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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

Turboelectric Distributed Propulsion System Modelling

Liu, Chengyuan 12 1900 (has links)
The Blended-Wing-Body is a conceptual aircraft design with rear-mounted, over wing engines. Turboelectric distributed propulsion system with boundary layer ingestion has been considered for this aircraft. It uses electricity to transmit power from the core turbine to the fans, therefore dramatically increases bypass ratio to reduce fuel consumption and noise. This dissertation presents methods on designing the TeDP system, evaluating effects of boundary layer ingestion, modelling engine performances, and estimating weights of the electric components. The method is first applied to model a turboshaft-driven TeDP system, which produces thrust only by the propulsors array. Results show that by distributing an array of propulsors that ingest a relatively large mass flow directly produces an 8% fuel burn saving relative to the commercial N+2 aircraft (such as the SAX-40 airplane). Ingesting boundary layer achieves a 7-8% fuel saving with a well-designed intake duct and the improved inlet flow control technologies. However, the value is sensitive to the duct losses and fan inlet distortion. Poor inlet performance can offset or even overwhelm this potential advantage. The total weight of the electric system would be around 5,000-7,000 kg. The large mass penalties further diminish benefits of the superconducting distributed propulsion system. The method is then applied to model a turbofan-driven TeDP system, which produces thrust by both the propulsors array and the core-engines. Results show that splitting the thrust between propulsors and core-engines could have a beneficial effect in fuel savings, when installation effects are neglected. The optimised thrust splitting ratio is between 60-90%, the final value depends on the propulsor intake pressure losses and the TeDP system bypass ratio. Moreover, splitting the thrust can reduce the weight of the electric system with the penalty of the increased core-engine weight. In short, if the power density of the superconducting system were high enough, turboshaft-driven TeDP would be preferable to power the N3-X aircraft
62

Structural Reconnaissance Mapping of the Nasa Basement Window, Southern Norrbotten Caledonides

Hedin Baastrup, Hugo January 2018 (has links)
Too few documentative descriptions exist from the reactivated Proterozoic Nasa Basement window in Sweden. This re-exposed crustal piece predominantly consisting of 1.8 Ga granite and volcanic basement rock lack structural evidences on maps. The Western Gneiss region gave example of how rocks in extreme cases may experience protolith overprinting through collisional vertical granite basement subduction to eclogite ambient conditions, which would give traces in metamorphic quartz (coesite), muscovite, pyroxene and kyanite, and increased densities. Preliminary indications from literature points towards a locally passive Nasa Basement with limited translation, but because of too little documentation it cannot be assured metamorphic inertia under fluid absence has been unimportant in the basement evolution. To address this highly structural issue, field reconnaissance mapping and sampling was carried out, and aimed to achieve a structural characterisation of historic deformation back to Proterozoic time. Observations were collected from 166 outcrop vicinities, and 17 of 27 carefully examined thin sections aimed to describe microscopic structures, in addition to mineral relation to metamorphic minerals. Collected evidences in this project encompass a Proterozoic macroscopic concentric fold with axis striking NW-SE, as well as, mesoscopic folds striking WNW-ESE. Tectonic movements record syn-collisional top-SE and post- collisional top-SW translation, which truncate weakly shortened and foliated blocks. Basement blocks locally preserve igneous coarse but weakly recrystallized texture fabrics. Overall optically produced paleothermometry indicates low- to medium grade facies conditions of deformation, through widespread bulging recrystallization, occasional subgrain rotation and rare grain boundary migration in quartz. Feldspar response to deformation is brittle and rarely ductile. Hydrous biotite, chlorite and epidote are abundant. Mineralogy together with an observed average density of 2,6 g/cm3 can possibly reject the idea of unreacted local continental subduction to eclogite depths, due to the overall presence of hydrous mineral phases. Top-to-the shear sense proves Caledonian reactivation, but Bourguer anomaly indicates at least locally an important limited translation. NW-SE striking lineaments and strikes of foliation show best accordance with lineaments mapped in Norway and alignment with tectonic contacts in the Baltica interior, and do so show the best examples of candidates for Proterozoic structures.
63

Análise ergonômica do trabalho do controle de aproximação aérea (APP) em situação real

Vargas, Cleyton Vieira de January 2007 (has links)
Esta pesquisa analisou o trabalho dos controladores de tráfego aéreo em diferentes cenários reais, no controle de Aproximação (APP) de tráfego aéreo de Porto Alegre (APP PA). Com base em entrevistas, questionário e filmagens de cenas reais, foram analisadas as percepções de 14 controladores quanto às demandas da profissão; quanto aos fatores cognitivos (conhecimento, estratégia, dinâmica atencional) utilizados para o desempenho da atividade; e quanto à carga de trabalho com base no questionário adaptado do NASA TLX. Os resultados mostram que, entre outras variáveis, a complexidade da tarefa depende das condições meteorológicas, do número e tipo de aeronovaves em observação, sendo que os controladores percebem as cenas de forma semelhante, independente do tempo de profissão e de controle no APP PA. Os controladores tomam as decisões de forma coordenada, sendo que a condução de um tráfego aéreo seguro depende da coordenação bem executada. / This research analyzed the job of the air traffic controllers in different real scenes, at the Terminal Radar Approach Control (TRACON) of the air traffic in Porto Alegre (TRACON PA). Based on interviews, a questionnaire and shootings of real scenes, the perception of 14 controllers were analysed in relation to the demands of their job, in relation to the cognitive factors (knowledge, strategy, attencional dynamic) used for the performance of the activity; and related to the workload based on the adapted questionnaire of NASA TLX. The results show that, among other varieties, the complexity of the task depends on the meteorological conditions and on the number and type of aircrafts observed. The controllers understand the scenes in a similar way, not related on how much time they have working on the job nor working controlling time at TRACON PA. The controllers take the decisions in a coordinated way, because the conduction of the safe air traffic depends on a well done coordination.
64

Análise ergonômica do trabalho do controle de aproximação aérea (APP) em situação real

Vargas, Cleyton Vieira de January 2007 (has links)
Esta pesquisa analisou o trabalho dos controladores de tráfego aéreo em diferentes cenários reais, no controle de Aproximação (APP) de tráfego aéreo de Porto Alegre (APP PA). Com base em entrevistas, questionário e filmagens de cenas reais, foram analisadas as percepções de 14 controladores quanto às demandas da profissão; quanto aos fatores cognitivos (conhecimento, estratégia, dinâmica atencional) utilizados para o desempenho da atividade; e quanto à carga de trabalho com base no questionário adaptado do NASA TLX. Os resultados mostram que, entre outras variáveis, a complexidade da tarefa depende das condições meteorológicas, do número e tipo de aeronovaves em observação, sendo que os controladores percebem as cenas de forma semelhante, independente do tempo de profissão e de controle no APP PA. Os controladores tomam as decisões de forma coordenada, sendo que a condução de um tráfego aéreo seguro depende da coordenação bem executada. / This research analyzed the job of the air traffic controllers in different real scenes, at the Terminal Radar Approach Control (TRACON) of the air traffic in Porto Alegre (TRACON PA). Based on interviews, a questionnaire and shootings of real scenes, the perception of 14 controllers were analysed in relation to the demands of their job, in relation to the cognitive factors (knowledge, strategy, attencional dynamic) used for the performance of the activity; and related to the workload based on the adapted questionnaire of NASA TLX. The results show that, among other varieties, the complexity of the task depends on the meteorological conditions and on the number and type of aircrafts observed. The controllers understand the scenes in a similar way, not related on how much time they have working on the job nor working controlling time at TRACON PA. The controllers take the decisions in a coordinated way, because the conduction of the safe air traffic depends on a well done coordination.
65

Geografický, historický a ekonomický rozvoj amerického státu Florida / The Geographical, Historical and Economic Development of the State of Florida, U.S.A.

BARTUŠKOVÁ, Lucie January 2010 (has links)
Abstract The first part of the thesis would concentrate on the general characteristics of the state of Florida, namely on its geographical, social, cultural and economic features. In the second part she will analyze some historical aspects of the colonization of the American south-east and she would concentrate on contemporary politics of Cuban immigration. This chapter is supplemented with the results of the testimonies made by people living in Florida. Another part would be devoted to the Kennedy Space Center and its contemporary research. The final part of the thesis processes the data obtained in the survey which was made in some secondary schools in České Budějovice. The purpose of the survey is to verify how much the students of secondary schools know about Florida.
66

Análise ergonômica do trabalho do controle de aproximação aérea (APP) em situação real

Vargas, Cleyton Vieira de January 2007 (has links)
Esta pesquisa analisou o trabalho dos controladores de tráfego aéreo em diferentes cenários reais, no controle de Aproximação (APP) de tráfego aéreo de Porto Alegre (APP PA). Com base em entrevistas, questionário e filmagens de cenas reais, foram analisadas as percepções de 14 controladores quanto às demandas da profissão; quanto aos fatores cognitivos (conhecimento, estratégia, dinâmica atencional) utilizados para o desempenho da atividade; e quanto à carga de trabalho com base no questionário adaptado do NASA TLX. Os resultados mostram que, entre outras variáveis, a complexidade da tarefa depende das condições meteorológicas, do número e tipo de aeronovaves em observação, sendo que os controladores percebem as cenas de forma semelhante, independente do tempo de profissão e de controle no APP PA. Os controladores tomam as decisões de forma coordenada, sendo que a condução de um tráfego aéreo seguro depende da coordenação bem executada. / This research analyzed the job of the air traffic controllers in different real scenes, at the Terminal Radar Approach Control (TRACON) of the air traffic in Porto Alegre (TRACON PA). Based on interviews, a questionnaire and shootings of real scenes, the perception of 14 controllers were analysed in relation to the demands of their job, in relation to the cognitive factors (knowledge, strategy, attencional dynamic) used for the performance of the activity; and related to the workload based on the adapted questionnaire of NASA TLX. The results show that, among other varieties, the complexity of the task depends on the meteorological conditions and on the number and type of aircrafts observed. The controllers understand the scenes in a similar way, not related on how much time they have working on the job nor working controlling time at TRACON PA. The controllers take the decisions in a coordinated way, because the conduction of the safe air traffic depends on a well done coordination.
67

Newspaper Coverage of Mars in the United States and the United Kingdom 2011-2016

Mace, Mikayla M., Mace, Mikayla M. January 2017 (has links)
The news media have documented the missions of the National Aeronautics and Space Administration (NASA) since its formation in 1958. Little of that coverage, however, has focused on Mars exploration and colonization, which has only recently become a serious target of interest for NASA. The current study examines how three elite print newspapers in the United States and three in the United Kingdom framed Mars coverage between 2011 and 2016. A content analysis found that most of the frames were similar to those observed in previous studies, such as exploration, scientific knowledge, business, nationalism, settlement, legacy, and fear. New frames, including life, health, social justice, and social engagement, emerged from the current study. The framing and tone of Mars articles were deployed similarly in U.S. and U.K. newspapers despite the different objectives of each country's space program. From the Apollo moon shots to human exploration of Mars, each successive era of spaceflight has been framed in a logical progression from concept to completion that resonates with the values of the times.
68

Att upprätthålla och stärka legitimitet – En analys av NASA:s visuella kommunikation

Viktor, Ekblom January 2020 (has links)
Uppsatsens syfte är att undersöka och utveckla förståelse för hur USA:s civila rymdmyndighet NASA:s grafiska kommunikation bidrar till att stärka och bibehålla dess legitimitet. Detta analyseras utifrån ett visuellt material bestående av fem utvalda bilder som publicerats av NASA i olika typer av medier. Analysen sker i två steg, först genom en semiotisk bildanalys som sedan utvecklas vidare i en kritisk diskursanalys. Resultatet visar på likheter mellan de olika medierna i det visuella materialet som syftar till att stärka centrala teman i NASA:s kommunikation. Det högteknologiska och vetenskapliga, människan och mångfald samt möjligheter och optimism är alla teman som används på olika sätt och syftar till att bibehålla och stärka NASA:s legitimitet och handlingsfrihet. Resultatet tas slutligen upp i en diskussion, där det grafiska, det politiska och det historiska kopplas samman.
69

Qualitative Methods Used to Develop and Characterize the Circulation Control System on Cal Poly's AMELIA

Paciano, Eric N 01 September 2013 (has links)
The circulation control system onboard Cal Poly's Advanced Model for Extreme Lift and Improved Aeroacoustics was a critical component of a highly complex wind tunnel model produced in order to fulfill the requirements of a NASA Research Announcement awarded to David Marshall of the Aerospace Engineering Department. The model was based on a next generation, 150 passenger, regional, cruise efficient, short take-off and landing concept aircraft that achieved high lift through circulation control wings and over-the-wing mounted engines. The wind tunnel model was 10-ft in span, used turbine propulsion simulators, and had a functioning circulation control system driven from tunnel supplied high pressure air. Wind tunnel test results will be compiled into an open-source database intended for validation of predictive tools whose purpose is to advance the state- of-the-art in predictive capabilities for the next generation aircraft configurations. The model's circulation control system produced highly directional, nonuniform flow, and required significant modification in order to generate flow suitable for representation in predictive software. The effort and methods used to generate uniform flow along the circulation control slots is detailed herein. Additionally the results of the system characterization are presented and include a thorough analysis of the slot height, the wing symmetry, and total pressure at the circulation control jet exit. These datasets are intended to aid in making adjustments to the simulation such that it accurately reflects the condition at which the model was tested. Many flow visualization results from the wind tunnel test are also presented to serve as a medium of comparison for results from predictive tools. Oil flow visualization was conducted at many test conditions and provides insight to AMELIA's surface flow in blown and unblown regions. Of particular interest were streamlines at the wingblend, which exhibited some outboard turning, and streamlines on the lower surface where the leading edge stagnation point was investigated. Smoke flow visualization was also utilized to explore the flowfield. The deflection of a individual streamline, under the influence of a changing discharge coefficient as investigated along with the discharge coefficients effect on the extended flowfield. Collectively, the images depict the massive augmentation of the flowfield caused by the presence of the circulation control wing.
70

Proteomic Analysis of Arabidopsis Seedlings Germinated in Microgravity to Identify Candidate Genes for Gravity Signal Transduction

Basu, Proma 20 September 2019 (has links)
No description available.

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