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Analysis Of The Day Side Equatorial Anomaly, Jayaprabha Shankar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Equatorial Ionization Anomaly (EIA) is a region of peak plasma density found at ± 10 ◦ to 20 ◦ magnetic latitudes at F-region altitudes. In 2002, NASA launched the Global Ultra Violet Imager (GUVI), which can observe the EIA at various local times, longitudes, and seasons by the glow of the recombining electrons and ions in the plasma. This thesis presents the observations of the geomagnetic quiet time EIA and its global behavior at all local times using 1356 ˚A radiance data from high altitude GUVI limb scans. Limb data is prepared for analysis using reduction techniques that remove from …

Design Of A Low-Power Automatic Wireless Multi-Logger Networking Device, Kelly S. Lewis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Virtually every industry and discipline (e.g., mining, pharmaceutical, construction, agriculture, reclamation, etc.) is finding applications for wireless data acquisition for monitoring and managing processes and resources. Two sectors, namely agriculture and environmental research, are seeking ways to obtain distributed soil and plant measurements over larger areas like a watershed or large fields rather than a single site of intensive instrumentation (i.e., a weather station). Wireless sensor networks and remote sensing have been explored as a means to satisfy this need. Commercial products are readily available that have remote wireless options to support distributed senor networking. However, these systems have been …

A Formal Approach To Specifying And Verifying Spacecraft Behavior, Allan I.S. Mcinnes

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Process algebra can provide spacecraft designers with a mathematical formalism for specifying, understanding, analyzing, and verifying spacecraft system behavior. Although it is standard practice to mathematically model and analyze the subsystems of a spacecraft to ensure that they will function correctly when built, the system-level behavior of the spacecraft is generally understood in much less rigorous terms. This leaves the spacecraft system vulnerable to design errors which may not become apparent until the integration and test phase, when design changes are most expensive. In this dissertation, we develop a formal approach to engineering spacecraft behavior, based on mathematical models of …

Application Of The Relevance Vector Machine To Canal Flow Prediction In The Sevier River Basin, John T. Flake

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This work addresses management of the scarce water resource for irrigation in arid regions where significant delays between the time of order and the time of delivery present major difficulties. Motivated by improvements to water management that will be facilitated by an ability to predict water demand, this work employs a data-driven approach to developing canal flow prediction models using the Relevance Vector Machine (RVM), a probabilistic kernel-based learning machine. Beyond the RVM learning process, which establishes the set of relevant vectors from the training data, a search is performed across model attributes including input set, kernel scale parameter, and …

Tropospheric Spectrum Estimations Comparing Maximum Likelihood With Expectation Maximization Solutions And Fast Fourier Transforms, Stanley James Wellard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The FIRST program (Far Infrared Spectroscopy in the Troposphere) was created as an Instrument Incubator Program (IIP) by NASA Langley to demonstrate improved technology readiness levels (TRLs) for two technologies needed in the design of new imaging Fourier transform spectrometers (IFTS). The IIP IFTS was developed at the Space Dynamics Laboratory and flown to an altitude of 103,000 feet on an instrumented NASA balloon payload. The sensor collected approximately 15,000 interferograms during its 6-hour flight.

Fourier transforms (FFT) produced acceptable results except for noise equivalent temperature differences (NETD) that were five times higher than goal and inconclusive transforms at seven …

Langmuir Probe Measurements In The Ionosphere, Aroh Barjatya

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Electric probes have been the primary instruments for the in situ investigation of plasma parameters in the Earth’s ionosphere. This dissertation is a compendium of three papers, each dealing with a separate spacecraft that carried one or more instruments based on the electric probe technique.

The first paper presents data from the Sudden Atom Layer sounding rocket that carried an RF Impedance Probe, a DC fixed-bias Langmuir Probe (DCP), and an Electric Field Probe. The combined dataset indicates a case of payload surface charging, the causes of which are investigated within the paper. A generic circuit model is developed to …