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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.
41

Instructional decision making of high school science teachers

Carver, Jeffrey S. Rhodes, Dent. Hunter, William J. F. January 2006 (has links)
Thesis (Ed. D.)--Illinois State University, 2006. / Title from title page screen, viewed on April 22, 2007. Dissertation Committee: Dent M. Rhodes, William J.F. Hunter (co-chairs), Thomas P. Crumpler. Includes bibliographical references (leaves 251-256) and abstract. Also available in print.
42

Investigation on the effects of ultra-high pressure and temperature on the rheological properties of oil-based drilling fluids

Ibeh, Chijioke Stanley 15 May 2009 (has links)
Designing a fit-for-purpose drilling fluid for high-pressure, high-temperature (HP/HT) operations is one of the greatest technological challenges facing the oil and gas industry today. Typically, a drilling fluid is subjected to increasing temperature and pressure with depth. While higher temperature decreases the drilling fluid’s viscosity due to thermal expansion, increased pressure increases its viscosity by compression. Under these extreme conditions, well control issues become more complicated and can easily be masked by methane and hydrogen sulfide solubility in oil-base fluids frequently used in HP/HT operations. Also current logging tools are at best not reliable since the anticipated bottom-hole temperature is often well above their operating limit. The Literature shows limited experimental data on drilling fluid properties beyond 350°F and 20,000 psig. The practice of extrapolation of fluid properties at some moderate level to extreme-HP/HT (XHP/HT) conditions is obsolete and could result in significant inaccuracies in hydraulics models. This research is focused on developing a methodology for testing drilling fluids at XHP/HT conditions using an automated viscometer. This state-of-the-art viscometer is capable of accurately measuring drilling fluids properties up to 600°F and 40,000 psig. A series of factorial experiments were performed on typical XHP/HT oil-based drilling fluids to investigate their change in rheology at these extreme conditions (200 to 600°F and 15,000 to 40,000 psig). Detailed statistical analyses involving: analysis of variance, hypothesis testing, evaluation of residuals and multiple linear regression are implemented using data from the laboratory experiments. I have developed the FluidStats program as an effective statistical tool for characterizing drilling fluids at XHP/HT conditions using factorial experiments. Results from the experiments show that different drilling fluids disintegrate at different temperatures depending on their composition (i.e. weighting agent, additives, oil/water ratio etc). The combined pressure-temperature effect on viscosity is complex. At high thresholds, the temperature effect is observed to be more dominant while the pressure effect is more pronounced at low temperatures. This research is vital because statistics show that well control incident rates for non- HP/HT wells range between 4% to 5% whereas for HP/HT wells, it is as high as 100% to 200%. It is pertinent to note that over 50% of the world’s proven oil and gas reserves lie below 14,000 ft subsea according to the Minerals Management Service (MMS). Thus drilling in HP/HT environment is fast becoming a common place especially in the Gulf of Mexico (GOM) where HP/HT resistant drilling fluids are increasingly being used to ensure safe and successful operations.
43

Experimental Characterization and Molecular Study of Natural Gas Mixtures

Cristancho Blanco, Diego Edison 2010 May 1900 (has links)
Natural Gas (NG) plays an important role in the energy demand in the United States and throughout the world. Its characteristics as a clean, versatile and a sustainable source of energy makes it an important alternative within the spectra of energy resources. Addressing industrial and academic needs in the natural gas research area requires an integrated plan of research among experimentation, modeling and simulation. In this work, high accuracy PpT data have been measured with a high pressure single sinker magnetic suspension densimeter. An entire uncertainty analysis of this apparatus reveals that the uncertainty of the density data is less that 0.05% across the entire ranges of temperature (200 to 500) K and pressure (up to 200 MPa). These characteristics make the PpT data measured in this study unique in the world. Additionally, both a low pressure (up to 35 MPa) and a high pressure (up to 200 MPa) isochoric apparatus have been developed during the execution of this project. These apparatuses, in conjunction with a recently improved isochoric technique, allow determination of the phase envelope for NG mixtures with an uncertainty of 0.45% in temperature, 0.05% in pressure and 0.12% in density. Additionally, an innovative technique, based upon Coherent Anti-Stokes Raman Scattering (CARS) and Gas Chromatography (GC), was proposed in this research to minimize the high uncertainty introduced by the composition analyses of NG mixtures. The collected set of P?T and saturation data are fundamental for thermodynamic formulations of these mixtures. A study at the molecular level has provided molecular data for a selected set of main constituents of natural gas. A 50-50% methane-ethane mixture was studied by molecular dynamics simulations. The result of this study showed that simulation time higher than 2 ns was necessary to obtain reasonable deviations for the density determinations when compared to accurate standards. Finally, this work proposed a new mixing rule to incorporate isomeric effects into cubic equations of state.
44

Development of a New Flame Speed Vessel to Measure the Effect of Steam Dilution on Laminar Flame Speeds of Syngas Fuel Blends at Elevated Pressures and Temperatures

Krejci, Michael 2012 May 1900 (has links)
Synthetic gas, syngas, is a popular alternative fuel for the gas turbine industry, but the composition of syngas can contain different types and amounts of contaminants, such as carbon dioxide, methane, moisture, and nitrogen, depending on the industrial process involved in its manufacturing. The presence of steam in syngas blends is of particular interest from a thermo-chemical perspective as there is limited information available in the literature. This study investigates the effect of moisture content (0 ? 15% by volume), temperature (323 ? 423 K), and pressure (1 ? 10 atm) on syngas mixtures by measuring the laminar flame speed in a newly developed constant-volume, heated experimental facility. This heated vessel also broadens the experimental field of study in the authors? laboratory to low vapor pressure fuels and other vaporized liquids. The new facility is capable of performing flame speed experiments at an initial pressure as high as 30 atm and an initial temperature up to 600 K. Several validation experiments were performed to demonstrate the complete functionality of the flame speed facility. Additionally, a design-of-experiments methodology was used to study the mentioned syngas conditions that are relevant to the gas turbine industry. The design-of-experiments methodology provided the capability to identify the most influential factor on the laminar flame speed of the conditions studied. The experimental flame speed data are compared to the most up-to-date C4 mechanism developed through collaboration between Texas A&M and the National University of Ireland Galway. Along with good model agreement shown with all presented data, a rigorous uncertainty analysis of the flame speed has been performed showing an extensive range of values from 4.0 cm/s to 16.7 cm/s. The amount of carbon monoxide dilution in the fuel was shown to be the most influential factor on the laminar flame speed from fuel lean to fuel rich. This is verified by comparing the laminar flame speed of the atmospheric mixtures. Also, the measured Markstein lengths of the atmospheric mixtures are compared and do not demonstrate a strong impact from any one factor but the ratio of hydrogen and carbon monoxide plays a key role. Mixtures with high levels of CO appear to stabilize the flame structure of thermal-diffusive instability. The increase of steam dilution has only a small effect on the laminar flame speed of high-CO mixtures, while more hydrogen-dominated mixtures demonstrate a much larger and negative effect of increasing water content on the laminar flame speed.
45

An Action Research for the Transformation of a Vocational High School into a Comprehensive High School- National Lungtan Vocational High School

Liou, Jau-Yi 27 August 2003 (has links)
The comprehensive high school is one of the tremendous reforms in the post-secondary education of our country to withstand the shift of times. The Ministry of Education adopted the suggestions from the seventh meeting of National Education and started to work intensively on the experimental curriculum of the comprehensive high school in 1996. Therefore, take National Lungtan vocational senior high school as an example to explore this kind of transformation of the formal education system. The aim of this study was to take Lungtan vocational senior high school as an example, and used action research to investigate the process of performing the transform of the comprehensive high school, to find out the difficulties and problems, and to solve its related problems. The findings are as follows: After the comprehensive high school has become one of the formal education systems, for the case of National Lungtan Vocational Senior High School of transforming to the comprehensive high school, this really corresponds with the mainstreams of education. The suitable and best transforming model is for the case of National Lungtan Vocational Senior High School: Under negotiating in advance and getting the common consensus with the faculty in a formal meeting, there are some valuable experiences we got, as follows: (1)The difficulties and policies of curriculum design: (a) The change of teaching hours and the problems of arranging the curricula¡Xto make the teachers who teach the vocational programs instruct the related subjects in order to meet the basic requirements. (b) According to the arrangement of the programs, it is necessary to divide the students into some groups so that it will meet the needs of students, parents, and the school. (2)The problems and solutions for the faculty: (a)Performing the plan of retirement will solve some problems of the faculty. (b)No sufficient teachers are in the academic subjects. To solve this problem, it is efficient to make use of resources around the school-community or hire more teachers from other schools. (c) It is important to solve the surplus for the teachers of professional and vocational subjects. For example, it will work out to make the teachers have advanced studies. (3)The plan and the way to handle the equipment: (a) Because there are no enough facilities to offer the current needs, increasing some professional classrooms reduces the deficiency. (b) The limitations of funds for operation. Thus, presenting a series of improving plans solves the insufficient problems. (c) Actively engaging in the related affairs or plans to get the funds and then to improve the equipment. According to the conclusions, there are some suggestions as follows: A. The strategies of transforming model for the case of National Lungtan Vocational Senior High School can provide some references for both the public and private high schools implementing the comprehensive high school. (1) The conductor¡¦s leading style (especially the principal) will be the key to success in implementing the transforming model. (2) How to transform is a crucial question so it is necessary to have a complete discussions and arrangement before making decisions. (3) With the suitable transforming model, it will reduce the number of the opposite teachers. (4) The suitable and best transforming model for the case of National Lungtan Vocational Senior High School will be more competitive among schools. (5) It is better to tend to the direction of community-united comprehensive high school. B. How to continue to impel the project of comprehensive high school for the case of National Lungtan Vocational Senior High School in the future. (1) For those performing the comprehensive schools, it is essential to get funds for operation in order to enlarge staff¡¦s allocation. (2) Schools should offer many opportunities of selecting classes and then students will have more room for developing their potential ability. Above all, it is better to adopt the middle curriculum. (3) Continue to advocate the ideas to parents and junior high school students. Meanwhile, pay attention to the evaluation for the performing process, and chase the common prospect. (4) Remain to explore the adjusting situation after graduating from the comprehensive high schools entering University.
46

Improvement on low-temperature deposited high-k materials by high-pressure treatment

Su, Hsuan-Hsiang 08 October 2008 (has links)
In this study, high-pressure oxygen (O2 and O3) technologies were employed originally to effectively improve the properties of low-temperature-deposited metal oxide dielectric films. In this work, 5 nm ultra-thin HfO2 and ZrO2 films were deposited by sputtering method at room temperature. Then, the low temperature high-pressure oxygen treatments at 150 ¢XC were used to replace the conventional high temperature annealing for HfO2 and ZrO2 improvement. From the experimental results, O3 produced by UV light illumination in O2 ambient has the superior passivation ability than O2, and it can further suppress leakage current density and improve capacitance characteristics. According to the XPS analyses, the absorption peaks of Hf-O and Zr-O bonding energies apparently raise and the quantity of oxygen in HfO2 and ZrO2 film also increases from XPS measurement. In addition, both the leakage current density of 5nm HfO2 and ZrO2 film can be improved to 10-8 A/cm2 at |Vg| = 3 V, and the conduction mechanisms were transferred from trap-assisted tunneling to thermal emission because of the significantly reduction of defects. All the experiment processes in this study, the temperatures were controlled below 150 ¢XC. The proposed low-temperature and high pressure O2 or O3 treatment for improving high-k dielectric films is novel and applicable for the future flexible electronics.
47

On the edge of chaos a Delphi study of the changing role of the secondary principal /

Goodwin, Rebecca H. January 2002 (has links)
Thesis (Ed. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 263 p. Vita. Includes abstract. Includes bibliographical references (p. 187-211).
48

Improved beam jitter control methods for high energy laser systems

Frist, Duane C. January 2009 (has links) (PDF)
Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Agrawal, Brij ; Kim, Jae Jun. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: High Energy Laser (HEL), beam control, Fast Steering Mirror (FSM), two axis gimbal, stabilization, video tracking, feedforward control, adaptive filter. Includes bibliographical references (p. 69). Also available in print.
49

Exploring the relationship between the perceived leadership style of secondary principals and the professional development practices of their teachers /

Persico, Mary, January 2001 (has links)
Thesis (Ph. D.)--Lehigh University, 2001. / Includes vita. Includes bibliographical references (leaves 171-196).
50

Secondary school prototype /

Wong, Shiu-tao, Stephen. January 2000 (has links)
Thesis (M. Arch.)--University of Hong Kong, 2000. / Includes special report study entitled: Modular co-ordination in building and precast concrete application. Includes bibliographical references.

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