The use of image processing to determine cell defects in polycrystalline solar modules
- Authors: Banda, Peter
- Date: 2019
- Subjects: Polycrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36573 , vital:33996
- Description: This research aims to use image processingtodetermine cell defects in polycrystalline solar modules. Image processing is a process of enhancing images for differentapplications. One domain that seems to not yet utilise the use of image processing, is photovoltaics. An increased use of fossil fuels is damaging the earth and a call to protect the earth has resulted in the emergence of pollutant-free technologies such as polycrystalline photovoltaic (PV) cells, which are connected to make up solar modules. However, defects often affect the performance of PV cells and consequently solar modules. Electroluminescence (EL) images are used to examine polycrystalline solar (PV) modules to determine if the modules are defective. The main research question that this research addressed is“How can an image processing technique be used to effectively identify defective polycrystalline PV cells from EL images of such cells?“. The experimental research methodology was used to address the main research question. The initial investigation into the problem revealed that certain sectors within industry, as well as the Physics Department at Nelson Mandela University(NMU), do not currently utiliseimage processing when examining EL images of solar modules. The current process is a tedious, manual process whereby solar modules are manually inspected. An analysis of the current processes enabled the identification of ways in which to automatically examine EL images of solar modules. An analysis of literatureprovided a better understanding of the different techniques that are used to examine solar modules, and it was identified how image processing can be applied to EL images. Further analysis of literatureprovided a better understanding of image processing and how image classification experiments using Deep Learning (DL) as an image processing technique can be used to address the main research question. The outcome of the experiments conducted in this research weredifferentadaptive models(LeNet, MobileNet, Xception)that can classify EL images of PV cellsaccording to known standardsused by the Physics Department at NMU. The known standards yielded four classes; normal, uncritical, critical and very critical, which were used for the classification of EL images of PV cells. The adaptive models were evaluated to obtain the precision, recall and F1–scoreof the models.The precession, recall, and F1–score were required to determine how effective the models were in identifying defective PV cells from EL images.The results indicated that an image processing technique canbe used to identify defective polycrystalline PV cells from EL images of such cells. However, further research needs to be conducted to improve the effectiveness of the adaptive models.
- Full Text:
- Date Issued: 2019
- Authors: Banda, Peter
- Date: 2019
- Subjects: Polycrystals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36573 , vital:33996
- Description: This research aims to use image processingtodetermine cell defects in polycrystalline solar modules. Image processing is a process of enhancing images for differentapplications. One domain that seems to not yet utilise the use of image processing, is photovoltaics. An increased use of fossil fuels is damaging the earth and a call to protect the earth has resulted in the emergence of pollutant-free technologies such as polycrystalline photovoltaic (PV) cells, which are connected to make up solar modules. However, defects often affect the performance of PV cells and consequently solar modules. Electroluminescence (EL) images are used to examine polycrystalline solar (PV) modules to determine if the modules are defective. The main research question that this research addressed is“How can an image processing technique be used to effectively identify defective polycrystalline PV cells from EL images of such cells?“. The experimental research methodology was used to address the main research question. The initial investigation into the problem revealed that certain sectors within industry, as well as the Physics Department at Nelson Mandela University(NMU), do not currently utiliseimage processing when examining EL images of solar modules. The current process is a tedious, manual process whereby solar modules are manually inspected. An analysis of the current processes enabled the identification of ways in which to automatically examine EL images of solar modules. An analysis of literatureprovided a better understanding of the different techniques that are used to examine solar modules, and it was identified how image processing can be applied to EL images. Further analysis of literatureprovided a better understanding of image processing and how image classification experiments using Deep Learning (DL) as an image processing technique can be used to address the main research question. The outcome of the experiments conducted in this research weredifferentadaptive models(LeNet, MobileNet, Xception)that can classify EL images of PV cellsaccording to known standardsused by the Physics Department at NMU. The known standards yielded four classes; normal, uncritical, critical and very critical, which were used for the classification of EL images of PV cells. The adaptive models were evaluated to obtain the precision, recall and F1–scoreof the models.The precession, recall, and F1–score were required to determine how effective the models were in identifying defective PV cells from EL images.The results indicated that an image processing technique canbe used to identify defective polycrystalline PV cells from EL images of such cells. However, further research needs to be conducted to improve the effectiveness of the adaptive models.
- Full Text:
- Date Issued: 2019
Single tree water use and water-use efficiencies of selected indigenous and introduced forest species in the southern Cape region of South Africa
- Authors: Mapeto, Tatenda
- Date: 2015
- Subjects: Irrigation efficiency -- South Africa -- Western Cape Pinus radiata -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11493 , vital:26932
- Description: In South Africa, the limited extent of indigenous forests accelerated the development of fast-growing introduced species plantations, on which the country is now heavily reliant for its fibre and timber products. However, the plantation forestry industry is challenged with limited freshwater resources, the need for sustainable management of introduced tree species in commercial forest production systems, and a diversity of plant ecological production factors such as soils that have to be manipulated for the purposes of increasing production capacities. Additionally, plantations are established in the limited high rainfall regions of the country and the industry’s water use has been regulated since 1972. Conversely, natural forests also provide valuable goods, however, their slow growth rates have restricted their development as commercial tree production systems. In this regard the forestry industry is continuously seeking to provide for the country’s timber and fibre needs while ensuring the provision of other ecosystem services from tree production systems. Recent developments in the forestry industry have therefore been focused on water use efficiency in current and alternative tree production systems. There is also widespread unsubstantiated belief that indigenous tree species are efficient users of water. Against this background this study sought to explore the single tree water use and water use efficiencies of introduced commercial plantation species (Pinus radiata) and that of important indigenous species (Ilex mitis, Ocotea bullata and Podocarpus latifolius) for timber and fibre production in the southern Cape region of South Africa. Single tree water use measurements were carried out for a year using the heat pulse velocity method. Growth measurements for utilisable stem wood were done on a quarterly basis for the specimen trees and growth increments over the year were determined. Single tree water use efficiency was a calculated as a function of grams of stem wood gained per litre of water transpired. Measurements of daily weather conditions and soil water content were concurrently taken during the year. The relationships between the variables that express daily climatic conditions, soil water content and daily volumes of transpired water were explored. Empirical models for the prediction of daily transpiration as a function of climate and soil water content were then developed using multiple linear regression analysis. Pinus radiata trees exhibited higher totals of volumetric transpiration than the indigenous species. The water use patterns of Pinus radiata showed higher peaks of maximum and minimum daily and seasonal water use while the indigenous species showed temperate patterns of water use throughout the year. Podocarpus latifolius attained the lowest water use efficiency in the year (0.49g/L) while Pinus radiata, Ocotea bullata and Ilex mitis had comparable water use efficiency values ranging between 1g/L to 2.50g/L. Significant positive correlations existed between climatic variables and daily sapflow volumes of the tree specimens. Daily total solar radiation showed the highest positive correlation with daily transpiration and the average value of the correlation coefficient for solar radiation and water use for all tree species was 0.70 (p < 0.001). Empirical models for predicting daily water use integrated the variables expressing plant available moisture and energy. The study enhances our understanding of single tree water use, water use efficiency, the drivers of transpiration and the applicability of such studies in developing rapid estimation techniques for water use in current and alternative South African tree production systems.
- Full Text:
- Date Issued: 2015
- Authors: Mapeto, Tatenda
- Date: 2015
- Subjects: Irrigation efficiency -- South Africa -- Western Cape Pinus radiata -- South Africa -- Western Cape
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/11493 , vital:26932
- Description: In South Africa, the limited extent of indigenous forests accelerated the development of fast-growing introduced species plantations, on which the country is now heavily reliant for its fibre and timber products. However, the plantation forestry industry is challenged with limited freshwater resources, the need for sustainable management of introduced tree species in commercial forest production systems, and a diversity of plant ecological production factors such as soils that have to be manipulated for the purposes of increasing production capacities. Additionally, plantations are established in the limited high rainfall regions of the country and the industry’s water use has been regulated since 1972. Conversely, natural forests also provide valuable goods, however, their slow growth rates have restricted their development as commercial tree production systems. In this regard the forestry industry is continuously seeking to provide for the country’s timber and fibre needs while ensuring the provision of other ecosystem services from tree production systems. Recent developments in the forestry industry have therefore been focused on water use efficiency in current and alternative tree production systems. There is also widespread unsubstantiated belief that indigenous tree species are efficient users of water. Against this background this study sought to explore the single tree water use and water use efficiencies of introduced commercial plantation species (Pinus radiata) and that of important indigenous species (Ilex mitis, Ocotea bullata and Podocarpus latifolius) for timber and fibre production in the southern Cape region of South Africa. Single tree water use measurements were carried out for a year using the heat pulse velocity method. Growth measurements for utilisable stem wood were done on a quarterly basis for the specimen trees and growth increments over the year were determined. Single tree water use efficiency was a calculated as a function of grams of stem wood gained per litre of water transpired. Measurements of daily weather conditions and soil water content were concurrently taken during the year. The relationships between the variables that express daily climatic conditions, soil water content and daily volumes of transpired water were explored. Empirical models for the prediction of daily transpiration as a function of climate and soil water content were then developed using multiple linear regression analysis. Pinus radiata trees exhibited higher totals of volumetric transpiration than the indigenous species. The water use patterns of Pinus radiata showed higher peaks of maximum and minimum daily and seasonal water use while the indigenous species showed temperate patterns of water use throughout the year. Podocarpus latifolius attained the lowest water use efficiency in the year (0.49g/L) while Pinus radiata, Ocotea bullata and Ilex mitis had comparable water use efficiency values ranging between 1g/L to 2.50g/L. Significant positive correlations existed between climatic variables and daily sapflow volumes of the tree specimens. Daily total solar radiation showed the highest positive correlation with daily transpiration and the average value of the correlation coefficient for solar radiation and water use for all tree species was 0.70 (p < 0.001). Empirical models for predicting daily water use integrated the variables expressing plant available moisture and energy. The study enhances our understanding of single tree water use, water use efficiency, the drivers of transpiration and the applicability of such studies in developing rapid estimation techniques for water use in current and alternative South African tree production systems.
- Full Text:
- Date Issued: 2015
Diversity management practices at Lovedale College
- Authors: Chola, Zolani
- Date: 2014
- Subjects: Diversity in the workplace -- South Africa -- King William's Town , Public universities and colleges -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9392 , http://hdl.handle.net/10948/d1021163
- Description: The global working environment has altered dramatically over the last decade and in particular, the workforce has begun to consist of many diverse individuals. The world has become a global marketplace, with boundaries between countries becoming increasingly vague and permeable. Advances in technology and the advent of a global economy have brought people from different countries closer together. Globalisation has precipitated many challenges in modern organisations, and one of these challenges is workforce diversity. Workforces in organisations differ in terms of gender, age, race, ethnicity and sexual orientation. Globally, countries are faced with the spiralling challenge of skills shortages and there is an expanding competition for skilled workers, specifically for those who possess scarce skills. This leads to an expatriation of skills, creating a natural increase in workforce diversity that expands beyond local ethnicity and language. This affects all organisations, including academic institutions such as universities, universities of technology and public further education and training colleges. Given this challenge organisations, educational institutions and other entities are investigating ways to better deal or serve their constituents. Lovedale PFET College is a public further education and training college that provides skills to young South Africans, specifically vocational related skills. The main research problem of this study was to identify the recommended diversity management best practices that characterise effective organisations and determine the extent to which these practices are applied at Lovedale PFET College. In order to address the problem, a theoretical study was conducted which focused on identifying the recommended diversity management best practices. In addition, interviews were conducted with managers at Lovedale College to gain an understanding of their perspective on diversity management. Based on the combined main points gleaned from theory and the interviews, a questionnaire was developed and administered to both academic and support staff at Lovedale PFET College to obtain their perceptions of the diversity practices and outcomes at the college. The results of the survey revealed that Lovedale PFET College could improve on the implementation of best practices in diversity management. Specifically, attention could be given to diversity education and training, and diversity management policies and procedures.
- Full Text:
- Date Issued: 2014
- Authors: Chola, Zolani
- Date: 2014
- Subjects: Diversity in the workplace -- South Africa -- King William's Town , Public universities and colleges -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9392 , http://hdl.handle.net/10948/d1021163
- Description: The global working environment has altered dramatically over the last decade and in particular, the workforce has begun to consist of many diverse individuals. The world has become a global marketplace, with boundaries between countries becoming increasingly vague and permeable. Advances in technology and the advent of a global economy have brought people from different countries closer together. Globalisation has precipitated many challenges in modern organisations, and one of these challenges is workforce diversity. Workforces in organisations differ in terms of gender, age, race, ethnicity and sexual orientation. Globally, countries are faced with the spiralling challenge of skills shortages and there is an expanding competition for skilled workers, specifically for those who possess scarce skills. This leads to an expatriation of skills, creating a natural increase in workforce diversity that expands beyond local ethnicity and language. This affects all organisations, including academic institutions such as universities, universities of technology and public further education and training colleges. Given this challenge organisations, educational institutions and other entities are investigating ways to better deal or serve their constituents. Lovedale PFET College is a public further education and training college that provides skills to young South Africans, specifically vocational related skills. The main research problem of this study was to identify the recommended diversity management best practices that characterise effective organisations and determine the extent to which these practices are applied at Lovedale PFET College. In order to address the problem, a theoretical study was conducted which focused on identifying the recommended diversity management best practices. In addition, interviews were conducted with managers at Lovedale College to gain an understanding of their perspective on diversity management. Based on the combined main points gleaned from theory and the interviews, a questionnaire was developed and administered to both academic and support staff at Lovedale PFET College to obtain their perceptions of the diversity practices and outcomes at the college. The results of the survey revealed that Lovedale PFET College could improve on the implementation of best practices in diversity management. Specifically, attention could be given to diversity education and training, and diversity management policies and procedures.
- Full Text:
- Date Issued: 2014
Retention strategies for knowledge workers at a consulting engineering firm
- Authors: Ketye, Lungelo
- Date: 2013
- Subjects: Employee retention , Employee motivation , Job satisfaction
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6247 , vital:21059
- Description: The Consulting Engineering industry plays a very critical role in the construction industry. Its primary role is to plan and design projects before they go on to the construction phase. During the construction phase of a project, consulting engineers are responsible for supervising the works and ensuring that construction is done according to design specifications. The selected company, where this study was conducted, provides civil engineering consulting services. The main purpose of the research was to identify retention strategies that could be used by the company in order to reduce staff turnover. To achieve this objective, the researcher completed a literature study. The literature study revealed the characteristics of knowledge workers, and what makes knowledge workers wish to extend their stay with an organisation. The study examined variables that lead to staff turnover i.e. leadership and communication, organizational culture, performance management and job satisfaction. The empirical study was conducted at LK Consulting Engineers. A survey with a questionnaire was administered to all engineering practitioners who were registered with the Engineering Council of South Africa. Interviews were also conducted with three managers. The study demonstrated that leadership and communication, organisational culture, performance management and job satisfaction are important variables leading to retention of knowledge workers. The study also demonstrated that training and financial remuneration is not enough to retain knowledge workers, employees should feel valued and provided with the opportunities to make meaningful contributions to the organisation.
- Full Text:
- Date Issued: 2013
- Authors: Ketye, Lungelo
- Date: 2013
- Subjects: Employee retention , Employee motivation , Job satisfaction
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/6247 , vital:21059
- Description: The Consulting Engineering industry plays a very critical role in the construction industry. Its primary role is to plan and design projects before they go on to the construction phase. During the construction phase of a project, consulting engineers are responsible for supervising the works and ensuring that construction is done according to design specifications. The selected company, where this study was conducted, provides civil engineering consulting services. The main purpose of the research was to identify retention strategies that could be used by the company in order to reduce staff turnover. To achieve this objective, the researcher completed a literature study. The literature study revealed the characteristics of knowledge workers, and what makes knowledge workers wish to extend their stay with an organisation. The study examined variables that lead to staff turnover i.e. leadership and communication, organizational culture, performance management and job satisfaction. The empirical study was conducted at LK Consulting Engineers. A survey with a questionnaire was administered to all engineering practitioners who were registered with the Engineering Council of South Africa. Interviews were also conducted with three managers. The study demonstrated that leadership and communication, organisational culture, performance management and job satisfaction are important variables leading to retention of knowledge workers. The study also demonstrated that training and financial remuneration is not enough to retain knowledge workers, employees should feel valued and provided with the opportunities to make meaningful contributions to the organisation.
- Full Text:
- Date Issued: 2013
Improving certain high performance properties of natural fibres
- Authors: Chapple, Stephen Anthony
- Date: 2007
- Subjects: Textile chemistry , Fireproofing of fabrics
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10451 , http://hdl.handle.net/10948/815 , Textile chemistry , Fireproofing of fabrics
- Description: Cotton possesses many characteristics that make it desirable to the consumer, and this has resulted in its usage in a broad range of products. Cotton, however, is a flammable material that is easily ignited and rapidly consumed. The flame retardant treatment of cotton is, therefore, an important textile process that has received wide attention over many years. There are a number of commercial flame retardant treatments available for cotton, the most common being phosphate-based. These treatments, however, often have drawbacks or have a negative impact on the desirable properties of the fibre and the challenge still exists for designing better flame retardant products and systems that are durable and have limited impact on fibre properties. The study considers the application of the sol-gel as a coating on fabric that was pre-treated with a phosphate-based flame retardant or as a means for applying a phosphate-based flame retardant. Both treatment methods were found to be suitable for imparting flame resistance to the fabric. The effect of various phosphate-based flame retardants on flammability and fabric properties such as colour, handle and strength was investigated and it was shown that a diammonium phosphate and urea combination gave the best flame resistance. In this regard, a flame resistance was achieved with a lower amount of phosphorous than was used in similar conventional treatments. The durability of the coating to rinsing with water and soaping with a detergent was also investigated. It was found that the flame resistance was lost after rinsing or soaping but the prevention of afterglow combustion was retained. It was shown that the preparatory treatment of the fabric influenced the sol-gel coating process and the flammability of the fabric. Mercerisation and bleaching of the fabric increased the “wet pick-up” during the coating process and improved the flame resistance. The influence of various factors was also investigated in further detail. The ratio of the sol-gel components, the delay after coating prior to drying (hang time) and the curing time were investigated using an experimental design. The curing time and the ratio of components in the sol-gel were shown to have the greatest influence on fabric properties and fabric flammability. It was shown that there is a trade-off between the desired high level of fabric flame resistance and preserving the inherent properties of the fabric such as colour, handle and strength.
- Full Text:
- Date Issued: 2007
- Authors: Chapple, Stephen Anthony
- Date: 2007
- Subjects: Textile chemistry , Fireproofing of fabrics
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10451 , http://hdl.handle.net/10948/815 , Textile chemistry , Fireproofing of fabrics
- Description: Cotton possesses many characteristics that make it desirable to the consumer, and this has resulted in its usage in a broad range of products. Cotton, however, is a flammable material that is easily ignited and rapidly consumed. The flame retardant treatment of cotton is, therefore, an important textile process that has received wide attention over many years. There are a number of commercial flame retardant treatments available for cotton, the most common being phosphate-based. These treatments, however, often have drawbacks or have a negative impact on the desirable properties of the fibre and the challenge still exists for designing better flame retardant products and systems that are durable and have limited impact on fibre properties. The study considers the application of the sol-gel as a coating on fabric that was pre-treated with a phosphate-based flame retardant or as a means for applying a phosphate-based flame retardant. Both treatment methods were found to be suitable for imparting flame resistance to the fabric. The effect of various phosphate-based flame retardants on flammability and fabric properties such as colour, handle and strength was investigated and it was shown that a diammonium phosphate and urea combination gave the best flame resistance. In this regard, a flame resistance was achieved with a lower amount of phosphorous than was used in similar conventional treatments. The durability of the coating to rinsing with water and soaping with a detergent was also investigated. It was found that the flame resistance was lost after rinsing or soaping but the prevention of afterglow combustion was retained. It was shown that the preparatory treatment of the fabric influenced the sol-gel coating process and the flammability of the fabric. Mercerisation and bleaching of the fabric increased the “wet pick-up” during the coating process and improved the flame resistance. The influence of various factors was also investigated in further detail. The ratio of the sol-gel components, the delay after coating prior to drying (hang time) and the curing time were investigated using an experimental design. The curing time and the ratio of components in the sol-gel were shown to have the greatest influence on fabric properties and fabric flammability. It was shown that there is a trade-off between the desired high level of fabric flame resistance and preserving the inherent properties of the fabric such as colour, handle and strength.
- Full Text:
- Date Issued: 2007
The identification of a model to promote intrapreneurship in an automotive component company
- Authors: Du Preez, Catherine Amanda
- Date: 2005
- Subjects: Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8549 , http://hdl.handle.net/10948/423 , Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Description: South African organisations are facing a new era of intense global competition. The modern business world is characterised by change and this change presents both challenges and opportunities. As a result, organisations have to become more responsive to change by continuous, rapid and cost-effective innovation through integrating the strengths of the entrepreneurial small firm, such as creativity, flexibility and innovativeness, with the market power and resources of the large firm. Due to the dynamic nature of the automotive industry, it is vital that South African organisations and management identify creativity and innovation as the main sources of sustainable competitive advantage. Sustained competitive advantage is derived from consistently satisfying customers’ wants and needs through innovation. An intrapreneurial philosophy is of key importance to an organisation’s corporate strategy, ensuring that entrepreneurial values are incorporated into the culture of the organisation. This study took place within an automotive component company operating in the Eastern Cape. Based on the theoretical findings of the literature study a questionnaire was developed and distributed to all employees of the company. The objective of the questionnaire was to measure the prevalence of intrapreneurship within the company and based on the findings of the literature study, recommendations on the structure, systems, culture and management styles of the organisation were made. Finally, a model was developed that identifies the importance of innovation, customer-solution centeredness and being market driven as core strategic values.
- Full Text:
- Date Issued: 2005
- Authors: Du Preez, Catherine Amanda
- Date: 2005
- Subjects: Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8549 , http://hdl.handle.net/10948/423 , Entrepreneurship , Automobile industry and trade -- South Africa , Organizational change
- Description: South African organisations are facing a new era of intense global competition. The modern business world is characterised by change and this change presents both challenges and opportunities. As a result, organisations have to become more responsive to change by continuous, rapid and cost-effective innovation through integrating the strengths of the entrepreneurial small firm, such as creativity, flexibility and innovativeness, with the market power and resources of the large firm. Due to the dynamic nature of the automotive industry, it is vital that South African organisations and management identify creativity and innovation as the main sources of sustainable competitive advantage. Sustained competitive advantage is derived from consistently satisfying customers’ wants and needs through innovation. An intrapreneurial philosophy is of key importance to an organisation’s corporate strategy, ensuring that entrepreneurial values are incorporated into the culture of the organisation. This study took place within an automotive component company operating in the Eastern Cape. Based on the theoretical findings of the literature study a questionnaire was developed and distributed to all employees of the company. The objective of the questionnaire was to measure the prevalence of intrapreneurship within the company and based on the findings of the literature study, recommendations on the structure, systems, culture and management styles of the organisation were made. Finally, a model was developed that identifies the importance of innovation, customer-solution centeredness and being market driven as core strategic values.
- Full Text:
- Date Issued: 2005
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