The aim of this thesis is to reconsider energy extraction from black hole magnetospheres, and more specifically the Blandford-Znajek (BZ) process from an effective field theory (EFT) perspective. Superradiant instabilities of scalar and vector bound states in the presence of a rotating black hole will be reviewed when the inverse mass of the black hole is much smaller than the Compton wavelength of the bound state particle. Two different matching calculations will be described for the vector bound state case and the overall decay rate will be compared. Force-free electrodynamics will be motivated and discussed in the context of the BZ process. Using a perturbation expansion, the Blandford-Znajek process will be reviewed up to second order in the rotation parameter. The absolute-space/universal-time (3+1) viewpoint will be discussed and applied to the BZ process and an EFT-like description will be discussed when the black hole horizon is parametrically small. Using differential forms, a simplified framework for the BZ process will be introduced in the (3+1) formalism and the field strength F will be simplified in the slow-rotation limit up to first-order in the rotation parameter. Finally, the Blandford-Znajek process will be considered as a superradiant process in the massive vector limit and the total energy flux in this (new) regime will be compared to the known BZ energy flux. / Graduate

This dissertation explores the concept of Actually Existing Democracy in the transnational public sphere through the experiences of the Coalfields Delegation to the United Nations Commission for Sustainable Development (UNCSD). In particular, this research examines the differential impacts of energy extraction on local communities, and what the term justice might usefully mean in the context of transnational energy politics. I provide an account of justice that engages with the theories of Nancy Fraser and Pierre Bourdieu and mines their insights to provide a novel intervention in debates about justice and the public sphere. I start by defining justice as a transnational construct using theories of the nation-state and then discuss the nature and roles of counterpublics, specifically the Coalfields Delegation, in transnational justice. I then explore Fraser's constructs of redistribution, recognition, and representation, viewing each through Bourdieu's theories of habitus and field. I show that the process through which counterpublics seek justice is mediated through the operations of power in the economic, cultural, and political fields (adopting Fraser's definition of culture over Bourdieu's). To achieve justice, it is insufficient to suggest that movement in a field proceeds directionally; rather, Fraser and Bourdieu are in accord in suggesting that these fields need to be deconstructed (Fraser's term) by counterpublics adopting heterodox practices to challenge the established ordering of the field. Energy injustice, in the particular form of mountaintop removal coal mining, occurs locally, yet is inherently global in its implications through the processes of international trade and consumption. Therefore, the appropriate level at which to examine these seemingly "local" concerns is that of the transnational. In the case of the Coalfields Delegation, appeals have been made at the local, state, and national levels, to no avail. The group pursued several interlinked strategies at the UN. To the extent that their plight is one of economic disparity, the Coalfields Delegation has sought to redefine economic power in a manner different from global capitalism. Where cultural marginalization has been used as a basis for justifying disparate impacts on mining communities, the Delegation decidedly used its own formulation of "culture" as a strategic publicity mechanism. In pursuing representation at the UNCSD, the Delegation began defining its concerns in global terms, suggesting human rights violations, and placing coal mining within the context of global sustainability and climate change. However, in so doing, members of the Delegation started to reconceive themselves in solidarity with other similarly affected groups represented at the UNCSD. Their quest for global redress has not been one of straightforward acts of agency, but rather should be viewed as an oscillation between agency and structure. Fields exert counter-pressure, however, as the Delegation members grew in experience and sophistication, their habitus changed accordingly. My research explores the dynamic play of these social forces by linking the ideas of public sphere and field, counterpublic and habitus, to develop a new way in which researchers might both describe and trace advocacy group efforts to secure justice in the transnational public sphere. / Ph. D.

Oscillating Water Column (OWC) device is a relatively practical and convenient way that converts wave energy to a utilizable form, which is usually electricity. The OWC is kept inside a fixed truncated vertical cylinder, which is a hollow structure with one submerged open end in the water and with an air turbine at the top. The research adopts potential theory and Galerkin methods to solve the motion of the OWC. Based on the air-water interaction model, optimal OWC design for energy extraction from regular wave is explored. The hydrodynamic coefficients in scattering and radiation potential are solved using Galerkin approximation. The numerical results for the free surface elevation have been verified by a series of experiments conducted in the University of New Orleans Towing Tank. The effect of geometric parameters on the response amplitude operator (RAO) of OWC is studied and amendment of the equation for evaluating the natural frequency of the OWC is made. Using the model of air-water interaction under certain wave parameters and OWC geometric parameters, a computer program OWC Solution is developed to optimize the energy output from the system. Optimization results by the program OWC Solution lead to an effective method to design the OWC system.

One of the most pressing and polarizing issues in Western Canada today, and for many First Nations groups in particular, is the oil sands of Alberta. My thesis is entitled Energy Uncertainty: The Effects of Oil on the Woodland Cree First Nation. My research is focused on understanding how long-term energy extraction affects the past, present, and futures of the members the Woodland Cree First Nation (WCFN) who are demanding an active role in the planning and consultation processes that affect their lives and their traditional lands. I have found that the energy consultation process is not working for the interests of the WCFN and the effects of oil extraction in this community are examples of how and why it is not working. During the summer of 2013 I spent nine weeks in the WCFN community and used three methods of research: participant observation, interviews, and literature analysis. I completed 22 interviews during my field work research, and made use of nine transcribed interviews with WCFN elders collected in 1995 by Rhonda Laboucan. I used a grounded approach to the content and thematic analysis of my interview and field note data. My thesis is guided by a political ecological approach because this framework challenged me to look at this subject from many angles and perspectives. This approach has kept my research from being narrowly focused on abstracted or stereotypical aspects of the energy extraction process which I cannot understand without attention to its social, political, environmental, and spatial aspects. The body of my thesis includes three chapters which explore: • The practical realities of energy consultation and its relation to Treaty Eight and Traditional Knowledge. • The complex relationship between temporality, fatalism, and the effects of the oil industry on the people, land, and animals of the WCFN. • A detailed ethnographic description of the events and processes that followed a contaminated water spill on the WCFN traditional land. My key findings include: consultation is not working for the interests of the WCFN; oil is impacting the animals, environment, and WCFN community; oil-related spills are affecting (but not being dealt with in a way that respects) WCFN people or land; and there are problems with collection, interpretation, dissemination, and even access to energy extraction and consultation information. My research helps to fill the gaps in our understanding of the complex effects of long-term energy extraction on small communities, in particular the impacts of oil and oil sands development in a small First Nations community context.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See item for full text / AFRIKAANSE OPSOMMING: Sien item vir volteks

Thesis (D. Tech. Electrical engineering) --Vaal University of Technology / A comprehensive study upon "Non-conventional methods for energy extraction from the high voltage transmission lines" was addressed in this thesis. As defined in this study, a non-conventional method to extract energy is one that does not touch the conductors of the line. The theoretical framework which originated in the Maxwell's equations was presented as a base for discussion of all the methods and the conditions for the extraction to be possible. This study presents various methods such as capacitive and inductive to extract energy from high voltage alternating current transmission lines (HVAC). Although in theory, for high voltage direct current transmission lines (HVDC), the conditions for extraction are not matched, there remain some methods that could still attract interest. The centre point of this thesis is the new power application of the Rogowski coil. This method is analysed in full extent starting from theoretical modelling, computer simulations, design of the actual Rogowski coil and power electronics associated with it, and experimental results on a reduced scale model. In doing this, strong mathematical tools and computer software such as Matlab 6, Quick Field and MathCAD were used. At the end of this thesis, some conclusions are presented together with new ideas for further research in the field.

Image descriptors play an important role in image representation and analysis. Multi-resolution image descriptors can effectively characterize complex images and extract their hidden information. Wavelets descriptors have been widely used in multi-resolution image analysis. However, making the wavelets transform shift and rotation invariant produces redundancy and requires complex matching processes. As to other multi-resolution descriptors, they usually depend on other theories or information, such as filtering function, prior-domain knowledge, etc.; that not only increases the computation complexity, but also generates errors. We propose a novel multi-resolution scheme that is capable of transforming any kind of image descriptor into its multi-resolution structure with high computation accuracy and efficiency. Our multi-resolution scheme is based on sub-sampling an image into an odd-even image tree. Through applying image descriptors to the odd-even image tree, we get the relative multi-resolution image descriptors. Multi-resolution analysis is based on downsampling expansion with maximum energy extraction followed by upsampling reconstruction. Since the maximum energy usually retained in the lowest frequency coefficients; we do maximum energy extraction through keeping the lowest coefficients from each resolution level. Our multi-resolution scheme can analyze images recursively and effectively without introducing artifacts or changes to the original images, produce multi-resolution representations, obtain higher resolution images only using information from lower resolutions, compress data, filter noise, extract effective image features and be implemented in parallel processing.

Image descriptors play an important role in image representation and analysis. Multi-resolution image descriptors can effectively characterize complex images and extract their hidden information. Wavelet descriptors have been widely used in multi-resolution image analysis. However, making the wavelet transform shift and rotation invariant produces redundancy and requires complex matching processes. As to other multi-resolution descriptors, they usually depend on other methods, such as filtering function, prior-domain knowledge, etc.; that not only increases the computation complexity, but also generates errors. We propose a novel multi-resolution scheme that is capable of transforming any kind of image descriptor into its multi-resolution structure with high computation accuracy and efficiency. Our multi-resolution scheme is based on sub-sampling each image into an odd-even image tree. Through applying image descriptors to the odd-even image tree, we get the relative multi-resolution image descriptors. Multi-resolution analysis is based on downsampling expansion with maximum energy extraction followed by upsampling reconstruction. Since the maximum energy usually retained in the lowest frequency coefficients; we do maximum energy extraction through keeping the lowest coefficients from each resolution level. Our multi-resolution scheme can analyze images recursively and effectively without introducing artifacts or changes to the original images, produce multi-resolution representations, obtain higher resolution images only using information from lower resolutions, compress data, filter noise, extract effective image features and be implemented in parallel processing.

In the research part is a basic overview of vapor thermodynamics is processed. It deals with the historical development of gas liquefaction systems, divided according to the authors of the proposals. It includes basic knowledge of thermodynamics of gas liquefaction. In the field of liquefied gas storage, it contains a brief overview of the division of storage vessels and insulation materials. It also deals with the extract of energy from liquid air. It contains an adiabatic design of electrical energy storage using air liquefaction (LAES). The conclusion describes the proposed design, economic analysis and perspectives of using LAES.

As machine topologies and technologies mature, the fundamental function of the device is honed. Direct drive machines have the potential to launch the renewable energy sector into a new era of large scale, reliable, offshore power generation. With advancements in new technologies, such as superconductivity, the reduction of generator mass due to incorporation of machine and device structures, the continued advancements in component and system reliability; direct drive generators have the ability to outsize geared wind systems and simplify submerged linear and rotary power generation. The research held within this thesis will focus on improving direct drive power take off systems for offshore renewable energy power generation by splitting the area into four parts. The first part will discuss the various methods of energy extraction within the offshore and marine environment. The future of the sector will be discussed, and a forecast of technological advancement and existing reliability issues will be provided based on current data. The second part will focus on drive trains and direct drive generators, assessing the current topologies and suggesting alternatives that may thrive in a variety of large and small offshore renewable machines. The third part investigates the application of novel linear bearings in direct drive systems for offshore and submerged operation. A brief study of the loads found in wave applications will be presented and the testing of several polymer bearing materials will be outlined. The final part will discuss the potential benefits of flooding the airgap of a direct drive generator with sea water for marine applications. Results will be presented from two linear test rigs and the marinisation of devices will conclude the report.