An investigation of the aquatic macroinvertebrate fauna of the southern Great Escarpment (South Africa): insights from ecological and genetic studies
- Authors: Taylor, Chantal Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4275 , http://hdl.handle.net/10962/d1020839
- Description: Biological diversity in freshwater biomes is vital to maintain healthy, functioning ecosystems with resilience to disturbance and the impacts of climate change. Freshwater ecosystems provide essential resources to life on Earth. However, as increasing pressure is being placed on the environment by human population growth, the quality of freshwater resources and the health of these ecosystems are at risk. Mountain streams provide an important source of water and are usually less affected by anthropogenic stressors, compared to lowland freshwaters. These montane streams are therefore of important conservation value and due to their untransformed nature serve as ideal ecosystems for biodiversity studies and as reference sites for studies on environmental change. This study explores aquatic macroinvertebrate biodiversity of the southern Great Escarpment in South Africa. Species assemblages and the environmental variables of each site were sampled from first order streams across five different mountain blocks along the Great Escarpment. Additionally, mitochondrial DNA of three mayfly species (Afroptilum sudafricanum, Demoreptus natalensis and Demoreptus capensis), commonly occurring in the study area, was analysed to compare the genetic diversity between habitat specialist and habitat generalist species. A total of 2 595 macroinvertebrate specimens from 47 families and 86 species were collected with several interesting and potentially new species being discovered. Partitioned diversity analyses indicate that macroinvertebrate diversity varies across mountain blocks. Multivariate analyses indicate that differences in assemblages could be attributed to differences in environmental variables between sites, particularly water velocity, total dissolved solids and salinity. As these environmental variables reflect of the topography of the sites, differences in species assemblages was attributed to difference in topography and therefore biotopes present. Habitat-restricted mayfly species (D. natalensis and D. capensis), occur in distinct populations confined to mountains blocks. Isolation-by-distance analyses further emphasis that these species are genetically restricted by their habitat preference for mountain streams. In contrast, A. sudafricanum, a habitat generalist, showed no indication of genetic structure due to location or distance. Possible cryptic taxa and new species were identified within A. sudafricanum and Dermoreptus respectively. This study provides an important contribution to the baseline data of freshwater macroinvertebrate diversity for the southern Great Escarpment region and provides insights into the considerable genetic diversity of selected aquatic taxa across this region.
- Full Text:
- Date Issued: 2016
- Authors: Taylor, Chantal Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4275 , http://hdl.handle.net/10962/d1020839
- Description: Biological diversity in freshwater biomes is vital to maintain healthy, functioning ecosystems with resilience to disturbance and the impacts of climate change. Freshwater ecosystems provide essential resources to life on Earth. However, as increasing pressure is being placed on the environment by human population growth, the quality of freshwater resources and the health of these ecosystems are at risk. Mountain streams provide an important source of water and are usually less affected by anthropogenic stressors, compared to lowland freshwaters. These montane streams are therefore of important conservation value and due to their untransformed nature serve as ideal ecosystems for biodiversity studies and as reference sites for studies on environmental change. This study explores aquatic macroinvertebrate biodiversity of the southern Great Escarpment in South Africa. Species assemblages and the environmental variables of each site were sampled from first order streams across five different mountain blocks along the Great Escarpment. Additionally, mitochondrial DNA of three mayfly species (Afroptilum sudafricanum, Demoreptus natalensis and Demoreptus capensis), commonly occurring in the study area, was analysed to compare the genetic diversity between habitat specialist and habitat generalist species. A total of 2 595 macroinvertebrate specimens from 47 families and 86 species were collected with several interesting and potentially new species being discovered. Partitioned diversity analyses indicate that macroinvertebrate diversity varies across mountain blocks. Multivariate analyses indicate that differences in assemblages could be attributed to differences in environmental variables between sites, particularly water velocity, total dissolved solids and salinity. As these environmental variables reflect of the topography of the sites, differences in species assemblages was attributed to difference in topography and therefore biotopes present. Habitat-restricted mayfly species (D. natalensis and D. capensis), occur in distinct populations confined to mountains blocks. Isolation-by-distance analyses further emphasis that these species are genetically restricted by their habitat preference for mountain streams. In contrast, A. sudafricanum, a habitat generalist, showed no indication of genetic structure due to location or distance. Possible cryptic taxa and new species were identified within A. sudafricanum and Dermoreptus respectively. This study provides an important contribution to the baseline data of freshwater macroinvertebrate diversity for the southern Great Escarpment region and provides insights into the considerable genetic diversity of selected aquatic taxa across this region.
- Full Text:
- Date Issued: 2016
An investigation on the effect of Russian wheat aphid (Diuraphis noxia Kurdjumov) population growth and feeding damage on selected barley (Hordeum vulgare L.) cultivars under ambient and elevated CO2
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
Assessing estuarine nursery habitats for Cape Stumpnose (Rhabdosargus holubi), (Pisces: Sparidae) in a warm-temperate estuary in the Eastern Cape, South Africa
- Authors: Leslie, Timothy David
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3178 , vital:20381
- Description: The nursery role hypothesis provides an approach for assessing the nursery function of habitat types within estuaries. This study attempted to assess the nursery value of the dominant estuarine habitats in the Bushmans Estuary for Rhabdosargus holubi (Steindachner 1881) by analysing habitat complexity, relative abundance and behaviour of R. holubi and using stomach contents analysis and dietary diatom composition as indicative of feeding habitat. Structural habitat complexity was assessed in Zostera capensis (Setchell) seagrass and Spartina maritima (Curtis Fernald) salt marsh by sampling above-ground stem density and length, and total cover per unit area (Ct/At). Dimensionless habitat complexity indices such as the interstitial spatial index (ISI) at three magnifications and fractal geometry at two magnifications were used to further analyse habitat complexity. Above-ground biomass (P<0.05) in each season and canopy height (P<0.001) were significantly higher in salt marsh than in seagrass whilst stem density was significantly higher in seagrass than in salt marsh in each season (P<0.001). Each dimensionless index indicated that complexity is notably higher in seagrass than in the salt marsh. Using dimensionless indices that analyse complexity at different spatial scales provided a better analysis of habitat complexity than canopy height and biomass as it allowed for direct comparisons between habitat types. Underwater video cameras were deployed in seagrass, salt marsh and sand flat habitats to assess the relative abundance and behaviour of R. holubi. The relative abundance of R. holubi was significantly higher in seagrass than salt marsh and sand flats, whilst the behaviour of R. holubi indicated a high degree of habitat use in structured habitats and a low degree of habitat use in unstructured sand flat habitats. This indicated that not only are juvenile R. holubi a vegetation-associated species, but also a species that prefers seagrass to salt marsh.
- Full Text:
- Date Issued: 2016
- Authors: Leslie, Timothy David
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3178 , vital:20381
- Description: The nursery role hypothesis provides an approach for assessing the nursery function of habitat types within estuaries. This study attempted to assess the nursery value of the dominant estuarine habitats in the Bushmans Estuary for Rhabdosargus holubi (Steindachner 1881) by analysing habitat complexity, relative abundance and behaviour of R. holubi and using stomach contents analysis and dietary diatom composition as indicative of feeding habitat. Structural habitat complexity was assessed in Zostera capensis (Setchell) seagrass and Spartina maritima (Curtis Fernald) salt marsh by sampling above-ground stem density and length, and total cover per unit area (Ct/At). Dimensionless habitat complexity indices such as the interstitial spatial index (ISI) at three magnifications and fractal geometry at two magnifications were used to further analyse habitat complexity. Above-ground biomass (P<0.05) in each season and canopy height (P<0.001) were significantly higher in salt marsh than in seagrass whilst stem density was significantly higher in seagrass than in salt marsh in each season (P<0.001). Each dimensionless index indicated that complexity is notably higher in seagrass than in the salt marsh. Using dimensionless indices that analyse complexity at different spatial scales provided a better analysis of habitat complexity than canopy height and biomass as it allowed for direct comparisons between habitat types. Underwater video cameras were deployed in seagrass, salt marsh and sand flat habitats to assess the relative abundance and behaviour of R. holubi. The relative abundance of R. holubi was significantly higher in seagrass than salt marsh and sand flats, whilst the behaviour of R. holubi indicated a high degree of habitat use in structured habitats and a low degree of habitat use in unstructured sand flat habitats. This indicated that not only are juvenile R. holubi a vegetation-associated species, but also a species that prefers seagrass to salt marsh.
- Full Text:
- Date Issued: 2016
Assessing the vulnerability of resource-poor households to disasters associated with climate variability using remote sensing and GIS techniques in the Nkonkobe Local Municipality, Eastern Cape Province, South Africa
- Authors: Chari, Martin Munashe
- Date: 2016
- Subjects: Climatic changes -- Forecasting Natural resources -- Remote sensing Droughts -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2425 , vital:27837
- Description: The main objective of the study was to assess the extent to which resource-poor households in selected villages of Nkonkobe Local Municipality in the Eastern Cape Province of South Africa are vulnerable to drought by using an improvised remote sensing and Geographic Information System (GIS)-based mapping approach. The research methodology was comprised of 1) assessment of vulnerability levels and 2) the calculation of established drought assessment indices comprising the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI) from wet-season Landsat images covering a period of 29 years from 1985 to 2014 in order to objectively determine the temporal recurrence of drought in Nkonkobe Local Municipality. Vulnerability of households to drought was determined by using a multi-step GIS-based mapping approach in which 3 components comprising exposure, sensitivity and adaptive capacity were simultaneously analysed and averaged to determine the magnitude of vulnerability. Thereafter, the Analytical Hierarchy Process (AHP) was used to establish weighted contributions of these components to vulnerability. The weights applied to the AHP were obtained from the 2012 - 2017 Nkonkobe Integrated Development Plan (IDP) and perceptions that were solicited from key informants who were judged to be knowledgeable about the subject. A Kruskal-Wallis H test on demographic data for water access revealed that the demographic results are independent of choice of data acquired from different data providers (χ2(2) = 1.26, p = 0.533, with a mean ranked population scores of 7.4 for ECSECC, 6.8 for Quantec and 9.8 for StatsSA). Simple linear regression analysis revealed strong positive correlations between NDWI and NDVI ((r = 0.99609375, R2 = 1, for 1985), 1995 (r = 0.99609375, R2 = 1 for 1995), (r = 0.99609375, R2 = 1 for 2005) and (r = 0.99609375, R2 = 1 for 2014). The regression analysis proved that vegetation condition depends on surface water arising from rainfall. The results indicate that the whole of Nkonkobe Local Municipality is susceptible to drought with villages in south eastern part being most vulnerable to droughts due to high sensitivity and low adaptive capacity.
- Full Text:
- Date Issued: 2016
- Authors: Chari, Martin Munashe
- Date: 2016
- Subjects: Climatic changes -- Forecasting Natural resources -- Remote sensing Droughts -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2425 , vital:27837
- Description: The main objective of the study was to assess the extent to which resource-poor households in selected villages of Nkonkobe Local Municipality in the Eastern Cape Province of South Africa are vulnerable to drought by using an improvised remote sensing and Geographic Information System (GIS)-based mapping approach. The research methodology was comprised of 1) assessment of vulnerability levels and 2) the calculation of established drought assessment indices comprising the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI) from wet-season Landsat images covering a period of 29 years from 1985 to 2014 in order to objectively determine the temporal recurrence of drought in Nkonkobe Local Municipality. Vulnerability of households to drought was determined by using a multi-step GIS-based mapping approach in which 3 components comprising exposure, sensitivity and adaptive capacity were simultaneously analysed and averaged to determine the magnitude of vulnerability. Thereafter, the Analytical Hierarchy Process (AHP) was used to establish weighted contributions of these components to vulnerability. The weights applied to the AHP were obtained from the 2012 - 2017 Nkonkobe Integrated Development Plan (IDP) and perceptions that were solicited from key informants who were judged to be knowledgeable about the subject. A Kruskal-Wallis H test on demographic data for water access revealed that the demographic results are independent of choice of data acquired from different data providers (χ2(2) = 1.26, p = 0.533, with a mean ranked population scores of 7.4 for ECSECC, 6.8 for Quantec and 9.8 for StatsSA). Simple linear regression analysis revealed strong positive correlations between NDWI and NDVI ((r = 0.99609375, R2 = 1, for 1985), 1995 (r = 0.99609375, R2 = 1 for 1995), (r = 0.99609375, R2 = 1 for 2005) and (r = 0.99609375, R2 = 1 for 2014). The regression analysis proved that vegetation condition depends on surface water arising from rainfall. The results indicate that the whole of Nkonkobe Local Municipality is susceptible to drought with villages in south eastern part being most vulnerable to droughts due to high sensitivity and low adaptive capacity.
- Full Text:
- Date Issued: 2016
Assessment of rangeland condition and evaluation of farmers' perception in Njwaxa and Mbizana communal rangelands of the Eastern Cape, South Africa
- Authors: Ngcofe, Odwa Armstrong
- Date: 2016
- Subjects: Rangelands -- South Africa -- Eastern Cape Land tenure -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13259 , vital:39627
- Description: This study was conducted to determine of rangeland condition in terms of botanical composition, soil nutrient composition, and also to evaluate farmers’ perception on rangeland condition and degradation in two communal villages Njwaxa and Mbizana in the Eastern Cape Province of South Africa in 2014. A Structured questionnaire consisting of close and open-ended questions was used to investigate farmers’ perceptions on range condition, land degradation, and their causes. Fifty households with livestock were randomly selected in two communal areas of Middledrift (i.e. Njwaxa and Mbizana). Respondents of 21 years and above were selected. For assessment of range condition three homogeneous vegetation units (HVU) were demarcated in all study sites, namely slope; valley and toplands were demarcated and sub-divided into four 100m x 50m replicates. In each replicate, four 100m transects were laid parallel to each other 25m apart 1m2 quadrant was systematically located four times along each transect for herbaceous vegetation and soil sampling. The step point method was employed to determine herbaceous species composition and basal cover. A 400m2 belt transect was used to determine woody vegetation composition, density and tree equivalents in each HVU. The germination method was employed for soil seed bank composition and plant density. The soil micro and macro nutrients (N, P, K OC, Ca, Mg, Zn, Cu and Mn) and pH were also analyzed The majority of the respondents were between the ages of 51-60 years. Most of the farmers had more cattle (38percent) than goats (32percent) and sheep (30percent). Livestock numbers were perceived to have declined over the previous 20 years by the majority of respondents (96percent). The respondents indicated that their rangelands were mainly used for browsing (1.37), fire wood (2.01), building and fencing (2.63) and medical purposes (3.66). All the respondents indicated that their rangelands were highly degraded. Sheet erosion (50percent) was perceived to be the major type of soil erosion indicator mentioned by the farmers, followed by gully erosion (29percent) and rill erosion (21percent). The rangeland was dominated by Increaser II (pioneer) (63.2 percent) grass species followed by Decreaser (mesophytes) species (26.3percent). Digitaria eriantha in the valley (53.5 percent) was significantly higher (p<0.05) than both in the top (10.5percent) and sloppy areas (33.5percent) at Njwaxa communal rangeland, the abundance of D. eriantha was significantly higher (p<0.05) than top and valley in Mbizana communal rangeland. The results showed that soil seed banks were dominated by perennials, followed by annuals and biennial species being least abundant. The dominant forb Jamebrittenia c.f. albanesis was significantly higher (p<0.05) in both slopes (6.65percent) and toplands (7.34percent) than in the valley (3.15). The second most dominant species Puesdognaphalium undulata was significantly higher (p<0.05) in topland areas (6percent) than in valley bottom (3.8percent) and sloppy areas (4.3percent). The results of soil nutrients revealed no significant differences (p>0.05) in the concentration of OC, Ca, and Mg between the communities and seasons. Phosphorus (P) was significantly higher (p<0.05) in winter (concentrations) in most of the sites, except the top sites of Mbizana where summer concentration of P was significantly higher than winter. Potassium (K) was significantly higher (p<0.05) in summer than in winter in most of the HVUs, except the topland areas of Njwaxa and Mbizana sloppy areas where there were no significant differences (p>0.05) in the concentration of K. Soil pH did not display any significant differences (p>0.05) between communities and sites. The mean soil pH recorded in this study was 5.4 implying the soils of Njwaxa and Mbizana communities were acidic. It is evident that communal farmers are well aware of their rangeland condition, changes occurring in their rangelands, their causes and are capable of suggesting some solutions in controlling the declining condition of the rangelands. This study has shown the importance of engaging farmers’ inputs in range assessment since those are people bearing the consequences of rangeland degradation.
- Full Text:
- Date Issued: 2016
- Authors: Ngcofe, Odwa Armstrong
- Date: 2016
- Subjects: Rangelands -- South Africa -- Eastern Cape Land tenure -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13259 , vital:39627
- Description: This study was conducted to determine of rangeland condition in terms of botanical composition, soil nutrient composition, and also to evaluate farmers’ perception on rangeland condition and degradation in two communal villages Njwaxa and Mbizana in the Eastern Cape Province of South Africa in 2014. A Structured questionnaire consisting of close and open-ended questions was used to investigate farmers’ perceptions on range condition, land degradation, and their causes. Fifty households with livestock were randomly selected in two communal areas of Middledrift (i.e. Njwaxa and Mbizana). Respondents of 21 years and above were selected. For assessment of range condition three homogeneous vegetation units (HVU) were demarcated in all study sites, namely slope; valley and toplands were demarcated and sub-divided into four 100m x 50m replicates. In each replicate, four 100m transects were laid parallel to each other 25m apart 1m2 quadrant was systematically located four times along each transect for herbaceous vegetation and soil sampling. The step point method was employed to determine herbaceous species composition and basal cover. A 400m2 belt transect was used to determine woody vegetation composition, density and tree equivalents in each HVU. The germination method was employed for soil seed bank composition and plant density. The soil micro and macro nutrients (N, P, K OC, Ca, Mg, Zn, Cu and Mn) and pH were also analyzed The majority of the respondents were between the ages of 51-60 years. Most of the farmers had more cattle (38percent) than goats (32percent) and sheep (30percent). Livestock numbers were perceived to have declined over the previous 20 years by the majority of respondents (96percent). The respondents indicated that their rangelands were mainly used for browsing (1.37), fire wood (2.01), building and fencing (2.63) and medical purposes (3.66). All the respondents indicated that their rangelands were highly degraded. Sheet erosion (50percent) was perceived to be the major type of soil erosion indicator mentioned by the farmers, followed by gully erosion (29percent) and rill erosion (21percent). The rangeland was dominated by Increaser II (pioneer) (63.2 percent) grass species followed by Decreaser (mesophytes) species (26.3percent). Digitaria eriantha in the valley (53.5 percent) was significantly higher (p<0.05) than both in the top (10.5percent) and sloppy areas (33.5percent) at Njwaxa communal rangeland, the abundance of D. eriantha was significantly higher (p<0.05) than top and valley in Mbizana communal rangeland. The results showed that soil seed banks were dominated by perennials, followed by annuals and biennial species being least abundant. The dominant forb Jamebrittenia c.f. albanesis was significantly higher (p<0.05) in both slopes (6.65percent) and toplands (7.34percent) than in the valley (3.15). The second most dominant species Puesdognaphalium undulata was significantly higher (p<0.05) in topland areas (6percent) than in valley bottom (3.8percent) and sloppy areas (4.3percent). The results of soil nutrients revealed no significant differences (p>0.05) in the concentration of OC, Ca, and Mg between the communities and seasons. Phosphorus (P) was significantly higher (p<0.05) in winter (concentrations) in most of the sites, except the top sites of Mbizana where summer concentration of P was significantly higher than winter. Potassium (K) was significantly higher (p<0.05) in summer than in winter in most of the HVUs, except the topland areas of Njwaxa and Mbizana sloppy areas where there were no significant differences (p>0.05) in the concentration of K. Soil pH did not display any significant differences (p>0.05) between communities and sites. The mean soil pH recorded in this study was 5.4 implying the soils of Njwaxa and Mbizana communities were acidic. It is evident that communal farmers are well aware of their rangeland condition, changes occurring in their rangelands, their causes and are capable of suggesting some solutions in controlling the declining condition of the rangelands. This study has shown the importance of engaging farmers’ inputs in range assessment since those are people bearing the consequences of rangeland degradation.
- Full Text:
- Date Issued: 2016
Bayesian accelerated life tests: exponential and Weibull models
- Authors: Izally, Sharkay Ruwade
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3003 , vital:20351
- Description: Reliability life testing is used for life data analysis in which samples are tested under normal conditions to obtain failure time data for reliability assessment. It can be costly and time consuming to obtain failure time data under normal operating conditions if the mean time to failure of a product is long. An alternative is to use failure time data from an accelerated life test (ALT) to extrapolate the reliability under normal conditions. In accelerated life testing, the units are placed under a higher than normal stress condition such as voltage, current, pressure, temperature, to make the items fail in a shorter period of time. The failure information is then transformed through an accelerated model commonly known as the time transformation function, to predict the reliability under normal operating conditions. The power law will be used as the time transformation function in this thesis. We will first consider a Bayesian inference model under the assumption that the underlying life distribution in the accelerated life test is exponentially distributed. The maximal data information (MDI) prior, the Ghosh Mergel and Liu (GML) prior and the Jeffreys prior will be derived for the exponential distribution. The propriety of the posterior distributions will be investigated. Results will be compared when using these non-informative priors in a simulation study by looking at the posterior variances. The Weibull distribution as the underlying life distribution in the accelerated life test will also be investigated. The maximal data information prior will be derived for the Weibull distribution using the power law. The uniform prior and a mixture of Gamma and uniform priors will be considered. The propriety of these posteriors will also be investigated. The predictive reliability at the use-stress will be computed for these models. The deviance information criterion will be used to compare these priors. As a result of using a time transformation function, Bayesian inference becomes analytically intractable and Markov Chain Monte Carlo (MCMC) methods will be used to alleviate this problem. The Metropolis-Hastings algorithm will be used to sample from the posteriors for the exponential model in the accelerated life test. The adaptive rejection sampling method will be used to sample from the posterior distributions when the Weibull model is considered.
- Full Text:
- Date Issued: 2016
- Authors: Izally, Sharkay Ruwade
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3003 , vital:20351
- Description: Reliability life testing is used for life data analysis in which samples are tested under normal conditions to obtain failure time data for reliability assessment. It can be costly and time consuming to obtain failure time data under normal operating conditions if the mean time to failure of a product is long. An alternative is to use failure time data from an accelerated life test (ALT) to extrapolate the reliability under normal conditions. In accelerated life testing, the units are placed under a higher than normal stress condition such as voltage, current, pressure, temperature, to make the items fail in a shorter period of time. The failure information is then transformed through an accelerated model commonly known as the time transformation function, to predict the reliability under normal operating conditions. The power law will be used as the time transformation function in this thesis. We will first consider a Bayesian inference model under the assumption that the underlying life distribution in the accelerated life test is exponentially distributed. The maximal data information (MDI) prior, the Ghosh Mergel and Liu (GML) prior and the Jeffreys prior will be derived for the exponential distribution. The propriety of the posterior distributions will be investigated. Results will be compared when using these non-informative priors in a simulation study by looking at the posterior variances. The Weibull distribution as the underlying life distribution in the accelerated life test will also be investigated. The maximal data information prior will be derived for the Weibull distribution using the power law. The uniform prior and a mixture of Gamma and uniform priors will be considered. The propriety of these posteriors will also be investigated. The predictive reliability at the use-stress will be computed for these models. The deviance information criterion will be used to compare these priors. As a result of using a time transformation function, Bayesian inference becomes analytically intractable and Markov Chain Monte Carlo (MCMC) methods will be used to alleviate this problem. The Metropolis-Hastings algorithm will be used to sample from the posteriors for the exponential model in the accelerated life test. The adaptive rejection sampling method will be used to sample from the posterior distributions when the Weibull model is considered.
- Full Text:
- Date Issued: 2016
Beta decay of 100/400 Zr produced in neutron-induced fission of natural uranium
- Authors: Kamoto, Thokozani
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3024 , vital:20353
- Description: Fission fragments, produced by neutron bombardment of natural uranium at the Physics Department, Jyväskylä, Finland, are studied in this work. The data had been sorted into 25 Y — y coincidence matrices which were then analysed. In this work we aimed to identify the fission products using Y-Y coincidence analysis and then study the beta-decay of some of the fission products. Sixteen fission products ranging from A = 94 to A = 136 were identified. Out of these fission products beta decay of the A = 100 (100/40 Zr – 100/41 Nb – 100/42 Mo) chain was studied in greater detail. We have also studied the variation of the relative intensities as a function of time of the 159-, 528-, 600-, 768-, 928- and 1502-keV Y-rav lines in 100/42 Mo and the profiles of the relative intensities have been modelled with the variation of the activity of 100/41 Nb against time. Configuration assignments of 100 Zr and 100/42 Mo are discussed.
- Full Text:
- Date Issued: 2016
- Authors: Kamoto, Thokozani
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3024 , vital:20353
- Description: Fission fragments, produced by neutron bombardment of natural uranium at the Physics Department, Jyväskylä, Finland, are studied in this work. The data had been sorted into 25 Y — y coincidence matrices which were then analysed. In this work we aimed to identify the fission products using Y-Y coincidence analysis and then study the beta-decay of some of the fission products. Sixteen fission products ranging from A = 94 to A = 136 were identified. Out of these fission products beta decay of the A = 100 (100/40 Zr – 100/41 Nb – 100/42 Mo) chain was studied in greater detail. We have also studied the variation of the relative intensities as a function of time of the 159-, 528-, 600-, 768-, 928- and 1502-keV Y-rav lines in 100/42 Mo and the profiles of the relative intensities have been modelled with the variation of the activity of 100/41 Nb against time. Configuration assignments of 100 Zr and 100/42 Mo are discussed.
- Full Text:
- Date Issued: 2016
Bio-prospecting a Soil Metagenomic Library for Carbohydrate Active Esterases
- Authors: Shezi, Ntombifuthi
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4172 , http://hdl.handle.net/10962/d1021266
- Description: Lignocellulosic biomass is a promising renewable resource on earth. Plant biomass contains fermentable sugars and other moieties that can be converted to biofuels or other chemicals. Enzymatic hydrolysis of these biopolymers is significant in the liberation of sugars for fermentation into desired products. Owing to its complex structure, synergistic action of enzymes is required for its degradation. Enzymes that are involved in biomass degradation include cellulases, hemicellulases and the accessory enzymes acetyl xylan esterases and ferulic acid esterases. Ferulic acid esterases (FAEs, EC 3.1.1.73), represent a subclass of carboxylester hydrolases (EC 3.1.1.-) that catalyse the release of hydroxycinnamic acids (such as ferulic acid, p-coumaric, ferulic, sinapic and caffeic acid) that are generally found esterified to polysaccharides, such as arabinoxylans. Hydroxycinnamic acids have widespread potential applications due to their antimicrobial, photoprotectant and antioxidant properties, as well as their use as flavour precursors. Therefore, this interesting group of FAEs has a potentially wide variety of applications in agriculture, food and pharmaceutical industries. In the search for novel biocatalysts, metagenomics is considered as an alternative approach to conventional microbe screening, therefore, searching for novel biocatalysts from a soil metagenome that harbours a unique diversity of biocatalyst is significant. The aim of this study was to extract DNA from soil associated with cattle manure and construct a soil metagenomic library using a fosmid based plasmid vector and subsequently functionally screen for ferulic acid esterases using ethyl ferulate as a model substrate. A total of 59 recombinant fosmids conferring ferulic acid esterase phenotypes were identified (Hit rate 1:3122) and the two fosmids that consistently showed high FAE activities were selected for further study. Following nucleotide sequencing and translational analysis, two fae encoding open reading frames (FAE9 and FAE27) of approximately 274 and 322 aa, respectively, were identified. The amino acid sequence of the two ORFs contained a classical conserved esterase/lipase G-x-S-x-G sequence motif. The two genes (fae9 and fae27) were successfully expressed in Escherichia coli BL21 (DE3) and the purified enzymes exhibited respective temperature optima of 50 °C and 40 °C, and respective pH optima of 6.0 and 7.0. Further biochemical characterisation showed that FAE9 and FAE27 have high substrate specificity, following the fact that EFA is the preferred substrate for FAE9 (kcat/Km value of 128 s−1.mM-1) and also the preferred substrate for FAE27 (kcat/Km value of 137 s−1.mM-1). This work proves that soil is a valuable environmental source for novel esterase screening through functional based metagenomic approach. Therefore, this method may be used to screen for other valuable enzymes from environmental sources using inexpensive natural sources to encourage the screening of specific enzymes. Biochemistry of the two isolated enzymes makes these enzymes to be useful in industrial applications due to broad substrate activity that could replace the specialised enzymes to complete plant biomass degradation.
- Full Text:
- Date Issued: 2016
- Authors: Shezi, Ntombifuthi
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4172 , http://hdl.handle.net/10962/d1021266
- Description: Lignocellulosic biomass is a promising renewable resource on earth. Plant biomass contains fermentable sugars and other moieties that can be converted to biofuels or other chemicals. Enzymatic hydrolysis of these biopolymers is significant in the liberation of sugars for fermentation into desired products. Owing to its complex structure, synergistic action of enzymes is required for its degradation. Enzymes that are involved in biomass degradation include cellulases, hemicellulases and the accessory enzymes acetyl xylan esterases and ferulic acid esterases. Ferulic acid esterases (FAEs, EC 3.1.1.73), represent a subclass of carboxylester hydrolases (EC 3.1.1.-) that catalyse the release of hydroxycinnamic acids (such as ferulic acid, p-coumaric, ferulic, sinapic and caffeic acid) that are generally found esterified to polysaccharides, such as arabinoxylans. Hydroxycinnamic acids have widespread potential applications due to their antimicrobial, photoprotectant and antioxidant properties, as well as their use as flavour precursors. Therefore, this interesting group of FAEs has a potentially wide variety of applications in agriculture, food and pharmaceutical industries. In the search for novel biocatalysts, metagenomics is considered as an alternative approach to conventional microbe screening, therefore, searching for novel biocatalysts from a soil metagenome that harbours a unique diversity of biocatalyst is significant. The aim of this study was to extract DNA from soil associated with cattle manure and construct a soil metagenomic library using a fosmid based plasmid vector and subsequently functionally screen for ferulic acid esterases using ethyl ferulate as a model substrate. A total of 59 recombinant fosmids conferring ferulic acid esterase phenotypes were identified (Hit rate 1:3122) and the two fosmids that consistently showed high FAE activities were selected for further study. Following nucleotide sequencing and translational analysis, two fae encoding open reading frames (FAE9 and FAE27) of approximately 274 and 322 aa, respectively, were identified. The amino acid sequence of the two ORFs contained a classical conserved esterase/lipase G-x-S-x-G sequence motif. The two genes (fae9 and fae27) were successfully expressed in Escherichia coli BL21 (DE3) and the purified enzymes exhibited respective temperature optima of 50 °C and 40 °C, and respective pH optima of 6.0 and 7.0. Further biochemical characterisation showed that FAE9 and FAE27 have high substrate specificity, following the fact that EFA is the preferred substrate for FAE9 (kcat/Km value of 128 s−1.mM-1) and also the preferred substrate for FAE27 (kcat/Km value of 137 s−1.mM-1). This work proves that soil is a valuable environmental source for novel esterase screening through functional based metagenomic approach. Therefore, this method may be used to screen for other valuable enzymes from environmental sources using inexpensive natural sources to encourage the screening of specific enzymes. Biochemistry of the two isolated enzymes makes these enzymes to be useful in industrial applications due to broad substrate activity that could replace the specialised enzymes to complete plant biomass degradation.
- Full Text:
- Date Issued: 2016
Biology and ecology of Glossogobius callidus (Smith 1937) in irrigation impoundments in the Sundays River Valley of the Eastern Cape
- Authors: Mofu, Lubabalo
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1136 , vital:20023
- Description: The River Goby Glossogobius callidus (Smith, 1937) is a native abundant fish in both freshwater and estuarine habitats in the Cape Fold Ecoregion, yet little information is available on its life-history. This study aims to contribute to knowledge on the age and growth, reproductive biology and the diet and feeding habits of G. callidus in irrigation impoundments. Glossogobius callidus was sampled monthly from August 2013 till March 2015; from the irrigation ponds in the Sundays River Valley, Eastern Cape Province, South Africa. To determine sex, gonads were visually assessed under a dissecting microscope to confirm the sex based on the shape of the urogenital papillae. Fish were then dissected to confirm sex and gonads were categorised into five macroscopic stages which were histologically validated. Microscopic stages of gonadal development were discerned based on nuclear and cytoplasmic characteristics of the oocyte or sperm. Ovaries and sperms were assigned stages based on the most advanced type of oocyte present. In total 2054 fishes ranging in length from 21.1 mm to 137.2 mm TL were sampled. The sex ratio (1.1 males: 1 females) did not differ from unity (x2 = 0.027, df = 1, p = 0.87). Length at 50% maturity (Lm) was 70 mm TL females and 72 mm TL for males. Spawning season was mid-spring and mid-summer and mean ± S.D absolute fecundity was estimated at 1028.2 ± 131.7 ova/fish. Relative fecundity (number of vitellogenic oocytes per gram of eviscerated fish mass) were estimated at 50 ± 18 ova/fish gram. Otoliths from 560 fish were used for ageing. Growth zone deposition rate was validated using edge analysis. As a unimodal periodic regression model best described the temporal proportion of opaque zone deposition on the edge of otoliths over a one-year period, growth zone deposition rate was validated as annual. The oldest female fish was a 4-year old 84.4 mm TL fish and the oldest male was a 7-year old 100.5 mm TL fish. The length-at-age for the entire population of 560 G. callidus provided von Bertalanffy parameters of Lt = 92 (1 - e -0.58(t + 0.4)) mm TL for the entire population, Lt = 70 (1 - e -1.8 (t + 0.06)) mm TL for males and Lt = 65 (1 - e -1.8 (t + 0.05)) mm TL for females. Converting length at maturity to age at maturity demonstrated that G. callidus attained maturity at an age of 2-years. Growth performance described using the phi-prime index showed that G. callidus had lower growth performance compared to the invasive Neogobius melanostomus. Using age structure, natural mortality was estimated at 1.31 yr-1 using catch curve analysis. Diet of G. callidus comprised of ten taxonomic groups. Among these, aquatic invertebrates were the most diverse group but while relative contribution of the dietary components varied across all size classes and seasons, the key prey items were consistently found in all size classes. These were Diptera, Hemiptera, Trichoptera, Odonata, Cladocera, Copepoda, Hydracarina, Amphipoda, Crustacea, and Mollusca. While dietary differences were observed between the size classes and throughout the seasons, G. callidus can be regarded as a generalist feeder preying on an array of different species. Given its abundance and diet, I suggest that G. callidus contribute considerably to the invertebrate predation pressure in these artificial aquatic environments in an arid region. In summary, medium fecundity, fast growth, moderate maturity, and a generalist feeding behaviour demonstrate that G. callidus is an equilibrium life strategist. In comparison with other species, the life-history traits of G. callidus from irrigation impoundments resemble those of other freshwater goby species, some of which are global invaders.
- Full Text:
- Date Issued: 2016
- Authors: Mofu, Lubabalo
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1136 , vital:20023
- Description: The River Goby Glossogobius callidus (Smith, 1937) is a native abundant fish in both freshwater and estuarine habitats in the Cape Fold Ecoregion, yet little information is available on its life-history. This study aims to contribute to knowledge on the age and growth, reproductive biology and the diet and feeding habits of G. callidus in irrigation impoundments. Glossogobius callidus was sampled monthly from August 2013 till March 2015; from the irrigation ponds in the Sundays River Valley, Eastern Cape Province, South Africa. To determine sex, gonads were visually assessed under a dissecting microscope to confirm the sex based on the shape of the urogenital papillae. Fish were then dissected to confirm sex and gonads were categorised into five macroscopic stages which were histologically validated. Microscopic stages of gonadal development were discerned based on nuclear and cytoplasmic characteristics of the oocyte or sperm. Ovaries and sperms were assigned stages based on the most advanced type of oocyte present. In total 2054 fishes ranging in length from 21.1 mm to 137.2 mm TL were sampled. The sex ratio (1.1 males: 1 females) did not differ from unity (x2 = 0.027, df = 1, p = 0.87). Length at 50% maturity (Lm) was 70 mm TL females and 72 mm TL for males. Spawning season was mid-spring and mid-summer and mean ± S.D absolute fecundity was estimated at 1028.2 ± 131.7 ova/fish. Relative fecundity (number of vitellogenic oocytes per gram of eviscerated fish mass) were estimated at 50 ± 18 ova/fish gram. Otoliths from 560 fish were used for ageing. Growth zone deposition rate was validated using edge analysis. As a unimodal periodic regression model best described the temporal proportion of opaque zone deposition on the edge of otoliths over a one-year period, growth zone deposition rate was validated as annual. The oldest female fish was a 4-year old 84.4 mm TL fish and the oldest male was a 7-year old 100.5 mm TL fish. The length-at-age for the entire population of 560 G. callidus provided von Bertalanffy parameters of Lt = 92 (1 - e -0.58(t + 0.4)) mm TL for the entire population, Lt = 70 (1 - e -1.8 (t + 0.06)) mm TL for males and Lt = 65 (1 - e -1.8 (t + 0.05)) mm TL for females. Converting length at maturity to age at maturity demonstrated that G. callidus attained maturity at an age of 2-years. Growth performance described using the phi-prime index showed that G. callidus had lower growth performance compared to the invasive Neogobius melanostomus. Using age structure, natural mortality was estimated at 1.31 yr-1 using catch curve analysis. Diet of G. callidus comprised of ten taxonomic groups. Among these, aquatic invertebrates were the most diverse group but while relative contribution of the dietary components varied across all size classes and seasons, the key prey items were consistently found in all size classes. These were Diptera, Hemiptera, Trichoptera, Odonata, Cladocera, Copepoda, Hydracarina, Amphipoda, Crustacea, and Mollusca. While dietary differences were observed between the size classes and throughout the seasons, G. callidus can be regarded as a generalist feeder preying on an array of different species. Given its abundance and diet, I suggest that G. callidus contribute considerably to the invertebrate predation pressure in these artificial aquatic environments in an arid region. In summary, medium fecundity, fast growth, moderate maturity, and a generalist feeding behaviour demonstrate that G. callidus is an equilibrium life strategist. In comparison with other species, the life-history traits of G. callidus from irrigation impoundments resemble those of other freshwater goby species, some of which are global invaders.
- Full Text:
- Date Issued: 2016
Business problems facing potential emerging contractors in CIDB grades 5 to 7
- Pretorius, Albertus Johannes Hendrik
- Authors: Pretorius, Albertus Johannes Hendrik
- Date: 2016
- Subjects: Building trades , Project management , Construction industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3459 , vital:20432
- Description: Considering the vital part which the construction industry plays in the economy of South Africa, as well as the objectives of the reconstruction and development thereof, the failure of contractors, despite all the interventions to identify and eradicate the root of the problem, is a matter of great concern. In November 2000, the Construction Industry Development Board Act (2000) was promulgated which led to the inception of the cidb with a mandate to implement an integrated strategy for the reconstruction, growth and development of the construction industry. The matter of contractor development has been widely studied and investigated since the inception of the cidb in 2000. However, the purpose of this study was to focus on the business problems faced by Grade 5 to 7 CE / GB Potential Emerging Contractors, with regard to construction organisations that make the move from small to medium businesses. The intention was to contribute to the successful transition from small to medium businesses by means of structured initiatives. In order to achieve this, a new business strategy must be adopted. It was therefore necessary to extensively consider the surface and core competencies required for making the transition. Liquidity problems that the transition entails were explored, as well as contractor misconceptions with regard to contractor development. In the course of the study, unethical practices and entitlement issues experienced in the built environment and the effect of this on contractor success were explored. The study aimed to recommend a structured framework for co-ordination between assistance, mentorship, contractor needs, client departments, cidb NCDP best practice guidelines and the most important of all, self-empowerment. This study further endeavoured to find possible solutions regarding the assistance requirements, as well as self-empowering objectives for emerging contractors taking the challenging step from small to medium business and by implication, becoming sustainable contractor enterprises in Grades 6 to 8. Political imperatives need to be weighed against the high unemployment rate. The Gross Fixed Capital Formation (GFCF) indicates that there are not enough sustainable contracting opportunities to allocate to Contractor Development Programmes (CDPs). This is aggravated by the tendency that too many hopeful aspirant entrepreneurs, lacking construction surface and core competencies, are seeing the built environment as an easy industry to enter. Just less than 50% of cidb registered contractors exited the register of active contractors during the last ten years ending 2nd quarter 2015. 45% exited during the last five years. This indicates that there is a serious sustainability problem in the built environment. Considering the GFCF contractor opportunities there are too many cidb registered contractors. However, enterprise failure is not only an Emerging Contractor (EC) problem, but occurs across the board. A dangerous notion that the large national construction firms should no longer qualify for public contracts can have disastrous implications for an already embattled industry. Large national firms are the trend setters in the built environment, which coach the much needed construction surface and core competencies. If upgrading is the measure of success the current CDP statistics do not confirm that the strategic objectives of the National Contractor Development Programme (NCDP) are being achieved. All contractors, including black owned contractors, are faring substantially better than their EC counterparts participating in CDPs. Upgrading should carry less weight and sustainability and high performance should become the focus. A serious lack of construction surface and core competencies was identified. If contractor development is the objective the structure of the cidb grading system should be reviewed. It is recommended that the broad CDP hierarchical structure should streamlined and partly privatised to focus on the core strategic objective of contractor development.
- Full Text:
- Date Issued: 2016
- Authors: Pretorius, Albertus Johannes Hendrik
- Date: 2016
- Subjects: Building trades , Project management , Construction industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3459 , vital:20432
- Description: Considering the vital part which the construction industry plays in the economy of South Africa, as well as the objectives of the reconstruction and development thereof, the failure of contractors, despite all the interventions to identify and eradicate the root of the problem, is a matter of great concern. In November 2000, the Construction Industry Development Board Act (2000) was promulgated which led to the inception of the cidb with a mandate to implement an integrated strategy for the reconstruction, growth and development of the construction industry. The matter of contractor development has been widely studied and investigated since the inception of the cidb in 2000. However, the purpose of this study was to focus on the business problems faced by Grade 5 to 7 CE / GB Potential Emerging Contractors, with regard to construction organisations that make the move from small to medium businesses. The intention was to contribute to the successful transition from small to medium businesses by means of structured initiatives. In order to achieve this, a new business strategy must be adopted. It was therefore necessary to extensively consider the surface and core competencies required for making the transition. Liquidity problems that the transition entails were explored, as well as contractor misconceptions with regard to contractor development. In the course of the study, unethical practices and entitlement issues experienced in the built environment and the effect of this on contractor success were explored. The study aimed to recommend a structured framework for co-ordination between assistance, mentorship, contractor needs, client departments, cidb NCDP best practice guidelines and the most important of all, self-empowerment. This study further endeavoured to find possible solutions regarding the assistance requirements, as well as self-empowering objectives for emerging contractors taking the challenging step from small to medium business and by implication, becoming sustainable contractor enterprises in Grades 6 to 8. Political imperatives need to be weighed against the high unemployment rate. The Gross Fixed Capital Formation (GFCF) indicates that there are not enough sustainable contracting opportunities to allocate to Contractor Development Programmes (CDPs). This is aggravated by the tendency that too many hopeful aspirant entrepreneurs, lacking construction surface and core competencies, are seeing the built environment as an easy industry to enter. Just less than 50% of cidb registered contractors exited the register of active contractors during the last ten years ending 2nd quarter 2015. 45% exited during the last five years. This indicates that there is a serious sustainability problem in the built environment. Considering the GFCF contractor opportunities there are too many cidb registered contractors. However, enterprise failure is not only an Emerging Contractor (EC) problem, but occurs across the board. A dangerous notion that the large national construction firms should no longer qualify for public contracts can have disastrous implications for an already embattled industry. Large national firms are the trend setters in the built environment, which coach the much needed construction surface and core competencies. If upgrading is the measure of success the current CDP statistics do not confirm that the strategic objectives of the National Contractor Development Programme (NCDP) are being achieved. All contractors, including black owned contractors, are faring substantially better than their EC counterparts participating in CDPs. Upgrading should carry less weight and sustainability and high performance should become the focus. A serious lack of construction surface and core competencies was identified. If contractor development is the objective the structure of the cidb grading system should be reviewed. It is recommended that the broad CDP hierarchical structure should streamlined and partly privatised to focus on the core strategic objective of contractor development.
- Full Text:
- Date Issued: 2016
Calibration and wide field imaging with PAPER: a catalogue of compact sources
- Authors: Philip, Liju
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2397 , vital:20285
- Description: Observations of the redshifted 21 cm HI line promise to be a formidable tool for cosmology, allowing the investigation of the end of the so-called dark ages, when the first galaxies formed, and the subsequent Epoch of Reionization when the intergalactic medium transitioned from neutral to ionized. Such observations are plagued by foreground emission which is a few orders of magnitude brighter than the 21 cm line. In this thesis I analyzed data from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in order to improve the characterization of the extragalactic foreground component. I derived a catalogue of unresolved radio sources down to a 5 Jy flux density limit at 150 MHz and derived their spectral index distribution using literature data at 408 MHz. I implemented advanced techniques to calibrate radio interferometric data that led to a few percent accuracy on the flux density scale of the derived catalogue. This work, therefore, represents a further step towards creating an accurate, global sky model that is crucial to improve calibration of Epoch of Reionization observations.
- Full Text:
- Date Issued: 2016
- Authors: Philip, Liju
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2397 , vital:20285
- Description: Observations of the redshifted 21 cm HI line promise to be a formidable tool for cosmology, allowing the investigation of the end of the so-called dark ages, when the first galaxies formed, and the subsequent Epoch of Reionization when the intergalactic medium transitioned from neutral to ionized. Such observations are plagued by foreground emission which is a few orders of magnitude brighter than the 21 cm line. In this thesis I analyzed data from the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) in order to improve the characterization of the extragalactic foreground component. I derived a catalogue of unresolved radio sources down to a 5 Jy flux density limit at 150 MHz and derived their spectral index distribution using literature data at 408 MHz. I implemented advanced techniques to calibrate radio interferometric data that led to a few percent accuracy on the flux density scale of the derived catalogue. This work, therefore, represents a further step towards creating an accurate, global sky model that is crucial to improve calibration of Epoch of Reionization observations.
- Full Text:
- Date Issued: 2016
Characterisation of selected municipal organic waste for energy conversion through gasification
- Authors: Ngubelanga, Nolitha
- Date: 2016
- Subjects: Biomass gasification Sewage -- Purification Biomass energy Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/11020 , vital:36682
- Description: Biomass gasification has become a study of great interest over the years and plant biomass with cellulose, hemicellulose, and lignin found to be an ideal resource for conversion into heat and power through thermochemical processes such as gasification. The inadequate supply of the energy in the country has become critical with the national energy provider struggling to meet the energy demands of the ever growing population of South Africa. The depletion of natural resources and the unstable prices as well as the cost of transporting the fuels together with the environmental effects of burning fossil fuels are contributing factors to the energy crisis. Alternative sources of energy that are locally available, sustainable, and environmentally friendly are presently in demand as municipal organic wastes has been considered a source of renewable energy with gasification deemed one of the leading edge technologies to harness the energy. This research only studied the characteristics and kinetics of selected municipal organic waste including decaying wood, tomatoes, onions, cabbage, butternut and bones. The research did not involve the gasification process because of expenses associated with gasification processes, however, this has been considered as future studies under the conditions of available resources to carry out the actual gasification experiments. The characteristics of selected municipal organic wastes for energy conversion through gasification were actually investigated in this study and the implication of the value of each property interpreted in relation to gasification with specific reference to information available in the literature. Proximate analysis conducted on the wastes indicate that the physical properties in terms of the weight percentages of moisture, volatile matter fixed carbon and ash contents of the wastes vary considerably, especially with regards to the last three properties. The reason for this wide variation was attributed to the source of the wastes and the standard of living of the people vi in the area where the wastes were collected. However, the values obtained for these properties are within limits for the wastes to be adequately used as feedstocks in a gasification process, except for their content of ash, which was significantly high in all of the wastes for the aforementioned reasons. The ultimate analysis of the wastes as determined using the Energy Dispersive X-ray spectroscopy gave the percentage composition of the chemical elements present in the wastes, which suggest that carbon is the chief elemental constituent of the wastes. The highest carbon content of about 47% was recorded for bone due again to the reasons previously adduced. According to McKendry, 2002, the high carbon content of the wastes implies increased calorific value as well as increased gas production during gasification. A number of ash–forming elements were also found in the wastes, which included magnesium and potassium in low concentrations that does not pose any technical challenges during gasification, although their concentration may increase under high temperature gasification, which may equally result to some catalytic effect that would contribute to the overall gasification efficiency (Anukam et al., 2016). Calorific value analysis also suggests that the wastes contain reasonable amount of energy that can be converted to useful energy through gasification. Although, variation in calorific value was also noted, the highest calorific value of about 18 MJ/kg was recoded for bones, which correlates its data on the highest carbon content of all wastes. However, the data on the calorific value of the wastes suggests that the wastes are well suited for gasification by virtue of their calorific value. FTIR analysis revealed the major functional groups present in the internal structure of the wastes. The common functional groups observed were the OH group found in the band around 3600–3400cm-1 for most of the wastes; the C–H stretching band at 2970-2780 cm-1; and the C–O as well as the C–O–C observed in the region of 1740–1710 cm-1 and 1250-1220 cm-1 for all samples, respectively. Most functional group in the internal structures of gasification feedstocks function to facilitate faster vii rates of reaction and consequently faster rates of gasification that contributes to optimum efficiency under any conditions of gasification (Anukam et al., 2016). While thermogravimetric analysis established thermal parameters that are likely to have positive influence on the gasification of the wastes, kinetic investigation revealed two parameters that may also impact on the gasification of the wastes. These are activation energy and pre–exponential factor, which were found to be in good agreement with the values obtained in the literature even though variation in these parameters was noted. The values obtained for activation energy and pre–exponential factor using the Kissinger method of kinetic analysis showed a far less value for these two parameters when compared to commonly used feedstocks like wood and coal. This was a reason attributed to the chemical characteristics of the wastes, mainly their lower content of carbon compared to these two (wood and coal) commonly used fuels.
- Full Text:
- Date Issued: 2016
- Authors: Ngubelanga, Nolitha
- Date: 2016
- Subjects: Biomass gasification Sewage -- Purification Biomass energy Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/11020 , vital:36682
- Description: Biomass gasification has become a study of great interest over the years and plant biomass with cellulose, hemicellulose, and lignin found to be an ideal resource for conversion into heat and power through thermochemical processes such as gasification. The inadequate supply of the energy in the country has become critical with the national energy provider struggling to meet the energy demands of the ever growing population of South Africa. The depletion of natural resources and the unstable prices as well as the cost of transporting the fuels together with the environmental effects of burning fossil fuels are contributing factors to the energy crisis. Alternative sources of energy that are locally available, sustainable, and environmentally friendly are presently in demand as municipal organic wastes has been considered a source of renewable energy with gasification deemed one of the leading edge technologies to harness the energy. This research only studied the characteristics and kinetics of selected municipal organic waste including decaying wood, tomatoes, onions, cabbage, butternut and bones. The research did not involve the gasification process because of expenses associated with gasification processes, however, this has been considered as future studies under the conditions of available resources to carry out the actual gasification experiments. The characteristics of selected municipal organic wastes for energy conversion through gasification were actually investigated in this study and the implication of the value of each property interpreted in relation to gasification with specific reference to information available in the literature. Proximate analysis conducted on the wastes indicate that the physical properties in terms of the weight percentages of moisture, volatile matter fixed carbon and ash contents of the wastes vary considerably, especially with regards to the last three properties. The reason for this wide variation was attributed to the source of the wastes and the standard of living of the people vi in the area where the wastes were collected. However, the values obtained for these properties are within limits for the wastes to be adequately used as feedstocks in a gasification process, except for their content of ash, which was significantly high in all of the wastes for the aforementioned reasons. The ultimate analysis of the wastes as determined using the Energy Dispersive X-ray spectroscopy gave the percentage composition of the chemical elements present in the wastes, which suggest that carbon is the chief elemental constituent of the wastes. The highest carbon content of about 47% was recorded for bone due again to the reasons previously adduced. According to McKendry, 2002, the high carbon content of the wastes implies increased calorific value as well as increased gas production during gasification. A number of ash–forming elements were also found in the wastes, which included magnesium and potassium in low concentrations that does not pose any technical challenges during gasification, although their concentration may increase under high temperature gasification, which may equally result to some catalytic effect that would contribute to the overall gasification efficiency (Anukam et al., 2016). Calorific value analysis also suggests that the wastes contain reasonable amount of energy that can be converted to useful energy through gasification. Although, variation in calorific value was also noted, the highest calorific value of about 18 MJ/kg was recoded for bones, which correlates its data on the highest carbon content of all wastes. However, the data on the calorific value of the wastes suggests that the wastes are well suited for gasification by virtue of their calorific value. FTIR analysis revealed the major functional groups present in the internal structure of the wastes. The common functional groups observed were the OH group found in the band around 3600–3400cm-1 for most of the wastes; the C–H stretching band at 2970-2780 cm-1; and the C–O as well as the C–O–C observed in the region of 1740–1710 cm-1 and 1250-1220 cm-1 for all samples, respectively. Most functional group in the internal structures of gasification feedstocks function to facilitate faster vii rates of reaction and consequently faster rates of gasification that contributes to optimum efficiency under any conditions of gasification (Anukam et al., 2016). While thermogravimetric analysis established thermal parameters that are likely to have positive influence on the gasification of the wastes, kinetic investigation revealed two parameters that may also impact on the gasification of the wastes. These are activation energy and pre–exponential factor, which were found to be in good agreement with the values obtained in the literature even though variation in these parameters was noted. The values obtained for activation energy and pre–exponential factor using the Kissinger method of kinetic analysis showed a far less value for these two parameters when compared to commonly used feedstocks like wood and coal. This was a reason attributed to the chemical characteristics of the wastes, mainly their lower content of carbon compared to these two (wood and coal) commonly used fuels.
- Full Text:
- Date Issued: 2016
Characterisation of the production and consumption of milk in the communal livestock production sector of the Eastern Cape Province, South Africa
- Authors: Kumbirai, Kaguru Tinashe
- Date: 2016
- Subjects: Milk consumption -- South Africa -- Eastern Cape Dairy farming -- Economic aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/3066 , vital:28251
- Description: The study was conducted in Eastern Cape Province, South Africa with the objective of characterising milk production and consumption among the communal households. A pretested semi-structured questionnaire was used to collect data through a single visit survey between June 2014 and May 2015. The study was undertaken in five randomly selected communal districts using a multi – stage area probability sampling method. Household sample size was calculated using a statistical methodology through a fixed formula based on a rural population size of 4410000, at a confidence level of 95 percent. A total of 500 households were selected with a sample size of 20 households in 5 communities within five different communal districts within the province. Half of the total sample size was used to represent the number of non-milk producing households (250) to get a true reflection on consumption profiles for nonproducers. Across the province the average communal family size was between 5-10 members with a monthly income of ZAR1340 per household. On average, pasture land size of the sampled households was 1 ha, with a range of 0.25-1.7 ha. The numbers of animals per species found in the studied province was highest for sheep (310) followed by cattle (227) and goat (87). Average livestock holding per household in the study area was 9.85 TLU (Tropical Livestock Unit). According to the respondents the predominant milking livestock numbers were between 1-3 animals milking per household. In the studied area traditional hand milking of livestock was the major milking practices at 12 percent in goats, 15 percent in sheep and 45 percent in cattle milk production. Consumption was the predominant reason for milk production recorded at 27 percent across the province. Milk production was 43 percent most preferred in cattle followed by 32 percent in goat and least at 29 percent in sheep across the province. In general, from the study it was noted that the majority (38 percent) of the respondents across the province indicated 0-5mins as the time it took to milk most milk producing livestock. The majority of the milking practices was done (37 percent) predominantly once a day, followed by 2 percent twice daily across the province. The daily milk production was on average (0.45±1.07) 2-5 litre in cattle, (4.86±0.814) 0-1litre in goats and (2.62±0.42) 0-1 litre sheep per producing house hold with in the province The monthly raw milk consumption in the province was (2.20± 1.42) 2-5 litres of cattle milk, (4.78±0.79) 2-5 litres of goat milk and (4.98±0.69) 2-5 litres of sheep milk per consuming household.
- Full Text:
- Date Issued: 2016
- Authors: Kumbirai, Kaguru Tinashe
- Date: 2016
- Subjects: Milk consumption -- South Africa -- Eastern Cape Dairy farming -- Economic aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/3066 , vital:28251
- Description: The study was conducted in Eastern Cape Province, South Africa with the objective of characterising milk production and consumption among the communal households. A pretested semi-structured questionnaire was used to collect data through a single visit survey between June 2014 and May 2015. The study was undertaken in five randomly selected communal districts using a multi – stage area probability sampling method. Household sample size was calculated using a statistical methodology through a fixed formula based on a rural population size of 4410000, at a confidence level of 95 percent. A total of 500 households were selected with a sample size of 20 households in 5 communities within five different communal districts within the province. Half of the total sample size was used to represent the number of non-milk producing households (250) to get a true reflection on consumption profiles for nonproducers. Across the province the average communal family size was between 5-10 members with a monthly income of ZAR1340 per household. On average, pasture land size of the sampled households was 1 ha, with a range of 0.25-1.7 ha. The numbers of animals per species found in the studied province was highest for sheep (310) followed by cattle (227) and goat (87). Average livestock holding per household in the study area was 9.85 TLU (Tropical Livestock Unit). According to the respondents the predominant milking livestock numbers were between 1-3 animals milking per household. In the studied area traditional hand milking of livestock was the major milking practices at 12 percent in goats, 15 percent in sheep and 45 percent in cattle milk production. Consumption was the predominant reason for milk production recorded at 27 percent across the province. Milk production was 43 percent most preferred in cattle followed by 32 percent in goat and least at 29 percent in sheep across the province. In general, from the study it was noted that the majority (38 percent) of the respondents across the province indicated 0-5mins as the time it took to milk most milk producing livestock. The majority of the milking practices was done (37 percent) predominantly once a day, followed by 2 percent twice daily across the province. The daily milk production was on average (0.45±1.07) 2-5 litre in cattle, (4.86±0.814) 0-1litre in goats and (2.62±0.42) 0-1 litre sheep per producing house hold with in the province The monthly raw milk consumption in the province was (2.20± 1.42) 2-5 litres of cattle milk, (4.78±0.79) 2-5 litres of goat milk and (4.98±0.69) 2-5 litres of sheep milk per consuming household.
- Full Text:
- Date Issued: 2016
Characterization of various garden grass species for energy conversion in a down draft biomass gasifier
- Authors: Mkosi, Lungisa
- Date: 2016
- Subjects: Biomass energy Greenhouse gases Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5817 , vital:29399
- Description: Energy plays a vital role in socio-economic development and raising living standards of human beings. The overreliance on fossil fuels results in the depletion of fossil fuels as well as environmental pollution from the green-house gases that result from the use of fossil fuels. Biomass feedstock are able to ameliorate this situation by utilizing the CO2 that has been used by plants during photosynthesis. This study investigated the suitability of the three garden grass species (Chloris gayana, Cynodon dactylon and Pennisetum clandestum) as biomass feedstock for gasification purposes. The three garden grass species were collected at the Alice Campus of the University of Fort Hare. These grass species were characterized using elemental analyser (CHNS), FT-IR, EDX and TGA. The Activation energy (Ea) of the three grass species were 48.22 kJ/mol for P. clandestum, 36.8 kJ/mol for C. gayana and 258 kJ/mol for C. dactylon. Of the three grass species, C. gayana had the lowest Activation energy of 36.8 kJ/mol and also had the highest maximum efficiency of 69 percent compared to 65.3 percent for P. clandestum and 63.5 percent for C. dactylon. Actual gasification was not carried out but the results on maximum efficiency were obtained from computer simulation of gasification.
- Full Text:
- Date Issued: 2016
- Authors: Mkosi, Lungisa
- Date: 2016
- Subjects: Biomass energy Greenhouse gases Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5817 , vital:29399
- Description: Energy plays a vital role in socio-economic development and raising living standards of human beings. The overreliance on fossil fuels results in the depletion of fossil fuels as well as environmental pollution from the green-house gases that result from the use of fossil fuels. Biomass feedstock are able to ameliorate this situation by utilizing the CO2 that has been used by plants during photosynthesis. This study investigated the suitability of the three garden grass species (Chloris gayana, Cynodon dactylon and Pennisetum clandestum) as biomass feedstock for gasification purposes. The three garden grass species were collected at the Alice Campus of the University of Fort Hare. These grass species were characterized using elemental analyser (CHNS), FT-IR, EDX and TGA. The Activation energy (Ea) of the three grass species were 48.22 kJ/mol for P. clandestum, 36.8 kJ/mol for C. gayana and 258 kJ/mol for C. dactylon. Of the three grass species, C. gayana had the lowest Activation energy of 36.8 kJ/mol and also had the highest maximum efficiency of 69 percent compared to 65.3 percent for P. clandestum and 63.5 percent for C. dactylon. Actual gasification was not carried out but the results on maximum efficiency were obtained from computer simulation of gasification.
- Full Text:
- Date Issued: 2016
Classical and quantum picture of the interior of two-dimensional black holes
- Authors: Shawa, Mark
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3629 , vital:20531
- Description: A quantum-mechanical description of black holes would represent the final step in our understanding of the nature of space-time. However, any progress towards that end is usually foiled by persistent space-time singularities that exist at the center of black holes. From the four-dimensional point of view, black holes seem to resist quantization. Under highly symmetric conditions, all higher-dimensional black holes are two-dimensional. Unlike their higher-dimensional counterparts, two dimensional black holes may not resist quantization. A non-trivial description of gravity in two dimensions is not possible using Einstein’s theory of gravity alone. However, we may still arrive at a consistent description of gravity by introducing a scalar field known as the dilaton. In this thesis, we study both the classical and quantum aspects of the interior of two-dimensional black holes using a generalized dilaton-gravity theory. Classically, we will find that the interior of most two-dimensional black holes is not much different from that of four-dimensional black holes. But by introducing quantized matter into the theory, the fluctuations in space-time will give a different picture of the structure of interior of black holes. Using a low-energy effective field theory, we will show that it is indeed possible to identify quantum modes in the interior of black holes and perform quantum-mechanical calculations near the singularity.
- Full Text:
- Date Issued: 2016
- Authors: Shawa, Mark
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3629 , vital:20531
- Description: A quantum-mechanical description of black holes would represent the final step in our understanding of the nature of space-time. However, any progress towards that end is usually foiled by persistent space-time singularities that exist at the center of black holes. From the four-dimensional point of view, black holes seem to resist quantization. Under highly symmetric conditions, all higher-dimensional black holes are two-dimensional. Unlike their higher-dimensional counterparts, two dimensional black holes may not resist quantization. A non-trivial description of gravity in two dimensions is not possible using Einstein’s theory of gravity alone. However, we may still arrive at a consistent description of gravity by introducing a scalar field known as the dilaton. In this thesis, we study both the classical and quantum aspects of the interior of two-dimensional black holes using a generalized dilaton-gravity theory. Classically, we will find that the interior of most two-dimensional black holes is not much different from that of four-dimensional black holes. But by introducing quantized matter into the theory, the fluctuations in space-time will give a different picture of the structure of interior of black holes. Using a low-energy effective field theory, we will show that it is indeed possible to identify quantum modes in the interior of black holes and perform quantum-mechanical calculations near the singularity.
- Full Text:
- Date Issued: 2016
Comparative analysis of characteristics of the various sugarcane bagasse types in terms of gasification
- Authors: Kula, Mpumezo
- Date: 2016
- Subjects: Bagasse Sugarcane -- Breeding Coal gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13392 , vital:39656
- Description: The insight that the fossil fuel reserves are limited, together with concerns over security of supply (i.e. the oil crises), initiated the first raise of interest in biomass and all other renewable energy forms. However, the concern grew that global warming and the resulting climate change were enhanced by carbon dioxide (CO2) emissions resulting from fossil fuel consumption. Meanwhile, biomass energy is thought to account for 14–15percent of total world energy consumption. Hence, the exploitation and utilization of biomass energy are effective and necessary for relieving the pressures caused by environmental pollution and fossil fuel shortage (Lv et al., 2010). Recently, extensive research aimed at converting biomass to useful energy have been carried out, especially pyrolysis and gasification, which are particularly suitable for the effective and efficient utilization of biomass. Sugarcane bagasse is the main byproduct of sugarcane mill, ready available at the production site so that it may be a suitable raw material for the production of biofuels, chemicals, and electricity. Among the methods that have been previously studied, is this particular study we explore thermochemical process, gasification. The properties of sugarcane bagasse relevant to gasification are briefly reviewed. The compositions of the bagasse as a fuel are variable, especially with respect to inorganic constituents important to the critical problems of sintering, fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, are responsible for many undesirable reactions in a gasifier system. The three sugarcane bagasse types namely washed, unwashed and the depithed sugarcane bagasse were subjected in different types of characterization to review and compare their characteristics for gasification. Ultimate analysis was used to determine the elemental compositions and this was helpful in estimating the energy input of the materials. Elemental compositions were determined with the CHNS analyzer which gave the percent compositions of each fuel in terms of Carbon, Hydrogen, Nitrogen, Sulphur as well as Oxygen (by difference) and the SEM/EDX which gave the elemental composition of the materials as can be viewed from the EDX. The proximate analysis which is the physical characterization of the materials was carried out to preview the behavior of the sugarcane bagasse when subjected into high temperatures as the gasification process uses very high temperatures. These were determined by the TGA and the volatile matter content; fixed carbon content, moisture content and ash content were extrapolated from the resulting thermogram. SEM images for surface structures of the bagasse and FTIR for the structural functionality and bonding structures. The characterization of the bagasse was conducted to compare their gasification properties.
- Full Text:
- Date Issued: 2016
- Authors: Kula, Mpumezo
- Date: 2016
- Subjects: Bagasse Sugarcane -- Breeding Coal gasification
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13392 , vital:39656
- Description: The insight that the fossil fuel reserves are limited, together with concerns over security of supply (i.e. the oil crises), initiated the first raise of interest in biomass and all other renewable energy forms. However, the concern grew that global warming and the resulting climate change were enhanced by carbon dioxide (CO2) emissions resulting from fossil fuel consumption. Meanwhile, biomass energy is thought to account for 14–15percent of total world energy consumption. Hence, the exploitation and utilization of biomass energy are effective and necessary for relieving the pressures caused by environmental pollution and fossil fuel shortage (Lv et al., 2010). Recently, extensive research aimed at converting biomass to useful energy have been carried out, especially pyrolysis and gasification, which are particularly suitable for the effective and efficient utilization of biomass. Sugarcane bagasse is the main byproduct of sugarcane mill, ready available at the production site so that it may be a suitable raw material for the production of biofuels, chemicals, and electricity. Among the methods that have been previously studied, is this particular study we explore thermochemical process, gasification. The properties of sugarcane bagasse relevant to gasification are briefly reviewed. The compositions of the bagasse as a fuel are variable, especially with respect to inorganic constituents important to the critical problems of sintering, fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, are responsible for many undesirable reactions in a gasifier system. The three sugarcane bagasse types namely washed, unwashed and the depithed sugarcane bagasse were subjected in different types of characterization to review and compare their characteristics for gasification. Ultimate analysis was used to determine the elemental compositions and this was helpful in estimating the energy input of the materials. Elemental compositions were determined with the CHNS analyzer which gave the percent compositions of each fuel in terms of Carbon, Hydrogen, Nitrogen, Sulphur as well as Oxygen (by difference) and the SEM/EDX which gave the elemental composition of the materials as can be viewed from the EDX. The proximate analysis which is the physical characterization of the materials was carried out to preview the behavior of the sugarcane bagasse when subjected into high temperatures as the gasification process uses very high temperatures. These were determined by the TGA and the volatile matter content; fixed carbon content, moisture content and ash content were extrapolated from the resulting thermogram. SEM images for surface structures of the bagasse and FTIR for the structural functionality and bonding structures. The characterization of the bagasse was conducted to compare their gasification properties.
- Full Text:
- Date Issued: 2016
Comparative analysis of characteristics of the various sugarcane bagasse types in terms of gasification
- Authors: Kula, Mpumezo
- Date: 2016
- Subjects: Bagasse Bioenergetics Sugarcane -- Breeding Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/1929 , vital:27584
- Description: The insight that the fossil fuel reserves are limited, together with concerns over security of supply (i.e. the oil crises), initiated the first raise of interest in biomass and all other renewable energy forms. However, the concern grew that global warming and the resulting climate change were enhanced by carbon dioxide (CO2) emissions resulting from fossil fuel consumption. Meanwhile, biomass energy is thought to account for 14–15% of total world energy consumption. Hence, the exploitation and utilization of biomass energy are effective and necessary for relieving the pressures caused by environmental pollution and fossil fuel shortage (Lv et al., 2010). Recently, extensive research aimed at converting biomass to useful energy have been carried out, especially pyrolysis and gasification, which are particularly suitable for the effective and efficient utilization of biomass. Sugarcane bagasse is the main byproduct of sugarcane mill, ready available at the production site so that it may be a suitable raw material for the production of biofuels, chemicals, and electricity. Among the methods that have been previously studied, is this particular study we explore thermochemical process, gasification. The properties of sugarcane bagasse relevant to gasification are briefly reviewed. The compositions of the bagasse as a fuel are variable, especially with respect to inorganic constituents important to the critical problems of sintering, fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, are responsible for many undesirable reactions in a gasifier system.
- Full Text:
- Date Issued: 2016
- Authors: Kula, Mpumezo
- Date: 2016
- Subjects: Bagasse Bioenergetics Sugarcane -- Breeding Solar energy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/1929 , vital:27584
- Description: The insight that the fossil fuel reserves are limited, together with concerns over security of supply (i.e. the oil crises), initiated the first raise of interest in biomass and all other renewable energy forms. However, the concern grew that global warming and the resulting climate change were enhanced by carbon dioxide (CO2) emissions resulting from fossil fuel consumption. Meanwhile, biomass energy is thought to account for 14–15% of total world energy consumption. Hence, the exploitation and utilization of biomass energy are effective and necessary for relieving the pressures caused by environmental pollution and fossil fuel shortage (Lv et al., 2010). Recently, extensive research aimed at converting biomass to useful energy have been carried out, especially pyrolysis and gasification, which are particularly suitable for the effective and efficient utilization of biomass. Sugarcane bagasse is the main byproduct of sugarcane mill, ready available at the production site so that it may be a suitable raw material for the production of biofuels, chemicals, and electricity. Among the methods that have been previously studied, is this particular study we explore thermochemical process, gasification. The properties of sugarcane bagasse relevant to gasification are briefly reviewed. The compositions of the bagasse as a fuel are variable, especially with respect to inorganic constituents important to the critical problems of sintering, fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, are responsible for many undesirable reactions in a gasifier system.
- Full Text:
- Date Issued: 2016
Comparative analysis of existing pipelines for assessment of arbuscular mycorrhizal fungal biodiversity in natural and commercial rooibos (aspalathus linearis) and honeybush (cyclopia intermedia) soil samples
- Authors: De Wit, Hermina Johanna
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2915 , vital:20342
- Full Text:
- Date Issued: 2016
- Authors: De Wit, Hermina Johanna
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2915 , vital:20342
- Full Text:
- Date Issued: 2016
Construction project manager health and safety interventions towards improving workers' performance
- Authors: Ayessaki, Winn-Yam Houdou
- Date: 2016
- Subjects: Construction industry -- Management -- Health aspects Construction workers -- Health aspects -- South Africa Construction workers -- Safety measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12275 , vital:27050
- Description: Optimum construction worker (CW) performance is required to achieve project delivery within project parameters. It is not always the case as CWs are regularly exposed to hazards, involved in accidents, their productivity is poor, they suffer from ill health, suffer from work-related musculoskeletal disorders (WMSDs) and contractors lack resources to allocate towards H&S. However, the lack or the absence of health and safety (H&S) measures, which the aforementioned depend on, has a negative impact on workers’ performance. Two descriptive surveys were conducted among professional construction project managers (CPMs) registered with the South African Council for Project and Construction Management Professions (SACPCMP) and general contractors (GCs) registered with the East Cape Master Builders Association (ECMBA). Interviews were also conducted with CPMs registered with the SACPCMP residing in the Nelson Mandela Bay metropolitan area. The salient findings include: • Accidents, which occur on construction sites, impact workers’ performance; • Inadequate H&S implementation affects both CW skills and motivation, which in turn affects their performance; • Poor constructability is relevant to H&S and CWs’ skills; • Provision and maintenance of welfare facilities are commonly inadequate and affect workers’ performance, and • Projects do not benefit from the adequate financial provision for H&S. It was concluded that exposure to hazards, poor site conditions, inadequate provision of welfare facilities, WMSDs, and insufficient financial provision for H&S affect workers’ performance by either incapacitating or demotivating them. Recommendations include : CPMs should make better use of their influence on clients; they should improve communication channels between project stakeholders; legislators need to raise awareness regarding H&S and worker welfare, and training and education institutions need to empower workers and professionals with H&S knowledge.
- Full Text:
- Date Issued: 2016
- Authors: Ayessaki, Winn-Yam Houdou
- Date: 2016
- Subjects: Construction industry -- Management -- Health aspects Construction workers -- Health aspects -- South Africa Construction workers -- Safety measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/12275 , vital:27050
- Description: Optimum construction worker (CW) performance is required to achieve project delivery within project parameters. It is not always the case as CWs are regularly exposed to hazards, involved in accidents, their productivity is poor, they suffer from ill health, suffer from work-related musculoskeletal disorders (WMSDs) and contractors lack resources to allocate towards H&S. However, the lack or the absence of health and safety (H&S) measures, which the aforementioned depend on, has a negative impact on workers’ performance. Two descriptive surveys were conducted among professional construction project managers (CPMs) registered with the South African Council for Project and Construction Management Professions (SACPCMP) and general contractors (GCs) registered with the East Cape Master Builders Association (ECMBA). Interviews were also conducted with CPMs registered with the SACPCMP residing in the Nelson Mandela Bay metropolitan area. The salient findings include: • Accidents, which occur on construction sites, impact workers’ performance; • Inadequate H&S implementation affects both CW skills and motivation, which in turn affects their performance; • Poor constructability is relevant to H&S and CWs’ skills; • Provision and maintenance of welfare facilities are commonly inadequate and affect workers’ performance, and • Projects do not benefit from the adequate financial provision for H&S. It was concluded that exposure to hazards, poor site conditions, inadequate provision of welfare facilities, WMSDs, and insufficient financial provision for H&S affect workers’ performance by either incapacitating or demotivating them. Recommendations include : CPMs should make better use of their influence on clients; they should improve communication channels between project stakeholders; legislators need to raise awareness regarding H&S and worker welfare, and training and education institutions need to empower workers and professionals with H&S knowledge.
- Full Text:
- Date Issued: 2016
Construction small and medium enterprise development
- Authors: Mbambe, Putumani
- Date: 2016
- Subjects: Construction industry -- Management Small business -- South Africa -- Port Elizabeth Building -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11681 , vital:26950
- Description: The objective of this treatise study was to determine the leading causes which limit the development of SMME contractors, to ascertain the accessibility of SMME incubators available to support SMME development and to identify the cause of poor management performance by SMME contractors based in the Nelson Mandela Bay Metropolitan Municipality. A qualitative method was adopted for this study. The primary data was collected using a structured interview guide which incorporated the sub problems and the research questions. The salient findings of this study are: SMME contractors are unaware of the available business information and government support programmes designed to assist them; SMME contractors do not receive capital from banks when they don‟t have collateral; Desperation to secure projects among SMME contractors is the leading cause for under-pricing; SMME contractors are still paid later than the 30 day period for completed work; SMME owners who had started their construction companies lacked training and do not have the relevant experience and knowledge required to manage a construction company. In summary the study concluded that SMME who have access to capital have high growth prospects than those that have not. Accessibility to information and awareness of available opportunities remains significant for the growth of SMMEs. Construction related knowledge and training for SMME owners contributes vastly to the success of SMME companies. The study recommended that; Government needs to promote the accessibility of SMME incubators and ensure institutions designed to assist SMMEs with finance are accessible; The effectiveness of current development programs for small enterprises and skills development programs should be reviewed; MMBM should setup a mentoring program to help train SMME contractors theoretically and practically; NMBM local government should promote women to own SMMEs in order to close the gap of inequality in the built environment; Banks must work with government institutions to ensure that they are able to fund SMMEs.
- Full Text:
- Date Issued: 2016
- Authors: Mbambe, Putumani
- Date: 2016
- Subjects: Construction industry -- Management Small business -- South Africa -- Port Elizabeth Building -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/11681 , vital:26950
- Description: The objective of this treatise study was to determine the leading causes which limit the development of SMME contractors, to ascertain the accessibility of SMME incubators available to support SMME development and to identify the cause of poor management performance by SMME contractors based in the Nelson Mandela Bay Metropolitan Municipality. A qualitative method was adopted for this study. The primary data was collected using a structured interview guide which incorporated the sub problems and the research questions. The salient findings of this study are: SMME contractors are unaware of the available business information and government support programmes designed to assist them; SMME contractors do not receive capital from banks when they don‟t have collateral; Desperation to secure projects among SMME contractors is the leading cause for under-pricing; SMME contractors are still paid later than the 30 day period for completed work; SMME owners who had started their construction companies lacked training and do not have the relevant experience and knowledge required to manage a construction company. In summary the study concluded that SMME who have access to capital have high growth prospects than those that have not. Accessibility to information and awareness of available opportunities remains significant for the growth of SMMEs. Construction related knowledge and training for SMME owners contributes vastly to the success of SMME companies. The study recommended that; Government needs to promote the accessibility of SMME incubators and ensure institutions designed to assist SMMEs with finance are accessible; The effectiveness of current development programs for small enterprises and skills development programs should be reviewed; MMBM should setup a mentoring program to help train SMME contractors theoretically and practically; NMBM local government should promote women to own SMMEs in order to close the gap of inequality in the built environment; Banks must work with government institutions to ensure that they are able to fund SMMEs.
- Full Text:
- Date Issued: 2016