Global ETD Search

11	Fluctuations quantiques et thermiques dans les transducteurs électromécaniques Grassia, Francesca 26 June 1998 (has links) (PDF) Les fluctuations sont présentes dans toute mesure et elles en limitent la sensibilité ultime. Ceci est vrai en particulier pour les fluctuations de nature fondamentale qui correspondent au bruit thermique et au bruit quantique. Un premier objectif de cette thèse a été le développement d'une méthode générale qui permette le traitement de ces fluctuations dans des systèmes de mesure comportant des éléments passifs et des éléments actifs remplissant des fonctions d'amplification ou de contre-réaction. Cette méthode, basée d'une part sur la théorie des réseaux, d'autre part sur le formalisme quantique de la matrice S, s'applique aux systèmes linéaires et, plus généralement, aux systèmes linéarisables autour du point de fonctionnement. Elle peut prendre en compte toutes les sources de bruit et décrit donc la non-idéalité de la mesure. Son caractère modulaire se prête bien au traitement des systèmes complexes. Un deuxième objectif a été l'étude des effets des fluctuations quantiques et thermiques sur la sensibilité des mesures électromécaniques. Le bruit dans ces systèmes, habituellement dominé par les fluctuations thermiques, s'est rapproché du niveau quantique, sous la pression des expériences nécessitant de très hautes sensibilités (détection des ondes gravitationnelles, test du principe d'équivalence dans l'espace) et grâce aux développements technologiques dans le domaine cryogénique. La méthode développée dans cette thèse fournit un cadre théorique consistent pour traiter fluctuations quantiques et thermiques dans ces systèmes. Des résultats précis ont été obtenus pour un accéléromètre conçu par l'ONERA pour des expériences de physique fondamentale dans l'espace et qui présente la particularité d'utiliser un mécanisme de friction froide. Ces résultats permettent d'estimer les limites ultimes de sensibilité d'un tel instrument. Fluctuations quantiques et thermiques Systèmes actifs Transducteurs électromécaniques Accéléromètres Friction froide Rétro-action Théorie des réseaux Mesure QND et BAE
12	Turkish-british Economic Relations 2002-2012: An Intensely Political Relationship Angliss, John 01 December 2012 (has links) (PDF) Over the last ten years Britain and Turkey have sustained an unusually harmonious economic relationship. However, this has not been the outcome of undirected free markets and the effective exploitation of comparative advantage. Instead, it has come about as the result of a series of political compromises. This analysis looks at how the relationship has evolved on a variety of political levels: through international organisations, state-to-state diplomacy, the direct state sponsorship of British business in Turkey and the varied political relations of British multinationals inside Turkey. At each level, activist British governments have used political methods to promote British business, even sometimes at the expense of their reputation or other strategic interests. Complementing this is a structural power imbalance between the two countries, which has helped open up Turkey&rsquo / s markets to British capital.
13	Theoretical analysis and simulation of microwave-generation from a coaxial vircator Hägg, Martin January 2017 (has links) High-power microwave, HPM, systems can be used as non-lethal weapons with the ability to destroy or disturb electronics, by damaging internal circuits and inducing high currents. Today microwave sources are being developed with peak powers exceeding 1 GW, one of these devices is the vircator, a narrowband source which is unique to the HPM community. In order to understand and develop microwave sources like the vircator it is necessary to have computer models, as simulations gives an invaluable understanding of the mechanisms involved during operation, saving time and development costs. This thesis presents the results from a theoretical analysis and a simulation study using a well known electromagnetic particle-in-cell code, Computer Simulation Technology Particle Studio. The results are then compared to measured data from a HPM system, the Bofors HPM Blackout. The results show that CST PS can be used to design and study the coaxial vircator with good results. HPM high power microwaves vircator virtual cathode oscillator cst particle-in-cell PIC particle studio microwave weapon HPM high power microwaves virtual cathode oscillator HPM mikrovågor strålvapen CST particle in cell BAE systems virkator strålkälla högeffekts mikrovågor koaxiell virkator
14	Analysis of noise levels, audio frequency and fuel consumption with propellers of type McCauley and MT on BAe Jetstream 32 / Analys av ljudnivå, ljudfrekvens samt bränslekonsumtion med propellrar av typerna McCauley och MT på en BAe Jetstream 3 Andersson, Magnus, Eriksson, Peter January 2012 (has links) This report describes a thesis project conducted at Direktflyg in Borlänge, in early 2012, where the aim was to analyse the difference in noise level, audio frequency and fuel consumption between propellers of the older type McCauley and the newer type MT on the aircraft type BAe Jetstream 32. To perform the analysis, the authors reviewed current procedures regarding noise certification from air safety agencies to be able to identify suitable methods for the noise level and audio frequency measurements. The results of the conducted noise level measurements show a general lower noise level throughout the cabin and a significant reduction in noise level behind row 2 when using the MT propeller compared to the McCauley type. In practice this means a lower perceived noise level for most passengers at an average passenger load factor. The frequency measurements show that the MT propeller generates audio frequencies which are perceived as lower in noise levels and are therefore more comfortable for passengers. The fuel consumption was also slightly lower when using the MT propeller compared to the McCauley type over the assigned time period and the determined limiting parameters. / Denna rapport beskriver ett examensarbete som genomfördes på Direktflyg i Borlänge under början av 2012, där syftet var att analysera skillnaden i ljudnivå, ljudfrekvens och bränslekonsumtion på flygplanstypen Jetstream 32 efter genomfört byte av propellrar från typen McCauley till typen MT på en av bolagets flygplansindivider. För att genomföra analysen har författarna granskat gällande procedurer angående ljudnivåmätning från styrande luftsäkerhetsorgan för att sedan kunna fastställa passande metoder för utförandet av ljudnivå- samt ljudfrekvensmätningar. Resultaten från ljudnivåmätningarna visar på en lägre ljudnivå över hela kabinen samt betydligt lägre ljudnivå bakom rad 2 vid användning av MT-propellrar jämfört med McCauley. I praktiken innebär detta en lägre upplevd ljudnivå för de flesta passagerare vid en genomsnittlig kabinfaktor. Frekvensmätningarna visar att MT-propellern genererar ljudfrekvenser som uppfattas som lägre i ljudnivå och därav också som behagligare för passagerarna. Bränslekonsumtionen var vidare något lägre vid användande av MT-propellrar jämfört med McCauley över den tidsperiod som innefattades inom arbetet och de begränsande parametrar som fastställdes. aeronautical aerospace engineering propeller jetstream direktflyg british aerospace MT McCauley frequency noise levels noise fuel consumption flyg flygteknik propeller McCauley MT jetstream Direktflyg ljudnivå frekvens ljudfrekvens bränsleförbrukning BAe british aerospace
15	Evaluation of the Hybrid-Electric Aircraft Project Airbus E-Fan X Benegas Jayme, Diego January 2019 (has links) (PDF) Purpose - This master thesis evaluates the hybrid-electric aircraft project E-Fan X with respect to its economical and environmental performance in comparison to its reference aircraft, the BAe 146-100. The E-Fan X is replacing one of the four jet engines of the reference aircraft by an electric motor and a fan. A turboshaft engine in the cargo compartment drives a generator to power the electric motor. --- Methodology - The evaluation of this project is based on standard aircraft design equations. Economics are based on Direct Operating Costs (DOC), which are calculated with the method of the Association of European Airlines (AEA) from 1989, inflated to 2019 values. Environmental impact is assessed based on local air quality (NOx, Ozone and Particulate Matter), climate impact (CO2, NOx, Aircraft-Induced Cloudiness known as AIC) and noise pollution estimated with fundamental acoustic equations. --- Findings - The battery on board the E-Fan X it is not necessary. In order to improve the proposed design, the battery was eliminated. Nevertheless, due to additional parts required in the new configuration, the aircraft is 902 kg heavier. The turboshaft engine saves only 59 kg of fuel. The additional mass has to be compensated by a payload reduced by 9 passengers. The DOC per seat-mile are up by more than 10% and equivalent CO2 per seat-mile are more than 16% up in the new aircraft. --- Research limitations - Results are limited in accuracy by the underlying standard aircraft design calculations. The results are also limited in accuracy by the lack of knowledge of some data of the project. --- Practical implications - The report contributes arguments to the discussion about electric flight. --- Social implications - Results show that unconditional praise given to the environmental characteristics of this industry project are not justified. ddc:620 info:eu-repo/classification/ddc/629.13 Luftfahrt Luftfahrzeug Elektroantrieb Flugmechanik Aeronautics Airplanes Electric propulsion Airplanes--Performance Betriebskosten Kraftstoffverbrauch Luftverschmutzung Fluglärm Projektbewertung Technikbewertung Luftfahrttechnik Flugtriebwerk Passagier Flugzeug Entwurf Dimensionierung Cost accounting Airplanes--Fuel consumption Environmental protection Airplanes--Noise Evaluation Technology assessment Aerospace engineering Airplanes--Jet propulsion Airplanes--Turbofan engines Design aircraft aircraft design flight mechanics engines certification DOC Direct Operating Costs Airbus E-Fan X BAe 146

Page generated in 0.0228 seconds