Current Search: conical (x)
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Title
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ANALYIS OF AIRBORNE MICROWAVE POLARIMETRIC RADIOMETER MEASUREMENTS IN THE PRESENCE OF DYNAMIC PLATFORM ATTITUDE ERRORS.
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Creator
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Kabore, Jean Yves, Jones, Linwood, University of Central Florida
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Abstract / Description
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There are numerous applications for airborne imaging systems in remote sensing, and this thesis deals with a new microwave polarimetric radiometer technique for inferring ocean surface wind direction [3, 5, 7]. This technique is based upon the anisotropy of the polarized ocean blackbody emissions at microwave frequencies relative to the azimuth angle between the microwave radiometer antenna "look" direction and the direction of the wind. Because of the weak wind direction signature, it is...
Show moreThere are numerous applications for airborne imaging systems in remote sensing, and this thesis deals with a new microwave polarimetric radiometer technique for inferring ocean surface wind direction [3, 5, 7]. This technique is based upon the anisotropy of the polarized ocean blackbody emissions at microwave frequencies relative to the azimuth angle between the microwave radiometer antenna "look" direction and the direction of the wind. Because of the weak wind direction signature, it is important that all systematic brightness temperature (Tb) errors be eliminated, especially those that vary with the radiometer antenna scan position (look direction). This can be accomplished either in hardware implementation or through data processing corrections. Unfortunately, the misalignment of the axis of rotation for a conical-scanning imager can introduce such azimuthally dependent errors of significant magnitude. As the title suggests, the analysis of the resulting Tb errors caused by static and dynamic time-varying aircraft attitude errors is the main thrust of this thesis. In this thesis, we present analytical models developed to account for platform attitude changes on measured ocean microwave brightness temperature collected by a conically scanning radiometer. Data processing procedures for removing unwanted variations in ocean brightness temperatures are outlined. The analytical models are validated by making comparisons between modelled and measured Tb's obtained by the Conically Scanning Two-Look Airborne Radiometer (C-STAR). Results demonstrated that the analytical Tb model can accurately predict the measured polarized Tb's under actual flight conditions.
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Date Issued
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2006
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Identifier
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CFE0000926, ucf:46748
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000926
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Title
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STUDY OF DISCHARGE COEFFICIENT AND TRENDS IN FILM COOLING EFFECTIVENESS OF CONICAL HOLES WITH INCREASING DIFFUSION ANGLES.
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Creator
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Zuniga, Humberto, Kapat, Jayanta, University of Central Florida
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Abstract / Description
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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...
Show morePrevious 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 8º, 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.
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Date Issued
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2006
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Identifier
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CFE0001492, ucf:47087
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001492
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Title
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DEVELOPMENT OF THEORETICAL AND COMPUTATIONAL METHODS FOR THREE-BODY PROCESSES.
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Creator
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Blandon Zapata, Juan, Kokoouline, Viatcheslav, University of Central Florida
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Abstract / Description
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This thesis discusses the development and application of theoretical and computational methods to study three-body processes. The main focus is on the calculation of three-body resonances and bound states. This broadly includes the study of Efimov states and resonances, three-body shape resonances, three-body Feshbach resonances, three-body pre-dissociated states in systems with a conical intersection, and the calculation of three-body recombination rate coefficients. The method was applied...
Show moreThis thesis discusses the development and application of theoretical and computational methods to study three-body processes. The main focus is on the calculation of three-body resonances and bound states. This broadly includes the study of Efimov states and resonances, three-body shape resonances, three-body Feshbach resonances, three-body pre-dissociated states in systems with a conical intersection, and the calculation of three-body recombination rate coefficients. The method was applied to a number of systems. A chapter of the thesis is dedicated to the related study of deriving correlation diagrams for three-body states before and after a three-body collision. More specifically, the thesis discusses the calculation of the H+H+H three-body recombination rate coefficient using the developed method. Additionally, we discuss a conceptually simple and effective diabatization procedure for the calculation of pre-dissociated vibrational states for a system with a conical intersection. We apply the method to H_3, where the quantum molecular dynamics are notoriously difficult and where non-adiabatic couplings are important, and a correct description of the geometric phase associated with the diabatic representation is crucial for an accurate representation of these couplings. With our approach, we were also able to calculate Efimov-type resonances. The calculations of bound states and resonances were performed by formulating the problem in hyperspherical coordinates, and obtaining three-body eigenstates and eigen-energies by applying the hyperspherical adiabatic separation and the slow variable discretization. We employed the complex absorbing potential to calculate resonance energies and lifetimes, and introduce an uniquely defined diabatization procedure to treat X_3 molecules with a conical intersection. The proposed approach is general enough to be applied to problems in nuclear, atomic, molecular and astrophysics.
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Date Issued
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2009
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Identifier
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CFE0002669, ucf:48225
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002669