In this thesis, there were four purposes. The first one was to investigate effects of nanoclays (NC) on the flammability behavior of polystyrene (PS). The second purpose was to investigate contribution of nanoclays to the flame retardancy performance of conventional phosphorus based flame retardant / triphenyl phosphate (TPP) and its synergist melamine cyanurate (MCA). For the third purpose contribution of nanoclays to the flame retardancy performance of another conventional halogenated flame retardant / brominated epoxy polymer (BE) and its synergist antimony trioxide (AO) was investigated. As the fourth purpose, effects of another nanoadditive / carbon nanotubes (CNTs) on the flammability behavior of PS with and without BE-AO flame retardant system was investigated. Materials were prepared via &ldquo / solution mixing&rdquo / method, while test specimens were shaped by compression and injection molding. Flammability behaviors were investigated by Mass Loss Cone Calorimeter (MLC), Limiting Oxygen Index (LOI) and UL-94 Vertical Burning tests. Other characterization techniques required in this thesis were / X-ray diffraction analyses, scanning and transmission electron microscopy, thermogravimetric analyses and tensile tests. It was revealed that use of nanoclays improved flame retardancy of PS significantly, mainly with &ldquo / condensed phase&rdquo / mechanism via formation of strong char barrier layers inhibiting mass and heat transfer. When nanoclays were used together with conventional flame retardant systems TPP-MCA and BE-AO, flame retardancy parameters improved further, this time due to the &ldquo / synergistic action&rdquo / of &ldquo / condensed phase mechanism&rdquo / of nanoclays and &ldquo / gas phase mechanism&rdquo / of the conventional systems. Use of carbon nanotubes also resulted in improvements in the flame retardancy of PS. However, &ldquo / condensed phase mechanism&rdquo / of CNTs were not as effective as the NCs, which might be due to the lower performance of 1D geometry (CNTs) compared to higher efficiency of 2D geometry (NC) in barrier formation. As an additional purpose, effects of mixing methods in the production of PS-Nanoclay composites were also investigated. It was seen that compared to &ldquo / solution mixing&rdquo / use of &ldquo / in-situ polymerization&rdquo / resulted in poorer flame retardancy parameters that might basically be due to residual monomers or oligomers left during polymerization.

Title from PDF of title page. / Document formatted into pages; contains 230 pages. / Thesis (M.S.M.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: A conical nozzle with two separate inlets within its top plate is analyzed. One of the inlets is in the center of the top plate, which is free to rotate, whereas the other inlet is positioned away from the center. The fluid entering through the outer inlet slot causes the top plate of the nozzle to spin. Several fluids including FC-77, FC-72, FC-87, and Methanol running at different flow rates were investigated to observe the effect that their particular properties have on the geometry of the fluid's free surface exiting the nozzle. Another variation performed was the geometry of the nozzle. The outer inlet slot was positioned at various radial distances along the top plate. For this nozzle, the top plate remained stationary and swirling was introduced to the fluid at the inlets. It was observed that the faster flow rates caused an increase in the free surface height and cone angle. / ABSTRACT: For the various radial locations of the outer inlet slot, it was noted that a position at approximately 75% of the nozzle radius produced the largest free surface height. The largest cone angle was produced when the outer inlet slot was positioned at the edge of the nozzle top plate. Another factor that increased the radial height and cone angle of the free surface was the working fluid used in the study. A larger Reynolds number produced a larger cone angle and larger free surface height (while a smaller Reynolds number produced a less significant cone angle and free surface height). / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Thesis (Ph. D.)--University of Chicago, The Divinity School, Dec. 2003. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 80-91).

Downhole seismic testing and seismic cone penetration testing (SCPT) have shown little change since the 1990’s, with essentially the same sensors, sources, test procedures and analytical methods being used. In these tests, the time differences of first-arrivals or other reference points early in the time-domain signals have been used to calculate shear and compression wave velocities in soil and rock layers. This time-domain method requires an operator to pick the first arrival or other reference point of each seismic wave in the time record. Picking these reference points correctly is critical in calculating wave velocities. However, picking these points in time records is time consuming and is not always easy because of low signal-to-noise ratios, especially in the case of shear waves which arrive later in the time record. To avoid picking reference points, a cross-correlation method is sometimes applied to determine travel times of the seismic waves, especially in traditional downhole testing. One benefit of the cross-correlation method is that it can be automated. The cross-correlation method is not, however, appropriate for evaluation other body wave characteristics such as wave dispersion and material damping. An alternate approach is to use frequency-domain analysis methods which are well suited for evaluating time changes between all types of waveforms measured at spatially different points. In addition, frequency-domain methods can be automated and attenuation measurements can also be performed. Examples of such testing procedures with Rayleigh-type surface waves in geotechnical earthquake engineering are the Spectral-Analysis-of-Surface-Waves (SASW) and Multi-Channel-Analysis-of-Surface-Waves (MASW) methods. In this research, an automated procedure for calculating body wave velocities that is based on frequency-domain analysis is presented. The basis for and an automated procedure to calculated body wave dispersion is also presented. Example results showing shear wave velocity and material damping measurements in the SCPT are presented. The objective of this study is to improve downhole seismic tests with boreholes, cone penetrometers or flat-plate dilatometers by developing a frequency-domain analysis method which overcomes many of the disadvantages of time-domain analyses. The frequency-domain method is called the Spectral-Analysis-of-Body-Waves (SABW) method. The SABW method does not require an operator to pick the first-arrival or other reference times. As a result, the shear wave velocities and wave dispersion can be calculated in real time using the interpretation method with an automatic calculation procedure, thus reducing human subjectivity. Also, the SABW method can be used to determine additional information from the dispersion curves such as the material damping ratio and an estimate of soil type based on the dispersion relationship. In this research, field SCPT measurements are presented as an example to illustrate the potential of the SABW method. Measurements with shear waves are highlighted because these measurements are most often required in geotechnical earthquake engineering studies. / text

Media use of hurricane graphics to apprise populations vulnerable to severe weather provides a persuasive demonstration of the importance and complexity of visual communication. Surprisingly little research, however, has explored how audiences interpret weather graphics. This study examined whether the general public and the National Weather Service share a common understanding of selected weather related terms and meaning of a NWS informational graphic. Using a coorientation model, general public responses to a questionnaire were compared to definitions prescribed by the NWS. Additionally, the public were asked questions to measure trust of the NWS as a credible and reliable source of severe weather information. Selected broadcast meteorologists were surveyed to measure their opinions of the NWS as well as to measure their perceptions of how the general public would respond to questions relating to knowledge of weather terms and graphics. Results revealed discrepancies between the intent of such graphics and audience interpretations. While the vast majority of respondents recognized the Tropical Cyclone Track Watch/Warning Graphic and understood much of the information it conveyed, study respondents did not seem to remember or understand the meaning of the terms Watch and Warning. While these terms or conditions are only one aspect of the graphic they represent critical information for populations at risk. Additionally, the results of this study indicate that weather forecasting professionals' perceptions of the public's understanding of the graphic are inaccurate. Results also show respondents generally rate the NWS as a reliable and competent agency but they do not consistently rate their local weather providers as well. Weather scientists' foremost concern may be the accuracy of their forecasts, but they also must consider the accuracy of the perceptions of those forecasts if they are to be effective in warning populations at risk of severe weather. These results have sobering implications for both governmental and private sources of emergency communication.

Modern image-guided surgery aids minimally-invasive, high-precision procedures that increase efficacy of treatment. This thesis investigates two research aims to improve precision and integration of intraoperative cone-beam CT (CBCT) imaging in guidance of head and neck (H&N) surgery. First, marker configurations were examined to identify arrangements that minimize target registration error (TRE). Best arrangements minimized the distance between the configuration centroid and surgical target while maximizing marker separation. Configurations of few markers could minimized TRE with more markers providing improved uniformity. Second, an algorithm for automatic registration of image and world reference frames was pursued to streamline integration of CBCT with real-time tracking and provide automatic updates per scan. Markers visible to the tracking and imaging systems are automatically co-localized and registered with equivalent accuracy and superior reproducibility compared to conventional registration. Such work helps the implementation of CBCT in H&N surgery to maximize surgical precision and exploit intraoperative image guidance.

Modern image-guided surgery aids minimally-invasive, high-precision procedures that increase efficacy of treatment. This thesis investigates two research aims to improve precision and integration of intraoperative cone-beam CT (CBCT) imaging in guidance of head and neck (H&N) surgery. First, marker configurations were examined to identify arrangements that minimize target registration error (TRE). Best arrangements minimized the distance between the configuration centroid and surgical target while maximizing marker separation. Configurations of few markers could minimized TRE with more markers providing improved uniformity. Second, an algorithm for automatic registration of image and world reference frames was pursued to streamline integration of CBCT with real-time tracking and provide automatic updates per scan. Markers visible to the tracking and imaging systems are automatically co-localized and registered with equivalent accuracy and superior reproducibility compared to conventional registration. Such work helps the implementation of CBCT in H&N surgery to maximize surgical precision and exploit intraoperative image guidance.

Naudojant įprastas 2D failų naršykles esant dideliems (>1000) failų medžiams, kyla problemų, kaip patogiai ir greitai tvarkyti bylas. Šio darbo tikslas yra pasiūlyti patogesnį failų pavaizdavimo būdą ir sukurti didelių medžių failų naršyklės 3D vizualizaciją. Jai iškelti panaudojamumo kriterijai, pagal juos apžvelgiant pavaizdavimo būdus pasirinkta kūginių medžių vizualizacija, aprašyti sistemos reikalavimai, pasirinkta technologija ir realizuotas sistemos prototipas. Sukurta sistema FSN tenkina iškeltus kriterijus ir yra tinkama didelių failų medžių pavaizdavimui. / It is not convenient to browse large file systems (more than 1000 files) using ordinary 2D file browsers. The purpose of this paper is to suggest file tree visualization, suitable for large file trees and implement 3D file system browser prototype. According to the needed browser tasks, there was selected cone tree visualization, was defined specification, selected suitable technology and implemented 3D browser prototype. This system implemented all specified tasks and is suitable for large file tree visualization.

Cobalt 60 (Co-60) radiation therapy is a simple and reliable method of treating cancer by irradiating treatment volumes within the patient with high energy gamma rays. Medical linear accelerators (linacs) began to replace Co-60 units during the 1960’s in more developed countries, but Co 60 has remained the main source of radiotherapy treatment in less developed countries around the world. As a result, technological advancements made in more developed countries to deliver more precise radiation treatment that improves patient outcome have not been clinically applied to Co-60 machines. The medical physics group at the Cancer Centre of Southeastern Ontario has shown that these same technological advancements can be applied to Co-60 machines which would increase the accessibility of these modern improvements in radiotherapy treatment. However, for these modern treatments to improve patient outcome they require more precise localization of the patient prior to therapy. In more developed countries, this is currently provided by comparing computed tomography (CT) used for treatment planning with images acquired on the linac immediately before treatment. In the past decade, cone-beam CT (CBCT) has been developed to provide 3D CT images of the patient immediately prior to treatment on a linac. This imaging modality would also be ideal for patient localization when conducting modern Co-60 treatments since it would only require the addition of an imaging panel to produce CBCT images using the Co-60 source. A prototype Co-60 CBCT imaging system was implemented and characterized. Image noise, contrast, spatial resolution, and artifacts were studied. Algorithms to reduce the image artifacts were implemented and found to improve perceived image quality. The imaging system was found to have a ~1.8 mm high-contrast spatial resolution and the ability to detect 3 cm low-contrast soft-tissue structures in water. Anthropomorphic phantoms were also imaged and the observed anatomy in Co-60 CBCT images was comparable to kilovoltage CT. These results are comparable to clinically relevant linac-based CBCT using high energy X rays of similar energies to Co-60 gamma rays. This suggests that Co-60 CBCT should be able to provide the necessary images to localize patients for modern Co-60 radiation treatments. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2010-11-30 13:40:07.61