activity respectively at a neutral pH. Also, glucose (73.2% activity), ammonium chloride (78.2% activity) and Ca2+ resulted in optimal production of bioflocculant by Cellulomonas sp Bola, also at a neutral pH. Chemical analysis confirmed that bioflocculant produced by Streptomyces Gansen is a polysaccharide while Brachybacterium sp UFH and Cellulomonas sp Bola produces a glycoprotein compound. This freshwater actinomycetes appears to have a tremendous potential as sou rces of new bioflocculants.
- Full Text:
- Date Issued: 2011
- Authors: Oladele, Agunbiade M
- Date: 2011
- Subjects: Flocculation Streptomyces Gram-positive bacteria Actinobacteria
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/6550 , vital:30552
- Description: Several bacteria were isolated from the bottom sediments of Tyume River and investigated for bioflocculant production potentials. Kaolin clay suspension (4 g/l) was used to measure the flocculating activity and three of the positive isolates were identified by 16S rRNA gene nucleotide sequence analyses and the sequences deposited in GenBank as Streptomyces sp Gansen (accession number HQ537129), Brachybacterium sp UFH (accession number HQ537131.), and Cellulomonas sp Bola (accession number HQ537132). Streptomyces sp Gansen exhibited its maximum flocculating activity using lactose (85% activity), peptone (76.3% activity), Ca2+ as sole sources of carbon, nitrogen and cations respectively, and at a neutral pH of 7.0, while, the bioflocculant produced by Brachybacterium sp UFH with glucose, urea and Ca2+ as carbon, nitrogen and cations sources yielded 82% and 97% flocculation activity respectively at a neutral pH. Also, glucose (73.2% activity), ammonium chloride (78.2% activity) and Ca2+ resulted in optimal production of bioflocculant by Cellulomonas sp Bola, also at a neutral pH. Chemical analysis confirmed that bioflocculant produced by Streptomyces Gansen is a polysaccharide while Brachybacterium sp UFH and Cellulomonas sp Bola produces a glycoprotein compound. This freshwater actinomycetes appears to have a tremendous potential as sou rces of new bioflocculants.
- Full Text:
- Date Issued: 2011
The impact of HIV/AIDS on the delivery of maternal health care services of selected primary health care clinics of Peddie in the Eastern Cape Province
- Mangi, Nozuko Glenrose https://orcid.org/0000-0001-9158-8820
- Authors: Mangi, Nozuko Glenrose https://orcid.org/0000-0001-9158-8820
- Date: 2011
- Subjects: Maternal health services , Primary health care , HIV infections -- Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24576 , vital:63209
- Description: The aim of this descriptive study was to explore the impact of HIV/AIDS on the maternal health programme at selected Primary Health Care (PHC) clinics in the Peddie sub-district, in the Eastern Cape, South Africa. This study showed that the HIV/AIDS epidemic has had major influences on the rendering of maternal health services in this sub-district. An understanding of the impact of HIV/AIDS on the delivery of the maternal health programme in the Peddie Primary Health Clinics will potentially help the District Health Service office, as well as the clinic managers and professional nurses to formulate strategies to strengthen the maternal health programme. This data will also be helpful when developing plans to cope with the heavy work-load of the clinics offering maternal health services, and to address the attitudes and concerns of the professional nurses working in the PHC clinics in this area. Thirty professional nurses working at 10 clinics responded to the questionnaires which elicited questions pertaining to the impact of HIV/AIDS on the rendering of their services. As part of the data gathering procedures, standardised notice boards at the PHC clinics were used to document the services rendered. The numbers of ANC clients attended to each of the clinics per week were collected in routine attendance tick registers used in the clinics for recording and monitoring statistics in the maternal health programme. The data was analysed to examine the possible impact of HIV/AIDS on maternal health services rendered by registered nurses/midwives working in the PHC clinics. The registered nurses who responded to the questionnaires (Annexure H) made several suggestions. These included the following: (i) encouraged more training (11 nurses), (ii) addition of more staff members, (iii) to have specialized staff for management of maternal HIV. Because of the study limitations such as the sample size of 10 clinics with a total of 30 nurses who were studied, the study may not be generalised to the whole of the Eastern Cape Province. The study however did provide baseline information on the impact of HIV/AIDS on the maternal health programme. The study findings were that HIV/AIDS has had an impact on the delivery of the maternal health programme due to the extra services brought about by the response to the HIV/AIDS pandemic. This study will contribute to a better understanding of the impact of HIV/AIDS on the maternal health programme at the PHC level in Peddie. The research provided insight into issues that are crucial to the delivery of maternal health programmes in rural areas. , Thesis (MCur) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011
- Authors: Mangi, Nozuko Glenrose https://orcid.org/0000-0001-9158-8820
- Date: 2011
- Subjects: Maternal health services , Primary health care , HIV infections -- Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24576 , vital:63209
- Description: The aim of this descriptive study was to explore the impact of HIV/AIDS on the maternal health programme at selected Primary Health Care (PHC) clinics in the Peddie sub-district, in the Eastern Cape, South Africa. This study showed that the HIV/AIDS epidemic has had major influences on the rendering of maternal health services in this sub-district. An understanding of the impact of HIV/AIDS on the delivery of the maternal health programme in the Peddie Primary Health Clinics will potentially help the District Health Service office, as well as the clinic managers and professional nurses to formulate strategies to strengthen the maternal health programme. This data will also be helpful when developing plans to cope with the heavy work-load of the clinics offering maternal health services, and to address the attitudes and concerns of the professional nurses working in the PHC clinics in this area. Thirty professional nurses working at 10 clinics responded to the questionnaires which elicited questions pertaining to the impact of HIV/AIDS on the rendering of their services. As part of the data gathering procedures, standardised notice boards at the PHC clinics were used to document the services rendered. The numbers of ANC clients attended to each of the clinics per week were collected in routine attendance tick registers used in the clinics for recording and monitoring statistics in the maternal health programme. The data was analysed to examine the possible impact of HIV/AIDS on maternal health services rendered by registered nurses/midwives working in the PHC clinics. The registered nurses who responded to the questionnaires (Annexure H) made several suggestions. These included the following: (i) encouraged more training (11 nurses), (ii) addition of more staff members, (iii) to have specialized staff for management of maternal HIV. Because of the study limitations such as the sample size of 10 clinics with a total of 30 nurses who were studied, the study may not be generalised to the whole of the Eastern Cape Province. The study however did provide baseline information on the impact of HIV/AIDS on the maternal health programme. The study findings were that HIV/AIDS has had an impact on the delivery of the maternal health programme due to the extra services brought about by the response to the HIV/AIDS pandemic. This study will contribute to a better understanding of the impact of HIV/AIDS on the maternal health programme at the PHC level in Peddie. The research provided insight into issues that are crucial to the delivery of maternal health programmes in rural areas. , Thesis (MCur) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011
On the design, evaluation and performance of an energy efficient solar house with integrated photovoltaics
- Authors: Ziuku, Sosten
- Date: 2011-06
- Subjects: Solar energy , Solar energy -- Environmental aspects , Photovoltaic power generation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27473 , vital:67331
- Description: The design, construction and performance monitoring of an energy efficient house with integrated photovoltaics is considered. Unlike conventional housing, the house design combines energy efficiency measures and renewable energy technologies into one building structure. The objective of the study was to investigate the feasibility of using energy efficient solar designs to regulate indoor thermal environment, and determine thecost effectiveness and environmental benefits of such housing designs. The use of ordinary photovoltaic panels as a building element for South Africa’s latitude and meteorological conditions was also investigated. The house model was designed using Autodesk Revit architecture and Ecotect building simulation software. Electrical performance was analyzed using RETScreen and PVDesignPRO software. In addition to passive solar design features and clerestory windows, the design has solar water heaters for hot water supply. The designed energy efficient building integrated photovoltaic (EEBIPV) house was built at the University of Fort Hare. A 3.8 kW BIPV generator was mounted on the north facing roof in such a way that the solar panels replace conventional roofing material. A data acquisition system that monitors thermal and electrical performance was installed. The grid independent house has been occupied since February 2009 and its winter indoor thermal efficiency improved from 70 to more than 78% after ceiling installation. Models for indoor thermal performance and BIPV energy and exergy contributions were developed. The avoided energy consumption from the grid has potential to reduce carbon emissions by 12.41 tons per annum. The total building cost per m2 of floor area compares favourably with the cost of commercial middle-to-upper income domestic housing units without energy efficiency measures and building integrated photovoltaics. The research output provides a good framework for the integration of passive solar designs, natural ventilation and lighting, solar water heaters and building integrated photovoltaics into new and existing housing units. , Thesis (MSci) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-06
- Authors: Ziuku, Sosten
- Date: 2011-06
- Subjects: Solar energy , Solar energy -- Environmental aspects , Photovoltaic power generation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27473 , vital:67331
- Description: The design, construction and performance monitoring of an energy efficient house with integrated photovoltaics is considered. Unlike conventional housing, the house design combines energy efficiency measures and renewable energy technologies into one building structure. The objective of the study was to investigate the feasibility of using energy efficient solar designs to regulate indoor thermal environment, and determine thecost effectiveness and environmental benefits of such housing designs. The use of ordinary photovoltaic panels as a building element for South Africa’s latitude and meteorological conditions was also investigated. The house model was designed using Autodesk Revit architecture and Ecotect building simulation software. Electrical performance was analyzed using RETScreen and PVDesignPRO software. In addition to passive solar design features and clerestory windows, the design has solar water heaters for hot water supply. The designed energy efficient building integrated photovoltaic (EEBIPV) house was built at the University of Fort Hare. A 3.8 kW BIPV generator was mounted on the north facing roof in such a way that the solar panels replace conventional roofing material. A data acquisition system that monitors thermal and electrical performance was installed. The grid independent house has been occupied since February 2009 and its winter indoor thermal efficiency improved from 70 to more than 78% after ceiling installation. Models for indoor thermal performance and BIPV energy and exergy contributions were developed. The avoided energy consumption from the grid has potential to reduce carbon emissions by 12.41 tons per annum. The total building cost per m2 of floor area compares favourably with the cost of commercial middle-to-upper income domestic housing units without energy efficiency measures and building integrated photovoltaics. The research output provides a good framework for the integration of passive solar designs, natural ventilation and lighting, solar water heaters and building integrated photovoltaics into new and existing housing units. , Thesis (MSci) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-06
Medicinal properties of Moringa (Moringa Oleifera Lam) leaves and the effect of its use as a supplement on goat growth performance and meat characteristics
- Moyo, Busani https://orcid.org/0000-0001-7002-7266
- Authors: Moyo, Busani https://orcid.org/0000-0001-7002-7266
- Date: 2011-09
- Subjects: Moringa , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24376 , vital:62662
- Description: The main objective of the study was to determine if feeding goats with Moringa oleifera leaves would lead to an increase in productivity and in value of the meat. The proximate, van Soet, atomic absorption spectrophotometric and soxhlet extraction methods were used to determine the nutritional value M. oleifera leaves of the South African. The in-vitro antimicrobial screening methods were used to determine antimicrobial activities M. oleifera extracts while in vitro and invivo models were used to determine the antioxidant activities of M. oleifera leaves. An evaluation of the potential of M. oleifera leaf meal as a feed supplement in terms of its effect on helminth load, goat growth performance, carcass characteristics, meat quality attributes, nutritional and consumer sensory characteristics of goat meat was done. A total of 24, eight month old goats were randomly allocated to dietary treatments of M. oleifera leaf meal (MOL), sunflower seed cake (SC) and GH (grass hay) which was the control. All the groups were fed on basal diet of grass hay ad libitum and 200g wheat bran per head per day. The MOL group was given an additional 200 g of dried M. oleifera leaves while the SC group was offered 170 g sunflower seed cake per head/day. The study showed that the dried leaves had crude protein levels of 30.3 percent, polyunsaturated fatty acids (52.21 percent), Saturated fatty acids (43.31), n-3 (44.57 percent), n-6 (7.64 percent), 19 amino acids, vitamin E (77 mg/100 g) and Beta-carotene (18.5 mg/100 g). The M. oleifera leaf extracts showed antibacterial activities against Escherichia coli, Enterobacter cloace, Proteus vulgaris, Staphylococcus aureus and Micrococcus kristinae. The supplementation of goats with MOL and SC resulted in decreased feacal larval count and lower Haemonchus contortus, Trichostrongylus colubriforms and Oesophagastum columbianum worm burdens than those in the non-supplemented goats. Goats supplemented with SC and MOL had higher average daily weight gain and heavier carcasses than those in the GH group. Higher pH1 scores were observed in chevon from GH diet than the supplemented ones. The MOL and SC supplemented goats had chevon with higher values for lightness (L*) 24 hr post-mortem than the one from the GH group. The redness (a*) values of chevon 24 hr post mortem was highest in MOL supplemented goats. Warner Bratzler shear force (WBSF) values of SC (30.1 N) and MOL (29.8 N) supplemented goats were lower than those from GH diet (32.6 N). Chevon from goats fed GH diet had significantly higher cooking losses (29.5 percent) than that from MOL (25.4 percent) and SC (25.6 percent) fed groups. It was observed that chevon from MOL and SC supplemented groups had higher crude protein (23.57 and 22.95 percent, respectively) than the one from the GH group (21.20 percent). Cholesterol levels were higher in chevon from SC (42.84) supplemented goats than those from MOL (38.76) and GH (35.63 mg). Chevon from GH and MOL group had higher (P < 0.05) proportions of PUFA, n-3, PUFA/SFA ratio and lower n-6/n-3 ratio. Mean consumer scores for first bite, aroma, flavour and juiceness were higher in the MOL group than in the GH group (P < 0.05). The acetone extract exhibited higher concentrations of total flavonoids, flavonols, phenolics. The acetone extracts depicted higher percentage inhibition against DPPH, ABTS and nitric oxide radicals which were comparable with reference antioxidant (vitamin C and BHT). The M. oleifera leaf meal increased the antioxidant activity of GSH, SOD and catalase. Moringa oleifera leaves also exhibited medicinal properties by having anthelmintic, antibacterial activities and showed antioxidant properties. It was also observed that protein supplementation improved the animal growth performance, the physico-chemical characteristics, nutritional and fatty acids composition of meat hence meeting the consumer needs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-09
- Authors: Moyo, Busani https://orcid.org/0000-0001-7002-7266
- Date: 2011-09
- Subjects: Moringa , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24376 , vital:62662
- Description: The main objective of the study was to determine if feeding goats with Moringa oleifera leaves would lead to an increase in productivity and in value of the meat. The proximate, van Soet, atomic absorption spectrophotometric and soxhlet extraction methods were used to determine the nutritional value M. oleifera leaves of the South African. The in-vitro antimicrobial screening methods were used to determine antimicrobial activities M. oleifera extracts while in vitro and invivo models were used to determine the antioxidant activities of M. oleifera leaves. An evaluation of the potential of M. oleifera leaf meal as a feed supplement in terms of its effect on helminth load, goat growth performance, carcass characteristics, meat quality attributes, nutritional and consumer sensory characteristics of goat meat was done. A total of 24, eight month old goats were randomly allocated to dietary treatments of M. oleifera leaf meal (MOL), sunflower seed cake (SC) and GH (grass hay) which was the control. All the groups were fed on basal diet of grass hay ad libitum and 200g wheat bran per head per day. The MOL group was given an additional 200 g of dried M. oleifera leaves while the SC group was offered 170 g sunflower seed cake per head/day. The study showed that the dried leaves had crude protein levels of 30.3 percent, polyunsaturated fatty acids (52.21 percent), Saturated fatty acids (43.31), n-3 (44.57 percent), n-6 (7.64 percent), 19 amino acids, vitamin E (77 mg/100 g) and Beta-carotene (18.5 mg/100 g). The M. oleifera leaf extracts showed antibacterial activities against Escherichia coli, Enterobacter cloace, Proteus vulgaris, Staphylococcus aureus and Micrococcus kristinae. The supplementation of goats with MOL and SC resulted in decreased feacal larval count and lower Haemonchus contortus, Trichostrongylus colubriforms and Oesophagastum columbianum worm burdens than those in the non-supplemented goats. Goats supplemented with SC and MOL had higher average daily weight gain and heavier carcasses than those in the GH group. Higher pH1 scores were observed in chevon from GH diet than the supplemented ones. The MOL and SC supplemented goats had chevon with higher values for lightness (L*) 24 hr post-mortem than the one from the GH group. The redness (a*) values of chevon 24 hr post mortem was highest in MOL supplemented goats. Warner Bratzler shear force (WBSF) values of SC (30.1 N) and MOL (29.8 N) supplemented goats were lower than those from GH diet (32.6 N). Chevon from goats fed GH diet had significantly higher cooking losses (29.5 percent) than that from MOL (25.4 percent) and SC (25.6 percent) fed groups. It was observed that chevon from MOL and SC supplemented groups had higher crude protein (23.57 and 22.95 percent, respectively) than the one from the GH group (21.20 percent). Cholesterol levels were higher in chevon from SC (42.84) supplemented goats than those from MOL (38.76) and GH (35.63 mg). Chevon from GH and MOL group had higher (P < 0.05) proportions of PUFA, n-3, PUFA/SFA ratio and lower n-6/n-3 ratio. Mean consumer scores for first bite, aroma, flavour and juiceness were higher in the MOL group than in the GH group (P < 0.05). The acetone extract exhibited higher concentrations of total flavonoids, flavonols, phenolics. The acetone extracts depicted higher percentage inhibition against DPPH, ABTS and nitric oxide radicals which were comparable with reference antioxidant (vitamin C and BHT). The M. oleifera leaf meal increased the antioxidant activity of GSH, SOD and catalase. Moringa oleifera leaves also exhibited medicinal properties by having anthelmintic, antibacterial activities and showed antioxidant properties. It was also observed that protein supplementation improved the animal growth performance, the physico-chemical characteristics, nutritional and fatty acids composition of meat hence meeting the consumer needs. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-09
An evaluation of stress tolerant open pollinated maize varieties in selected environments of the Eastern Cape Province, South Africa
- Chimonyo, Vimbayi G P https://orcid.org/0000-0001-9912-9848
- Authors: Chimonyo, Vimbayi G P https://orcid.org/0000-0001-9912-9848
- Date: 2011-11
- Subjects: Crops -- Effect of stress on
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24487 , vital:63045
- Description: The use of farmer acceptable, stress tolerant open pollinated maize varieties (OPVs) could be a strategy to help increase maize productivity for resource-poor farmers in the Eastern Cape (EC) Province. The current study investigated the following: a) participatory selection of newly introduced stress tolerant maize OPVs; b) characteristics of maize producing farmers, their production constraints and criteria for variety selections; c) multi-environment yield trials in which genotype and environment interactions (GEI) were investigated, and d) morphological diversity of newly introduced maize varieties. Nine newly introduced maize OPVs were evaluated in this study. These varieties were: ZM 305, ZM 423 ZM 501, ZM 525, Obatanpa, ZM 621, ZM 627, which were from the International Maize and Wheat Improvement Centre (CIMMYT), BR 993, and Comp 4 which from where the International Institute of Tropical Agriculture (IITA). Check varieties, Pan 6479 (a hybrid) and three locally grown OPVs (Okavango, Afric 1 and Nelson‘s Choice) were also included. Participatory variety selection (PVS) was conducted during the 2009/10 summer season to evaluate farmer acceptance of these newly introduced OPVs. The most preferred varieties farmers were Okavango, ZM 305 and ZM 501, and these varieties were not significantly different from the highest yielding variety within each site. Therefore, varieties like ZM 305 and ZM 501 could easily be adopted by farmers, and their use could result in yield improvements. To gather information on farmer characteristics, and perceptions on maize production constraints and maize selection criteria, focus group discussions and household surveys were conducted during the 2009/2010 and 2010/2011 seasons, respectively. Results indicated that, elderly farmers dominated the farming communities. Maize production was generally low, with 98percent of the farmers obtaining less than 1.6 t/ha. The most important constraints affecting maize production were extreme weather events (floods and drought), pests and diseases, and poor access to credit. The most preferred traits that made up farmer selection criteria were ear traits such as taste, long cobs, and big kernels. Other traits, such as, prolificacy, early maturity, retainability of seed and dark leaves, were village specific. Yield trials, assessing genotype and environment interactions, were conducted in eight sites during the 2009/10 and 2010/11 seasons. The genotypes exhibited non-significant crossover and non-crossover GEI over the environments. Okavango, the most stable variety, was generally low yielding (4.28 t/ha) than other stable varieties such as ZM 305, ZM 501, ZM 621 and ZM 423. The later varieties had significantly (p<0.05) higher yields of between 4.46 t/ha and 4.97 t/ha. The highest yielding varieties, Pan 6479 (5.29 t/ha) and ZM 525 (4.87 t/ha), showed specific adaptations to high potential environments, while BR 993 (4.07 t/ha) and Afric 1 (4.24 t/ha) were low yielding, unstable and specifically adapted to low potential environments. New varieties, therefore, exhibited both specific and wide adaptation. Qualitative and quantitative traits were evaluated to establish the morphological diversity of the 13 varieties. Ear height, plant height, days to 50percent anthesis and grain yield contributed the most to variety diversity. Cluster Analysis discriminated varieties into four main clusters. The first cluster consisted of four CIMMYT varieties that were short in height and early maturing (ZM 305, ZM 423, ZM 501 and ZM 525), while hybrid Pan 6479 was placed into cluster two. Nelson‘s Choice and Okavango were grouped into the third cluster, while tall and late maturing varieties, ZM 621, ZM 627, Obatanpa, BR 993, Comp 4 and Afric 1, were placed in the fourth cluster. The segregation of the newly introduced varieties into two distinct groups shows that these varieties can be recommended into more than on cropping system and agro-ecology. Differences in village agro-ecologies resulted in farmers selecting varieties differently. This diversity in agro-ecology also brought about variations on farmer perceptions in selection criteria and production constraints. Most of the new varieties were observed to be superior in yield performance when compared to local check OPVs, exhibiting either wide or specific adaptation. The study also demonstrated that, the study of morphological diversity can be used to suggest varieties to different environmental potentials and cropping systems. Multi-evaluation trials were able to give an insight on variety preferences and performance. These new varieties should, therefore, be introduced to selected farmers living in their respective environments on the basis of results obtained. However, varieties still need to be evaluated under farmer-managed conditions to determine whether they actually bring about yield improvement when compared with current varieties being used. , Thesis (MSc) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-11
- Authors: Chimonyo, Vimbayi G P https://orcid.org/0000-0001-9912-9848
- Date: 2011-11
- Subjects: Crops -- Effect of stress on
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24487 , vital:63045
- Description: The use of farmer acceptable, stress tolerant open pollinated maize varieties (OPVs) could be a strategy to help increase maize productivity for resource-poor farmers in the Eastern Cape (EC) Province. The current study investigated the following: a) participatory selection of newly introduced stress tolerant maize OPVs; b) characteristics of maize producing farmers, their production constraints and criteria for variety selections; c) multi-environment yield trials in which genotype and environment interactions (GEI) were investigated, and d) morphological diversity of newly introduced maize varieties. Nine newly introduced maize OPVs were evaluated in this study. These varieties were: ZM 305, ZM 423 ZM 501, ZM 525, Obatanpa, ZM 621, ZM 627, which were from the International Maize and Wheat Improvement Centre (CIMMYT), BR 993, and Comp 4 which from where the International Institute of Tropical Agriculture (IITA). Check varieties, Pan 6479 (a hybrid) and three locally grown OPVs (Okavango, Afric 1 and Nelson‘s Choice) were also included. Participatory variety selection (PVS) was conducted during the 2009/10 summer season to evaluate farmer acceptance of these newly introduced OPVs. The most preferred varieties farmers were Okavango, ZM 305 and ZM 501, and these varieties were not significantly different from the highest yielding variety within each site. Therefore, varieties like ZM 305 and ZM 501 could easily be adopted by farmers, and their use could result in yield improvements. To gather information on farmer characteristics, and perceptions on maize production constraints and maize selection criteria, focus group discussions and household surveys were conducted during the 2009/2010 and 2010/2011 seasons, respectively. Results indicated that, elderly farmers dominated the farming communities. Maize production was generally low, with 98percent of the farmers obtaining less than 1.6 t/ha. The most important constraints affecting maize production were extreme weather events (floods and drought), pests and diseases, and poor access to credit. The most preferred traits that made up farmer selection criteria were ear traits such as taste, long cobs, and big kernels. Other traits, such as, prolificacy, early maturity, retainability of seed and dark leaves, were village specific. Yield trials, assessing genotype and environment interactions, were conducted in eight sites during the 2009/10 and 2010/11 seasons. The genotypes exhibited non-significant crossover and non-crossover GEI over the environments. Okavango, the most stable variety, was generally low yielding (4.28 t/ha) than other stable varieties such as ZM 305, ZM 501, ZM 621 and ZM 423. The later varieties had significantly (p<0.05) higher yields of between 4.46 t/ha and 4.97 t/ha. The highest yielding varieties, Pan 6479 (5.29 t/ha) and ZM 525 (4.87 t/ha), showed specific adaptations to high potential environments, while BR 993 (4.07 t/ha) and Afric 1 (4.24 t/ha) were low yielding, unstable and specifically adapted to low potential environments. New varieties, therefore, exhibited both specific and wide adaptation. Qualitative and quantitative traits were evaluated to establish the morphological diversity of the 13 varieties. Ear height, plant height, days to 50percent anthesis and grain yield contributed the most to variety diversity. Cluster Analysis discriminated varieties into four main clusters. The first cluster consisted of four CIMMYT varieties that were short in height and early maturing (ZM 305, ZM 423, ZM 501 and ZM 525), while hybrid Pan 6479 was placed into cluster two. Nelson‘s Choice and Okavango were grouped into the third cluster, while tall and late maturing varieties, ZM 621, ZM 627, Obatanpa, BR 993, Comp 4 and Afric 1, were placed in the fourth cluster. The segregation of the newly introduced varieties into two distinct groups shows that these varieties can be recommended into more than on cropping system and agro-ecology. Differences in village agro-ecologies resulted in farmers selecting varieties differently. This diversity in agro-ecology also brought about variations on farmer perceptions in selection criteria and production constraints. Most of the new varieties were observed to be superior in yield performance when compared to local check OPVs, exhibiting either wide or specific adaptation. The study also demonstrated that, the study of morphological diversity can be used to suggest varieties to different environmental potentials and cropping systems. Multi-evaluation trials were able to give an insight on variety preferences and performance. These new varieties should, therefore, be introduced to selected farmers living in their respective environments on the basis of results obtained. However, varieties still need to be evaluated under farmer-managed conditions to determine whether they actually bring about yield improvement when compared with current varieties being used. , Thesis (MSc) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-11
The string vibrator experiment-experimental and analytical determination of system fundamental natural frequencies
- Authors: Gordon, Mark Leonard
- Date: 2011-11
- Subjects: Vibration , Nonlinear oscillations , Waves
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24002 , vital:62245
- Description: This thesis represents an experimental and intellectual journey of more than three years. The String Vibrator Experiment (SVE) is an experimental payload on the SumbandilaSat, satellite. The experiment was initially designed to compare low-earthorbitstretched string nonlinear dynamics with those found terrestrially, with particular emphasis on the effects of micro-gravity and near vacuum. Due to the damage of some internal components of the SVE, the terrestrial experiment had to be characterized by finding both transverse fundamental natural frequencies and the longitudinal system fundamental natural frequency. Forced and free vibration tests were performed on the SVE, with comparable results. The percentage frequency difference between measurement results obtained for the said natural frequencies was found to be acceptable. An analytical model for the string longitudinal system was developed using Energy Methods, assuming linear coupling of the stretched string and the flexible support. Bessel Functions were used to find the natural frequency of the flexible support, which is made of a thin-circular plate loaded centrally by the stretched string and fixed on its outer boundary. The natural frequency thus predicted, corresponds closely with that measured by Laser Doppler Vibrometry. It was found that the longitudinal system behaves in an uncoupled, manner. In this study use was made of piezo bi-morph sensors as vibration measuring devices, with promising results. A method called the peak amplitude discrimination method is introduced to find the respective resonant frequencies; this method is an adaptation of the sweptsine frequency method Nonlinear behavior of the SVE was found to exist exhibiting Sub-harmonics, Super-harmonics, Combination harmonics and Internal Resonances. It is hoped that the experimental methods used in this study would aid in the measurement and analysis of longitudinal vibrations found in flexible cables, rods and rigid bars. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-11
- Authors: Gordon, Mark Leonard
- Date: 2011-11
- Subjects: Vibration , Nonlinear oscillations , Waves
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24002 , vital:62245
- Description: This thesis represents an experimental and intellectual journey of more than three years. The String Vibrator Experiment (SVE) is an experimental payload on the SumbandilaSat, satellite. The experiment was initially designed to compare low-earthorbitstretched string nonlinear dynamics with those found terrestrially, with particular emphasis on the effects of micro-gravity and near vacuum. Due to the damage of some internal components of the SVE, the terrestrial experiment had to be characterized by finding both transverse fundamental natural frequencies and the longitudinal system fundamental natural frequency. Forced and free vibration tests were performed on the SVE, with comparable results. The percentage frequency difference between measurement results obtained for the said natural frequencies was found to be acceptable. An analytical model for the string longitudinal system was developed using Energy Methods, assuming linear coupling of the stretched string and the flexible support. Bessel Functions were used to find the natural frequency of the flexible support, which is made of a thin-circular plate loaded centrally by the stretched string and fixed on its outer boundary. The natural frequency thus predicted, corresponds closely with that measured by Laser Doppler Vibrometry. It was found that the longitudinal system behaves in an uncoupled, manner. In this study use was made of piezo bi-morph sensors as vibration measuring devices, with promising results. A method called the peak amplitude discrimination method is introduced to find the respective resonant frequencies; this method is an adaptation of the sweptsine frequency method Nonlinear behavior of the SVE was found to exist exhibiting Sub-harmonics, Super-harmonics, Combination harmonics and Internal Resonances. It is hoped that the experimental methods used in this study would aid in the measurement and analysis of longitudinal vibrations found in flexible cables, rods and rigid bars. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-11
Characterisation of communal rangeland degradation and evaluation of vegetation restoration techniques in the Eastern Cape, South Africa
- Authors: Lesoli, 'Mota Samuel
- Date: 2011-12
- Subjects: Communal rangelands , Grazing
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24316 , vital:62624
- Description: This study assessed the social factors influencing poor communal rangeland management, which are assumed to result in rangeland degradation. This was followed by, examination of biophysical characteristics of rangeland degradation in communal areas. To relate social factors featuring in communal rangeland management with rangeland degradation, biophysical factors influencing livestock grazing distribution patterns were studied. To establish the solution to communal rangeland degradation, rangeland restoration techniques were evaluated. The study was conducted at Amakhuze Tribal Authority (ATA) (S32o 38´, E26o56, 763 - 1500 m.a.s.l) composed of six villages and Phandulwazi Agricultural High School (S32o 39´ and E26o 55´, 747 m.a.s.l). Focus group discussions were conducted in six villages and questionnaire surveys in four randomly selected villages to assess social factors influencing communal rangeland degradation. Communal rangeland degradation biophysical characteristics were assessed. Biophysical factors affecting livestock grazing distribution pattern were examined through direct field observations for 12 months. Restoration techniques were evaluated on 26 plots. The social factors influencing communal rangeland management include lack of skills on rangeland management for farmers, lack of individual/community obligation on grazing management, lack of effective policies and/or poor enforcement accompanied by lack of effective institutions governing rangeland utilisation and management. Communal rangelands were more (χ 2 = 2612.07, df = 26, p < 0.01) degraded compared with controlled grazing areas. Within the communal rangelands, land degradation was higher at the low-lying areas, compared to foothills, midslopes, and mountaintop (crest). Rangeland degradation in communal areas was characterised by poor forage productivity and poor vegetation cover , higher soil unconfined compressive strength (UCS) (4.5 kg/cm2) with low hydraulic conductivity (5.21 x 10-3) and physical soil loss characteristics such presence of terracettes, pedestals, rills and gullies. Grazing distribution was higher at valley bottom (r2 = 0.404, p < 0.001), low altitude (r2 = -0.007, p < 0.001), closer to water points (r2 = -0.001, p < 0.001), and on grassland vegetation (r2 = 0.620, p < 0.001). Introduction of seedlings with microcatchment combined with brushpack promoted (p < 0.05) higher number of tillers (13), leaves (42) and reduced seedling mortality (10.4percent). T. triandra produced higher (p < 0.05) number of tillers (12) and leaves (39) but low number of inflorescence (0.7) with higher mortality rates (25.3percent) compared to P. dilatatum. Where plant propagules were introduced as seeds, use of microcatchment promoted higher seed germination (F = 38.84, p < 0.05) and maintained higher plant density (F = 37.43, p < 0.05). E. curvula seeds attained higher germination rate and maintained higher plant density compared to D. eriantha and P. Maximum. Use of microcatchment, brushpack, and water spreading system promoted soil water retention. It is important that any interventions aimed at improving communal rangeland management, controlling rangeland degradation in the communal areas, or restoring degraded rangelands to consider the social factors driving rangeland management and biophysical factors influencing grazing distribution pattern. Rangeland restoration techniques for communal areas should be centred on their ability to collect and retain water to promote restoration performance of introduced plant propagules. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-12
- Authors: Lesoli, 'Mota Samuel
- Date: 2011-12
- Subjects: Communal rangelands , Grazing
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24316 , vital:62624
- Description: This study assessed the social factors influencing poor communal rangeland management, which are assumed to result in rangeland degradation. This was followed by, examination of biophysical characteristics of rangeland degradation in communal areas. To relate social factors featuring in communal rangeland management with rangeland degradation, biophysical factors influencing livestock grazing distribution patterns were studied. To establish the solution to communal rangeland degradation, rangeland restoration techniques were evaluated. The study was conducted at Amakhuze Tribal Authority (ATA) (S32o 38´, E26o56, 763 - 1500 m.a.s.l) composed of six villages and Phandulwazi Agricultural High School (S32o 39´ and E26o 55´, 747 m.a.s.l). Focus group discussions were conducted in six villages and questionnaire surveys in four randomly selected villages to assess social factors influencing communal rangeland degradation. Communal rangeland degradation biophysical characteristics were assessed. Biophysical factors affecting livestock grazing distribution pattern were examined through direct field observations for 12 months. Restoration techniques were evaluated on 26 plots. The social factors influencing communal rangeland management include lack of skills on rangeland management for farmers, lack of individual/community obligation on grazing management, lack of effective policies and/or poor enforcement accompanied by lack of effective institutions governing rangeland utilisation and management. Communal rangelands were more (χ 2 = 2612.07, df = 26, p < 0.01) degraded compared with controlled grazing areas. Within the communal rangelands, land degradation was higher at the low-lying areas, compared to foothills, midslopes, and mountaintop (crest). Rangeland degradation in communal areas was characterised by poor forage productivity and poor vegetation cover , higher soil unconfined compressive strength (UCS) (4.5 kg/cm2) with low hydraulic conductivity (5.21 x 10-3) and physical soil loss characteristics such presence of terracettes, pedestals, rills and gullies. Grazing distribution was higher at valley bottom (r2 = 0.404, p < 0.001), low altitude (r2 = -0.007, p < 0.001), closer to water points (r2 = -0.001, p < 0.001), and on grassland vegetation (r2 = 0.620, p < 0.001). Introduction of seedlings with microcatchment combined with brushpack promoted (p < 0.05) higher number of tillers (13), leaves (42) and reduced seedling mortality (10.4percent). T. triandra produced higher (p < 0.05) number of tillers (12) and leaves (39) but low number of inflorescence (0.7) with higher mortality rates (25.3percent) compared to P. dilatatum. Where plant propagules were introduced as seeds, use of microcatchment promoted higher seed germination (F = 38.84, p < 0.05) and maintained higher plant density (F = 37.43, p < 0.05). E. curvula seeds attained higher germination rate and maintained higher plant density compared to D. eriantha and P. Maximum. Use of microcatchment, brushpack, and water spreading system promoted soil water retention. It is important that any interventions aimed at improving communal rangeland management, controlling rangeland degradation in the communal areas, or restoring degraded rangelands to consider the social factors driving rangeland management and biophysical factors influencing grazing distribution pattern. Rangeland restoration techniques for communal areas should be centred on their ability to collect and retain water to promote restoration performance of introduced plant propagules. , Thesis (PhD) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Date Issued: 2011-12