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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.
61

NUMERICAL SIMULATIONS OF ATMOSPHERIC DYNAMICS ON THE GIANT PLANETS

Lian, Yuan January 2009 (has links)
The giant planets exhibit banded zonal jet streams that have maintained theirstructures over decades. There are long-standing questions: how deep the windstructures extend? What mechanisms generate and maintain the observed winds?Why are the wind structures so stable? To answer these questions, we performedthree-dimensional numerical simulations of the atmospheric flow using the primitiveequations.First, we use a simple Newtonian cooling scheme as a crude approach to gener-ate atmospheric latitudinal temperature differences that could be caused by latentheating or radiation. Our Jupiter-like simulations show that shallow thermal forcingconfined to pressures near the cloud tops can produce deep zonal winds from thetropopause all the way down to the bottom of the simulated atmosphere (a fewhundred bars). These deep winds can attain speeds comparable to the zonal jetspeeds within the shallow, forced layer; they are pumped by Coriolis accelerationacting on a deep meridional circulation driven by the shallow-layer eddies.Next, we explicitly include the transport of water vapor and allow condensationand latent heating to occur whenever the water vapor is supersaturated. Our simu-lations show that large-scale moist convection associated with condensation of watervapor can produce multiple zonal jets similar to those on the gas giants (Jupiterand Saturn) and ice giants (Uranus and Neptune). For plausible water abundances(3-5 times solar on Jupiter/Saturn and 30 times solar on Uranus/Neptune), oursimulations produce about 20 zonal jets for Jupiter and Saturn and 3 zonal jetson Uranus and Neptune. Moreover, these Jupiter/Saturn cases produce equatorialsuperrotation whereas the Uranus/Neptune cases produce equatorial subrotation,consistent with the observed equatorial jet direction on these planets. Sensitiv-ity tests show that the water abundance is the controlling factor; modest waterabundances favor equatorial superrotation, whereas large water abundances favorequatorial subrotation. This provides a possible mechanism for the existence ofequatorial superrotation on Jupiter and Saturn and the lack of superrotation onUranus and Neptune.
62

Jobs-housing balance & individual spatial choices a case study of Saturn workers in Spring Hill, Tennessee /

Del Bosco, Jonathan, January 2006 (has links)
Thesis (M.S.) -- Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.
63

A Festa de Saturno: o Xênia e o Apoforeta de Marcial / The party of Saturn: Xenia and Apophoreta by Marcial

Alexandre Agnolon 13 September 2013 (has links)
Trataremos de dois livros de epigramas do poeta latino Marcial: Xênia e Apoforeta, dados a lume, respectivamente, nas Saturnais de 83 (ou 84) e 85 d.C. sob o principado de Domiciano. Nosso objetivo, em primeiro lugar, será discutir as características intensamente apotropaicas e propiciatórias tanto das Saturnais, como do próprio deus Saturno a despeito dos elementos lúgubres comumente a ele associados , para, em seguida, tentar demonstrar de que maneira a festividade romana interfere na fruição dos epigramas que compõem as referidas recolhas e exige que o poeta abandone, temporariamente, a comum acerbidade de seus versos. Tanto pelas Saturnais constituírem o princípio de unidade desses livros, como por Marcial buscar emular um conjunto de tratados antigos de natureza jocosa, populares durante os festejos consagrados a Saturno, acreditamos que o poeta legitima a existência de novo subgênero epigramático que é corolário das próprias Saturnais romanas. No final, apresentamos, como resultado de nossa investigação, tradução poética de Xênia e Apoforeta, inédita em língua portuguesa. / We will discuss two books of epigrams by the Latin poet Martial: Xenia and Apophoreta, published, respectively, in the Saturnalia of 83 (or 84) and 85 A.D. under the reign of Domitian. Our goal, in the first place, is to discuss the highly apotropaic and propitiatory features of both the Saturnalia, as the god Saturn itself despite the gloomy elements commonly associated with him. Then well try to demonstrate how the Roman festival interferes with the fruition of the epigrams in these collections, and demands that the poet abandons temporarily the common poignancy of his verses. Not only because Saturnalia constitute the principle of unity of these books, but because Martial seek to emulate a set of ancient treatises of facetious nature, popular during the festival dedicated to Saturn, we believe that the poet legitimate the existence of new epigrammatic subgenre which is corollary of the very Roman Saturnalia. Finally, we will present as a result of our investigation an original translation into Portuguese verse of Xenia and Apophoreta.
64

Alternative Mission Concepts for the Exploration of Outer Planets Using Small Satellite Swarms

Blocher, Andrew Gene 01 November 2017 (has links)
Interplanetary space exploration has thus far consisted of single, expensive spacecraft missions. Mission costs are particularly high on missions to the outer planets and while invaluable, finite budgets limit our ability to perform extensive and frequent investigations of the planets. Planetary systems such as Jupiter and Saturn provide extremely complex exploration environments with numerous targets of interest. Exploring these targets in addition to the main planet requires multiple fly-bys and long mission timelines. In LEO, CubeSats have changed the exploration paradigm, offering a fast and low cost alternative to traditional space vehicles. This new mission development philosophy has the potential to significantly change the economics of interplanetary exploration and a number of missions are being developed to utilize CubeSat class spacecraft beyond earth orbit (e.g., NEAScout, Lunar Ice Cube, Marco and BioSentinel). This paper takes the CubeSat philosophical approach one step further by investigating the potential for small satellite swarms to provide extensive studies of the Saturn system. To do this, an architecture was developed to best replicate the Cassini Primary Mission science objectives using swarms of CubeSats. Cassini was chosen because of its complexity and it defines a well-understood baseline to compare against. The paper outlines the overall mission architecture developed and provides a feasible initial design for the spacecraft in the architecture. The number of swarms needed, number of CubeSats per swarm, size of the CubeSats, overall science output and estimated mission cost are all presented. Additional science objectives beyond Cassini's capabilities are also proposed. Significant scientific returns can be achieved by the swarm based architecture and the risk tolerance afforded by the utilization of large numbers of low-cost sensor carriers. This study found a potential architecture that could reduce the cost of replicating Cassini by as much as 63%. The results of this investigation are not constrained to Saturn and can be easily translated to other targets such as Uranus, Neptune or the asteroid belt.
65

Plasma density characteristics of magnetic holes near the Kronian magnetosphere boundary surfaces

Bause, Marlon Luis January 2020 (has links)
Localized structures of the magnetic field strength depression are often observed in the interplanetarymedium, and they are called ‘magnetic holes’ after the original work of Turner et al. 1977. A numberof observations of similar features have been reported, while the mechanisms of their origin have notfully understood yet. The scale size of their structures varies from several to a few thousand of the protongyro radii, and their characteristic orientations of the magnetic field also vary, and therefore differenttypes of the magnetic holes have been suggested. To date, the magnetic holes are classified into Mirrormode and magnetic decreases (Tsurutani et al. 2011). Despite a large number of papers that report theobservational characteristics of the magnetic holes, many identify the feature using only the magneticfield data. This is due to the scale size of the structure at a large speed of the solar wind medium, thespatial resolution of the plasma instruments is often insufficient while the magnetic field instrument canusually obtain the data in high enough time resolution.The Cassini spacecraft orbited Saturn for almost 17 years and obtained a large amount of data in/near theKronian magnetosphere, where the series of the magnetic depletions have been also observed (Smith et al.1980). The Langmuir Probe (LP) onboard Cassini measures the spacecraft potential and, in turn, measuresthe electron density in in-situ in the outer magnetosphere and solar wind region. This measurement hasbeen done using the LP sweep mode which samples the current-voltage curve of the probe every 10 minin the outer magnetosphere. The LP has also been operated in the continuous mode that measures theprobe current at a fixed bias potential every 16 s allowing to calculate the electron density in a smallerscale that is required for the studies magnetic holes. However, there is no general calibration so far inorder to conduct a statistical study in the outer magnetosphere region. The goal of this project is toinvestigate the possibility to use the LP data for the magnetic hole study, calibrate the LP continuousmode to derive the plasma density near the magnetospheric of Saturn, and investigate the scale size of theplasma density structure in the magnetic holes, i. e. plasma β, the field strength and density.The calibration of the continuous data was done by finding a relation between the current at 11 V, whichis a typical bias voltage of continuous mode, and the spacecraft potential obtained by the LP the sweepmode data. Is is expected that the current at 11V is linearly proportional to the floating potential andtherefore can be used to derive the electron density with the potential and density relationship presentedby Morooka et al. 2009. I found that the spacecraft attitude against the sun has a strong effect on therelation, and derived 11V current-floating potential relationship depending on the different spacecraftattitude.Using the LP continuous data calibration above, I investigated the electron density characteristics aroundthe magnetic hold structure, and confirmed that they are generally in anticorrelation relationship. I estim-ated also the plasma β assuming a constant temperature of 100 eV and investigated their characteristicsfor the different types of magnetic holes (linear and rotational holes) both in the magnetosheath and theholes in the solar wind for the year 2011. For the Cassini dataset during 2011, various different shapeand sizes of magnetic hole events have been found. Most (80%) of the MHs appeared within a groupedstructure, while the rest (20%) are found as isolated type holes in the magnetosheath. Among the isolatedMHs, about 30% had "Gaussian shape" and about 40% had a substructure. The scale size for the electrondensity for the isolated holes were on average 50 s in the solar wind, and 75 s (the rotational holes) and120 s (the linear holes) in the magnetosheath. Therefore, I confirmed that the LP can obtain enough datapoints to resolve the magnetic holes structure in the magnetosheath. The Cassini LP data resolution isalso capable to resolve some of the magnetic hole structure in the solar wind.In summary, I confirmed that the Cassini LP continuous data calibrated in this study is capable toinvestigate the different types of magnetic hole structures. Using this calibrated electron data statisticallyfor the large number of Cassini orbit would helpful to further identify the MHs structures in the solar wind and the magnetosheath that can be a key to understand the generation mechanisms of the magneticholes. / Lokaliserade strukturer med låg magnetfältstyrkan ses ofta i interplanetära mediet och de kallas ’mag-netiska hål’ (MH) (Turner et al. 1977). Trots et antal observationer av sådana strukturer har observeratsär deras generationsmekanism ännu förstådd. Storleken av strukturerna varierar från ett fåtal till någratusen protongyroradier och även deras kännetecknande inriktningar i magnetfältet varierar. På grund avdetta har olika typer av MH förslagits. Idag klassificerar man MH som ’mirror mode’ och magnetiskaminskningar (Tsurutani et al. 2011). Många studier har undersökt de magnetiska hålens egenskaper,men tyvärr oftast baserats endast på magnetfältsdata. Detta kan bero på strukturernas storlek vid en storsolvindshastighet, där plasmainstrumenten oftast inte har tillräckligt hög tidsupplösning för mätningar,medan magnetfältsinstrumenten kan oftast tillhandahålla data i hög tidsupplösning.Cassini-rymdfarkosten kretsade runt Saturnus i nästan 17 år och erhöll stora mängder data i och näraSaturnus magnetosfär. Langmuir-sonden (LP) ombord Cassini mäter rymdfarkostens potential ochdärmed mäter den elektrontätheten i rymden. Instrumentet fungerar som en slags väderstation för rym-dplasma och möjliggör mätningen av fundamentala plasmaparametrar såsom elektrontäthet, jontäthet,elektrontemperatur och jonmassa i en tät plasmaområdet av nära Saturnus. I den yttre magnetosfären därden plasmatätheten är låg, kan LP mäta rymdfarkosts potential och plasmatätheten. Mätningen, så kallade’sweep mode’ kan skaffades var 10:e minuter. LP:en mäter också i ’kontinuerlig mode’ som möjligenkan mäta plasmatätheten i mer frekventa men den behöver allmän kalibrering. I detta projekt undersökerjag möjligheten att använda LP kontinuerlig data för att studera MH, skapa kalibraring funktion för’kontinuerlig mode’ för att uppskatta plasmatätheten i Saturnus magnetosfär, och även att undersökastorleken och karaktär av plasmatäthetenstrukturen i MH.Jag undersökte först relationen mellan LP ström vid 11V och rymdfarkostens potential i sweep mode data.De härledda funktionerna användes vidare för att uppskatta densiteten med användning av relationenmellan rymdfarkostens potential och elektrontätheten (Morooka et al. 2009). Jag upptäckte också attden kontinuerlig mode funktionen är olika beroende på LP sensors läge i förhållande till solen ochrymdfarkosten. Hur Cassini är inriktad har en stor effekt på relationen och därför beskriva jag fyra olikarelationer för olika inriktningsregioner. Med den kontinuerlig mode funktionen jag härlett, undersöktejag struktur av magnetiska hålen som har listats av Tomas Karlsson på KTH. År 2011 innehåller MH medmycket olika former och storlekar. Den mest (80%) MH identifierades som grupp och resten (20%) varsom isolerade MH i magnetosheath. Av dessa isolerande hål har ca. 30% en Gauss-form och nästan 40%av MH verkar ha en understruktur. Genom att jämföra magfältdatan med elektrontätheten bekräftadejag den allmänna antikorrelationen mellan magnetfältstyrkan och elektrontätheten i MH-strukturerna.Dessutom hittar jag en ökning av elektron β som beräknas med en temperatur av 100 eV för linjära ochroterade MH i den magnetosheath samt MH i solvinden under 2011. Storleken av de isolerade magnetiskahålen är i genomsnitt 50 s i solvinden, 75 s (roterade magnetiska hål) och 120 s (linjära magnetiska hålen)i magnetosheath:en. Därför kan Cassini LP ha tillräcklig många datapoäng för att upplösa struktur avMH i magnetosheath. I solvinden kan LP upplösa en del av relativt stora MH.Sammanfattningsvis kan LP:s kontinuerlig kalibreringen från detta projekt användas för att analyserade olika strukturerna och storlekar av MH. Med denna kalibrerade plasmatäthet data är det möjligt attidentifiera olika MH karaktär i statistiskt för det stora antalet Cassini data. Det skulle vara en stor hjälpför att förstå genereringsmekanismerna av de magnetiska hålen.
66

A Concept Study for Extraterrestrial Sea Exploration of Titan Via Deployable and Versatile Instrument Device (David) Buoys

Smith, Mary Kate 12 August 2016 (has links)
Saturn’s moon, Titan, has been a scientific marvel since Cassini’s flyby discovered methane-ethane lakes in the northern hemisphere. Several science missions to explore these lakes have been proposed, but none have been launched. Using these previous mission designs, as well as the success of the Huygens probe, this paper will discuss the development of a deployable multi-buoy system with the intent of studying the methane-ethane lakes. The buoys will study the chemical makeup of the lakes, determine meteorology of Titan atmosphere, and map the depth and floor of the targeted lakes. This thesis is a concept study on the multi-buoy system that reviews briefly the concept and design.
67

Computational Simulation Of Dynamics Of Nematic Liquid Crystals In The Presence Of Nanoparticles And Biological Macromolecules

Wu, Huangli 05 August 2006 (has links)
Recent research shows that liquid crystals can be used to report the presence of different types of substances through optical amplication of ligand-receptor binding. In this work, simulations based on a coarse-grained method have been performed to study a class of liquid-crystal-based sensors. A tensor order parameter was used to model the liquid crystalline system and the Beris-Edwards formulation was employed to obtain the time evolution of a liquid crystal medium containing particles. The simulation cases are built using three-dimensional unstructured meshes and the simulation geometries studied include simple models involving spheres as well as detailed modeling for a protein. The dynamics of a liquid crystal medium confined between two solid walls has been studied in the presence of spherical particles and a representative biological macromolecule. Comparisons of steady state and transient solutions from the present study with corresponding results from molecular dynamics based simulations in the literature yield good agreements.
68

Jobs-Housing Balance & Individual Spatial Choices: A Case Study of Saturn Workers in Spring Hill, Tennessee

Del Bosco, Jonathan 05 August 2006 (has links)
This study examines the jobs-housing balance and the excess commute of Saturn employees in Spring Hill. Until recently, the number of jobs has greatly exceeded the number of houses. In 2005 the balance is about even, however many newer residents are believed to be people who work in Nashville. Many Saturn employees live on the outskirts of Spring Hill and must commute longer distances to work. A spatial analysis using GIS of employee home locations shows that 74% of employees commute is in excess compared to if employees actually lived within Spring Hill. Surveys of Saturn employees shows traffic en route to work is a major frustration. It is suggested that future housing development in Spring Hill occur closer to Saturn. This will equilibrate the jobs-housing balance and will reduce the excess commute. Other Southern towns may wish to consider these results when planning for the development of automobile manufacturers.
69

TRANSLATION AND REPETITION: AN ARCHITECTURAL TRANSLATION OF W.G. SEBALD'S THE RING OF SATURN

LASH, DANIEL JAMES 02 July 2004 (has links)
No description available.
70

"My Music is Words" -- The Poetics of Sun Ra

Bowles, Nathaniel Earl 14 May 2008 (has links)
This thesis argues for a critical examination of the published writings of Le Sony'r Ra, also known as Sun Ra, a groundbreaking jazz musician and philosopher of the 20th century. Recent redistribution of Sun Ra's musical output, which includes hundreds of releases on many record labels from the 1950's onward, has prompted a critical renaissance towards his influence on jazz orchestration, band management, do-it-yourself ethics, and structured improvisation In spite of this resurgence of interest in his music, his written corpus has failed to produce a comparable level of criticism or discussion. It is my firm belief that it is the body of work's relative scarcity in print, not its value as literature, that has kept the material underground for such a lengthy period of time. With the recent republication of Sun Ra's daunting body of poetry and prose, the discovery of early manuscripts, and the surfacing of relevant critical essays, the time has come to analyze his poetic position within the context of African-American philosophical thought. / Master of Arts

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