Made available in DSpace on 2014-10-09T12:38:13Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:53Z (GMT). No. of bitstreams: 1 05656.pdf: 8838719 bytes, checksum: f09f7a8c625f6de1d6d461eee9e5bbdb (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Voltage-Sourced Converter High Voltage Direct Current (VSC-HVDC) transmission technology has received great interest and experienced rapid development worldwide because of its compact size, ability to connect two asynchronous AC systems and ability to connect to weak AC grids. It is expected that VSC-HVDC will play a significant role in future power transmission networks. Multi-Terminal Direct Current (MTDC) networks are even being established based on VSC-HVDC and these have great potential to support conventional AC transmission networks. However, such DC networks are vulnerable to any DC side short-circuit fault. DC protection issues must be tackled to enable the development of MTDC networks. This thesis conducts some of the underpinning research for such DC protection studies. As a first step to conduct the protection study, a detailed four-terminal VSC-HVDC system is developed in PSCAD/EMTDC, which consists of both two-level converters and MMC devices. Based on this high fidelity four-terminal system model, a thorough analysis is conducted for the two-level converter and the MMC systems under different fault scenarios. Based on this, a basic understanding of the converter systems' natural responses to these fault scenarios is obtained. Apart from using a DC circuit breaker to isolate a DC fault, there may be other devices which could potentially be used for DC protection. After the fault analysis, a study is conducted to search for any other DC protection equipment which could help the DC breaker isolate a DC fault. Different types of fault current limiters (FCLs) are reviewed and compared. It is found that the resistive type superconducting FCL (SCFCL) has the potential to be usefully employed for DC protection. Next, a DC fault detection and location strategy study is performed. This thesis conducts a detailed study of different DC fault detection and location strategies using a much higher fidelity model than previous studies. After reviewing different fault detection methodologies, it is found that wavelet transforms presently might be the best option for DC protection. The continuous wavelet transform (CWT) is then extensively tested under different DC faults and transient scenarios to prove its robustness, as this method has not been extensively studied in the previous literature. In the end, by using the CWT and placing the SCFCLs in series with DC circuit breakers, the performance of the SCFCLs under a DC side pole-to-pole fault is examined. This study shows that the SCFCL can help reduce the fault current seen by a DC breaker. In the end, a DC system fault recovery study is performed. Different methods are proposed and studied to examine the impact they have on the converter system's DC fault recovery process. A novel bump-less control is proposed to help the system achieve a good fault recovery response.

Pas de résumé / Doctorat en droit / info:eu-repo/semantics/nonPublished

For years, promotional activities in South Africa have been subject to regulation by various industry-specific regulatory bodies, such as inter alia, the Advertising Standards Authority, the Direct Marketing Association of South Africa and the Independent Communications Authority of South Africa. In addition, various, legislative pieces including the Consumer Affairs (Harmful Business Practice) Act 71 of 1988, the Tobacco Products Control Act 83 of 1993, and the Electronic Communications and Transactions Act 25 of 2002 have regulated important aspects pertaining to promotional activities. Following the promulgation of the Consumer Protection Act 68 of 2008 (hereafter referred to as the CPA or the Act) all forms of promotional activities in South Africa are now regulated under this single piece of legislation, or are they? The potential problems that arise from the application of the provisions pertaining to promotional activities in the CPA are the threefold: namely, the possible redundancy of these pre-existing regulatory bodies; the over-regulation of promotional activities in South Africa; and the interplay between the provisions of the CPA, as well as the legislation and Codes pertaining to promotional activities, that have not been repealed by the Act. The investigation into these three major concerns will be conducted with reference to the regulation of promotional activities in terms of other South African statutes and existing Codes. In addition a comparative analysis with the regulation of promotional activities in the United Kingdom will be carried out. / Dissertation (LLM)--University of Pretoria, 2014. / Mercantile Law / unrestricted

The current study originated from the realisation that information security is no longer solely dependent on technology. Information security breaches are often caused by users, most of the time internal to the organisation, who compromise the technology-driven solutions. This interaction between people and the information systems is seemingly the weakest link in information security. A people-oriented approach is needed to address this problem. Incorporating the human element into information security could be done by creating an information security culture. This culture can then focus on the behaviour of users in the information technology environment. The study is therefore principally aimed at making a contribution to information security by addressing information security culture and, for this reason, culminates in the development of an information security culture model and assessment approach. While developing the model, special care was taken to incorporate the behaviour of people in the working environment and hence organisational behaviour coupled with issues concerning information security culture that need to be addressed. An information security culture assessment approach is developed consisting of a questionnaire to assess whether an organisation has an adequate level of information security culture. The assessment approach is illustrated through a case study. Below is an overview of the framework within which the research was conducted: The dissertation consists of four parts. Chapters 1 and 2 constitute Part 1: Introduction and background. Chapter 1 serves as an introduction to the research study by providing the primary motivation for the study and defining the problems and issues to be addressed. In addition, the chapter is devoted to defining a set of standard terms and concepts used throughout the study. The chapter concludes with an overview of the remaining chapters. Chapter 2 gives some background to information security culture and discusses its evolution to date. There is a new trend in information security to incorporate the human element through an information security culture. Information security is divided into two different levels. Level 1 focuses on the human aspects of information security, such as the information security culture, and level 2 incorporates the technical aspects of information security. Part 2: Information security culture model is covered in chapters 3, 4 and 5. In chapter 3, the concept of information security culture is researched. Different perspectives are examined to identify issues that need to be considered when addressing information security culture. A definition of information security culture is constructed based on organisational culture. Chapter 4 is devoted to developing a model that can be used to promote an information security culture. This model incorporates the concept of organisational behaviour as well as the issues identified in chapter 3. Chapter 5 builds upon the information security culture model and aims to identify practical tasks to address in order to implement the model. In Part 3: Assessing information security culture, chapters 6 to 10, attention is given to the assessment of an information security culture, giving management an indication of how adequately the culture is promoted through the model. Chapter 6 considers the use of available approaches such as ISO17799 to aid in promoting and assessing an information security culture. This approach is evaluated against the definition of information security culture and the information security culture model in order to determine whether it could assess information security culture in an acceptable manner. The next four chapters, namely chapters 7 to 10, are devoted to the development of an information security culture assessment approach consisting of four phases. Chapter 7 discusses phase 1. In this phase a questionnaire is developed based on the information security culture model. Chapter 8 uses the information security culture questionnaire as part of a survey in a case study. This case study illustrates phase 2 as well as what information can be obtained through the questionnaire. In chapter 9 the data obtained through the survey is analysed statistically and presented (phase 3). The level of information security culture is then discussed in chapter 10, with interpretations and recommendations to improve the culture (phase 4). Chapter 11 in Part 4: Conclusion serves as a concluding chapter in which the usefulness and limitations of the proposed model and assessment approach are highlighted. The research study culminates in a discussion of those aspects of information security culture that could bear further research. / Prof. J.H.P. Eloff

M.Ing. / This dissertation is intended to make a contribution to the engineering intellectual pool of knowledge by offering a perspective on the subject of software development that encompasses safety (i.e. quality, qualification and reliability). Software development will be examined in light of developments made in recent years in three engineering disciplines: quality, qualification and reliability. These developments will be infused into an established system engineering process currently in use in Denel Dynamics (referred to as ‘the organization’). This dissertation will probe how the concept of software quality is addressed and ensured in the organization. With the aid of current (best) practices and processes; techniques and systems, the author intends to present a different perspective on the development of quality software products from the current view of the organization, by addressing software safety, reliability and cost. The author believes that software quality, with particular emphasis on reliability, if systematically administered in a structured and controlled manner in an organization, will yield products for global markets that are both safe and cost-efficient. In the following chapters, software reliability will be discussed in detail in a quantitative and/or qualitative manner to explain the case presented. It is envisioned that the information collated in this dissertation will be used by all involved in the software product life cycle, such as first-time programme or project managers, programmers and decision makers, to help make informed decisions that will ensure the organization realizes the best return on its investment.

LL.M.

The government identified the small business sector as an important variable in sustainable economic growth and employment creation. The purpose of this study is to determine the impact of minimum wage regulation and employment protection policies on the unemployment statistics of South Africa. Unemployment is an aspect that needs attention to assist with long-term sustainability of growth. The questionnaire was distributed to approximately 20 000 small business owners in South Africa and 1239 responded. Of the 1239 responses, 900 could be used. The research propositions were that employment protection legislation relates to a decrease in job creation and minimum wages relates to higher unemployment. The third proposition is an assumption made in the event that the first two propositions were proved correct. These propositions were proved incorrect. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

No abstract available Copyright / Dissertation (LLM)--University of Pretoria, 2012. / Mercantile Law / unrestricted

No description available.