Petrophysical analysis of thermo-tectonic effects linked to Lower Jurassic dolerite intrusions in sedimentary rocks of the Main Karoo Basin, with implications for shale gas development in South Africa
- Authors: Nengovhela, Vhuhwavhohau
- Date: 2018
- Subjects: Sedimentary rocks -- South Africa -- Research , Sedimentation and deposition Geology, Structural -- South Africa Geology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33802 , vital:33034
- Description: Prevalent dolerite sills and dikes emplaced in the sedimentary rocks of the main Karoo Basin are associated with contact metamorphism and devolatilization of carbon-rich shales of the Lower Ecca Formation. These thermal effects may have significant bearings on the potential of shale gas development in the Karoo. This research aims to study and quantify the effects of dolerite intrusions on the Karoo sedimentary rocks along contact aureoles in shales and sandstones of the Ecca Group based on drill core samples collected from deep SOEKOR boreholes, and field samples from the Lower Beaufort Group of the Eastern Cape Province. Variations in host rock minerals, chemistry, and porosity are determined using analytical techniques including: petrography, scanning electron microscopy (SEM), X-ray diffraction (XRD) on samples collected along the thermal aureoles at various distances away from the intrusions. Using the determined mineral phase equilibria, geochemistry and thermal modelling, the pressure-temperature (P/T) conditions that prevailed during contact metamorphism are evaluated to constrain the thickness of the contact aureoles in deep boreholes, and to further evaluate potential loss of shale gas. The mineral composition of the samples generally consists of quartz, feldspar, illite/smectite, calcite, muscovite, and pyrite. Metamorphic minerals close to contacts with the sills include andalusite-chiastolite, biotite, muscovite, illite, forsterite, and diopside. SEM imaging confirms that the hornfels samples are compact and that the metamorphic minerals reduce and limit porosity to grain boundaries, and in few cases intra-mineral porosity occurs within individual crystals. The porosities are in the range of mesopores (2-50 nm) and micropores (< 2 nm). The data also suggests that the thermal alteration of the Ecca shales were short lived (e.g. 10-100 years). Disequilibrium metamorphic textures such as irregular grain boundaries, and inclusions in andalusite and cordierite confirm that the elevated temperatures did not last long enough to accomplish (re)crystallization and create equilibrium textures. To test the effect of geothermal gradients on the initial host rock temperatures prior to intrusive activity, and how these temperature differences affect the contact aureole thickness, thermal models were simulated for the deep boreholes using three geothermal gradients: 30 ◦C/km, 35 ◦C/km, and 40 ◦C/km. In addition, the depths were re-calculated based on post-emplacement erosion of the overlying host rocks (2000-3000 m). Heat flow away from dolerite sills through the host shales were modelled using convection and conduction heat flow mechanism separately, to assess differences and/or similarities in cooling trends. The models show that a 10 ◦C increase in geothermal gradient (from 30 ◦C /km to 40 ◦C/km) significantly affects the initial temperature of the host rocks and in turn decreases the rate at which the dolerite sills cool. Thermal modeling data is coherent with the mineralogy of the contact zones. Andalusitechiastolite and cordierite porphyroblasts occur within 10-20 m of the contact aureole, together with biotite and authigenic muscovite. Literature data shows that crystallization of this mineral assemblage in pelitic hornfels occurs at temperatures ranging between 450 ◦C and 600 ◦C. Thermal modelling results indicate maximum temperatures of shales at the contact with dolerite sills range between 650 ◦C to 700 ◦C. Temperatures decrease rapidly to approximately 400 ◦C within 10-20 m away from the contacts. The data also shows that thermal perturbation flanking the sills were short-lived, with maximum temperatures reached within the first 100 years of cooling depending on the thickness of dolerite sills and the combined effect of multiple sill intrusions. Data acquired from the thermal models and literature was used to evaluate gas loss estimations. The calculations conducted around a 45 m thick sill, suggests that at least 4- 6 TCF of gas was liberated from the Whitehill Formation during Karoo sill emplacement. These values are significantly less than previously calculated losses (22 TCF), and thus have a significant bearing on further predictions of shale gas potential of the Karoo Basin.
- Full Text:
- Date Issued: 2018
- Authors: Nengovhela, Vhuhwavhohau
- Date: 2018
- Subjects: Sedimentary rocks -- South Africa -- Research , Sedimentation and deposition Geology, Structural -- South Africa Geology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33802 , vital:33034
- Description: Prevalent dolerite sills and dikes emplaced in the sedimentary rocks of the main Karoo Basin are associated with contact metamorphism and devolatilization of carbon-rich shales of the Lower Ecca Formation. These thermal effects may have significant bearings on the potential of shale gas development in the Karoo. This research aims to study and quantify the effects of dolerite intrusions on the Karoo sedimentary rocks along contact aureoles in shales and sandstones of the Ecca Group based on drill core samples collected from deep SOEKOR boreholes, and field samples from the Lower Beaufort Group of the Eastern Cape Province. Variations in host rock minerals, chemistry, and porosity are determined using analytical techniques including: petrography, scanning electron microscopy (SEM), X-ray diffraction (XRD) on samples collected along the thermal aureoles at various distances away from the intrusions. Using the determined mineral phase equilibria, geochemistry and thermal modelling, the pressure-temperature (P/T) conditions that prevailed during contact metamorphism are evaluated to constrain the thickness of the contact aureoles in deep boreholes, and to further evaluate potential loss of shale gas. The mineral composition of the samples generally consists of quartz, feldspar, illite/smectite, calcite, muscovite, and pyrite. Metamorphic minerals close to contacts with the sills include andalusite-chiastolite, biotite, muscovite, illite, forsterite, and diopside. SEM imaging confirms that the hornfels samples are compact and that the metamorphic minerals reduce and limit porosity to grain boundaries, and in few cases intra-mineral porosity occurs within individual crystals. The porosities are in the range of mesopores (2-50 nm) and micropores (< 2 nm). The data also suggests that the thermal alteration of the Ecca shales were short lived (e.g. 10-100 years). Disequilibrium metamorphic textures such as irregular grain boundaries, and inclusions in andalusite and cordierite confirm that the elevated temperatures did not last long enough to accomplish (re)crystallization and create equilibrium textures. To test the effect of geothermal gradients on the initial host rock temperatures prior to intrusive activity, and how these temperature differences affect the contact aureole thickness, thermal models were simulated for the deep boreholes using three geothermal gradients: 30 ◦C/km, 35 ◦C/km, and 40 ◦C/km. In addition, the depths were re-calculated based on post-emplacement erosion of the overlying host rocks (2000-3000 m). Heat flow away from dolerite sills through the host shales were modelled using convection and conduction heat flow mechanism separately, to assess differences and/or similarities in cooling trends. The models show that a 10 ◦C increase in geothermal gradient (from 30 ◦C /km to 40 ◦C/km) significantly affects the initial temperature of the host rocks and in turn decreases the rate at which the dolerite sills cool. Thermal modeling data is coherent with the mineralogy of the contact zones. Andalusitechiastolite and cordierite porphyroblasts occur within 10-20 m of the contact aureole, together with biotite and authigenic muscovite. Literature data shows that crystallization of this mineral assemblage in pelitic hornfels occurs at temperatures ranging between 450 ◦C and 600 ◦C. Thermal modelling results indicate maximum temperatures of shales at the contact with dolerite sills range between 650 ◦C to 700 ◦C. Temperatures decrease rapidly to approximately 400 ◦C within 10-20 m away from the contacts. The data also shows that thermal perturbation flanking the sills were short-lived, with maximum temperatures reached within the first 100 years of cooling depending on the thickness of dolerite sills and the combined effect of multiple sill intrusions. Data acquired from the thermal models and literature was used to evaluate gas loss estimations. The calculations conducted around a 45 m thick sill, suggests that at least 4- 6 TCF of gas was liberated from the Whitehill Formation during Karoo sill emplacement. These values are significantly less than previously calculated losses (22 TCF), and thus have a significant bearing on further predictions of shale gas potential of the Karoo Basin.
- Full Text:
- Date Issued: 2018
Strength and conditioning practices of high school rugby coaches: a South African context
- Authors: Robinson, Bradley Charles
- Date: 2018
- Subjects: Rugby football coaches South Africa , Rugby football Coaching , Rugby football Physiological aspects , Rugby football Training , High school students Social conditions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63459 , vital:28413
- Description: Although the sport of rugby union is well established, the strength and conditioning practices of high school level players are not well known. Therefore, the purpose of this study was to examine the current strength and conditioning practices that coaches implement at South African high school level rugby. A secondary purpose was to compare practices between different types of schooling systems available in South Africa. An online survey or in person interview (depending on the school), adapted from previous strength and conditioning questionnaires, was conducted with 43 responses; including 28 schools among the top 100 rugby schools in South Africa for 2016 and 15 no-fee paying public schools in the Eastern Cape Province of South Africa. Results indicated that the top 100 rugby schools implement conditioning practices similar to the best-known international practices compared to no-fee paying schools who lacked the knowledge and skills in various strength and conditioning principles. It was found that all no-fee paying school coaches had insufficient qualifications to administer the correct training techniques. Coaches at all schools lacked the appropriate knowledge on injury prevention and scientifically based training programmes. It was concluded that education and skills around the best strength and conditioning practices for school level coaches needs to be improved and particularly in less privileged schools. The main goal being to reduce the risk of injury and improve performance across all sectors of the rugby playing population within the country. This was deemed crucial to the transformation goals set out by the South African Rugby Union, which would benefit from player development in lower socioeconomic schools.
- Full Text:
- Date Issued: 2018
- Authors: Robinson, Bradley Charles
- Date: 2018
- Subjects: Rugby football coaches South Africa , Rugby football Coaching , Rugby football Physiological aspects , Rugby football Training , High school students Social conditions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63459 , vital:28413
- Description: Although the sport of rugby union is well established, the strength and conditioning practices of high school level players are not well known. Therefore, the purpose of this study was to examine the current strength and conditioning practices that coaches implement at South African high school level rugby. A secondary purpose was to compare practices between different types of schooling systems available in South Africa. An online survey or in person interview (depending on the school), adapted from previous strength and conditioning questionnaires, was conducted with 43 responses; including 28 schools among the top 100 rugby schools in South Africa for 2016 and 15 no-fee paying public schools in the Eastern Cape Province of South Africa. Results indicated that the top 100 rugby schools implement conditioning practices similar to the best-known international practices compared to no-fee paying schools who lacked the knowledge and skills in various strength and conditioning principles. It was found that all no-fee paying school coaches had insufficient qualifications to administer the correct training techniques. Coaches at all schools lacked the appropriate knowledge on injury prevention and scientifically based training programmes. It was concluded that education and skills around the best strength and conditioning practices for school level coaches needs to be improved and particularly in less privileged schools. The main goal being to reduce the risk of injury and improve performance across all sectors of the rugby playing population within the country. This was deemed crucial to the transformation goals set out by the South African Rugby Union, which would benefit from player development in lower socioeconomic schools.
- Full Text:
- Date Issued: 2018
The evaluation of potential dietary media, measurement parameters and storage techniques for use in forensic entomotoxicology
- Mbatha, Erica Isabel Tavares Da Silva
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
Grapple cable yarding: a productivity model for fast-growing tree plantations in Sarawak, Malaysia
- Authors: Engelbrecht, Riaan
- Date: 2018
- Subjects: Tree farms -- Malaysia -- Sarawak , Forests and forestry -- Malaysia -- Sarawak Forest productivity -- Malaysia -- Sarawak
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22049 , vital:29816
- Description: Today, the two most important tasks faced by harvesting foresters and contractors are selecting the equipment and systems best suited to the site, and then to use this equipment in the best way possible (MacDonald, 1999). Experts estimate that the importance of tree plantations will continue to grow and that by 2050 75 per cent of the global fibre supply will be sourced from dedicated plantations (Ragauskas et al., 2006). To meet this growing demand plantations will most likely expand to steep slopes due to the priority given to agricultural and urban development, on flat land. New technological advancements in both cable yarding and ground-based harvesting systems has to a certain extent provided forest engineers with more options to choose from. Whether considering these options individually or in combination, they will have to make good choices in order to realise the full potential of forest plantations. One of the most promising techniques consist of an excavator-based unguyed yarder equipped with a new radio-controlled grapple carriage, fed by another excavator stationed on the cut-over. This system is very productive, avoids in-stand traffic and removes operators from positions of high risk. This long-term study was conducted on 12 different teams equipped with the new technology, operating in the fast-growing Acacia mangium plantations of Sarawak, Malaysia. Data were collected continuously for almost 8 months and represented 555 shifts, or over 55,000 yarding cycles - each recorded individually. This large data pool allowed for the development of robust models for system production, utilization and availability estimated respectively at: 63 m3 per productive machine hour (excluding all delays), 63 per cent and 93 per cent. The study also determined the effects of yarder type and team competence on productivity and utilization. Regression analysis of experimental data yielded a strong productivity forecast model that was highly significant, which accounted for 50 per cent of the total variability in the dataset and was validated with a non-significant error estimated at less than 1 per cent. The models reported in this study are especially robust, because they were obtained from a long-term study that covered multiple teams and accumulated an exceptionally large number of observations. While gained specifically on one yarder make (Alpine Yarder) and a specific plantation type (Acacia mangium), the information in this study can be extended to other similar machines and plantations, because the sheer volume of data allows cautious generalization. The teachings of kaizen, which suggest small-step work improvements, was adopted in order to propose the process of possible improvements, by combining elements of other harvesting systems as shown in Figure 1 below (Vorn Industries, 2017). Forestry is essentially a problem of transportation (Schenck, 1911) and the efficiency of such a transportation system will ultimately be determined by technology developments which drive system productivity (Ger & Klvac, 2014). Therefore, when we talk about systems for the future we should view them not as predictions or as prescriptions but as options that may be selected or rejected (Wood, 1979).
- Full Text:
- Date Issued: 2018
- Authors: Engelbrecht, Riaan
- Date: 2018
- Subjects: Tree farms -- Malaysia -- Sarawak , Forests and forestry -- Malaysia -- Sarawak Forest productivity -- Malaysia -- Sarawak
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22049 , vital:29816
- Description: Today, the two most important tasks faced by harvesting foresters and contractors are selecting the equipment and systems best suited to the site, and then to use this equipment in the best way possible (MacDonald, 1999). Experts estimate that the importance of tree plantations will continue to grow and that by 2050 75 per cent of the global fibre supply will be sourced from dedicated plantations (Ragauskas et al., 2006). To meet this growing demand plantations will most likely expand to steep slopes due to the priority given to agricultural and urban development, on flat land. New technological advancements in both cable yarding and ground-based harvesting systems has to a certain extent provided forest engineers with more options to choose from. Whether considering these options individually or in combination, they will have to make good choices in order to realise the full potential of forest plantations. One of the most promising techniques consist of an excavator-based unguyed yarder equipped with a new radio-controlled grapple carriage, fed by another excavator stationed on the cut-over. This system is very productive, avoids in-stand traffic and removes operators from positions of high risk. This long-term study was conducted on 12 different teams equipped with the new technology, operating in the fast-growing Acacia mangium plantations of Sarawak, Malaysia. Data were collected continuously for almost 8 months and represented 555 shifts, or over 55,000 yarding cycles - each recorded individually. This large data pool allowed for the development of robust models for system production, utilization and availability estimated respectively at: 63 m3 per productive machine hour (excluding all delays), 63 per cent and 93 per cent. The study also determined the effects of yarder type and team competence on productivity and utilization. Regression analysis of experimental data yielded a strong productivity forecast model that was highly significant, which accounted for 50 per cent of the total variability in the dataset and was validated with a non-significant error estimated at less than 1 per cent. The models reported in this study are especially robust, because they were obtained from a long-term study that covered multiple teams and accumulated an exceptionally large number of observations. While gained specifically on one yarder make (Alpine Yarder) and a specific plantation type (Acacia mangium), the information in this study can be extended to other similar machines and plantations, because the sheer volume of data allows cautious generalization. The teachings of kaizen, which suggest small-step work improvements, was adopted in order to propose the process of possible improvements, by combining elements of other harvesting systems as shown in Figure 1 below (Vorn Industries, 2017). Forestry is essentially a problem of transportation (Schenck, 1911) and the efficiency of such a transportation system will ultimately be determined by technology developments which drive system productivity (Ger & Klvac, 2014). Therefore, when we talk about systems for the future we should view them not as predictions or as prescriptions but as options that may be selected or rejected (Wood, 1979).
- Full Text:
- Date Issued: 2018
Periglacial landforms of the Ahlmannryggen and Jutulsessen areas of western Dronning Maud land, Antarctica
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
The development of natural fibre reinforced composites roof sheet
- Authors: Musikwa, Mufeba
- Date: 2018
- Subjects: Textile fibers -- Research , Textile fabrics Textile chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32927 , vital:32398
- Description: The study aims to develop natural fibre reinforced bio-epoxy composite for use as roof sheets, manufacturing and characterization to evaluate its suitability for building applications. In this study natural fibres such as flax and kenaf were selected to reinforce bio-epoxy matrix. Different weight ratios of flax and kenaf fibres were processed by needle-punching technique to produce nonwoven mats. The nonwoven mats and bio-epoxy matrix were prepared using vacuum assisted resin transfer moulding (VARTM) at room temperature until dry and cured. The effects of weathering and water aging on the static and dynamic mechanical properties of kenaf and flax composites were investigated. Flax fibre reinforced bio-epoxy composites were found to exhibit higher tensile strength at 25% fibre content of 41.5 MPa in comparison to the composites reinforced with kenaf fibres (33.0 MPa). With regards to the drop weight impact results, flax fibre reinforced bio-epoxy composites exhibited brittle failure. Water aging results showed that kenaf fibre reinforced bio-epoxy composites absorbed less water for all fibre contents in comparison to composites reinforced with flax fibres. The tensile strength and modulus of both the composites reinforced with flax and kenaf fibres were reduced after water aging. However, the composite reinforced with kenaf fibres showed the maximum reduction in tensile strength at 25% fibre content. After UV treatment both composites reinforced with flax and kenaf fibres showed a decrease in tensile strength of 6.25% and 30%, respectively. In comparison to kenaf, bioepoxy composites reinforced with flax fibres showed an increase in tensile modulus. Both composites reinforced with flax and kenaf fibres were found to be brittle and broke easily but no colour fading was observed after UV treatment. The dynamic mechanical analyses results showed that the incorporation of flax and kenaf fibres increases the storage modulus of the composites with the maximum storage modulus value exhibited by flax fibre reinforced bio-epoxy composite at 30% fibre content. The glass transition temperature of composites reinforced with both flax and kenaf fibres shifted to lower temperatures of 79 °C and 69 °C respectively, in comparison to 96 °C for bio-epoxy resin, with the incorporation of fibres.
- Full Text:
- Date Issued: 2018
- Authors: Musikwa, Mufeba
- Date: 2018
- Subjects: Textile fibers -- Research , Textile fabrics Textile chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32927 , vital:32398
- Description: The study aims to develop natural fibre reinforced bio-epoxy composite for use as roof sheets, manufacturing and characterization to evaluate its suitability for building applications. In this study natural fibres such as flax and kenaf were selected to reinforce bio-epoxy matrix. Different weight ratios of flax and kenaf fibres were processed by needle-punching technique to produce nonwoven mats. The nonwoven mats and bio-epoxy matrix were prepared using vacuum assisted resin transfer moulding (VARTM) at room temperature until dry and cured. The effects of weathering and water aging on the static and dynamic mechanical properties of kenaf and flax composites were investigated. Flax fibre reinforced bio-epoxy composites were found to exhibit higher tensile strength at 25% fibre content of 41.5 MPa in comparison to the composites reinforced with kenaf fibres (33.0 MPa). With regards to the drop weight impact results, flax fibre reinforced bio-epoxy composites exhibited brittle failure. Water aging results showed that kenaf fibre reinforced bio-epoxy composites absorbed less water for all fibre contents in comparison to composites reinforced with flax fibres. The tensile strength and modulus of both the composites reinforced with flax and kenaf fibres were reduced after water aging. However, the composite reinforced with kenaf fibres showed the maximum reduction in tensile strength at 25% fibre content. After UV treatment both composites reinforced with flax and kenaf fibres showed a decrease in tensile strength of 6.25% and 30%, respectively. In comparison to kenaf, bioepoxy composites reinforced with flax fibres showed an increase in tensile modulus. Both composites reinforced with flax and kenaf fibres were found to be brittle and broke easily but no colour fading was observed after UV treatment. The dynamic mechanical analyses results showed that the incorporation of flax and kenaf fibres increases the storage modulus of the composites with the maximum storage modulus value exhibited by flax fibre reinforced bio-epoxy composite at 30% fibre content. The glass transition temperature of composites reinforced with both flax and kenaf fibres shifted to lower temperatures of 79 °C and 69 °C respectively, in comparison to 96 °C for bio-epoxy resin, with the incorporation of fibres.
- Full Text:
- Date Issued: 2018
Influence of knowledge of the end-point on pacing during a 2000m rowing time trial
- Authors: Ferreira, Dean
- Date: 2018
- Subjects: Rowing -- Training , Rowing -- Coaching , Endurance sports -- Training , Rowers -- Ability testing , Rowing -- Training -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61636 , vital:28044
- Description: Introduction: A typical 2000 m rowing race requires maximal force production over six to eight minutes. Optimal distribution of energetic resources during such a race is vital for optimal performance. There is little research examining the pacing strategies employed by rowers, particularly at the sub-elite level. Aim: The purpose of this investigation was to determine the influence of knowledge of the end-point on pacing during a 2000 m rowing time trial. Methods: Eleven male rowers from a university rowing club volunteered to partake in the study. Each participant completed three experimental trials on an indoor rowing ergometer, each 2000 m. The only difference between the trials was the nature of the information provided beforehand. At the start of the control trial, participants were correctly informed about the distance to be covered. Participants were not informed of the distance to be completed in the unknown trial. For the deceptive trial, participants were told 1000 m would be completed, but when this distance was reached, they were told to continue for another 1000 m. During each trial muscle activity, power output, heart rate, performance time and perceptions of effort were measured.Results: The control trial was significantly (p<0.05) faster than both the unknown and deceptive trials, however the deceptive trial was the fastest of all trials at the 1000 m distance. The unknown trial was slowest at 1000 m and at 2000 m. Muscle activity, RPE, heart rate and power output were significantly (p<0.05) lower in the unknown trial compared to the control and deceptive trial. The control trial exhibited a reverse J-shape pacing profile. The deceptive trial revealed a significant (p<0.05) reduction in performance time, heart rate, power output and muscle activity after the 1000 m interval. The first 500 m interval had the fastest performance and highest power output in all trials. In all trials, RPE was highest at the end of the 2000 m, the greatest reading being obtained at the end of the control trial. During the first 1000 m of the deceptive trial, the dependant variables were similar to those in the control trial. Once the deception was revealed, there was a significant (p<0.05) reduction in the muscle activity, heart rate and power output. Conclusion: The results of this study indicate that accurate end-point information is crucial to the development of an optimal pacing strategy, and ultimately to successful performance. Rowers tend to adopt the reverse J-shape pacing profile most often due to the tactical and physiological benefits offered by this strategy. Unknown or inaccurate end-point information resulted in performance decrements due to the uncertainty associated with the exercise bout.
- Full Text:
- Date Issued: 2018
- Authors: Ferreira, Dean
- Date: 2018
- Subjects: Rowing -- Training , Rowing -- Coaching , Endurance sports -- Training , Rowers -- Ability testing , Rowing -- Training -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61636 , vital:28044
- Description: Introduction: A typical 2000 m rowing race requires maximal force production over six to eight minutes. Optimal distribution of energetic resources during such a race is vital for optimal performance. There is little research examining the pacing strategies employed by rowers, particularly at the sub-elite level. Aim: The purpose of this investigation was to determine the influence of knowledge of the end-point on pacing during a 2000 m rowing time trial. Methods: Eleven male rowers from a university rowing club volunteered to partake in the study. Each participant completed three experimental trials on an indoor rowing ergometer, each 2000 m. The only difference between the trials was the nature of the information provided beforehand. At the start of the control trial, participants were correctly informed about the distance to be covered. Participants were not informed of the distance to be completed in the unknown trial. For the deceptive trial, participants were told 1000 m would be completed, but when this distance was reached, they were told to continue for another 1000 m. During each trial muscle activity, power output, heart rate, performance time and perceptions of effort were measured.Results: The control trial was significantly (p<0.05) faster than both the unknown and deceptive trials, however the deceptive trial was the fastest of all trials at the 1000 m distance. The unknown trial was slowest at 1000 m and at 2000 m. Muscle activity, RPE, heart rate and power output were significantly (p<0.05) lower in the unknown trial compared to the control and deceptive trial. The control trial exhibited a reverse J-shape pacing profile. The deceptive trial revealed a significant (p<0.05) reduction in performance time, heart rate, power output and muscle activity after the 1000 m interval. The first 500 m interval had the fastest performance and highest power output in all trials. In all trials, RPE was highest at the end of the 2000 m, the greatest reading being obtained at the end of the control trial. During the first 1000 m of the deceptive trial, the dependant variables were similar to those in the control trial. Once the deception was revealed, there was a significant (p<0.05) reduction in the muscle activity, heart rate and power output. Conclusion: The results of this study indicate that accurate end-point information is crucial to the development of an optimal pacing strategy, and ultimately to successful performance. Rowers tend to adopt the reverse J-shape pacing profile most often due to the tactical and physiological benefits offered by this strategy. Unknown or inaccurate end-point information resulted in performance decrements due to the uncertainty associated with the exercise bout.
- Full Text:
- Date Issued: 2018
Discovery and validation of a CD4 binding aptamer through Crossover SELEX towards the preliminary development of a point-of-care aptasensor for rapid CD4+ T-cell counting
- Authors: Fellows, Tamika
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63527 , vital:28431
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Fellows, Tamika
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63527 , vital:28431
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Image processing and data analysis tools of a remote sensing-based euthrophication monitoring system
- Authors: Chamunorwa, Brighton
- Date: 2018
- Subjects: Eutrophication Image processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10210 , vital:35376
- Description: Numerous surface water bodies in South Africa face serious challenges of eutrophication despite several initiatives from government to solve the problem. Government efforts have not been successful particularly because of three issues: 1) insufficient and inconsistent water quality data and 2) the costly nature of collecting this data. Third, the limited uptake of remote sensing based technologies in water quality management due to lack of skills, as well as the lengthy and complex procedures involved in retrieving water quality parameters. This thesis aims to explore the possibilities of using satellite data and simple software for mapping and collecting water quality data. The broad goal was to determine the function of software dedicated to meet the requirements of a remote sensing-based eutrophication-monitoring system. Two specific goal were set in this study: 1. To extract software requirements from available eutrophication management documentation. This was necessary to determine the functions of the dedicated software that matches the legislative requirements and 2. To determine a design capable of handling spatial and temporal requirement of a remote sensing based eutrophication-monitoring system. The study applied Goal Based Requirement Analysis Model [GBRAM] model to extract goals from the National Eutrophication Monitoring Programme [NEMP] implementation plan document and recent publication on remote sensing of water quality monitoring conducted in South Africa. Afterwards, the study used object-oriented concepts to model suitable data objects and processes to implement spatial-temporal requirements of a remote sensing-based eutrophication-monitoring system. Based on the study findings the following are essential functions of a remote sensing based eutrophication-monitoring system. A graphical user interface that allows the user to set up a monitoring programming. Automated image processing procedures. Data assessment methods used to generate eutrophication status information. Numerous display options for viewing data in several perfectives.
- Full Text:
- Date Issued: 2018
Image processing and data analysis tools of a remote sensing-based euthrophication monitoring system
- Authors: Chamunorwa, Brighton
- Date: 2018
- Subjects: Eutrophication Image processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10210 , vital:35376
- Description: Numerous surface water bodies in South Africa face serious challenges of eutrophication despite several initiatives from government to solve the problem. Government efforts have not been successful particularly because of three issues: 1) insufficient and inconsistent water quality data and 2) the costly nature of collecting this data. Third, the limited uptake of remote sensing based technologies in water quality management due to lack of skills, as well as the lengthy and complex procedures involved in retrieving water quality parameters. This thesis aims to explore the possibilities of using satellite data and simple software for mapping and collecting water quality data. The broad goal was to determine the function of software dedicated to meet the requirements of a remote sensing-based eutrophication-monitoring system. Two specific goal were set in this study: 1. To extract software requirements from available eutrophication management documentation. This was necessary to determine the functions of the dedicated software that matches the legislative requirements and 2. To determine a design capable of handling spatial and temporal requirement of a remote sensing based eutrophication-monitoring system. The study applied Goal Based Requirement Analysis Model [GBRAM] model to extract goals from the National Eutrophication Monitoring Programme [NEMP] implementation plan document and recent publication on remote sensing of water quality monitoring conducted in South Africa. Afterwards, the study used object-oriented concepts to model suitable data objects and processes to implement spatial-temporal requirements of a remote sensing-based eutrophication-monitoring system. Based on the study findings the following are essential functions of a remote sensing based eutrophication-monitoring system. A graphical user interface that allows the user to set up a monitoring programming. Automated image processing procedures. Data assessment methods used to generate eutrophication status information. Numerous display options for viewing data in several perfectives.
- Full Text:
- Date Issued: 2018
The synthesis of functionalized carbon nanomaterial from waste tyre sourced carbon for chemosensing during purification processes
- Authors: Du Plessis, Jacolien
- Date: 2018
- Subjects: Nanostructured materials , Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/29925 , vital:30794
- Description: The short lifetime of tyres causes great environmental harm due to their non-biodegradable nature resulting in land and water pollution. Exploration of novel uses for recycled tyres is therefore imperative. The use of recycled waste tyres as carbon source for the synthesis of fluorescent chemosensing carbon nanomaterial for the detection of harmful chemicals in water is proposed in this work. Three key problems are addressed in this study: i) re-using of waste tyre products, ii) synthesis of low-cost carbon nanomaterial, iii) detection of harmful compounds within environment systems. The fluorescent triazolyl-coumarin compound, 7-(diethylamino)-3-(4-(1-hydroxyethyl)-1H-1,2,3-triazol-1-yl)-2H-chromen-2-one, was synthesized in multiple steps from 4-diethylamino salicylaldehyde. The last step included the use of Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (“click-reaction”) to form a triazole ring. Carbon spheres were synthesized through catalytic chemical vapour deposition (CVD) from waste tyre pyrolysis oil (WTPO), as the carbon source, in the presence of a catalytic amount of ferrocene. The quality and quantity of the carbon spheres had an overall improvement as the synthesis temperatures increased from 800 oC to 950 oC. The diameter of the carbon spheres reduced from 1017 nm to 577 nm as seen in TEM and SEM imaging. TGA and XRD analysis indicated a direct relationship between an increase in synthesis temperatures with an increase in the crystallinity of the carbon spheres. Commercially available naphthenic oil was used as a reference to compare the impact of the starting carbon precursor on the morphology of the carbon nanomaterial under the same reaction conditions. Multi-walled carbon nanotubes were synthesized at the lower temperatures of 800-850 oC. Carbon fibres and carbon spheres were observed at the synthesis temperatures of 900-950 oC. The carbon source played a role in the morphology of the carbon nanomaterial as it could be seen between the complex natured WTPO and the pure naphthenic oil. The purified carbon spheres synthesized at 950 oC from WTPO were functionalized with the triazolyl-coumarin units on the surface through Steglich esterification using DCC/DMAP to yield fluorescent carbon spheres. Complexation studies of the functionalized carbon spheres were done using UV/Vis spectroscopy and fluorescence with a wide range of ions; Ag+, Al3+, Co2+, Cr3+, Cu2+, Fe3+, ii Hg2+, Li+, Ni2+, Pb2+ and Zn2+. The triazolyl-coumarin carbon spheres showed reasonable sensitivity and selectivity towards Fe3+ in water with a quenching effect in fluorescence. Titration studies with Fe3+ indicating an exponential decay of quenching in the fluorescence up to 68% with detection limit at 2.73 x 10-5 M.
- Full Text:
- Date Issued: 2018
- Authors: Du Plessis, Jacolien
- Date: 2018
- Subjects: Nanostructured materials , Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/29925 , vital:30794
- Description: The short lifetime of tyres causes great environmental harm due to their non-biodegradable nature resulting in land and water pollution. Exploration of novel uses for recycled tyres is therefore imperative. The use of recycled waste tyres as carbon source for the synthesis of fluorescent chemosensing carbon nanomaterial for the detection of harmful chemicals in water is proposed in this work. Three key problems are addressed in this study: i) re-using of waste tyre products, ii) synthesis of low-cost carbon nanomaterial, iii) detection of harmful compounds within environment systems. The fluorescent triazolyl-coumarin compound, 7-(diethylamino)-3-(4-(1-hydroxyethyl)-1H-1,2,3-triazol-1-yl)-2H-chromen-2-one, was synthesized in multiple steps from 4-diethylamino salicylaldehyde. The last step included the use of Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (“click-reaction”) to form a triazole ring. Carbon spheres were synthesized through catalytic chemical vapour deposition (CVD) from waste tyre pyrolysis oil (WTPO), as the carbon source, in the presence of a catalytic amount of ferrocene. The quality and quantity of the carbon spheres had an overall improvement as the synthesis temperatures increased from 800 oC to 950 oC. The diameter of the carbon spheres reduced from 1017 nm to 577 nm as seen in TEM and SEM imaging. TGA and XRD analysis indicated a direct relationship between an increase in synthesis temperatures with an increase in the crystallinity of the carbon spheres. Commercially available naphthenic oil was used as a reference to compare the impact of the starting carbon precursor on the morphology of the carbon nanomaterial under the same reaction conditions. Multi-walled carbon nanotubes were synthesized at the lower temperatures of 800-850 oC. Carbon fibres and carbon spheres were observed at the synthesis temperatures of 900-950 oC. The carbon source played a role in the morphology of the carbon nanomaterial as it could be seen between the complex natured WTPO and the pure naphthenic oil. The purified carbon spheres synthesized at 950 oC from WTPO were functionalized with the triazolyl-coumarin units on the surface through Steglich esterification using DCC/DMAP to yield fluorescent carbon spheres. Complexation studies of the functionalized carbon spheres were done using UV/Vis spectroscopy and fluorescence with a wide range of ions; Ag+, Al3+, Co2+, Cr3+, Cu2+, Fe3+, ii Hg2+, Li+, Ni2+, Pb2+ and Zn2+. The triazolyl-coumarin carbon spheres showed reasonable sensitivity and selectivity towards Fe3+ in water with a quenching effect in fluorescence. Titration studies with Fe3+ indicating an exponential decay of quenching in the fluorescence up to 68% with detection limit at 2.73 x 10-5 M.
- Full Text:
- Date Issued: 2018
Corrosion resistance of nanocrystalline titanium zirconium nitride layers deposited on ZIRLO
- Nyembe, Hlanganani Siphelele
- Authors: Nyembe, Hlanganani Siphelele
- Date: 2018
- Subjects: Zirconium alloys , Titanium alloys Nanocrystals Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34744 , vital:33435
- Description: Zirconium (Zr) alloys are used as nuclear fuel cladding in water-cooled nuclear reactors. Being in contact with steam, the Zr-alloy is oxidised and it absorbs hydrogen. The hydrogen pickup in Zr-alloys induces embrittlement of the tubes due to hydride formation. In this study, effectiveness of corrosion resistant nanocrystalline titanium zirconium nitride (nc-TiZrN) coatings on the surface of a Zr-alloy for the reduction of corrosion and hydrogen pickup is investigated. The nc-TiZrN layers were deposited onto the surface of ZIRLO® using the cathodic arc vapour deposition (CAVD) technique. The influence of nc-TiZrN coatings on the corrosion performance of ZIRLO® was investigated under the following conditions: (a) In an oxygen atmosphere at various temperatures from 400 to 900 ℃ for 30 minutes, (b) for various exposure times from 6 – 24 hours with the temperature kept constant at 500 ℃ in a tube furnace, and (c) in pure steam for 30 days at 360 ℃ and 18.7 MPa in an autoclave. The corrosion properties of the nc-TiZrN coated ZIRLO were compared to uncoated ZIRLO for all experiments. Following corrosion testing, the TiZrN coatings and oxide layers were investigated by scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy. The TiZrN coating had a thickness of ~3.8 μm with a small number of Ti-rich and Nb-rich inclusions. The coating exhibited a single phase solid solution of Ti0.42Zr0.58N with a NaCl-type crystal structure and columnar nanocrystals. These columnar nanocrystals showed a strong {111} preferred orientation and the {111} planes of the TiZrN crystals are oriented parallel to the (001) planes of α-ZIRLO grains with <001> direction perpendicular to the coating/ZIRLO interface. The corrosion testing at various temperatures from 400 to 900 ℃ for 30 minutes showed that the TiZrN coating oxidises slowly and retained its microstructure, composition and crystallinity up to 600 ℃. At higher temperatures above 600 ℃, the TiZrN layer completely oxidised to a non-protective TiZr-oxide layer and resulted in rapid corrosion of the underlying ZIRLO substrate. The rapid corrosion was not observed in the uncoated ZIRLO sample for all temperatures. The results of samples subjected to annealing treatment at 500 ℃ in an oxygen atmosphere at various times up to 24 hours revealed that the TiZrN layer oxidises faster than ZIRLO. This was confirmed by sub-cubic and sub-parabolic oxide growth kinetics observed in the uncoated ZIRLO which are slower than the parabolic kinetics of TiZrN coated samples. In all coated samples, the spallation was observed near the edges of the samples. The spallation was caused by rapid corrosion of the underlying ZIRLO substrate which resulted from the penetration of oxygen ions between the TiZrN coating and ZIRLO substrate along the edges of the samples. In pure steam for 30 days at 360 ℃, a complete loss of the TiZrN layer occurred but the results show that the coating might have delayed the corrosion of ZIRLO. In summary, corrosion resistance of nc-TiZrN coated ZIRLO was lower than that of uncoated ZIRLO. The study shows that the failure of TiZrN coatings leads to rapid corrosion of the underlying ZIRLO substrate which was not observed on the uncoated ZIRLO. It is not yet understood why the presence TiZrN coatings reduced the oxidation resistance of ZIRLO.
- Full Text:
- Date Issued: 2018
- Authors: Nyembe, Hlanganani Siphelele
- Date: 2018
- Subjects: Zirconium alloys , Titanium alloys Nanocrystals Nanotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34744 , vital:33435
- Description: Zirconium (Zr) alloys are used as nuclear fuel cladding in water-cooled nuclear reactors. Being in contact with steam, the Zr-alloy is oxidised and it absorbs hydrogen. The hydrogen pickup in Zr-alloys induces embrittlement of the tubes due to hydride formation. In this study, effectiveness of corrosion resistant nanocrystalline titanium zirconium nitride (nc-TiZrN) coatings on the surface of a Zr-alloy for the reduction of corrosion and hydrogen pickup is investigated. The nc-TiZrN layers were deposited onto the surface of ZIRLO® using the cathodic arc vapour deposition (CAVD) technique. The influence of nc-TiZrN coatings on the corrosion performance of ZIRLO® was investigated under the following conditions: (a) In an oxygen atmosphere at various temperatures from 400 to 900 ℃ for 30 minutes, (b) for various exposure times from 6 – 24 hours with the temperature kept constant at 500 ℃ in a tube furnace, and (c) in pure steam for 30 days at 360 ℃ and 18.7 MPa in an autoclave. The corrosion properties of the nc-TiZrN coated ZIRLO were compared to uncoated ZIRLO for all experiments. Following corrosion testing, the TiZrN coatings and oxide layers were investigated by scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy. The TiZrN coating had a thickness of ~3.8 μm with a small number of Ti-rich and Nb-rich inclusions. The coating exhibited a single phase solid solution of Ti0.42Zr0.58N with a NaCl-type crystal structure and columnar nanocrystals. These columnar nanocrystals showed a strong {111} preferred orientation and the {111} planes of the TiZrN crystals are oriented parallel to the (001) planes of α-ZIRLO grains with <001> direction perpendicular to the coating/ZIRLO interface. The corrosion testing at various temperatures from 400 to 900 ℃ for 30 minutes showed that the TiZrN coating oxidises slowly and retained its microstructure, composition and crystallinity up to 600 ℃. At higher temperatures above 600 ℃, the TiZrN layer completely oxidised to a non-protective TiZr-oxide layer and resulted in rapid corrosion of the underlying ZIRLO substrate. The rapid corrosion was not observed in the uncoated ZIRLO sample for all temperatures. The results of samples subjected to annealing treatment at 500 ℃ in an oxygen atmosphere at various times up to 24 hours revealed that the TiZrN layer oxidises faster than ZIRLO. This was confirmed by sub-cubic and sub-parabolic oxide growth kinetics observed in the uncoated ZIRLO which are slower than the parabolic kinetics of TiZrN coated samples. In all coated samples, the spallation was observed near the edges of the samples. The spallation was caused by rapid corrosion of the underlying ZIRLO substrate which resulted from the penetration of oxygen ions between the TiZrN coating and ZIRLO substrate along the edges of the samples. In pure steam for 30 days at 360 ℃, a complete loss of the TiZrN layer occurred but the results show that the coating might have delayed the corrosion of ZIRLO. In summary, corrosion resistance of nc-TiZrN coated ZIRLO was lower than that of uncoated ZIRLO. The study shows that the failure of TiZrN coatings leads to rapid corrosion of the underlying ZIRLO substrate which was not observed on the uncoated ZIRLO. It is not yet understood why the presence TiZrN coatings reduced the oxidation resistance of ZIRLO.
- Full Text:
- Date Issued: 2018
Two-tissue stable isotope analysis to elucidate isotopic incorporation and trophic niche patterns for chubbyhead barb Enteromius anoplus
- Authors: Kambikambi, Manda Juliet
- Date: 2018
- Subjects: Food chains (Ecology) , Barbus -- South Africa -- Great Fish River Estuary , Stable isotopes , Freshwater fishes -- Feeding and feeds , Freshwater fishes -- Food , Fins (Anatomy) , Akaike Information Criterion , Freshwater fishes -- Conservation , Chubbyhead barb Enteromius anoplus
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61906 , vital:28082
- Description: Knowledge of trophic ecology underpins conservation and management of threatened species. Stable isotope analysis has been widely used as a more objective approach for elucidating the trophic positions of freshwater fishes. Until recently, stable isotope analysis for trophic ecology studies in freshwater fishes largely utilised white muscle tissue. This sampling approach, however, involves either euthanasia or muscle biopsy procedures that may be inappropriate for small-sized and endangered fishes. These concerns raised the need to explore and validate the utility of non-lethal alternatives such as fin clips, mucus and scales. The present study investigated the use of caudal fin tissue as a potential non-lethal alternative to muscle tissue for trophic studies on the chubbyhead barb Enteromius anoplus. The chubbyhead barb was selected as a model taxon for the present study because it is closely related or comparable in body size to a number of highly threatened small-bodied minnows in southern Africa. The chubbyhead barb was also considered an ideal species for this study because it is widespread, abundant and classified as Least Concern on the IUCN list of threatened species. The study used a two-pronged approach based on laboratory and field experiments. A laboratory experiment was conducted to quantify isotopic turnover rates and diet-tissue discrimination factors (DTDFs/A) for both muscle and fin tissues. This involved feeding chubbyhead barb two diets with distinct carbon (δ13C) and nitrogen (δ15N) values, and monitoring the temporal isotopic incorporation patterns into the two tissues. These patterns were assessed by applying least squares non-linear one- and two-compartment isotopic kinetics models. Model comparisons, based on Akaike information criterion (AIC), revealed that one- compartment models described isotopic incorporation patterns better than two-compartment models for both muscle and fin tissues. For δ13C, relatively short and comparable turnover rates were observed for muscle and fin tissues, which suggests that fin tissue could potentially provide similar inference as muscle tissue when assessing short term dietary patterns for chubbyhead barb. In contrast to δ13C, turnover rates for δ15N between muscle and fin tissue were different for both diets. Specifically, stable isotope incorporation turnover rate was faster in muscle tissue for animals that were fed on isotopically enriched diets compared to fin tissue. Conversely, stable isotope incorporation into fin tissue was faster in animals fed on isotopically depleted diets compared to muscle tissue. This suggests that knowledge of animal diet is critical when inferring fin tissue δ15N turnover rates, particularly when extrapolating both short and long term dietary patterns. Diet-tissue discrimination factors were influenced by diet type, with the fish fed on isotopically enriched diet having lower DTDFs than animals fed on isotopically depleted diets. This variation may be explained by the protein quality hypothesis, which suggests that the DTDFs of consumers will decrease as protein quality increases. When A13C and A15N values were averaged across diets in muscle and fin tissue, the values were 0.74‰ and 0.64‰, respectively, for A13C, and 5.53‰ and 5.83 ‰, respectively, for A15N. This appeared to be consistent with studies on other taxa for A13C (0-1 ‰), but for A15N (3-5 ‰) the results of this study were higher than those reported for other taxa. These results suggest that investigating appropriate DTDFs for both muscle and fin tissues is important in trophic ecology studies of these minnows. A field-based study was conducted to investigate temporal dynamics in food web patterns for chubbyhead barb in the wild within the headwaters of the Koonap River, a tributary of the Great Fish River, in the Eastern Cape, South Africa. This was achieved by collecting and comparing stable isotope data for chubbyhead barb and its potential food sources on a seasonal scale. There was a discernible difference in both the composition of carbon and nitrogen isotope values for basal food sources and macroinvertebrate communities, which suggests that this headwater stream was subject to temporal changes in food web dynamics. For chubbyhead barb, comparison of its isotopic niche sizes on a temporal scale based on both muscle and fin tissue showed differences across seasons. Furthermore, isotopic niche sizes inferred from fin tissue were larger than those inferred from muscle tissue during winter and spring, whereas during summer and autumn the isotopic niche sizes inferred from muscle and fin tissue were generally comparable. This suggests the likely influence of different metabolic and physiological processes that these two tissues undergo on a temporal scale. Therefore, difference in tissue type, and their associated metabolic pathways should be considered when using fin tissue as a substitute for muscle tissue on broad temporal scales. The results from this study indicated that caudal fin tissue has the potential to be a substitute for muscle in trophic studies of chubbyhead barb Enteromius anoplus, as well as other related small bodied endangered minnow species from South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Kambikambi, Manda Juliet
- Date: 2018
- Subjects: Food chains (Ecology) , Barbus -- South Africa -- Great Fish River Estuary , Stable isotopes , Freshwater fishes -- Feeding and feeds , Freshwater fishes -- Food , Fins (Anatomy) , Akaike Information Criterion , Freshwater fishes -- Conservation , Chubbyhead barb Enteromius anoplus
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61906 , vital:28082
- Description: Knowledge of trophic ecology underpins conservation and management of threatened species. Stable isotope analysis has been widely used as a more objective approach for elucidating the trophic positions of freshwater fishes. Until recently, stable isotope analysis for trophic ecology studies in freshwater fishes largely utilised white muscle tissue. This sampling approach, however, involves either euthanasia or muscle biopsy procedures that may be inappropriate for small-sized and endangered fishes. These concerns raised the need to explore and validate the utility of non-lethal alternatives such as fin clips, mucus and scales. The present study investigated the use of caudal fin tissue as a potential non-lethal alternative to muscle tissue for trophic studies on the chubbyhead barb Enteromius anoplus. The chubbyhead barb was selected as a model taxon for the present study because it is closely related or comparable in body size to a number of highly threatened small-bodied minnows in southern Africa. The chubbyhead barb was also considered an ideal species for this study because it is widespread, abundant and classified as Least Concern on the IUCN list of threatened species. The study used a two-pronged approach based on laboratory and field experiments. A laboratory experiment was conducted to quantify isotopic turnover rates and diet-tissue discrimination factors (DTDFs/A) for both muscle and fin tissues. This involved feeding chubbyhead barb two diets with distinct carbon (δ13C) and nitrogen (δ15N) values, and monitoring the temporal isotopic incorporation patterns into the two tissues. These patterns were assessed by applying least squares non-linear one- and two-compartment isotopic kinetics models. Model comparisons, based on Akaike information criterion (AIC), revealed that one- compartment models described isotopic incorporation patterns better than two-compartment models for both muscle and fin tissues. For δ13C, relatively short and comparable turnover rates were observed for muscle and fin tissues, which suggests that fin tissue could potentially provide similar inference as muscle tissue when assessing short term dietary patterns for chubbyhead barb. In contrast to δ13C, turnover rates for δ15N between muscle and fin tissue were different for both diets. Specifically, stable isotope incorporation turnover rate was faster in muscle tissue for animals that were fed on isotopically enriched diets compared to fin tissue. Conversely, stable isotope incorporation into fin tissue was faster in animals fed on isotopically depleted diets compared to muscle tissue. This suggests that knowledge of animal diet is critical when inferring fin tissue δ15N turnover rates, particularly when extrapolating both short and long term dietary patterns. Diet-tissue discrimination factors were influenced by diet type, with the fish fed on isotopically enriched diet having lower DTDFs than animals fed on isotopically depleted diets. This variation may be explained by the protein quality hypothesis, which suggests that the DTDFs of consumers will decrease as protein quality increases. When A13C and A15N values were averaged across diets in muscle and fin tissue, the values were 0.74‰ and 0.64‰, respectively, for A13C, and 5.53‰ and 5.83 ‰, respectively, for A15N. This appeared to be consistent with studies on other taxa for A13C (0-1 ‰), but for A15N (3-5 ‰) the results of this study were higher than those reported for other taxa. These results suggest that investigating appropriate DTDFs for both muscle and fin tissues is important in trophic ecology studies of these minnows. A field-based study was conducted to investigate temporal dynamics in food web patterns for chubbyhead barb in the wild within the headwaters of the Koonap River, a tributary of the Great Fish River, in the Eastern Cape, South Africa. This was achieved by collecting and comparing stable isotope data for chubbyhead barb and its potential food sources on a seasonal scale. There was a discernible difference in both the composition of carbon and nitrogen isotope values for basal food sources and macroinvertebrate communities, which suggests that this headwater stream was subject to temporal changes in food web dynamics. For chubbyhead barb, comparison of its isotopic niche sizes on a temporal scale based on both muscle and fin tissue showed differences across seasons. Furthermore, isotopic niche sizes inferred from fin tissue were larger than those inferred from muscle tissue during winter and spring, whereas during summer and autumn the isotopic niche sizes inferred from muscle and fin tissue were generally comparable. This suggests the likely influence of different metabolic and physiological processes that these two tissues undergo on a temporal scale. Therefore, difference in tissue type, and their associated metabolic pathways should be considered when using fin tissue as a substitute for muscle tissue on broad temporal scales. The results from this study indicated that caudal fin tissue has the potential to be a substitute for muscle in trophic studies of chubbyhead barb Enteromius anoplus, as well as other related small bodied endangered minnow species from South Africa.
- Full Text:
- Date Issued: 2018
Understanding and quantifying channel transmission loss processes in the Limpopo River Basin
- Authors: Mvandaba, Vuyelwa
- Date: 2018
- Subjects: Water-supply -- Management , Water-supply -- Limpopo River Watershed , Alluvium -- Limpopo River Watershed , Streamflow -- Limpopo River Watershed
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63797 , vital:28490
- Description: Water availability is one of the major societal issues facing the world. The ability to understand and quantify the impact of key hydrological processes on the availability of water resources is therefore integral to ensuring equitable and sustainable resource management. A review of previous hydrological studies conducted in the Limpopo River Basin has revealed a gap in the understanding of surface water-groundwater interactions, particularly channel transmission loss processes. These earlier studies, focused largely on the Limpopo River’s main stem, have attributed the existence of these streamflow losses to the presence of significant alluvial aquifers and indicated that the losses account for about 30 percent (or 1000 Mm3 a-1) of the basin’s water balance. The work conducted in this dissertation reports on the delineation of alluvial aquifers across three sub-basins of the Limpopo River Basin namely, the Mokolo (South Africa), Motloutse (Botswana) and Mzingwane (Zimbabwe) sub-basins and the estimation of potential channel transmission losses based on the alluvial aquifer properties. Additionally, an assessment of the different approaches that can be applied to simulate these channel transmission losses in the Pitman Model is presented. To delineate alluvial aquifers, general land cover classes including alluvial aquifers were produced from Landsat-8 imagery through image classification. The areal extent of the delineated alluvial aquifers was calculated using ArcMap 10.3. To quantify channel transmission losses and determine the effects on regional water resources, three approaches using the Pitman model were applied. The three approaches include an explicit transmission loss function, the use of a wetland function to represent channel-floodplain storage exchanges and the use of a ‘dummy’ reservoir to represent floodplain storage and evapotranspiration losses. Results indicate that all three approaches were able to simulate channel transmission losses, although with differing magnitudes. Observed monthly flow data were used to as a means of validating loss simulations however for each sub-basin, medium and low flows were over-simulated which accounts for water uses that were inefficiently represented due to lack of data. Knowledge of the structure of the transmission loss function dictates that it is better at representing the dynamics of channel transmission losses, as it takes into account the contribution of losses to groundwater recharge whereas the other two functions simply store water and release it back to the channel. Overall, the hydrological modelling results demonstrate the potential of each approach in reproducing the dynamics of channel transmission losses between channel and alluvial aquifer within an existing sub-basin scale hydrological model. It is believed that better quantification of losses and more efficient qualitative determination of the function which best represents transmission losses, can be attained with more reliable observed data. In conclusion, a study of this nature can be beneficial to water resource estimation programmes as it highlights the uncertainties related with quantifying channel transmission loss processes in a semi-arid environment.
- Full Text:
- Date Issued: 2018
- Authors: Mvandaba, Vuyelwa
- Date: 2018
- Subjects: Water-supply -- Management , Water-supply -- Limpopo River Watershed , Alluvium -- Limpopo River Watershed , Streamflow -- Limpopo River Watershed
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63797 , vital:28490
- Description: Water availability is one of the major societal issues facing the world. The ability to understand and quantify the impact of key hydrological processes on the availability of water resources is therefore integral to ensuring equitable and sustainable resource management. A review of previous hydrological studies conducted in the Limpopo River Basin has revealed a gap in the understanding of surface water-groundwater interactions, particularly channel transmission loss processes. These earlier studies, focused largely on the Limpopo River’s main stem, have attributed the existence of these streamflow losses to the presence of significant alluvial aquifers and indicated that the losses account for about 30 percent (or 1000 Mm3 a-1) of the basin’s water balance. The work conducted in this dissertation reports on the delineation of alluvial aquifers across three sub-basins of the Limpopo River Basin namely, the Mokolo (South Africa), Motloutse (Botswana) and Mzingwane (Zimbabwe) sub-basins and the estimation of potential channel transmission losses based on the alluvial aquifer properties. Additionally, an assessment of the different approaches that can be applied to simulate these channel transmission losses in the Pitman Model is presented. To delineate alluvial aquifers, general land cover classes including alluvial aquifers were produced from Landsat-8 imagery through image classification. The areal extent of the delineated alluvial aquifers was calculated using ArcMap 10.3. To quantify channel transmission losses and determine the effects on regional water resources, three approaches using the Pitman model were applied. The three approaches include an explicit transmission loss function, the use of a wetland function to represent channel-floodplain storage exchanges and the use of a ‘dummy’ reservoir to represent floodplain storage and evapotranspiration losses. Results indicate that all three approaches were able to simulate channel transmission losses, although with differing magnitudes. Observed monthly flow data were used to as a means of validating loss simulations however for each sub-basin, medium and low flows were over-simulated which accounts for water uses that were inefficiently represented due to lack of data. Knowledge of the structure of the transmission loss function dictates that it is better at representing the dynamics of channel transmission losses, as it takes into account the contribution of losses to groundwater recharge whereas the other two functions simply store water and release it back to the channel. Overall, the hydrological modelling results demonstrate the potential of each approach in reproducing the dynamics of channel transmission losses between channel and alluvial aquifer within an existing sub-basin scale hydrological model. It is believed that better quantification of losses and more efficient qualitative determination of the function which best represents transmission losses, can be attained with more reliable observed data. In conclusion, a study of this nature can be beneficial to water resource estimation programmes as it highlights the uncertainties related with quantifying channel transmission loss processes in a semi-arid environment.
- Full Text:
- Date Issued: 2018
The impact, on fibre quality, of changing from conventional cotton to genetically modified cotton
- Authors: van Rensburg, Joané Jansen
- Date: 2018
- Subjects: Cotton -- Genetic engineering , Cotton -- Quality Cotton
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30408 , vital:30940
- Description: This study was aimed at investigating the impact, on cotton fibre quality, of changing from conventional (non-GM) to genetically modified (GM) cotton, in both South Africa and the United States of America (USA). The cotton quality data, pre- and post-GM, generated by Cotton SA and the USDA, respectively, using the HVI systems, were accessed for 25 years in South Africa, and 27 years in the U.S. The key cotton quality parameters evaluated were staple length, micronaire and strength. These quality parameters had been measured on the Uster® HVI system by the various classing facilities in South Africa and the USA, on each bale of cotton produced within the specific country. The data for South Africa covered the period from 1992 (six years before the introduction of GM cotton) to 2016, composing at least 90% GM cotton since 2007. Data for the USA covered the period from 1990 (five years before the introduction of GM cotton) to 2016, composing at least 90% GM cotton since 2010. The data accessed and compiled, from the respective databases of two different countries, had to be electronically captured, regrouped (according to standards provided by the USDA) and thereafter analysed. It was found that the introduction and phasing in of GM cotton in both South Africa and the USA had a beneficial impact on the overall quality (FQI) of cotton produced in these countries. These positive trends in FQI were mainly caused by an increase in staple length for both countries, due to the beneficial impact that the introduction and phasing in of GM cotton had on staple length. Certain of the fibre parameters, notably micronaire, tended to fluctuate from year to year, quite unrelated to the introduction and phasing in of GM cotton, this being ascribed to fluctuating climatic conditions, and the parameter’s extreme sensitivity to such conditions. Over the period covered, cotton fibre, strength, showed a different trend for each country, remaining largely constant in South Africa, while increasing in the USA, this being unrelated to the introduction of GM cotton per sé.
- Full Text:
- Date Issued: 2018
- Authors: van Rensburg, Joané Jansen
- Date: 2018
- Subjects: Cotton -- Genetic engineering , Cotton -- Quality Cotton
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30408 , vital:30940
- Description: This study was aimed at investigating the impact, on cotton fibre quality, of changing from conventional (non-GM) to genetically modified (GM) cotton, in both South Africa and the United States of America (USA). The cotton quality data, pre- and post-GM, generated by Cotton SA and the USDA, respectively, using the HVI systems, were accessed for 25 years in South Africa, and 27 years in the U.S. The key cotton quality parameters evaluated were staple length, micronaire and strength. These quality parameters had been measured on the Uster® HVI system by the various classing facilities in South Africa and the USA, on each bale of cotton produced within the specific country. The data for South Africa covered the period from 1992 (six years before the introduction of GM cotton) to 2016, composing at least 90% GM cotton since 2007. Data for the USA covered the period from 1990 (five years before the introduction of GM cotton) to 2016, composing at least 90% GM cotton since 2010. The data accessed and compiled, from the respective databases of two different countries, had to be electronically captured, regrouped (according to standards provided by the USDA) and thereafter analysed. It was found that the introduction and phasing in of GM cotton in both South Africa and the USA had a beneficial impact on the overall quality (FQI) of cotton produced in these countries. These positive trends in FQI were mainly caused by an increase in staple length for both countries, due to the beneficial impact that the introduction and phasing in of GM cotton had on staple length. Certain of the fibre parameters, notably micronaire, tended to fluctuate from year to year, quite unrelated to the introduction and phasing in of GM cotton, this being ascribed to fluctuating climatic conditions, and the parameter’s extreme sensitivity to such conditions. Over the period covered, cotton fibre, strength, showed a different trend for each country, remaining largely constant in South Africa, while increasing in the USA, this being unrelated to the introduction of GM cotton per sé.
- Full Text:
- Date Issued: 2018
The impact of project performance on the image of the construction industry in Botswana
- Authors: Ndadi, Thabo Enert
- Date: 2018
- Subjects: Project management -- Botswana , Construction industry -- Botswana Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32826 , vital:32367
- Description: The construction industry is one of the largest sectors in the economy of Botswana, and contributes significantly to the socio-economic development of the country, averaging 6.7 per cent of the country’s gross domestic product (GDP). Botswana operates a free enterprise system where anyone is free to participate, which is supported by the existence of multi-national construction firms operating in the country. The construction industry in Botswana consists of various role players. As a developing country, Botswana’s construction industry is facing challenges of poor project implementation. The performance of the construction industry has not escaped the public‘s scrutiny of commercial construction and social development projects, resulting in negative perceptions with respect to the sector. This study focuses on the impact of project performance on the image of the construction industry in Botswana, and was conducted on projects underway. When public opinion is formed, a certain image of the business results, therefore the investigation endeavoured to establish the sources of negative perceptions towards the construction industry. To realise the aforementioned study objectives, an exploratory design sequence method was adopted henceforth applying established and tested quantitative and qualitative systems. A questionnaire was formulated and established to obtain the empirical data on randomly selected projects that were on-going or completed in the past ten years .These included public sector projects, private sector and those undertaken by parastatal organisation. The sample stratum deemed representative picture of the population, included various construction industry stakeholders. To facilitate for an effective data to inform the study, the questionnaire was categorised in three key areas of, biographic data, demographic and the industry best practice perceptions. The study determined that the capability of firms is influenced by construction management skills, and established regulatory systems. These can determine the extent to which the construction industry delivers the project within the business environment that is guided by the micro, macro and market parameters. As evidenced in the findings, the Botswana construction industry faces a skills’ gap and therefore is reliant on imported labour, and many international firms operating in the country affirm this observation. The study also addressed the existing regulatory systems, and the effectiveness of institutions. The study concludes that the existing performance regulatory systems are not adequate or they are ineffectively controlled; industry role players’ behaviour is irresponsible; there is limited skills’ capacity, and political interference accompanies project implementation. While the deterioration in the construction industry can be attributed to imported culture, it is noted that multi-national corporations (MNCs) and other foreign firms can be conduits for technology and knowledge (T&K) transfer to host countries in the developing world. Botswana with its free enterprise market and limited skill capacity and informed by the behaviour of construction industry role players, there is need for a structured integrity restoration process from both regulator and the operators. There is further need for a specific sector regulatory instrument (Act) to regulate the safety, health, and environmental operations in the construction industry. The construction industry also need to support research and development of the industry to be competitive both local and international.
- Full Text:
- Date Issued: 2018
- Authors: Ndadi, Thabo Enert
- Date: 2018
- Subjects: Project management -- Botswana , Construction industry -- Botswana Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32826 , vital:32367
- Description: The construction industry is one of the largest sectors in the economy of Botswana, and contributes significantly to the socio-economic development of the country, averaging 6.7 per cent of the country’s gross domestic product (GDP). Botswana operates a free enterprise system where anyone is free to participate, which is supported by the existence of multi-national construction firms operating in the country. The construction industry in Botswana consists of various role players. As a developing country, Botswana’s construction industry is facing challenges of poor project implementation. The performance of the construction industry has not escaped the public‘s scrutiny of commercial construction and social development projects, resulting in negative perceptions with respect to the sector. This study focuses on the impact of project performance on the image of the construction industry in Botswana, and was conducted on projects underway. When public opinion is formed, a certain image of the business results, therefore the investigation endeavoured to establish the sources of negative perceptions towards the construction industry. To realise the aforementioned study objectives, an exploratory design sequence method was adopted henceforth applying established and tested quantitative and qualitative systems. A questionnaire was formulated and established to obtain the empirical data on randomly selected projects that were on-going or completed in the past ten years .These included public sector projects, private sector and those undertaken by parastatal organisation. The sample stratum deemed representative picture of the population, included various construction industry stakeholders. To facilitate for an effective data to inform the study, the questionnaire was categorised in three key areas of, biographic data, demographic and the industry best practice perceptions. The study determined that the capability of firms is influenced by construction management skills, and established regulatory systems. These can determine the extent to which the construction industry delivers the project within the business environment that is guided by the micro, macro and market parameters. As evidenced in the findings, the Botswana construction industry faces a skills’ gap and therefore is reliant on imported labour, and many international firms operating in the country affirm this observation. The study also addressed the existing regulatory systems, and the effectiveness of institutions. The study concludes that the existing performance regulatory systems are not adequate or they are ineffectively controlled; industry role players’ behaviour is irresponsible; there is limited skills’ capacity, and political interference accompanies project implementation. While the deterioration in the construction industry can be attributed to imported culture, it is noted that multi-national corporations (MNCs) and other foreign firms can be conduits for technology and knowledge (T&K) transfer to host countries in the developing world. Botswana with its free enterprise market and limited skill capacity and informed by the behaviour of construction industry role players, there is need for a structured integrity restoration process from both regulator and the operators. There is further need for a specific sector regulatory instrument (Act) to regulate the safety, health, and environmental operations in the construction industry. The construction industry also need to support research and development of the industry to be competitive both local and international.
- Full Text:
- Date Issued: 2018
Exploration potential for copperbelt - style mineralisation in NW Province, Zambia; soil geochemistry as a targeting tool
- Authors: Mwamba, John
- Date: 2018
- Subjects: Mineralogy -- Zambia -- Copperbelt Province , River sediments -- Zambia -- Copperbelt Province , Soils -- Sampling -- Zambia -- Copperbelt Province , Prospecting -- Geophysical methods , Landsat satellites , Lufilian fold belt
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62538 , vital:28204
- Description: The NW Province of Zambia is fast becoming a major significant mining district challenging to usurp the economic importance of the traditional Copperbelt Province that has been mined for nearly a century. With latest developments at Kansanshi, Lumwana and Kalumbila mines exploration efforts in the search for Copperbelt style mineralisation have doubled up in the province in recent months. Traditional methods of stream sediment and soil sampling, geophysics, aerial photo and Landsat imagery interpretations have been employed in exploration targeting campaigns. This thesis asks the question: Can we use the Copperbelt geochemical footprint as a proxy to finding new copper deposits in NW Province? The challenge faced in such studies is that few geochemical datasets for old mines exist and the little that does is proprietary information. In some mines this dataset is entirely nonexistent - at least not in the public domain. Attempting to run orientation geochemical trials on such mines is not feasible at present due to maturity of mining and the levels of contamination of the natural environment that have occurred over several decades of mining. However, in tackling this question few Copperbelt geochemical datasets from Baluba, Nkana, Mimbula, Nchanga, Bwana Mkubwa, Mufulira West and Lufubu North were used. The findings presented in this report are that for Copperbelt style mineralisation Cu/Co, Cu/Ni, Cu/Ag ratios in soil geochemistry data should be in the ranges of 0.25 to 0.48 provided geochemical studies occurred in residual soils. These ratios hold true for sediment hosted copper-cobalt mineralisation hosted at various stratigraphic levels within the Roan Group or in upper levels elsewhere on the Central African Copperbelt. Geochemical dataset for the study areas presented in this report show that the soil geochemistry footprint in the province is not dissimilar to the soil geochemistry footprint of the traditional Copperbelt Province. This means there is great potential for finding Copperbelt style mineralisation in the province and other styles of mineralisation in which copper is associated with cobalt, lead, zinc, nickel, vanadium and molybdenum. The areas of study also possess requisite geological factors that are conducive to hosting Copperbelt style deposits. These factors include: favourable structural traps with similar trends to existing mines in the province, geophysical characteristics comparable to other deposits in the province, right geological package known to host multi-type deposits in the Katangan stratigraphic sequence, and similar geochemical footprints observed on other deposits within the Lufilian fold belt. For this reason, geochemical dataset must not be looked at in isolation but should be treated in considerations with other factors and geological environment.
- Full Text:
- Date Issued: 2018
- Authors: Mwamba, John
- Date: 2018
- Subjects: Mineralogy -- Zambia -- Copperbelt Province , River sediments -- Zambia -- Copperbelt Province , Soils -- Sampling -- Zambia -- Copperbelt Province , Prospecting -- Geophysical methods , Landsat satellites , Lufilian fold belt
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62538 , vital:28204
- Description: The NW Province of Zambia is fast becoming a major significant mining district challenging to usurp the economic importance of the traditional Copperbelt Province that has been mined for nearly a century. With latest developments at Kansanshi, Lumwana and Kalumbila mines exploration efforts in the search for Copperbelt style mineralisation have doubled up in the province in recent months. Traditional methods of stream sediment and soil sampling, geophysics, aerial photo and Landsat imagery interpretations have been employed in exploration targeting campaigns. This thesis asks the question: Can we use the Copperbelt geochemical footprint as a proxy to finding new copper deposits in NW Province? The challenge faced in such studies is that few geochemical datasets for old mines exist and the little that does is proprietary information. In some mines this dataset is entirely nonexistent - at least not in the public domain. Attempting to run orientation geochemical trials on such mines is not feasible at present due to maturity of mining and the levels of contamination of the natural environment that have occurred over several decades of mining. However, in tackling this question few Copperbelt geochemical datasets from Baluba, Nkana, Mimbula, Nchanga, Bwana Mkubwa, Mufulira West and Lufubu North were used. The findings presented in this report are that for Copperbelt style mineralisation Cu/Co, Cu/Ni, Cu/Ag ratios in soil geochemistry data should be in the ranges of 0.25 to 0.48 provided geochemical studies occurred in residual soils. These ratios hold true for sediment hosted copper-cobalt mineralisation hosted at various stratigraphic levels within the Roan Group or in upper levels elsewhere on the Central African Copperbelt. Geochemical dataset for the study areas presented in this report show that the soil geochemistry footprint in the province is not dissimilar to the soil geochemistry footprint of the traditional Copperbelt Province. This means there is great potential for finding Copperbelt style mineralisation in the province and other styles of mineralisation in which copper is associated with cobalt, lead, zinc, nickel, vanadium and molybdenum. The areas of study also possess requisite geological factors that are conducive to hosting Copperbelt style deposits. These factors include: favourable structural traps with similar trends to existing mines in the province, geophysical characteristics comparable to other deposits in the province, right geological package known to host multi-type deposits in the Katangan stratigraphic sequence, and similar geochemical footprints observed on other deposits within the Lufilian fold belt. For this reason, geochemical dataset must not be looked at in isolation but should be treated in considerations with other factors and geological environment.
- Full Text:
- Date Issued: 2018
A baseline survey of channel geomorphology with particular reference to the effects of sediment characteristics on ecosystem health in the Tsitsa River, Eastern Cape, South Africa
- Huchzermeyer, Nicholaus Heinrich
- Authors: Huchzermeyer, Nicholaus Heinrich
- Date: 2018
- Subjects: Fluvial geomorphology -- South Africa -- Eastern Cape , Stream health -- South Africa -- Eastern Cape , River sediments -- South Africa -- Eastern Cape , Watershed management -- South Africa -- Eastern Cape , Dams -- Environmental aspects -- South Africa -- Eastern Cape , Tsitsa River (South Africa) , Ntabelanga Dam (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58056 , vital:27040
- Description: Fluvial systems are dynamic systems in which variables in a catchment and river channel affect the morphology of river reaches. South African rivers are increasingly being exposed to stresses from a combination of factors, one of the most prevalent being the impacts of damming rivers which result in varying downstream sediment fluxes and flow regimes. The sediment load combined with flow characteristics for respective river channels provides the physical habitat for aquatic ecosystems. The damming of the Tsitsa River, through the construction of the Ntabelanga Dam, will change the overall downstream geomorphology. This creates an opportunity for research in the preconstruction window. The current condition of the Tsitsa River was monitored by completing a baseline survey of the channel geomorphology with specific reference to the influence of sediment on river habitats and ecosystem health. Five sites were established in variable reaches of the Tsitsa River, with Site 1 located above the proposed Ntabelanga Dam inundation and Sites 2-5 below the proposed dam wall. Each site included a range of features that can be monitored for their response to the dam. Physical variables, water quality and biota were monitored seasonally to note changes in habitat quality. A baseline survey of the present geomorphology and associated instream habitats of the selected reaches was set up by conducting cross-sectional surveys of channel topography, water slope surveys, discharge measurements and visual and quantitative assessments of substrate. Level loggers were installed at each site to collect continuous data on variations in depth and temperature. Monitoring surveys, in terms of fine sediment accumulation, were conducted to characterise dynamic habitat arrangements and macroinvertebrate community composition. A taxa related physical habitat score for the Tsitsa River was created. The relationship between water quality, physical and ecological characteristics of the Tsitsa River will aid further research in the area as well as create a better understanding of the influence of sediment on river habitats and ecosystem health. Monitoring sites can be used to monitor the impact of catchment-wide rehabilitation on river health prior to the dam being built. After dam construction, the top site above the dam inundation can still be used as a point to monitor the impact of catchment rehabilitation on ecosystem health in terms of fine sediment accumulation.
- Full Text:
- Date Issued: 2018
- Authors: Huchzermeyer, Nicholaus Heinrich
- Date: 2018
- Subjects: Fluvial geomorphology -- South Africa -- Eastern Cape , Stream health -- South Africa -- Eastern Cape , River sediments -- South Africa -- Eastern Cape , Watershed management -- South Africa -- Eastern Cape , Dams -- Environmental aspects -- South Africa -- Eastern Cape , Tsitsa River (South Africa) , Ntabelanga Dam (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58056 , vital:27040
- Description: Fluvial systems are dynamic systems in which variables in a catchment and river channel affect the morphology of river reaches. South African rivers are increasingly being exposed to stresses from a combination of factors, one of the most prevalent being the impacts of damming rivers which result in varying downstream sediment fluxes and flow regimes. The sediment load combined with flow characteristics for respective river channels provides the physical habitat for aquatic ecosystems. The damming of the Tsitsa River, through the construction of the Ntabelanga Dam, will change the overall downstream geomorphology. This creates an opportunity for research in the preconstruction window. The current condition of the Tsitsa River was monitored by completing a baseline survey of the channel geomorphology with specific reference to the influence of sediment on river habitats and ecosystem health. Five sites were established in variable reaches of the Tsitsa River, with Site 1 located above the proposed Ntabelanga Dam inundation and Sites 2-5 below the proposed dam wall. Each site included a range of features that can be monitored for their response to the dam. Physical variables, water quality and biota were monitored seasonally to note changes in habitat quality. A baseline survey of the present geomorphology and associated instream habitats of the selected reaches was set up by conducting cross-sectional surveys of channel topography, water slope surveys, discharge measurements and visual and quantitative assessments of substrate. Level loggers were installed at each site to collect continuous data on variations in depth and temperature. Monitoring surveys, in terms of fine sediment accumulation, were conducted to characterise dynamic habitat arrangements and macroinvertebrate community composition. A taxa related physical habitat score for the Tsitsa River was created. The relationship between water quality, physical and ecological characteristics of the Tsitsa River will aid further research in the area as well as create a better understanding of the influence of sediment on river habitats and ecosystem health. Monitoring sites can be used to monitor the impact of catchment-wide rehabilitation on river health prior to the dam being built. After dam construction, the top site above the dam inundation can still be used as a point to monitor the impact of catchment rehabilitation on ecosystem health in terms of fine sediment accumulation.
- Full Text:
- Date Issued: 2018
Synthesis, characterization and in vitro antiplasmodial evaluation of 4-& 8-aminoquinoline based-hybrid compounds
- Authors: Nqoro, Xhamla
- Date: 2018
- Subjects: Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14649 , vital:40026
- Description: Malaria is a deadly disease and its drug resistance has been reported to be a challenge globally. The death toll caused by malaria has increased rapidly in different regions of the world. Quinoline scaffold molecules are combined with other classes of antimalarials to tackle drug resistance. The combination of quinoline scaffolds with other antimalarial compounds and metals-based drugs have been reported to be a potential approach to overcome drug resistance common in the currently used antimalarials. 4-Aminoquinoline was hybridized with selected organic molecules and metal-based compounds to form a class of hybrid compounds containing either an amide bond or ester bond as a linker between the parent molecules. 4-Aminoquinoline derivatives are known compounds and they were prepared via known synthetic routes and characterized. The hybrid compounds were characterized and the FTIR results confirmed the successful linkage of 4-aminoquinoline derivatives to selected organic scaffolds to form hybrid compounds. NMR results confirmed the successful formation of hybrid compounds. MS showed signals of the hybrid molecules confirming the successful isolation of the hybrid compounds. In vitro antiplasmodial assay was performed against asexual parasite and chloroquine was used as a reference drug. The percentage inhibition effects of the hybrid compounds were in a range of 96-102% at 5 µM and 36-96% at 1 µM suggesting that the percentage inhibition effect of the hybrid compounds was influenced by the drug concentration. Hybridization of either 4-aminosalicylic scaffold or ferrocene butanoic acid with 4- aminoquinoline derivatives is a potential synthetic route that can result in potent antimalarials. However, more research is needed to fully understand the structure-activity relationship of these hybrid compounds.
- Full Text:
- Date Issued: 2018
- Authors: Nqoro, Xhamla
- Date: 2018
- Subjects: Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14649 , vital:40026
- Description: Malaria is a deadly disease and its drug resistance has been reported to be a challenge globally. The death toll caused by malaria has increased rapidly in different regions of the world. Quinoline scaffold molecules are combined with other classes of antimalarials to tackle drug resistance. The combination of quinoline scaffolds with other antimalarial compounds and metals-based drugs have been reported to be a potential approach to overcome drug resistance common in the currently used antimalarials. 4-Aminoquinoline was hybridized with selected organic molecules and metal-based compounds to form a class of hybrid compounds containing either an amide bond or ester bond as a linker between the parent molecules. 4-Aminoquinoline derivatives are known compounds and they were prepared via known synthetic routes and characterized. The hybrid compounds were characterized and the FTIR results confirmed the successful linkage of 4-aminoquinoline derivatives to selected organic scaffolds to form hybrid compounds. NMR results confirmed the successful formation of hybrid compounds. MS showed signals of the hybrid molecules confirming the successful isolation of the hybrid compounds. In vitro antiplasmodial assay was performed against asexual parasite and chloroquine was used as a reference drug. The percentage inhibition effects of the hybrid compounds were in a range of 96-102% at 5 µM and 36-96% at 1 µM suggesting that the percentage inhibition effect of the hybrid compounds was influenced by the drug concentration. Hybridization of either 4-aminosalicylic scaffold or ferrocene butanoic acid with 4- aminoquinoline derivatives is a potential synthetic route that can result in potent antimalarials. However, more research is needed to fully understand the structure-activity relationship of these hybrid compounds.
- Full Text:
- Date Issued: 2018
Understanding the extension capacity needs of the CapeNature Stewardship Programme in the Western Cape Province of South Africa
- Coetzee, Johannes Christiaan
- Authors: Coetzee, Johannes Christiaan
- Date: 2018
- Subjects: Conservation projects (Natural resources) , Psychometrics , Adaptive natural resource management , Biodiversity conservation , CapeNature Stewardship Programme
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63220 , vital:28383
- Description: There is an increasing call for conservation programmes to provide sound evidence of effectiveness, and employing empirical evaluations can assist in the transition to evidence-based conservation practices. The objectives of this research were to develop a logic model for the CapeNature Stewardship Programme which would articulate the programme's theory of operation with respect to its Stewardship Programme landholders. The second major objective was to develop psychometric instruments for assessing the motivations and satisfactions of the programme's stewardship landholders. Both objectives included the aim to provide robust and repeatable instruments for exploring landholder's psychology, and developing a programme's theory of operation to understand the programme and improve with understanding the needs of the landowners. In this regard the processes and methodologies employed represent a major component of this research. A mixed methods approach was utilized, including stakeholder and volunteer surveys, conducted via mailing hardcopies and the internet, together with three focus groups held with the programme's management, extension staff and the stewardship landholders. Analysis of the data thus collected included both qualitative and quantitative approaches, specifically coding and content analysis, together with statistical tests of internal consistency, factor analysis and doubling correspondence analysis. Robust indices for example validity and internal consistency were developed for assessing landholder’s satisfaction with extension and level of satisfaction with the stewardship programme (Babbie 2007). These indices revealed that landholders in the Stewardship Programme are not satisfied with the programme, and exhibit behaviours suggesting they act as advocates for the programme. Demographic data and additional information provided further insights into the programme. The development of a method for articulating the programme's theory of operation is represented, together with four logic models which graphically illustrate this theory. This process and theory allowed for recommendations to be provided for the programme's improvement. A platform for adaptive management and further evaluations of this, and similar programmes, represents a major outcome of this research, understanding the extension capacity needs for the conservation of biodiversity in the CapeNature Stewardship Programme to function as a model for improving the implementation of the programme across the Western Cape, South Africa. This research feeds into an evaluation of CapeNature’s Biodiveristy Stewardship programme and demonstrates the importance of incorporating psychology into conservation interventions.
- Full Text:
- Date Issued: 2018
- Authors: Coetzee, Johannes Christiaan
- Date: 2018
- Subjects: Conservation projects (Natural resources) , Psychometrics , Adaptive natural resource management , Biodiversity conservation , CapeNature Stewardship Programme
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63220 , vital:28383
- Description: There is an increasing call for conservation programmes to provide sound evidence of effectiveness, and employing empirical evaluations can assist in the transition to evidence-based conservation practices. The objectives of this research were to develop a logic model for the CapeNature Stewardship Programme which would articulate the programme's theory of operation with respect to its Stewardship Programme landholders. The second major objective was to develop psychometric instruments for assessing the motivations and satisfactions of the programme's stewardship landholders. Both objectives included the aim to provide robust and repeatable instruments for exploring landholder's psychology, and developing a programme's theory of operation to understand the programme and improve with understanding the needs of the landowners. In this regard the processes and methodologies employed represent a major component of this research. A mixed methods approach was utilized, including stakeholder and volunteer surveys, conducted via mailing hardcopies and the internet, together with three focus groups held with the programme's management, extension staff and the stewardship landholders. Analysis of the data thus collected included both qualitative and quantitative approaches, specifically coding and content analysis, together with statistical tests of internal consistency, factor analysis and doubling correspondence analysis. Robust indices for example validity and internal consistency were developed for assessing landholder’s satisfaction with extension and level of satisfaction with the stewardship programme (Babbie 2007). These indices revealed that landholders in the Stewardship Programme are not satisfied with the programme, and exhibit behaviours suggesting they act as advocates for the programme. Demographic data and additional information provided further insights into the programme. The development of a method for articulating the programme's theory of operation is represented, together with four logic models which graphically illustrate this theory. This process and theory allowed for recommendations to be provided for the programme's improvement. A platform for adaptive management and further evaluations of this, and similar programmes, represents a major outcome of this research, understanding the extension capacity needs for the conservation of biodiversity in the CapeNature Stewardship Programme to function as a model for improving the implementation of the programme across the Western Cape, South Africa. This research feeds into an evaluation of CapeNature’s Biodiveristy Stewardship programme and demonstrates the importance of incorporating psychology into conservation interventions.
- Full Text:
- Date Issued: 2018
Classification of Distinct Fuzzy Subgroups of the Dihedral Group Dp nq for p and q distinct primes and n ∈ N
- Authors: Nxala, Baphumelele Ellen
- Date: 2018
- Subjects: Fuzzy mathematics Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14516 , vital:39997
- Description: In this dissertation, we classify distinct fuzzy subgroups of the dihedral group Dpnq, for p and q distinct primes and n ∈ N, under a natural equivalence relation of fuzzy subgroups and a fuzzy isomorphism. We aim to present formulae for the number of maximal chains and the number of distinct fuzzy subgroups of this group. Our study will include some theory on non-abelian groups since the classification of distinct fuzzy subgroups of this group relies on the crisp characterization of maximal chains. We give the definition of a natural equivalence relation introduced by Murali and Makamba in [67] which we will use in this study. Based on this definition, we introduce two counting techniques that we will use to compute the number of distinct fuzzy subgroups of Dpnq. In this dissertation, we use the criss-cut counting technique as our primary method of enumeration, and the cross-cut method serves as a means of verifying results we obtain from our primary method. To classify distinct fuzzy subgroups of this group, we begin by investigating the dihedral groups Dpnq, for p and q distinct primes and specific values of n = 2 and 3 to observe a trend. We classify the flags of these groups using the characterization of flags introduced in [93]. From this characterization, we then present formulae for the number of distinct fuzzy subgroups attributed to the flags of Dp 2q and Dp 3q . To generalise results for Dpnq, for p and q distinct primes and n ∈ N, we characterize the flags of this group and classify them as either cyclic, mdcyclic for 1 ≤ m ≤ n, or b-cyclic. Finally, we establish a general formula for the number of distinct fuzzy subgroups obtainable from these flags. We conclude by comparing results obtained from using our general formula to those obtained by other researchers for the same group. Based on the results from this study, we give an outline of future research work
- Full Text:
- Date Issued: 2018
- Authors: Nxala, Baphumelele Ellen
- Date: 2018
- Subjects: Fuzzy mathematics Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14516 , vital:39997
- Description: In this dissertation, we classify distinct fuzzy subgroups of the dihedral group Dpnq, for p and q distinct primes and n ∈ N, under a natural equivalence relation of fuzzy subgroups and a fuzzy isomorphism. We aim to present formulae for the number of maximal chains and the number of distinct fuzzy subgroups of this group. Our study will include some theory on non-abelian groups since the classification of distinct fuzzy subgroups of this group relies on the crisp characterization of maximal chains. We give the definition of a natural equivalence relation introduced by Murali and Makamba in [67] which we will use in this study. Based on this definition, we introduce two counting techniques that we will use to compute the number of distinct fuzzy subgroups of Dpnq. In this dissertation, we use the criss-cut counting technique as our primary method of enumeration, and the cross-cut method serves as a means of verifying results we obtain from our primary method. To classify distinct fuzzy subgroups of this group, we begin by investigating the dihedral groups Dpnq, for p and q distinct primes and specific values of n = 2 and 3 to observe a trend. We classify the flags of these groups using the characterization of flags introduced in [93]. From this characterization, we then present formulae for the number of distinct fuzzy subgroups attributed to the flags of Dp 2q and Dp 3q . To generalise results for Dpnq, for p and q distinct primes and n ∈ N, we characterize the flags of this group and classify them as either cyclic, mdcyclic for 1 ≤ m ≤ n, or b-cyclic. Finally, we establish a general formula for the number of distinct fuzzy subgroups obtainable from these flags. We conclude by comparing results obtained from using our general formula to those obtained by other researchers for the same group. Based on the results from this study, we give an outline of future research work
- Full Text:
- Date Issued: 2018