A critical analysis of the influence of the "Prevention of the illegal eviction from and unlawful occupation of Land Act 19 of 1998" on investment in residential income-producing property
- Authors: Botha, Brink
- Date: 2004
- Subjects: Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11005 , http://hdl.handle.net/10948/321 , Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Description: This research will focus on the influence of legislation (as indicated in this research) on the investment decision in residential income-producing property. Assumptions, as recorded in the hypothesis of this study, indicate that the legislation had a changing influence on the investment decision in residential income-producing property in comparison to the time period prior to the promulgation of the legislation. The research methodology will be based on a comparative analysis of the current legislation and the proposed Draft Amendment Bill. This analysis will be tested by means of a case study analysis incorporating a phenomenological study based on written data. The problems, sub-problems and hypothesis will be addressed and tested in this research in conjunction with the prescribed research methodology. This research is concluded by means of a synopsis and recommendations.
- Full Text:
- Date Issued: 2004
- Authors: Botha, Brink
- Date: 2004
- Subjects: Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11005 , http://hdl.handle.net/10948/321 , Rental housing -- Law and legislation -- South Africa , Eviction -- Law and legislation -- South Africa , Occupancy (Law) -- South Africa , Real estate investment -- Law and legislation -- South Africa
- Description: This research will focus on the influence of legislation (as indicated in this research) on the investment decision in residential income-producing property. Assumptions, as recorded in the hypothesis of this study, indicate that the legislation had a changing influence on the investment decision in residential income-producing property in comparison to the time period prior to the promulgation of the legislation. The research methodology will be based on a comparative analysis of the current legislation and the proposed Draft Amendment Bill. This analysis will be tested by means of a case study analysis incorporating a phenomenological study based on written data. The problems, sub-problems and hypothesis will be addressed and tested in this research in conjunction with the prescribed research methodology. This research is concluded by means of a synopsis and recommendations.
- Full Text:
- Date Issued: 2004
A critical evaluation of the analytical method used for the separation and estimation of copper and nickel
- Authors: Sismey, J E
- Date: 1948
- Subjects: Copper -- Analysis , Nickel -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4519 , http://hdl.handle.net/10962/d1014335
- Description: [From Introduction]. This thesis deals with the determination of copper and nickel both separately and in each other's presence. The work is divided into two sections, one of which treats the subject from the theoretical side while the other contains an account of the practical work performed by the author. In the theoretical section, an attempt is made to summarise the better-known methods for the determination of copper and nickel, and at the same time, to incorporate such improvements, criticism and variations as have appeared in the literature. The subject is so vast that its summary in so short a space must necessarily be incomplete. Yoe and Server, for example, quote 111 references on the subject of the nickel-dimethylglyoxine with other ions. Only a fraction of the literature was available, and space permitted only a fraction of this to be abstracted in the following pages.
- Full Text:
- Date Issued: 1948
- Authors: Sismey, J E
- Date: 1948
- Subjects: Copper -- Analysis , Nickel -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4519 , http://hdl.handle.net/10962/d1014335
- Description: [From Introduction]. This thesis deals with the determination of copper and nickel both separately and in each other's presence. The work is divided into two sections, one of which treats the subject from the theoretical side while the other contains an account of the practical work performed by the author. In the theoretical section, an attempt is made to summarise the better-known methods for the determination of copper and nickel, and at the same time, to incorporate such improvements, criticism and variations as have appeared in the literature. The subject is so vast that its summary in so short a space must necessarily be incomplete. Yoe and Server, for example, quote 111 references on the subject of the nickel-dimethylglyoxine with other ions. Only a fraction of the literature was available, and space permitted only a fraction of this to be abstracted in the following pages.
- Full Text:
- Date Issued: 1948
A critical study of assessments made during a trial interview situation
- Authors: Pons, A L
- Date: 1951
- Subjects: Interviewing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3226 , http://hdl.handle.net/10962/d1013040
- Description: At the end of 1948 the National Institute for Personnel Research (N.I.P.R.) organised a series of testing procedures for the selection of administrative trainees for a large industrial organisation. The fruitful results obtained by the British War Office and the Civil Service selection Boards in the application of approved techniques for similar purposes supplied the basis on which the battery of tests was constructed. While having regard for this established approach as well as the controlling influence imposed by the stipulations of the contract, the N.I.P.R. was able to devise a battery which provided scope for its specific interest in research. Intro., p. 1.
- Full Text:
- Date Issued: 1951
- Authors: Pons, A L
- Date: 1951
- Subjects: Interviewing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3226 , http://hdl.handle.net/10962/d1013040
- Description: At the end of 1948 the National Institute for Personnel Research (N.I.P.R.) organised a series of testing procedures for the selection of administrative trainees for a large industrial organisation. The fruitful results obtained by the British War Office and the Civil Service selection Boards in the application of approved techniques for similar purposes supplied the basis on which the battery of tests was constructed. While having regard for this established approach as well as the controlling influence imposed by the stipulations of the contract, the N.I.P.R. was able to devise a battery which provided scope for its specific interest in research. Intro., p. 1.
- Full Text:
- Date Issued: 1951
A critical study of methods for the determination of zinc in soils and plant materials
- Authors: Eve, Desmond John
- Date: 1955
- Subjects: Soils -- Zinc content , Soils -- Analysis , Plants -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4468 , http://hdl.handle.net/10962/d1011770 , Soils -- Zinc content , Soils -- Analysis , Plants -- Analysis
- Description: Although it is only fairly recently that the importance of trace elements in plant nutrition has been established, enormous advances have been made in this field of research and numerous publications of considerable scientific and economic importance, dealing with the subject, have appeared. The physiological functions of zinc in promoting plant growth have not all been satisfactorily identified as yet. There are indications, however, that zinc acts as a catalyst or regulator in plant metabolism. It appears too, that the element plays some role in chlorophyll formation. Zinc deficiency is associated with leaf chlorosis and a general collapse of v ital processes. The analysis of leaves and soils has become an essential part of the study of the nutritional diseases of plants and it is imperative that accurate and reliable methods of analysis should be available. Intro. p. 1.
- Full Text:
- Date Issued: 1955
- Authors: Eve, Desmond John
- Date: 1955
- Subjects: Soils -- Zinc content , Soils -- Analysis , Plants -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4468 , http://hdl.handle.net/10962/d1011770 , Soils -- Zinc content , Soils -- Analysis , Plants -- Analysis
- Description: Although it is only fairly recently that the importance of trace elements in plant nutrition has been established, enormous advances have been made in this field of research and numerous publications of considerable scientific and economic importance, dealing with the subject, have appeared. The physiological functions of zinc in promoting plant growth have not all been satisfactorily identified as yet. There are indications, however, that zinc acts as a catalyst or regulator in plant metabolism. It appears too, that the element plays some role in chlorophyll formation. Zinc deficiency is associated with leaf chlorosis and a general collapse of v ital processes. The analysis of leaves and soils has become an essential part of the study of the nutritional diseases of plants and it is imperative that accurate and reliable methods of analysis should be available. Intro. p. 1.
- Full Text:
- Date Issued: 1955
A critical study of the curcumin method for the determination of boron in plant material
- Authors: Davidson, R J
- Date: 1958
- Subjects: Plants -- Nutrition , Boron , Turmeric
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4458 , http://hdl.handle.net/10962/d1011003
- Description: Methods for the determination of boron are reviewed. A thorough investigation of the curcumin method was undertaken. Factors such as spectral absorption, boron volatilisation and the effects of pH, the stability of reagents and colour solutions, the drying of reaction products and the interference from certain elements, were investigated. A study of the efficiency of extracting boron from plant material using an ashing procedure is presented. The modified curcumin method for the determination of boron in plant material is described. The statistical accuracy and precision of the modified method is presented. The modified method was used to determine the boron content in citrus and pineapple leaf samples obtained from various parts of the Eastern Cape.
- Full Text:
- Date Issued: 1958
- Authors: Davidson, R J
- Date: 1958
- Subjects: Plants -- Nutrition , Boron , Turmeric
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4458 , http://hdl.handle.net/10962/d1011003
- Description: Methods for the determination of boron are reviewed. A thorough investigation of the curcumin method was undertaken. Factors such as spectral absorption, boron volatilisation and the effects of pH, the stability of reagents and colour solutions, the drying of reaction products and the interference from certain elements, were investigated. A study of the efficiency of extracting boron from plant material using an ashing procedure is presented. The modified curcumin method for the determination of boron in plant material is described. The statistical accuracy and precision of the modified method is presented. The modified method was used to determine the boron content in citrus and pineapple leaf samples obtained from various parts of the Eastern Cape.
- Full Text:
- Date Issued: 1958
A critical study of the determination of molybdenum in plant material
- Authors: Gore, William Tompson
- Date: 1961
- Subjects: Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4477 , http://hdl.handle.net/10962/d1012071 , Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Description: 1. Polarographic and spectrophotometric methods for the determination of molybdenum were reviewed. 2. The inclusion of salicylaldoxine in several supporting electrolytes was examined with a view to developing a polarographic procedure, suitable for routine analyses, which did not necessitate a preliminary time-consuming separation stage. A stable molybdenum wave was obtained from an electrolyte having a composition similar to the test solution obtained after the wet digestion of plant material. The height of the wave was found to be, over an optimum range, independent of the reagent concentrations. The wave was however distorted by a maximum, which rendered it unsuitable for quantitative analytical application. 3. The spectrophotometric procedure for molybdenum using thiocyanate is virtually specific and was examined critically. Modifications were found to improve the sensitivity of the procedure, and the stability of the chromatic compound. 4. The modified spectrophotometric procedure is recommended for the routine determination of molybdenum in plant material.
- Full Text:
- Date Issued: 1961
- Authors: Gore, William Tompson
- Date: 1961
- Subjects: Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4477 , http://hdl.handle.net/10962/d1012071 , Molybdenum , Plants -- Analysis , Spectrophotometry , Polarography
- Description: 1. Polarographic and spectrophotometric methods for the determination of molybdenum were reviewed. 2. The inclusion of salicylaldoxine in several supporting electrolytes was examined with a view to developing a polarographic procedure, suitable for routine analyses, which did not necessitate a preliminary time-consuming separation stage. A stable molybdenum wave was obtained from an electrolyte having a composition similar to the test solution obtained after the wet digestion of plant material. The height of the wave was found to be, over an optimum range, independent of the reagent concentrations. The wave was however distorted by a maximum, which rendered it unsuitable for quantitative analytical application. 3. The spectrophotometric procedure for molybdenum using thiocyanate is virtually specific and was examined critically. Modifications were found to improve the sensitivity of the procedure, and the stability of the chromatic compound. 4. The modified spectrophotometric procedure is recommended for the routine determination of molybdenum in plant material.
- Full Text:
- Date Issued: 1961
A crowdsensing method for water resource monitoring in smart communities
- Authors: Banda, Clara Mloza
- Date: 2019
- Subjects: Data collection platforms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42449 , vital:36658
- Description: Crowdsensing aims to empower a large group of individuals to collect large amounts of data using their mobile devices, with the goal of sharing the collected data. Existing crowdsensing studies do not consider all the activities and methods of the crowdsensing process and the key success factors related to the process. Nor do they investigate the profile and behaviour of potential participants. The aim of this study was to design a crowdsensing method for water resource monitoring in smart communities. This study opted for an exploratory study using the Engaged Scholarship approach, which allows the study of complex real-world problems based on the different perspectives of key stakeholders. The proposed Crowdsensing Method considers the social, technical and programme design components. The study proposes a programme design for the Crowdsensing Methodwhich is crowdsensing ReferenceFrameworkthat includes Crowdsensing Processwith key success factors and guidelines that should be considered in each phase of the process. The method also uses the Theory of Planned Behaviour (TPB) to investigate citizens’intention to participate in crowdsensing for water resource monitoring and explores their attitudes, norms and perceived behavioural control on these intentions. Understanding the profiles of potential participants can assist with designing crowdsensing systems with appropriate incentive mechanisms to achieve adequate user participation and good service quality. A survey was conducted to validate the theoretical TB model in a real-world context. Regression and correlation analyses demonstrated that the attitudes, norms and perceived behavioural control can be used to predict participants’ intention to participate in crowdsensing for water resource monitoring. The survey results assisted with the development of an Incentive Mechanism as part of the Crowdsensing Method. This mechanism incorporates recruitment and incentive policies, as well as guidelines derived from the literature review and extant system analysis. The policies, called the OverSensepolicies, provide guidance for recruitment and rewarding of participants using the popular Stackelberg technique. The policies were evaluated using simulation experiments with a data set provided by the case study, the Nelson Mandela Bay Municipality. The results of the simulation experiments illustrated that the OverSenserecruitmentpolicycan reduce the computing resources required for the recruitment of participants and that the recruitment policy performs better than random or naïve recruitment policies. The proposed Crowdsensing Method was evaluated using an ecosystem of success factors for mobile-based interventions identified in the literature and the Crowdsensing Method adhered to a majority (90%) of the success factors. This study also contributes information systems design theory by proposing several sets of guidelines for crowdsensing projects and the development of crowdsensing systems. This study fulfils an identified need to study the applicability of crowdsensing for water resource monitoring and explores how a crowdsensing method can create a smart community.
- Full Text:
- Date Issued: 2019
- Authors: Banda, Clara Mloza
- Date: 2019
- Subjects: Data collection platforms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42449 , vital:36658
- Description: Crowdsensing aims to empower a large group of individuals to collect large amounts of data using their mobile devices, with the goal of sharing the collected data. Existing crowdsensing studies do not consider all the activities and methods of the crowdsensing process and the key success factors related to the process. Nor do they investigate the profile and behaviour of potential participants. The aim of this study was to design a crowdsensing method for water resource monitoring in smart communities. This study opted for an exploratory study using the Engaged Scholarship approach, which allows the study of complex real-world problems based on the different perspectives of key stakeholders. The proposed Crowdsensing Method considers the social, technical and programme design components. The study proposes a programme design for the Crowdsensing Methodwhich is crowdsensing ReferenceFrameworkthat includes Crowdsensing Processwith key success factors and guidelines that should be considered in each phase of the process. The method also uses the Theory of Planned Behaviour (TPB) to investigate citizens’intention to participate in crowdsensing for water resource monitoring and explores their attitudes, norms and perceived behavioural control on these intentions. Understanding the profiles of potential participants can assist with designing crowdsensing systems with appropriate incentive mechanisms to achieve adequate user participation and good service quality. A survey was conducted to validate the theoretical TB model in a real-world context. Regression and correlation analyses demonstrated that the attitudes, norms and perceived behavioural control can be used to predict participants’ intention to participate in crowdsensing for water resource monitoring. The survey results assisted with the development of an Incentive Mechanism as part of the Crowdsensing Method. This mechanism incorporates recruitment and incentive policies, as well as guidelines derived from the literature review and extant system analysis. The policies, called the OverSensepolicies, provide guidance for recruitment and rewarding of participants using the popular Stackelberg technique. The policies were evaluated using simulation experiments with a data set provided by the case study, the Nelson Mandela Bay Municipality. The results of the simulation experiments illustrated that the OverSenserecruitmentpolicycan reduce the computing resources required for the recruitment of participants and that the recruitment policy performs better than random or naïve recruitment policies. The proposed Crowdsensing Method was evaluated using an ecosystem of success factors for mobile-based interventions identified in the literature and the Crowdsensing Method adhered to a majority (90%) of the success factors. This study also contributes information systems design theory by proposing several sets of guidelines for crowdsensing projects and the development of crowdsensing systems. This study fulfils an identified need to study the applicability of crowdsensing for water resource monitoring and explores how a crowdsensing method can create a smart community.
- Full Text:
- Date Issued: 2019
A deep learning approach to classifying tyres using sidewall images
- Authors: Gifford, Dean
- Date: 2019
- Subjects: Image processing -- Digital techniques , Image processing Computer science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39720 , vital:35351
- Description: End of Life Tyres (ELT's) pose a potential health and environmental risk when dumped in illegal stockpiles. For recycling to be considered feasible, a profitable business opportunity needs to be created. One method of making the recycling process of tyres more profitable is by understanding the compounds found within each tyre. This study aims at classifying these tyres in order to achieve this knowledge. A literature review was done to investigate neural networks, convolutional neural networks as well as existing deep learning architectures for image classification. A deep learning approach was applied in order to classify the logos of tyres as these approaches have proved their success in both image classification and more specifically logo classification. Although tyre classification has been implemented in the past, a deep learning approach has not been applied and the logo has not been the classifying element in any other studies. The main difference of this study compared to previous research surrounding deep learning and logo classification is the properties of the tyre logo. Logos on tyres are very similar in colour as they are purely formed in rubber and very seldom have any colour to them. Additionally, the embossed logos can contain variation among same branded tyres due to small inconsistencies in the moulds. The implementation of this deep learning solution saw multiple convolutional neural networks implemented. Some of these architectures were also implemented using transferred learning. The metrics obtained as outputs from training and testing the architectures were the accuracy, precision, recall, and F1-score. These metrics were compared in conjunction with the confusion matrix produced from testing. To ensure that variance was accounted for in the experiments, the k-fold cross-validation technique was adopted. The results of this study identified that one convolutional neural network model, MobileNet, was particularly well suited for the context of classifying logos on tyre sidewalls. The MobileNet architecture had the highest performance metrics for both training from scratch (96.7% accuracy) and transferred learning (98.8% accuracy). Three other models performed particularly well when trained from scratch, these were a modification of the LeNet architecture, ResNet50 and InceptionV3. The transferred learning results were also impressive with four out of the 5 models achieving an accuracy above 94%. Interestingly, the ResNet50 architecture failed to train when transferred learning was applied. Contrasting to this, the two models VGG16 and VGG19 failed to train when trained from scratch but performed equally as well as the other models when transferred learning was implemented. This indicates that although transferred learning can improve the performance of models, it is highly dependent on the task as well as the model. Overall the results obtained proved that a deep learning approach could be applied in order to classify tyres accurately.
- Full Text:
- Date Issued: 2019
- Authors: Gifford, Dean
- Date: 2019
- Subjects: Image processing -- Digital techniques , Image processing Computer science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39720 , vital:35351
- Description: End of Life Tyres (ELT's) pose a potential health and environmental risk when dumped in illegal stockpiles. For recycling to be considered feasible, a profitable business opportunity needs to be created. One method of making the recycling process of tyres more profitable is by understanding the compounds found within each tyre. This study aims at classifying these tyres in order to achieve this knowledge. A literature review was done to investigate neural networks, convolutional neural networks as well as existing deep learning architectures for image classification. A deep learning approach was applied in order to classify the logos of tyres as these approaches have proved their success in both image classification and more specifically logo classification. Although tyre classification has been implemented in the past, a deep learning approach has not been applied and the logo has not been the classifying element in any other studies. The main difference of this study compared to previous research surrounding deep learning and logo classification is the properties of the tyre logo. Logos on tyres are very similar in colour as they are purely formed in rubber and very seldom have any colour to them. Additionally, the embossed logos can contain variation among same branded tyres due to small inconsistencies in the moulds. The implementation of this deep learning solution saw multiple convolutional neural networks implemented. Some of these architectures were also implemented using transferred learning. The metrics obtained as outputs from training and testing the architectures were the accuracy, precision, recall, and F1-score. These metrics were compared in conjunction with the confusion matrix produced from testing. To ensure that variance was accounted for in the experiments, the k-fold cross-validation technique was adopted. The results of this study identified that one convolutional neural network model, MobileNet, was particularly well suited for the context of classifying logos on tyre sidewalls. The MobileNet architecture had the highest performance metrics for both training from scratch (96.7% accuracy) and transferred learning (98.8% accuracy). Three other models performed particularly well when trained from scratch, these were a modification of the LeNet architecture, ResNet50 and InceptionV3. The transferred learning results were also impressive with four out of the 5 models achieving an accuracy above 94%. Interestingly, the ResNet50 architecture failed to train when transferred learning was applied. Contrasting to this, the two models VGG16 and VGG19 failed to train when trained from scratch but performed equally as well as the other models when transferred learning was implemented. This indicates that although transferred learning can improve the performance of models, it is highly dependent on the task as well as the model. Overall the results obtained proved that a deep learning approach could be applied in order to classify tyres accurately.
- Full Text:
- Date Issued: 2019
A derivation of the the black-scholes equation using martingales
- Authors: Nyarko , Ebenezer Narh
- Date: 2018
- Subjects: Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14572 , vital:40016
- Description: This work focuses on the application of stochastic differential equations, with martingales, in finance. The emphasis is on the derivation of the Black-Scholes model for the valuation of options. A theoretical framework in stochastic analysis, together with Itô calculus (Kiyoshi Itô), is explored. The Girsanov Theorem is applied in order to transform a modelled stochastic equation based, on predetermined stock and bond prices, into equivalent martingale measures. A replication strategy is then adopted to solve the two equations analytically, by finding the natural logarithm of the expectation of the solution to the stochastic models. We finally compute the resulting solution based on a standard, normal distribution to get the desired outcome of the Black-Scholes model.
- Full Text:
- Date Issued: 2018
- Authors: Nyarko , Ebenezer Narh
- Date: 2018
- Subjects: Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14572 , vital:40016
- Description: This work focuses on the application of stochastic differential equations, with martingales, in finance. The emphasis is on the derivation of the Black-Scholes model for the valuation of options. A theoretical framework in stochastic analysis, together with Itô calculus (Kiyoshi Itô), is explored. The Girsanov Theorem is applied in order to transform a modelled stochastic equation based, on predetermined stock and bond prices, into equivalent martingale measures. A replication strategy is then adopted to solve the two equations analytically, by finding the natural logarithm of the expectation of the solution to the stochastic models. We finally compute the resulting solution based on a standard, normal distribution to get the desired outcome of the Black-Scholes model.
- Full Text:
- Date Issued: 2018
A description of spatial and temporal aspects of the lifecycle of chokka squid Loligo vulgaris reynaudii on the inshore spawning grounds and Agulhas bank off the South Coast of South Africa
- Authors: Olyott, Leonard James Henry
- Date: 2002
- Subjects: Squids -- South Africa , Loliginidae -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5253 , http://hdl.handle.net/10962/d1005096 , Squids -- South Africa , Loliginidae -- South Africa
- Description: The chokka squid, Loligo vulgaris reynaudii, is a commercially important species supporting a large, high-value export fishery for South Africa. This study reviewed its population dynamics and reproductive biology. Biological information collected on biannual research cruises from September 1986 to April 1999 on the Agulhas Bank as well as information from commercial vessels operating in the inshore environment collected between April 1988 and July 1989 and again between June 1999 and May 2000 were analysed. Size ranges of juveniles, subadults and adults were calculated and used to determine seasonal distribution and abundance patterns. Based on Gonadosomatic Indices (GSI) and percentages of mature squid in each month, two peak reproductive seasons in summer and winter were identified although mature squid were present all year round. Seasonal peaks in sex ratio were also apparent with males outnumbering females by up to 4:1 in the peak-breeding season. The size at which squid matured, demonstrated both spatial and temporal patterns. Squid caught in spring matured at a smaller size than squid caught in autumn and at successively smaller sizes from west to east across the Agulhas Bank. Size at maturity was highly variable especially in males where “sneaker males” were evident in both seasons. Length-to-weight linear regression revealed significant differences between maturity stages and between sexes. Females demonstrated steeper length-to-weight regression slopes than males in the peak-breeding seasons. Aspects of squid biology pertinent to fishery management were highlighted as well as potential areas where research should be directed in order to develop future stock assessment models.
- Full Text:
- Date Issued: 2002
- Authors: Olyott, Leonard James Henry
- Date: 2002
- Subjects: Squids -- South Africa , Loliginidae -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5253 , http://hdl.handle.net/10962/d1005096 , Squids -- South Africa , Loliginidae -- South Africa
- Description: The chokka squid, Loligo vulgaris reynaudii, is a commercially important species supporting a large, high-value export fishery for South Africa. This study reviewed its population dynamics and reproductive biology. Biological information collected on biannual research cruises from September 1986 to April 1999 on the Agulhas Bank as well as information from commercial vessels operating in the inshore environment collected between April 1988 and July 1989 and again between June 1999 and May 2000 were analysed. Size ranges of juveniles, subadults and adults were calculated and used to determine seasonal distribution and abundance patterns. Based on Gonadosomatic Indices (GSI) and percentages of mature squid in each month, two peak reproductive seasons in summer and winter were identified although mature squid were present all year round. Seasonal peaks in sex ratio were also apparent with males outnumbering females by up to 4:1 in the peak-breeding season. The size at which squid matured, demonstrated both spatial and temporal patterns. Squid caught in spring matured at a smaller size than squid caught in autumn and at successively smaller sizes from west to east across the Agulhas Bank. Size at maturity was highly variable especially in males where “sneaker males” were evident in both seasons. Length-to-weight linear regression revealed significant differences between maturity stages and between sexes. Females demonstrated steeper length-to-weight regression slopes than males in the peak-breeding seasons. Aspects of squid biology pertinent to fishery management were highlighted as well as potential areas where research should be directed in order to develop future stock assessment models.
- Full Text:
- Date Issued: 2002
A detailed investigation of interoperability for web services
- Authors: Wright, Madeleine
- Date: 2006
- Subjects: Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4592 , http://hdl.handle.net/10962/d1004832 , Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Description: The thesis presents a qualitative survey of web services' interoperability, offering a snapshot of development and trends at the end of 2005. It starts by examining the beginnings of web services in earlier distributed computing and middleware technologies, determining the distance from these approaches evident in current web-services architectures. It establishes a working definition of web services, examining the protocols that now seek to define it and the extent to which they contribute to its most crucial feature, interoperability. The thesis then considers the REST approach to web services as being in a class of its own, concluding that this approach to interoperable distributed computing is not only the simplest but also the most interoperable. It looks briefly at interoperability issues raised by technologies in the wider arena of Service Oriented Architecture. The chapter on protocols is complemented by a chapter that validates the qualitative findings by examining web services in practice. These have been implemented by a variety of toolkits and on different platforms. Included in the study is a preliminary examination of JAX-WS, the replacement for JAX-RPC, which is still under development. Although the main language of implementation is Java, the study includes services in C# and PHP and one implementation of a client using a Firefox extension. The study concludes that different forms of web service may co-exist with earlier middleware technologies. While remaining aware that there are still pitfalls that might yet derail the movement towards greater interoperability, the conclusion sounds an optimistic note that recent cooperation between different vendors may yet result in a solution that achieves interoperability through core web-service standards.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Madeleine
- Date: 2006
- Subjects: Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4592 , http://hdl.handle.net/10962/d1004832 , Firefox , Web services , World Wide Web , Computer architecture , C# (Computer program language) , PHP (Computer program language) , Java (Computer program language)
- Description: The thesis presents a qualitative survey of web services' interoperability, offering a snapshot of development and trends at the end of 2005. It starts by examining the beginnings of web services in earlier distributed computing and middleware technologies, determining the distance from these approaches evident in current web-services architectures. It establishes a working definition of web services, examining the protocols that now seek to define it and the extent to which they contribute to its most crucial feature, interoperability. The thesis then considers the REST approach to web services as being in a class of its own, concluding that this approach to interoperable distributed computing is not only the simplest but also the most interoperable. It looks briefly at interoperability issues raised by technologies in the wider arena of Service Oriented Architecture. The chapter on protocols is complemented by a chapter that validates the qualitative findings by examining web services in practice. These have been implemented by a variety of toolkits and on different platforms. Included in the study is a preliminary examination of JAX-WS, the replacement for JAX-RPC, which is still under development. Although the main language of implementation is Java, the study includes services in C# and PHP and one implementation of a client using a Firefox extension. The study concludes that different forms of web service may co-exist with earlier middleware technologies. While remaining aware that there are still pitfalls that might yet derail the movement towards greater interoperability, the conclusion sounds an optimistic note that recent cooperation between different vendors may yet result in a solution that achieves interoperability through core web-service standards.
- Full Text:
- Date Issued: 2006
A distributed approach to surround sound production
- Authors: Smith, Adrian Wilfrid
- Date: 1999
- Subjects: Surround-sound systems , Computer sound processing , Music -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4602 , http://hdl.handle.net/10962/d1004855 , Surround-sound systems , Computer sound processing , Music -- Data processing
- Description: The requirement for multi-channel surround sound in audio production applications is growing rapidly. Audio processing in these applications can be costly, particularly in multi-channel systems. A distributed approach is proposed for the development of a realtime spatialization system for surround sound music production, using Ambisonic surround sound methods. The latency in the system is analyzed, with a focus on the audio processing and network delays, in order to ascertain the feasibility of an enhanced, distributed real-time spatialization system.
- Full Text:
- Date Issued: 1999
- Authors: Smith, Adrian Wilfrid
- Date: 1999
- Subjects: Surround-sound systems , Computer sound processing , Music -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4602 , http://hdl.handle.net/10962/d1004855 , Surround-sound systems , Computer sound processing , Music -- Data processing
- Description: The requirement for multi-channel surround sound in audio production applications is growing rapidly. Audio processing in these applications can be costly, particularly in multi-channel systems. A distributed approach is proposed for the development of a realtime spatialization system for surround sound music production, using Ambisonic surround sound methods. The latency in the system is analyzed, with a focus on the audio processing and network delays, in order to ascertain the feasibility of an enhanced, distributed real-time spatialization system.
- Full Text:
- Date Issued: 1999
A distributed Linda server on a network of heterogeneous processors
- Authors: Smith, Graham Leslie
- Date: 1993
- Subjects: LINDA (Computer system) , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4610 , http://hdl.handle.net/10962/d1004890 , LINDA (Computer system) , Parallel programming (Computer science)
- Description: Linda is an approach to parallelism which relies on a virtual associative shared memory called tuple space. Tuple space is accessed through a small set of primitive operations and is conceptually easy to understand and manipulate. The physical implementation of a Linda tuple space may of course be completely different from the conceptual model. Rhodes has implemented versions of Linda on a ring of RS-232 joined PC's and on a cluster of T800 transputers with a single copy of tuple space on one transputer. Current research targets the implementation of a distributed Linda server on a network of heterogeneous processors. This work describes the design and implementation of a distributed Linda server. Emphasis is placed on aspects of the design which enhance portability and efficiency.
- Full Text:
- Date Issued: 1993
- Authors: Smith, Graham Leslie
- Date: 1993
- Subjects: LINDA (Computer system) , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4610 , http://hdl.handle.net/10962/d1004890 , LINDA (Computer system) , Parallel programming (Computer science)
- Description: Linda is an approach to parallelism which relies on a virtual associative shared memory called tuple space. Tuple space is accessed through a small set of primitive operations and is conceptually easy to understand and manipulate. The physical implementation of a Linda tuple space may of course be completely different from the conceptual model. Rhodes has implemented versions of Linda on a ring of RS-232 joined PC's and on a cluster of T800 transputers with a single copy of tuple space on one transputer. Current research targets the implementation of a distributed Linda server on a network of heterogeneous processors. This work describes the design and implementation of a distributed Linda server. Emphasis is placed on aspects of the design which enhance portability and efficiency.
- Full Text:
- Date Issued: 1993
A facilities management transformation strategy for the public sector
- Authors: Tonono, Erol
- Date: 2008
- Subjects: Facility management -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9666 , http://hdl.handle.net/10948/767 , Facility management -- South Africa
- Description: Facilities Management (FM) has become one of the fastest growing disciplines in the built environment. Factors such as information technology, expectations of employees, the cost of mistakes in building, the cost of building space and global competition have influenced the growth of the discipline. These factors have forced facilities management to move from the basement to the boardroom; from a hidden function entrusted to the sleepy, slow and steady to one performed by increasingly bright-eyed and dynamic facilities managers. The objectives of this research focus on the need for a transformation strategy for FM in the public sector. However, before any transformation is considered, it is essential to understand the perceptions and attitudes of people dealing with FM in this sector. The National Department of Public Works (NDPW) became the focus of the study because it has the largest property portfolio in the southern hemisphere. It should be the leader in FM. The collected primary data (being quantitative) and secondary information provided the necessary basis to understand the application of FM in the NDPW. The study revealed shortcomings which are contributing to the problems outlined: namely, that no senior manager has been appointed to manage the portfolio and assist top management in decision-making; that neither a policy nor a FM framework are in place to guide the FM portfolio; that there is a lack of knowledge about the discipline, particularly by management and that there is no computer-aided FM in the entire department, let alone a FM helpdesk. FM is the coordination of workplace, people, physical infrastructure, processes and technology in order for an organization to meet its objectives. It is a wide field encompassing models that tend to differ considerably from one organization to another as it has to respond to the particular needs of each organization. It recognizes that a workplace’s configuration can have either a positive or negative impact on productivity, depending on the competency of the FM structures in place.
- Full Text:
- Date Issued: 2008
- Authors: Tonono, Erol
- Date: 2008
- Subjects: Facility management -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9666 , http://hdl.handle.net/10948/767 , Facility management -- South Africa
- Description: Facilities Management (FM) has become one of the fastest growing disciplines in the built environment. Factors such as information technology, expectations of employees, the cost of mistakes in building, the cost of building space and global competition have influenced the growth of the discipline. These factors have forced facilities management to move from the basement to the boardroom; from a hidden function entrusted to the sleepy, slow and steady to one performed by increasingly bright-eyed and dynamic facilities managers. The objectives of this research focus on the need for a transformation strategy for FM in the public sector. However, before any transformation is considered, it is essential to understand the perceptions and attitudes of people dealing with FM in this sector. The National Department of Public Works (NDPW) became the focus of the study because it has the largest property portfolio in the southern hemisphere. It should be the leader in FM. The collected primary data (being quantitative) and secondary information provided the necessary basis to understand the application of FM in the NDPW. The study revealed shortcomings which are contributing to the problems outlined: namely, that no senior manager has been appointed to manage the portfolio and assist top management in decision-making; that neither a policy nor a FM framework are in place to guide the FM portfolio; that there is a lack of knowledge about the discipline, particularly by management and that there is no computer-aided FM in the entire department, let alone a FM helpdesk. FM is the coordination of workplace, people, physical infrastructure, processes and technology in order for an organization to meet its objectives. It is a wide field encompassing models that tend to differ considerably from one organization to another as it has to respond to the particular needs of each organization. It recognizes that a workplace’s configuration can have either a positive or negative impact on productivity, depending on the competency of the FM structures in place.
- Full Text:
- Date Issued: 2008
A feasibility study into the possibility of ionospheric propagation of low VHF (30-35 MHZ) signals between South Africa and Central Africa
- Authors: Coetzee, Petrus Johannes
- Date: 2009
- Subjects: Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5465 , http://hdl.handle.net/10962/d1005250 , Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Description: The role of the South African National Defence Force (SANDF) has changed considerably in the last decade. The emphasis has moved from protecting the country's borders to peacekeeping duties in Central Africa and even further North. Communications between the peacekeeping missions and the military bases back in South Africa is vital to ensure the success of these missions. Currently use is made of satellite as well as High Frequency (HF) communications. There are drawbacks associated with these technologies (high cost and low data rates/interference respectively). Successful long distance ionospheric propagation in the low Very High Frequency (VHF) range will complement the existing infrastructure and enhance the success rate of these missions. This thesis presents a feasibility study to determine under what ionospheric conditions such low VHF communications will be possible. The International Reference Ionosphere (IRI) was used to generate ionospheric data for the reflection point(s) of the signal. The peak height of the ionospheric F2 layer (hmF2) was used to calculate the required antenna elevation angle. Once the elevation angle is known it is possible to calculate the required F2 layer critical frequency (foF2). The required foF2 value was calculated by assuming a Maximum Useable Frequency (MUF) of 20% higher than the planned operational frequency. It was determined that single hop propagation is possible during the daytime if the smoothed sunspot number (SSN) exceeds 15. The most challenging requirement for successful single hop propagation is the need of an antenna height of 23 m. For rapid deployment and semi-mobile operations within a jungle environment it may prove to be a formidable obstacle.
- Full Text:
- Date Issued: 2009
- Authors: Coetzee, Petrus Johannes
- Date: 2009
- Subjects: Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5465 , http://hdl.handle.net/10962/d1005250 , Communications, Military -- South Africa , Communications, Military -- Africa, Central , Digital communications -- South Africa , Digital communications -- Africa, Central , Signals and signaling -- South Africa , Signals and signaling -- Africa, Central , Artificial satellites in telecommunication -- South Africa , Artificial satellites in telecommunication -- Africa, Central , Shortwave radio
- Description: The role of the South African National Defence Force (SANDF) has changed considerably in the last decade. The emphasis has moved from protecting the country's borders to peacekeeping duties in Central Africa and even further North. Communications between the peacekeeping missions and the military bases back in South Africa is vital to ensure the success of these missions. Currently use is made of satellite as well as High Frequency (HF) communications. There are drawbacks associated with these technologies (high cost and low data rates/interference respectively). Successful long distance ionospheric propagation in the low Very High Frequency (VHF) range will complement the existing infrastructure and enhance the success rate of these missions. This thesis presents a feasibility study to determine under what ionospheric conditions such low VHF communications will be possible. The International Reference Ionosphere (IRI) was used to generate ionospheric data for the reflection point(s) of the signal. The peak height of the ionospheric F2 layer (hmF2) was used to calculate the required antenna elevation angle. Once the elevation angle is known it is possible to calculate the required F2 layer critical frequency (foF2). The required foF2 value was calculated by assuming a Maximum Useable Frequency (MUF) of 20% higher than the planned operational frequency. It was determined that single hop propagation is possible during the daytime if the smoothed sunspot number (SSN) exceeds 15. The most challenging requirement for successful single hop propagation is the need of an antenna height of 23 m. For rapid deployment and semi-mobile operations within a jungle environment it may prove to be a formidable obstacle.
- Full Text:
- Date Issued: 2009
A feasibility study into total electron content prediction using neural networks
- Authors: Habarulema, John Bosco
- Date: 2008
- Subjects: Electrons , Neural networks (Computer science) , Global Positioning System , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5466 , http://hdl.handle.net/10962/d1005251 , Electrons , Neural networks (Computer science) , Global Positioning System , Ionosphere , Ionospheric electron density
- Description: Global Positioning System (GPS) networks provide an opportunity to study the dynamics and continuous changes in the ionosphere by supplementing ionospheric measurements which are usually obtained by various techniques such as ionosondes, incoherent scatter radars and satellites. Total electron content (TEC) is one of the physical quantities that can be derived from GPS data, and provides an indication of ionospheric variability. This thesis presents a feasibility study for the development of a Neural Network (NN) based model for the prediction of South African GPS derived TEC. The South African GPS receiver network is operated and maintained by the Chief Directorate Surveys and Mapping (CDSM) in Cape Town, South Africa. Three South African locations were identified and used in the development of an input space and NN architecture for the model. The input space includes the day number (seasonal variation), hour (diurnal variation), sunspot number (measure of the solar activity), and magnetic index(measure of the magnetic activity). An attempt to study the effects of solar wind on TEC variability was carried out using the Advanced Composition Explorer (ACE) data and it is recommended that more study be done using low altitude satellite data. An analysis was done by comparing predicted NN TEC with TEC values from the IRI2001 version of the International Reference Ionosphere (IRI), validating GPS TEC with ionosonde TEC (ITEC) and assessing the performance of the NN model during equinoxes and solstices. Results show that NNs predict GPS TEC more accurately than the IRI at South African GPS locations, but that more good quality GPS data is required before a truly representative empirical GPS TEC model can be released.
- Full Text:
- Date Issued: 2008
- Authors: Habarulema, John Bosco
- Date: 2008
- Subjects: Electrons , Neural networks (Computer science) , Global Positioning System , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5466 , http://hdl.handle.net/10962/d1005251 , Electrons , Neural networks (Computer science) , Global Positioning System , Ionosphere , Ionospheric electron density
- Description: Global Positioning System (GPS) networks provide an opportunity to study the dynamics and continuous changes in the ionosphere by supplementing ionospheric measurements which are usually obtained by various techniques such as ionosondes, incoherent scatter radars and satellites. Total electron content (TEC) is one of the physical quantities that can be derived from GPS data, and provides an indication of ionospheric variability. This thesis presents a feasibility study for the development of a Neural Network (NN) based model for the prediction of South African GPS derived TEC. The South African GPS receiver network is operated and maintained by the Chief Directorate Surveys and Mapping (CDSM) in Cape Town, South Africa. Three South African locations were identified and used in the development of an input space and NN architecture for the model. The input space includes the day number (seasonal variation), hour (diurnal variation), sunspot number (measure of the solar activity), and magnetic index(measure of the magnetic activity). An attempt to study the effects of solar wind on TEC variability was carried out using the Advanced Composition Explorer (ACE) data and it is recommended that more study be done using low altitude satellite data. An analysis was done by comparing predicted NN TEC with TEC values from the IRI2001 version of the International Reference Ionosphere (IRI), validating GPS TEC with ionosonde TEC (ITEC) and assessing the performance of the NN model during equinoxes and solstices. Results show that NNs predict GPS TEC more accurately than the IRI at South African GPS locations, but that more good quality GPS data is required before a truly representative empirical GPS TEC model can be released.
- Full Text:
- Date Issued: 2008
A field investigation into the impact of task demands on worker responses in the South African forestry silviculture sector
- Authors: Parker, Rhiannon Jennifer
- Date: 2014
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Blue collar workers -- South Africa -- KwaZulu-Natal , Manual work -- South Africa -- KwaZulu-Natal , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5157 , http://hdl.handle.net/10962/d1015645
- Description: Background: In South Africa, limited research has focused on the task demands and workers responses associated with forestry silviculture work, particularly pitting and planting. The methods currently in use are manual, but despite our lack of understanding of the existing demands, advances in forestry engineering have resulted in an introduction of semi-mechanised versions of these tasks. This project aimed to compare the task demands of silviculture tasks using the current manual techniques and the more modern, semi-mechanised techniques. Methods: A holistic investigation focused on the worker characteristics of a sample of black male pitters and black female planters from the Kwa-Zulu Natal forestry industry, as well as biomechanical (spinal kinematics and L5/S1 forces), physiological (heart rate, oxygen consumption and energy expenditure) and psychophysical (ratings of perceived exertion and body discomfort) responses associated with manual and semi-mechanised pitting and planting. Results: The pitting task saw significant improvements in the spinal kinematic measures as a result of the increased mechanisation, with eight of the 16 recorded variables decreasing to a lower level of risk classification. Physiologically, the manual task was associated with a mean heart rate of 157 bt.min⁻¹ and absolute energy expenditure of 11.27 kcal.min⁻¹, which were not found to be significantly different to the values of 143 bt.min⁻¹ and 9.8 kcal.min⁻¹ recorded during the semi-mechanised technique. Psychophysical responses indicated that the workers perceived manual pitting to be more physically demanding than the semi-mechanised method. The manual and semi-mechanised planting tasks were, in general, found to be acceptable from a spinal kinematics perspective, with the majority of variables classified as low risk. However, the maximum sagittal angle was reduced by more than 20 degrees as a result of the new equipment. The physiological and psychophysical demands associated with manual planting were found to be within acceptable limits. Conclusion: In terms of pitting, it can tentatively be concluded that the semi-mechanised technique is better than the manual one, based on the biomechanical and psychophysical findings, however physiological demands require further investigation. When considering the planting techniques, the semi-mechanised method showed a slight improvement from the biomechanical perspective, but further physiological and psychophysical investigations are needed.
- Full Text:
- Date Issued: 2014
- Authors: Parker, Rhiannon Jennifer
- Date: 2014
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Blue collar workers -- South Africa -- KwaZulu-Natal , Manual work -- South Africa -- KwaZulu-Natal , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5157 , http://hdl.handle.net/10962/d1015645
- Description: Background: In South Africa, limited research has focused on the task demands and workers responses associated with forestry silviculture work, particularly pitting and planting. The methods currently in use are manual, but despite our lack of understanding of the existing demands, advances in forestry engineering have resulted in an introduction of semi-mechanised versions of these tasks. This project aimed to compare the task demands of silviculture tasks using the current manual techniques and the more modern, semi-mechanised techniques. Methods: A holistic investigation focused on the worker characteristics of a sample of black male pitters and black female planters from the Kwa-Zulu Natal forestry industry, as well as biomechanical (spinal kinematics and L5/S1 forces), physiological (heart rate, oxygen consumption and energy expenditure) and psychophysical (ratings of perceived exertion and body discomfort) responses associated with manual and semi-mechanised pitting and planting. Results: The pitting task saw significant improvements in the spinal kinematic measures as a result of the increased mechanisation, with eight of the 16 recorded variables decreasing to a lower level of risk classification. Physiologically, the manual task was associated with a mean heart rate of 157 bt.min⁻¹ and absolute energy expenditure of 11.27 kcal.min⁻¹, which were not found to be significantly different to the values of 143 bt.min⁻¹ and 9.8 kcal.min⁻¹ recorded during the semi-mechanised technique. Psychophysical responses indicated that the workers perceived manual pitting to be more physically demanding than the semi-mechanised method. The manual and semi-mechanised planting tasks were, in general, found to be acceptable from a spinal kinematics perspective, with the majority of variables classified as low risk. However, the maximum sagittal angle was reduced by more than 20 degrees as a result of the new equipment. The physiological and psychophysical demands associated with manual planting were found to be within acceptable limits. Conclusion: In terms of pitting, it can tentatively be concluded that the semi-mechanised technique is better than the manual one, based on the biomechanical and psychophysical findings, however physiological demands require further investigation. When considering the planting techniques, the semi-mechanised method showed a slight improvement from the biomechanical perspective, but further physiological and psychophysical investigations are needed.
- Full Text:
- Date Issued: 2014
A flight of fancy in the Chorister Robin-Chat (Cossypha dichroa) : an isotopic standpoint
- Wolmarans, Milena Helena Louise
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
- Full Text:
- Date Issued: 2015
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
- Full Text:
- Date Issued: 2015
A floristic study of a portion of the Pondoland Centre of Endeminism, Port St Johns, South Africa
- Authors: Cloete, Elizabeth Carinus
- Date: 2005
- Subjects: Endemic plants -- South Africa -- Port St Johns , Phytogeography -- South Africa -- Port St Johns , Plants -- South Africa -- Port St Johns , Alien plants -- South Africa -- Port St Johns
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4188 , http://hdl.handle.net/10962/d1003757 , Endemic plants -- South Africa -- Port St Johns , Phytogeography -- South Africa -- Port St Johns , Plants -- South Africa -- Port St Johns , Alien plants -- South Africa -- Port St Johns
- Description: Analysis of the flora of the Pondoland Centre of Endemism (PCE) recorded 2253 species in the combined checklist of four sites (Port St. Johns, Mkambati, Umtamvuna and Oribi Gorge). Of these 1 % species are endemic to Pondoland, representing 8.7% of the Species, 15% of the genera and 26% of the families of the combined flora. Forty-four percent ofthe combined flora was only recorded from one locality (between 17% and 26% of each flora) and only 12% of the flora was present in all four localities. Of the endemics only sixteen (8%) occurred in all four sites thus each site had its own complement of unique endemics and 21 % endemics were not recorded from any of the four sites. At species level the floras of Mkambati and Umtamvuna were the most similar, followed by that of Umtamvuna and Oribi Gorge. Port St Johns had the least in common with any of the othersites, but more in common with non-neighbours Umtamvuna and Oribi Gorge than with its nearest neighbour Mkambati. Mkambati and Umtamvuna had the largest proportion of PCE endemics and Port St Johns had the lowest. The four sites are quite similar at family level, sharing thirteen families in the top ten family list between them, but much less similar at generic level.
- Full Text:
- Date Issued: 2005
- Authors: Cloete, Elizabeth Carinus
- Date: 2005
- Subjects: Endemic plants -- South Africa -- Port St Johns , Phytogeography -- South Africa -- Port St Johns , Plants -- South Africa -- Port St Johns , Alien plants -- South Africa -- Port St Johns
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4188 , http://hdl.handle.net/10962/d1003757 , Endemic plants -- South Africa -- Port St Johns , Phytogeography -- South Africa -- Port St Johns , Plants -- South Africa -- Port St Johns , Alien plants -- South Africa -- Port St Johns
- Description: Analysis of the flora of the Pondoland Centre of Endemism (PCE) recorded 2253 species in the combined checklist of four sites (Port St. Johns, Mkambati, Umtamvuna and Oribi Gorge). Of these 1 % species are endemic to Pondoland, representing 8.7% of the Species, 15% of the genera and 26% of the families of the combined flora. Forty-four percent ofthe combined flora was only recorded from one locality (between 17% and 26% of each flora) and only 12% of the flora was present in all four localities. Of the endemics only sixteen (8%) occurred in all four sites thus each site had its own complement of unique endemics and 21 % endemics were not recorded from any of the four sites. At species level the floras of Mkambati and Umtamvuna were the most similar, followed by that of Umtamvuna and Oribi Gorge. Port St Johns had the least in common with any of the othersites, but more in common with non-neighbours Umtamvuna and Oribi Gorge than with its nearest neighbour Mkambati. Mkambati and Umtamvuna had the largest proportion of PCE endemics and Port St Johns had the lowest. The four sites are quite similar at family level, sharing thirteen families in the top ten family list between them, but much less similar at generic level.
- Full Text:
- Date Issued: 2005
A fluvial geomorphological study of river rehabilitation in the Kouga region, Eastern Cape
- Authors: Pietersen, Adrian
- Date: 2009
- Subjects: Fluvial geomorphology -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Kouga Riparian Rehabilitation Project , Stream conservation -- South Africa -- Eastern Cape , Wattles (Plants) -- South Africa -- Eastern Cape , Riparian restoration -- South Africa -- Eastern Cape , Acacia mearnsii -- South Africa -- Eastern Cape , Kouga Region (South Africa) , Kouga River (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4887 , http://hdl.handle.net/10962/d1015228
- Description: The Kouga Riparian Rehabilitation Project (KRRP) is seen as a pilot rehabilitation project in the Kouga region that is heavily invaded with Acacia mearnsii along the riparian zones of many mountain streams. Clearing of these black wattles and re-planting of indigenous vegetation are imperative to rehabilitation efforts. In this context, two invaded catchments were identified - the Baviaans and the Heuningnes. The aim of this research is to characterise the effects that the woody alien invasive Acacia mearnsii has had on the river channel morphology of the Baviaans and Heuningnes Rivers. A desktop and initial field analysis of the relevant study area catchments was completed. This was followed by a comparison of the channel morphology of the various study channel reaches using fixed channel transects. Ecological resource quality objectives (RQOs) for river rehabilitation from a fluvial geomorphological viewpoint were then established. A long-term monitoring protocol to assess whether or not these RQOs will be achieved was recommended. Follow-up channel transects were measured post wattle clearance in the Baviaans and short-term (<2yrs) changes in channel form were described. Differences in terms of the effect of Acacia mearnsii on channel form were then interpreted by direct comparison and through statistical analysis. Results indicate a number of significant differences between those channels impacted by black wattle infestation and those channels seen as unimpacted and natural. Short-term changes (<2yrs) that occurred within the study period post Baviaans wattle clearance were shown to be minimal for channel form as well as for bed material. The lack of any clear relationship or explanation between channel form and other channel controls suggests vegetation as the primary control. Vegetation, specifically the invasive alien vegetation, is the key controlling variable acting on channel form in the two study catchments.
- Full Text:
- Date Issued: 2009
- Authors: Pietersen, Adrian
- Date: 2009
- Subjects: Fluvial geomorphology -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Kouga Riparian Rehabilitation Project , Stream conservation -- South Africa -- Eastern Cape , Wattles (Plants) -- South Africa -- Eastern Cape , Riparian restoration -- South Africa -- Eastern Cape , Acacia mearnsii -- South Africa -- Eastern Cape , Kouga Region (South Africa) , Kouga River (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4887 , http://hdl.handle.net/10962/d1015228
- Description: The Kouga Riparian Rehabilitation Project (KRRP) is seen as a pilot rehabilitation project in the Kouga region that is heavily invaded with Acacia mearnsii along the riparian zones of many mountain streams. Clearing of these black wattles and re-planting of indigenous vegetation are imperative to rehabilitation efforts. In this context, two invaded catchments were identified - the Baviaans and the Heuningnes. The aim of this research is to characterise the effects that the woody alien invasive Acacia mearnsii has had on the river channel morphology of the Baviaans and Heuningnes Rivers. A desktop and initial field analysis of the relevant study area catchments was completed. This was followed by a comparison of the channel morphology of the various study channel reaches using fixed channel transects. Ecological resource quality objectives (RQOs) for river rehabilitation from a fluvial geomorphological viewpoint were then established. A long-term monitoring protocol to assess whether or not these RQOs will be achieved was recommended. Follow-up channel transects were measured post wattle clearance in the Baviaans and short-term (<2yrs) changes in channel form were described. Differences in terms of the effect of Acacia mearnsii on channel form were then interpreted by direct comparison and through statistical analysis. Results indicate a number of significant differences between those channels impacted by black wattle infestation and those channels seen as unimpacted and natural. Short-term changes (<2yrs) that occurred within the study period post Baviaans wattle clearance were shown to be minimal for channel form as well as for bed material. The lack of any clear relationship or explanation between channel form and other channel controls suggests vegetation as the primary control. Vegetation, specifically the invasive alien vegetation, is the key controlling variable acting on channel form in the two study catchments.
- Full Text:
- Date Issued: 2009