Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 50 for “"Meteor"”.
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Adaptive methods for meteor burst communications
… power received by radio reflection from meteor trails, including applications of variable-rate coding and variable-rate transmission. For variable-rate coding, the code rate is changed periodically during the life of the trail in an attempt to match the rate to the instantaneous signal …
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The Urbana Meteor-Radar System: Design, Development, and First Observations
Made available in DSpace on 2014-12-12T20:54:27Z (GMT). No. of bitstreams: 1 7709027.pdf: 12037778 bytes, checksum: 55449b6f9a5d5999fd93248cb2d20256 (MD5) Previous issue date: 1976
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An analysis of IQSY meteor wind and geomagnetic field data,
… Institute of Technology, Dept. of Meteorology, 1970.
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The study of an adaptive bit rate modem for meteor scatter communications
Includes bibliographical references.
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Impact induced porosity of terrestrial impact craters : a gravity study of Meteor Crater.
… gathered and interpreted gravity anomaly data at Meteor Crater, and we used these data to constrain the porosity variations across Meteor Crater that were induced by the crater-forming impact event. We performed a gravity survey at the crater and merged these new data with legacy gravity survey …
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An Investigation of the Variability of Tides in the Upper Mesosphere (Meteor Radar)
A computer simulation of the Urbana, Illinois, meteor radar is performed to estimate the accuracy of the data analysis procedures in determining upper mesospheric tides. Various wind models such as planetary waves, gravity waves, and turbulence are tested and it is found that for reasonable values …
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Influence of Plasma Trails from Hypersonic Events on HF Radar Data Capture
Meteors enter earth's atmosphere with a great amount of kinetic energy. As a result of this atmospheric contact, many meteors will be burned up before they can make it to earth's surface, but not before they cause atmospheric disturbances. The SuperDARN HF radar is designed to measure the …
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Simultaneous observations of meteors and the equatorial electrojet at Jicamarca
Observations of meteor echoes at Jicamarca in August of 1990, 1991, and 1992 reveal some unusual properties. The echo durations are very long ($\sim$2 s to 3 minutes), radio wave scattering is non-specular (echoes are detected simultaneously over an $\sim$10 to 15 km altitude range centered about …
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On stress, strength, and failure in asteroids during planetary entry
… physical properties such as strength. Recovered meteorites provide some of the best evidence for these properties. However, their measured strengths are often orders of magnitude higher than those inferred from meteor observations. In this thesis, we seek to provide a full-field description of …
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Fluxes of Sporadic Meteoroids from Optical Measurements
… speed distribution, and the flux of the sporadic meteor sources using an electro-optical system. Data was recorded on two nights, April 27 and May 6, 2006, and the system was tested by measuring the flux of the eta Aquariid meteor shower. Eta Aquariid fluxes yielded ZHRs of 14.3 ± 4.5 meteors …
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Radiology Report Summarization With Large Language Models
… and 111.15% were observed in BLEU-4, ROUGE-L, METEOR, BERTScore, and F1-RadGraph, respectively. Similarly, the fine-tuned T5-Base model achieved BLEU-4, ROUGE-L, and F1-RadGraph scores of 31.25, 47.57, and 40.73—representing increases of 677.36%, 255.18%, and 337.31% over the base model. In the …
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Thermal Evolution of Moon
… surface temperatures;(2) identifying atmospheric meteor trails;(3) search for meteor impacts on the Moon surface. Out of the three this thesis focusses on experiment 1 and the results from this experiment could also help with the other experiments.</p> <p>We propose to use a thermal infrared …
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Lidar and Modeling Studies of the Mesospheric Iron and Sodium Layers
… metals are believed to be the product of meteoric ablation. Very thin and brief layers observed in our lidar data, attributed to recently ablated meteors, are used to examine this hypothesis. The altitude distribution of these trails is compared to a model of meteoric deposition, meteor …
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Investigation of the Winds and Electron Concentration Variability in the D Region of the Ionosphere by the Partial-Reflection Radar Technique
… technique to study the possible meteorological causes of the winter anomaly in the mesosphere at midlatitudes. Winds data obtained by the meteor-radar experiment at Urbana are also compared with electron concentration data measured at Urbana. A significant correlation is shown in …
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Lidar studies of sporadic sodium layers, gravity waves and density spectra in the mesopause and stratopause regions at Urbana and Arecibo
… are believed to be the first observations of meteor ablation trails with a lidar. Next, the simultaneous observations of a sporadic E layer by the Arecibo 430 MHz incoherent scatter radar and a sporadic Na layer by the UIUC CEDAR Na lidar are presented. The high correlation between the …
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Asteroid deflection campaign design integrating epistemic uncertainty
… avoidance, has been gaining interest with recent meteor or fly-by events, including the Chelyabinsk meteor that entered the Earth's atmosphere and exploded over Russia in 2013. Past or planned robotic missions to near-Earth asteroids are expected to provide an excellent opportunity to demonstrate …
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Comparative Life Cycle Assessment of CFC-replacement Compounds in Different Technical Applications
… properties by means of the mathematical model METEOR (METhod of Evaluation by ORder theory) was performed for 15 refrigerants i.e. chlorodifluoromethane (R22), difluoromethane (R32), pentafluoroethane (R125), 1,1,1-trifluoroethane (R143a), propene (R1270), ammonia (R717), R134a, R152a, R290, …
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Role of Planetary Wave-Tide-Gravity Wave Interactions In Whole Atmosphere Coupling
… events. The development of a new multi-static meteor radar at 30ºS, named Chilean Observation Network De MeteOr Radars (CONDOR), provides a key dataset for the present studies. Wind validation of this new radar system is performed across different sites and compared to a co-located sodium …
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Perchlorate Variations Over 300 Years: Influence of Human Activities, Volcanic Eruptions and Bolide Events
… suggest that a superbolide event, the Tunguska meteor explosion in 1908, may be primarily responsible for extraordinarily high perchlorate levels between 1908 and 1914. The breakup of the Tunguska meteor could have directly released perchlorate, or the increased aerosol/dust from the explosion …
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