University of Macau / Faculty of Social Sciences and Humanities / Department of Government and Public Administration

Thesis (doctoral)--Universität Köln, 2008. / Includes bibliographical references (p. 308-344).

The need for smaller and more efficient power supplies steadily grows. Many power supplies incorporate high-frequency dc-to-dc switching converters to meet these demands. Recently, a new class of switching converters has been introduced which can operate at very high frequencies to further reduce size and increase efficiency. They are called quasi-resonant converters. Previously, the dc characteristics of many of these converters had been determined, assuming ideal components and circuit operating conditions. However, as the frequency of operation increases, the circuit behavior becomes less ideal causing changes in the expected characteristics. This is because resistive losses, semiconductor junction capacitances, and other parasitic (undesirable) elements become more pronounced at higher frequencies. This thesis investigates the effects of parasitic elements on the dc characteristics of several zero-current-switched, buck-derived quasi-resonant converters. For the quasi-resonant buck converter, it is demonstrated that for certain operating conditions the dc voltage gain can increase when parasitic losses are increased. Design guidelines are given for maximizing this converter's efficiency. Various forward quasi-resonant topologies are investigated, and the effects of parasitic elements on circuit operation are highlighted. A dc analysis is performed for the secondary-resonance forward converter, which has not previously been analyzed. This converter can operate either in full-wave or half-wave mode. Its dc voltage gain in full-wave mode is less sensitive to load variations than other resonant forward topologies that only operate in half-wave mode. / Master of Science

Waste management systems are created based on a careful balance of interrelated factors, a variety of players, and diverse political, social, and economic landscapes. The purpose of this study is to identify the impacts to waste management caused by limited supply or increased cost of energy. A case study was created based on the Alberta Capital Region using literature review, surveys and interviews to identify how energy is used throughout the various phases of waste management, from collection through to disposal and diversion, and what the factors are that affect the organization and infrastructure selected for the waste management system. The results of this study conclude that there are economic, social, environmental, political, and decision-making impacts related to an energy crisis. In particular, it was concluded that an energy crisis will cause social and economic stresses that will result in organizational and infrastructure changes to waste management.

Historically, the most frequently used energy sources have been those nearest and easiest to consume. Unfortunately, society’s reliance on fossil fuel for power generation has occurred at the expense of the environment, coal being a major contribution to carbon dioxide (CO2) emission. Carbon dioxide is classified as a greenhouse gas (GHG); it contributes to the phenomenon of climate change (Haw & Hughes, 2007, p.1). According to Worrell (2011), industry uses nearly 40 percent of worldwide energy on economic activities. Value chain activities alone contribute almost 37 percent to global GHG. Organisations are socially and ethically required to minimise the carbon footprint of their operations. Reducing energy use makes perfect business sense; it saves money, enhances corporate reputations and helps everyone participate the fight against climate change (Carbon Trust, 2011). Gielen, Newman, and Patel (2008) strongly believe the overall energy and emissions trends can be mitigated through additional energy efficiency measures. However, implementing EnMS will enable organisations to establish systematic approaches and the processes necessary to improve energy performance, including energy efficiency, use and consumption (SANS 50001, 2011). The objective of this paper was to evaluate the current energy management strategy adopted by selected automotive manufacture in Eastern Cape. The research was motivated by the fact that previous researchers have focused more on technological aspects and less of management functions. The research paradigm followed in this paper was qualitative because a case study is used to gain an insight and understanding about more and less successful energy management strategies. In this report, background about the global energy outlook and its significant to economic development, factors behind energy demands, the link to climate change and providing effective energy management principles are covered. The energy management principles covered key elements for delivering successful energy management. Literature highlighted that, senior management commitment is the foundation of good energy management, which is delivered through a formal energy policy and a supporting energy strategy with action plan. High level commitment will provide: Advocacy from senior managers; Visibility of the issues across your organization; Impetus for the organisation to implement energy management; Resources, both human and financial. It will also demonstrate that good energy management is part of your organisation’s mission and as relevant as other management aspects. The empirical study is focused on the characteristics of the current management system and organisational structure employed with its relevant functions. Based on these reference points the paper concludes with recommendations for the case study organisation.

Worldwide energy consumption is estimated to double between 2008 and 2035. Over-dependence on energy imports from a few, often politically unstable countries, and unpredictable oil and gas prices, pushes energy to a critical agenda. While there is an agreement that we need to change the production and consumption of energy, there is still disagreement about the specific changes that are needed and how they can be achieved. The conventional energy plans relying primarily on fossil fuels and nuclear technologies, which are in need of transformation due to limited resources and carbon dioxide emissions. Energy efficiency improvements and renewable energy should play a leading role in the America's energy future. Energy and environmental organizations believe that renewable energy and energy efficiency can meet half of the world's energy needs by 2050. This thesis describes a model that predicts renewable energy portfolios for the Southern portion of the United States, by evaluating multiple renewable energy sources such as solar, wind, hydropower, biomass, and geothermal. The Southern US is divided into three regions: Southwest, South Central, and Southeast, which are chosen given their location and the level of abundance of renewable resources, thereby minimizing inefficiencies and losses associated to the present generation system. A mathematical predictor takes into account variables such as supply/demand, non-renewable/renewable sources, and time. From the results, the Southwest and South Central regions confirm an surplus of renewable electricity by 2050, but the Southeast region does not have enough renewable resources to detach itself from the use of fossil fuels. The South Central region begins producing a surplus of renewable energy in 2014 and reaches an excess amount of 14,552 billion KWh by 2050. This means there will be no need to transfer electricity over long distances, which will increase the overall efficiency of electrical generation.

Thesis submitted in fulfilment of the requirements for the Degree of Master of Technology: Organic Chemistry, Durban University of Technology, 2011. / Malaria, the most prevalent parasitic disease, is considered a neglected disease owing to insufficient research and development in synthesis and therapy worldwide. Therapy failures are frequent and are due to a variety of factors such as the intrinsic characteristics of the disease, conditions of transmission, and the difficult control of spreading through tropical areas. Primary factors are the complexity of the parasite life cycle and the development of drug resistance. Another critical factor is the increasing number of immune-compromised patients that suffer from malaria and human immunodeficiency virus (HIV) co-infections. Most of the drugs currently available to treat malaria are quinoline derivatives modelled on the quinine molecule, found in the bark of Cinchona trees. Over the last 50 years the use of quinine has declined owing to the development of synthetic 4-aminoquinolines such as chloroquine. However, the malaria parasite is rapidly becoming resistant to the drugs currently available. Recently bisquinoline compounds were found more potent than chloroquine against both chloroquine-sensitive and resistant strains of malaria; this improved efficacy and prompted an increased interest in the design of these anti-malarial drugs. Although several synthetic methods are available to synthesise bisquinolines, we report the synthesis of bisquinolines from simple, readily available and cost- effective starting compounds. The synthesis was accomplished in four reaction steps using the Claisen condensation, Vilsmeir-Haack reaction, formation of a Schiff base and thermal cyclization, sequentially. We used a conventional energy source and microwave irradiation for the synthesis, wherever possible, of 2, 4-dichloro-3, 4'-biquinoline and 2, 4-dichloro-7'-methoxy-3, 4'-biquinoline. In the first step, 3-acyl-2, 4-dihydroxyquinoline is synthesised from an equimolar mixture of methyl-2-aminobenzoate and ethyl acetoacetate by microwave irradiation for 3 minutes; the yield is 90 % whereas by 6 hours refluxing the yield is 75 %. This is followed by the synthesis of 3-chloro-3-(2,4-dichloroquinolin-3yl) acrylaldehyde, by combining DMF and POCl3 at 00C to form the electrophile which reacts with 3-acyl-2,4-dihydroxyquinoline under microwave irradiation for 5 minutes; the yield is 65 % whereas by 6 hours refluxing the yield is 50 %. In the next step, several protocols to prepare a Schiff base 3-chloro-3-(2, 4-dichloroquinolin-3-yl) allylidene aniline are investigated with the best yield of 75% obtained by microwave irradiation for 5 minutes. Subsequently three aniline derivatives viz, 4-methoxyaniline, 4-chloroaniline and 4-methylaniline, are used as substrate to prepare 3-chloro-3-(2,4-dichloroquinolin-3-yl) allylidene-4-methoxyaniline, 3-chloro-3-(2 ,4-dichloroquinolin-3-yl) allylidene-4-methylaniline and 3-chloro-3-(2, 4-dichloroquinolin-3-yl) allylidene-4-chloro aniline at 68, 78 and 64 % yield, respectively. In the final step, 2, 4-dichloro-3, 4'-biquinoline is prepared; several methods were investigated, however, the best yield is 24 % which is obtained under alkaline conditions in the presence of K2CO3 and DMF by microwave irradiation for 10 minutes. The 2, 4-dichloro-7'-methoxy-3, 4'-biquinoline derivative is also prepared in 18 % yield under the same alkaline conditions. The outline of the total synthesis of bisquinoline is presented graphically below. / National Research Fund.

We are surrounded by enormous amounts of ambient mechanical energy that goes to waste such as rain drops, human footfalls, air flow, ocean waves, just to name a few. If such otherwise wasted mechanical energy can be effective converted into electricity, self-powered electronics are very likely to be realized, which can address the limitations of traditional power supplies in many cases, such as wireless sensor networks. Here in this work, two types of energy-harvesting nanogenerators (NGs) based were studied. For piezoelectric nanogenerators, zinc oxide (ZnO) nanowires (NWs) were used as building blocks to develop integrated NGs based on a number of ZnO NWs instead of a single NW. Two types of integrated NGs were developed, which consist of lateral NW arrays and vertical NW arrays. The electric output power was substantially enhanced compared to the design with a single NW. For triboelectric nanogenerators, triboelectric effect was innovatively used as an effective means of harvesting mechanical energy. The operating principle can be explained by the coupling between triboelectric and electrostatic effect. Two types of operating modes were invented, i.e. contact mode and sliding mode. Triggered by commonly available ambient mechanical energy such as footfalls, the maximum output power reached up to 1.2 W. More importantly, self-powered systems were built by using the NG as a power source. It can provide real time power for up to 600 commercial LED bulbs. This research not only provides the fundamentals for NGs but also demonstrates the practicability of using the self-powered technology in our daily life.

This study takes its starting point in the problematic relationship between skills and welfare policies. It poses Sweden’s vocational education and training (VET) as a case which has seen the kind of tripartite efforts that might help us better understand the dynamics underlying a highly developed mixture of social citizenship and efficiency. To better approach this case the study also seeks to combine the theoretical insights provided by the Varieties of Capitalism (VoC) and Power Resources Theory (PRT) schools of thought, capitalizing on an ability to see “both sides of the coin” that such a combination may entail. But to avoid the presumptions that have formed around notions of stable “models” or “worlds”, the study also takes an inductive stance, forming a dialectic strategy that leans heavily on the work of historical institutionalism. Thus a general research question is posed: how can we explain the developments of Sweden's VET as an arena for welfare policies - during the period 1946-1991 - by combining an inductive approach with the insights gained from the theoretical frameworks represented by PRT and VoC? The study proceeds by tracing developments in Sweden’s VET during two sub-periods, taking into account both ideological and business-interest concerns. The aim is first to establish an account of “how” the institutions changed over time. The subsequent analysis brings back the theoretical framework to provide explanations. The study arrives at a number of conclusions: it first of all finds that Sweden’s school-based VET of 1971 itself rested on a firm “cross-class settlement”, which persisted through the reforms of 1991. But when seen as an arena for welfare policies, the foundation appears much weaker: while the reforms of 1971 were influenced by an ambitious welfare policy agenda, the ensuing changes arguably rolled back some of the comprehensiveness and universality previously associated with the labor movement’s education policy. Two underlying hypotheses are presented that focus on the strategic role played by “general skills”: the first hypothesis is that organized capital’s reliance on large firms played an important role in weakening its position vis-a-vis labor, thanks to its dependence on the kind of widely diffused general skills that the labor movement had strategic access to. The second hypothesis is that the same reliance on general skills created difficulties for the Social Democratic Party to create a new cross-class settlement, as circumstances changed. The conclusion suggests further studying the area of general skills as a power resource itself in a comparative perspective.

This research addresses communication reliability in the highly constrained wireless sensor networks environment. We propose a cross-layer, reliable wireless sensor protocol design. The protocol benefits from the body of research in the two areas of wireless sensors reliability research and wireless sensors energy conservation research. The protocol introduces a new energy saving technique that considers reliability as a design parameter and constraint. The protocol also introduces a new back-off algorithm that dynamically adjusts to the data messages reliability needs. Other cross-layer techniques that the protocol introduces are dynamic MAC retry limit and dynamic transmission power setting that is also based on the messages reliability requirements. Cross layer design is defined as the interaction between the different stack layers with the goal of improving performance. It has been used in ad hoc wireless systems to improve throughput, latency, and quality of service (QoS). The improvements gained in performance come at a price. This includes decreased architecture modularity and designs may be hard to debug, maintain or upgrade. Cross-layer design is valuable for wireless sensor networks due to the severe resource constraints. The proposed protocol uses cross-layer design as a performance and energy optimization technique. Nevertheless, the protocol avoids introducing layer interdependencies by preserving the stack architecture and optimizes the overall system energy and reliability performance by information sharing. The information is embedded as flags in the data and control messages that are moving through the stack. Each layer reads these flags and adjusts its performance and handling of the message accordingly. The performance of the proposed protocol is evaluated using simulation modeling. The reference protocol used for evaluation is APTEEN. / We developed simulation programs for the proposed protocol and for APTEEN protocol using the JiST/SWANS simulation tool. The performance evaluation results show that the proposed protocol achieves better energy performance than the reference protocol. Several scalability experiments show that the proposed protocol scales well and has better performance for large networks. Also, exhaustive bandwidth utilization experiments show that for heavily-utilized or congested networks, the proposed protocol has high reliability in delivering messages classified as important. / by Ahmed Badi. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.