The Virtual Network Scheduling Problem for Heterogeneous Network Emulation Testbeds

Network testbeds such as Emulab and the Open Network Laboratory use virtualization to enable users to define end user virtual networks within a shared substrate. This involves mapping users\u27 virtual network nodes onto distinct substrate components and mapping virtual network links onto substrate paths. The mappings guarantee that different users\u27 activities can not interfere with one another. The problem of mapping virtual networks onto a shared substrate is a variant of the general graph embedding problem, long known to be NP-hard. In this paper, we focus on a more general version of the problem that supports advance scheduling of virtual network mappings. We experimentally study the performance of heuristic testbed schedulers in the context of the Open Network Laboratory. Our algorithms incorporate Mixed Integer Programs to optimally solve key subproblems, are fast enough to respond to reservation requests in under one second, and rarely reject requests needlessly

Effects of land-cover - land-use on water quality within the kuils - Eerste River Catchment

Philosophiae Doctor - PhDThe most significant human impacts on the hydrological system are due to land-use change. The conversion of land to agricultural, mining, industrial, or residential uses significantly alters the hydrological characteristics of the land surface and modifies pathways and rates of water flow. If this occurs over large or critical areas of a catchment, it can have significant short and long-term impacts, on the quality of water. While there are methods available to quantify the pollutants in surface water, methods of linking non-point source pollution to water quality at catchment scale are lacking. Therefore, the research presented in this thesis investigated modelling techniques to estimate the effect of land-cover type on water quality. The main goal of the study was to contribute towards improving the understanding of how different landcovers in an urbanizing catchment affect surface water quality. The aim of the research presented in this thesis was to explain how the quality of surface runoff varies on different land-cover types and to provide guidelines for minimizing water pollution that may be occurring in the Kuils-Eerste River catchment. The research objectives were; (1) to establish types and spatial distribution of land-cover types within the Kuils-Eerste River catchment, (2) to establish water quality characteristics of surface runoff from specific land-cover types at the experimental plot level, (3) to establish the contribution of each land-cover type to pollutant loads at the catchment scale. Land-cover characteristics and water quality were investigated using GIS and Remote Sensing tools. The application of these tools resulted in the development of a landcover map with 36 land classifications covering the whole catchment. Land-cover in the catchment is predominantly agricultural with vineyards and grassland covering the northern section of the catchment. Vineyards occupy over 35% of the total area followed by fynbos (indigenous vegetation) (12.5 %), open hard rock area (5.8 %), riparian forest (5.2 %), mountain forest (5 %), dense scrub (4.4 %), and improved grassland (3.6 %). The residential area covers about 14 %. Roads cover 3.4 % of the total area. Surface runoff is responsible for the transportation of large quantities of pollutants that affect the quality of water in the Kuils-Eerste River catchment. The different land-cover types and the distribution and concentration levels of the pollutants are not uniform. Experimental work was conducted at plot scale to understand whether landcover types differed in their contributions to the concentration of water quality attributes emerging from them. Four plots each with a length of 10 m to 12 m and 5 m width were set up. Plot I was set up on open grassland, Plot II represented the neyards, Plot III covered the mountain forests, and Plot IV represented the fynbos landcover. Soil samples analyzed from the experimental plots fell in the category of sandy soil (Sa) with the top layer of Plot IV (fynbos) having loamy sand (LmSa). The soil particle sizes range between fine sand (59.1 % and 78.9 %) to coarse sand (between 7 % and 22 %). The content of clay and silt was between 0.2 % and 2.4 %. Medium sand was between 10.7 % and 17.6 %. In terms of vertical distribution of the particle sizes, a general decrease with respect to the size of particles was noted from the top layer (15 cm) to the bottom layer (30 cm) for all categories of the particle sizes. There was variation in particle size with depth and location within the experimental plots. Two primary methods of collecting water samples were used; grab sampling and composite sampling. The quality of water as represented by the samples collected during storm events during the rainfall season of 2006 and 2007 was used to establish water quality characteristics for the different land-cover types. The concentration of total average suspended solids was highest in the following land-cover types, cemeteries (5.06 mg L-1), arterial roads/main roads (3.94 mg L-1), low density residential informal squatter camps (3.21 mg L-1) and medium density residential informal townships (3.21 mg L-1). Chloride concentrations were high on the following land-cover types, recreation grass/ golf course (2.61 mg L-1), open area/barren land (1.59 mg L- 1), and improved grassland/vegetation crop (1.57 mg L-1). The event mean concentration (EMC) values for NO3-N were high on commercial mercantile (6 mg L-1) and water channel (5 mg L-1). The total phosphorus concentration mean values recorded high values on improved grassland/vegetation crop (3.78 mg L-1), medium density residential informal townships (3mgL-1) and low density residential informal squatter camps (3 mg L-1). Surface runoff may also contribute soil particles into rivers during rainfall events, particularly from areas of disturbed soil, for example areas where market gardening is taking place. The study found that different land cover types contributed differently to nonpoint source pollution. GIS model was used to estimate the diffuse pollution of five pollutants (chloride, phosphorus, TSS, nitrogen and NO3-N) in response to land cover variation using water quality data. The GIS model linked land cover information to diffuse nutrient signatures in response to surface runoff using the Curve Number method and EMC data were developed. Two models (RINSPE and N-SPECT) were used to estimate nonpoint source pollution using various GIS databases. The outputs from the GIS-based model were compared with recommended water quality standards. It was found that the RINSPE model gave accurate results in cases where NPS pollution dominate the total pollutant inputs over a given land cover type. However, the N-SPECT model simulations were too uncertain in cases where there were large numbers of land cover types with diverse NPS pollution load. All land-cover types with concentration values above the recommended national water quality standard were considered as areas that needed measures to mitigate the adverse effects of nonpoint pollution. The expansion of urban areas and agricultural land has a direct effect on land cover types within the catchment. The land cover changes have adverse effect which has a potential to contribute to pollution

Rethinking water service delivery system in Zimbabwe: a case study of Kwekwe Municipality

This study examines the perceived scarcity of household water service delivery in the city of Kwekwe under the Midlands province of Zimbabwe. Kwekwe Municipality appears to be characterized by an erratic supply of clean water for household use. The city of Kwekwe has experienced an unreliable domestic water service delivery system since the beginning of this millennium. This study aims to investigate the causes of the problem, its extent, impact and what could be done to mitigate the problem. The study employs interviews, questionnaires, observations and document analyses to establish that population growth, ageing equipment, a lack of foreign currency and local funding, as well as a lack of expertise and of political will have contributed to the poor domestic water supply in the city of Kwekwe. The city of Kwekwe needs to commit itself to improving the current situation by involving the community, constructing more storage facilities, and by putting monitoring and evaluation mechanisms in place. The research design took the form of a case study of Kwekwe Municipality. A mixture of qualitative and quantitative research designs were used in this study. The qualitative/interpretivist approach was more dominant, allowing some overlapping with the quantitative/positivist paradigm whenever this was considered reasonable. The study sample consisted of a conveniently assembled sample of 120 respondents. The target population for the study comprised of 110 residents of Kwekwe urban and 10 Kwekwe City Municipality Water Authorities from the Works Department. This study focuses on the 4 residential areas of Kwekwe Municipality. The data collection instruments include questionnaires and focus group interviews. Electronically recorded, in-depth interviews were held with the water authorities and the consumers to establish their perceptions on the best practice of the water service delivery system in Zimbabwe. The data collection tools contained a preliminary section on the biological data of the respondents. All data was subjected to either qualitative or quantitative analysis techniques in order to strike a balance between the structured survey instruments and the anecdotes of the respondents. Quantitative data was analyzed using a Statistical Package for Social Sciences (SPSS), while qualitative data was subjected to document analysis which entailed classifying the data, extracting themes, identifying patterns, tallying and quantifying responses and making generalizations out of these patterns. This implies that the research methodology focused on the method, tools and techniques used to assist in achieving the objectives of the study and answering the research questions that the research seeks to address. The term research methodology is used, in this study, to refer to the philosophical assumptions, values, and theories which inform and underpin the way in which a particular research method is used. In this study, the case study research design was used as the operational framework for data gathering. The case study research method is essentially grounded in the interpretive research paradigm. To this end, the study sought the perceptions of both the consumers and the water authorities. The major finding of the study is that the ability of Kwekwe Municipality to provide household water service delivery to its consumers is slightly below average. However, there was a slight improvement in the household water service delivery but consumers are still remaining dissatisfied. Another finding, related to this one, was that the electricity deficiency cost the efficacy of Kwekwe Municipality in its provision of household water service delivery. The study proposes that more studies which seek to interrogate the domestic water service delivery system of the Zimbabwean Municipalities should be embarked upon by the state. The study also recommends that service delivery training programmes be implemented in order to enhance the competence of the water authorities. Furthermore, the study suggests that consumers be placed at the center of household water debates when policies, rules and regulations of the water service delivery system are formulated. Finally, the study implores that municipalities need to have their own reserves and generators for emergency cases during electricity power cuts. It is imperative that the water reservoirs constantly hold 4 days‟ worth of water capacity. The municipality of Kwekwe must refurbish the entire water reticulation system. Municipalities must carry out an audit of water meter readings and also confirm that all water meters are functional. Manpower to read the correct meter reading should be increased in number and must have reliable transport.Thesis (PhD) -- Faculty of Management and Commerce, 201

Design of an Extensible Network Testbed with Heterogeneous Components

Virtualized network infrastructures are currently deployed in both research and commercial contexts. The complexity of the virtualization layer varies greatly in different deployments, ranging from cloud computing environments, to carrier Ethernet applications using stacked VLANs, to networking testbeds. In all of these cases, there are many users sharing the resources of one provider, where each user expects their resources to be isolated from all other users. Our work in this area is focused on network testbeds. In particular, we present the design of the latest version of the Open Network Laboratory (ONL) testbed. This redesign generalizes the underlying infrastructure to support resource extensibility and heterogeneity at a fundamental level. New types of resources (e.g., multicore PCs, FPGAs, network processors, etc) can be added to the testbed without modifying any testbed infrastructure software. Resource types can also be extended to support multiple distinct sets of functionality (e.g., an FPGA might act as a router, a switch, or a traffic generator). Moreover, users can dynamically add new resource extensions without any modification to the existing infrastructure

A bullet laden park: potential for battlefield tourism in the Golden Gate Highlands National Park

This paper follows the recent discovery of thousands of ammunition from the AngloBoer war in the Golden Gate Highlands National Park. We explore the potential of the ammunition to attract tourists and as a stimulant for local economic development. Drawing on focus group discussions, key informant interviews and personal observations, the research established that the local community was eager to benefit because it had previously not benefited from the activities taking place in the park. Because of the historical significance of the ammunition which shaped modern day South Africa, the local community perceive the discovery of the ammunition in the park as a tool for generating tourism products in the park which they previously thought was reserved for the elite few. Drawing on such sentiments, it is imperative that the ammunition sites are urgently conserved, preserved, developed and marketed for the benefit of current and future tourism products

What is in a grave? Conflict between the Golden Gate Highlands National Park management and park inhabitants

This paper discusses the importance of graves which have become a source of conflict between the Golden Gate Highlands National Park (GGHNP) management and people residing in the park. The park management is currently in the process of relocating people who were historically living in the park before its proclamation as a national park. There is massive resistance from the park inhabitants, who vehemently argue that they cannot leave the graves of their relatives and ancestors. The GGHNP is one example of a national park in the world where humans have settled together with wildlife in the park. Living together as parks and people is a stimulant for competition on resource use and conflict on land use, land claims and economic benefits generated from the park. Drawing on focus group discussions, key informant interviews and personal observations, the conflict on graves involves an intense debate which is surrounded by conflicting values and perspectives. Because of this, it is not easy to find common ground owing to diametrically opposed cultural beliefs. Although it is quite clear that the park inhabitants and park management attach a different meaning and importance to graves, policy framework should acknowledge the importance of individual gravesites as they constitute vital indigenous cultural heritage

The Detection of Hot Cores and Complex Organic Molecules in the Large Magellanic Cloud

We report the first extragalactic detection of the complex organic molecules (COMs) dimethyl ether (CH3OCH3) and methyl formate (CH3OCHO) with the Atacama Large Millimeter/submillimeter Array (ALMA). These COMs, together with their parent species methanol (CH3OH), were detected toward two 1.3 mm continuum sources in the N 113 star-forming region in the low-metallicity Large Magellanic Cloud (LMC). Rotational temperatures (${T}_{\mathrm{rot}}\sim 130$ K) and total column densities (${N}_{\mathrm{rot}}\sim {10}^{16}$ cm−2) have been calculated for each source based on multiple transitions of CH3OH. We present the ALMA molecular emission maps for COMs and measured abundances for all detected species. The physical and chemical properties of two sources with COMs detection, and the association with H2O and OH maser emission, indicate that they are hot cores. The fractional abundances of COMs scaled by a factor of 2.5 to account for the lower metallicity in the LMC are comparable to those found at the lower end of the range in Galactic hot cores. Our results have important implications for studies of organic chemistry at higher redshift

The efficacy of education decentralisation policy in Zimbabwe: a case of Kadoma district

The study focused on the efficacy of the democratic education decentralization policy. The study focused on the efficacy of the democratic education decentralization policy implementation of the four schools of Kadoma District in Zimbabwe. The thesis reviewed literature and discussed the concept of the democratic education decentralization policy implementation and how this has been practiced in Zimbabwe. The theoretical basis of democratic education decentralization policies were outlined and the argument for and against the policy discussed. Thus the dissertation explored the concept of education decentralization policy with specific reference to the notions of democratization and participation in Zimbabwe. Besides the qualitative and the quantitative research methods employed, the study was complemented by the observation on the ground and document analysis. The thesis unearthed that; the democratic education decentralization policy is characterized by some successes and problems during implementation of the policy as indicated by the paucity of the teaching and learning resources. The research findings revealed that, there is prevalence of poor learning outcomes at ‘O’ level in schools; the SDCs/SDAs are underutilized sources of school development because they are not fully empowered by the education system since they had a minimum role in participating towards the implementation of the policy in order to acquire the teaching and learning resources at the schools in Kadoma District. The above findings long-established the view held by critical theorists of the Participatory Governance Model that there is a complementary relationship between the participation of the SDC/SDA in acquiring the teaching as well as the learning resources and the academic performance of learners. Thus, the study concluded that decentralization policy implementation was the major driving force in strengthening efficiency and accountability of resources and results.mplementation of the four schools of Kadoma District in Zimbabwe. The thesis reviewed literature and discussed the concept of the democratic education decentralization policy implementation and how this has been practiced in Zimbabwe. The theoretical basis of democratic education decentralization policies were outlined and the argument for and against the policy discussed. Thus the dissertation explored the concept of education decentralization policy with specific reference to the notions of democratization and participation in Zimbabwe. Besides the qualitative and the quantitative research methods employed, the study was complemented by the observation on the ground and document analysis. The thesis unearthed that; the democratic education decentralization policy is characterized by some successes and problems during implementation of the policy as indicated by the paucity of the teaching and learning resources. The research findings revealed that, there is prevalence of poor learning outcomes at ‘O’ level in schools; the SDCs/SDAs are underutilized sources of school development because they are not fully empowered by the education system since they had a minimum role in participating towards the implementation of the policy in order to acquire the teaching and learning resources at the schools in Kadoma District. The above findings long-established the view held by critical theorists of the Participatory Governance Model that there is a complementary relationship between the participation of the SDC/SDA in acquiring the teaching as well as the learning resources and the academic performance of learners. Thus, the study concluded that decentralization policy implementation was the major driving force in strengthening efficiency and accountability of resources and results

The efficacy of education decentralisation policy in Zimbabe: a case of Kadoma district

The study focused on the efficacy of the democratic education decentralization policy. The study focused on the efficacy of the democratic education decentralization policy implementation of the four schools of Kadoma District in Zimbabwe. The thesis reviewed literature and discussed the concept of the democratic education decentralization policy implementation and how this has been practiced in Zimbabwe. The theoretical basis of democratic education decentralization policies were outlined and the argument for and against the policy discussed. Thus the dissertation explored the concept of education decentralization policy with specific reference to the notions of democratization and participation in Zimbabwe. Besides the qualitative and the quantitative research methods employed, the study was complemented by the observation on the ground and document analysis. The thesis unearthed that; the democratic education decentralization policy is characterized by some successes and problems during implementation of the policy as indicated by the paucity of the teaching and learning resources. The research findings revealed that, there is prevalence of poor learning outcomes at ‘O’ level in schools; the SDCs/SDAs are underutilized sources of school development because they are not fully empowered by the education system since they had a minimum role in participating towards the implementation of the policy in order to acquire the teaching and learning resources at the schools in Kadoma District. The above findings long-established the view held by critical theorists of the Participatory Governance Model that there is a complementary relationship between the participation of the SDC/SDA in acquiring the teaching as well as the learning resources and the academic performance of learners. Thus, the study concluded that decentralization policy implementation was the major driving force in strengthening efficiency and accountability of resources and results.mplementation of the four schools of Kadoma District in Zimbabwe. The thesis reviewed literature and discussed the concept of the democratic education decentralization policy implementation and how this has been practiced in Zimbabwe. The theoretical basis of democratic education decentralization policies were outlined and the argument for and against the policy discussed. Thus the dissertation explored the concept of education decentralization policy with specific reference to the notions of democratization and participation in Zimbabwe. Besides the qualitative and the quantitative research methods employed, the study was complemented by the observation on the ground and document analysis. The thesis unearthed that; the democratic education decentralization policy is characterized by some successes and problems during implementation of the policy as indicated by the paucity of the teaching and learning resources. The research findings revealed that, there is prevalence of poor learning outcomes at ‘O’ level in schools; the SDCs/SDAs are underutilized sources of school development because they are not fully empowered by the education system since they had a minimum role in participating towards the implementation of the policy in order to acquire the teaching and learning resources at the schools in Kadoma District. The above findings long-established the view held by critical theorists of the Participatory Governance Model that there is a complementary relationship between the participation of the SDC/SDA in acquiring the teaching as well as the learning resources and the academic performance of learners. Thus, the study concluded that decentralization policy implementation was the major driving force in strengthening efficiency and accountability of resources and results