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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Bahamian Quaternary Geology and the Global Carbon Budget

Larson, Erik Bond 17 May 2014 (has links)
Sea-level change during the Quaternary has had significant impacts on the geology of the Bahamas and the global carbon budget. During periods of low sea-level position conduit caves form in the Bahamas as a function of their respective water budgets. These conduit caves can then collapse and if this collapse reaches the surface a progradational collapse blue hole can be made. Upon subsequent sea-level rise these blue holes can become sediment inilled. Tidal pumping through these sedimentilled blue holes can result in the formation of whitings. Whitings are formed when the tidally pushed water warms and degasses CO2, driving the precipitation of CaCO3. Whitings are also formed on the shallow banks by resuspension by fish. As sea-level fluctuates the amount of land in the Bahamas and other carbonate regions increases or decreases with sea-level fall or rise, respectively. As the amount of land increases in the Bahamas and other carbonate regions, there is a decrease of carbonate rock exposure at high latitudes due to glaciation. The loss of high latitude carbonates is made up for in the gain of low latitude carbonates in terms of rates of inorganic carbon drawdown associated with karst processes. Additionally, this inorganic carbon draw down from karst processes represents approximately 16% of the unknown carbon sink as reported by the IPCC. This study is significant in that it contributes to the understanding of sea-level fluctuations in relation to the geology of the Bahamas and the global carbon budget.
172

Study Of Discharge Coefficient And Trends In Film Cooling Effectiveness Of Conical Holes With Increasing Diffusion Angles

Zuniga,, Humberto 01 January 2006 (has links)
Previous studies indicate that increasing the diffusion angle in conical film-cooling holes leads to an improvement in their film cooling effectiveness. Discharge coefficient and film cooling effectiveness measurements are conducted to characterize this behavior. Part of the focus of this investigation is to find out how this trend develops and attempt to ascertain the optimum cone angle, if possible. Six test plates, each with one row of eight conical-shaped cooling holes of equal diffusion angles of 0, 1, 2, 3, 6, or 8 [degrees], with respect to the hole axis are used in this study. The ratios of the hole exit areas to the inlet areas range from 1 to 2.85. Coolant injection angle for all holes is at 35 degrees to the horizontal, in the direction of the main flow. Coefficients of discharge of all holes are reported under flow conditions. Temperature sensitive paint, TSP, is the technique used to find the temperature distribution downstream of the cooling holes and determine the laterally averaged film-cooling effectiveness. Data are obtained for blowing ratios ranging from 0.5 to 1.5, at a constant density ratio of 1.26. Results and trends are compared with established literature, which also recommends that a cylindrical entry length for diffused holes should be at least 4 diameters long. The effect that an added entry length has on the 3-degree conical plate's cooling effectiveness is also explored. Data are compared to baseline cylindrical holes, as well as to fan-shaped film holes found in open literature. Results indicate that the conical holes with larger diffusion angles provide strikingly even film protection and outperform fan shaped and cylindrical holes under certain conditions over extended downstream distances. Also, the addition of a cylindrical entry length to a conical hole, by providing a manageable metering diameter, should ease their usage while providing the full benefits of the conical geometry which may one day lead to numerous industrial applications.
173

Newtonian vs. MOND Gravity: Dwarf Spheroidal Galaxies With Central Massive Black Holes

Hogsett, Elijah Glen 18 July 2023 (has links)
No description available.
174

ANALYSIS OF BELL HOLE MORPHOLOGY AND DISTRIBUTION: A TOOL FOR EVALUATING FORMATIONAL PROCESSES

Dogwiler, Toby Joseph 07 August 1998 (has links)
Bell holes are described as vertical, cylindrical, dissolutional cave ceiling voids. Quantitative analysis of bell holes in San Salvador, Bahamas; Isla de Mona, Puerto Rico; Kentucky; and New York permit bell hole morphology to be contrasted in various geological settings and speleogenetic regimes. Mean bell hole height is 36 cm with a width of 34 cm and cross-sectional area of776 cm 2. Bell holes have elliptical openings, conical to cylindrical profiles, strong vertical development, and sometimes are associated with bell pits. Bell hole width remains constant between the study localities, but height varies. Several processes have been proposed to explain bell hole development: bat activity, condensation corrosion, phreatic degassing, vadose percolation, and phreatic convection cells. The vadose mechanisms seem unreasonable in light of bell hole morphology and setting. Thus, a phreatic process functioning in a laminar or slow-moving turbulent flow regime most likely accounts for bell hole formation.
175

Reverberation Mapping of the Continuum Source in Active Galactic Nuclei

Fausnaugh, Michael Martin 23 October 2017 (has links)
No description available.
176

Optimizing exploratory drilling locations

Chou, Da-rong January 1982 (has links)
No description available.
177

Global networks and the reorganization of production in the clothing industry of post-socialist Ukraine

Kalantaridis, Christos, Slava, S., Vassilev, I. January 2008 (has links)
No / In this article we examine how processes of globalization and the nature of emerging inter-firm relationships influence the organization of production in a post-socialist region, using the case of the clothing industry in Transcarpathia, Western Ukraine. We combine insights from two perspectives, the global commodity chain approach and the new regionalism. The focus on both institutional setting and interfirm relationships is essential in regions undergoing rapid change. In the article we also use Burt's concept of structural holes and the idea of a competence-difficulty gap to examine the nature of relationships within networks of firms, arguing that global integration can be viewed as a bridging process. The evidence comes from surveys and fieldwork conducted between 1997 and 2004, providing a longitudinal analysis of the same firms. Among other findings, we show that the difficulty of doing business locally may make relationships more stable. With respect to industrial structure, international subcontracting and joint-venture arrangements enable technological modernization in assembly and parts of preassembly, but also result in the demise of high-value added competences.
178

Radiative characteristics of spherical cavities having partially or completely specular walls

Kowsary, Farshad January 1989 (has links)
The radiant exchange problem for an isothermal spherical cavity having diffuse-specular walls is solved and the distribution of the local heat transfer for various opening angles and surface emissivities is obtained. Subsequently, the overall emission from the cavity (i. e., the apparent emissivity of the cavity) is calculated for various opening angles and surface conditions. In addition, the overall absorption characteristics of spherical cavities having purely specular walls is investigated analytically for the case of collimated radiation entering the cavity. Various opening angles and surface conditions are considered. The Monte Carlo method is utilized to support the results obtained from the analytical calculations. Results show that in spherical cavities the apparent emissivity is not very sensitive to the degree of specularity of the cavity wall. Also, there are situations in which the diffuse cavity is a more efficient emitter than a specular cavity. Absorption characteristic results show that for cavities having purely specular walls the absorption of collimated radiation is highly dependent on the angle of incidence of radiation on the opening for small opening angles. / Ph. D.
179

Women of Needles and Holes

Munoz, Michelle 01 January 2024 (has links) (PDF)
Women of Needles and Holes is a hybrid memoir focusing on the immigrant story of the speaker's lineage through the lens of mother-daughter relationships. Through a collection of lyrical essays, prose poems, journal entries, and poems, the narrative explores the concept of curing or succumbing to generational curses. There is an emphasis on the importance of female relationships and the complicated nature of motherhood. The speaker's maternal line is explored by framing the grandmother's and mother's stories through needle and sewing motifs. The family's Cuban and Spanish heritage is considered through the perception of each woman's relationship with both countries. The speaker's matriarchal history binds together when shifts in point-of-view occur such as in "A Cuban Cockroach," "The Burning Street," and excerpts from the speaker's mother's journal. Women of Needles and Holes explores what it means to pass down customs, female roles, traumas, and fears.
180

Investigation of the Cause of Drill Cuttings in Horizontal Holes : A case of Kankberg and Garpenberg mines, Boliden

Sampa, Ng'andu January 2024 (has links)
The implementation of nitrate-free emulsions in Boliden's blasting operations prompted an in-depth investigation into the accumulation of drill cuttings following drilling activities. This master's thesis aimed to understand the contributing factors and quantify drill cuttings, particularly in view of the planned introduction of a new explosive compound. The focal points of the study were the Boliden Kankberg and Garpenberg mines, where a rich variety of data sources were harnessed. The research encompassed a thorough literature review highlighting enduring challenges in drilling and factors that influenced cuttings transport. The study delved into the complex relationships between drilling parameters, including drilling angle, rate of penetration, lithology, and other variables, examining their role in drill cuttings generation and hole evenness. This thesis was a response to the planned introduction of nitrate-free emulsions in Boliden's blasting operations, catalyzed by concerning observations at the Kankberg mine. These observations revealed a significant presence of residual drill cuttings, which raised concerns about their potential impact on blasting effectiveness. The primary focus was on the Kankberg and Garpenberg mines, allowing for a comprehensive exploration of data mainly obtained by filming the drill holes after drilling. A noteworthy aspect of the study was the development and application of a MATLAB-based image processing code to estimate the volume of residual drill cuttings in drill holes. This quantitative approach served as a robust foundation for the investigation. One key finding of the investigation was the disparity in drill cuttings accumulation between the investigated holes in Garpenberg and Kankberg. The "Working from Backwards" approach, employed at the Kankberg mine, underscored the critical importance of controlled drilling angle and rate of penetration in mitigating drill cuttings and achieving uniform drilling outcomes. While this research shed light on these factors, further exploration was needed to fully grasp their intricacies and identify additional variables influencing drill cuttings and hole evenness. These findings offered vital guidance for the development of strategies and practices to enhance drilling operations in the future. Additionally, cluster analysis results emphasized the pivotal role of lithological characteristics in drill cuttings generation. The study provided practical recommendations, including the identification of lithological variations through enhanced mapping, the adjustment of drilling parameters, and the optimization of drilling methods tailored to specific lithologies. / <p>Successful</p>

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