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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.
1

Development of a phased-array ionospheric imaging system

Bruce, Nicholas 10 April 2019 (has links)
A novel approach to ionospheric imaging with the purpose of weather/distaster prediction and climate study is introduced. This feasibility study combines traditional material imaging techniques with high frequency (HF) radio via SDR (software defined radio) systems in order to capture three-dimensional images of the atmosphere. An experiment is devised and the necessary instrumentation built in order to capture coherent images of the ionosphere. The experimental results show these three-dimensional images as well as a novel approach to measuring ionospheric height. The novelty of the research comes from the use of a closely spaced phased-array of radio antennas in conjunction with a post-correlation beamformer repurposed from radio astronomy. Experiments were run at both the University of Victoria and DRAO (Dominion Radio Astrophysical Observatory), the results which led to a successful proposal for extending the research onto a larger array with support from research groups in New Mexico. / Graduate
2

Reappraisal of geophysical phenomena and associated portents in the classical world

Maxwell Miller Unknown Date (has links)
ABSTRACT Many unusual phenomena in nature were recorded from the regions bordering the Mediterranean Sea from the second millennium BC up to AD 600. The ancient sources interpreted these as prodigies, messages from the gods, but rarely discussed their causes. Numerous reports of these portents were viewed as the illusions of eyewitnesses or the fabrications of ancient literary sources. Many modern authors have interpreted these portents as fabulous, or as astronomical or meteorological events. This thesis examines the portents that occur in the atmosphere, biosphere, lithosphere and hydrosphere and proposes that many are geophysical phenomena caused by tectonic activity, in particular earthquakes and volcanoes. Modern research on these incidents is examined to identify characteristics and causes, and texts from ancient philosophers and natural historians are investigated to see whether they were aware of these natural occurrences and if so, how they were produced. Portents that possess the characteristics of seismically-induced lights, cloud, fog, storms, anomalous animal behaviour, noises, and hydrological changes are collated in order to discuss individual events. Where possible, ancient examples are compared with modern well-documented episodes with the same features. In a majority of cases, these events have recurred in the same locations at later times. The proposal that many of these phenomena are caused by seismic activity offers an alternative to the suggestions of many modern scholars, who ascribe many of the luminous events to lightning, meteors or comets and some sonics to exploding meteors or thunderstorms. This reappraisal of the ancient portents vindicates the seemingly fantastic reports that occur in the ancient texts, especially some of the poetic or religious sources, and rehabilitates the reputation of the authors who have documented these events. In the process it also adds to the catalogue of geophysical phenomena caused by earthquakes in the classical world.

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