Ultraprecision Diamond Turning of Monocrystalline Germanium
- Authors: Adeleke, Adeniyi Kehinde
- Date: 2021-04
- Subjects: Precision , Diamond Turning
- Language: English
- Type: Master's theses , Thesis
- Identifier: http://hdl.handle.net/10948/44453 , vital:37835
- Description: Infrared lens production demands a surface with a high degree of accuracy and integrity. Surface roughness is a critical index of the measure of any product’s surface integrity. As a result of this, ultra-high machining technology has enjoyed extensive application, due to the continuous request for components within the range of 1 – 10nm roughness value. This technology has brought about the increased productivity and manufacture of quality products with a top-notch surface finish. Brittle materials such as germanium are hard to machine through the conventional processes such as lapping and polishing. Hence, the ultra-precision machining technology based on single point diamond turning (SPDT), is now been applied to machine germanium in the ductile mode, where material chip removal occurs by plastic deformation instead of a brittle fracture. During machining, selecting the optimal cutting conditions which includes cutting parameters and tool geometry, will not only improve productivity but ensure the minimisation of operating cost. In this research work, SPDT operation was used to conduct two experiments on a (monocrystalline germanium) workpiece. The first experiment was carried out using a diamond tool with a 1.5 mm nose radius, while the second experiment employed the use of a tool having a nose radius of 1.0 mm. A combination of machining parameters for each of the experimental runs were derived from a Box-Behnken method of design and the surface roughness was measured at each interval for both experiments with the aid of a Taylor Hopson PGI Dimension XL profilometer. Acoustic emission (AE) was also used as a quality sensing and tool-monitoring technique, to acquire signals and give indications of the expected surface roughness. Predictive models based on response surface methodology (RSM) and artificial neural networks (ANN), were developed for determining surface roughness. Optimisation was performed using RSM to determine the optimal set of machining factors, which results in optimal condition of the output response. Further investigations on the acquired signals were carried out using signal-processing techniques. Time-domain and time-frequency domain features acquired from the AE signals, together with the process parameters, were employed as input variables in the neural network design, having shown a good association with the surface roughness. ix Conclusively, it can be observed that the predictive model results and the experimental roughness measurements are in good agreement with each other. For accuracy and cost of computation, the RSM and ANN developed models for single-crystal germanium are compared using mean absolute error (MAE). , Thesis (M.Eng) -- Faculty of Engineering, the built environment & Information Technology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Adeleke, Adeniyi Kehinde
- Date: 2021-04
- Subjects: Precision , Diamond Turning
- Language: English
- Type: Master's theses , Thesis
- Identifier: http://hdl.handle.net/10948/44453 , vital:37835
- Description: Infrared lens production demands a surface with a high degree of accuracy and integrity. Surface roughness is a critical index of the measure of any product’s surface integrity. As a result of this, ultra-high machining technology has enjoyed extensive application, due to the continuous request for components within the range of 1 – 10nm roughness value. This technology has brought about the increased productivity and manufacture of quality products with a top-notch surface finish. Brittle materials such as germanium are hard to machine through the conventional processes such as lapping and polishing. Hence, the ultra-precision machining technology based on single point diamond turning (SPDT), is now been applied to machine germanium in the ductile mode, where material chip removal occurs by plastic deformation instead of a brittle fracture. During machining, selecting the optimal cutting conditions which includes cutting parameters and tool geometry, will not only improve productivity but ensure the minimisation of operating cost. In this research work, SPDT operation was used to conduct two experiments on a (monocrystalline germanium) workpiece. The first experiment was carried out using a diamond tool with a 1.5 mm nose radius, while the second experiment employed the use of a tool having a nose radius of 1.0 mm. A combination of machining parameters for each of the experimental runs were derived from a Box-Behnken method of design and the surface roughness was measured at each interval for both experiments with the aid of a Taylor Hopson PGI Dimension XL profilometer. Acoustic emission (AE) was also used as a quality sensing and tool-monitoring technique, to acquire signals and give indications of the expected surface roughness. Predictive models based on response surface methodology (RSM) and artificial neural networks (ANN), were developed for determining surface roughness. Optimisation was performed using RSM to determine the optimal set of machining factors, which results in optimal condition of the output response. Further investigations on the acquired signals were carried out using signal-processing techniques. Time-domain and time-frequency domain features acquired from the AE signals, together with the process parameters, were employed as input variables in the neural network design, having shown a good association with the surface roughness. ix Conclusively, it can be observed that the predictive model results and the experimental roughness measurements are in good agreement with each other. For accuracy and cost of computation, the RSM and ANN developed models for single-crystal germanium are compared using mean absolute error (MAE). , Thesis (M.Eng) -- Faculty of Engineering, the built environment & Information Technology, 2021
- Full Text:
- Date Issued: 2021-04
Isolation, propagation and rapid molecular detection of the Kalahari truffle, a mycorrhizal fungus occurring in South Africa
- Authors: Adeleke, Rasheed Adegbola
- Date: 2007 , 2013-04-03
- Subjects: Truffles -- Kalahari Desert , Fungi -- Identification , Mycorrhizal fungi -- South Africa , Edible fungi -- South Africa , Mushroom culture -- South Africa , Fungi -- Cultures and culture media -- South Africa , Truffles -- South Africa , Truffles -- Lifecycles , Mycorrhizal fungi -- Lifecycles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3889 , http://hdl.handle.net/10962/d1002951 , Truffles -- Kalahari Desert , Fungi -- Identification , Mycorrhizal fungi -- South Africa , Edible fungi -- South Africa , Mushroom culture -- South Africa , Fungi -- Cultures and culture media -- South Africa , Truffles -- South Africa , Truffles -- Lifecycles , Mycorrhizal fungi -- Lifecycles
- Description: Terfezia pfeilii is an edible mycorrhizal fungus that thrives in the Kalahari Desert of southern Africa. It is best known by desert dwellers for its flavour and as a source of nutrition. Although the genus Terfezia is generally regarded as being an ectomycorrhizal mycobiont, the exact mycorrhizal type formed by T. pfeilli and its' associated host plants remains uncertain. Discovery of the host plants for T. pfeilii would first be required in order to further investigate the life cycle and cultivation of this truffle. This study focussed on the isolation of mycelia from the ascocarp, optimising the growth conditions of the mycelial cultures, rapid molecular identification of T. pfeilii, investigation of potential helper bacteria and mycorrhizal synthesis experiments. T. pfeilii ascocarps were harvested from the Spitskop Nature Reserve in Upington, South Africa. Ascocarps were successfully identified using both morphological and molecular methods. Despite the delayed growth mostly caused by contaminating microorganisms, the isolation of T. pfeilii mycelia culture was successful. Molecular techniques were used to confirm the identity of the pure culture. Further studies were conducted on ways to improve the growth conditions of the mycelial culture on Fontana medium. An optimum temperature of 32°C, the addition of Bovine Serum Albumin as a nitrogen source and a pH of 7.5 significantly improved the growth of T. pfeilii in vitro. A rapid PeR-based molecular method was developed to speed up the identification of T. pfeilii. Specific primers that can exclusively amplify the ITS region of T. pfeilii were designed and used to identify both the ascocarps and the mycelial culture. The specificity of these primers was confirmed by their inability to amplify DNA from the isolates of contamining fungi obtained during the isolation process. Molecular comparison was made to confirm the reclassification of South African samples of T. pfeilii as Kalaharituber pfeilii as proposed by Ferdman et al.,(2005). However, in this study, the name T. pfeilii has been retained. A total of 17 bacterial isolates were obtained from the fruiting bodies of T. pfeaii and these were tested for stimulation of mycelial growth in vitro, indole production and phosphate solubilising capabilities. Bacterial isolates that showed potential to be Mycorrhization Helper Bacteria (MHB) were identified as Paenibacillus sp., Bacillus sp. and Rhizobium tropici. Selected plant seedlings were inoculated with T. pfeilii cultures or ascocarp slurry in order to re-establish the mycorrhizal association. After 8 months, light microscopy observations revealed an endomycorrhizal type association between Cynodon dactylon and T. pfeilii. This was confirmed with molecular analysis using specific T. pfeilii ITS primers. After 15 months, molecular methods confirmed Acacia erioloba as another host plant. These results have provided essential information paving the way for further investigation into the life cycle and biology of the Kalahari truffle. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2007
- Authors: Adeleke, Rasheed Adegbola
- Date: 2007 , 2013-04-03
- Subjects: Truffles -- Kalahari Desert , Fungi -- Identification , Mycorrhizal fungi -- South Africa , Edible fungi -- South Africa , Mushroom culture -- South Africa , Fungi -- Cultures and culture media -- South Africa , Truffles -- South Africa , Truffles -- Lifecycles , Mycorrhizal fungi -- Lifecycles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3889 , http://hdl.handle.net/10962/d1002951 , Truffles -- Kalahari Desert , Fungi -- Identification , Mycorrhizal fungi -- South Africa , Edible fungi -- South Africa , Mushroom culture -- South Africa , Fungi -- Cultures and culture media -- South Africa , Truffles -- South Africa , Truffles -- Lifecycles , Mycorrhizal fungi -- Lifecycles
- Description: Terfezia pfeilii is an edible mycorrhizal fungus that thrives in the Kalahari Desert of southern Africa. It is best known by desert dwellers for its flavour and as a source of nutrition. Although the genus Terfezia is generally regarded as being an ectomycorrhizal mycobiont, the exact mycorrhizal type formed by T. pfeilli and its' associated host plants remains uncertain. Discovery of the host plants for T. pfeilii would first be required in order to further investigate the life cycle and cultivation of this truffle. This study focussed on the isolation of mycelia from the ascocarp, optimising the growth conditions of the mycelial cultures, rapid molecular identification of T. pfeilii, investigation of potential helper bacteria and mycorrhizal synthesis experiments. T. pfeilii ascocarps were harvested from the Spitskop Nature Reserve in Upington, South Africa. Ascocarps were successfully identified using both morphological and molecular methods. Despite the delayed growth mostly caused by contaminating microorganisms, the isolation of T. pfeilii mycelia culture was successful. Molecular techniques were used to confirm the identity of the pure culture. Further studies were conducted on ways to improve the growth conditions of the mycelial culture on Fontana medium. An optimum temperature of 32°C, the addition of Bovine Serum Albumin as a nitrogen source and a pH of 7.5 significantly improved the growth of T. pfeilii in vitro. A rapid PeR-based molecular method was developed to speed up the identification of T. pfeilii. Specific primers that can exclusively amplify the ITS region of T. pfeilii were designed and used to identify both the ascocarps and the mycelial culture. The specificity of these primers was confirmed by their inability to amplify DNA from the isolates of contamining fungi obtained during the isolation process. Molecular comparison was made to confirm the reclassification of South African samples of T. pfeilii as Kalaharituber pfeilii as proposed by Ferdman et al.,(2005). However, in this study, the name T. pfeilii has been retained. A total of 17 bacterial isolates were obtained from the fruiting bodies of T. pfeaii and these were tested for stimulation of mycelial growth in vitro, indole production and phosphate solubilising capabilities. Bacterial isolates that showed potential to be Mycorrhization Helper Bacteria (MHB) were identified as Paenibacillus sp., Bacillus sp. and Rhizobium tropici. Selected plant seedlings were inoculated with T. pfeilii cultures or ascocarp slurry in order to re-establish the mycorrhizal association. After 8 months, light microscopy observations revealed an endomycorrhizal type association between Cynodon dactylon and T. pfeilii. This was confirmed with molecular analysis using specific T. pfeilii ITS primers. After 15 months, molecular methods confirmed Acacia erioloba as another host plant. These results have provided essential information paving the way for further investigation into the life cycle and biology of the Kalahari truffle. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2007
The factors that contribute to students’ positive perceptions towards service quality in selected off-campus residences in Nelson Mandela Bay
- Authors: Adeleke, Thobile
- Date: 2021-04
- Subjects: SERVQUAL (Service quality framework) , Student housing -- Resident satisfaction -- South Africa , Consumer satisfaction -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/50922 , vital:43172
- Description: Post 1994 in South Africa there has been a notable increase in the number of students enrolled at different universities which offer student accommodation. Unfortunately, only 20% of the students can be accommodated in on-campus university accommodation, which results in most students seeking accommodation in off-campus student residences many of whom do not meet the quality requirements stipulated by the Department of Higher Education. This is what prompted this research study, whose aim was to investigate the perceptions of NMU students residing in off-campus residence, towards service quality. A literature review was conducted and focused on the service quality construct, delved into the definitions of services and quality and their benefits in all industries as well as within the student housing context. The different theoretical models used in the evaluation of service quality i.e., SERVQUAL, SERVPERF, the Gaps Model and Gronroos Model were discussed. A questionnaire based on the modified SERVQUAL tool was utilized in the evaluation of service quality levels in accredited NMU off-campus residences in Nelson Mandela Bay. Statistical evaluations were conducted on the five dimensions of SERVQUAL, namely, reliability; responsiveness; assurance; empathy and tangibles/physical attributes. The primary objective of this research was achieved, as the perceptions of students towards service quality in off-campus student accommodation were successfully measured using the SERVQUAL tool. Three service quality dimensions, namely, assurance, empathy and tangibles received positive assessments. On the other hand, the empirical research results clearly demonstrated two factors that scored low i.e., reliability and responsiveness, which reflects the respondents’ negative perceptions towards these two factors. Practical steps must be taken by off-campus residence management to ensure that the expectations versus perception service gap highlighted by the empirical findings of this study are addressed in order to keep their customers satisfied and remain competitive. Cronbach alpha coefficients above 0.80 were obtained for all the five variables, proving the SERVQUAL instrument’s internal consistency and reliability to be very good. , Thesis (MBA) -- Faculty of Business and Economic Science, Business Administration, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Adeleke, Thobile
- Date: 2021-04
- Subjects: SERVQUAL (Service quality framework) , Student housing -- Resident satisfaction -- South Africa , Consumer satisfaction -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/50922 , vital:43172
- Description: Post 1994 in South Africa there has been a notable increase in the number of students enrolled at different universities which offer student accommodation. Unfortunately, only 20% of the students can be accommodated in on-campus university accommodation, which results in most students seeking accommodation in off-campus student residences many of whom do not meet the quality requirements stipulated by the Department of Higher Education. This is what prompted this research study, whose aim was to investigate the perceptions of NMU students residing in off-campus residence, towards service quality. A literature review was conducted and focused on the service quality construct, delved into the definitions of services and quality and their benefits in all industries as well as within the student housing context. The different theoretical models used in the evaluation of service quality i.e., SERVQUAL, SERVPERF, the Gaps Model and Gronroos Model were discussed. A questionnaire based on the modified SERVQUAL tool was utilized in the evaluation of service quality levels in accredited NMU off-campus residences in Nelson Mandela Bay. Statistical evaluations were conducted on the five dimensions of SERVQUAL, namely, reliability; responsiveness; assurance; empathy and tangibles/physical attributes. The primary objective of this research was achieved, as the perceptions of students towards service quality in off-campus student accommodation were successfully measured using the SERVQUAL tool. Three service quality dimensions, namely, assurance, empathy and tangibles received positive assessments. On the other hand, the empirical research results clearly demonstrated two factors that scored low i.e., reliability and responsiveness, which reflects the respondents’ negative perceptions towards these two factors. Practical steps must be taken by off-campus residence management to ensure that the expectations versus perception service gap highlighted by the empirical findings of this study are addressed in order to keep their customers satisfied and remain competitive. Cronbach alpha coefficients above 0.80 were obtained for all the five variables, proving the SERVQUAL instrument’s internal consistency and reliability to be very good. , Thesis (MBA) -- Faculty of Business and Economic Science, Business Administration, 2021
- Full Text:
- Date Issued: 2021-04
Mxinwa MSc Cover & Abstract.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7873 , vital:55151
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- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7873 , vital:55151
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emerging-agribusiness-innovation-strategies-as-opportunities-for-agroentrepreneurs-in-kwazulu-natal.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7428 , vital:53968
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- Identifier: http://hdl.handle.net/11260/7428 , vital:53968
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- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7623 , vital:54740
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- Identifier: http://hdl.handle.net/11260/7623 , vital:54740
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Muballe PhD 2017.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7887 , vital:55155
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- Identifier: http://hdl.handle.net/11260/7887 , vital:55155
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- Identifier: http://hdl.handle.net/11260/6550 , vital:46488
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- Identifier: http://hdl.handle.net/11260/6550 , vital:46488
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Research Profile Dr Shakespeare .pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7123 , vital:52888
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- Identifier: http://hdl.handle.net/11260/7123 , vital:52888
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- Identifier: http://hdl.handle.net/11260/7679 , vital:54752
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- Identifier: http://hdl.handle.net/11260/7679 , vital:54752
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An-investigation-of-the-perception-of-office-management-and-technology-students-on-virtual-teaching-1528-2686-27-3-528.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7432 , vital:53967
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- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7432 , vital:53967
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Employee-motivation-in-crisis-situations-the-case-of-a-selected-organization-in-the-food-and-retail-1528-2686-27-2-491.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7399 , vital:53972
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- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7399 , vital:53972
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Functional-strategies-for-small-businesses-during-crisis-situations-1528-2686-27-3-527.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/8100 , vital:61390
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- Identifier: http://hdl.handle.net/11260/8100 , vital:61390
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an-agentic-view-of-the-determinants-of-successful-agribusinesses-at-a-rural-community-in-the-eastern-cape-province-of-so.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/8092 , vital:61385
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- Identifier: http://hdl.handle.net/11260/8092 , vital:61385
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5307-28134-1-PB.pdf
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- Identifier: http://hdl.handle.net/11260/8139 , vital:61380
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- Identifier: http://hdl.handle.net/11260/8139 , vital:61380
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- Identifier: http://hdl.handle.net/11260/8144 , vital:61379
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- Identifier: http://hdl.handle.net/11260/8144 , vital:61379
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5221-28013-1-PB.pdf
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- Identifier: http://hdl.handle.net/11260/8130 , vital:61376
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- Identifier: http://hdl.handle.net/11260/8130 , vital:61376
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s12906-021-03361-8.pdf
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- Identifier: http://hdl.handle.net/11260/7648 , vital:54759
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- Identifier: http://hdl.handle.net/11260/7648 , vital:54759
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5393-29472-1-PB.pdf
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- Identifier: http://hdl.handle.net/11260/8076 , vital:61382
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- Identifier: http://hdl.handle.net/11260/8076 , vital:61382
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Researcher Profile and List of Publications Tatira.pdf
- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7114 , vital:52890
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- Authors: Adelin Kantore
- Identifier: http://hdl.handle.net/11260/7114 , vital:52890
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