Reconstructing ionospheric TEC over South Africa using signals from a regional GPS network
- Authors: Opperman, B D L
- Date: 2008
- Subjects: Global Positioning System Global Positioning System -- Data processing Electrons -- South Africa Ionosphere -- South Africa Ionospheric radio wave propagation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5487 , http://hdl.handle.net/10962/d1005273
- Description: Radio signals transmitted by GPS satellites orbiting the Earth are modulated as they propagate through the electrically charged plasmasphere and ionosphere in the near-Earth space environment. Through a linear combination of GPS range and phase measurements observed on two carrier frequencies by terrestrial-based GPS receivers, the ionospheric total electron content (TEC) along oblique GPS signal paths may be quantified. Simultaneous observations of signals transmitted by multiple GPS satellites and observed from a network of South African dual frequency GPS receivers, constitute a spatially dense ionospheric measurement source over the region. A new methodology, based on an adjusted spherical harmonic (ASHA) expansion, was developed to estimate diurnal vertical TEC over the region using GPS observations over the region. The performance of the ASHA methodology to estimate diurnal TEC and satellite and receiver differential clock biases (DCBs) for a single GPS receiver was first tested with simulation data and subsequently applied to observed GPS data. The resulting diurnal TEC profiles estimated from GPS observations compared favourably to measurements from three South African ionosondes and two other GPS-based methodologies for 2006 solstice and equinox dates. The ASHA methodology was applied to calculating diurnal two-dimensional TEC maps from multiple receivers in the South African GPS network. The space physics application of the newly developed methodology was demonstrated by investigating the ionosphere’s behaviour during a severe geomagnetic storm and investigating the long-term ionospheric stability in support of the proposed Square Kilometre Array (SKA) radio astronomy project. The feasibility of employing the newly developed technique in an operational near real-time system for estimating and dissimenating TEC values over Southern Africa using observations from a regional GPS receiver network, was investigated.
- Full Text:
- Authors: Opperman, B D L
- Date: 2008
- Subjects: Global Positioning System Global Positioning System -- Data processing Electrons -- South Africa Ionosphere -- South Africa Ionospheric radio wave propagation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5487 , http://hdl.handle.net/10962/d1005273
- Description: Radio signals transmitted by GPS satellites orbiting the Earth are modulated as they propagate through the electrically charged plasmasphere and ionosphere in the near-Earth space environment. Through a linear combination of GPS range and phase measurements observed on two carrier frequencies by terrestrial-based GPS receivers, the ionospheric total electron content (TEC) along oblique GPS signal paths may be quantified. Simultaneous observations of signals transmitted by multiple GPS satellites and observed from a network of South African dual frequency GPS receivers, constitute a spatially dense ionospheric measurement source over the region. A new methodology, based on an adjusted spherical harmonic (ASHA) expansion, was developed to estimate diurnal vertical TEC over the region using GPS observations over the region. The performance of the ASHA methodology to estimate diurnal TEC and satellite and receiver differential clock biases (DCBs) for a single GPS receiver was first tested with simulation data and subsequently applied to observed GPS data. The resulting diurnal TEC profiles estimated from GPS observations compared favourably to measurements from three South African ionosondes and two other GPS-based methodologies for 2006 solstice and equinox dates. The ASHA methodology was applied to calculating diurnal two-dimensional TEC maps from multiple receivers in the South African GPS network. The space physics application of the newly developed methodology was demonstrated by investigating the ionosphere’s behaviour during a severe geomagnetic storm and investigating the long-term ionospheric stability in support of the proposed Square Kilometre Array (SKA) radio astronomy project. The feasibility of employing the newly developed technique in an operational near real-time system for estimating and dissimenating TEC values over Southern Africa using observations from a regional GPS receiver network, was investigated.
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The intermediary function of NGOs in HIV/AIDS responses : a case study of the Lady Frere district of the Eastern Cape
- Authors: Mayekiso, Andile
- Date: 2008 , 2013-07-11
- Subjects: HIV infections -- South Africa -- Eastern Cape AIDS (Disease) -- South Africa -- Eastern Cape Non-governmental organizations -- South Africa -- Eastern Cape Community organization -- South Africa -- Eastern Cape HIV infections -- Social aspects -- South Africa -- Eastern Cape AIDS (Disease) -- Social aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3354 , http://hdl.handle.net/10962/d1007584
- Description: The HIV/AIDS epidemic has serious effects on society. It has been described as the biggest threat to the development of South Africa, with severe economic, social and human impact. In the Lady Frere District in the Eastern Cape Province, like in many other areas that are greatly affected by the epidemic in this country, young people are considered by the local Department of Health to be a particularly vulnerable group due to various predisposing biological, social, cultural, and economical factors. Despite the efforts that have been made to educate and encourage prevention, especially by the local Masibambane Non-governmental Organisation (MNGO) to inform these communities about the dangers of the epidemic, people's behaviour have been slow to change and the disease continues to spread. This research is conducted against the escalating HIV / AIDS pandemic in the Lady Frere District. The fundamental aim of this project is to examine the intermediary function of the MNGO in HIV/AIDS responses. The study seeks to evaluate the way in which this local NGO operates on the ground in contributing to a community's response to the HIV/AIDS pandemic. In other words, the thesis tries to indicate how this local NGO, in dealing with the HIV/AIDS issue, interfaces with the community and related stakeholders. It examines how young people in the Lady Frere District perceive HIV/AIDS. A literature review demonstrates that the specific aims and objectives of this project represent a fairly new area of research in South Africa. I propose in the thesis that a simple act of joining and being regularly involved in a community organisation such as the MNGO will have significant impact on individuals' health and well-being. The thesis is crying for a need to restore the notion of "ubuntu" (meaning humanity) which is fundamentally based on social capital to assist these communities to rebuild trust which is essential in people living with HIV/AIDS. Based on my assessment it seems that intermediary NGOs, like the traditional NGOs and the private sector, will have little impact in terms of changing the conditions of the poor and the marginalised people. This is because in practice, like the conventional NGOs, intermediary NGOs serve the interests of donors and national governments or those who give them financial support to continue existing.
- Full Text:
- Authors: Mayekiso, Andile
- Date: 2008 , 2013-07-11
- Subjects: HIV infections -- South Africa -- Eastern Cape AIDS (Disease) -- South Africa -- Eastern Cape Non-governmental organizations -- South Africa -- Eastern Cape Community organization -- South Africa -- Eastern Cape HIV infections -- Social aspects -- South Africa -- Eastern Cape AIDS (Disease) -- Social aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3354 , http://hdl.handle.net/10962/d1007584
- Description: The HIV/AIDS epidemic has serious effects on society. It has been described as the biggest threat to the development of South Africa, with severe economic, social and human impact. In the Lady Frere District in the Eastern Cape Province, like in many other areas that are greatly affected by the epidemic in this country, young people are considered by the local Department of Health to be a particularly vulnerable group due to various predisposing biological, social, cultural, and economical factors. Despite the efforts that have been made to educate and encourage prevention, especially by the local Masibambane Non-governmental Organisation (MNGO) to inform these communities about the dangers of the epidemic, people's behaviour have been slow to change and the disease continues to spread. This research is conducted against the escalating HIV / AIDS pandemic in the Lady Frere District. The fundamental aim of this project is to examine the intermediary function of the MNGO in HIV/AIDS responses. The study seeks to evaluate the way in which this local NGO operates on the ground in contributing to a community's response to the HIV/AIDS pandemic. In other words, the thesis tries to indicate how this local NGO, in dealing with the HIV/AIDS issue, interfaces with the community and related stakeholders. It examines how young people in the Lady Frere District perceive HIV/AIDS. A literature review demonstrates that the specific aims and objectives of this project represent a fairly new area of research in South Africa. I propose in the thesis that a simple act of joining and being regularly involved in a community organisation such as the MNGO will have significant impact on individuals' health and well-being. The thesis is crying for a need to restore the notion of "ubuntu" (meaning humanity) which is fundamentally based on social capital to assist these communities to rebuild trust which is essential in people living with HIV/AIDS. Based on my assessment it seems that intermediary NGOs, like the traditional NGOs and the private sector, will have little impact in terms of changing the conditions of the poor and the marginalised people. This is because in practice, like the conventional NGOs, intermediary NGOs serve the interests of donors and national governments or those who give them financial support to continue existing.
- Full Text:
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