The influence of project management maturity on project success – A case of private organization’s infrastructure projects
- Authors: Manunga, Felicia
- Date: 2020
- Subjects: Project Management -- South Africa , Construction projects -- Management -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/49909 , vital:41816
- Description: The construction industry is characterised by the high rate of project failures. Industry professionals consider inconsistent project management practices to be a major cause of these failures. A leading contributor to these inconsistent project management practices is that there is no one project management standard followed in the industry, thereby resulting in different interpretations and applications by project managers. Given the intricate nature of construction projects, correct project management practices and project management maturity are paramount in achieving the overall envisaged project benefits,project success and business profit by organisations. As such, this study arose from the desire to improve the prevailing practices in construction projects, particularly in the Private Healthcare Industry. Against this background, the purpose of this study was to develop a framework that aims to improve the prevailing project management practices in infrastructure projects within the Private Healthcare Industry. This was done through evaluating the appropriate frameworks and theories in construction project management practices, project management maturity, and project success concepts. This then led to determining the correct construction project management practices required for the successful execution of infrastructure projects. To achieve this goal, a comprehensive review of literature was conducted that covered a review of project management practices, benefits, and theories The review of literature concluded with the main study proposition: Project management maturity has an influence on project success.
- Full Text:
- Date Issued: 2020
- Authors: Manunga, Felicia
- Date: 2020
- Subjects: Project Management -- South Africa , Construction projects -- Management -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/49909 , vital:41816
- Description: The construction industry is characterised by the high rate of project failures. Industry professionals consider inconsistent project management practices to be a major cause of these failures. A leading contributor to these inconsistent project management practices is that there is no one project management standard followed in the industry, thereby resulting in different interpretations and applications by project managers. Given the intricate nature of construction projects, correct project management practices and project management maturity are paramount in achieving the overall envisaged project benefits,project success and business profit by organisations. As such, this study arose from the desire to improve the prevailing practices in construction projects, particularly in the Private Healthcare Industry. Against this background, the purpose of this study was to develop a framework that aims to improve the prevailing project management practices in infrastructure projects within the Private Healthcare Industry. This was done through evaluating the appropriate frameworks and theories in construction project management practices, project management maturity, and project success concepts. This then led to determining the correct construction project management practices required for the successful execution of infrastructure projects. To achieve this goal, a comprehensive review of literature was conducted that covered a review of project management practices, benefits, and theories The review of literature concluded with the main study proposition: Project management maturity has an influence on project success.
- Full Text:
- Date Issued: 2020
Development of InSb/GaSb quantum dots by MOVPE
- Authors: Ahia, Chinedu Christian
- Date: 2018
- Subjects: Semiconductors , Quantum electronics Organometallic compounds
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23382 , vital:30537
- Description: There has been an increasing interest in the modification of semiconductor band structures through the reduction of their dimensions, which simultaneously increases the band gap energy of the material and gives rise to flexibility in device properties. Advances in III-V antimony (Sb) based semiconductor fabrication have triggered the quest for extension of the emission/absorption wavelength range of this family of compounds for optoelectronic devices operating in the mid-infrared region of the electromagnetic spectrum. An interesting material system for mid-infrared (MIR) applications is indium antimonide (InSb) quantum dots (QDs) within a gallium antimonide (GaSb) matrix. However, its band alignment and emission wavelength has been the subject of some interest and controversy over the years. This study focuses on the development of InSb/GaSb QDs by metal organic vapour phase epitaxy (MOVPE). The samples were grown on different substrates using various growth parameters in order to vary the size, density and aspect ratio of the dots. Interfacial growth interruptions while flowing various source precursors through the reactor were investigated in order to influence the chemical termination of the surface, and hence the resulting strain in the structures. The samples were characterized using photoluminescence spectroscopy, scanning probe microscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Likewise, the band alignment, energy levels, and carrier wave functions of the samples in this work were modelled theoretically using the nextnanomat software (version 3.1.0.0). A comparison of growth on two different GaSb substrates [(100) 2° off towards <111>B ± 0.1ᵒ and (111) ± 0.1ᵒ] using similar growth conditions yielded a higher dot density on the (100) substrate compared to the (111) substrate. This was attributed to the presence of terraces/atomic steps induced by the misorientation on the (100) substrate, which invariably gives rise to increased adsorption and an enhanced sticking coefficient of adatoms. Studies on the influence of a buffer layer on the morphology of uncapped dots showed that the shape and size of the dots are sensitive to the thickness of the buffer layer. In some case a corrugated buffer surface resulted, which introduced order in the arrangement of the dots, which formed preferentially inside the troughs. An increase in the V/III ratio from 1.0 to 3.0 was found to reduce the areal density of the QDs, while an analysis of the diameter histograms showed a narrowing of the size distribution with an increase in V/III ratio. The larger size distribution at low V/III was ascribed to the increase in indium species and the increased indium adatom migration length. This leads to increased dot density and nucleation sites, and thus triggers an increase in the conversion of tiny QDs into thermodynamically more suitable larger dots via coalescence. However, as the V/III ratio increased, the number of indium adatoms available for growth on the surface reduced, which automatically led to a decrease in the migration length of indium species which is unfavourable for the production of nucleation sites and to a decrease in dot density. Low growth rates were found to be beneficial for the growth of a high density (~5×1010cm-2) of QDs. Photoluminescence (PL) analysis of the capped samples at low temperature (~10 K), using an excitation power of 2 mW, showed a PL peak at ∼732 meV. Upon an increase in laser power to 120 mW, a blue shift of ∼ 8 meV was noticed. This emission typically persisted up to 60–70 K. An increase in the number of InSb QD-layers, was observed to cause an increase in the luminescence spectral line width and a long-wavelength shift of the PL lines, together with an enhancement in the strength of the PL emission. However, high resolution transmission electron microscopy (HRTEM) of the capped dots revealed the formation of an InGaSb quantum well-like structure, ∼10 nm thick, which was responsible for the PL signal mentioned above. The absence of QDs in the capped sample was attributed to inter-diffusion of Ga and In during the deposition of the cap layer, giving rise to a quantum well (QW) instead of the intended QDs. The presence of threading dislocations and stacking faults were also observed in the TEM micrographs of the samples containing multilayers, which can account for the fast quenching of the PL emission with increasing temperature from these samples. Theoretical simulations of the band alignment, wave functions and energy levels were in good agreement with the data collected from the PL spectra of the samples.
- Full Text:
- Date Issued: 2018
- Authors: Ahia, Chinedu Christian
- Date: 2018
- Subjects: Semiconductors , Quantum electronics Organometallic compounds
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23382 , vital:30537
- Description: There has been an increasing interest in the modification of semiconductor band structures through the reduction of their dimensions, which simultaneously increases the band gap energy of the material and gives rise to flexibility in device properties. Advances in III-V antimony (Sb) based semiconductor fabrication have triggered the quest for extension of the emission/absorption wavelength range of this family of compounds for optoelectronic devices operating in the mid-infrared region of the electromagnetic spectrum. An interesting material system for mid-infrared (MIR) applications is indium antimonide (InSb) quantum dots (QDs) within a gallium antimonide (GaSb) matrix. However, its band alignment and emission wavelength has been the subject of some interest and controversy over the years. This study focuses on the development of InSb/GaSb QDs by metal organic vapour phase epitaxy (MOVPE). The samples were grown on different substrates using various growth parameters in order to vary the size, density and aspect ratio of the dots. Interfacial growth interruptions while flowing various source precursors through the reactor were investigated in order to influence the chemical termination of the surface, and hence the resulting strain in the structures. The samples were characterized using photoluminescence spectroscopy, scanning probe microscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Likewise, the band alignment, energy levels, and carrier wave functions of the samples in this work were modelled theoretically using the nextnanomat software (version 3.1.0.0). A comparison of growth on two different GaSb substrates [(100) 2° off towards <111>B ± 0.1ᵒ and (111) ± 0.1ᵒ] using similar growth conditions yielded a higher dot density on the (100) substrate compared to the (111) substrate. This was attributed to the presence of terraces/atomic steps induced by the misorientation on the (100) substrate, which invariably gives rise to increased adsorption and an enhanced sticking coefficient of adatoms. Studies on the influence of a buffer layer on the morphology of uncapped dots showed that the shape and size of the dots are sensitive to the thickness of the buffer layer. In some case a corrugated buffer surface resulted, which introduced order in the arrangement of the dots, which formed preferentially inside the troughs. An increase in the V/III ratio from 1.0 to 3.0 was found to reduce the areal density of the QDs, while an analysis of the diameter histograms showed a narrowing of the size distribution with an increase in V/III ratio. The larger size distribution at low V/III was ascribed to the increase in indium species and the increased indium adatom migration length. This leads to increased dot density and nucleation sites, and thus triggers an increase in the conversion of tiny QDs into thermodynamically more suitable larger dots via coalescence. However, as the V/III ratio increased, the number of indium adatoms available for growth on the surface reduced, which automatically led to a decrease in the migration length of indium species which is unfavourable for the production of nucleation sites and to a decrease in dot density. Low growth rates were found to be beneficial for the growth of a high density (~5×1010cm-2) of QDs. Photoluminescence (PL) analysis of the capped samples at low temperature (~10 K), using an excitation power of 2 mW, showed a PL peak at ∼732 meV. Upon an increase in laser power to 120 mW, a blue shift of ∼ 8 meV was noticed. This emission typically persisted up to 60–70 K. An increase in the number of InSb QD-layers, was observed to cause an increase in the luminescence spectral line width and a long-wavelength shift of the PL lines, together with an enhancement in the strength of the PL emission. However, high resolution transmission electron microscopy (HRTEM) of the capped dots revealed the formation of an InGaSb quantum well-like structure, ∼10 nm thick, which was responsible for the PL signal mentioned above. The absence of QDs in the capped sample was attributed to inter-diffusion of Ga and In during the deposition of the cap layer, giving rise to a quantum well (QW) instead of the intended QDs. The presence of threading dislocations and stacking faults were also observed in the TEM micrographs of the samples containing multilayers, which can account for the fast quenching of the PL emission with increasing temperature from these samples. Theoretical simulations of the band alignment, wave functions and energy levels were in good agreement with the data collected from the PL spectra of the samples.
- Full Text:
- Date Issued: 2018
Statistical comparison of international size-based equity index using a mixture distribution
- Authors: Ngundze, Unathi
- Date: 2011
- Subjects: Mixture distributions (Probability theory) , Finance -- Statistics , Investment analysis , Portfolio management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10576 , http://hdl.handle.net/10948/d1012367 , Mixture distributions (Probability theory) , Finance -- Statistics , Investment analysis , Portfolio management
- Description: Investors and financial analysts spend an inordinate amount of time, resources and effort in an attempt to perfect the science of maximising the level of financial returns. To this end, the field of distribution modelling and analysis of firm size effect is important as an investment analysis and appraisal tool. Numerous studies have been conducted to determine which distribution best fits stock returns (Mandelbrot, 1963; Fama, 1965 and Akgiray and Booth, 1988). Analysis and review of earlier research has revealed that researchers claim that the returns follow a normal distribution. However, the findings have not been without their own limitations in terms of the empirical results in that many also say that the research done does not account for the fat tails and skewness of the data. Some research studies dealing with the anomaly of firm size effect have led to the conclusion that smaller firms tend to command higher returns relative to their larger counterparts with a similar risk profile (Banz, 1981). Recently, Janse van Rensburg et al. (2009a) conducted a study in which both non- normality of stock returns and firm size effect were addressed simultaneously. They used a scale mixture of two normal distributions to compare the stock returns of large capitalisation and small capitalisation shares portfolios. The study concluded that in periods of high volatility, the small capitalisation portfolio is far more risky than the large capitalisation portfolio. In periods of low volatility they are equally risky. Janse van Rensburg et al. (2009a) identified a number of limitations to the study. These included data problems, survivorship bias, exclusion of dividends, and the use of standard statistical tests in the presence of non-normality. They concluded that it was difficult to generalise findings because of the use of only two (limited) portfolios. In the extension of the research, Janse van Rensburg (2009b) concluded that a scale mixture of two normal distributions provided a more superior fit than any other mixture. The scope of this research is an extension of the work by Janse van Rensburg et al. (2009a) and Janse van Rensburg (2009b), with a view to addressing several of the limitations and findings of the earlier studies. The Janse van rensburg (2009b) study was based on data from the Johannesburg Stock Exchange (JSE); this study seeks to compare their research by looking at the New York Stock Exchange (NYSE) to determine if similar results occur in developed markets. For analysis purposes, this study used the statistical software package R (R Development Core Team 2008) and its package mixtools (Young, Benaglia, Chauveau, Elmore, Hettmansperg, Hunter, Thomas, Xuan 2008). Some computation was also done using Microsoft Excel. This dissertation is arranged as follows: Chapter 2 is a literature review of some of the baseline studies and research that supports the conclusion that earlier research finding had serious limitations. Chapter 3 describes the data used in the study and gives a breakdown of portfolio formation and the methodology used in the study. Chapter 4 provides the statistical background of the methods used in this study. Chapter 5 presents the statistical analysis and distribution fitting of the data. Finally, Chapter 6 gives conclusions drawn from the results obtained in the analysis of data as well as recommendations for future work.
- Full Text:
- Date Issued: 2011
- Authors: Ngundze, Unathi
- Date: 2011
- Subjects: Mixture distributions (Probability theory) , Finance -- Statistics , Investment analysis , Portfolio management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10576 , http://hdl.handle.net/10948/d1012367 , Mixture distributions (Probability theory) , Finance -- Statistics , Investment analysis , Portfolio management
- Description: Investors and financial analysts spend an inordinate amount of time, resources and effort in an attempt to perfect the science of maximising the level of financial returns. To this end, the field of distribution modelling and analysis of firm size effect is important as an investment analysis and appraisal tool. Numerous studies have been conducted to determine which distribution best fits stock returns (Mandelbrot, 1963; Fama, 1965 and Akgiray and Booth, 1988). Analysis and review of earlier research has revealed that researchers claim that the returns follow a normal distribution. However, the findings have not been without their own limitations in terms of the empirical results in that many also say that the research done does not account for the fat tails and skewness of the data. Some research studies dealing with the anomaly of firm size effect have led to the conclusion that smaller firms tend to command higher returns relative to their larger counterparts with a similar risk profile (Banz, 1981). Recently, Janse van Rensburg et al. (2009a) conducted a study in which both non- normality of stock returns and firm size effect were addressed simultaneously. They used a scale mixture of two normal distributions to compare the stock returns of large capitalisation and small capitalisation shares portfolios. The study concluded that in periods of high volatility, the small capitalisation portfolio is far more risky than the large capitalisation portfolio. In periods of low volatility they are equally risky. Janse van Rensburg et al. (2009a) identified a number of limitations to the study. These included data problems, survivorship bias, exclusion of dividends, and the use of standard statistical tests in the presence of non-normality. They concluded that it was difficult to generalise findings because of the use of only two (limited) portfolios. In the extension of the research, Janse van Rensburg (2009b) concluded that a scale mixture of two normal distributions provided a more superior fit than any other mixture. The scope of this research is an extension of the work by Janse van Rensburg et al. (2009a) and Janse van Rensburg (2009b), with a view to addressing several of the limitations and findings of the earlier studies. The Janse van rensburg (2009b) study was based on data from the Johannesburg Stock Exchange (JSE); this study seeks to compare their research by looking at the New York Stock Exchange (NYSE) to determine if similar results occur in developed markets. For analysis purposes, this study used the statistical software package R (R Development Core Team 2008) and its package mixtools (Young, Benaglia, Chauveau, Elmore, Hettmansperg, Hunter, Thomas, Xuan 2008). Some computation was also done using Microsoft Excel. This dissertation is arranged as follows: Chapter 2 is a literature review of some of the baseline studies and research that supports the conclusion that earlier research finding had serious limitations. Chapter 3 describes the data used in the study and gives a breakdown of portfolio formation and the methodology used in the study. Chapter 4 provides the statistical background of the methods used in this study. Chapter 5 presents the statistical analysis and distribution fitting of the data. Finally, Chapter 6 gives conclusions drawn from the results obtained in the analysis of data as well as recommendations for future work.
- Full Text:
- Date Issued: 2011
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