Characterisation of dissimilar friction stir welds between 5754 Aluminium alloy and C11000 copper
- Authors: Akinlabi, Esther Titilayo
- Date: 2010
- Subjects: Friction stir welding , Aluminum alloys , Copper alloys
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9629 , http://hdl.handle.net/10948/1536 , Friction stir welding , Aluminum alloys , Copper alloys
- Description: Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in 1991, for joining ferrous and non-ferrous materials1. The FSW of Aluminium and its alloys has been commercialised; and recent interest is focused on joining dissimilar materials. However, in order to commercialise the process, research studies are required to characterise and establish process windows. This research work through material characterisation of the welded joints establishes a process window for the Friction Stir welding of 5754 Aluminium Alloy and C11000 Copper. Furthermore, preliminary studies83,85 on the FSW of aluminium and copper have revealed the presence of intermetallic compounds which are detrimental to the weld qualities. This research work is also aimed at establishing process parameters that will result in limited or no intermetallic formation in the weld. The joint integrity of the resulting welds will also be correlated with the input process parameters. Based on the preliminary investigations conducted, a final weld matrix consisting of twenty seven welds was produced by varying the rotational speed between 600 and 1200 rpm, and the feed rate between 50 and 300 mm/min using three different shoulder diameter tools – 15, 18 and 25 mm to compare the heat input into the welds and to achieve the best results. The welds were characterised through microstructural evaluation, tensile testing, microhardness profiling, X-Ray Diffraction analysis, electrical resistivity and statistical analysis – in order to establish the interrelationship between the process parameters and the weld qualities. viii Microstructural evaluation of the weld samples revealed that the interfacial regions are characterised by mixture layers of aluminium and copper; while 33 percent of the tensile samples are within the acceptable range (> 75 percent joint efficiency). High Vickers microhardness values were measured at the joint interfaces, which corresponded with the intermetallic compounds. The Energy Dispersive Spectroscopy analysis revealed the presence of thin layers of intermetallics in nanoscale at the interfacial regions. The diffractograms of the X-Ray Diffraction analysis showed small peaks for intermetallics in some of the welds. Low electrical resistivities were measured at the joint interfaces. The statistical analysis showed that the downward vertical force, (Fz) can significantly influence the resulting weld qualities. An overall summary of the analysis of the weld qualities - with respect to the shoulder diameter tools employed showed that the 18 mm shoulder diameter tool is most appropriate among the three shoulder diameters considered, and a process window of medium spindle speed of 950 rpm and low-to-medium feed rate between 50 and 150 mm/min is established for FSW of Aluminium and Copper. Welds produced at 1200 rpm and 300 mm/min with low heat input did not have intermetallics formed at the joint interface.
- Full Text:
- Date Issued: 2010
- Authors: Akinlabi, Esther Titilayo
- Date: 2010
- Subjects: Friction stir welding , Aluminum alloys , Copper alloys
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9629 , http://hdl.handle.net/10948/1536 , Friction stir welding , Aluminum alloys , Copper alloys
- Description: Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in 1991, for joining ferrous and non-ferrous materials1. The FSW of Aluminium and its alloys has been commercialised; and recent interest is focused on joining dissimilar materials. However, in order to commercialise the process, research studies are required to characterise and establish process windows. This research work through material characterisation of the welded joints establishes a process window for the Friction Stir welding of 5754 Aluminium Alloy and C11000 Copper. Furthermore, preliminary studies83,85 on the FSW of aluminium and copper have revealed the presence of intermetallic compounds which are detrimental to the weld qualities. This research work is also aimed at establishing process parameters that will result in limited or no intermetallic formation in the weld. The joint integrity of the resulting welds will also be correlated with the input process parameters. Based on the preliminary investigations conducted, a final weld matrix consisting of twenty seven welds was produced by varying the rotational speed between 600 and 1200 rpm, and the feed rate between 50 and 300 mm/min using three different shoulder diameter tools – 15, 18 and 25 mm to compare the heat input into the welds and to achieve the best results. The welds were characterised through microstructural evaluation, tensile testing, microhardness profiling, X-Ray Diffraction analysis, electrical resistivity and statistical analysis – in order to establish the interrelationship between the process parameters and the weld qualities. viii Microstructural evaluation of the weld samples revealed that the interfacial regions are characterised by mixture layers of aluminium and copper; while 33 percent of the tensile samples are within the acceptable range (> 75 percent joint efficiency). High Vickers microhardness values were measured at the joint interfaces, which corresponded with the intermetallic compounds. The Energy Dispersive Spectroscopy analysis revealed the presence of thin layers of intermetallics in nanoscale at the interfacial regions. The diffractograms of the X-Ray Diffraction analysis showed small peaks for intermetallics in some of the welds. Low electrical resistivities were measured at the joint interfaces. The statistical analysis showed that the downward vertical force, (Fz) can significantly influence the resulting weld qualities. An overall summary of the analysis of the weld qualities - with respect to the shoulder diameter tools employed showed that the 18 mm shoulder diameter tool is most appropriate among the three shoulder diameters considered, and a process window of medium spindle speed of 950 rpm and low-to-medium feed rate between 50 and 150 mm/min is established for FSW of Aluminium and Copper. Welds produced at 1200 rpm and 300 mm/min with low heat input did not have intermetallics formed at the joint interface.
- Full Text:
- Date Issued: 2010
Developing an e-health framework through electronic healthcare readiness assessment
- Authors: Coleman, Alfred
- Date: 2010
- Subjects: Health -- Computer network resources , Medical care -- South Africa -- Computer network resources , Public health -- South Africa -- Computer network resources , Internet in medicine -- South Africa , Medical informatics -- South Africa , Telecommunication in medicine -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9729 , http://hdl.handle.net/10948/1519 , Health -- Computer network resources , Medical care -- South Africa -- Computer network resources , Public health -- South Africa -- Computer network resources , Internet in medicine -- South Africa , Medical informatics -- South Africa , Telecommunication in medicine -- South Africa
- Description: The major socio-economic development challenges facing most African countries include economic diversification, poverty, unemployment, diseases and the unsustainable use of natural resources. The challenge of quality healthcare provisioning is compounded by the HIV/AIDS pandemic in Sub Saharan Africa. However, there is a great potential in using electronic healthcare (e-health) as one of the supportive systems within the healthcare sector to address these pressing challenges facing healthcare systems in developing countries, including solving inequalities in healthcare delivery between rural and urban hospitals/clinics. The purpose of this study was to compile a Provincial E-health Framework (PEHF) based on the feedback from electronic healthcare readiness assessments conducted in selected rural and urban hospitals/clinics in the North West Province in South Africa. The e-healthcare readiness assessment was conducted in the light of effective use of ICT in patient healthcare record system, consultation among healthcare professionals, prescription of medication, referral of patients and training of healthcare professionals in ICT usage. The study was divided into two phases which were phases 1 and 2 and a qualitative design supported by a case study approach was used. Data were collected using different techniques to enhance triangulation of data. The techniques included group interviews, qualitative questionnaires, photographs, document analysis and expert opinions. The outcome of the assessment led to the compilation of the PEHF which was based on Service Oriented Architecture (SOA). SOA was chosen to integrate the hospitals/clinics‟ ICT infrastructure yet allowing each hospital/clinic the autonomy to control its own ICT environment. To assist hospitals/clinics integrate their ICT resources, this research study proposed an Infrastructure Network Architecture which clustered hospitals/clinics to share common ICT infrastructure instead of duplicating these resources. Furthermore, processes of the e-health services (e-patient health IV record system, e-consultation system, e-prescription system, e-referral system and e-training system) were provided to assist in the implementation of the PEHF. Finally, a set of guidelines were provided by the research study to aid the implementation of the PEHF.
- Full Text:
- Date Issued: 2010
- Authors: Coleman, Alfred
- Date: 2010
- Subjects: Health -- Computer network resources , Medical care -- South Africa -- Computer network resources , Public health -- South Africa -- Computer network resources , Internet in medicine -- South Africa , Medical informatics -- South Africa , Telecommunication in medicine -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9729 , http://hdl.handle.net/10948/1519 , Health -- Computer network resources , Medical care -- South Africa -- Computer network resources , Public health -- South Africa -- Computer network resources , Internet in medicine -- South Africa , Medical informatics -- South Africa , Telecommunication in medicine -- South Africa
- Description: The major socio-economic development challenges facing most African countries include economic diversification, poverty, unemployment, diseases and the unsustainable use of natural resources. The challenge of quality healthcare provisioning is compounded by the HIV/AIDS pandemic in Sub Saharan Africa. However, there is a great potential in using electronic healthcare (e-health) as one of the supportive systems within the healthcare sector to address these pressing challenges facing healthcare systems in developing countries, including solving inequalities in healthcare delivery between rural and urban hospitals/clinics. The purpose of this study was to compile a Provincial E-health Framework (PEHF) based on the feedback from electronic healthcare readiness assessments conducted in selected rural and urban hospitals/clinics in the North West Province in South Africa. The e-healthcare readiness assessment was conducted in the light of effective use of ICT in patient healthcare record system, consultation among healthcare professionals, prescription of medication, referral of patients and training of healthcare professionals in ICT usage. The study was divided into two phases which were phases 1 and 2 and a qualitative design supported by a case study approach was used. Data were collected using different techniques to enhance triangulation of data. The techniques included group interviews, qualitative questionnaires, photographs, document analysis and expert opinions. The outcome of the assessment led to the compilation of the PEHF which was based on Service Oriented Architecture (SOA). SOA was chosen to integrate the hospitals/clinics‟ ICT infrastructure yet allowing each hospital/clinic the autonomy to control its own ICT environment. To assist hospitals/clinics integrate their ICT resources, this research study proposed an Infrastructure Network Architecture which clustered hospitals/clinics to share common ICT infrastructure instead of duplicating these resources. Furthermore, processes of the e-health services (e-patient health IV record system, e-consultation system, e-prescription system, e-referral system and e-training system) were provided to assist in the implementation of the PEHF. Finally, a set of guidelines were provided by the research study to aid the implementation of the PEHF.
- Full Text:
- Date Issued: 2010
Fostering information security culture through intergrating theory and technology
- Van Niekerk, Johannes Frederick
- Authors: Van Niekerk, Johannes Frederick
- Date: 2010
- Subjects: Information technology -- Security measures , Data protection , Corporate culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9754 , http://hdl.handle.net/10948/1404 , Information technology -- Security measures , Data protection , Corporate culture -- South Africa
- Description: Today information can be seen as a basic commodity that is crucial to the continuous well-being of modern organizations. Many modern organizations will be unable to do business without access to their information resources. It is therefor of vital importance for organizations to ensure that their infor- mation resources are adequately protected against both internal and external threats. This protection of information resources is known as information security and is, to a large extent, dependent on the behavior of humans in the organization. Humans, at various levels in the organization, play vital roles in the pro- cesses that secure organizational information resources. Many of the prob- lems experienced in information security can be directly contributed to the humans involved in the process. Employees, either intentionally or through negligence, often due to a lack of knowledge, can be seen as the greatest threat to information security. Addressing this human factor in information security is the primary focus of this thesis. The majority of current approaches to dealing with the human factors in information security acknowledge the need to foster an information security culture in the organization. However, very few current approaches attempt to adjust the "generic" model(s) used to define organizational culture to be specific to the needs of information security. This thesis firstly proposes, and argues, such an adapted conceptual model which aims to improve the understanding of what an information security culture is. The thesis secondly focuses on the underlying role that information security educational programs play in the fostering of an organizational information security culture. It is argued that many current information security edu- cational programs are not based on sound pedagogical theory. The use of learning taxonomies during the design of information security educational programs is proposed as a possible way to improve the pedagogical rigor of such programs. The thesis also argues in favor of the use of blended and/or e-learning approaches for the delivery of information security educational content. Finally, this thesis provides a detailed overview demonstrating how the various elements contributed by the thesis integrates into existing trans- formative change management processes for the fostering of an organizational information security culture.
- Full Text:
- Date Issued: 2010
- Authors: Van Niekerk, Johannes Frederick
- Date: 2010
- Subjects: Information technology -- Security measures , Data protection , Corporate culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9754 , http://hdl.handle.net/10948/1404 , Information technology -- Security measures , Data protection , Corporate culture -- South Africa
- Description: Today information can be seen as a basic commodity that is crucial to the continuous well-being of modern organizations. Many modern organizations will be unable to do business without access to their information resources. It is therefor of vital importance for organizations to ensure that their infor- mation resources are adequately protected against both internal and external threats. This protection of information resources is known as information security and is, to a large extent, dependent on the behavior of humans in the organization. Humans, at various levels in the organization, play vital roles in the pro- cesses that secure organizational information resources. Many of the prob- lems experienced in information security can be directly contributed to the humans involved in the process. Employees, either intentionally or through negligence, often due to a lack of knowledge, can be seen as the greatest threat to information security. Addressing this human factor in information security is the primary focus of this thesis. The majority of current approaches to dealing with the human factors in information security acknowledge the need to foster an information security culture in the organization. However, very few current approaches attempt to adjust the "generic" model(s) used to define organizational culture to be specific to the needs of information security. This thesis firstly proposes, and argues, such an adapted conceptual model which aims to improve the understanding of what an information security culture is. The thesis secondly focuses on the underlying role that information security educational programs play in the fostering of an organizational information security culture. It is argued that many current information security edu- cational programs are not based on sound pedagogical theory. The use of learning taxonomies during the design of information security educational programs is proposed as a possible way to improve the pedagogical rigor of such programs. The thesis also argues in favor of the use of blended and/or e-learning approaches for the delivery of information security educational content. Finally, this thesis provides a detailed overview demonstrating how the various elements contributed by the thesis integrates into existing trans- formative change management processes for the fostering of an organizational information security culture.
- Full Text:
- Date Issued: 2010
Influences on construction project delivery time
- Authors: Olatunji, Aiyetan Ayodeji
- Date: 2010
- Subjects: Construction industry -- South Africa -- Management , Project management -- South Africa , Construction industry -- Economic aspects -- South Africa , Construction industry -- Technological innovations -- South Africa , Construction industry -- Labor productivity -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9681 , http://hdl.handle.net/10948/1548 , Construction industry -- South Africa -- Management , Project management -- South Africa , Construction industry -- Economic aspects -- South Africa , Construction industry -- Technological innovations -- South Africa , Construction industry -- Labor productivity -- South Africa
- Description: Construction delays are a global phenomenon. Factors causing construction delays in construction projects differ from country to country, due to different prevailing conditions. The prevailing conditions that could exert an influence on project delivery time are: political, economic, and physical factors as well as level of technological development; management style, and construction techniques. The construction industry is a major player in the economy, generating both employment and wealth. However, many projects experience extensive delays and thereby exceed initial time and cost estimates. This study aims at determining the causes of delays in project delivery in South Africa; evolving interventions, and developing a model for the delivery of projects on time. Inferential and linear regression statistical tools were used in the analysis of data for the study. The sample population consists of architects, builders, quantity surveyors, structural engineers, and clients, and the metropolitan cities of five provinces constituted the geographical delimitation of the study. The provinces are: Eastern Cape; Free State; Gauteng; KwaZulu-Natal, and Western Cape. The metropolitan cities are: Bloemfontein; Cape Town; Durban; Johannesburg, and Port Elizabeth. Findings which negatively influence project delivery time in South Africa include the following: lack of adequate planning; management style; the lack of constructability reviews of designs; inadequate motivation of workers; economic policies; lack of prompt payment to contractors, and quality of management during design and construction. Recommendations include: (1) The introduction of the following courses in built environment tertiary education � quality management competences; operational planning; design management, and generic management; (2) pre-qualification of suppliers; (3) inclusion of the following in tender documentation � human resource schedule; plant and equipment schedule; quality assurance plan, and work schedule; (4) appointment of materials specialists on a large projects; (5) the model developed should be adopted for use in the South African construction industry for the delivery of projects on time, and (6) the linear regression equation: Y = 13.1159 + 1.1341x or 35.3 percent addition on time for the estimation of project delivery time.
- Full Text:
- Date Issued: 2010
- Authors: Olatunji, Aiyetan Ayodeji
- Date: 2010
- Subjects: Construction industry -- South Africa -- Management , Project management -- South Africa , Construction industry -- Economic aspects -- South Africa , Construction industry -- Technological innovations -- South Africa , Construction industry -- Labor productivity -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9681 , http://hdl.handle.net/10948/1548 , Construction industry -- South Africa -- Management , Project management -- South Africa , Construction industry -- Economic aspects -- South Africa , Construction industry -- Technological innovations -- South Africa , Construction industry -- Labor productivity -- South Africa
- Description: Construction delays are a global phenomenon. Factors causing construction delays in construction projects differ from country to country, due to different prevailing conditions. The prevailing conditions that could exert an influence on project delivery time are: political, economic, and physical factors as well as level of technological development; management style, and construction techniques. The construction industry is a major player in the economy, generating both employment and wealth. However, many projects experience extensive delays and thereby exceed initial time and cost estimates. This study aims at determining the causes of delays in project delivery in South Africa; evolving interventions, and developing a model for the delivery of projects on time. Inferential and linear regression statistical tools were used in the analysis of data for the study. The sample population consists of architects, builders, quantity surveyors, structural engineers, and clients, and the metropolitan cities of five provinces constituted the geographical delimitation of the study. The provinces are: Eastern Cape; Free State; Gauteng; KwaZulu-Natal, and Western Cape. The metropolitan cities are: Bloemfontein; Cape Town; Durban; Johannesburg, and Port Elizabeth. Findings which negatively influence project delivery time in South Africa include the following: lack of adequate planning; management style; the lack of constructability reviews of designs; inadequate motivation of workers; economic policies; lack of prompt payment to contractors, and quality of management during design and construction. Recommendations include: (1) The introduction of the following courses in built environment tertiary education � quality management competences; operational planning; design management, and generic management; (2) pre-qualification of suppliers; (3) inclusion of the following in tender documentation � human resource schedule; plant and equipment schedule; quality assurance plan, and work schedule; (4) appointment of materials specialists on a large projects; (5) the model developed should be adopted for use in the South African construction industry for the delivery of projects on time, and (6) the linear regression equation: Y = 13.1159 + 1.1341x or 35.3 percent addition on time for the estimation of project delivery time.
- Full Text:
- Date Issued: 2010
The adoption of quality assurance in e-Health acquisition for rural hospitals in the Eastern Cape Province
- Authors: Ruxwana, Nkqubela
- Date: 2010
- Subjects: Quality assurance -- Management , Hospital care -- Quality control , Health facilities -- Quality control , Health -- Computer network resources , Public health -- Information services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9731 , http://hdl.handle.net/10948/1514 , Quality assurance -- Management , Hospital care -- Quality control , Health facilities -- Quality control , Health -- Computer network resources , Public health -- Information services
- Description: The evolution of e-health has the potential to assist in the management of scarce resources and the shortage of skills, enhance efficiencies, improve quality and increase work productivity within the healthcare sector. As a result, an increase is seen in e-health solutions developments with the aim to improve healthcare services, hospital information systems, health decision support, telemedicine and other technical systems that have the potential to reduce cost, improve quality, and enhance the accessibility and delivery of healthcare. However, unfortunately their implementation contiues to fail. Although there are several reasons for this, in this study a lack of project quality management is viewed as a key contributor to the failure of e-health solutions implementation projects in rural hospitals. This results in neglected aspects of quality assurance (QA), which forms an integral part of project quality management. The purpose of this study is to develop a Genertic Quality Assurance Model (GQAM) for the successful acquisition (i.e. development and implementation) of e-health solutions in rural hospitals in the Eastern Cape Province to enable improved quality of care and service delivery. In order to develop and test this model it was necessary to identify the QA methodologies that are currently used in rural hospitals and to evaluate their strengths and weaknesses, as well as their impact on project success. The study is divided into four phases; in each phase different study designs were followed. The study used triangulation of qualitative and some elements of quantitative research approaches, in terms of which a case study approach was adpoted to answer the research questions. This study did indeed develop a GQAM that can be used to ensure e-health solution success in rural hospitals. Furthermore, to aid in the implementation of this model, a set of QA value chain implementation guidelines were developed, as a framework, to inject the nodel into typical (SDLC) phases.
- Full Text:
- Date Issued: 2010
- Authors: Ruxwana, Nkqubela
- Date: 2010
- Subjects: Quality assurance -- Management , Hospital care -- Quality control , Health facilities -- Quality control , Health -- Computer network resources , Public health -- Information services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9731 , http://hdl.handle.net/10948/1514 , Quality assurance -- Management , Hospital care -- Quality control , Health facilities -- Quality control , Health -- Computer network resources , Public health -- Information services
- Description: The evolution of e-health has the potential to assist in the management of scarce resources and the shortage of skills, enhance efficiencies, improve quality and increase work productivity within the healthcare sector. As a result, an increase is seen in e-health solutions developments with the aim to improve healthcare services, hospital information systems, health decision support, telemedicine and other technical systems that have the potential to reduce cost, improve quality, and enhance the accessibility and delivery of healthcare. However, unfortunately their implementation contiues to fail. Although there are several reasons for this, in this study a lack of project quality management is viewed as a key contributor to the failure of e-health solutions implementation projects in rural hospitals. This results in neglected aspects of quality assurance (QA), which forms an integral part of project quality management. The purpose of this study is to develop a Genertic Quality Assurance Model (GQAM) for the successful acquisition (i.e. development and implementation) of e-health solutions in rural hospitals in the Eastern Cape Province to enable improved quality of care and service delivery. In order to develop and test this model it was necessary to identify the QA methodologies that are currently used in rural hospitals and to evaluate their strengths and weaknesses, as well as their impact on project success. The study is divided into four phases; in each phase different study designs were followed. The study used triangulation of qualitative and some elements of quantitative research approaches, in terms of which a case study approach was adpoted to answer the research questions. This study did indeed develop a GQAM that can be used to ensure e-health solution success in rural hospitals. Furthermore, to aid in the implementation of this model, a set of QA value chain implementation guidelines were developed, as a framework, to inject the nodel into typical (SDLC) phases.
- Full Text:
- Date Issued: 2010
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