Adaptive Neuro-Fuzzy Inference System modelling of surface topology in ultra-high precision diamond turning of rapidly solidified aluminium grade (RSA 443)
- Authors: Zvikomborero, Hweju
- Date: 2020
- Subjects: Mechatronics Surface roughness -- Measurement
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49441 , vital:41721
- Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
- Full Text:
- Date Issued: 2020
- Authors: Zvikomborero, Hweju
- Date: 2020
- Subjects: Mechatronics Surface roughness -- Measurement
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49441 , vital:41721
- Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
- Full Text:
- Date Issued: 2020
Phytochemical Analysis and Biological potential of leaves and peels of three Eastern Cape Citrus Species
- Authors: Matuka, Thandiswa
- Date: 2019
- Subjects: Phytochemical -- Analysis Biology -- Leaves and peels Citrus species -- Eastern Cape -- South Africa
- Language: English
- Type: Thesis , Masters , M Sc
- Identifier: http://hdl.handle.net/11260/1362 , vital:32263
- Description: Citrus sinensis, Citrus reticulata and Citrus clementine are citrus species that belong to a large family Rutaceae. Citrus leaves and peels are often regarded as waste products. In view of the environment pollution impact, the search for end use of citrus waste products for economic value and medicinal purposes was sort after. The aim of this study was to investigate chemical composition of citrus waste products (leaves and peels) essential oils and determine biological active volatile compounds from Citrus sinensis, Citrus reticulata and Citrus clementine Leaves and peels of Citrus sinensis, Citrus reticulata and Citrus clementine collected twice from citrus farm were extracted for essential oils using hydrodistillation method and analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for plant samples collected in 2016 and, gas chromatography (GC) and gas chromatography-triple quadrupole-mass spectrometry (GC-MSMS) for plant samples collected in 2017. The oil yield for Citrus sinensis was 0.19 - 0.85 %v/w for fresh and dried leaf and peels for samples collected in 2016 and 0.26 – 0.87% v/w for those collected in 2017. Analysis of the essential oils analyses identified sabinene (20.4% GCMS, 22.6% GCMSMS), terpinen-4-ol (13.2% GCMS, 6.8% GCMSMS) and linalool (7.6% GCMS, 19.3% GCMSMS) as major compounds in fresh leaves essential oils while β-elemene (16.3% GCMS, 21.4% GCMSMS) and sabinene (10.7% GCMS, 20.8% GCMSMS) were major compounds characterized in dried leaves essential oils. Fresh and dried peels essential oils had limonene as the major constituent (49.6% GCMS, 87.1% GCMSMS) and (73.6% GCMS, 88.3% GCMSMS) respectively. Citrus reticulata essential oils percentage yield range between 0.44-0.80% v/w for fresh and dried leaf and peel oils. Analyses of the GCMS and GCMSMS chromatogram of the volatile oils analyses revealed linalool (33.4% GCMS, 19.6% GCMSMS), (+)-spathulenol (15.2% GCMS, 10.1% GCMSMS) and terpinene-4-ol (4.5% GCMS, 11.9% GCMSMS) as major compounds in fresh leaf essential oils while, sabinene (20.8% GCMS, 32.5% GCMSMS) and linalool (17.2% GCMS, 20.4% GCMSMS) were the major compounds found in dried leaf essential oils. Limonene (55.2%, 75.4% GCMS; 39.5%, 80.8% GCMSMS) was the major prominent compound identified in the C. reticulata peel essential oils in fresh and dried peels respectively, followed by linalool (12.8%, 2.9% GCMS; 48.4%, 7.4% GCMSMS). Percentage yields for the essential oils from C. clementine fresh and dried leaves and peels ranges from 0.40-0.62% v/w for. Fresh and dried leaves volatile oils had sabinene (22.7-27.1%) for GCMS and GCMSMS respectively), linalool (18.5- 20.9% GCMS and GCMSMS) and terpinene-4-ol (6.5- 11.8% GCMS and GCMSMS) as main compounds while fresh and dried peels oils were dominated by limonene (38.9- 86.5% GCMS and GCMSMS). Phytochemical screening experiment of the three citrus species leaves and peels aqueous extract reveal the prominent presence of flavonoids and phenolic compounds in high concentrations. C. reticulata and C. clementine peels and leaves volatile oils exhibited higher antioxidant activity as DPPH free radical scavengers and Ferric reducing power (FRAP) ability, when compared to C. sinensis essential oils which exhibited minimum antioxidant activity. Antioxidant activity of leaves and peels essential oils maybe due to the presence of oxygenated monoterpenes and high limonene content. C. sinensis peels oils showed non-toxic to extremely very low toxicity effect at highest dose 2000 mg/kg. C. reticulata and C. clementine peels oils showed toxicity effect in mice at high dose levels. It is suggested that citrus volatile oils could be safe to use at lower dose levels. Citrus species peels and leaves volatile compounds limonene linalool and sabinene exhibited antiinflammatory activity by significantly reducing rats paw oedema size induced by fresh egg albumin. The study suggests the use of Citrus waste products (leaves and peels) as natural antioxidants with antiinflammatory properties for medicinal value and volatile oils compounds for aroma in beverages and cosmetic industries.
- Full Text:
- Date Issued: 2019
- Authors: Matuka, Thandiswa
- Date: 2019
- Subjects: Phytochemical -- Analysis Biology -- Leaves and peels Citrus species -- Eastern Cape -- South Africa
- Language: English
- Type: Thesis , Masters , M Sc
- Identifier: http://hdl.handle.net/11260/1362 , vital:32263
- Description: Citrus sinensis, Citrus reticulata and Citrus clementine are citrus species that belong to a large family Rutaceae. Citrus leaves and peels are often regarded as waste products. In view of the environment pollution impact, the search for end use of citrus waste products for economic value and medicinal purposes was sort after. The aim of this study was to investigate chemical composition of citrus waste products (leaves and peels) essential oils and determine biological active volatile compounds from Citrus sinensis, Citrus reticulata and Citrus clementine Leaves and peels of Citrus sinensis, Citrus reticulata and Citrus clementine collected twice from citrus farm were extracted for essential oils using hydrodistillation method and analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) for plant samples collected in 2016 and, gas chromatography (GC) and gas chromatography-triple quadrupole-mass spectrometry (GC-MSMS) for plant samples collected in 2017. The oil yield for Citrus sinensis was 0.19 - 0.85 %v/w for fresh and dried leaf and peels for samples collected in 2016 and 0.26 – 0.87% v/w for those collected in 2017. Analysis of the essential oils analyses identified sabinene (20.4% GCMS, 22.6% GCMSMS), terpinen-4-ol (13.2% GCMS, 6.8% GCMSMS) and linalool (7.6% GCMS, 19.3% GCMSMS) as major compounds in fresh leaves essential oils while β-elemene (16.3% GCMS, 21.4% GCMSMS) and sabinene (10.7% GCMS, 20.8% GCMSMS) were major compounds characterized in dried leaves essential oils. Fresh and dried peels essential oils had limonene as the major constituent (49.6% GCMS, 87.1% GCMSMS) and (73.6% GCMS, 88.3% GCMSMS) respectively. Citrus reticulata essential oils percentage yield range between 0.44-0.80% v/w for fresh and dried leaf and peel oils. Analyses of the GCMS and GCMSMS chromatogram of the volatile oils analyses revealed linalool (33.4% GCMS, 19.6% GCMSMS), (+)-spathulenol (15.2% GCMS, 10.1% GCMSMS) and terpinene-4-ol (4.5% GCMS, 11.9% GCMSMS) as major compounds in fresh leaf essential oils while, sabinene (20.8% GCMS, 32.5% GCMSMS) and linalool (17.2% GCMS, 20.4% GCMSMS) were the major compounds found in dried leaf essential oils. Limonene (55.2%, 75.4% GCMS; 39.5%, 80.8% GCMSMS) was the major prominent compound identified in the C. reticulata peel essential oils in fresh and dried peels respectively, followed by linalool (12.8%, 2.9% GCMS; 48.4%, 7.4% GCMSMS). Percentage yields for the essential oils from C. clementine fresh and dried leaves and peels ranges from 0.40-0.62% v/w for. Fresh and dried leaves volatile oils had sabinene (22.7-27.1%) for GCMS and GCMSMS respectively), linalool (18.5- 20.9% GCMS and GCMSMS) and terpinene-4-ol (6.5- 11.8% GCMS and GCMSMS) as main compounds while fresh and dried peels oils were dominated by limonene (38.9- 86.5% GCMS and GCMSMS). Phytochemical screening experiment of the three citrus species leaves and peels aqueous extract reveal the prominent presence of flavonoids and phenolic compounds in high concentrations. C. reticulata and C. clementine peels and leaves volatile oils exhibited higher antioxidant activity as DPPH free radical scavengers and Ferric reducing power (FRAP) ability, when compared to C. sinensis essential oils which exhibited minimum antioxidant activity. Antioxidant activity of leaves and peels essential oils maybe due to the presence of oxygenated monoterpenes and high limonene content. C. sinensis peels oils showed non-toxic to extremely very low toxicity effect at highest dose 2000 mg/kg. C. reticulata and C. clementine peels oils showed toxicity effect in mice at high dose levels. It is suggested that citrus volatile oils could be safe to use at lower dose levels. Citrus species peels and leaves volatile compounds limonene linalool and sabinene exhibited antiinflammatory activity by significantly reducing rats paw oedema size induced by fresh egg albumin. The study suggests the use of Citrus waste products (leaves and peels) as natural antioxidants with antiinflammatory properties for medicinal value and volatile oils compounds for aroma in beverages and cosmetic industries.
- Full Text:
- Date Issued: 2019
'n Eenvormige dissiplinestelsel vir skole in die Bitou 10-streek
- Authors: Freislich, Maria Francina
- Date: 2010
- Subjects: School discipline -- South Africa , School boards -- South Africa
- Language: Afrikaans
- Type: Thesis , Masters , MEd
- Identifier: vital:9506 , http://hdl.handle.net/10948/1236 , School discipline -- South Africa , School boards -- South Africa
- Description: Discipline in the government schools in South Africa has deteriorated during the past fifteen years. There are many different reasons for that. The aim of this study was to develop a uniform programme of discipline which can be used for application in all ten schools in the Bitou area. To reach this aim, the following procedures were followed: • A study has been done regarding the supporting role of the Bitou 10 foundation in the designing and management of a uniform discipline program. • A summary of the disciplinary problems in government schools has been given with possible reasons why discipline has deteriorated. • A study has also been made of various programs of discipline which have been used in various countries in the past. Certain aspects of those programmes have been used in this study to compile an effective programme of discipline for all the schools in the Bitou area. • Criteria for a positive discipline program have been put together. This study has been done in the Plettenberg Bay area. This area has ten schools which include primary- and high schools, single medium- and double medium schools, multi-cultural and mono-cultural schools and also some schools which have hostels. This study showed that not all schools in the Bitou area follow the same disciplinary programme. This study also makes recommendations on the possible implementing of such a uniform system of discipline. This study does not only show what the role is of the principal and teachers responsible for discipline, but also indicates the role and task of the parents and the community. Research on the application of discipline can never end because new ideas and methods will always be found to create an ideal programme in order to make the process more effective.
- Full Text:
- Date Issued: 2010
- Authors: Freislich, Maria Francina
- Date: 2010
- Subjects: School discipline -- South Africa , School boards -- South Africa
- Language: Afrikaans
- Type: Thesis , Masters , MEd
- Identifier: vital:9506 , http://hdl.handle.net/10948/1236 , School discipline -- South Africa , School boards -- South Africa
- Description: Discipline in the government schools in South Africa has deteriorated during the past fifteen years. There are many different reasons for that. The aim of this study was to develop a uniform programme of discipline which can be used for application in all ten schools in the Bitou area. To reach this aim, the following procedures were followed: • A study has been done regarding the supporting role of the Bitou 10 foundation in the designing and management of a uniform discipline program. • A summary of the disciplinary problems in government schools has been given with possible reasons why discipline has deteriorated. • A study has also been made of various programs of discipline which have been used in various countries in the past. Certain aspects of those programmes have been used in this study to compile an effective programme of discipline for all the schools in the Bitou area. • Criteria for a positive discipline program have been put together. This study has been done in the Plettenberg Bay area. This area has ten schools which include primary- and high schools, single medium- and double medium schools, multi-cultural and mono-cultural schools and also some schools which have hostels. This study showed that not all schools in the Bitou area follow the same disciplinary programme. This study also makes recommendations on the possible implementing of such a uniform system of discipline. This study does not only show what the role is of the principal and teachers responsible for discipline, but also indicates the role and task of the parents and the community. Research on the application of discipline can never end because new ideas and methods will always be found to create an ideal programme in order to make the process more effective.
- Full Text:
- Date Issued: 2010
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