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Functional programming and security

  • Authors: Motara, Yusuf, M
  • Date: 2012
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/428985 , vital:72551 , https://doi.org/10.48550/arXiv.1201.5728
  • Description: This paper analyses the security contribution of typical functional-language features by examining them in the light of accepted information security principles. Imperative and functional code are compared to illustrate various cases. In conclusion, there may be an excellent case for the use of functional languages on the grounds of better security; however, empirical research should be done to validate this possibility.
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  • Date Issued: 2012

Futures studies for the southern African region : ‘from Africa’ not ‘on Africa’

  • Authors: Fox, Roddy C , Rowntree, Kate M , Kaskinen, J
  • Date: 2012
  • Language: English
  • Type: Conference paper
  • Identifier: vital:6668 , http://hdl.handle.net/10962/d1006685
  • Description: Futures studies is well established in the Nordic region and its history can be readily charted, but in Africa it barely exists in an institutional form and its evolution and impact is little known or understood. The first two sections of our paper briefly examine the history of futures studies, spending most attention on the African experience. We go on to show that the Higher Education landscape in the Southern African Development Community (SADC) region is very different to that in the Nordic region. Recent futures reports present forecasts and scenarios that show a differentiated Higher Education landscape in the SADC; there are few Higher Education Institutions (HEIs) and even the most optimistic forecasts show that the region as a whole will not meet the international enrollment norm of 30% by 2050. The last part of the paper examines our experience of collaboration with Finland and its well developed linkages between state and Universities. One outcome of three years of collaboration from 2007 to 2009 between two SANORD members, the Finland Futures Research Centre (now a part of the University of Turku) and Rhodes University, was a proposal to develop a multi-disciplinary, inter-institutional futures studies program intended to help Africa find its own voice in futures studies. The final part of our presentation reflects on the unsuccessful experiences that we have had to date in finding funding. We conclude by asking whether our experience can be seen as highlighting some of the challenges SANORD may be positioned to overcome if the SADC region’s HEIs are to achieve the Knowledge Village scenario and begin to match their Nordic counterparts.
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  • Date Issued: 2012

Games as communication: an analysis of advertising in South Africa

  • Authors: Wright, Bianca Maria-Teresa
  • Date: 2012
  • Subjects: Internet advertising , Branding (Marketing)
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: vital:8417 , http://hdl.handle.net/10948/d1012929
  • Description: Games as a form of communication have been examined by academics in the fields of game studies, narratology and media studies, among others, but the use of games to communicate advertising messages has not been adequately explored within the South African context. The study sought to investigate the phenomenon of advergaming, purpose-built games designed to communicate an advertising message, in South Africa, and to develop a model for the use of advergaming as a viral marketing tool in this context. Using a hybrid approach, the study examined the way that advertising agencies currently use advergames as well as the effectiveness of advergaming as a means to communicate a message. The study presents the results of a national survey of advertising agencies in South Africa, a content analysis of existing advergames and an analysis of three semi-structured group interview experiments conducted using selected advergames. The findings point to the potential of advergaming as a message communication tool, but also highlight the challenges that may hamper the widespread use of advergaming in South Africa. It proposes the use of the mobile environment as a means to reach a wider South African audience and in that way, overcome some of the obstacles to advergaming adoption. In addition, the results identify aspects of advergames that seem to correlate with the effectiveness of message communication.
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  • Date Issued: 2012

Gaze behaviour patterns of under 19 level Rugby union players during one-on-one defensive play

  • Authors: Raffan, Ryan Phillip
  • Date: 2012
  • Subjects: Rugby football injuries -- Prevention , Visual perception
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/8372 , vital:26350
  • Description: The aim of this study was to describe and compare the gaze behaviour patterns of expert and near expert under 19 level rugby union players during one-on-one defensive play. Gaze characteristics such as the areas of interest visited, the number of fixations, the duration of each fixation, the starting and last fixations; and the order of fixations adopted were used to achieve the aim of the study. In addition, biographical data, including sporting and vision history, were collected. Data of the two groups were described and compared with statistically and practically significant differences been highlighted. Inferential statistics were used and the following significant levels set: p<.05 for t-tests and Chi-sq'ared - tests while Cohen's d (absolute value) ≥0.20 and Cramér‟s V ≥0.10 were used to determine the practical significance for statistically significant results, respectively. An exploratory and quasi-experimental design was used, in which 81 participants (16 – 19 years of age) were sampled for differences between experts' and near experts' visual-search strategies and gaze behaviour patterns when anticipating the direction of deceptive running skills in rugby union, however, only 68 participants had eye tracker data analyzed due to the strict calibration criteria. The expert players correctly anticipated significantly (t-stat = -3.16, p = .002, d = 0.71) more than the near expert players on average (75.76% compared to 66.46%), and therefore, were less susceptible to deceptive running skills. The near expert players were, however, more aware of their fixation location than expert players. Both expert and near expert players fixated considerably more on the knees and hips than any other area of interest, however expert players had fewer, but longer fixations than near expert players per run with 4.29 ± 1.89 fixations (χ2 = 3.90, p = .048, V = 0.24) of 0.420 ± 0.140 seconds (χ2 = 3.97, p = .046, V = 0.24) compared to 5.34 ± 2.39 fixations of 0.350 ± 0.150 seconds. Both the expert and near expert groups fixated more on the lower body than the upper body on average, however, the near expert players fixated significantly more off the body for all correct runs than the expert players (t-stat = 2.17, p = .034, d = 0.53). The expert players start fixating more on the knees at the start of each trial, whereas the near expert players start fixating more on the knees and hips, and considerably off-target. The expert players fixate significantly more on the knees (t-stat = -2.56, p = .013, d = 0.63) at the end of each trial than the near expert players on average, whereas the near expert players fixate more on the hips. The orders of fixation did not yield any discernable patterns between expert and near expert players for correctly anticipated runs. Experts exhibit superior visual-search strategies and gaze behaviour control, presumably using the top-down approach, to successfully anticipate an opponent's intended direction. This information could help coaches teach perceptual tackling skills to enhance motor learning and performance.
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  • Date Issued: 2012

Gender equality in decision-making processes: the case of the Zimbabwean cabinet

  • Authors: Muzvidziwa, Itai
  • Date: 2012
  • Subjects: Women cabinet officers -- Zimbabwe , Sex role -- Political aspects -- Zimbabwe , Sex discrimination – Zimbabwe , Women's rights –- Zimbabwe
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:9133 , http://hdl.handle.net/10948/d1018649
  • Description: Although Zimbabwe is a signatory to various regional and international conventions, treatises, declarations and protocols that seek to promote and create an environment conducive the attainment of gender equality, despite all these commitments, the Zimbabwean Government still lags behind in the area of political participation of women. This study was done to investigate gender equality and the level of participation in governmental decision making processes with specific reference to the cabinet of Zimbabwe. The subject for discussion was traced back to 1980 when Zimbabwe gained its independence and the researcher aimed to ascertain whether there was any significant improvement in terms of women’s participation in governmental decision-making processes and structures. The study also unravelled reasons why women have been at the peripherals of decision- making in cabinet. The study also brought out and evaluated the strategies used by the government of Zimbabwe in managing a gender-sensitive working environment and the legislation that has been put in place to guide the process. At the same time an evaluation was done among the respondents to ascertain the strengths and weaknesses of the strategies identified. Political parties were also included in the process since women who find their way into parliament do so using the tickets of their respective political parties. The political parties have a role to play since they have their respective constitutions in gender sensitive issues and it remains to be seen if they are implementing this which would result in identifying the numbers of women who are in the cabinet. The study is of significance to the Zimbabwean situation at the moment as the country is in the process of drafting a new constitution. The current Constitution in its Section 23 which provides for “protection from discrimination on the grounds of race, tribe, political opinion or physical disability of the persons concerned it is not clear as to what form of representation or position women should occupy in politics and decision-making positions. Given the above research analysis it is possible to conclude that indeed women have an impact on decision making in cabinet. The findings show the impact of considering the value of women in decision-making bodies as they spearheading development in their respective wards and the nation at large. Women were also viewed as decision makers who would contribute in the development of the nation just as much as men are assumed to do. The empowerment of women legislators and the aspiring candidates is a process that has a long way to go to ensure gender equality in governmental decision making processes but it is a necessary process.
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  • Date Issued: 2012

Gender Policy: discussion document 27-29 March 2012

  • Authors: Congress of South African Trade Unions (COSATU)
  • Date: 2012
  • Subjects: Uncatalogued
  • Language: English
  • Type: book , text
  • Identifier: http://hdl.handle.net/10962/68759 , vital:29312
  • Description: The Gender policy draws together existing COSATU resolutions into a coherent document, while further enriching these resolutions. This document aims to combine the vision and principles that we aspire towards, with practical relations in the working workplace and economy, in trade unions and in broader society. The issue of gender equality has been on our agenda since the formation of COSATU. However, we require a policy framework to guide our struggles to transform gender relations in the current period. It is therefore important that we reflect on progress in taking forward the vision and programmes adopted on several Congresses since COSATU inception. In broad terms, progress to realise these resolutions has been uneven and varies between affiliates. COSATU and its affiliates are guided by a vision of a society free of sexism, racism, class exploitation, and other forms of oppression. We envisage a future where women participate equally in the economy and society without barriers, and where women are emancipated from all forms of oppression in the household, the workplace and in broader society. We have a vision of a trade union movement as a home for women workers. This policy document was debated and adopted and the National Gender Conference (held on 5-7 July 2000). It is tabled at Congress for discussion and adoption. Once it has been adopted by the Congress all affiliates will have to give expression to this broad framework in their own policies.
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  • Date Issued: 2012

Generating guidance on public preferences for the location of wind turbine farms in the Eastern Cape

  • Authors: Hosking, Jessica Lee
  • Date: 2012
  • Subjects: Power resources -- South Africa -- Eastern Cape , Energy industries -- South Africa -- Eastern Cape , Wind power plants -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:8989 , http://hdl.handle.net/10948/d1009439 , Power resources -- South Africa -- Eastern Cape , Energy industries -- South Africa -- Eastern Cape , Wind power plants -- South Africa -- Eastern Cape
  • Description: There is consensus that Eskom, South Africa’s main energy supplier, needs to expand its energy generating capacity in order to satisfy the growing demand for electricity, but there is less agreement on how it should do this. The existing supply is heavily reliant on thermal generation using coal, but the combustion of fossil fuels for electricity generation may contribute to climate change because it causes harmful greenhouse gases to be emitted into the atmosphere. This emission is something South Africa has committed itself to reducing. One way of achieving this is by the adoption of cleaner technologies for energy generation. One of these technologies is harnessing wind energy. The problem with harnessing wind energy is where to locate the turbines to harness the wind because these turbines ‘industrialise’ the environment in which they are located. They are a source of increased noise, a visual disturbance, cause increased instances of bird and bat mortality and the destruction of flora or the naturalness of the landscape in the areas in which they are located. The residents located near wind farm developments are most negatively affected and bear the greatest cost in this regard. A proper social appraisal of wind turbine projects would have to take this cost into account. Before such developments are approved there should be an assessment made of the impact on the residents, these impacts should be incorporated into the cost-benefit analysis. The negatively affected residents should also be compensated. The objective of this study was not to undertake a cost-benefit analysis of such a wind farm proposal, but to estimate the negative external cost imposed on nearby residents of such an industry, and thereby calculate appropriate compensation to be paid to these residents. Quantifying preferences for proposed, but not-yet developed, wind farms may be done by applying non-market valuation techniques, e.g. through one of the stated preference methodologies, such as a discrete choice experiment. The selected study site for providing guidance was one where Red Cap Investments Pty (Ltd) has proposed the development of a wind farm - in the Kouga local municipality. The basis for drawing conclusions was the analysis of the response samples of two groups of Kouga residents, distinguished by socio economic status; 270 from each group, 540 in total. The methodology applied to analyse the responses was a discrete choice experiment. The questionnaire administered included attitude, knowledge and demographic questions as well as a choice experiment section. The choice experiment section of the questionnaire required that the respondents choose between two different hypothetical onshore wind energy development scenarios and a status quo option. The hypothetical scenarios comprised different levels of wind farm attributes. The attributes included in the experiment were determined by international studies and focus group meetings. These attributes were: distance between the wind turbines and residential area, clustering of the turbines (job opportunities created by the wind farm development for underprivileged respondent group), number of turbines and subsidy allocated to each household. Three different choice experiment models were estimated for each socio-economic group: a conditional logit (CL), nested logit (NL) and a random parameters logit (RPL) model. It was found that, in the affluent respondent group, the simpler CL model provided the best fit. In the underprivileged respondent group, the RPL model, with the number of jobs created by the wind farm project as a random parameter1, explained by the gender of the respondent, provided the best fit. The estimated models identified distance as an important factor in both sampled respondent groups. Both respondent groups preferred that the wind farm be located further away from their residential areas. In addition to distance, the underprivileged respondent group also valued new job opportunities as an important determinant of choice. The affluent respondent group were very sensitive to densely clustered turbines but were almost indifferent between two of the effects coded levels of the clustering attribute “moderately close together” and “widely spaced apart”. Welfare estimates for the significant attributes in each socio-economic group were computed from the best fit models. Table 1 shows the resulting willingness to accept (WTA) compensation measures for distance in both socio-economic respondent groups.
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  • Date Issued: 2012

Genetic algorithm for Artificial Neural Network training for the purpose of Automated Part Recognition

  • Authors: Buys, Stefan
  • Date: 2012
  • Subjects: Genetic algorithms , Software architecture
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:9648 , http://hdl.handle.net/10948/d1008356 , Genetic algorithms , Software architecture
  • Description: Object or part recognition is of major interest in industrial environments. Current methods implement expensive camera based solutions. There is a need for a cost effective alternative to be developed. One of the proposed methods is to overcome the hardware, camera, problem by implementing a software solution. Artificial Neural Networks (ANN) are to be used as the underlying intelligent software as they have high tolerance for noise and have the ability to generalize. A colleague has implemented a basic ANN based system comprising of an ANN and three cost effective laser distance sensors. However, the system is only able to identify 3 different parts and needed hard coding changes made by trial and error. This is not practical for industrial use in a production environment where there are a large quantity of different parts to be identified that change relatively regularly. The ability to easily train more parts is required. Difficulties associated with traditional mathematically guided training methods are discussed, which leads to the development of a Genetic Algorithm (GA) based evolutionary training method that overcomes these difficulties and makes accurate part recognition possible. An ANN hybridised with GA training is introduced and a general solution encoding scheme which is used to encode the required ANN connection weights. Experimental tests were performed in order to determine the ideal GA performance and control parameters as studies have indicated that different GA control parameters can lead to large differences in training accuracy. After performing these tests, the training accuracy was analyzed by investigation into GA performance as well as hardware based part recognition performance. This analysis identified the ideal GA control parameters when training an ANN for the purpose of part recognition and showed that the ANN generally trained well and could generalize well on data not presented to it during training.
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  • Date Issued: 2012

Geo-spatial autocorrelation as a metric for the detection of fast-flux botnet domains

  • Authors: Stalmans, Etienne , Hunter, Samuel O , Irwin, Barry V W
  • Date: 2012
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/429799 , vital:72640 , 10.1109/ISSA.2012.6320433
  • Description: Botnets consist of thousands of hosts infected with malware. Botnet owners communicate with these hosts using Command and Control (C2) servers. These C2 servers are usually infected hosts which the botnet owners do not have physical access to. For this reason botnets can be shut down by taking over or blocking the C2 servers. Botnet owners have employed numerous shutdown avoidance techniques. One of these techniques, DNS Fast-Flux, relies on rapidly changing address records. The addresses returned by the Fast-Flux DNS servers consist of geographically widely distributed hosts. The distributed nature of Fast-Flux botnets differs from legitimate domains, which tend to have geographically clustered server locations. This paper examines the use of spatial autocorrelation techniques based on the geographic distribution of domain servers to detect Fast-Flux domains. Moran's I and Geary's C are used to produce classifiers using multiple geographic co-ordinate systems to produce efficient and accurate results. It is shown how Fast-Flux domains can be detected reliably while only a small percentage of false positives are produced.
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  • Date Issued: 2012

Government-sponsored community development projects as poverty alleviation tools: evidence from Mdantsane, East London

  • Authors: Gedze, Ntombebhongo
  • Date: 2012
  • Subjects: Community development -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Agricultural development projects -- South Africa -- Eastern Cape , Agriculture and state -- South Africa -- Eastern Cape , Eastern Cape -- South Africa , Poverty alleviation , Community participation , Mdantsane Township
  • Language: English
  • Type: Thesis , Masters , M Soc Sc (Rural Development)
  • Identifier: vital:11948 , http://hdl.handle.net/10353/d1005995 , Community development -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Agricultural development projects -- South Africa -- Eastern Cape , Agriculture and state -- South Africa -- Eastern Cape , Eastern Cape -- South Africa , Poverty alleviation , Community participation , Mdantsane Township
  • Description: The study investigates whether government-sponsored community development projects in the township of Mdantsane, Buffalo City Metropolitan Municipality, South Africa, have achieved the intended goal of alleviating poverty among the beneficiaries. The specific outcomes of poverty alleviation are: improved income, acquisition of new skills, reduced dependence on welfare grants. Four urban farming projects were selected, namely: Buffalo City Organic Producers, Sakhisizwe Nursery, Lusindiso Farmer’s Trading Co-operative and Mbombela Co-operative. Focus group discussions and a mini survey were conducted with project beneficiaries, while relevant government officials were interviewed. Conceptual insights were drawn from community development theory. The findings showed that the broader context within which the projects occurred was characterised by a pro-poor social policy, relative availability of resources with which to translate it into action, and a measure of entrepreneurial potential amongst community members. However, while one of the projects showed some promise (in the sense that beneficiaries acquired new skills and had a generally positive attitude despite not enjoying any improved income status), all the others appeared doomed and trapped in dynamics such as: excessive government control of the management of the initiatives, ineffective project monitoring, and the mischaracterisation of the initiatives by both the government and the beneficiaries. A distorted sense of ownership and perverse community participation seemed to prevail, which in turn robbed the initiatives of their poverty alleviation potential. The study thus concluded that specific benefactor-beneficiary dynamics are crucial for the success of a given anti-poverty intervention. A robust pro-poor social policy, availability of resources with which to translate it into action, and local entrepreneurial potential do not in themselves bring about success; they must operate in a certain way and be undergirded by certain principles for them to become a powerful mechanism for alleviating poverty. It is against this background that the researcher offers some recommendations.
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  • Date Issued: 2012

GPF : a framework for general packet classification on GPU co-processors

  • Authors: Nottingham, Alastair
  • Date: 2012
  • Subjects: Graphics processing units , Coprocessors , Computer network protocols , Computer networks -- Security measures , NVIDIA Corporation
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4661 , http://hdl.handle.net/10962/d1006662 , Graphics processing units , Coprocessors , Computer network protocols , Computer networks -- Security measures , NVIDIA Corporation
  • Description: This thesis explores the design and experimental implementation of GPF, a novel protocol-independent, multi-match packet classification framework. This framework is targeted and optimised for flexible, efficient execution on NVIDIA GPU platforms through the CUDA API, but should not be difficult to port to other platforms, such as OpenCL, in the future. GPF was conceived and developed in order to accelerate classification of large packet capture files, such as those collected by Network Telescopes. It uses a multiphase SIMD classification process which exploits both the parallelism of packet sets and the redundancy in filter programs, in order to classify packet captures against multiple filters at extremely high rates. The resultant framework - comprised of classification, compilation and buffering components - efficiently leverages GPU resources to classify arbitrary protocols, and return multiple filter results for each packet. The classification functions described were verified and evaluated by testing an experimental prototype implementation against several filter programs, of varying complexity, on devices from three GPU platform generations. In addition to the significant speedup achieved in processing results, analysis indicates that the prototype classification functions perform predictably, and scale linearly with respect to both packet count and filter complexity. Furthermore, classification throughput (packets/s) remained essentially constant regardless of the underlying packet data, and thus the effective data rate when classifying a particular filter was heavily influenced by the average size of packets in the processed capture. For example: in the trivial case of classifying all IPv4 packets ranging in size from 70 bytes to 1KB, the observed data rate achieved by the GPU classification kernels ranged from 60Gbps to 900Gbps on a GTX 275, and from 220Gbps to 3.3Tbps on a GTX 480. In the less trivial case of identifying all ARP, TCP, UDP and ICMP packets for both IPv4 and IPv6 protocols, the effective data rates ranged from 15Gbps to 220Gbps (GTX 275), and from 50Gbps to 740Gbps (GTX 480), for 70B and 1KB packets respectively. , LaTeX with hyperref package
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  • Date Issued: 2012

Gravitational entropy and thermodynamics away from the horizon

  • Authors: Brustein, R , Medved, A J M
  • Date: 2012
  • Language: English
  • Type: Article
  • Identifier: vital:6818 , http://hdl.handle.net/10962/d1004328
  • Description: We define, by an integral of geometric quantities over a spherical shell of arbitrary radius, an invariant gravitational entropy. This definition relies on defining a gravitational energy and pressure, and it reduces at the horizon of both black branes and black holes to Wald's Noether charge entropy. We support the thermodynamic interpretation of the proposed entropy by showing that, for some cases, the field theory duals of the entropy, energy and pressure are the same as the corresponding quantities in the field theory. In this context, the Einstein equations are equivalent to the field theory thermodynamic relation TdS=dE+PdV supplemented by an equation of state
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  • Date Issued: 2012

Graviton n-point functions for UV-complete theories in Anti-de Sitter space

  • Authors: Brustein, R , Medved, A J M
  • Date: 2012
  • Language: English
  • Type: text , Article
  • Identifier: vital:6820 , http://hdl.handle.net/10962/d1004427
  • Description: We calculate graviton n-point functions in an anti-de Sitter black brane background for effective gravity theories whose linearized equations of motion have at most two time derivatives. We compare the n-point functions in Einstein gravity to those in theories whose leading correction is quadratic in the Riemann tensor. The comparison is made for any number of gravitons and for all physical graviton modes in a kinematic region for which the leading correction can significantly modify the Einstein result. We find that the n-point functions of Einstein gravity depend on at most a single angle, whereas those of the corrected theories may depend on two angles. For the four-point functions, Einstein gravity exhibits linear dependence on the Mandelstam variable s versus a quadratic dependence on s for the corrected theory.
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  • Date Issued: 2012

Green business and environmental issues: family versus non-family business

  • Authors: Grobler, Marthinus Petrus Johannes
  • Date: 2012
  • Subjects: Environmental impact analysis -- South Africa , Family-owned business enterprises
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: vital:8636 , http://hdl.handle.net/10948/d1008058 , Environmental impact analysis -- South Africa , Family-owned business enterprises
  • Description: The aim of the study was to understand whether family businesses and non-family business differ from one another regarding green business and environmental issues. Green business issues are of global importance for the continued existence of business within the world. Businesses do not exist in isolation but within the context of the environment within which they function. Business has an impact on the environment and the environment has an impact on business. Furthermore, family businesses constitute a large part of the world economy and estimates range from 60-90 percent of GDP contributed by family businesses. In the South African context family businesses also form a significant part of the business environment. A literature study was conducted. The study identified five factors and considered each of these factors in the study. The five factors are: Green Business; Values; Stewardship; Succession; and, Stakeholders. In addition to a literature, primary research was conducted and data were collected by means of a questionnaire that collected data on the factors identified as well as some biographical information, including race, age and the sectors in which the respondents operated. The study’s findings correspond with the literature study, although no clear difference was found between family business and non-family business relating to green business and environmental issues. Family businesses do however believe that they are stewards of the environment and need to care for the environment.
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  • Date Issued: 2012

Growth and characterization of ZnO nanorods using chemical bath deposition

  • Authors: Urgessa, Zelalem Nigussa
  • Date: 2012
  • Subjects: Zinc oxide , Photoluminescence , Semiconductor nanocrystals , Semiconductors -- Materials , Chemical reactions
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10559 , http://hdl.handle.net/10948/d1021124 , http://hdl.handle.net/10948/d1021119
  • Description: Semiconductor devices are commonplace in every household. One application of semiconductors in particular, namely solid state lighting technology, is destined for a bright future. To this end, ZnO nanostructures have gained substantial interest in the research community, in part because of its requisite large direct band gap. Furthermore, the stability of the exciton (binding energy 60 meV) in this material, can lead to lasing action based on exciton recombination and possibly exciton interaction, even above room temperature. Therefore, it is very important to realize controllable growth of ZnO nanostructures and investigate their properties. The main motivation for this thesis is not only to successfully realize the controllable growth of ZnO nanorods, but also to investigate the structure, optical and electrical properties in detail by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy (steady state and time resolved) and X-ray diffraction (XRD). Furthermore, strong rectification in the ZnO/p-Si heterojunction is demonstrated. Nanorods have been successfully synthesized on silicon by a two-step process, involving the pre-coating of the substrate by a seed layer, followed by the chemical bath deposition of the nanorods. ZnO seed layers with particle sizes of about 5 nm are achieved by the thermal decomposition of zinc acetate dihydrate dissolved in ethanol. The effects of the seed layer density on the distribution, alignment and uniformity of subsequently grown nanorods were studied. The aspect ratio, orientation and distribution of nanorods are shown to be well controlled through adjusting the density of the ZnO nanoparticles pre-coated onto the substrates. It is shown that the seed layer is a prerequisite for the growth of well aligned ZnO nanorods on lattice mismatched Si substrate. The influence of various nanorod growth parameters on the morphology, optical and electrical properties of the nanorods were also systematically studied. These include the oxygen to zinc molar ratio, the pH of the growth solution, the concentration of the reactants, the growth temperature and growth time, different hydroxide precursors and the addition of surface passivating agents to the growth solution. By controlling these xii parameters different architectures of nanostructures, like spherical particles, well aligned nanorods, nanoflowers and thin films of different thicknesses are demonstrated. A possible growth mechanism for ZnO nanostructures in solution is proposed. XRD indicated that all the as-grown nanostructures produced above 45 C crystallize in the wurtzite structure and post growth annealing does not significantly enhance the crystalline quality of the material. In material grown at lower temperature, traces of zinc hydroxide were observed. The optical quality of the nanostructures was investigated using both steady-state PL and time-resolved (TR) PL from 4 K to room temperature. In the case of as-grown samples, both UV and defect related emissions have been observed for all nanostructures. The effect of post-growth annealing on the optical quality of the nanostructures was carefully examined. The effect of annealing in different atmospheres was also investigated. Regardless of the annealing environment annealing at a temperature as low as 300 C enhances the UV emission and suppresses defect related deep level emission. However, annealing above 500 C is required to out-diffuse hydrogen, the presence of which is deduced from the I4 line in the low temperature PL spectra of ZnO. TRPL was utilized to investigate lifetime decay profiles of nanorods upon different post growth treatments. The bound exciton lifetime strongly depends on the post-growth annealing temperature: the PL decay time is much faster for as grown rods, confirming the domination of surface assisted recombination. In general, the PL analysis showed that the PL of nanorods have the same characteristics as that of bulk ZnO, except for the stronger contribution from surface related bound excitons in the former case. Surface adsorbed impurities causing depletion and band bending in the near surface region is implied from both time resolved and steady state PL. Finally, although strong rectification in the ZnO/p-Si heterojunction is illustrated, no electroluminescence has been achieved. This is explained in terms of the band offset between ZnO and Si and interfacial states. Different schemes are proposed to improve the performance of ZnO/Si heterojunction light emitting devices.
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  • Date Issued: 2012

Guidelines for the adaptation of the TETRA educational programme at Nelson Mandela Metropolitan University to address human behavioural issues

  • Authors: Fouche Nico Pieter
  • Date: 2012
  • Subjects: Nelson Mandela Metropolitan University -- Communication systems , Human behavior
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:9801 , http://hdl.handle.net/10948/d1012248 , Nelson Mandela Metropolitan University -- Communication systems , Human behavior
  • Description: Information is a vitally important asset to organizations and the information should be protected to sustain the value it provides to the organization. Information is transferred via different mediums in these organizations. An example would be Terrestrial Trunked Radio or TETRA, which is utilized within organizations to provide a technically very secure form of digital radio communication. TETRA is a communications technology that is currently being successfully used throughout the world for secure, reliable and robust critical communication. TETRA is used by Public Safety and Security (PSS) and transportation sectors, amongst others. PSS includes police officers, fire marshals and emergency medical units who require protected and accurate information that could influence decisions that could make difference between life and death. The TETRA educational programme offered by the TETRA Academy at the Nelson Mandela Metropolitan University (NMMU), educates TETRA users in various aspects of the TETRA standard. TETRA is viewed as a technically very secure communication standard, as it utilizes security features such as mutual authentication, air interface encryption, end-to-end encryption, jamming detection and ambience listening, amongst other security techniques to ensure that the information traversing through the network is kept secure. The TETRA educational programme material includes many physical and technical controls to assist TETRA users in protecting information. However, to what extent does the TETRA educational programme address operational controls? Operational controls address what is often referred to as the weakest link in information security – human behavioural issues. Humans can be exploited through human manipulation attacks, which include social engineering and bribery. Therefore, this study argues towards adapting the TETRA educational programme offered at the NMMU to address these human behavioural issues.
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  • Date Issued: 2012

Guidelines for the design of a mobile phone application for deaf people

  • Authors: Yeratziotis, George
  • Date: 2012
  • Subjects: Mobile communication systems -- Design and construction , Deaf -- Means of communication
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:9750 , http://hdl.handle.net/10948/d1007925 , Mobile communication systems -- Design and construction , Deaf -- Means of communication
  • Description: Deaf people in South Africa are no longer a minority group and their needs regarding communication and interaction must therefore be taken into consideration. This demographic does not communicate and interact in the same way as hearing people, which means that any existing usability or accessibility guidelines do not apply. As a result, Deaf people do not have access to information in the same way that a hearing person does. Providing proper access to Information and Communications Technology services, which meet their particular needs, will help the hearing impaired to better integrate into society. The importance of demolishing the communication barrier between the hearing and the hearing impaired is very important. Many people assume that sign language is somehow based on oral language. However, this is not the case. Sign languages are natural visual-spatial languages, and form a contrast with spoken languages which are auditory-vocal based. Acknowledging this fact in 2008, the South African Sign Language Policy Implementation Conference together with several governmental bodies suggested that South African Sign Language should become recognized as the 12th official language of South Africa. Due to the fact that cell phone technology continues to evolve, it will remain a tool of communication upon which Deaf people heavily rely on. The cell phone fulfils a basic need for everyone, but especially for the Deaf demographic as they rely on the short message system to communicate. Deaf people are currently faced with a lack of appropriate mobile phone applications, which would allow them to communicate with hearing as well as deaf people. The primary objective of this research was therefore to make mobile technology equally accessible meaning usable to members of the Deaf demographic. The focus of the research was to investigate the communication barrier and a range of variables that can influence the deaf user’s experience. Topics such as user interface design, usability and interaction were investigated. The outcome of this research was to propose a set of guidelines that, when applied to the design of a website or to phone application accessibility, would ensure communication and interaction from a deaf user. The proposed set of guidelines was then applied to the design of the high fidelity prototype of a mobile phone application. The specific application is a messaging phone application that allows deaf users to communicate with other deaf and hearing users via short message system. A mobile phone application that allows Deaf people to send and receive messages based on the sign language alphabet. The application was named Signchat. Purpose of this was to visibly display how the guidelines were implemented in Signchat. While Signchat’s main purpose is to accommodate the needs of Deaf people, it is also a learning tool and an application that bridges the gap by allowing deaf and hearing users to communicate.
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  • Date Issued: 2012

Guidelines to establish an e-safety awareness in South Africa

  • Authors: De Lange, Mariska
  • Date: 2012
  • Subjects: Internet and children--Safety measures , Internet in education , Online etiquette
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:9747 , http://hdl.handle.net/10948/d1007863 , Internet and children--Safety measures , Internet in education , Online etiquette
  • Description: Information and Communication Technology (ICT) has become an integral part of almost every individual’s life. Although ICT, particularly the Internet, might offer numerous opportunities, individuals should also be aware of the associated risks. Especially with the younger generations who can be seen as being the most vulnerable to online dangers as they are becoming more involved in online activities. Children are utilizing new technologies from an early age and should know how to keep themselves and others safe whilst accessing the Internet. However, most of them do not have the required knowledge and expertise to protect themselves. This is because, under most circumstances, the parents do not understand their children’s online behaviours and activities and are, therefore, unable to teach their children how to utilize it safe and responsibly. A school can be seen as the perfect place to teach children safe online behaviours. However, there is currently a definite lack of e-Safety in South African schools, because no e-Safety policies are in place and there is little or nothing in curricula with regards to e-Safety. This can lead to additional concerns. The primary objective of this research study is, therefore, to develop, motivate and verify a framework that might contribute towards the development of an e-Safety culture. This e-Safety culture should allow individuals to adapt their behavior towards the secure utilization of ICT. However, for the purpose of this research study, the focus will primarily be on learners from primary and secondary schools.
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  • Date Issued: 2012

Guy Butler’s South Africanism: ‘Being present where you are’

  • Authors: Wright, Laurence
  • Date: 2012
  • Language: English
  • Type: text , article
  • Identifier: vital:7069 , http://hdl.handle.net/10962/d1007460 , https://doi.org/10.1080/10131752.2012.730182
  • Description: preprint , A peer-reviewed lecture delivered at Rhodes University on the occasion of the presentation to Professor Wright of the English Academy's Gold Medal, 16 November 2011. Guy Butler (1918-2001) has been gone some ten years. This lecture sets out to illuminate the thinking behind his important role in South Africa's national life. The institutions he created continue to make vital cultural contributions in South Africa's efforts to make sense of its own complex historical make-up, working towards a happier, richer, and more equal future. However, despite what he achieved, there is little surety that today the rationale informing his massive effort to foster processes of artistic and cultural endeavour has been appreciated or accurately understood.
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  • Date Issued: 2012

Haul Music : transnationalism and musical performance in the Saharaui refugee camps of Tindouf, Algeria

  • Authors: Gimenez Amoros, Luis
  • Date: 2012
  • Subjects: Bedouins -- Music -- Research Sahrawi (African people) -- Migrations Social change -- Arab countries Arab countries -- Social life and customs Civilization, Arab
  • Language: English
  • Type: Thesis , Masters , MMus
  • Identifier: vital:2637 , http://hdl.handle.net/10962/d1002302
  • Description: The thesis presents ethnographic data and musical analysis (in the form of transcriptions) of Haul music which is the music style performed by Bedouin societies in Trab el Bidan region (Mauritania, Western Sahara, northern Mali, southern Algeria and northern Morocco). It is based on field research undertaken in Algeria in 2004-05 in the refugee camps of Tindouf, Algeria, where Saharaui people (a Bedouin society)live in exile. This research is unique and original as Haul has not, until now, been explored in depth by any scholar. My research on Haul reveals that the changes in Saharaui music in the refugee camps of Tindouf reflect changes in the musical traditions of Bedouin societies as whole; changes that can be traced to the revolution which occurred in Western Sahara in 1975, and changes that are a result of the migrations and life in exile that followed. I argue that these changes occurred due to the transnational experiences undergone by Saharaui people in their forced exile (caused by the Moroccan state) from their homeland in Western Sahara to Algeria. Further, I assert that the invocation of memory in Bedouin musical styles is evidence of past musical practices being retained in contemporary Haul performance, although other musical changes are similarly in progress.
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  • Date Issued: 2012
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