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Experimental investigation of geomechanical aspects of hydraulic fracturing unconventional formationsAlabbad, Emad Abbad 10 October 2014 (has links)
Understanding the mechanisms that govern hydraulic fracturing applications in unconventional formations, such as gas-bearing shales, is of increasing interest to the petroleum upstream industry. Among such mechanisms, the geomechanical interactions between hydraulic fractures and pre-existing fractures on one hand, and simultaneous multiple hydraulic fractures on the other hand are seen of high importance. Although the petroleum engineering and related literature contains a number of studies that discusses such topics of hydraulic fracture interactions, there still remain some aspects that require answers, validations, or further supporting data. Particularly, experimental evidence is fairly scarce and keenly needed to solidify the understanding of such complex applications. In this work, the investigation methodology uses a series of hydraulic fracturing laboratory tests performed on synthetic rocks made of gypsum-based cements such as hydrostone and plaster in various experimental set ups. Those laboratory tests aim to closely investigate hydraulic fracture intersection with pre-existing fractures by assessing some factors that govern its outcomes. Specifically, the roles of the pre-existing fracture cementation, aperture, and relative height on the intersection mode are examined. The results show dominant effect of the cement-fill type relative to the host-rock matrix in determining whether hydraulic fracture crossing the pre-existing interface may occur. Similarly, hydraulic fracture height relative to the height of the pre-existing fracture may dictate the intersection results. However, the intersection mode seems to be insensitive of the pre-existing fracture aperture. Moreover, simultaneous multi-fracture propagation is examined and found to be impacted by the interference of the stresses induced from each fracturing source on neighboring fracturing sources. Such stress interference increases as the number of the propagating hydraulic fractures increase. While hydraulic fractures initiating from fracturing sources located in the middle of the fracturing stage seem to have inhibited propagation, outer hydraulic fractures may continue propagating with outward curvatures. Overall, the experimental results and analyses offer more insights for understanding hydraulic fracture complexity in unconventional formations. / text
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Production and properties of epitaxial graphene on the carbon terminated face of hexagonal silicon carbideHu, Yike 15 August 2013 (has links)
Graphene is widely considered to be a promising candidate for a new generation of electronics, but there are many outstanding fundamental issues that need to be addressed before this promise can be realized. This thesis focuses on the production and properties of graphene grown epitaxially on the carbon terminated face (C-face) of hexagonal silicon carbide leading to the construction of a novel graphene transistor structure. C-face epitaxial graphene multilayers are unique due to their rotational stacking that causes the individual layers to be electronically decoupled from each other. Well-formed C-face epitaxial graphene single layers have exceptionally high mobilities (exceeding 10,000 cm ²/Vs), which are significantly greater than those of Si-face graphene monolayers. This thesis investigates the growth and properties of C-face single layer graphene. A field effect transistor based on single layer graphene was fabricated and characterized for the first time. Aluminum oxide or boron nitride was used for the gate dielectric. Additionally, an all graphene/SiC Schottky barrier transistor on the C-face of SiC composed of 2DEG in SiC/Si₂O ₃ interface and multilayer graphene contacts was demonstrated. A multiple growth scheme was adopted to achieve this unique structure.
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Stress analysis of drillstring threaded connectionsSalihu, B. M. January 2011 (has links)
The demand for energy from developed and developing economies of the world is driving the search for energy resources to more challenging environments. The exploration and exploitation of hydrocarbons now requires the drillbit to hit pay zones from drillships or platforms that are located on water surfaces below which is, possibly, in excess of ten thousand feet of water above the sea bed. From Brazil, to the Gulf of Mexico and the Gulf of Guinea on the western coast of Africa, hitherto unfamiliar, but now common, concepts in the drilling parlance such as ultra-deep drilling (UDD), ultraextended- reach drilling (uERD) and slimhole drilling, are employed to reach and produce reservoirs which a few decades ago would seem technologically impossible to produce. This is expected to exert tremendous demands on the physical and mechanical properties of the drillstring components. Limiting factors for reaching and producing oil and gas resources hidden very deep in the subsurface are both the capacity of the drilling rig to support the weight of the drillstring, which in some instances can be several kilometres long, and the bending, tensile and impact stresses the string has to withstand in well trajectories that are getting both longer and more tortuous. Associated with this increased well depths and complex well trajectories is the prohibitive cost penalty of a failed drillstring. The in-service failure of drillstrings has always been an issue in the industry long before the wells become this deep and complex. The global oil and gas industry estimates the cost of string failure to be in excess of quarter of a billion dollars annually. Researchers are continuously looking for ways to design against string failure and improve the level of confidence in drillstrings. Defect-tolerant design, tooljoint geometry modification and surface coldworking are just a few of the ideas that have gained mileage in this effort. Others that are now in consideration are the use of nonconventional materials such as aluminium and titanium alloys for drillstring components. More novel, still, is the use of a combination of two materials - one ‘softer’ than the other to form a hybrid string of two materials of unequal moduli of elasticity. This is done to make the string lighter, reduce stress concentration factor at the connections and place fatigue resistant materials in areas of high well bore curvature.In this work a computational technique in the form of two-dimensional finite element analysis is used to develop a robust model of a drillstring connection and to analyse the stresses on the model of a threaded connection of standard drillstring tooljoint made from alloy steel. Further comparative analyses were undertaken on models of drillstrings made from a newly developed drillstring material for ultra-deep drilling, the UD-165, aluminium and titanium alloys and, finally, on hybrid drillstrings made from two different materials of unequal moduli of elasticity. The aim is not only to develop and validate a better method of computational drillstring analysis but also to use the model to investigate and suggest areas of optimisation that will benefit industry especially in the areas hybrid strings.
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Well Water Quality in Southern Butler County, PennsylvaniaMayes, Scott 18 May 2016 (has links)
The increase in unconventional shale gas extraction in Pennsylvania has resulted in an increased number of groundwater contamination claims. Well water quality was investigated in southern Butler County, PA where 387 unconventional gas wells have been drilled since 2006. A total of 121 households participated in a survey and 238 well water samples were tested. Specific conductivity, pH, and dissolved oxygen in these samples were measured in the field and seven anion concentrations and thirty metal concentrations were measured in the lab. A subset of 91 water wells was also tested for light hydrocarbons (methane, ethane, ethylene, propylene, propane, butane). Pennsylvania DEP file reviews were used to create GIS maps indicating legacy oil and gas, unconventional wells, and plot water testing results. Results indicate few wells had high quality groundwater, with 86% containing one or more contaminants above (secondary) Maximum Contaminant Levels, with manganese (56%), iron (47%), fluoride (18%), TDS (18%), pH (17%), aluminum (17%) the most common. / Bayer School of Natural and Environmental Sciences; / Environmental Science and Management (ESM) / MS; / Thesis;
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The role of cultural understanding and language training in unconventional warfareBeleagaÌ, Constantin Emilian 12 1900 (has links)
Approved for public release; distribution in unlimited. / The level of violence has not only increased constantly over the last decades, but has also shifted in nature from conventional to unconventional. Given these circumstances, Romania's national interests call for the development of unconventional capabilities that are necessary in order to deal with current and future low intensity conflicts. This thesis analyzes the influence of language training and cultural understanding on the overall success of counterinsurgency campaigns. Examining some situations where the U.S. and British forces carried out counterinsurgency operations, this project reveals that ground troops with foreign language skills and cultural training were able to work more efficient with the local population. Cultural awareness facilitated communication and developed interpersonal trust. Additionally, language and cultural training enhanced military personnel's ability to understand the operational environment and to make a more selective use of force. The purpose of this thesis is not to promote a departure from conventional military training, but rather to propose the development of new Romanian military capabilities, the performance of which will increase through a better exploitation of language and cultural resources. / Captain, Romanian Army
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Dopad nekonvenční měnové politiky ECB na střední a východní Evropu: Analýza panelovým VAR modelem / The Impact of Unconventional Monetary Policy of ECB to Central and Eastern European Countries: A Panel VAR AnalysisHálová, Klára January 2015 (has links)
In this thesis we examine the macroeconomic interactions of unconventional monetary policy introduced by European Central bank during crisis by estimating a panel vector autoregression. We study impact of such policies using monthly data from 13 Central and Eastern European countries within seven-year period from 2008 to 2014. We find a positive reactions of output and prices to expansionary unconventional monetary policy shock. Our results provide evidence that decrease in shadow policy rate of ECB leads to rise in output as well as temporary rise in inflation, however, the effect on inflation is weaker and less persistent. We also find that unconventional monetary policy positively influences market uncertainty, but we do not find any significant effect on exchange rates. Individual country estimates suggest that the reaction of exchange rates to non-standard monetary policy shock significantly vary across countries.
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Amatérský překlad titulků k francouzským filmům / Amateur Subtitling of French FilmsHolasová, Kateřina January 2011 (has links)
The aim of the thesis is to describe the problematics of the amateur subtitling. We focus especially on French films subtitling. We concentrate on production, distribution, reception of amateur subtitles and we compare them with the official environment. Further we analyze subtitles of the movie La Haine by one professional and two amateur translators and examine the translation of unconventional French and realii. These days amateur subtitling is a widespread phenomenon. However not many people are familiar with it and understand it. This thesis is supposed to inform about the amateur subtitling environment.
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Immune maturation and lymphocyte characteristics in relation to early gut bacteria exposureBjörkander, Sophia January 2016 (has links)
At birth, the immune system is immature and the gut microbiota influences immune maturation. Staphylococcus aureus (S. aureus) and lactobacilli are part of the neonatal gut microbiota and have seemingly opposite effects on the immune system. S. aureus is a potent immune activator and early-life colonization associates with higher immune responsiveness later in life. Lactobacilli-colonization associates with reduced allergy-risk and lower immune responsiveness. Further, lactobacilli modulate immune-activation and have probiotic features. Here, we investigated S. aureus-induced activation of human lymphocytes, including T regulatory cells (Tregs), conventional T-cells (CD4+ and CD8+), unconventional T-cells (γδ T-cells and MAIT-cells) and NK-cells from children and adults, together with the modulatory effect of lactobacilli on immune-activation. Further, early-life colonization with these bacteria was related to lymphocyte-maturation, plasma cytokine- and chemokine-levels and allergy. S. aureus cell free supernatant (CFS) and staphylococcal enterotoxin (SE) A induced an increased percentage of FOXP3+ Tregs and of CD161+, IL-10+, IFN-γ+ and IL-17A+ Tregs (Paper I). The same pattern was observed in children with a lower degree of activation, possibly due to lower CD161-expression and poor activation of naive T-cells (Paper II). S. aureus-CFS induced IFN-γ-expression, proliferation and cytotoxic capacity in conventional and unconventional T-cells, and NK-cells. SEA, but not SEH, induced activation of unconventional T-cells and NK-cells by unknown mechanism(s) (Paper III, extended data). Lactobacilli-CFS reduced S. aureus-induced lymphocyte activation without the involvement of IL-10, Tregs or monocytes, but possibly involving lactate (Paper III). Early-life colonization with S. aureus associated with increased percentages of CD161+ and IL-10+ Tregs while lactobacilli-colonization negatively correlated with the percentage of IL-10+ Tregs later in life (Paper II). Allergic disease in childhood associated with double allergic heredity, being born wintertime and with higher plasma levels of TH2-, TH17- and TFH-related chemokines early in life. Lactobacilli-colonization associated with lower prevalence of allergy, reduced chemokine-levels and increased levels of IFN-γ in plasma (Paper IV). This thesis provides novel insights into S. aureus- and SE-mediated activation of Tregs, unconventional T-cells and NK-cells and suggests an overall impairment of immune-responsiveness towards this bacterium in children. Further, S. aureus-colonization may influence the maturation of peripheral Tregs. Our data show that lactobacilli potently dampen lymphocyte-activation in vitro and that colonization associates with Treg-responsiveness, altered plasma cytokine- and chemokine-levels and with remaining non-allergic, thereby supporting the idea of lactobacilli as important immune-modulators. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p><p> </p>
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Levantamento etnobotânico das plantas alimentícias nos municípios de Areias e São José do Barreiro - SP: um patrimônio nos quintais urbanos / Ethnobotanic survey of the food plants in the cities of Areias and São José do Barreiro - SP: a heritage in urban homegardens.Ranieri, Guilherme Reis 09 May 2018 (has links)
Nas cidades de São José do Barreiro e Areias, no Vale do Paraíba Paulista é possível encontrar dentro do centro urbano características associadas à ruralidade, como o cultivo de hortaliças e frutas nos quintais, além da presença de detentores de um conhecimento botânico sobre plantas alimentícias. Os quintais, as plantas e os saberes são considerados patrimônio, apresentando a contextualização para a construção de uma definição integradora, tendo em vista os saberes etnobotânicos e suas peculiaridades dentro da população estudada. Dessa forma, o presente trabalho teve como objetivo caracterizar o uso de dessas plantas alimentícias nesses quintais, com vistas a identificar as vulnerabilidades nas quais plantas e os saberes a elas associados estão sujeitos. Foram entrevistados 67 residentes dos dois municípios, e encontradas 172 espécies e variedades alimentícias, das quais 31 são consideradas espontâneas. Nos quintais, foram listadas ainda 20 espécies que possuem potencial na alimentação, mas não foram citadas. O conhecimento de plantas alimentícias da população é notável, contudo, diversos processos podem comprometer a transmissão desses saberes. Esses patrimônios estão sujeitos ao desaparecimento, de forma que os saberes botânicos detidos por parte da população também estão em risco. / In the cities of São José do Barreiro and Areias, in the Vale do Paraíba Paulista, it is possible to find in the urban center, characteristics associated with rurality, such as the cultivation of vegetables and fruits in the homegardens, besides the presence of holders of a botanical knowledge about edible plants. The homegardens, the plants and the knowledge are considered heritage, presenting the contextualization for the construction of an integrative definition, in the perspective of ethnobotanical knowledge and its peculiarities in that population. Thus, the present work aimed to characterize the use of these food plants in these homegardens, in order to identify the vulnerabilities in which plants and the associated knowledge are associated. We interviewed 67 residents in the two municipalities, and are found 172 edible species and varieties of plants, of which 31 are considered spontaneous. In the homegardens, 20 species have potential for humans consumption, but were not mentioned. The knowledge of food plants in the population is remarkable, however, several processes can compromise the transmission of these knowledge. These heritage is subject to disappearance, so that the botanical knowledge held by the population is also at risk.
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Aspectos regulatórios e institucionais do desenvolvimento de gás não convencional: uma análise comparativa entre Brasil e Estados Unidos / Regulatory and institutional aspects of unconventional gas development: a comparative analysis between Brazil and the United States of AmericaAraújo, Renata Rodrigues de 29 July 2016 (has links)
Esta tese avaliou se o Brasil, sob a perspectiva regulatória, encontra-se preparado para iniciar localmente o desenvolvimento de gás de folhelho, principal fonte de gás não convencional. Para tal, adotou como metodologia uma análise comparativa entre a legislação do setor de gás natural dos EUA e do Brasil, com foco na regulamentação das operações de fraturamento hidráulico, buscando evidenciar e contextualizar os principais fatores de sucesso da experiência estadunidense. Na realização dessas investigações foram utilizados diversos conceitos da Política Ambiental que podem ser empregados na elaboração de normas e condutas voltadas para o gás não convencional. Pautada no resultado dessas análises, que apontou a necessidade de estudos ambientais, sociais e econômicos mais aprofundados, apresentou-se como principal recomendação uma proposta de Avaliação Ambiental Estratégica (AAE). Tal ferramenta pode orientar a decisão do governo em relação à exploração de hidrocarbonetos não convencionais no Brasil, bem como auxiliar o país na obtenção de uma licença social para operar e na criação das condições necessárias para explorar seus possíveis recursos de gás de folhelho de maneira segura e responsável. / This thesis assesses whether Brazil, from the regulatory point of view, is ready to start a local production of shale gas, the main source of unconventional gas. For this purpose, the study conducted a comparative analysis of the primary laws regulating of oil and gas exploration and production activities in the USA and Brazil, focusing on the hydraulic fracturing operations, in order to determine and contextualize the major factors of success for the American shale gas experience. Several approaches of Environmental Policy that can be used in the development of standards and rules for unconventional gas were used. The results indicated the need for additional environmental, social and economic studies. Therefore, a Strategic Environmental Assessment (SEA) proposal was the main recommendation. This tool may guide the government\'s decision about the unconventional resources production in Brazil, help the county to achieve a social license to operate and meet the conditions required to explore its potential shale gas resources.
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