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Analysis of the performance of a loop radiator and a spiral applicator at low RF frequencies
Title
Analysis of the performance of a loop radiator and a spiral applicator at low RF frequencies.
Creator
Roman, John M., Florida Atlantic University, Ungvichian, Vichate, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
This thesis addresses the electromagnetic analyses of two structures. The first structure, a low frequency loop antenna recommended for use by national standards on electromagnetic compatibility (EMC), is incorrectly specified to have the same voltage to magnetic field conversion ratio (antenna factor) when used with a 50 ohm receiver in lieu of a high impedance type ($>$600 ohm). Two independent measurement sets were performed to demonstrate the prevailing discrepancy, and a corrected...
Show moreThis thesis addresses the electromagnetic analyses of two structures. The first structure, a low frequency loop antenna recommended for use by national standards on electromagnetic compatibility (EMC), is incorrectly specified to have the same voltage to magnetic field conversion ratio (antenna factor) when used with a 50 ohm receiver in lieu of a high impedance type ($>$600 ohm). Two independent measurement sets were performed to demonstrate the prevailing discrepancy, and a corrected antenna factor is presented for use with a 50 ohm receiver. The second structure, a partial spiral "pancake" applicator used to generate high EM fields in its vicinity, was evaluated for its (induction) reactive near-field electromagnetic characteristics. Construction of an induction zone measurement system including the development of an electrically small electric field is described. Measured data on three dimensional EM field contours over the face of the applicator, are presented.
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Date Issued
1998
PURL
http://purl.flvc.org/fcla/dt/15535
Subject Headings
Radio--Antennas--Design and construction, Electromagnetic fields, Electromagnetic measurements
Format
Document (PDF)
Analytical and experimental evaluation of the magnetic fields induced by buried and overhead high-voltage power-lines
Title
Analytical and experimental evaluation of the magnetic fields induced by buried and overhead high-voltage power-lines.
Creator
Lordan, Richard Joseph., Florida Atlantic University, Neelakanta, Perambur S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
This thesis is concerned with the measurement of magnetic field components induced above the earth's surface by three classes of high-voltage power transmission lines supplemented by algorithmic formulations: The first system refers to three-phase lines housed in a plastic (PVC) conduit, buried directly in the soil or encased in a concrete duct. The second category refers to a similar buried system, but encased in an iron/steel pipe. The third transmission line is an overhead three-phase...
Show moreThis thesis is concerned with the measurement of magnetic field components induced above the earth's surface by three classes of high-voltage power transmission lines supplemented by algorithmic formulations: The first system refers to three-phase lines housed in a plastic (PVC) conduit, buried directly in the soil or encased in a concrete duct. The second category refers to a similar buried system, but encased in an iron/steel pipe. The third transmission line is an overhead three-phase system. Using boundary-value approach, approximate (closed-form) expressions are obtained for the magnetic field above the earth's surface caused by each of the systems indicated. Calculated results are compared with experimental data compiled from field experiments.
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Date Issued
1990
PURL
http://purl.flvc.org/fcla/dt/14660
Subject Headings
Electric lines--Environmental aspects, Electromagnetic fields--Measurement, Electric fields--Measurement
Format
Document (PDF)
Characterizing magnetic noise of AUV for use in towed magnetometer study of internal waves
Title
Characterizing magnetic noise of AUV for use in towed magnetometer study of internal waves.
Creator
Tilley, Dylan., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
As part of a project to study internal waves, FAU plans to utilize an AUV to tow a magnetometer to study electromagnetic signatures from internal waves. This research is focused on the electromagnetic noise issues related to using an AUV to tow the magnetic sensor package. There are active sources of electromagnetic noise caused by an AUV that are present in addition to those induced by the Earth's magnetic field and permanent magnets. To characterize the magnetic noise associated with the...
Show moreAs part of a project to study internal waves, FAU plans to utilize an AUV to tow a magnetometer to study electromagnetic signatures from internal waves. This research is focused on the electromagnetic noise issues related to using an AUV to tow the magnetic sensor package. There are active sources of electromagnetic noise caused by an AUV that are present in addition to those induced by the Earth's magnetic field and permanent magnets. To characterize the magnetic noise associated with the AUV magnetometer tow system, the various active source elements were identified, the orientation sensitivity of the sensors being used was determined, and the magnetic anomaly of a similar AUV which may be eventually be used in a magnetic sensing arrangement was measured. The results are used to show the proposed sensing arrangement will likely not achieve the necessary sensitivity to measure subtle internal wave signals.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3352881
Subject Headings
Automatic control, Mathematical models, Electromagnetic measurements, Fluctuations (Physics), Oceanographic submersibles, Underwater acoustics
Format
Document (PDF)
directionality of noise created by turbulent flow over roughness
Title
The directionality of noise created by turbulent flow over roughness.
Creator
Kaufman, Gerard P., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Flow over a rough surface is known to radiate sound as a dipole source that is directional. In order to better understand this source, measurements are being made in a wind tunnel using a microphone array. The measurements collected by a microphone array are beamformed to give a source image and can be deconvolved with an assumed point spread function in order to obtain the source levels. This thesis considers alternative analysis algorithms that can be used to analyze wind tunnel data. Only...
Show moreFlow over a rough surface is known to radiate sound as a dipole source that is directional. In order to better understand this source, measurements are being made in a wind tunnel using a microphone array. The measurements collected by a microphone array are beamformed to give a source image and can be deconvolved with an assumed point spread function in order to obtain the source levels. This thesis considers alternative analysis algorithms that can be used to analyze wind tunnel data. Only numerical examples of how these algorithms work will be presented and the analysis of real data will be considered in later studies. It will be shown how estimates can be made of the source directivity by comparing the measured data with a theoretical source model and minimizing the error between the model and the measurements.
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Date Issued
2011
PURL
http://purl.flvc.org/FAU/3171394
Subject Headings
Electromagnetic fields, Signal processing, Digital techniques, Noise control, Adaptive signal processing, Acoustic emission, Measurement
Format
Document (PDF)
Simulating the dynamic interaction of an AUV and towed magnetometer
Title
Simulating the dynamic interaction of an AUV and towed magnetometer.
Creator
Miller, Lea Gabrielle., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
A magnetometer with a sensitivity of 0.01nT will be towed through the thermocline by a 2.87 meter long, 0.533 meter diameter autonomous underwater vehicle (AUV) to measure the magnetic fluctuations generated by oceanic internal waves. At this point, no research has been found that suggests towed magnetometer measurements have been done using an AUV. Simulations of the AUV, tow cable, and towfish are performed to provide an understanding of the effects of changing different input parameters,...
Show moreA magnetometer with a sensitivity of 0.01nT will be towed through the thermocline by a 2.87 meter long, 0.533 meter diameter autonomous underwater vehicle (AUV) to measure the magnetic fluctuations generated by oceanic internal waves. At this point, no research has been found that suggests towed magnetometer measurements have been done using an AUV. Simulations of the AUV, tow cable, and towfish are performed to provide an understanding of the effects of changing different input parameters, such as towing speed (0.5-2m/s), cable length (5-15m), vehicle trajectory (circle and vertical zig zag maneuvers), and current (0.25-1.25m/s). The AUV-cabletowfish system and equations of motion needed for the simulations are described herein. Results show that a 5m tow cable provides better towfish maneuvering than the longer cable lengths. High towfish pitch angle is decreased by decreasing the distance between CG and CB. Surface currents speed of 0.25m/s change the AUV and towfish circle maneuver to a spiral trajectory, while 1.25m/s current speed cause a zig zag trajectory.
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Date Issued
2011
PURL
http://purl.flvc.org/FAU/3318670
Subject Headings
Automatic control, Mathematical models, Electromagnetic measurements, Fluctuations (Physics), Oceanographic submersibles, Computer simulation
Format
Document (PDF)
Influence of the boundaries on the acoustic scattering by a submerged target
Title
Influence of the boundaries on the acoustic scattering by a submerged target.
Creator
Charmes, Emmanuel., Florida Atlantic University, Beaujean, Pierre-Philippe, Cuschieri, Joseph M.
Abstract/Description
In shallow water or fluid half-space, the acoustic scattering from a target is significantly different from that of an unbounded medium, due to the multiple reflections occurring between the target and the boundaries. The purpose of this thesis is to investigate the influence of the boundaries on the acoustic scattering of a rigid sphere by means of a superposition method. A minimum number of point sources necessary to accurately model the scattered field is determined in the case of a free...
Show moreIn shallow water or fluid half-space, the acoustic scattering from a target is significantly different from that of an unbounded medium, due to the multiple reflections occurring between the target and the boundaries. The purpose of this thesis is to investigate the influence of the boundaries on the acoustic scattering of a rigid sphere by means of a superposition method. A minimum number of point sources necessary to accurately model the scattered field is determined in the case of a free medium, a fluid half-space and a waveguide. The free field symmetry vanishes due to the presence of boundaries and, at particular frequencies or scatterer depths, a significant change in the magnitude and spatial distribution of the scattered field occur. In an unbounded medium or fluid half space, the superposition method is shown to give similar results to analytical formulations found in the literature, provided enough point sources are used.
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Date Issued
2005
PURL
http://purl.flvc.org/fcla/dt/13211
Subject Headings
Electromagnetic waves--Scattering, Acoustical engineering, Sound-waves--Measurement, Wave-motion, Theory of
Format
Document (PDF)
Comparing salinity models in Whitewater Bay using remote sensing
Title
Comparing salinity models in Whitewater Bay using remote sensing.
Creator
Selch, Donna, Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description
This study compared models that used remote sensing to assess salinity in Whitewater Bay. The quantitative techniques in this research allow for a less costly and quicker assessment of salinity values. Field observations and Landsat 5 TM imagery from 2003-2006 were separated into wet and dry seasons and temporally matched. Interpolation models of Inverse Distance Weighting and Kriging were compared to empirical regression models (Ordinary Least Squares and Geographically Weighted Regression -...
Show moreThis study compared models that used remote sensing to assess salinity in Whitewater Bay. The quantitative techniques in this research allow for a less costly and quicker assessment of salinity values. Field observations and Landsat 5 TM imagery from 2003-2006 were separated into wet and dry seasons and temporally matched. Interpolation models of Inverse Distance Weighting and Kriging were compared to empirical regression models (Ordinary Least Squares and Geographically Weighted Regression - GWR) via their Root Mean Square Error. The results showed that salinity analysis is more accurate in the dry season compared with the wet season. Univariate and multivariate analysis of the Landsat bands revealed the best band combination for salinity analysis in this local area. GWR is the most conducive model for estimating salinity because field observations are not required for future predictions once the local formula is established with available satellite imagery.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3356015
Subject Headings
Water quality, Measurement, Marine ecology, Remote sensing, Electromagnetic interactions, Water-supply
Format
Document (PDF)