Thesis (M.S. in architecture)--Washington State University, December 2005. / Includes bibliographical references (p. 102-106).

Thesis (M.S. in Applied Physics and M.S. in Electrical Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Gamani Karunasiri, James Luscombe, Robert Hutchins, John Powers. Includes bibliographical references (p. 129-131). Also available online.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 46 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 42-43).

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 195-210).

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains x, 65 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 58-60).

In a semiconductor, negative charge is carried by conduction-band electrons and positive charge is carried by valence-band holes. While charge transport properties can be understood by considering the motion of these carriers individually, the optical properties are largely determined by their mutual interaction. The hydrogen-like bound state of an electron with a hole, or exciton, is the fundamental optical excitation in direct-gap materials such as gallium arsenide and cadmium telluride. In this dissertation, we consider charged excitons, or trions. A bound state of an exciton with a resident electron or hole, trions are a relatively pure manifestation of the three-body problem which can be studied experimentally. This is a subject of practical as well as academic interest: Since the trion is the elementary optical excitation of a resident free carrier, the related optical processes can open pathways for manipulating carrier spin and carrier transport. We present three experimental investigations of trion-based optical processes in semiconductor quantum wells. In the first, we demonstrate electromagnetically induced transparency via the electron spin coherence made possible by the trion transition. We explore the practical limits of this technique in high magnetic fields. In the second, we present a direct measurement of trion and exciton oscillator strength at high magnetic fields. These data reveal insights about the structure of the trion's three-body wavefunction relative to that of its next excited state, the triplet trion. In the last, we investigate the mechanism underlying exciton-correlated tunneling, an optically-controllable transport process in mixed-type quantum wells. Extensive experimental studies indicate that it is due to a local, indirect interaction between an exciton and a hole, forming one more example of a trion-mediated optical process. This dissertation includes previously published co-authored material.

Orientador: Denis José Schiozer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-23T18:49:30Z (GMT). No. of bitstreams: 1 Teixeira_GuilhermeNascimentoRodrigues_M.pdf: 5330624 bytes, checksum: 05bfb1e1e9cd9bb8c8c69e3e8ddc0eac (MD5) Previous issue date: 2013 / Resumo: O processamento submarino é considerado uma tecnologia potencial para antecipar a produção de campos localizados em águas profundas e reduzir, em alguns casos, os custos associados às instalações de superfície. Ele pode ser definido como qualquer tratamento dado ao fluido produzido no leito submarino. Dentre as tecnologias disponíveis, a Separação Submarina Gás- Líquido (SSGL) atualmente é a mais avançada para aplicações em águas profundas. A maneira mais recomendada para quantificar as vantagens de longo prazo dessas tecnologias é através da Modelagem Integrada da Produção (MIP), uma abordagem que integra a simulação de reservatórios com o sistema de produção do campo. A motivação do presente trabalho surgiu da necessidade de quantificar o incremento de produção de óleo a ser obtido pelas tecnologias de processamento submarino. O objetivo é utilizar a MIP para comparar a produção de um reservatório através de duas tecnologias de elevação artificial: SSGL e Gas Lift Contínuo (GLC). A comparação entre o SSGL e o GLC foi realizada em dois estudos de casos. No primeiro, utilizou-se um modelo homogêneo para que a comparação se restringisse apenas aos métodos de elevação. No segundo caso, um modelo sintético heterogêneo, construído a partir de dados reais, foi utilizado para comparar os métodos numa situação próxima à real. Os resultados mostraram a capacidade da tecnologia SSGL em antecipar a produção de óleo, através da redução da contrapressão e pelo aumento da queda de pressão no poço, conhecida como drawdown. Além disso, a manutenção da pressão do reservatório se mostrou um elemento chave para a tecnologia SSGL. A combinação das tecnologias (SSGL + GLC) mostrou ser uma boa opção para incrementar a produção de óleo durante um período de revitalização do campo. O SSGL foi capaz de produzir o mesmo volume de óleo que o GLC utilizando um diâmetro de coluna e linha de produção menor. Por fim, a MIP mostrou ser flexível para permitir simular casos com restrições tecnológicas, difíceis de serem consideradas apenas com a simulação de reservatórios / Abstract: Subsea processing is considered a potential technology to increase production in deepwater fields and reduce, in some cases, costs related to surface facilities. It can be defined as any treatment of the produced fluids performed on the seabed. Among the available technologies, Subsea Gas- Liquid Separation (SGLS) is the most advanced for deep water applications. The most recommended way to quantify the long term advantages of this technology is through Integrated Production Modeling (IPM), which integrates reservoir and surface facilities models into a single model. The motivation of the present work is the need to quantify the incremental oil recovery that might be achieved through subsea processing. The objective is to compare the production of a reservoir through two artificial lift methods: SGLS and Continuous Gas Lift (CGL). The comparison between SGLS and CGL was performed in two case studies. In the first one, a homogeneous reservoir model was used, so the comparison was focused on the artificial lift technologies. In the second case, a heterogeneous reservoir model, built with real data, was used to compare both methods in a more realistic reservoir scenario. The results showed the capability of anticipating production by the reduction of the backpressure and the increase of the drawdown through SGLS. Besides, reservoir pressure maintenance appeared as key element for this technology. A combination of the technologies (SGLS + CGL) was found to be a good option to increase oil production during the revitalization phase of the field. SGLS was able to produce the same volume of oil obtained with CGL using a smaller tubing and production diameter. IPM showed a more flexible option to simulate scenarios with technological constraints, capturing effects that are difficult to be caught using only reservoir simulation / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

Millions of Canadians rely on private groundwater wells to access drinking water, which presents many challenges including a lack of government regulations, and limited resources for maintenance, monitoring, management, and protection. These challenges result in an increased risk of acute gastrointestinal illness in private well users. The goal of this work is to improve the understanding of drivers of E. coli fate and transport in groundwater using a data-driven approach to better inform well owners and policy makers. Specifically, the objectives include: exploratory analysis of the physical and human drivers of private well contamination; advancing the understanding of the relationships between land use-land cover and E. coli presence in wells; assessment of rainfall intermittency patterns as a driver of contamination, as an alternative to standard lag times; and, the development of data-driven explanatory models for E. coli contamination in private wells that move towards a novel coupled-systems approach. This research utilizes a large dataset with 795,023 contamination observations, 253,136 unique wells, and over 33 variables (i.e., microbiological, hydrogeological, well characteristic, meteorological, geographical, and testing behaviour) across Ontario, Canada between 2010 and 2017. Data used includes the Well Water Information Database, Well Water Information System, Daymet, Provincial Digital Elevation Model, Ontario Land Cover Compilation, Southern Ontario Land Resource Information System, and Roads Network. Data analysis methods range from univariate and bivariate analyses to supervised and unsupervised machine learning techniques, including regression, clustering, and classification. This work has contributed important understandings of the relationships between E. coli contamination and well and aquifer characteristics, seasonality, weather, and human behaviour. Specifically, increased well depth reduced, but did not eliminate, likelihood of contamination; wells completed in consolidated material increased likelihood of contamination; the most significant driver of contamination was identified as land use - land cover, which was categorized into four classes of E. coli contamination potential for wells, ranging from very high to low; latitude was found to drive seasonality and consequent weather patterns, leading to the creation of geographically-based seasonal models; liquid water (i.e., rainfall, snow melt) was a key driver of contamination, where increased water generally increased presence of E.coli while causing decreasing prevalence; time of year, not habit, drove user testing, generally peaking in July; and, a surrogate measure of well user stewardship was identified as driving time to closest drop-off location. Further, this work has contributed methodological advancements in identifying drivers of groundwater contamination including: utilizing literature confidence ratings alongside regression analyses to supply strategic direction to policy makers; demonstrating the value of large datasets in combination with innovative machine learning techniques, and subject matter expertise, to identify improved physically-based understandings of the system; and, highlighting the need for coupled-systems approaches as physical models alone do not capture human behaviour-based factors of contamination. / Thesis / Doctor of Engineering (DEng) / There are millions of people globally relying on private groundwater to access drinking water. Unfortunately, these wells come with many challenges including a lack of government regulations, and limited resources for maintenance, management, and protection. These challenges also result in an increased risk of illness in private well users. Groundwater research is often limited by lack of numerical data, making it extremely difficult to understand how groundwater and contaminants are transported. This research utilizes a large dataset with 795,023 contamination observations, 253,136 unique wells, and over 33 variables (i.e., well and aquifer characteristics, human behaviours, weather-related) across Ontario, Canada between 2010 and 2017. The work in this thesis utilizes a data-driven approach, using various machine learning techniques combined with subject matter expertise, to uncover trends and insights into when and how contamination events occur in private wells, to inform policy makers and empower well users.

No / The current work’s main aims are to discuss and introduce the main aspects of geothermal wells and reservoirs, including well systems, heating, drilling, and completion. There are several systems and methods for extracting heat energy from underground formations, such as open/closed-looped, vertical/horizontal, pond, and slinky mechanisms, which require different distribution and efficient energy transfer systems. The geothermal well completion method and cementing process are similar to hydrocarbon wells. However, the materials and cement used in geothermal wells must be compatible with hot water and high-pressure-high-temperature (HPHT) steam. Therefore, careful planning for compatible drilling-completion operations with geothermal reservoirs is essential.

An insulated coaxial pipe for a 50,000 ft drilled geothermal well was designed, in order to remove heat from the earth's crust by the circulation of water through a single well. The design took into consideration means of insulating and supporting the inner pipe, thermal expansion, the large hydrostatic pressures involved, and a feasible means of installing the ten mile pipe. A thermodynamic analysis of the aboveground power generation system, including a once-through steam generator, condenser, circulating pumps, and a feed-water heater system, was made in order to obtain the maximum thermal efficiency. The drilled geothermal power generation equipment is different from that of conventional fossil or nuclear-fired equipment in that the water temperature arriving at the wellhead is continuously varying due to the removal of heat from the earth's crust. Due to the fact that the earth is a poor conductor of heat, continuous operation of the well results in the water at the wellhead falling below an acceptable power generation temperature after a relatively short time period. Therefore, intermittent operation of several wells in staggered fashion using the same aboveground power generation equipment is required. A determination of the well operating characteristics including optimum mass flow and well cut-on and cut-off temperatures was made. From this a justifiable well cost was determined in order to provide geothermal electrical power and process heat at a reasonable cost. / Master of Science