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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.
11

Nonlinear State Estimation of the Ionosphere as Perturbed by the 2017 Great American Eclipse

Sauerwein, Kevin Lee 11 February 2019 (has links)
The 2017 Great American Eclipse provided an excellent opportunity for scientists and engineers to study the ionosphere. The dynamics of the ionosphere are affected by the amount of solar radiation it receives and a total solar eclipse produces a short perturbation to the incoming solar radiation. Analyzing how the ionosphere reacts to this type perturbation could lead to new levels of understanding of it. This study develops a nonlinear filter that estimates the state of the ionosphere's 3-D electron density profile given total electron content (TEC) measurements from dual-frequency GPS receivers located on the ground and on low-Earth-orbiting spacecraft. The electron density profile is parameterized by a bi-quintic latitude/longitude spline of Chapman Profile parameters that define the vertical electron density profile. These Chapman parameters and various latitude and longitude partial derivatives are defined at a set of latitude/longitude spline grid points. Bi-quintic interpolation between the points defines the parameters' values and the corresponding Chapman profiles at all latitude/longitude points. The Chapman parameter values and their partial derivatives at the latitude/longitude spline nodes constitute the unknowns that the nonlinear filter estimates. The filter is tested with non-eclipse datasets to determine its reliability. It performs well but does not estimate the biases of the receivers as precisely as desired. Many attempts to improve the filter's bias estimation ability are presented and tried. Eclipse datasets are input to the filter and analyzed. The filter produced results that suggest that the altitude of peak electron density increased significantly near and within the eclipse path and that the vertical TEC (VTEC) was drastically decreased near and within the eclipse path. The changes in VTEC and altitudes of peak electron density caused by the eclipse leave a lasting effect that alters the density profile for anywhere from 15 minutes to several hours. / MS / The 2017 Great American Eclipse garnered much attention in the media and scientific community. Solar eclipses provide unique opportunities to observe the ionosphere’s behavior as a result of irregular solar radiation patterns. Many devices are used to measure this behavior, including GPS receivers. Typically, GPS receivers are used to navigate by extracting and combining carrier phase and pseudorange data from signals of at least four GPS satellites. When the position of a GPS receiver is well-known, information about the portion of the ionosphere that the signal traveled through can be estimated from the GPS signals. This estimation procedure has been done with ground-based and orbiting GPS receivers. However, fusing the two data sources has never been done and will be a primary focus of this study. After demonstrating the performance of the estimation algorithm, it is used to estimate the state of the ionosphere as it was perturbed by the 2017 Great American Eclipse.
12

Conductivity Modulation of Magnetosphere-Ionosphere Coupling

Coyle, Shane 14 May 2024 (has links)
Earth's ionosphere is a region of the upper atmosphere that consists of an energetic and electromagnetically reactive plasma. This region plays an important role in over-the-horizon and satellite radio communications, satellite orbits, and can electrically couple into human infrastructure like pipelines and power cables. Activity in the ionosphere is tightly coupled to the near-Earth space plasma region called the magnetosphere. This region is formed by interactions between the energetic particle outflow from the sun called the Solar Wind and Earth's magnetic field. Models of the coupling between these regions typically take a "sun to mud" perspective, as mass and energy from the sun are transferred into the magneto- sphere and ultimately into the upper atmosphere. However, the ionosphere also receives energy directly from ultra-violet radiation from the solar surface. This radiation is the nominal source of ionization in the upper atmosphere, but certain celestial events alter the magnitude of radiation that reaches the upper atmosphere. In the case of a solar eclipse, the moon directly shields a large portion of the Earth from solar radiation. This decreases both the temperature and ionization rate of the upper atmosphere, which in turn decreases the conductivity. A solar flare on the other hand increases the available ionizing energy, and consequently increases the conductivity of the ionosphere. Because the ionosphere is electrically coupled to the magnetosphere, changes in conductivity must necessarily affect the way that coupling occurs. In Chapters 1 and 3, we introduce some of the instrumen- tation used in observing magnetosphere-ionosphere coupling dynamics, as well as some of the difficulties associated with remote instrument operations in the high-latitude regions of Earth. Chapter 4 presents a case study of an Antarctic total solar eclipse, in which magnetic waves are observed from both northern and southern polar regions. The body of work in Chapter 5 suggests that large spatial scale variations in ionospheric conductivity related to solar eclipses are associated with geomagnetic substorms. All together, the research herein highlights the importance of considering ionospheric conductivity as a controlling parameter for magnetosphere-ionosphere coupling. / Doctor of Philosophy / Earth's upper atmosphere consists of an energetic and electromagnetically reactive plasma. This region plays an important role in over-the-horizon and satellite radio communications, and can impact human infrastructure. Activity in this region is influenced by plasma in space near Earth. This region is formed by interactions between energetic particles from the sun and Earth's magnetic field. It is occasionally the case that this near-Earth plasma is disturbed and rapidly moves into the upper atmosphere, resulting in brilliant auroral displays. One of the important factors that controls how this plasma and energy moves is the conductivity of the upper atmosphere region. This varies with latitude and season, but also changes more rapidly during special solar events. In the case of a solar eclipse, the moon directly shields a large portion of the Earth from solar radiation. This decreases both the temperature and ionization rate of the upper atmosphere, which in turn decreases conductivity. A solar flare on the other hand increases conductivity. In Chapters 2 and 3, we introduce some of the instruments used to observe the upper atmosphere plasma regions, as well as some of the difficulties associated with remote instrument operations in the high-latitude regions of Earth. Chapter 4 presents a case study of an Antarctic total solar eclipse, in which magnetic waves are observed from both northern and southern polar regions. Chapter 5 suggests that solar eclipses are associated with the previously mentioned plasma transfers from near-Earth space into the atmosphere. All together, the research herein highlights the importance of considering conductivity as a controlling parameter for energy and plasma transfer in the two regions.
13

Images of accretion discs in cataclysmic variables

Billington, Ian Michael January 1995 (has links)
No description available.
14

Optical and EUV observations of the solar atmosphere

Gallagher, Peter Thomas January 1999 (has links)
No description available.
15

Podpora vývoje rozšíření PHP CMS / Tools for PHP CMS extension development

Schmied, Martin January 2011 (has links)
This thesis seeks to improve the development process of open source content management system extensions with particular focus on functional extensions of Joomla CMS. It starts by analyzing current open source CMS market to conclude that most of it is dominated by systems implemented in the PHP programming language. Standard tools used throughout the PHP development process are then analyzed to show that fully-featured integrated development environments are not used as often as with compiled languages. It's shown, however, that modern open source IDEs can deliver performance gains even when used for development in a scripting language. The focus is then shifted from general purpose PHP development to the specifics of CMS extension development. Three major open source systems (WordPress, Drupal and Joomla) are presented with focus on their extensibility. It's demonstrated that some features of Joomla's module system, which are not present in the other systems in comparison, are making it much harder to establish an efficient development workflow that would take full advantage of an IDE. Two recommended workflows for Joomla extension development are then presented while pointing out their disadvantages. Based on this analysis, a new development workflow is designed incorporating yet-to-be-developed functional extensions of Eclipse IDE to solve the problems. The Eclipse platform is then described, pointing out some key technologies used to implement these functional extensions. Finally, major components of the implementation are described.
16

Nástroj pro návrh čipu v UML / Tool for Chip Design in UML

Srna, Pavol January 2010 (has links)
This paper deals with the creation of the tool for chip design in UML. The intention of this work is to present the news in the UML language version 2.0, that can be possibly used for modeling of embedded systems. Furthermore, it deals with the possibility and method of modeling in the Eclipse environment and it focuses on the Eclipse Modeling Framework. This work explains the principle of developing of graphical editors based on GMF used fully by developing tool. Finally, it discusses the chosen solution.
17

Multiwavelength studies of accretion discs and coronae in interacting binary stars

Ioannou, Zacharias January 2000 (has links)
No description available.
18

RMA: A Pattern Based J2EE Development Tool

Chen, Jun January 2004 (has links)
The development process for creating J2EE web applications is complex and tedious, and is thus error prone. The quality of a J2EE web application depends on correctness of code as well as the efficiency and flexibility of its architecture. Although the J2EE specification has promised to hide the distributed nature of the application, application developers still have to be aware of this fact in both the design (architecture) and implementation (code) perspectives. In this thesis, we present the detailed design of our pattern-based J2EE development tool, RoadMapAssembler (RMA). RMA demonstrates how patterns can be used to generate efficient architectural code while also hiding the deployment logic and distributed nature of J2EE applications in the implementation perspective. Furthermore, it shows the generation of a J2EE framework as a process of assembling patterns in an incremental fashion using known inter-pattern relationships.
19

Eclipses and penumbra

Beyer, Day McMaster 01 January 2019 (has links)
“Eclipses” orchestrates the movements of human beings as celestial bodies—as wandering beings that emit waves, cycle in orbit, and create shadows. Subtle microtonal movements, or retunings of the same pitch, tell the story of gradual planetary motion leading to the drama of the eclipse. In the dimmed light of a solar eclipse, even the most familiar surroundings seem unfamiliar and strange. The harmonic material of “Eclipses” was composed using the Rainbow Harmony Matrix, a MaxMSP-based mouse and keyboard interface designed for real-time interaction with a 2D colorized pitch space defined by Just Intonation ratios. The most difficult coding in this patch was completed thanks to the generous help of Jean-François Charles. The spatialization and color-coding of Just Intonation pitches provided by the Rainbow Harmony Matrix proved invaluable to organizing harmonic and melodic material. Elements of rhythm, timbre, and articulation were largely left to the ear’s intuition. “Penumbra” magnifies the shadow cast when one celestial body partially obscures the light from another. Moments from “Eclipses” are revisited through a telescopic lens, such that the small whole number relations hiding in the harmonies are magnified, into the field of rhythm. Small gestures orbit each other in wandering motion, building a web of cause and effect. The harmonic material from “Penumbra” is extracted from two chords occurring in measures 41-43 of “Eclipses.” The small whole number frequency ratios governing the cross-relations of these two chords are magnified and modified to create polyrhythms that cycle over several minutes.
20

Utvärdering av plattformar för tunga Java-klienter

Lindelöw, Björn January 2006 (has links)
<p>BRP Systems utvecklar och säljer affärssystem till mindre och medelstora tjänsteföretag. Huvudsystemet är en Java Swing-applikation och för att få bättre struktur på programmet önskar man vid utvecklingen använda ett lämpligt ramverk om något sådant går att identifiera. Denna rapport undersöker två sådana ramverk.</p><p>Ett ramverk kan användas som hjälp vid utvecklingen av komplexa applikationer. De fungerar som en grund till applikationen som utvecklas och kan erbjuda olika hjälpfunktioner som ofta behövs i vanliga program. Ramverk kan även få källkoden att bli mer strukturerad och lättunderhållen. Skriver man själv ett stort program från grunden är det lätt att programmet innehåller buggar och blir svårt att underhålla om man inte har tänkt igenom strukturen noga från början.</p><p>Två ramverk valdes ut som intressanta att utvärdera: Spring RCP och Eclipse RCP. Ramverken utvärderades utifrån fyra punkter; språkstöd, formulärhantering, menyhantering och actionhantering. Vid utvärderingen av ramverken implementerades dessa genom att skriva ett enklare program i respektive ramverk. Jag läste först in mig på Spring RCP för att se vad det erbjöd och implementerade sedan programmet i ramverket. Därefter gjorde jag likadant med Eclipse RCP.</p><p>Spring RCP visade sig vara det bättre ramverket på två av punkterna: språk- och formulärstödet. Vad gäller meny- och actionhantering hade ramverken ganska lika funktionalitet. Sammantaget var således Spring RCP bättre med utgång från dessa fyra punkter. Ytterligare aspekter som exempelvis dokumentation bör dock även beaktas innan man väljer ramverk.</p>

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