The investigation of alternative processes for the oxidation of phenol
- Authors: Pongoma, Basanda
- Date: 2010
- Subjects: Phenol , Hydroquinone
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10381 , http://hdl.handle.net/10948/1479 , Phenol , Hydroquinone
- Description: The electrochemical oxidation of phenol can be considered as an important process for either producing value added products such as hydroquinone and catechol or for the removal of the phenol from waste water streams to form carbon dioxide. This process had been extensively studied with the main focus on type of anode material used. Even though the anode material could be made from a range of materials, this study focused on using PbO2 as anode material that was made by using Pb-acid battery principles in designing a microporous electrode. In this study, the focus was on using lead dioxide as an anode material that was made by using the formation principles used in the manufacturing of Pb-acid batteries. This allowed for the construction of an electrochemical flow-through micro-porous reactor that contained PbO2 as the anode and Pb as the cathode, allowing for a solution containing phenol to flow through the cell continuously. By applying a suitable potential across the cell, the almost complete oxidation of phenol would occur to form benzoquinone, which was followed by the sequential reduction to other products such as hydroquinone and catechol. The system was shown to be made up of tightly packed micro-porous material that had a very high surface area-to-volume ratio. The study showed that between 80 to 90 percent successful conversion of a 50 mM solution of phenol could be achieved by optimizing the continuous flow process of up to 500 minutes. The main reaction product from this process was hydroquinone, of up to 60 percent with a number of the minor products of which not all could be identified. In order to utilize the characteristics of this reactor system, its design and reaction conditions such as applied potential, phenol concentration, co-solvent concentration and support electrolyte concentration were investigated to optimize the convection of phenol and the yield of hydroquinone.
- Full Text:
- Date Issued: 2010
- Authors: Pongoma, Basanda
- Date: 2010
- Subjects: Phenol , Hydroquinone
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10381 , http://hdl.handle.net/10948/1479 , Phenol , Hydroquinone
- Description: The electrochemical oxidation of phenol can be considered as an important process for either producing value added products such as hydroquinone and catechol or for the removal of the phenol from waste water streams to form carbon dioxide. This process had been extensively studied with the main focus on type of anode material used. Even though the anode material could be made from a range of materials, this study focused on using PbO2 as anode material that was made by using Pb-acid battery principles in designing a microporous electrode. In this study, the focus was on using lead dioxide as an anode material that was made by using the formation principles used in the manufacturing of Pb-acid batteries. This allowed for the construction of an electrochemical flow-through micro-porous reactor that contained PbO2 as the anode and Pb as the cathode, allowing for a solution containing phenol to flow through the cell continuously. By applying a suitable potential across the cell, the almost complete oxidation of phenol would occur to form benzoquinone, which was followed by the sequential reduction to other products such as hydroquinone and catechol. The system was shown to be made up of tightly packed micro-porous material that had a very high surface area-to-volume ratio. The study showed that between 80 to 90 percent successful conversion of a 50 mM solution of phenol could be achieved by optimizing the continuous flow process of up to 500 minutes. The main reaction product from this process was hydroquinone, of up to 60 percent with a number of the minor products of which not all could be identified. In order to utilize the characteristics of this reactor system, its design and reaction conditions such as applied potential, phenol concentration, co-solvent concentration and support electrolyte concentration were investigated to optimize the convection of phenol and the yield of hydroquinone.
- Full Text:
- Date Issued: 2010
The management of extralimital giraffe (Giraffa Camelopardalis) in the mosaic thicket of Southern Cape, South Africa
- Authors: Cornelius, Andri Judith
- Date: 2010
- Subjects: Giraffe -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape , Giraffe -- Ecology -- South Africa -- Eastern Cape , Animal behavior , Animal-plant relationships -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10749 , http://hdl.handle.net/10948/1345 , Giraffe -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape , Giraffe -- Ecology -- South Africa -- Eastern Cape , Animal behavior , Animal-plant relationships -- South Africa -- Eastern Cape
- Description: The giraffe at Nyaru were found to be browsers who made little use of graze during the study period. They utilized a diversity of 20 browse species. Two species, Acacia karroo and Acacia cyclops, formed the bulk of the giraffe diet throughout the year. A definite seasonal dietary shift was evident. A. karroo was favoured in summer and autumn and formed the main food species in spring, summer and autumn. A. cyclops was favoured throughout the study, but its contribution to the diet increased during winter when less A. karroo was consumed. This seasonal shift is related to the deciduous nature of Acacia karroo. Although a seasonal shift in species contribution to giraffe diet has been observed in many other giraffe feeding studies, no studies on giraffe feeding have been done in the Mosaic Thicket of the southern Cape. The ecological browsing capacity for giraffe in thicket was estimated to be between 0.020 BU/ha and 0.095 BU/ha. The browsing capacity for giraffe at Nyaru, based on the available phytomass 2–5 m above the ground, was estimated using those species that formed the bulk of the giraffe diet, and amounted to 0.063 BU/ha. A maximum of three giraffe could thus be stocked on the 157 ha of suitable giraffe habitat on Nyaru. This stocking rate recommendation lies within the range commonly recommended by local consultants for giraffe introductions into the southern Cape. Their recommendations are, however, not based on quantitative assessments such as performed in this study. The recommendation of this study should not be applied as a fixed ecological capacity for giraffe in thicket, but should be seen as a starting point in the adaptive management cycle. Ongoing monitoring of parameters, such as herbaceous composition and phytomass; as well as the condition of key browse species, is strongly advocated. A. karroo was browsed significantly more and carried significantly fewer pods per tree at a heavily used site compared to a lightly used site. Heavy browsing thus appears to affect the reproductive success of A. karroo significantly. Fewer pods are likely to lead to lower regeneration and thus reduced density of A. karroo. Whether A. karroo will maintain its dominance within the thicket vii community in the long run will be related to how individual plants survive and reproduce and if some can escape from herbivory. Fewer G. occidentalis were clumped with other species at the heavily used site compared to the lightly used site. This could possibly be attributed to the fact that intense browsing pressure at the heavily used site caused protective clumps to be eaten away, thus exposing G. occidentalis to higher ungulate browsing. Previous studies have found that nurse shrubs protect G. occidentalis against ungulate browsing. G. occidentalis was browsed significantly more at the heavily used site compared to the lightly used site. There was a general trend of fewer fruits at the heavily used site compared to the lightly used site, while fruits were absent on G. occidentalis growing alone at the heavily used site. This suggests a negative effect of heavy browsing on plant reproductive success and emphasizes the importance of nurse plants for the successful recruitment and hence long term prevalence of G. occidentalis in Mosaic Thicket.
- Full Text:
- Date Issued: 2010
- Authors: Cornelius, Andri Judith
- Date: 2010
- Subjects: Giraffe -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape , Giraffe -- Ecology -- South Africa -- Eastern Cape , Animal behavior , Animal-plant relationships -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10749 , http://hdl.handle.net/10948/1345 , Giraffe -- South Africa -- Eastern Cape , Giraffe -- Food -- South Africa -- Eastern Cape , Giraffe -- Ecology -- South Africa -- Eastern Cape , Animal behavior , Animal-plant relationships -- South Africa -- Eastern Cape
- Description: The giraffe at Nyaru were found to be browsers who made little use of graze during the study period. They utilized a diversity of 20 browse species. Two species, Acacia karroo and Acacia cyclops, formed the bulk of the giraffe diet throughout the year. A definite seasonal dietary shift was evident. A. karroo was favoured in summer and autumn and formed the main food species in spring, summer and autumn. A. cyclops was favoured throughout the study, but its contribution to the diet increased during winter when less A. karroo was consumed. This seasonal shift is related to the deciduous nature of Acacia karroo. Although a seasonal shift in species contribution to giraffe diet has been observed in many other giraffe feeding studies, no studies on giraffe feeding have been done in the Mosaic Thicket of the southern Cape. The ecological browsing capacity for giraffe in thicket was estimated to be between 0.020 BU/ha and 0.095 BU/ha. The browsing capacity for giraffe at Nyaru, based on the available phytomass 2–5 m above the ground, was estimated using those species that formed the bulk of the giraffe diet, and amounted to 0.063 BU/ha. A maximum of three giraffe could thus be stocked on the 157 ha of suitable giraffe habitat on Nyaru. This stocking rate recommendation lies within the range commonly recommended by local consultants for giraffe introductions into the southern Cape. Their recommendations are, however, not based on quantitative assessments such as performed in this study. The recommendation of this study should not be applied as a fixed ecological capacity for giraffe in thicket, but should be seen as a starting point in the adaptive management cycle. Ongoing monitoring of parameters, such as herbaceous composition and phytomass; as well as the condition of key browse species, is strongly advocated. A. karroo was browsed significantly more and carried significantly fewer pods per tree at a heavily used site compared to a lightly used site. Heavy browsing thus appears to affect the reproductive success of A. karroo significantly. Fewer pods are likely to lead to lower regeneration and thus reduced density of A. karroo. Whether A. karroo will maintain its dominance within the thicket vii community in the long run will be related to how individual plants survive and reproduce and if some can escape from herbivory. Fewer G. occidentalis were clumped with other species at the heavily used site compared to the lightly used site. This could possibly be attributed to the fact that intense browsing pressure at the heavily used site caused protective clumps to be eaten away, thus exposing G. occidentalis to higher ungulate browsing. Previous studies have found that nurse shrubs protect G. occidentalis against ungulate browsing. G. occidentalis was browsed significantly more at the heavily used site compared to the lightly used site. There was a general trend of fewer fruits at the heavily used site compared to the lightly used site, while fruits were absent on G. occidentalis growing alone at the heavily used site. This suggests a negative effect of heavy browsing on plant reproductive success and emphasizes the importance of nurse plants for the successful recruitment and hence long term prevalence of G. occidentalis in Mosaic Thicket.
- Full Text:
- Date Issued: 2010
The possibility of a flexible wireless 3-D measurement in the modern automobile production
- Authors: Frede, Stefan
- Date: 2010
- Subjects: Three-dimensional display systems , Automobile industry and trade , Automobile industry and trade -- South Africa -- Quality control
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9619 , http://hdl.handle.net/10948/1203 , Three-dimensional display systems , Automobile industry and trade , Automobile industry and trade -- South Africa -- Quality control
- Description: The quality control of geometrical coherences and relations in modern automobile production is done by different stationary and flexible measurement systems and strategies. Furthermore, there currently exists possibilities of inline measurements and offline measurements. This project presents the basic research concerning the possibility of a flexible wireless measurement system in modern automobile production, that is able to combine the advantages of both strategies. An investigation of existing measurement techniques was done in order to find a sensor technology, which enables the wireless measurement process. The research project introduces the current location systems and positioning systems. These techniques are compared by a value benefit analysis to expose a suited technology as basis for the measurement system. As result of the value benefit anlysis, the ultrasonic technique was selected for further investigations. The ultrasonic test setup is used to analyze the accuracy of modern sensors and to verify the possibility of a project related integration. The tests are done in different conditions, in order to compare the laboratory application and the industrial application. During the test measurements different physical influencing variables and disturbances occurred. From this research project, it can be concluded that the laboratory application of the system is possible. However, the industrial application is subject to restrictions.
- Full Text:
- Date Issued: 2010
- Authors: Frede, Stefan
- Date: 2010
- Subjects: Three-dimensional display systems , Automobile industry and trade , Automobile industry and trade -- South Africa -- Quality control
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9619 , http://hdl.handle.net/10948/1203 , Three-dimensional display systems , Automobile industry and trade , Automobile industry and trade -- South Africa -- Quality control
- Description: The quality control of geometrical coherences and relations in modern automobile production is done by different stationary and flexible measurement systems and strategies. Furthermore, there currently exists possibilities of inline measurements and offline measurements. This project presents the basic research concerning the possibility of a flexible wireless measurement system in modern automobile production, that is able to combine the advantages of both strategies. An investigation of existing measurement techniques was done in order to find a sensor technology, which enables the wireless measurement process. The research project introduces the current location systems and positioning systems. These techniques are compared by a value benefit analysis to expose a suited technology as basis for the measurement system. As result of the value benefit anlysis, the ultrasonic technique was selected for further investigations. The ultrasonic test setup is used to analyze the accuracy of modern sensors and to verify the possibility of a project related integration. The tests are done in different conditions, in order to compare the laboratory application and the industrial application. During the test measurements different physical influencing variables and disturbances occurred. From this research project, it can be concluded that the laboratory application of the system is possible. However, the industrial application is subject to restrictions.
- Full Text:
- Date Issued: 2010
Veldram performance testing of dorper rams in Namibia : performance testing, progency testing and factors influencing sale price of rams
- Grobler, Hermanus Johannes Fourie
- Authors: Grobler, Hermanus Johannes Fourie
- Date: 2010
- Subjects: Dorper sheep -- Breeding -- Namibia , Sheep -- Breeding -- Namibia , Dorper sheep , Sheep breeds
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10733 , http://hdl.handle.net/10948/1545 , Dorper sheep -- Breeding -- Namibia , Sheep -- Breeding -- Namibia , Dorper sheep , Sheep breeds
- Description: The study aims to determine the contribution made by available ram growth- and breed standard parameters on the sale price of auctioned rams in Namibia. These findings serve as an indication of the importance ram buyers place on individual parameters in selecting rams for breeding purposes. It furthermore tries to establish whether scientific measurement for the estimation of ram breeding values takes precedence over subjective appraisal. The analysis of the 100 day and 270 day growth performance of the progeny of selected Veldram tested rams were used to evaluate the accuracy of the estimation of ram breeding values and may serve to validate the proper execution of these Veldram tests.
- Full Text:
- Date Issued: 2010
- Authors: Grobler, Hermanus Johannes Fourie
- Date: 2010
- Subjects: Dorper sheep -- Breeding -- Namibia , Sheep -- Breeding -- Namibia , Dorper sheep , Sheep breeds
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10733 , http://hdl.handle.net/10948/1545 , Dorper sheep -- Breeding -- Namibia , Sheep -- Breeding -- Namibia , Dorper sheep , Sheep breeds
- Description: The study aims to determine the contribution made by available ram growth- and breed standard parameters on the sale price of auctioned rams in Namibia. These findings serve as an indication of the importance ram buyers place on individual parameters in selecting rams for breeding purposes. It furthermore tries to establish whether scientific measurement for the estimation of ram breeding values takes precedence over subjective appraisal. The analysis of the 100 day and 270 day growth performance of the progeny of selected Veldram tested rams were used to evaluate the accuracy of the estimation of ram breeding values and may serve to validate the proper execution of these Veldram tests.
- Full Text:
- Date Issued: 2010