Mass housing delivery in addressing housing demand in eThekwini Municipality in KwaZulu-Natal
- Authors: Phiri, Mkhehleni Collen
- Date: 2020
- Subjects: Housing development -- South Africa -- eThekwini Municipality Metropolitan
- Language: English
- Type: Thesis , Masters , MSBE
- Identifier: http://hdl.handle.net/10948/49562 , vital:41736
- Description: This research involved studying and understanding the effectiveness and utility of the mass housing delivery approach to reduce housing demand in the eThekwini Municipality. The study employed a qualitative research approach incorporated with the case study method utilising questionnaires consisting of open and closed ended questions administered to ward councillors. Interviews were conducted with stakeholders involved with low-cost housing. Both structured and unstructured interview techniques were employed. It was found that most people migrate to the city to get closer to workplaces; fast tracking rental accommodation will assist in reducing housing demand. Involvement of community leaders like ward councillors in addressing community needs is essential. Availability of suitable land for housing heavily influences service delivery, government to source more land and make it available for housing. The limited available land can be fully utilised by constructing multi-storey buildings to accommodate more households. It was found that there is a lack of stakeholder involvement and participation in the design and planning of low-cost houses. Government to keep a proper register of people issued with government housing units. Monitoring and follow up during construction and after the handover of the houses found to be lacking on government officials. Eradication of corruption in all stakeholders and departments involved in housing delivery processes will show positive results in the housing sector. Transparency in the housing unit’s allocation is required to ensure proper allocation to needy and deserving beneficiaries.
- Full Text:
- Date Issued: 2020
- Authors: Phiri, Mkhehleni Collen
- Date: 2020
- Subjects: Housing development -- South Africa -- eThekwini Municipality Metropolitan
- Language: English
- Type: Thesis , Masters , MSBE
- Identifier: http://hdl.handle.net/10948/49562 , vital:41736
- Description: This research involved studying and understanding the effectiveness and utility of the mass housing delivery approach to reduce housing demand in the eThekwini Municipality. The study employed a qualitative research approach incorporated with the case study method utilising questionnaires consisting of open and closed ended questions administered to ward councillors. Interviews were conducted with stakeholders involved with low-cost housing. Both structured and unstructured interview techniques were employed. It was found that most people migrate to the city to get closer to workplaces; fast tracking rental accommodation will assist in reducing housing demand. Involvement of community leaders like ward councillors in addressing community needs is essential. Availability of suitable land for housing heavily influences service delivery, government to source more land and make it available for housing. The limited available land can be fully utilised by constructing multi-storey buildings to accommodate more households. It was found that there is a lack of stakeholder involvement and participation in the design and planning of low-cost houses. Government to keep a proper register of people issued with government housing units. Monitoring and follow up during construction and after the handover of the houses found to be lacking on government officials. Eradication of corruption in all stakeholders and departments involved in housing delivery processes will show positive results in the housing sector. Transparency in the housing unit’s allocation is required to ensure proper allocation to needy and deserving beneficiaries.
- Full Text:
- Date Issued: 2020
The impact of re-establishment practices on tree survival, growth and uniformity in South African eucalypt plantations
- Authors: Hechter, Ullrich
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Forest nurseries -- South Africa -- KwaZulu Natal Forest management -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40338 , vital:36142
- Description: Commercial forestry plantations in South Africa play an important role in the economy of the country, contributing 1.2% towards the gross domestic product, as well as with job creation in rural communities. Currently plantation forests occupy 1.1% (1.2 million hectares) of the South African land surface, of which 75 000 hectares are re-established each year. Eucalypts are the preferred species in the commercial forestry industry as they have the ability to grow fast. In addition, desirable characteristics from different eucalypt species can be combined to develop hybrids that can be used to further improve productivity. In South Africa, eucalypt plantations are mostly found in the warm temperate and sub-tropical zones situated in the KwaZulu-Natal and Mpumalanga Provinces. Various strategies are used to increase productivity and maximise site occupancy, including genetic tree improvement, site-species matching, optimising stand densities, management for risk (abiotic and biotic), as well as improved silviculture. Intensive silviculture is practiced by forest companies to maximise initial tree survival and reduce the time to canopy closure. This includes practices such as site preparation, slash management, tree protection, pruning and thinning, fertilisation and vegetation management treatments. Of the silvicultural aspects that are important during re-establishment, pitting, plant quality (plant size) and watering techniques/regimes have all been shown to influence short-term stand productivity. Despite research carried out on these individual components, recommendations as to best operating practices are varied and have changed over the years, with the application of these practices also varying across companies. Furthermore, there is limited published information related to the interaction between these practices, as well as any longer-term impacts of these factors on stand productivity. The objective of the present study was to gain an understanding of the impacts of pitting, plant quality (plant size), planting depth and watering on tree survival, growth and uniformity in South African Eucalyptus plantations. The study was carried out using three separate field trial series. In a first experiment, two field trials compared post-establishment performance of eucalypts planted using various pitting methods. The two trials were planted using Eucalyptus grandis and E. grandis x E. nitens on two contrasting sites, one at Greenhill in the KwaZulu-Natal Midlands and one at Vroegeveld in Mpumalanga. Four manual (notch, agricultural hoe, mattock, road pick) and three motor-manual heads (inverted A, Archimedes screw and Mondi-designed pitting head) were used to prepare and determine the effect of pit size/quality on tree survival, growth and uniformity. The notch pit implement created the smallest pit (1 L volume) compared to the other pitting implements (4 – 6 L volumes). For both trials, pitting method did not have a significant impact on the success of re-establishment or longer-term tree performance (6 yrs 7 mos at Greenhill and 3 yrs 7 mos at Vroegeveld). This indicates that for the sites and the species tested, all pitting implements could be considered viable alternatives. Other factors, such as operational costs, efficiency and ergonomics should be considered when selecting appropriate pitting methods together with tree performance. In a second experiment, three field trials were implemented to test three main factors: plant size (small and large); planting depth (standard and deep); and watering (dry and water planting). The eight treatments (2 x 2 x 2 factorial) were replicated four times and laid out in a randomised complete blocks design. The trials were established across a range of site types (Mt Home in Kwazulu-Natal, Vroegeveld in Mpumalanga and Trust in Zululand) in the summer rainfall region of South Africa using various eucalypt genera (E. dunnii, E. grandis x E. nitens and E. grandis x E. urophylla). Tree performance was assessed, with results up to four, six and seven years presented for the different sites. Results show that planting larger plants had the highest overall survival (x̄ = 81%) compared to smaller plants (x̄ = 58%), which also resulted in improved basal area and volume across all sites. Larger plants were able to tolerate a wider range of site conditions, thus providing an advantage for re-establishment. The cost-to-benefit of this however needs to be assessed, particularly in the context of current operational nursery standards. The benefits of deeper planting and applying water at planting are less clear, but appear to be beneficial under water stress conditions, such as on sandy sites when the weather is hot and dry. A third experiment tested the interaction between different methods of pit preparation (manual versus motor-manual), dry versus water planting, and re-watering at periodic intervals. The experiment consisted of one field trial established with E. dunnii in Greytown, KwaZulu-Natal. Twelve treatments (2 x 6 factorial) were replicated four times and laid out in a split-plot design, with the main factor of watering regime forming the whole plots, and pitting method the sub-plots. Differences in pit size, pit quality and tree performance were assessed. Pit dimensions and soil friability for the two pitting treatments were different, but pit volumes were similar (manually prepared pits = 4.7 L; motor-manually prepared pits = 4.4 L). Differences in pit soil moisture content were detected between dry planting (4.1%) and all other treatments (9.9%). Rainfall occurred in week 1 - 4 after planting (55.2 mm). Subsequently re-watering, relative to watering only at planting, was not beneficial. No significant growth differences occurred between the two pitting methods, nor was there any interaction between the main factors (pitting methods x watering regimes). Survival for dry planting (75%) was significantly lower than all the other treatments (92%), with a weakly significant difference in Biomass index (corrected) (BIc) at one year. Different pit qualities, determined by pitting method, will not significantly affect early eucalypt performance. However, the addition of water or hydrogel (as opposed to dry planting) will improve early eucalypt survival and growth. Eucalypt survival, growth and uniformity in South Africa continue to be impacted by an increase in mechanisation, changing climate conditions and the use of unskilled labour. It is therefore necessary to implement silvicultural practices which improve survival, growth and uniformity. Planting seedlings into good quality pits (regardless of pitting method) with water has shown to improve survival. It is also beneficial in terms of survival to plant larger (prime) plants at a deeper depth especially on sites with drought conditions. Despite all the establishment trials which have been implemented under controlled conditions, high mortality is still experienced and could be due to the lack of knowledge on the effects of plant quality and handling on post planting performance (particularly survival). In future, plant quality and handling in combination with various planting densities and the application of plant stress relievers should be considered to improve survival..
- Full Text:
- Date Issued: 2019
- Authors: Hechter, Ullrich
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- KwaZulu-Natal , Forest nurseries -- South Africa -- KwaZulu Natal Forest management -- South Africa -- KwaZulu Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40338 , vital:36142
- Description: Commercial forestry plantations in South Africa play an important role in the economy of the country, contributing 1.2% towards the gross domestic product, as well as with job creation in rural communities. Currently plantation forests occupy 1.1% (1.2 million hectares) of the South African land surface, of which 75 000 hectares are re-established each year. Eucalypts are the preferred species in the commercial forestry industry as they have the ability to grow fast. In addition, desirable characteristics from different eucalypt species can be combined to develop hybrids that can be used to further improve productivity. In South Africa, eucalypt plantations are mostly found in the warm temperate and sub-tropical zones situated in the KwaZulu-Natal and Mpumalanga Provinces. Various strategies are used to increase productivity and maximise site occupancy, including genetic tree improvement, site-species matching, optimising stand densities, management for risk (abiotic and biotic), as well as improved silviculture. Intensive silviculture is practiced by forest companies to maximise initial tree survival and reduce the time to canopy closure. This includes practices such as site preparation, slash management, tree protection, pruning and thinning, fertilisation and vegetation management treatments. Of the silvicultural aspects that are important during re-establishment, pitting, plant quality (plant size) and watering techniques/regimes have all been shown to influence short-term stand productivity. Despite research carried out on these individual components, recommendations as to best operating practices are varied and have changed over the years, with the application of these practices also varying across companies. Furthermore, there is limited published information related to the interaction between these practices, as well as any longer-term impacts of these factors on stand productivity. The objective of the present study was to gain an understanding of the impacts of pitting, plant quality (plant size), planting depth and watering on tree survival, growth and uniformity in South African Eucalyptus plantations. The study was carried out using three separate field trial series. In a first experiment, two field trials compared post-establishment performance of eucalypts planted using various pitting methods. The two trials were planted using Eucalyptus grandis and E. grandis x E. nitens on two contrasting sites, one at Greenhill in the KwaZulu-Natal Midlands and one at Vroegeveld in Mpumalanga. Four manual (notch, agricultural hoe, mattock, road pick) and three motor-manual heads (inverted A, Archimedes screw and Mondi-designed pitting head) were used to prepare and determine the effect of pit size/quality on tree survival, growth and uniformity. The notch pit implement created the smallest pit (1 L volume) compared to the other pitting implements (4 – 6 L volumes). For both trials, pitting method did not have a significant impact on the success of re-establishment or longer-term tree performance (6 yrs 7 mos at Greenhill and 3 yrs 7 mos at Vroegeveld). This indicates that for the sites and the species tested, all pitting implements could be considered viable alternatives. Other factors, such as operational costs, efficiency and ergonomics should be considered when selecting appropriate pitting methods together with tree performance. In a second experiment, three field trials were implemented to test three main factors: plant size (small and large); planting depth (standard and deep); and watering (dry and water planting). The eight treatments (2 x 2 x 2 factorial) were replicated four times and laid out in a randomised complete blocks design. The trials were established across a range of site types (Mt Home in Kwazulu-Natal, Vroegeveld in Mpumalanga and Trust in Zululand) in the summer rainfall region of South Africa using various eucalypt genera (E. dunnii, E. grandis x E. nitens and E. grandis x E. urophylla). Tree performance was assessed, with results up to four, six and seven years presented for the different sites. Results show that planting larger plants had the highest overall survival (x̄ = 81%) compared to smaller plants (x̄ = 58%), which also resulted in improved basal area and volume across all sites. Larger plants were able to tolerate a wider range of site conditions, thus providing an advantage for re-establishment. The cost-to-benefit of this however needs to be assessed, particularly in the context of current operational nursery standards. The benefits of deeper planting and applying water at planting are less clear, but appear to be beneficial under water stress conditions, such as on sandy sites when the weather is hot and dry. A third experiment tested the interaction between different methods of pit preparation (manual versus motor-manual), dry versus water planting, and re-watering at periodic intervals. The experiment consisted of one field trial established with E. dunnii in Greytown, KwaZulu-Natal. Twelve treatments (2 x 6 factorial) were replicated four times and laid out in a split-plot design, with the main factor of watering regime forming the whole plots, and pitting method the sub-plots. Differences in pit size, pit quality and tree performance were assessed. Pit dimensions and soil friability for the two pitting treatments were different, but pit volumes were similar (manually prepared pits = 4.7 L; motor-manually prepared pits = 4.4 L). Differences in pit soil moisture content were detected between dry planting (4.1%) and all other treatments (9.9%). Rainfall occurred in week 1 - 4 after planting (55.2 mm). Subsequently re-watering, relative to watering only at planting, was not beneficial. No significant growth differences occurred between the two pitting methods, nor was there any interaction between the main factors (pitting methods x watering regimes). Survival for dry planting (75%) was significantly lower than all the other treatments (92%), with a weakly significant difference in Biomass index (corrected) (BIc) at one year. Different pit qualities, determined by pitting method, will not significantly affect early eucalypt performance. However, the addition of water or hydrogel (as opposed to dry planting) will improve early eucalypt survival and growth. Eucalypt survival, growth and uniformity in South Africa continue to be impacted by an increase in mechanisation, changing climate conditions and the use of unskilled labour. It is therefore necessary to implement silvicultural practices which improve survival, growth and uniformity. Planting seedlings into good quality pits (regardless of pitting method) with water has shown to improve survival. It is also beneficial in terms of survival to plant larger (prime) plants at a deeper depth especially on sites with drought conditions. Despite all the establishment trials which have been implemented under controlled conditions, high mortality is still experienced and could be due to the lack of knowledge on the effects of plant quality and handling on post planting performance (particularly survival). In future, plant quality and handling in combination with various planting densities and the application of plant stress relievers should be considered to improve survival..
- Full Text:
- Date Issued: 2019
On the characterization of solar cells using advanced imaging techniques
- Authors: Dix-Peek, Ross Michael
- Date: 2018
- Subjects: Photovoltaic cells
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/17944 , vital:28544
- Description: Photovoltaic (PV) cells are devices capable of producing electricity - in particular, from the abundant resource of sunlight. Solar energy (from PV cells) provides a sustainable alternative to fossil fuel energy sources such as coal and oil. PV cells are typically strung in series in PV modules to generate the current and voltage required for commercial use. However, PV cell performance can be limited by defects and degradation. Under operational conditions due to mismatch and shading, individual cells within a PV module can be forced to operate in their reverse bias regime. Depending on the severity of the reverse bias and the defects present in the cell, the longevity of the cell and/or the module can be affected. Reverse bias (assuming bypass diodes are absent) can result in localised heating that can affect the encapsulant polymer’s longevity as well as degrade the cell’s performance over time. However, under more severe reverse bias, the cell could fail, drastically affecting the performance of the module. PV cells can be characterised using various opto-electronic non-destructive techniques, this provides a set of powerful tools which allow the application of multiple such techniques to the same sample. Furthermore, this allows for an in-depth study of the device. Dark Current-Voltage (I-V) measurements, Electroluminescence (EL), Infrared (IR) thermography, Light Beam Induced Current (LBIC) measurements, and the associated techniques are all examples of such tools and are used within this study. An experimental setup was developed to perform dark I-V measurements, EL imaging, IR thermography and LBIC measurements. Part of the development of the experimental setup was the design of an enclosure in which to perform all the measurements. The enclosure minimised internal reflection, and isolated the experiment from electromagnetic radiation. Due to the complex mathematical model applied to the I-V curve, an Evolutionary Algorithm was used to determine optimal parameter values for the equation. More specifically, a Genetic Algorithm was used in the Parameter Optimisation (or Extraction) of the dark I-V parameters based upon the two-diode model for PV cells. The resulting parameters give an indication of the material and device quality. However, to determine the spatial distribution of the defects that effect the I-V response of the device, various imaging techniques were utilised. LBIC is a technique that uses a focussed light beam to raster scan across the surface of a PV cell. The local photo-induced current/voltage can then be measured and compiled into a response map. LBIC was used to determine the local current response across the device. The intensity distribution of EL signal is related to the local junction voltage and the local quantum efficiency. EL intensity imaging with a Si CCD camera was used to determine the spatial distribution of features visible both in the forward bias and in the reverse bias. The experimental setup utilised had a micron scale resolution. A voltage dependent approach was utilised to further characterise features observed. In forward bias, the local junction varies across the device due to parasitic resistances such as series and shunt resistance. At higher forward bias conditions (in the vicinity of and higher than maximum power voltage), series resistance becomes a limiting factor. Therefore, utilising a voltage dependent approach allows for the determination of a series resistance map from voltage dependent EL images. In reverse bias, localised radiative processes can be imaged. These radiative processes are related to defects in the device, such as Al stains, FeSi2 needles and avalanche breakdown. The processes are related to highly localised current flow; this causes localised heating which degrades the device. The voltage dependent Reverse Bias EL (ReBEL) imaging was also used to determine the local breakdown voltage of radiative reverse features. Dark IR thermography is a technique used in the identification of high current sites that leads to localised Joule heating, particularly in reverse bias. In this study, thermography was used to identify breakdown sites and shunts. The results of this study allow for an in-depth analysis of defects found in multi-crystalline Si PV cells using the opto-electronic techniques mentioned above. The multi-pronged approach allowed from a comparison of the various opto-electronic techniques, as well as a more in-depth characterisation of the defects than if only one technique was used.
- Full Text:
- Date Issued: 2018
- Authors: Dix-Peek, Ross Michael
- Date: 2018
- Subjects: Photovoltaic cells
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/17944 , vital:28544
- Description: Photovoltaic (PV) cells are devices capable of producing electricity - in particular, from the abundant resource of sunlight. Solar energy (from PV cells) provides a sustainable alternative to fossil fuel energy sources such as coal and oil. PV cells are typically strung in series in PV modules to generate the current and voltage required for commercial use. However, PV cell performance can be limited by defects and degradation. Under operational conditions due to mismatch and shading, individual cells within a PV module can be forced to operate in their reverse bias regime. Depending on the severity of the reverse bias and the defects present in the cell, the longevity of the cell and/or the module can be affected. Reverse bias (assuming bypass diodes are absent) can result in localised heating that can affect the encapsulant polymer’s longevity as well as degrade the cell’s performance over time. However, under more severe reverse bias, the cell could fail, drastically affecting the performance of the module. PV cells can be characterised using various opto-electronic non-destructive techniques, this provides a set of powerful tools which allow the application of multiple such techniques to the same sample. Furthermore, this allows for an in-depth study of the device. Dark Current-Voltage (I-V) measurements, Electroluminescence (EL), Infrared (IR) thermography, Light Beam Induced Current (LBIC) measurements, and the associated techniques are all examples of such tools and are used within this study. An experimental setup was developed to perform dark I-V measurements, EL imaging, IR thermography and LBIC measurements. Part of the development of the experimental setup was the design of an enclosure in which to perform all the measurements. The enclosure minimised internal reflection, and isolated the experiment from electromagnetic radiation. Due to the complex mathematical model applied to the I-V curve, an Evolutionary Algorithm was used to determine optimal parameter values for the equation. More specifically, a Genetic Algorithm was used in the Parameter Optimisation (or Extraction) of the dark I-V parameters based upon the two-diode model for PV cells. The resulting parameters give an indication of the material and device quality. However, to determine the spatial distribution of the defects that effect the I-V response of the device, various imaging techniques were utilised. LBIC is a technique that uses a focussed light beam to raster scan across the surface of a PV cell. The local photo-induced current/voltage can then be measured and compiled into a response map. LBIC was used to determine the local current response across the device. The intensity distribution of EL signal is related to the local junction voltage and the local quantum efficiency. EL intensity imaging with a Si CCD camera was used to determine the spatial distribution of features visible both in the forward bias and in the reverse bias. The experimental setup utilised had a micron scale resolution. A voltage dependent approach was utilised to further characterise features observed. In forward bias, the local junction varies across the device due to parasitic resistances such as series and shunt resistance. At higher forward bias conditions (in the vicinity of and higher than maximum power voltage), series resistance becomes a limiting factor. Therefore, utilising a voltage dependent approach allows for the determination of a series resistance map from voltage dependent EL images. In reverse bias, localised radiative processes can be imaged. These radiative processes are related to defects in the device, such as Al stains, FeSi2 needles and avalanche breakdown. The processes are related to highly localised current flow; this causes localised heating which degrades the device. The voltage dependent Reverse Bias EL (ReBEL) imaging was also used to determine the local breakdown voltage of radiative reverse features. Dark IR thermography is a technique used in the identification of high current sites that leads to localised Joule heating, particularly in reverse bias. In this study, thermography was used to identify breakdown sites and shunts. The results of this study allow for an in-depth analysis of defects found in multi-crystalline Si PV cells using the opto-electronic techniques mentioned above. The multi-pronged approach allowed from a comparison of the various opto-electronic techniques, as well as a more in-depth characterisation of the defects than if only one technique was used.
- Full Text:
- Date Issued: 2018
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