H. Sithole - Academia.edu (original) (raw)

Papers by H. Sithole

IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium, 2008

The first few years of tropical forest restoration can be expensive, especially when applied to e... more The first few years of tropical forest restoration can be expensive, especially when applied to expansive areas. In light of this, passive restoration has been recommended as a considerably cheaper or even free alternative. There are, however, both direct and indirect costs associated with passive restoration. First, the longer recovery time that is typically required in passive restoration can be perceived as project failure, especially when compared with nearby active restoration efforts. In the worst-case scenario, this can lead to the premature termination of a project by a landowner who would like to see more rapid or visible results. Second, passive restoration may be viewed as land abandonment, and in developing nations where land tenure is not always strictly enforced this may invite unanticipated uses, such as ranchers who may unintentionally or intentionally allow livestock to take advantage of the "unused" forage grass, thus setting back recovery efforts. Lastly, passive restoration does have direct financial costs, including material costs for establishing fences and repairing them, and labor costs for site vigilance. These upfront investments may need to be made repeatedly in passive restoration efforts, and for a longer time period than for an active restoration project. Both the direct and indirect costs should be considered prior to choosing passive restoration as a strategy in a particular restoration project.

2014 IST-Africa Conference Proceedings, 2014

Advances in Information Technology have brought about cloud computing, an evolutionary computing ... more Advances in Information Technology have brought about cloud computing, an evolutionary computing practice that facilitates the provisioning of computing services as a utility. Cloud computing has brought about change in the economics and sustainability of Information and Communication Technology (ICT) enabled service provision. In South Africa, major aspects of public cloud computing or cloud in general have not yet been developed and realised and in some cases not even researched, hence the struggle to reach the full promises of public cloud computing locally. Whilst a lot of development and progress worldwide has already been made in the public cloud space, there still remains a wide range of concerns that still need to be addressed in order for it to reach its full potential, more specifically in the South African context. A study identifying fundamental services needed by the community and possibilities for and potential impacts of delivering public services in line with the concept of a cloud of public services is conducted. This paper designs a cloud business model that suits South Africa's perspective. The idea is to model a government public cloud which does not interfere with the secured business functions of the government but find a suitable mechanism to extend government services to the citizens. In adopting this vision, the government must ensure that the cloud service still provides an acceptable level of security risk mitigation and allows government organizations to demonstrate their procedures of meeting legal and statutory obligations as far as information is concerned.

The Journal of Physical Chemistry B, 2000

Atomistic simulation techniques are used to investigate the surface structure, stability and reac... more Atomistic simulation techniques are used to investigate the surface structure, stability and reactivity of pyrite. We introduce a potential model for FeS 2 which reproduces experimental structural parameters, elastic constants and hydration energies of pyrite. We modeled the {100}, {110}, and {111} surfaces of pyrite and calculated the {100} surface to be the most stable and to show little surface relaxation, in agreement with experiment. The surfaces were hydrated by associative adsorption of water molecules which stabilized all three surfaces, especially the unstable {111} surface. The calculated adsorption energy of-47 kJ mol-1 for water on the {100} surface agrees well with an adsorption energy of-42 kJ mol-1 , determined for the stoichiometric (100) surface by temperature-programmed desorption. 1 Adsorption of water molecules at surface sites of lower coordination (four-or three-coordinated) showed increased reactivity of these sites. We calculated an increase in adsorption energy of 50-60 kJ mol-1 per loss of bond. We next created stepped {100} planes in order to model a more realistic {100} surface with one-dimensional defects. Four different steps were investigated in two orthogonal directions. Because of the asymmetry of the sulfur dimers, the geometry of the dimers on the edge showed the dimers either leaning forward (F-steps) or backward (B-steps) with respect to the {100} terrace. We used water molecules as a probe of the reactivity of the different surface sites. Corresponding adsorption sites (terrace, edge or below the step) on the F-and B-steps were found to have different reactivities toward water due to the different adsorption modes of the probe molecule. On the B-steps the increased reactivity of the low-coordinated edge iron atom toward water (approximately-70 kJ mol-1) was outweighed by the network of interactions of the water molecule to atoms on terrace and step wall in the position below the step (-91 kJ mol-1). On the F-steps the four-coordinated edge site was calculated to be the most reactive adsorption site.

Molecular Simulation, 1999

Full relaxation of volume and internal parameters of iron pyrite and marcasite FeS2, has been stu... more Full relaxation of volume and internal parameters of iron pyrite and marcasite FeS2, has been studied using a plane-wave pseudopotential method within the Local Density Approximation to Density Functional Theory (LDA-DFT). We find that the internal parameter u of pyrite decreases with hydrostatic compression. The P-V equation of state falls slightly closer to the experimental curve than a previous unrelaxed

Physics and Chemistry of Minerals, 2003

Worldwide governments are actively looking into cloud computing as a means of increasing efficien... more Worldwide governments are actively looking into cloud computing as a means of increasing efficiency of service delivery and reducing infrastructure costs. As a result of introducing cloud computing, interoperability issues arise and yet it is vital for e-government services to be efficiently achieved; this is also a challenge for the South African government. Systems providing e-services in different organizational units are usually incompatible; hence integration of different units is required. Interoperability therefore becomes one of the main issues for successful e-government development. In response, this project aims at developing a South African government-public cloud model that can be used to address the interoperability issues and further enable the government to benefit from other cloud computing advantages. However, modelling a multidimensional social problem as complex as the public cloud for a national government requires time, knowledge and experience from a wide range of specialization disciplines. This is therefore a long-term project consisting of three main phases. Phase 1 investigates international countries that are already using the public cloud for their government services and illustrates the design from a South African perspective. Phase 2 presents the design and the implementation plan of the SA public cloud. Phase 3 presents the monitoring and evaluation plan to assess the quality and impact of this work, against our action plan. This paper discusses Phase 1 of the project, which is the investigation and design of the public cloud. Cloud computing has been identified as a technology development tool that can be used to address this issue. It is therefore envisaged that a government public cloud will be developed by building a cloud business model to suit the case of South Africa. Key differentiating points between public and private cloud will be realized. The success of the South African public cloud relies on the cooperation of different stakeholders from government, private entities, and academics to citizens. The result of this phase will be used as an input into the second phase .

Advances in Information Technology have brought about cloud computing, an evolutionary computing ... more Advances in Information Technology have brought about cloud computing, an evolutionary computing practice that facilitates the provisioning of computing services as a utility. Cloud computing has brought about change in the economics and sustainability of Information and Communication Technology (ICT) enabled service provision. In South Africa, major aspects of public cloud computing or cloud in general have not yet been developed and realised and in some cases not even researched, hence the struggle to reach the full promises of public cloud computing locally.

IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium, 2008

The first few years of tropical forest restoration can be expensive, especially when applied to e... more The first few years of tropical forest restoration can be expensive, especially when applied to expansive areas. In light of this, passive restoration has been recommended as a considerably cheaper or even free alternative. There are, however, both direct and indirect costs associated with passive restoration. First, the longer recovery time that is typically required in passive restoration can be perceived as project failure, especially when compared with nearby active restoration efforts. In the worst-case scenario, this can lead to the premature termination of a project by a landowner who would like to see more rapid or visible results. Second, passive restoration may be viewed as land abandonment, and in developing nations where land tenure is not always strictly enforced this may invite unanticipated uses, such as ranchers who may unintentionally or intentionally allow livestock to take advantage of the "unused" forage grass, thus setting back recovery efforts. Lastly, passive restoration does have direct financial costs, including material costs for establishing fences and repairing them, and labor costs for site vigilance. These upfront investments may need to be made repeatedly in passive restoration efforts, and for a longer time period than for an active restoration project. Both the direct and indirect costs should be considered prior to choosing passive restoration as a strategy in a particular restoration project.

2014 IST-Africa Conference Proceedings, 2014

Advances in Information Technology have brought about cloud computing, an evolutionary computing ... more Advances in Information Technology have brought about cloud computing, an evolutionary computing practice that facilitates the provisioning of computing services as a utility. Cloud computing has brought about change in the economics and sustainability of Information and Communication Technology (ICT) enabled service provision. In South Africa, major aspects of public cloud computing or cloud in general have not yet been developed and realised and in some cases not even researched, hence the struggle to reach the full promises of public cloud computing locally. Whilst a lot of development and progress worldwide has already been made in the public cloud space, there still remains a wide range of concerns that still need to be addressed in order for it to reach its full potential, more specifically in the South African context. A study identifying fundamental services needed by the community and possibilities for and potential impacts of delivering public services in line with the concept of a cloud of public services is conducted. This paper designs a cloud business model that suits South Africa's perspective. The idea is to model a government public cloud which does not interfere with the secured business functions of the government but find a suitable mechanism to extend government services to the citizens. In adopting this vision, the government must ensure that the cloud service still provides an acceptable level of security risk mitigation and allows government organizations to demonstrate their procedures of meeting legal and statutory obligations as far as information is concerned.

The Journal of Physical Chemistry B, 2000

Atomistic simulation techniques are used to investigate the surface structure, stability and reac... more Atomistic simulation techniques are used to investigate the surface structure, stability and reactivity of pyrite. We introduce a potential model for FeS 2 which reproduces experimental structural parameters, elastic constants and hydration energies of pyrite. We modeled the {100}, {110}, and {111} surfaces of pyrite and calculated the {100} surface to be the most stable and to show little surface relaxation, in agreement with experiment. The surfaces were hydrated by associative adsorption of water molecules which stabilized all three surfaces, especially the unstable {111} surface. The calculated adsorption energy of-47 kJ mol-1 for water on the {100} surface agrees well with an adsorption energy of-42 kJ mol-1 , determined for the stoichiometric (100) surface by temperature-programmed desorption. 1 Adsorption of water molecules at surface sites of lower coordination (four-or three-coordinated) showed increased reactivity of these sites. We calculated an increase in adsorption energy of 50-60 kJ mol-1 per loss of bond. We next created stepped {100} planes in order to model a more realistic {100} surface with one-dimensional defects. Four different steps were investigated in two orthogonal directions. Because of the asymmetry of the sulfur dimers, the geometry of the dimers on the edge showed the dimers either leaning forward (F-steps) or backward (B-steps) with respect to the {100} terrace. We used water molecules as a probe of the reactivity of the different surface sites. Corresponding adsorption sites (terrace, edge or below the step) on the F-and B-steps were found to have different reactivities toward water due to the different adsorption modes of the probe molecule. On the B-steps the increased reactivity of the low-coordinated edge iron atom toward water (approximately-70 kJ mol-1) was outweighed by the network of interactions of the water molecule to atoms on terrace and step wall in the position below the step (-91 kJ mol-1). On the F-steps the four-coordinated edge site was calculated to be the most reactive adsorption site.

Molecular Simulation, 1999

Full relaxation of volume and internal parameters of iron pyrite and marcasite FeS2, has been stu... more Full relaxation of volume and internal parameters of iron pyrite and marcasite FeS2, has been studied using a plane-wave pseudopotential method within the Local Density Approximation to Density Functional Theory (LDA-DFT). We find that the internal parameter u of pyrite decreases with hydrostatic compression. The P-V equation of state falls slightly closer to the experimental curve than a previous unrelaxed

Physics and Chemistry of Minerals, 2003

Worldwide governments are actively looking into cloud computing as a means of increasing efficien... more Worldwide governments are actively looking into cloud computing as a means of increasing efficiency of service delivery and reducing infrastructure costs. As a result of introducing cloud computing, interoperability issues arise and yet it is vital for e-government services to be efficiently achieved; this is also a challenge for the South African government. Systems providing e-services in different organizational units are usually incompatible; hence integration of different units is required. Interoperability therefore becomes one of the main issues for successful e-government development. In response, this project aims at developing a South African government-public cloud model that can be used to address the interoperability issues and further enable the government to benefit from other cloud computing advantages. However, modelling a multidimensional social problem as complex as the public cloud for a national government requires time, knowledge and experience from a wide range of specialization disciplines. This is therefore a long-term project consisting of three main phases. Phase 1 investigates international countries that are already using the public cloud for their government services and illustrates the design from a South African perspective. Phase 2 presents the design and the implementation plan of the SA public cloud. Phase 3 presents the monitoring and evaluation plan to assess the quality and impact of this work, against our action plan. This paper discusses Phase 1 of the project, which is the investigation and design of the public cloud. Cloud computing has been identified as a technology development tool that can be used to address this issue. It is therefore envisaged that a government public cloud will be developed by building a cloud business model to suit the case of South Africa. Key differentiating points between public and private cloud will be realized. The success of the South African public cloud relies on the cooperation of different stakeholders from government, private entities, and academics to citizens. The result of this phase will be used as an input into the second phase .

Advances in Information Technology have brought about cloud computing, an evolutionary computing ... more Advances in Information Technology have brought about cloud computing, an evolutionary computing practice that facilitates the provisioning of computing services as a utility. Cloud computing has brought about change in the economics and sustainability of Information and Communication Technology (ICT) enabled service provision. In South Africa, major aspects of public cloud computing or cloud in general have not yet been developed and realised and in some cases not even researched, hence the struggle to reach the full promises of public cloud computing locally.