Improving construction planning through 4D planning
- Authors: Allen, Christopher James
- Date: 2007
- Subjects: Construction industry -- Management , Construction industry -- Computer-aided design
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9698 , http://hdl.handle.net/10948/467 , http://hdl.handle.net/10948/d1011923 , Construction industry -- Management , Construction industry -- Computer-aided design
- Description: Construction Planning will increasingly play a more critical role within the realm of the Built Environment. Existing practices used to plan and communicate the construction process to be undertaken are failing to deliver the desired results for construction companies and clients alike. At a time of unprecedented growth in the industry around the world, which is leading to a general skills shortage, especially in management positions, construction planners are increasingly being asked to deal with more responsibility. As with other industries, technological improvement in the tools at their disposal is one way to address the inadequacies of the present situation. Increasingly, three dimensional design packages are being used to generate construction information which can then be used for quantities calculations, automated manufacturing processes and construction simulation. The latter forms the basis for their use in the process of planning, through new technologies being developed as virtual construction tools or 4D planning, the addition of time to the 3D model environment, but using the elements within the model as the basis for the construction programme. The benefit of using the design information to form the basis of the programme is that the interface tasks and logistical activities, as well as location related constraints, can be identified and then communicated to all levels within the construction team through a time based visual image. The purpose of this study is therefore to establish a scientifically analysed alternative method for the creation, review and delivery of construction programmes. In order to achieve the research objectives, three methodologies have been employed. Firstly, the literature review in the fields of planning including existing methodologies and previous research of 4D related techniques has been analysed. An overview of the perceived weaknesses to current practises and proposed solution will be explored and best case scenarios outlined and further investigated. Secondly, the 51 Lime Street project provides an environment in which the proposed 4D planning techniques have been implemented and the benefits of the process can, through observation / participation methodology, be validated. Thirdly, through interview questionnaires, with Lime St contractors and management, and e-mail questionnaires to a broader sample stratum, data on the ability of the tools, the techniques employed on 51 Lime Street and similar projects have been collated and statistically analysed to validate the reliability and relevance for future implementation. The result of the research will provide management teams with a practical alternative to existing planning methodologies. Construction planners will have alternative technique that can further enhance their role within the project team whilst increasing their ability to communicate the team’s vision to a wider audience, making them and the project more efficient and effective in the process. It has been proposed that clients insist on the use of 3D from the commencement of the design process so that this information can be passed downstream through the construction process and onto facilities management. Planners need to be able to communicate their requirements better and the 4D planning models provide both a more inclusive way of planning alongside a better communications medium in the form of moving images. A picture tells a thousand words.
- Full Text:
- Date Issued: 2007
- Authors: Allen, Christopher James
- Date: 2007
- Subjects: Construction industry -- Management , Construction industry -- Computer-aided design
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9698 , http://hdl.handle.net/10948/467 , http://hdl.handle.net/10948/d1011923 , Construction industry -- Management , Construction industry -- Computer-aided design
- Description: Construction Planning will increasingly play a more critical role within the realm of the Built Environment. Existing practices used to plan and communicate the construction process to be undertaken are failing to deliver the desired results for construction companies and clients alike. At a time of unprecedented growth in the industry around the world, which is leading to a general skills shortage, especially in management positions, construction planners are increasingly being asked to deal with more responsibility. As with other industries, technological improvement in the tools at their disposal is one way to address the inadequacies of the present situation. Increasingly, three dimensional design packages are being used to generate construction information which can then be used for quantities calculations, automated manufacturing processes and construction simulation. The latter forms the basis for their use in the process of planning, through new technologies being developed as virtual construction tools or 4D planning, the addition of time to the 3D model environment, but using the elements within the model as the basis for the construction programme. The benefit of using the design information to form the basis of the programme is that the interface tasks and logistical activities, as well as location related constraints, can be identified and then communicated to all levels within the construction team through a time based visual image. The purpose of this study is therefore to establish a scientifically analysed alternative method for the creation, review and delivery of construction programmes. In order to achieve the research objectives, three methodologies have been employed. Firstly, the literature review in the fields of planning including existing methodologies and previous research of 4D related techniques has been analysed. An overview of the perceived weaknesses to current practises and proposed solution will be explored and best case scenarios outlined and further investigated. Secondly, the 51 Lime Street project provides an environment in which the proposed 4D planning techniques have been implemented and the benefits of the process can, through observation / participation methodology, be validated. Thirdly, through interview questionnaires, with Lime St contractors and management, and e-mail questionnaires to a broader sample stratum, data on the ability of the tools, the techniques employed on 51 Lime Street and similar projects have been collated and statistically analysed to validate the reliability and relevance for future implementation. The result of the research will provide management teams with a practical alternative to existing planning methodologies. Construction planners will have alternative technique that can further enhance their role within the project team whilst increasing their ability to communicate the team’s vision to a wider audience, making them and the project more efficient and effective in the process. It has been proposed that clients insist on the use of 3D from the commencement of the design process so that this information can be passed downstream through the construction process and onto facilities management. Planners need to be able to communicate their requirements better and the 4D planning models provide both a more inclusive way of planning alongside a better communications medium in the form of moving images. A picture tells a thousand words.
- Full Text:
- Date Issued: 2007
The design, management and testing of a solar vehicle's energy strategy
- Authors: Jordaan, Johan
- Date: 2016
- Subjects: Solar energy -- Hybrid systems , Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7428 , vital:21362
- Description: In recent years the interest in implementing solar energy on vehicles (electrical and hybrid) has grown significantly [1]. There are currently limitations in this sector, such as the low energy density (efficiency of conversion) of this source, but it is still a renewable resource and as such, there is a growing interest [1]. A “smart” energy strategy implemented on a solar/electrical vehicle, in order to increase its energy harvesting volume, could enhance the growth of this sector. A tracking algorithm for a solar vehicle’s MPPT (Maximum Power Point Tracker) can be designed to source solar energy very effectively and to increase the speed of finding (tracking) this optimal sourcing point (solar panel voltage and current). Even though there are many different MPPT algorithms, it was decided that most of them were designed for stationary MPPT applications and the dynamics of implementing a MPPT on a vehicle create some unique scenarios. These include: Shadow flicker. This is rhythmic, rapid moving shadows across a solar panel, such as shadows from a line of trees: Rapid changes in solar panel orientation due to the road surface/relief; Rapid changes in panel temperature due to the location of the vehicle. The aim of the research can be divided into three outcomes: 1 Creating a “Smart” energy strategy/control, 2 Implement the new control system on a solar vehicle’s MPPT, and 3 Harvesting maximum energy from solar panels using the new energy strategy. The term “smart” is used to indicate the ability of the MPPT algorithm to be updated and improved based on previous results. A MPPT and scaled solar vehicle is designed and manufactured in order to test the MPPT algorithm. The purpose of using a self-developed experimental setup is to have more control over the system variables as well as having the maximum freedom in setting up the system parameters.
- Full Text:
- Date Issued: 2016
- Authors: Jordaan, Johan
- Date: 2016
- Subjects: Solar energy -- Hybrid systems , Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7428 , vital:21362
- Description: In recent years the interest in implementing solar energy on vehicles (electrical and hybrid) has grown significantly [1]. There are currently limitations in this sector, such as the low energy density (efficiency of conversion) of this source, but it is still a renewable resource and as such, there is a growing interest [1]. A “smart” energy strategy implemented on a solar/electrical vehicle, in order to increase its energy harvesting volume, could enhance the growth of this sector. A tracking algorithm for a solar vehicle’s MPPT (Maximum Power Point Tracker) can be designed to source solar energy very effectively and to increase the speed of finding (tracking) this optimal sourcing point (solar panel voltage and current). Even though there are many different MPPT algorithms, it was decided that most of them were designed for stationary MPPT applications and the dynamics of implementing a MPPT on a vehicle create some unique scenarios. These include: Shadow flicker. This is rhythmic, rapid moving shadows across a solar panel, such as shadows from a line of trees: Rapid changes in solar panel orientation due to the road surface/relief; Rapid changes in panel temperature due to the location of the vehicle. The aim of the research can be divided into three outcomes: 1 Creating a “Smart” energy strategy/control, 2 Implement the new control system on a solar vehicle’s MPPT, and 3 Harvesting maximum energy from solar panels using the new energy strategy. The term “smart” is used to indicate the ability of the MPPT algorithm to be updated and improved based on previous results. A MPPT and scaled solar vehicle is designed and manufactured in order to test the MPPT algorithm. The purpose of using a self-developed experimental setup is to have more control over the system variables as well as having the maximum freedom in setting up the system parameters.
- Full Text:
- Date Issued: 2016
Mechanisms, analysis and characterisation of mechanical properties of laser formed commercially pure grade 2 titanium alloy plates
- Authors: Mjali, Kadephi Vuyolwethu
- Date: 2014
- Subjects: Materials -- Mechanical properties , Bending , Titanium-aluminum alloys
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9641 , http://hdl.handle.net/10948/d1021083
- Description: The processing of materials has become a specialist field and the industry will continue to grow due to rising costs in labour and raw materials which has forced many automotive industry suppliers to invest heavily in this field. In order to be relevant and competitive in today’s industrial world, companies in South Africa are now forced to dedicate billions of rands in profits to research and development. Metals like titanium are finding favour with automotive and aviation companies in pursuit of savings in fuel consumption. This saving is achieved by reducing weight on aircraft and automobiles yet still meeting acceptable and improved structural integrity. In-depth research into the behaviour of various materials under varying loading conditions is therefore essential. The study on the processing of commercially pure grade 2 titanium alloy plates focuses on the development of process parameters for bending the material using a 4kW Nd: YAG laser to an approximate radius of curvature of 120mm. The resulting mechanical properties of laser formed plates are then compared to those obtained from mechanically formed samples. The titanium parent material was used to benchmark the performance of formed samples. The effect of process parameters on the mechanical properties and structural integrity also formed part of this study. To obtain the bending parameters for laser forming, various combinations of processing speeds and laser powers were used. The line energy is dependent on the power and scanning velocity parameters and these are shown in table 1. The laser power, line energy and scanning velocity were the main parameters controlled in this study and the beam diameter remained unchanged. Residual stress analysis, micro-hardness and fatigue life testing were carried out to analyse mechanical properties and the structural integrity of the plate samples. Microstructural analysis was also done to observe changes in the material as a result of the forming processes. From the results it is evident that laser forming is beneficial to the hardness of titanium but detrimental to the fatigue life at higher line energies. Residual stress analysis showed the amount of stress within the study samples increased with each forming operation. This information was vital in the analysis of the fatigue life of titanium. A fatigue life prediction model was developed from this study and it shed some light on the behaviour of titanium in fatigue testing. The model could be used to predict fatigue life when no fatigue data is available for commercially pure grade 2 titanium alloy plates. In conclusion, this study helped establish parameters that could be used to bend titanium while the analysis of mechanical properties showed the limits of working with this alloy.
- Full Text:
- Date Issued: 2014
- Authors: Mjali, Kadephi Vuyolwethu
- Date: 2014
- Subjects: Materials -- Mechanical properties , Bending , Titanium-aluminum alloys
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9641 , http://hdl.handle.net/10948/d1021083
- Description: The processing of materials has become a specialist field and the industry will continue to grow due to rising costs in labour and raw materials which has forced many automotive industry suppliers to invest heavily in this field. In order to be relevant and competitive in today’s industrial world, companies in South Africa are now forced to dedicate billions of rands in profits to research and development. Metals like titanium are finding favour with automotive and aviation companies in pursuit of savings in fuel consumption. This saving is achieved by reducing weight on aircraft and automobiles yet still meeting acceptable and improved structural integrity. In-depth research into the behaviour of various materials under varying loading conditions is therefore essential. The study on the processing of commercially pure grade 2 titanium alloy plates focuses on the development of process parameters for bending the material using a 4kW Nd: YAG laser to an approximate radius of curvature of 120mm. The resulting mechanical properties of laser formed plates are then compared to those obtained from mechanically formed samples. The titanium parent material was used to benchmark the performance of formed samples. The effect of process parameters on the mechanical properties and structural integrity also formed part of this study. To obtain the bending parameters for laser forming, various combinations of processing speeds and laser powers were used. The line energy is dependent on the power and scanning velocity parameters and these are shown in table 1. The laser power, line energy and scanning velocity were the main parameters controlled in this study and the beam diameter remained unchanged. Residual stress analysis, micro-hardness and fatigue life testing were carried out to analyse mechanical properties and the structural integrity of the plate samples. Microstructural analysis was also done to observe changes in the material as a result of the forming processes. From the results it is evident that laser forming is beneficial to the hardness of titanium but detrimental to the fatigue life at higher line energies. Residual stress analysis showed the amount of stress within the study samples increased with each forming operation. This information was vital in the analysis of the fatigue life of titanium. A fatigue life prediction model was developed from this study and it shed some light on the behaviour of titanium in fatigue testing. The model could be used to predict fatigue life when no fatigue data is available for commercially pure grade 2 titanium alloy plates. In conclusion, this study helped establish parameters that could be used to bend titanium while the analysis of mechanical properties showed the limits of working with this alloy.
- Full Text:
- Date Issued: 2014
Professional, personal and corporate ethics challenges during infrastructure delivery
- Authors: Dyariwe, Abongile
- Date: 2015-01
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53300 , vital:45131
- Description: Purpose of this treatise: This study is aimed at investigating whether there is a lack of professional- and, personal ethics, and a lack of enforcing corporate ethics from the Built environment professionals working for Eskom ECOU. Design/methodology/approach: The research approach used for the study was mainly quantitative. The quantitative methods used were descriptive and non-parametric statistical methods (Kruskal- Wallis Test and Mann-Whitney U Test). The selected sample for the study was categorised as internal stakeholders (i.e. employees that are permanently employed by Eskom) and external stakeholders (i.e. people that are employed by Eskom on a contract basis as quantity surveying, project management and engineering consultants) The scope of the study was to determine whether there are professional-, personal- and corporate ethical challenges in client organisations. A literature review was conducted; and all the relevant literature relating to professional-, personal- and corporate ethics in client organisations was collated, and then used to develop a questionnaire. The questionnaires were distributed to internal and external stakeholders, who were involved during infrastructural delivery in client organisations, in order to acquire different views on ethical perceptions. The data obtained from the questionnaires were analysed, and used to test if the hypotheses were supported or not. Findings: The findings of this study revealed that the demographic profile does not have any significant influence on the ratings of internal and external stakeholders’ perceptions of the lack of professional and personal ethics – or on the enforcement of corporate ethics. Furthermore, this study also revealed that there is no significant difference in the ethical perceptions of internal and external stakeholders, on the enforcement of a professional and corporate ethical culture. Lastly, only in the personal ethics section there is a significant difference in ethical perception. In relation to the statement of the problem, the findings of this study revealed that internal and external stakeholders’ lack of professional- and personal ethics and the enforcement of corporate ethics are largely unknown. Research limitations: This study was limited to only Built environment professionals (including service providers) working for Eskom ECOU. Practical implications: The study revealed that there are ethical challenges in client organisations, even though they might be largely unknown. This clearly shows that construction industry professionals are all susceptible to unethical behaviour. Therefore, Eskom ECOU should refrain from only focusing on unethical behaviour by contractors and consulting firms; and it should also look at the client’s Built environment professionals; because there is evidence that they are also suspect during infrastructural delivery. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Information Technology, School of the Built Environment and Civil Engineering, 2021
- Full Text:
- Date Issued: 2015-01
- Authors: Dyariwe, Abongile
- Date: 2015-01
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53300 , vital:45131
- Description: Purpose of this treatise: This study is aimed at investigating whether there is a lack of professional- and, personal ethics, and a lack of enforcing corporate ethics from the Built environment professionals working for Eskom ECOU. Design/methodology/approach: The research approach used for the study was mainly quantitative. The quantitative methods used were descriptive and non-parametric statistical methods (Kruskal- Wallis Test and Mann-Whitney U Test). The selected sample for the study was categorised as internal stakeholders (i.e. employees that are permanently employed by Eskom) and external stakeholders (i.e. people that are employed by Eskom on a contract basis as quantity surveying, project management and engineering consultants) The scope of the study was to determine whether there are professional-, personal- and corporate ethical challenges in client organisations. A literature review was conducted; and all the relevant literature relating to professional-, personal- and corporate ethics in client organisations was collated, and then used to develop a questionnaire. The questionnaires were distributed to internal and external stakeholders, who were involved during infrastructural delivery in client organisations, in order to acquire different views on ethical perceptions. The data obtained from the questionnaires were analysed, and used to test if the hypotheses were supported or not. Findings: The findings of this study revealed that the demographic profile does not have any significant influence on the ratings of internal and external stakeholders’ perceptions of the lack of professional and personal ethics – or on the enforcement of corporate ethics. Furthermore, this study also revealed that there is no significant difference in the ethical perceptions of internal and external stakeholders, on the enforcement of a professional and corporate ethical culture. Lastly, only in the personal ethics section there is a significant difference in ethical perception. In relation to the statement of the problem, the findings of this study revealed that internal and external stakeholders’ lack of professional- and personal ethics and the enforcement of corporate ethics are largely unknown. Research limitations: This study was limited to only Built environment professionals (including service providers) working for Eskom ECOU. Practical implications: The study revealed that there are ethical challenges in client organisations, even though they might be largely unknown. This clearly shows that construction industry professionals are all susceptible to unethical behaviour. Therefore, Eskom ECOU should refrain from only focusing on unethical behaviour by contractors and consulting firms; and it should also look at the client’s Built environment professionals; because there is evidence that they are also suspect during infrastructural delivery. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Information Technology, School of the Built Environment and Civil Engineering, 2021
- Full Text:
- Date Issued: 2015-01
Neural network fault diagnosis system for a diesel-electric locomotive's closed loop excitation control system
- Authors: Barnard, Morne
- Date: 2017
- Subjects: Neural networks (Computer science) Diesel locomotives -- Motors -- Control systems
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/15955 , vital:28294
- Description: In closed loop control systems fault isolation is extremely difficult due to the fact that if feedbacks are corrupted or actuators can’t produce a desired output, a system reacts due to an increase in error between the measured variable and the set input variable, which can cause oscillations. The goal of this project is to develop a fault detection and isolation system for the isolation of faults, which cause oscillatory conditions on a GE Diesel-Electric Locomotive’s excitation control system. The proposed system will illustrate the use of artificial neural networks as a replacement to classical analytical models. The artificial neural network model’s design will be based on model-based dedicated observer theory to isolate sensor, as well as component faults, where observer theory will be utilised to effectively select input-output data configurations for detection of sensor and component faults causing oscillations. Owing to the nature of the locomotive’s data acquisition abilities, the model-based observer design will utilise historical data to design an effective model of the system which will be used to perform offline sampled fault detection. This method is proposed as an alternative to trend checking, data mining, etc. Faults are thus detected through the use of an offline model-based dedicated observer residual generator. With the use of a neural network a number of parameters affect the accuracy of the network where the primary source of ensuring an accurate model is training. The project highlights and experiments with these parameters to ensure an accurate model is trained with the use of the gradient descent training algorithm. The parameters which are considered are learning rate, hidden layer neurons, momentum and data preparation. The project will also provide a literature review on residual evaluation techniques used in practice and describe and evaluate the proposed method to perform residual evaluation for this specific application. The proposed method for residual evaluation was based on two principles, namely the moving average, as well as the simple thresholding techniques. The developed FDI system’s performance was measured against known faults and produced 100% accuracy for the detection and isolation of sensor and components causing oscillatory conditions on the locomotive’s excitation system.
- Full Text:
- Date Issued: 2017
- Authors: Barnard, Morne
- Date: 2017
- Subjects: Neural networks (Computer science) Diesel locomotives -- Motors -- Control systems
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/15955 , vital:28294
- Description: In closed loop control systems fault isolation is extremely difficult due to the fact that if feedbacks are corrupted or actuators can’t produce a desired output, a system reacts due to an increase in error between the measured variable and the set input variable, which can cause oscillations. The goal of this project is to develop a fault detection and isolation system for the isolation of faults, which cause oscillatory conditions on a GE Diesel-Electric Locomotive’s excitation control system. The proposed system will illustrate the use of artificial neural networks as a replacement to classical analytical models. The artificial neural network model’s design will be based on model-based dedicated observer theory to isolate sensor, as well as component faults, where observer theory will be utilised to effectively select input-output data configurations for detection of sensor and component faults causing oscillations. Owing to the nature of the locomotive’s data acquisition abilities, the model-based observer design will utilise historical data to design an effective model of the system which will be used to perform offline sampled fault detection. This method is proposed as an alternative to trend checking, data mining, etc. Faults are thus detected through the use of an offline model-based dedicated observer residual generator. With the use of a neural network a number of parameters affect the accuracy of the network where the primary source of ensuring an accurate model is training. The project highlights and experiments with these parameters to ensure an accurate model is trained with the use of the gradient descent training algorithm. The parameters which are considered are learning rate, hidden layer neurons, momentum and data preparation. The project will also provide a literature review on residual evaluation techniques used in practice and describe and evaluate the proposed method to perform residual evaluation for this specific application. The proposed method for residual evaluation was based on two principles, namely the moving average, as well as the simple thresholding techniques. The developed FDI system’s performance was measured against known faults and produced 100% accuracy for the detection and isolation of sensor and components causing oscillatory conditions on the locomotive’s excitation system.
- Full Text:
- Date Issued: 2017
Using agreements as an abstraction for access control administration
- Authors: Reyneke, André
- Date: 2007
- Subjects: Information -- control and access , Computer security -- Management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9791 , http://hdl.handle.net/10948/598 , http://hdl.handle.net/10948/d1011701 , Information -- control and access , Computer security -- Management
- Description: The last couple of decades saw lots of changes in the business world. Not only did technology change at a rapid pace, but businesses' views with respect to the role that information plays also changed drastically. Information is now seen as a strategic resource. This change paved the way for the so-called knowledge worker that not only consumes information, but actively participates in creating new knowledge from information. Employees must therefore be empowered to fulfill their new role as knowledge workers. Empowerment happens through job redefinition and by ensuring that the appropriate information is at hand. Although information is more readily available to employees, appropriate access controls must still be implemented. However, there is conflict between the need to share information and the need to keep information confidential. These conflicting needs must be reflected in the administration of access control. In order to resolve these conflicts, a finer granularity of access controls must be implemented. However, to implement a finer granularity of access control, an increase in the number of access controls and, therefore, the administrative burden is inevitable. Access control administrators must cater for a potentially large number of systems. These systems can not only be heterogenous as far as architecture and technology are concerned, but also with respect to access control paradigms. Vendors have realized that human involvement must be minimized, giving birth to so-called "provisioning systems". Provisioning systems, in principle, automate certain parts of access control administration. However, currently implementations are done in an ad hoc manner, that is, without a systematic process of identifying the real access control needs. This study aims to address this problem by proposing the "agreement abstraction" as a possible vehicle for systematically analyzing the access control requirements in a business. In essence, the agreement abstraction allows us to identify opportunities where access control can be automated. A specific methodological approach is suggested whereby the business is analysed in terms of business processes, as opposed to the more traditional resource perspective. Various business processes are used as examples to explain and motivate the proposed agreement abstraction further. This dissertation therefore contributes to the field of discourse by presenting a new abstraction that can be used systematically to analyse access control administration requirements.
- Full Text:
- Date Issued: 2007
- Authors: Reyneke, André
- Date: 2007
- Subjects: Information -- control and access , Computer security -- Management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9791 , http://hdl.handle.net/10948/598 , http://hdl.handle.net/10948/d1011701 , Information -- control and access , Computer security -- Management
- Description: The last couple of decades saw lots of changes in the business world. Not only did technology change at a rapid pace, but businesses' views with respect to the role that information plays also changed drastically. Information is now seen as a strategic resource. This change paved the way for the so-called knowledge worker that not only consumes information, but actively participates in creating new knowledge from information. Employees must therefore be empowered to fulfill their new role as knowledge workers. Empowerment happens through job redefinition and by ensuring that the appropriate information is at hand. Although information is more readily available to employees, appropriate access controls must still be implemented. However, there is conflict between the need to share information and the need to keep information confidential. These conflicting needs must be reflected in the administration of access control. In order to resolve these conflicts, a finer granularity of access controls must be implemented. However, to implement a finer granularity of access control, an increase in the number of access controls and, therefore, the administrative burden is inevitable. Access control administrators must cater for a potentially large number of systems. These systems can not only be heterogenous as far as architecture and technology are concerned, but also with respect to access control paradigms. Vendors have realized that human involvement must be minimized, giving birth to so-called "provisioning systems". Provisioning systems, in principle, automate certain parts of access control administration. However, currently implementations are done in an ad hoc manner, that is, without a systematic process of identifying the real access control needs. This study aims to address this problem by proposing the "agreement abstraction" as a possible vehicle for systematically analyzing the access control requirements in a business. In essence, the agreement abstraction allows us to identify opportunities where access control can be automated. A specific methodological approach is suggested whereby the business is analysed in terms of business processes, as opposed to the more traditional resource perspective. Various business processes are used as examples to explain and motivate the proposed agreement abstraction further. This dissertation therefore contributes to the field of discourse by presenting a new abstraction that can be used systematically to analyse access control administration requirements.
- Full Text:
- Date Issued: 2007
Modelling the intention to change Facebook privacy settings on mobile phones
- Authors: Miya, Asanda Christopher
- Date: 2017
- Subjects: Online social networks -- Security measures Cell phone systems
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/19531 , vital:28890
- Description: Facebook and other social networking services have significantly changed the way people communicate and share information on the Internet. People are increasingly accessing these networking services on mobile phones as opposed to traditional computers. While privacy in social networking services always was a concern, mobile phones make it even easier to share personal information, thus spotlighting privacy concerns. Facebook has privacy settings for the users who use the service on various mobile phones. However, the failure of Facebook users to change privacy settings on mobile phones may result in undesirable sharing of personal information thereby exposing the users to privacy threats. This study extends the understanding of the use of Facebook privacy settings by investigating what impacts the intention to change the privacy settings on mobile phones. The Theory of Planned Behaviour (TPB) is identified as a theoretical underpinning that relates to the intention to perform a behaviour. Structural equation modelling is chosen as a suitable research method. A conceptual model is theorized by building on the Theory of Planned Behaviour. Following suggestions by other studies, the Perceived Behavioural Control (PBC) construct are speci_cally deconstructed into internal and external factors. Nine hypotheses are predicted. A measurement instrument in the form of a questionnaire consisting of 43 items is developed. The conceptual model is evaluated using empirical data, which is gathered from a sample of 414 South African Facebook users. The evaluation of the conceptual model shows it to be a good fit. Out of the nine hypotheses, five are accepted for the final model of the study. Self-efficacy are found to be a positive internal factor that inuences user's perceived control of changing Facebook privacy settings on mobile phones. Facilitating conditions and Perceived Required effort are found to be external factors that respectively have a positive and negative inuence on user's Perceived Behavioural Control. Attitude and Perceived Behavioural Control are both found to have a positive inuence on user's intention to change Facebook privacy settings on mobile phones. The hypotheses that could not be accepted are discussed and it is argued that potential unintended bias in the sample may have had an inuence. More detailed investigation are left for future studies.
- Full Text:
- Date Issued: 2017
- Authors: Miya, Asanda Christopher
- Date: 2017
- Subjects: Online social networks -- Security measures Cell phone systems
- Language: English
- Type: Thesis , Masters , MIT
- Identifier: http://hdl.handle.net/10948/19531 , vital:28890
- Description: Facebook and other social networking services have significantly changed the way people communicate and share information on the Internet. People are increasingly accessing these networking services on mobile phones as opposed to traditional computers. While privacy in social networking services always was a concern, mobile phones make it even easier to share personal information, thus spotlighting privacy concerns. Facebook has privacy settings for the users who use the service on various mobile phones. However, the failure of Facebook users to change privacy settings on mobile phones may result in undesirable sharing of personal information thereby exposing the users to privacy threats. This study extends the understanding of the use of Facebook privacy settings by investigating what impacts the intention to change the privacy settings on mobile phones. The Theory of Planned Behaviour (TPB) is identified as a theoretical underpinning that relates to the intention to perform a behaviour. Structural equation modelling is chosen as a suitable research method. A conceptual model is theorized by building on the Theory of Planned Behaviour. Following suggestions by other studies, the Perceived Behavioural Control (PBC) construct are speci_cally deconstructed into internal and external factors. Nine hypotheses are predicted. A measurement instrument in the form of a questionnaire consisting of 43 items is developed. The conceptual model is evaluated using empirical data, which is gathered from a sample of 414 South African Facebook users. The evaluation of the conceptual model shows it to be a good fit. Out of the nine hypotheses, five are accepted for the final model of the study. Self-efficacy are found to be a positive internal factor that inuences user's perceived control of changing Facebook privacy settings on mobile phones. Facilitating conditions and Perceived Required effort are found to be external factors that respectively have a positive and negative inuence on user's Perceived Behavioural Control. Attitude and Perceived Behavioural Control are both found to have a positive inuence on user's intention to change Facebook privacy settings on mobile phones. The hypotheses that could not be accepted are discussed and it is argued that potential unintended bias in the sample may have had an inuence. More detailed investigation are left for future studies.
- Full Text:
- Date Issued: 2017
Improving decision making through analysing the economic impact of budget allocation at the city of Cape Town
- Authors: Kaiser, Gisela Noelle
- Date: 2013
- Subjects: Cape Town (South Africa) -- Politics and government , City planning -- South Africa --Cape Town , Budget -- South Africa -- Cape Town , Local government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9684 , http://hdl.handle.net/10948/d1008305 , Cape Town (South Africa) -- Politics and government , City planning -- South Africa --Cape Town , Budget -- South Africa -- Cape Town , Local government
- Description: Local government is at the forefront of engagement between the government and South Africa’s people, delivering basic services to communities. Following the transition to a democratic government in 1994, the country was demarcated in a manner that provides complete coverage by local government. Annually, managing the administration of service delivery implementation at local government level costs the country many billions. Much of the revenue used by local government in providing services is derived from income from sale of basic services and property rates, augmented by allocations from national and provincial government, equitably shared amongst municipalities. Local government has autonomy in its operations, but is strictly governed by a collection of cascading legislation, introduced to protect the interests of the people. The primary objective of the research was to investigate the efficacy of budget expenditure in local government, in particular the City of Cape Town as a metropolitan municipality. With an annual budget approaching R30 billion, the aim was to establish how the budget was determined and allocated to the service menu provided by the City, and to investigate whether better methods of allocating expenditure could be developed. A mixed research methodology was followed, relying on quantitative methods for analysing survey data statistically, while providing for detailed qualitative methods in interviewing and studying the specific case in detail. The theoretical perspective most suited to this research was found to be that of pragmatism, for its flexibility of interpretation, practicality and space for multiple perspectives. A constructivist epistemology was adopted to provide for the interplay between object and subject in constructing meaning. This research focused on examination of applicable legislation, secondary data in reports, and statistical analysis of opinion surveys of municipal officials involved in budgeting at different levels and interviews with key stakeholders. The findings indicate that budget allocation can be improved upon in a number of ways, despite complying with a myriad of restrictive and onerous regulations applicable to local government. It was found that the administration is fragmented in its operations and that the structure of necessity favours isolated service delivery rather than integration. Further, that compliance impacts negatively on time spent in planning and pursuit of strategic intent to the extent that Reporting often becomes a more important deliverable than basic services. The size of the City hinders common understanding, and introducing any change in political vision requires particular attention.
- Full Text:
- Date Issued: 2013
- Authors: Kaiser, Gisela Noelle
- Date: 2013
- Subjects: Cape Town (South Africa) -- Politics and government , City planning -- South Africa --Cape Town , Budget -- South Africa -- Cape Town , Local government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9684 , http://hdl.handle.net/10948/d1008305 , Cape Town (South Africa) -- Politics and government , City planning -- South Africa --Cape Town , Budget -- South Africa -- Cape Town , Local government
- Description: Local government is at the forefront of engagement between the government and South Africa’s people, delivering basic services to communities. Following the transition to a democratic government in 1994, the country was demarcated in a manner that provides complete coverage by local government. Annually, managing the administration of service delivery implementation at local government level costs the country many billions. Much of the revenue used by local government in providing services is derived from income from sale of basic services and property rates, augmented by allocations from national and provincial government, equitably shared amongst municipalities. Local government has autonomy in its operations, but is strictly governed by a collection of cascading legislation, introduced to protect the interests of the people. The primary objective of the research was to investigate the efficacy of budget expenditure in local government, in particular the City of Cape Town as a metropolitan municipality. With an annual budget approaching R30 billion, the aim was to establish how the budget was determined and allocated to the service menu provided by the City, and to investigate whether better methods of allocating expenditure could be developed. A mixed research methodology was followed, relying on quantitative methods for analysing survey data statistically, while providing for detailed qualitative methods in interviewing and studying the specific case in detail. The theoretical perspective most suited to this research was found to be that of pragmatism, for its flexibility of interpretation, practicality and space for multiple perspectives. A constructivist epistemology was adopted to provide for the interplay between object and subject in constructing meaning. This research focused on examination of applicable legislation, secondary data in reports, and statistical analysis of opinion surveys of municipal officials involved in budgeting at different levels and interviews with key stakeholders. The findings indicate that budget allocation can be improved upon in a number of ways, despite complying with a myriad of restrictive and onerous regulations applicable to local government. It was found that the administration is fragmented in its operations and that the structure of necessity favours isolated service delivery rather than integration. Further, that compliance impacts negatively on time spent in planning and pursuit of strategic intent to the extent that Reporting often becomes a more important deliverable than basic services. The size of the City hinders common understanding, and introducing any change in political vision requires particular attention.
- Full Text:
- Date Issued: 2013
Mitigation of single event upsets in a XILINX ARTIX-7 field programmable gate array
- Authors: Omolo, Joshua
- Date: 2018
- Subjects: Field programmable gate arrays -- Design and construction Prototypes, Engineering
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/22310 , vital:29942
- Description: Field programmable gate arrays are increasingly being used in harsh environments like space where high energy particles from radiation affect the integrity of the data. Before deployment of satellites in space, characterisation and consequently mitigation of radiation effects is necessary to avoid failure. By irradiating a digital microelectronic device, using accelerated energetic particles, it is possible to predict the likelihood of an event effect happening. Such irradiation tests can only be done at a particle accelerator facility such as iThemba LABS in Cape Town. It is the one of the few particle accelerators in the southern hemisphere and offers the capacity to perform these event effect characterisation tests. Triple Modular Redundancy (TMR) is a commonly used mitigation technique in microelectronics. Although effective, it has the downside of increased resource area. A DMR-Filter combination mitigation technique was developed at the Nelson Mandela University. It uses fewer resources than TMR and it is envisaged to significantly reduce event upsets in a FPGA. This research project seeks to investigate the effectiveness of the DMR-Filter combination mitigation technique in reducing the likelihood of event upsets occurring in Xilinx’s Artix-7 FPGA when exposed to highly accelerated particles, similar to those in space.
- Full Text:
- Date Issued: 2018
- Authors: Omolo, Joshua
- Date: 2018
- Subjects: Field programmable gate arrays -- Design and construction Prototypes, Engineering
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/22310 , vital:29942
- Description: Field programmable gate arrays are increasingly being used in harsh environments like space where high energy particles from radiation affect the integrity of the data. Before deployment of satellites in space, characterisation and consequently mitigation of radiation effects is necessary to avoid failure. By irradiating a digital microelectronic device, using accelerated energetic particles, it is possible to predict the likelihood of an event effect happening. Such irradiation tests can only be done at a particle accelerator facility such as iThemba LABS in Cape Town. It is the one of the few particle accelerators in the southern hemisphere and offers the capacity to perform these event effect characterisation tests. Triple Modular Redundancy (TMR) is a commonly used mitigation technique in microelectronics. Although effective, it has the downside of increased resource area. A DMR-Filter combination mitigation technique was developed at the Nelson Mandela University. It uses fewer resources than TMR and it is envisaged to significantly reduce event upsets in a FPGA. This research project seeks to investigate the effectiveness of the DMR-Filter combination mitigation technique in reducing the likelihood of event upsets occurring in Xilinx’s Artix-7 FPGA when exposed to highly accelerated particles, similar to those in space.
- Full Text:
- Date Issued: 2018
A cyber security awareness and education framework for South Africa
- Authors: Kortjan, Noloxolo
- Date: 2013
- Subjects: Computer networks -- Security measures , Computer crimes -- Prevention , Computer security
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9811 , http://hdl.handle.net/10948/d1014829
- Description: The Internet is becoming increasingly interwoven in the daily life of many individuals, organisations and nations. It has, to a large extent, had a positive effect on the way people communicate. It has also introduced new avenues for business and has offered nations an opportunity to govern online. Nevertheless, although cyberspace offers an endless list of services and opportunities, it is also accompanied by many risks. One of these risks is cybercrime. The Internet has given criminals a platform on which to grow and proliferate. As a result of the abstract nature of the Internet, it is easy for these criminals to go unpunished. Moreover, many who use the Internet are not aware of such threats; therefore they may themselves be at risk, together with businesses and governmental assets and infrastructure. In view of this, there is a need for cyber security awareness and education initiatives that will promote users who are well versed in the risks associated with the Internet. In this context, it is the role of the government to empower all levels of society by providing the necessary knowledge and expertise to act securely online. However, there is currently a definite lack in South Africa (SA) in this regard, as there are currently no government-led cyber security awareness and education initiatives. The primary research objective of this study, therefore, is to propose a cyber security awareness and education framework for SA that will assist in creating a cyber secure culture in SA among all of its users of the Internet.
- Full Text:
- Date Issued: 2013
- Authors: Kortjan, Noloxolo
- Date: 2013
- Subjects: Computer networks -- Security measures , Computer crimes -- Prevention , Computer security
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9811 , http://hdl.handle.net/10948/d1014829
- Description: The Internet is becoming increasingly interwoven in the daily life of many individuals, organisations and nations. It has, to a large extent, had a positive effect on the way people communicate. It has also introduced new avenues for business and has offered nations an opportunity to govern online. Nevertheless, although cyberspace offers an endless list of services and opportunities, it is also accompanied by many risks. One of these risks is cybercrime. The Internet has given criminals a platform on which to grow and proliferate. As a result of the abstract nature of the Internet, it is easy for these criminals to go unpunished. Moreover, many who use the Internet are not aware of such threats; therefore they may themselves be at risk, together with businesses and governmental assets and infrastructure. In view of this, there is a need for cyber security awareness and education initiatives that will promote users who are well versed in the risks associated with the Internet. In this context, it is the role of the government to empower all levels of society by providing the necessary knowledge and expertise to act securely online. However, there is currently a definite lack in South Africa (SA) in this regard, as there are currently no government-led cyber security awareness and education initiatives. The primary research objective of this study, therefore, is to propose a cyber security awareness and education framework for SA that will assist in creating a cyber secure culture in SA among all of its users of the Internet.
- Full Text:
- Date Issued: 2013
Single event upset testing of flash based field programmable gate arrays
- Authors: Potgieter, Juan-Pierre
- Date: 2015
- Subjects: Field programmable gate arrays
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/12520 , vital:27083
- Description: In the last 50 years microelectronics have advanced at an exponential rate, causing microelectronic devices to shrink, have very low operating voltages and increased complexities; all this has made circuits more sensitive to various kinds of failures. These trends allowed soft errors, which up until recently was just a concern for space application, to become a major source of system failures of electronic products. The aim of this research paper was to investigate different mitigation techniques that prevent these soft errors in a Video Graphics Array (VGA) controller which is commonly used in projecting images captured by cameras. This controller was implemented on a Flash Based Field Programmable Gate array (FPGA). A test set-up was designed and implemented at NRF iThemba LABS, which was used to conduct the experiments necessary to evaluate the effectiveness of different mitigation techniques. The set-up was capable of handling multiple Device Under Tests (DUT) and had the ability to change the angle of incidence of each DUT. The DUTs were radiated with a 66MeV proton beam while the monitoring equipment observed any errors that had occurred. The results obtained indicated that all the implemented mitigation techniques tested on the VGA system improved the system’s capability of mitigating Single Event Upsets (SEU). The most effective mitigation technique was the OR-AND Multiplexer Single Event Transient (SET) filter technique. It was thus shown that mitigation techniques are viable options to prevent SEU in a VGA controller. The permanent SEU testing set-up which was designed and manufactured and was used to conduct the experiments, proved to be a practical option for further microelectronics testing at iThemba LABS.
- Full Text:
- Date Issued: 2015
- Authors: Potgieter, Juan-Pierre
- Date: 2015
- Subjects: Field programmable gate arrays
- Language: English
- Type: Thesis , Masters , MEngineering
- Identifier: http://hdl.handle.net/10948/12520 , vital:27083
- Description: In the last 50 years microelectronics have advanced at an exponential rate, causing microelectronic devices to shrink, have very low operating voltages and increased complexities; all this has made circuits more sensitive to various kinds of failures. These trends allowed soft errors, which up until recently was just a concern for space application, to become a major source of system failures of electronic products. The aim of this research paper was to investigate different mitigation techniques that prevent these soft errors in a Video Graphics Array (VGA) controller which is commonly used in projecting images captured by cameras. This controller was implemented on a Flash Based Field Programmable Gate array (FPGA). A test set-up was designed and implemented at NRF iThemba LABS, which was used to conduct the experiments necessary to evaluate the effectiveness of different mitigation techniques. The set-up was capable of handling multiple Device Under Tests (DUT) and had the ability to change the angle of incidence of each DUT. The DUTs were radiated with a 66MeV proton beam while the monitoring equipment observed any errors that had occurred. The results obtained indicated that all the implemented mitigation techniques tested on the VGA system improved the system’s capability of mitigating Single Event Upsets (SEU). The most effective mitigation technique was the OR-AND Multiplexer Single Event Transient (SET) filter technique. It was thus shown that mitigation techniques are viable options to prevent SEU in a VGA controller. The permanent SEU testing set-up which was designed and manufactured and was used to conduct the experiments, proved to be a practical option for further microelectronics testing at iThemba LABS.
- Full Text:
- Date Issued: 2015
A holistic approach to network security in OGSA-based grid systems
- Authors: Loutsios, Demetrios
- Date: 2006
- Subjects: Computer networks -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9736 , http://hdl.handle.net/10948/550 , Computer networks -- Security measures
- Description: Grid computing technologies facilitate complex scientific collaborations between globally dispersed parties, which make use of heterogeneous technologies and computing systems. However, in recent years the commercial sector has developed a growing interest in Grid technologies. Prominent Grid researchers have predicted Grids will grow into the commercial mainstream, even though its origins were in scientific research. This is much the same way as the Internet started as a vehicle for research collaboration between universities and government institutions, and grew into a technology with large commercial applications. Grids facilitate complex trust relationships between globally dispersed business partners, research groups, and non-profit organizations. Almost any dispersed “virtual organization” willing to share computing resources can make use of Grid technologies. Grid computing facilitates the networking of shared services; the inter-connection of a potentially unlimited number of computing resources within a “Grid” is possible. Grid technologies leverage a range of open standards and technologies to provide interoperability between heterogeneous computing systems. Newer Grids build on key capabilities of Web-Service technologies to provide easy and dynamic publishing and discovery of Grid resources. Due to the inter-organisational nature of Grid systems, there is a need to provide adequate security to Grid users and to Grid resources. This research proposes a framework, using a specific brokered pattern, which addresses several common Grid security challenges, which include: Providing secure and consistent cross-site Authentication and Authorization; Single-sign on capabilities to Grid users; Abstract iii; Underlying platform and runtime security, and; Grid network communications and messaging security. These Grid security challenges can be viewed as comprising two (proposed) logical layers of a Grid. These layers are: a Common Grid Layer (higher level Grid interactions), and a Local Resource Layer (Lower level technology security concerns). This research is concerned with providing a generic and holistic security framework to secure both layers. This research makes extensive use of STRIDE - an acronym for Microsoft approach to addressing security threats - as part of a holistic Grid security framework. STRIDE and key Grid related standards, such as Open Grid Service Architecture (OGSA), Web-Service Resource Framework (WS-RF), and the Globus Toolkit are used to formulate the proposed framework.
- Full Text:
- Date Issued: 2006
- Authors: Loutsios, Demetrios
- Date: 2006
- Subjects: Computer networks -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9736 , http://hdl.handle.net/10948/550 , Computer networks -- Security measures
- Description: Grid computing technologies facilitate complex scientific collaborations between globally dispersed parties, which make use of heterogeneous technologies and computing systems. However, in recent years the commercial sector has developed a growing interest in Grid technologies. Prominent Grid researchers have predicted Grids will grow into the commercial mainstream, even though its origins were in scientific research. This is much the same way as the Internet started as a vehicle for research collaboration between universities and government institutions, and grew into a technology with large commercial applications. Grids facilitate complex trust relationships between globally dispersed business partners, research groups, and non-profit organizations. Almost any dispersed “virtual organization” willing to share computing resources can make use of Grid technologies. Grid computing facilitates the networking of shared services; the inter-connection of a potentially unlimited number of computing resources within a “Grid” is possible. Grid technologies leverage a range of open standards and technologies to provide interoperability between heterogeneous computing systems. Newer Grids build on key capabilities of Web-Service technologies to provide easy and dynamic publishing and discovery of Grid resources. Due to the inter-organisational nature of Grid systems, there is a need to provide adequate security to Grid users and to Grid resources. This research proposes a framework, using a specific brokered pattern, which addresses several common Grid security challenges, which include: Providing secure and consistent cross-site Authentication and Authorization; Single-sign on capabilities to Grid users; Abstract iii; Underlying platform and runtime security, and; Grid network communications and messaging security. These Grid security challenges can be viewed as comprising two (proposed) logical layers of a Grid. These layers are: a Common Grid Layer (higher level Grid interactions), and a Local Resource Layer (Lower level technology security concerns). This research is concerned with providing a generic and holistic security framework to secure both layers. This research makes extensive use of STRIDE - an acronym for Microsoft approach to addressing security threats - as part of a holistic Grid security framework. STRIDE and key Grid related standards, such as Open Grid Service Architecture (OGSA), Web-Service Resource Framework (WS-RF), and the Globus Toolkit are used to formulate the proposed framework.
- Full Text:
- Date Issued: 2006
Friction hydro pillar riveting process of Ti-6AI-4V titanium sheet
- Authors: Tsikayi, Davies Shamiso
- Date: 2015
- Subjects: Friction welding , Titanium alloys -- Welding , Sheet-metal
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/6357 , vital:21078
- Description: Mechanical fasteners are used extensively in the joining of two or more metal plates or sheets. Riveted joints have been the joints of choice mainly for the Aerospace Industry. However for this research, Friction Hydro Pillar Processing has been used to develop and characterise a new riveting technique termed Friction Hydro Pillar Riveting (FHPR). Two overlapping 3.17 mm Ti-6Al-4V sheets were joined together using Ø6 mm rivet which was friction processed. This research has focussed on the initial development of Friction Hydro Pillar Riveting thereby establishing a basic understanding of the influences of main process parameters, rotational speed and axial force - and also joint configurations. The results showed that with a decrease in the bottom hole chamfer angle, there was resulting overall increase in the rivet joint pull off strength. From the best performing joint configuration in pull off tests, shear tests were conducted whilst a blind hole FHPR joint was also done and tested in pull off and shear strength. The shear test fracture surfaces exhibited ductile failure. The microstructure of the joints was thus evaluated. From parent material, heat affected zone and to weld zone there was a variation in the microstructure analysed. The hardness profiles showed increased hardness in the weld zone which partly explained the shear results. The hardness increase was mainly due to grain refinement in the weld zone by the Friction Hydro Pillar Riveting process.
- Full Text:
- Date Issued: 2015
- Authors: Tsikayi, Davies Shamiso
- Date: 2015
- Subjects: Friction welding , Titanium alloys -- Welding , Sheet-metal
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/6357 , vital:21078
- Description: Mechanical fasteners are used extensively in the joining of two or more metal plates or sheets. Riveted joints have been the joints of choice mainly for the Aerospace Industry. However for this research, Friction Hydro Pillar Processing has been used to develop and characterise a new riveting technique termed Friction Hydro Pillar Riveting (FHPR). Two overlapping 3.17 mm Ti-6Al-4V sheets were joined together using Ø6 mm rivet which was friction processed. This research has focussed on the initial development of Friction Hydro Pillar Riveting thereby establishing a basic understanding of the influences of main process parameters, rotational speed and axial force - and also joint configurations. The results showed that with a decrease in the bottom hole chamfer angle, there was resulting overall increase in the rivet joint pull off strength. From the best performing joint configuration in pull off tests, shear tests were conducted whilst a blind hole FHPR joint was also done and tested in pull off and shear strength. The shear test fracture surfaces exhibited ductile failure. The microstructure of the joints was thus evaluated. From parent material, heat affected zone and to weld zone there was a variation in the microstructure analysed. The hardness profiles showed increased hardness in the weld zone which partly explained the shear results. The hardness increase was mainly due to grain refinement in the weld zone by the Friction Hydro Pillar Riveting process.
- Full Text:
- Date Issued: 2015
Characterising the structural integrity of mechanical formed low carbon steel
- Authors: Victor, Ngea Njoume
- Date: 2012
- Subjects: Carbon steel , Structural analysis (Engineering) , Steel, Structural
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9627 , http://hdl.handle.net/10948/d1012089 , Carbon steel , Structural analysis (Engineering) , Steel, Structural
- Description: The contribution of the clamping force in the technique used in this study to stretch-bend low carbon steel samples was investigated to support the subsequent changes in the microstructure and properties of the formed material with regard to parent material. Although plastic deformation by cold working is known to induce texture or preferred orientation to the grains of a formed material while decreasing its ductility and increasing the strength, as well as inducing residual stress, it is not known how the different directions (rolling, transverse and oblique/45°) of the sheet steel will respond to this stretch bending technique. The first part of the research work involved a thorough literature review on sheet metal forming processes and their effect on the formed material with interest on the above mentioned directions of the sheet. It became clear from the literature overview that cold working of a material will induce strain-hardening which varies with the magnitude of cold work, resulting in changes in the strength and ductility of the material. Besides, when plastic deformation is not uniform (e.g., tensile and compressive) throughout the entire cross section of the formed part, residual stresses remain in the material with the grains been elongated along the direction of the maximum strain. The main parameters that were considered and controlled in this study are as follows: strain experienced / stress induced into the form sample, the sample direction, the stroke length and the clamping torque, the generated radius of curvature. The chapters that follow the literature review, deal with the set-up of the different equipment used in this study, the specimen preparation as well as the recording, the calculation and interpretation of the results. It was found that the stress magnitude that generated the different radii of curvature (120 mm, 150 mm and 185 mm) was between 1 percent & 13 percent higher than the parent material’s yield strength with the lower stress been associated to the smaller radius of curvature and the higher stress to the higher radius. The stress induced into the sample during forming was not only proportional to the stroke length but also to the distance between the punch’s tip and the sample and the sample to the die’s nadir. The clamping torque adopted was restricted to the manual capacity of the operator who used a preset torque wrench to fasten the plate sample into the jig. Plate samples of low carbon steel were cut to angles of 0°, 45°, and 90° to the rolling direction of the sheet material and stretch-bent on a single-action mechanical press to 120 mm, 150 mm, and 185 mm radii of curvature. The preliminary results indicate that stretch-bent samples had increased hardness to the parent plate, in particular below the surface layers up to around 1.1 mm depth. Since there is a well established relationship between hardness, yield and tensile strengths for steel, the yield and tensile strengths of the formed material were estimated using the Nobre et al [34] incremental relation, which relates the linearity between relative increments of hardness and yield strength. Changes were not noticeable at the microstructural level of the formed samples. Meanwhile, samples from which higher plastic deformation stress values were calculated were not those absorbing higher impact energy when Charpy specimen cut from plate and stretch-bent samples were tested. The maximum relieved residual stress in the parent material was predominantly compressive and represents in magnitude approximately 12 percent (average for the three directions) of its original yield strength. In the stretch-bent samples, the relieved residual stress was compressive in the outer curved section with a magnitude about 50 percent of the parent material yield strength and tensile in the inner curved section with a magnitude approximately 25 percent of the parent material yield strength.
- Full Text:
- Date Issued: 2012
- Authors: Victor, Ngea Njoume
- Date: 2012
- Subjects: Carbon steel , Structural analysis (Engineering) , Steel, Structural
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9627 , http://hdl.handle.net/10948/d1012089 , Carbon steel , Structural analysis (Engineering) , Steel, Structural
- Description: The contribution of the clamping force in the technique used in this study to stretch-bend low carbon steel samples was investigated to support the subsequent changes in the microstructure and properties of the formed material with regard to parent material. Although plastic deformation by cold working is known to induce texture or preferred orientation to the grains of a formed material while decreasing its ductility and increasing the strength, as well as inducing residual stress, it is not known how the different directions (rolling, transverse and oblique/45°) of the sheet steel will respond to this stretch bending technique. The first part of the research work involved a thorough literature review on sheet metal forming processes and their effect on the formed material with interest on the above mentioned directions of the sheet. It became clear from the literature overview that cold working of a material will induce strain-hardening which varies with the magnitude of cold work, resulting in changes in the strength and ductility of the material. Besides, when plastic deformation is not uniform (e.g., tensile and compressive) throughout the entire cross section of the formed part, residual stresses remain in the material with the grains been elongated along the direction of the maximum strain. The main parameters that were considered and controlled in this study are as follows: strain experienced / stress induced into the form sample, the sample direction, the stroke length and the clamping torque, the generated radius of curvature. The chapters that follow the literature review, deal with the set-up of the different equipment used in this study, the specimen preparation as well as the recording, the calculation and interpretation of the results. It was found that the stress magnitude that generated the different radii of curvature (120 mm, 150 mm and 185 mm) was between 1 percent & 13 percent higher than the parent material’s yield strength with the lower stress been associated to the smaller radius of curvature and the higher stress to the higher radius. The stress induced into the sample during forming was not only proportional to the stroke length but also to the distance between the punch’s tip and the sample and the sample to the die’s nadir. The clamping torque adopted was restricted to the manual capacity of the operator who used a preset torque wrench to fasten the plate sample into the jig. Plate samples of low carbon steel were cut to angles of 0°, 45°, and 90° to the rolling direction of the sheet material and stretch-bent on a single-action mechanical press to 120 mm, 150 mm, and 185 mm radii of curvature. The preliminary results indicate that stretch-bent samples had increased hardness to the parent plate, in particular below the surface layers up to around 1.1 mm depth. Since there is a well established relationship between hardness, yield and tensile strengths for steel, the yield and tensile strengths of the formed material were estimated using the Nobre et al [34] incremental relation, which relates the linearity between relative increments of hardness and yield strength. Changes were not noticeable at the microstructural level of the formed samples. Meanwhile, samples from which higher plastic deformation stress values were calculated were not those absorbing higher impact energy when Charpy specimen cut from plate and stretch-bent samples were tested. The maximum relieved residual stress in the parent material was predominantly compressive and represents in magnitude approximately 12 percent (average for the three directions) of its original yield strength. In the stretch-bent samples, the relieved residual stress was compressive in the outer curved section with a magnitude about 50 percent of the parent material yield strength and tensile in the inner curved section with a magnitude approximately 25 percent of the parent material yield strength.
- Full Text:
- Date Issued: 2012
A sustainable water quality framework for South Africa towards 2050
- Authors: Osmond, Christopher John
- Date: 2015
- Subjects: Construction industry -- South Africa , Sustainable development -- South Africa , Water resources development -- South Africa , Water quality management -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3255 , vital:20417
- Description: There are a wide range of issues that stem from inadequate access to, and the unsustainable management of water resources, which can lead to ecological and human crises (Gleik, 1998: 571). With the increasing demand for clean water for drinking and sanitation, coupled with population growth, aging infrastructure, and climate change, many countries face a complex set of threats when dealing with their water resources and the management thereof (Environmental Protection Agency, 2012: 4). South Africa‟s challenges are no different, if current trends in water management continue and government does not intervene with what has been an unequal society even in terms of the division of water, it will continue to lose ground in its development and sustaining of water resources (Ukwandu, 2009: 24 - 30). “The objective of managing the quantity, quality and reliability of the nation‟s water resources is to achieve optimum, long-term, environmentally sustainable social and economic benefit for society from their use.” (Principle 7 of the National Water Policy, Department of Water Affairs and Forestry, 1997: 20). The primary objective of this research is to develop a framework for water management and sustainable development by utilising a Causal Layered Analysis (CLA) to develop strategies for innovation in South Africa towards 2050. New rules and regulations have been adopted by local municipal divisions in South Africa to promote sustainable, environmentally friendly buildings and methods. It is therefore the aim of the research to establish ways in which water can be harvested and saved in a simple and innovative yet sustainable manner. The complexity of erecting structures has also increased with some sustainable measures in water management taking place, however the water issues in South Africa continue to grow and cause concern. Government therefore plays a pivotal role in ensuring that water is managed sustainably at not only harvesting and infrastructure level but also re-cycling level, where simple innovative strategies can be adopted. This paper further seeks to highlight the positive and negative impacts of implementing water management methods and strategies that can be adopted.
- Full Text:
- Date Issued: 2015
- Authors: Osmond, Christopher John
- Date: 2015
- Subjects: Construction industry -- South Africa , Sustainable development -- South Africa , Water resources development -- South Africa , Water quality management -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3255 , vital:20417
- Description: There are a wide range of issues that stem from inadequate access to, and the unsustainable management of water resources, which can lead to ecological and human crises (Gleik, 1998: 571). With the increasing demand for clean water for drinking and sanitation, coupled with population growth, aging infrastructure, and climate change, many countries face a complex set of threats when dealing with their water resources and the management thereof (Environmental Protection Agency, 2012: 4). South Africa‟s challenges are no different, if current trends in water management continue and government does not intervene with what has been an unequal society even in terms of the division of water, it will continue to lose ground in its development and sustaining of water resources (Ukwandu, 2009: 24 - 30). “The objective of managing the quantity, quality and reliability of the nation‟s water resources is to achieve optimum, long-term, environmentally sustainable social and economic benefit for society from their use.” (Principle 7 of the National Water Policy, Department of Water Affairs and Forestry, 1997: 20). The primary objective of this research is to develop a framework for water management and sustainable development by utilising a Causal Layered Analysis (CLA) to develop strategies for innovation in South Africa towards 2050. New rules and regulations have been adopted by local municipal divisions in South Africa to promote sustainable, environmentally friendly buildings and methods. It is therefore the aim of the research to establish ways in which water can be harvested and saved in a simple and innovative yet sustainable manner. The complexity of erecting structures has also increased with some sustainable measures in water management taking place, however the water issues in South Africa continue to grow and cause concern. Government therefore plays a pivotal role in ensuring that water is managed sustainably at not only harvesting and infrastructure level but also re-cycling level, where simple innovative strategies can be adopted. This paper further seeks to highlight the positive and negative impacts of implementing water management methods and strategies that can be adopted.
- Full Text:
- Date Issued: 2015
Analysis of fuel consumption reduction potential through the use of an electrically driven air conditioning compressor
- Authors: Marais, Charel
- Date: 2007
- Subjects: Automobiles -- Air conditioning , Electric vehicles -- Power supply , Automobiles -- Fuel systems , Electric automobiles
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9623 , http://hdl.handle.net/10948/774 , Automobiles -- Air conditioning , Electric vehicles -- Power supply , Automobiles -- Fuel systems , Electric automobiles
- Description: The disturbing current situation regarding the world climate has initiated a major wave of urgent developments towards decreasing the overall impact of human activities on the living environment. A major role player in this development is the automobile industry that is inherently connected to pollution of various types, be it air, water or noise pollution. There have been drastic changes not only in the technologies employed in producing vehicles and components, but also in the construction and technologies built into modern automobiles to lessen the overall environmental impact of the industry. Noxious emissions have been decreased, overall efficiencies increased and vehicles are becoming more economical with each new generation. Stricter laws dictate that the level of acceptable vehicle emissions is to be decreased ever further and all manufacturers are developing various possibilities to achieve this. With the emergence of hybrid vehicle technology, there was also a sudden development of different electrical systems that were made viable by the higher onboard voltage systems employed in hybrid vehicles. One of these developments was the electrical air conditioning compressor for use in automobile applications. Although it is designed to operate with a higher voltage than the traditional 12V onboard vehicle systems, it is theoretically possible to incorporate it into a 12V system by making use of a DC-DC converter to step up the supply voltage of the electrical compressor sufficiently to allow for its successful operation. The question therefore arises whether it would be feasible and sensible to employ an electrical air conditioning system in conventional combustion engine vehicles from an overall fuel consumption and vehicle emissions point of view. A modelling approach was taken where an overall vehicle driving simulation was created to represent an average modern production vehicle. The simulation was then extended to include the options of incorporating models for both mechanically and electrically driven air conditioning systems. This provides insight into the influences of the air conditioning system on the vehicle’s overall fuel consumption and an opportunity to compare the influences from the two different systems. This study attempted to provide answers to some of the viability questions regarding the incorporation of electrically driven air conditioning systems into vehicles that use standard 12V onboard voltage systems. It was found that the electrical system has definite potential as a viable replacement option for the conventional system should it be combined with an appropriate alternator and equipped with an efficient control system.
- Full Text:
- Date Issued: 2007
- Authors: Marais, Charel
- Date: 2007
- Subjects: Automobiles -- Air conditioning , Electric vehicles -- Power supply , Automobiles -- Fuel systems , Electric automobiles
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9623 , http://hdl.handle.net/10948/774 , Automobiles -- Air conditioning , Electric vehicles -- Power supply , Automobiles -- Fuel systems , Electric automobiles
- Description: The disturbing current situation regarding the world climate has initiated a major wave of urgent developments towards decreasing the overall impact of human activities on the living environment. A major role player in this development is the automobile industry that is inherently connected to pollution of various types, be it air, water or noise pollution. There have been drastic changes not only in the technologies employed in producing vehicles and components, but also in the construction and technologies built into modern automobiles to lessen the overall environmental impact of the industry. Noxious emissions have been decreased, overall efficiencies increased and vehicles are becoming more economical with each new generation. Stricter laws dictate that the level of acceptable vehicle emissions is to be decreased ever further and all manufacturers are developing various possibilities to achieve this. With the emergence of hybrid vehicle technology, there was also a sudden development of different electrical systems that were made viable by the higher onboard voltage systems employed in hybrid vehicles. One of these developments was the electrical air conditioning compressor for use in automobile applications. Although it is designed to operate with a higher voltage than the traditional 12V onboard vehicle systems, it is theoretically possible to incorporate it into a 12V system by making use of a DC-DC converter to step up the supply voltage of the electrical compressor sufficiently to allow for its successful operation. The question therefore arises whether it would be feasible and sensible to employ an electrical air conditioning system in conventional combustion engine vehicles from an overall fuel consumption and vehicle emissions point of view. A modelling approach was taken where an overall vehicle driving simulation was created to represent an average modern production vehicle. The simulation was then extended to include the options of incorporating models for both mechanically and electrically driven air conditioning systems. This provides insight into the influences of the air conditioning system on the vehicle’s overall fuel consumption and an opportunity to compare the influences from the two different systems. This study attempted to provide answers to some of the viability questions regarding the incorporation of electrically driven air conditioning systems into vehicles that use standard 12V onboard voltage systems. It was found that the electrical system has definite potential as a viable replacement option for the conventional system should it be combined with an appropriate alternator and equipped with an efficient control system.
- Full Text:
- Date Issued: 2007
Business process security maturity: a paradigm convergence
- Authors: Box, Debra
- Date: 2008
- Subjects: Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9785 , http://hdl.handle.net/10948/722 , Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Description: Information technology developments in software and hardware have enabled radical changes in information systems, culminating in the paradigm Business Process Management. There has been a concomitant rise in the importance of information security and security engineering due to the increased reliance by society on information. Information is seen as a critical success factor which needs protection. Information security is the response to increased hazards created through recent innovations in Web technology and the advent of intra and inter enterprise-wide systems. Security engineering is based on a variety of codes of practice and security metrics which aim at ameliorating these increased security hazards. Its aim is to produce a balanced set of security needs which are integrated into the system activities to establish confidence in the effectiveness of the security counter-measures. It is generally accepted that security should be applied in an integrated approach, for example, in Information Systems development. This has proved to be a noble thought but is the exception to the rule. Security, historically, is generally applied as an after-thought in an Information Technology implementation. This motivated the concept of formulating a model of integrating security inherently within the paradigm of BPM. The overarching requirements of the model are to align the overall organisational security initiatives and ensure continuous improvement through constant evaluation and adaptation of the security processes. It is the intention of this research to show that these requirements are achievable through aligning the process management methodology of BPM, with the security paradigms of Information Security Management (using the ISO 17799 standard) and security engineering (using the Systems Security Engineering Capability Maturity Model – SSE-CMM). The aim of the Business Process Security Maturity model as the output of this research, is to link the SSE-CMM, as the security metric and appraisal method, to the ISO 17799 security standard, which provides the guidance for the information security management framework and security control selection, within the Business Process Management environment. The SSE-CMM, as the security version of the Capability Maturity Model, provides the necessary strategy to control the security engineering processes that support the information systems and it maintains that as processes mature they become more predictable, effective and manageable. The aim of the model is to provide an integrated, mature security strategy within the business process and monitor and correct the security posture of the implemented counter-measures.
- Full Text:
- Date Issued: 2008
- Authors: Box, Debra
- Date: 2008
- Subjects: Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9785 , http://hdl.handle.net/10948/722 , Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Description: Information technology developments in software and hardware have enabled radical changes in information systems, culminating in the paradigm Business Process Management. There has been a concomitant rise in the importance of information security and security engineering due to the increased reliance by society on information. Information is seen as a critical success factor which needs protection. Information security is the response to increased hazards created through recent innovations in Web technology and the advent of intra and inter enterprise-wide systems. Security engineering is based on a variety of codes of practice and security metrics which aim at ameliorating these increased security hazards. Its aim is to produce a balanced set of security needs which are integrated into the system activities to establish confidence in the effectiveness of the security counter-measures. It is generally accepted that security should be applied in an integrated approach, for example, in Information Systems development. This has proved to be a noble thought but is the exception to the rule. Security, historically, is generally applied as an after-thought in an Information Technology implementation. This motivated the concept of formulating a model of integrating security inherently within the paradigm of BPM. The overarching requirements of the model are to align the overall organisational security initiatives and ensure continuous improvement through constant evaluation and adaptation of the security processes. It is the intention of this research to show that these requirements are achievable through aligning the process management methodology of BPM, with the security paradigms of Information Security Management (using the ISO 17799 standard) and security engineering (using the Systems Security Engineering Capability Maturity Model – SSE-CMM). The aim of the Business Process Security Maturity model as the output of this research, is to link the SSE-CMM, as the security metric and appraisal method, to the ISO 17799 security standard, which provides the guidance for the information security management framework and security control selection, within the Business Process Management environment. The SSE-CMM, as the security version of the Capability Maturity Model, provides the necessary strategy to control the security engineering processes that support the information systems and it maintains that as processes mature they become more predictable, effective and manageable. The aim of the model is to provide an integrated, mature security strategy within the business process and monitor and correct the security posture of the implemented counter-measures.
- Full Text:
- Date Issued: 2008
A model for information security control audit for small to mid-sized organisations
- Authors: Deysel, Natasha
- Date: 2009
- Subjects: Data protection , Computer networks -- Information technology
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9760 , http://hdl.handle.net/10948/940 , Data protection , Computer networks -- Information technology
- Description: Organisations are increasingly dependent on their information. Compromise to this information in terms of loss, inaccuracy or competitors gaining unauthorised access could have devastating consequences for the organisation. Therefore, information security governance has become a major concern for all organisations, large and small. Information security governance is based on a set of policies and internal controls by which organisations direct and manage their information security. An effective information security governance programme should be based on a recognised framework, such as the Control Objectives for Information and related Technology (COBIT). COBIT focuses on what control objectives must be achieved in order to effectively manage the information technology environment. It has become very clear that if a company is serious about information security governance, it needs to apply the COBIT framework that deals with information security. The problem in some medium-sized organisations is that they do not realise the importance of information security governance and are either unaware of the risks or choose to ignore these risks as they do not have the expertise or resources available to provide them with assurance that they have the right information security controls in place to protect their organisation against threats.
- Full Text:
- Date Issued: 2009
- Authors: Deysel, Natasha
- Date: 2009
- Subjects: Data protection , Computer networks -- Information technology
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9760 , http://hdl.handle.net/10948/940 , Data protection , Computer networks -- Information technology
- Description: Organisations are increasingly dependent on their information. Compromise to this information in terms of loss, inaccuracy or competitors gaining unauthorised access could have devastating consequences for the organisation. Therefore, information security governance has become a major concern for all organisations, large and small. Information security governance is based on a set of policies and internal controls by which organisations direct and manage their information security. An effective information security governance programme should be based on a recognised framework, such as the Control Objectives for Information and related Technology (COBIT). COBIT focuses on what control objectives must be achieved in order to effectively manage the information technology environment. It has become very clear that if a company is serious about information security governance, it needs to apply the COBIT framework that deals with information security. The problem in some medium-sized organisations is that they do not realise the importance of information security governance and are either unaware of the risks or choose to ignore these risks as they do not have the expertise or resources available to provide them with assurance that they have the right information security controls in place to protect their organisation against threats.
- Full Text:
- Date Issued: 2009
Enabling e-learning 2.0 in information security education: a semantic web approach
- Authors: Goss, Ryan Gavin
- Date: 2009
- Subjects: Data protection , Computers -- Access control , Electronic data processing -- Security measures , Electronic data processing departments -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9771 , http://hdl.handle.net/10948/909 , Data protection , Computers -- Access control , Electronic data processing -- Security measures , Electronic data processing departments -- Security measures
- Description: The motivation for this study argued that current information security ed- ucation systems are inadequate for educating all users of computer systems world wide in acting securely during their operations with information sys- tems. There is, therefore, a pervasive need for information security knowledge in all aspects of modern life. E-Learning 2.0 could possi- bly contribute to solving this problem, however, little or no knowledge currently exists regarding the suitability and practicality of using such systems to infer information security knowledge to learners.
- Full Text:
- Date Issued: 2009
- Authors: Goss, Ryan Gavin
- Date: 2009
- Subjects: Data protection , Computers -- Access control , Electronic data processing -- Security measures , Electronic data processing departments -- Security measures
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9771 , http://hdl.handle.net/10948/909 , Data protection , Computers -- Access control , Electronic data processing -- Security measures , Electronic data processing departments -- Security measures
- Description: The motivation for this study argued that current information security ed- ucation systems are inadequate for educating all users of computer systems world wide in acting securely during their operations with information sys- tems. There is, therefore, a pervasive need for information security knowledge in all aspects of modern life. E-Learning 2.0 could possi- bly contribute to solving this problem, however, little or no knowledge currently exists regarding the suitability and practicality of using such systems to infer information security knowledge to learners.
- Full Text:
- Date Issued: 2009
Laser surface hardening of AISI 1518 alloy steel
- Authors: Zhang, Tao
- Date: 2010
- Subjects: Lasers , Laser beams , Lasers in engineering , Nd-YAG lasers , Steel alloys , Surfaces -- Effect of radiation on
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9613 , http://hdl.handle.net/10948/723 , Lasers , Laser beams , Lasers in engineering , Nd-YAG lasers , Steel alloys , Surfaces -- Effect of radiation on
- Description: The laser surface hardening process will enhance the hardness profile of automotive components and ensure better process control and predictability of quality as compared to the conventional hardening processes. A 2KW Nd-YAG laser system was used to harden the surface of alloy steel with various process parameters (laser power, focal spot diameter and beam velocity). The results (microhardness, microstructure change and residual stress distribution) were measured and analyzed with Vickers microhardness tester, optical/electron microscope and hole-drilling residual stress equipment. Statistical analyses of the experimental data were used for explaining the relationships between process parameters, microhardness and microstructure. General thermal hardening was applied in the research to show the influence of heating temperature and cooling method on microstructure and mechanical properties. Also, the results were compared with laser surface hardening process from microhardness, microstructure and residual stress to show the advantage of laser surface hardening. Through analysis of the results of the laser surface hardening experiments, a suitable laser power density and interaction time for optimum hardening was obtained. The presented laser surface hardening process can also be applied to other alloy steel surface hardening process.
- Full Text:
- Date Issued: 2010
- Authors: Zhang, Tao
- Date: 2010
- Subjects: Lasers , Laser beams , Lasers in engineering , Nd-YAG lasers , Steel alloys , Surfaces -- Effect of radiation on
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9613 , http://hdl.handle.net/10948/723 , Lasers , Laser beams , Lasers in engineering , Nd-YAG lasers , Steel alloys , Surfaces -- Effect of radiation on
- Description: The laser surface hardening process will enhance the hardness profile of automotive components and ensure better process control and predictability of quality as compared to the conventional hardening processes. A 2KW Nd-YAG laser system was used to harden the surface of alloy steel with various process parameters (laser power, focal spot diameter and beam velocity). The results (microhardness, microstructure change and residual stress distribution) were measured and analyzed with Vickers microhardness tester, optical/electron microscope and hole-drilling residual stress equipment. Statistical analyses of the experimental data were used for explaining the relationships between process parameters, microhardness and microstructure. General thermal hardening was applied in the research to show the influence of heating temperature and cooling method on microstructure and mechanical properties. Also, the results were compared with laser surface hardening process from microhardness, microstructure and residual stress to show the advantage of laser surface hardening. Through analysis of the results of the laser surface hardening experiments, a suitable laser power density and interaction time for optimum hardening was obtained. The presented laser surface hardening process can also be applied to other alloy steel surface hardening process.
- Full Text:
- Date Issued: 2010