Development of spunlaced nonwoven filters from PAN, PPS and PI fibres for industrial use
- Authors: Maduna, Lebo
- Date: 2019
- Subjects: Textile fibers -- Mechanical properties , Nonwoven fabrics --Technological innovations Textile fibers, Synthetic -- Mechanical properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32610 , vital:32266
- Description: The aim of this work was to produce filter fabrics suitable for high temperature and other conditions encountered in coal power plants using the spunlacing manufacturing technique. Polyacrylonitrile (PAN), polyphenylene sulfide (PPS) and polyimide (PI) fibres being combined suitable for this purpose, each at three aerial density of (440, 500 and 560 g/m2) and each at three water jet pressures of (60, 80 and 90 bars) were produced. The effect of changing these on the fabric air permeability, tensile strength and filtration properties were investigated and optimized. For this purpose, the Box-Behnken experimental design (BBD) was considered the best and therefore used. The PPS/PI fabrics were found to consistently have the highest air permeability, tensile strength and filtration performance, followed by the PPS fabrics and the PAN fabrics. As could be expected, an increase in area weight and water jet pressure generally resulted in a decrease in air permeability irrespective of the fabric types, this being due to the increased number of fibres and therefore greater fibre surface area and entanglement respectively. For fabric tensile strength, the effects of varying fabric area weight and water jet pressure were not so straight forward. For cross direction (CD) an increase in water jet pressure resulted in an increase tensile strength whereas in the machine direction (MD) there was a decrease when the water jet pressure was increased. The filtration efficiency and dust holding capacity of the fabrics were found to be around 96% and 211g/m2, respectively, with the exception of the PPS (500 g/m2 80 bar) fabrics. Increasing the amount of dust being fed to the fabric during each loading cycle, it caused an increase in pressure drop, as the fabrics became increasingly clogged forming a cake layer.
- Full Text:
- Date Issued: 2019
- Authors: Maduna, Lebo
- Date: 2019
- Subjects: Textile fibers -- Mechanical properties , Nonwoven fabrics --Technological innovations Textile fibers, Synthetic -- Mechanical properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32610 , vital:32266
- Description: The aim of this work was to produce filter fabrics suitable for high temperature and other conditions encountered in coal power plants using the spunlacing manufacturing technique. Polyacrylonitrile (PAN), polyphenylene sulfide (PPS) and polyimide (PI) fibres being combined suitable for this purpose, each at three aerial density of (440, 500 and 560 g/m2) and each at three water jet pressures of (60, 80 and 90 bars) were produced. The effect of changing these on the fabric air permeability, tensile strength and filtration properties were investigated and optimized. For this purpose, the Box-Behnken experimental design (BBD) was considered the best and therefore used. The PPS/PI fabrics were found to consistently have the highest air permeability, tensile strength and filtration performance, followed by the PPS fabrics and the PAN fabrics. As could be expected, an increase in area weight and water jet pressure generally resulted in a decrease in air permeability irrespective of the fabric types, this being due to the increased number of fibres and therefore greater fibre surface area and entanglement respectively. For fabric tensile strength, the effects of varying fabric area weight and water jet pressure were not so straight forward. For cross direction (CD) an increase in water jet pressure resulted in an increase tensile strength whereas in the machine direction (MD) there was a decrease when the water jet pressure was increased. The filtration efficiency and dust holding capacity of the fabrics were found to be around 96% and 211g/m2, respectively, with the exception of the PPS (500 g/m2 80 bar) fabrics. Increasing the amount of dust being fed to the fabric during each loading cycle, it caused an increase in pressure drop, as the fabrics became increasingly clogged forming a cake layer.
- Full Text:
- Date Issued: 2019
A framework for managing the impact of information communication technology on employee well-being
- Authors: Ackerman, Richard
- Date: 2018
- Subjects: Work environment -- Psychological aspects , Work -- Technological innovations Employees -- Mental health Job stress Flextime
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/21449 , vital:29523
- Description: Employees who work with Information Communication Technology (hereafter referred to as ICT) face a risk in a rise of portable work. This in turn provides a means for employees to be connected to work, even when at home. Flexible work solutions and ability to work any hour of the week creates non-standard work schedules, which in turn can lead to a condition of work-a-holism. In most cases, this phenomena is driven by the belief that being constantly available to work demonstrates a devotion to one’s career and employer. The higher demands placed on employees, are in most cases at the expense of employees’ health, work-life balance and overall well-being. The primary objective of this study is therefore to establish whether the use of ICT outside of normal working hours affects employee well-being, as measured in terms of work-life balance. The second objective of this study is to provide the Target Company within the automotive component supply industry located in Port Elizabeth, in the Republic of South Africa, with a framework for managing the impact of ICT on employee well-being. The research paper has been prompted by the Target Company having recently introduced flexible working solutions for its employees. Research on the topic of alternative forms of work schedules, has shown flexible working arrangements gives employees more choice and control over where, when and by how much they work. Flexibility allows employees to actively shape their working conditions which helps them solve the demands of integrating personal life and work commitments. Whether management should encourage or permit the use of ICT amongst its employees to extend beyond normal working hours however remains unclear. In order to answer the research questions, this study has applied a quantitative, positivistic and deductive research based methodology. The approach applied within this study included conducting an extensive literature review on the effects of ICT use after hours on employee well-being. Thereafter using literature as a foundation, a measuring instrument was constructed in the form of an online questionnaire. The questionnaire was emailed to respondents to collect primary data, in order to measure the dependent and independent variables in terms of the hypothesised relationships. Testing of the variables followed, in order to establish whether the use of ICT use after hours negatively impacts employee well-being as measured in terms of work-life balance and stress. Secondly, the study set out to establish whether flexible working conditions linked to ICT use after hours negatively impacts on employee work-life balance. Thirdly, the relationship between physiological aspects such as age, gender and ethnicity were interrogated to establish an employees’ ability to adapt to changing work conditions, brought about as a direct result of ICT. Lastly, this study set out to establish which ICT tool (email, cellular phone, smartphone or other) has the highest impact on employee wellness. The data collection process yielded a sample of 103 respondents in middle and senior management levels of the Target Company, with 97% being recipients of employer provided ICT tools. These respondents represented the employees who are most likely to be affected by the phenomena under investigation. The survey data was captured and analysed using descriptive statistical techniques. The interpretation revealed aspects which formed the basis for managerial recommendations in the form of a proposed framework to manage the impact of ICT on employee well-being. The findings of the study found that the use of ICT outside of normal working hours has a negative influence on employee well-being as measured in terms of work-life balance and stress. The literature review findings were confirmed as supporting the statement that flexible working conditions linked to ICT use after hours having a positive influence on employee work-life balance. A further finding of the study was the confirmation of physiological aspects affects an employees’ ability to adapt to changing working conditions, thereby having a negative influence on employee work-life balance. Lastly, to the question of which ICT tool has the biggest impact on well-being, it was found that differing ICT tools (email, cellular, smartphone, or other) do not have a negative influence on employee wellness. These findings formed the basis for the recommendations in the form of a framework which has been proposed to manage the impact of ICT on employee well-being. The most pertinent aspect of the framework includes the employer communicating a well-defined ICT usage policy, which clearly outlines a standard operating procedure in relation to ICT use to all its employees. The findings furthermore propose that the employer should take the time to explain and train its employees as to what is considered acceptable and non-acceptable use of ICT devices, especially in relation to after hour use and leave absences from work. To ensure employee well-being, employees should be encouraged to implement defined time blocks for when they are available for work and when they are not. This can be applied through the act of switching off their ICT devices, which constitutes a boundary work tactic as an action in order to prevent work-related interruptions in the private sphere. While the employer can take described measures, it should also be noted that there is responsibility on the part of the employee to ensure personal wellness, including regular exercise, relaxation, and taking appropriate breaks when necessary. Moreover, employees can apply work and life boundary management techniques through the selective use of devices. By not applying automatic work email updates on ICT devices such as smart phones is yet another boundary management technique which can be utilised by employees. There are a range of practical suggestions which are proposed as a method to minimize the risk of ICT use on employee well-being within this research document. The above proposals have only served to highlight a select few aspects. While it is acknowledged that there are important advantages associated with the development and use of ICT, it is equally important to allow employees to recharge their batteries in the form of appropriate downtime to regain perspective, thus allowing the organisation to maintain its competitive advantage, with the well-being of its employees taken to heart.
- Full Text:
- Date Issued: 2018
- Authors: Ackerman, Richard
- Date: 2018
- Subjects: Work environment -- Psychological aspects , Work -- Technological innovations Employees -- Mental health Job stress Flextime
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/21449 , vital:29523
- Description: Employees who work with Information Communication Technology (hereafter referred to as ICT) face a risk in a rise of portable work. This in turn provides a means for employees to be connected to work, even when at home. Flexible work solutions and ability to work any hour of the week creates non-standard work schedules, which in turn can lead to a condition of work-a-holism. In most cases, this phenomena is driven by the belief that being constantly available to work demonstrates a devotion to one’s career and employer. The higher demands placed on employees, are in most cases at the expense of employees’ health, work-life balance and overall well-being. The primary objective of this study is therefore to establish whether the use of ICT outside of normal working hours affects employee well-being, as measured in terms of work-life balance. The second objective of this study is to provide the Target Company within the automotive component supply industry located in Port Elizabeth, in the Republic of South Africa, with a framework for managing the impact of ICT on employee well-being. The research paper has been prompted by the Target Company having recently introduced flexible working solutions for its employees. Research on the topic of alternative forms of work schedules, has shown flexible working arrangements gives employees more choice and control over where, when and by how much they work. Flexibility allows employees to actively shape their working conditions which helps them solve the demands of integrating personal life and work commitments. Whether management should encourage or permit the use of ICT amongst its employees to extend beyond normal working hours however remains unclear. In order to answer the research questions, this study has applied a quantitative, positivistic and deductive research based methodology. The approach applied within this study included conducting an extensive literature review on the effects of ICT use after hours on employee well-being. Thereafter using literature as a foundation, a measuring instrument was constructed in the form of an online questionnaire. The questionnaire was emailed to respondents to collect primary data, in order to measure the dependent and independent variables in terms of the hypothesised relationships. Testing of the variables followed, in order to establish whether the use of ICT use after hours negatively impacts employee well-being as measured in terms of work-life balance and stress. Secondly, the study set out to establish whether flexible working conditions linked to ICT use after hours negatively impacts on employee work-life balance. Thirdly, the relationship between physiological aspects such as age, gender and ethnicity were interrogated to establish an employees’ ability to adapt to changing work conditions, brought about as a direct result of ICT. Lastly, this study set out to establish which ICT tool (email, cellular phone, smartphone or other) has the highest impact on employee wellness. The data collection process yielded a sample of 103 respondents in middle and senior management levels of the Target Company, with 97% being recipients of employer provided ICT tools. These respondents represented the employees who are most likely to be affected by the phenomena under investigation. The survey data was captured and analysed using descriptive statistical techniques. The interpretation revealed aspects which formed the basis for managerial recommendations in the form of a proposed framework to manage the impact of ICT on employee well-being. The findings of the study found that the use of ICT outside of normal working hours has a negative influence on employee well-being as measured in terms of work-life balance and stress. The literature review findings were confirmed as supporting the statement that flexible working conditions linked to ICT use after hours having a positive influence on employee work-life balance. A further finding of the study was the confirmation of physiological aspects affects an employees’ ability to adapt to changing working conditions, thereby having a negative influence on employee work-life balance. Lastly, to the question of which ICT tool has the biggest impact on well-being, it was found that differing ICT tools (email, cellular, smartphone, or other) do not have a negative influence on employee wellness. These findings formed the basis for the recommendations in the form of a framework which has been proposed to manage the impact of ICT on employee well-being. The most pertinent aspect of the framework includes the employer communicating a well-defined ICT usage policy, which clearly outlines a standard operating procedure in relation to ICT use to all its employees. The findings furthermore propose that the employer should take the time to explain and train its employees as to what is considered acceptable and non-acceptable use of ICT devices, especially in relation to after hour use and leave absences from work. To ensure employee well-being, employees should be encouraged to implement defined time blocks for when they are available for work and when they are not. This can be applied through the act of switching off their ICT devices, which constitutes a boundary work tactic as an action in order to prevent work-related interruptions in the private sphere. While the employer can take described measures, it should also be noted that there is responsibility on the part of the employee to ensure personal wellness, including regular exercise, relaxation, and taking appropriate breaks when necessary. Moreover, employees can apply work and life boundary management techniques through the selective use of devices. By not applying automatic work email updates on ICT devices such as smart phones is yet another boundary management technique which can be utilised by employees. There are a range of practical suggestions which are proposed as a method to minimize the risk of ICT use on employee well-being within this research document. The above proposals have only served to highlight a select few aspects. While it is acknowledged that there are important advantages associated with the development and use of ICT, it is equally important to allow employees to recharge their batteries in the form of appropriate downtime to regain perspective, thus allowing the organisation to maintain its competitive advantage, with the well-being of its employees taken to heart.
- Full Text:
- Date Issued: 2018
Auditory processing problems within the inclusive foundation phase classroom: an exploration of teachers' experiences
- Authors: Deysel, Sanet
- Date: 2016
- Subjects: Inclusive education , Early childhood special education , Early childhood teachers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/6834 , vital:21152
- Description: The Salamanca Statement (UNESCO, 1994) called upon all governments to implement inclusive education, ensuring that all learners with barriers to learning are included in the educational system. South Africa as a cosignatory to this global call responded with the implementation of the South African Education White Paper 6 (Department of Education, 2001) where the principles and foundations towards inclusive education were stipulated. It was expected of teachers to be able to accommodate learners with barriers to learning in their classrooms (Dednam, 2009, p. 371), although Ntombela and Green (2013, p. 2) state that teachers are not equipped to work with learners with specific disabilities. Learners present with various barriers to learning and these barriers pose problems and challenges in the classroom. One of these problems in the classroom is learners presenting with Auditory Processing Disorder. This qualitative study employed phenomenology as the research design. Through the use of memory work, drawings and focus group discussions as data production tools, the five Foundation Phase teachers’ experiences regarding learners presenting with Auditory Processing Disorder in the inclusive classroom, were explored. Bronfenbrenner’s ecological model was used to make meaning of the findings of the study. The findings of the study indicate that teachers are torn between the expectations of global and national policies regarding inclusive education and the management and support of learners presenting with Auditory Processing Disorder in their classrooms. Various challenges and problems arise with the inclusion of learners presenting with Auditory Processing Disorder in the classroom. The findings of the study were used to formulate guidelines to support Foundation Phase teachers working with learners presenting with auditory processing problems as well as policy suggestions for the Department of Basic Education. The Department of Basic Education should revise the implementation of CAPS to include the necessary adaptations for learners presenting with Auditory Processing Disorder; and also provide teacher assistants in Foundation Phase classrooms to enable the full inclusion of all learners.
- Full Text:
- Date Issued: 2016
- Authors: Deysel, Sanet
- Date: 2016
- Subjects: Inclusive education , Early childhood special education , Early childhood teachers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/6834 , vital:21152
- Description: The Salamanca Statement (UNESCO, 1994) called upon all governments to implement inclusive education, ensuring that all learners with barriers to learning are included in the educational system. South Africa as a cosignatory to this global call responded with the implementation of the South African Education White Paper 6 (Department of Education, 2001) where the principles and foundations towards inclusive education were stipulated. It was expected of teachers to be able to accommodate learners with barriers to learning in their classrooms (Dednam, 2009, p. 371), although Ntombela and Green (2013, p. 2) state that teachers are not equipped to work with learners with specific disabilities. Learners present with various barriers to learning and these barriers pose problems and challenges in the classroom. One of these problems in the classroom is learners presenting with Auditory Processing Disorder. This qualitative study employed phenomenology as the research design. Through the use of memory work, drawings and focus group discussions as data production tools, the five Foundation Phase teachers’ experiences regarding learners presenting with Auditory Processing Disorder in the inclusive classroom, were explored. Bronfenbrenner’s ecological model was used to make meaning of the findings of the study. The findings of the study indicate that teachers are torn between the expectations of global and national policies regarding inclusive education and the management and support of learners presenting with Auditory Processing Disorder in their classrooms. Various challenges and problems arise with the inclusion of learners presenting with Auditory Processing Disorder in the classroom. The findings of the study were used to formulate guidelines to support Foundation Phase teachers working with learners presenting with auditory processing problems as well as policy suggestions for the Department of Basic Education. The Department of Basic Education should revise the implementation of CAPS to include the necessary adaptations for learners presenting with Auditory Processing Disorder; and also provide teacher assistants in Foundation Phase classrooms to enable the full inclusion of all learners.
- Full Text:
- Date Issued: 2016
Modelling dispersal processes in impala-cheetah-lion ecosystems with infection in the lions
- Authors: Mbava, Willard
- Date: 2016
- Subjects: Predation (Biology) -- South Africa -- Kruger National Park Endangered species -- South Africa -- Kruger National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11782 , vital:26968
- Description: The study involved the predator-prey interaction of three species namely the predator (Cheetah Acinonyx jubatus), the super-predator (Lion Panthera leo), and their common prey (Impala Aepyceros melampus). The study area is the Kruger National Park. The predator being an endangered species, faces a survival problem. It is frequently killed by the super-predator to reduce competition for prey. The super-predator also scares away the predator o_ its kills. The prey forms the main diet of the predator. The plight of the predator motivated the author to formulate disease and reaction-diffusion models for the species interactions. The purpose of the models were to predict and explain the effect of large competition from the super-predator on the predator population. Important parameters related to additional predator mortality due to presence of super-predator, the disease incidence rate and induced death rate formed the focal points of the analysis. The dynamics of a predator-prey model with disease in super-predator were investigated. The super-predator species is infected with bovine Tuberculosis. In the study, the disease is considered as biological control to allow the predator population to regain from low numbers. The results highlight that in the absence of additional mortality on the predator by the super-predator, the predator population survives extinction. Furthermore, at current levels of disease incidence, the super-predator population is wiped out by the disease. However, the super-predator population survives extinction if the disease incidence rate is low. Persistence of all populations is possible in the case of low disease incidence rate and no additional mortality imparted on the predator. Furthermore, a two-species subsystem, prey and predator, is considered as a special case to determine the effect of super-predator removal from the system, on the survival of the predator. This is treated as a contrasting case from the smaller parks. The results show that the predator population thrives well in the total absence of its main competitor, with its population rising to at least twice the initial value. A reaction-diffusion three-species predator-prey model was formulated and analysed. Stability of the temporal and the spatio-temporal systems, existence and non-existence of stationary steady state solutions were studied. Conditions for the emergence of stationary patterns were deduced. The results show that by choosing the diffusion coeffcient d2 > _D 2 suffciently large, a non-constant positive solution is generated, that is, stationary patterns emerge, depicting dispersal of species. Predators were observed to occupy habitats surrounding prey. However, super-predators were observed to alternate their habitats, from staying away from prey to invading prey habitat. In the investigation, strategies to determine ways in which the predator species could be saved from extinction and its population improved were devised, and these included isolation of the predator from the super-predator.
- Full Text:
- Date Issued: 2016
- Authors: Mbava, Willard
- Date: 2016
- Subjects: Predation (Biology) -- South Africa -- Kruger National Park Endangered species -- South Africa -- Kruger National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11782 , vital:26968
- Description: The study involved the predator-prey interaction of three species namely the predator (Cheetah Acinonyx jubatus), the super-predator (Lion Panthera leo), and their common prey (Impala Aepyceros melampus). The study area is the Kruger National Park. The predator being an endangered species, faces a survival problem. It is frequently killed by the super-predator to reduce competition for prey. The super-predator also scares away the predator o_ its kills. The prey forms the main diet of the predator. The plight of the predator motivated the author to formulate disease and reaction-diffusion models for the species interactions. The purpose of the models were to predict and explain the effect of large competition from the super-predator on the predator population. Important parameters related to additional predator mortality due to presence of super-predator, the disease incidence rate and induced death rate formed the focal points of the analysis. The dynamics of a predator-prey model with disease in super-predator were investigated. The super-predator species is infected with bovine Tuberculosis. In the study, the disease is considered as biological control to allow the predator population to regain from low numbers. The results highlight that in the absence of additional mortality on the predator by the super-predator, the predator population survives extinction. Furthermore, at current levels of disease incidence, the super-predator population is wiped out by the disease. However, the super-predator population survives extinction if the disease incidence rate is low. Persistence of all populations is possible in the case of low disease incidence rate and no additional mortality imparted on the predator. Furthermore, a two-species subsystem, prey and predator, is considered as a special case to determine the effect of super-predator removal from the system, on the survival of the predator. This is treated as a contrasting case from the smaller parks. The results show that the predator population thrives well in the total absence of its main competitor, with its population rising to at least twice the initial value. A reaction-diffusion three-species predator-prey model was formulated and analysed. Stability of the temporal and the spatio-temporal systems, existence and non-existence of stationary steady state solutions were studied. Conditions for the emergence of stationary patterns were deduced. The results show that by choosing the diffusion coeffcient d2 > _D 2 suffciently large, a non-constant positive solution is generated, that is, stationary patterns emerge, depicting dispersal of species. Predators were observed to occupy habitats surrounding prey. However, super-predators were observed to alternate their habitats, from staying away from prey to invading prey habitat. In the investigation, strategies to determine ways in which the predator species could be saved from extinction and its population improved were devised, and these included isolation of the predator from the super-predator.
- Full Text:
- Date Issued: 2016
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