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Nomenclatura Unesco > (21) Astronomía y Astrofísica

Mostrando recursos 21 - 40 de 597

21. Numerical modelling of a parabolic trough solar collector - Hachicha, Ahmed Amine
Concentrated Solar Power (CSP) technologies are gaining increasing interest in electricity generation due to the good potential for scaling up renewable energy at the utility level. Parabolic trough solar collector (PTC) is economically the most proven and advanced of the various CSP technologies. The modelling of these devices is a key aspect in the improvement of their design and performances which can represent a considerable increase of the overall efficiency of solar power plants. In the subject of modelling and improving the performances of PTCs and their heat collector elements (HCEs), the thermal, optical and aerodynamic study of the fluid...

22. Contributions to ionospheric determination with global positioning system: solar flare detection and prediction of global maps of total electron content - García Rigo, Alberto
Two research studies have been addressed in this thesis. Both of them are of actual scientific interest and are based on processing GNSS data. The first part of this thesis is devoted to GNSS detection and monitoring of solar flares. The second one is devoted to GNSS prediction of ionospheric Total Electron Content. Regarding the first study, a new solar flare detector called SISTED has been designed and implemented. Its goal is to provide a simple and efficient way of detecting the most number of powerful X-class solar flares in real time operation. In addition, it can send early warning messages...

23. Microstructural characterization & viscoelastic properties of AlZnMg & AlCuMg alloys - Rojas Gregorio, José Ignacio
The comprehension of the viscoelastic behaviour of metals is of high interest as these materials are subjected to dynamic loads in most of their structural applications, and also because it enables a deeper understanding of several technologically essential properties, like mechanical damping and yielding. Thus, research on this field is needed not only because it may lead to new potential applications of metals, but also because predictability of the fatigue response may be greatly enhanced. Indeed, fatigue is the consequence of microstructural effects induced in a material under dynamic loading, while the viscoelastic behaviour is also intimately linked to the microstructure. Accordingly, the characterization of...

24. Precise GPS-based position, velocity and acceleration determination: algorithms and tools - Salazar Hernández, Dagoberto José
Esta tesis doctoral llevó a cabo el estudio, desarrollo e implementación de algoritmos para la navegación con sistemas globales de navegación por satélite (GNSS), enfocándose en la determinación precisa de la posición, velocidad y aceleración usando GPS, en modo post-procesado y lejos de estaciones de referencia. Uno de los objetivos era desarrollar herramientas en esta área y hacerlas disponibles a la comunidad GNSS. Por ello el desarrollo se hizo dentro del marco del proyecto preexistente de software libre llamado GPS Toolkit (GPSTk). Una de las primeras tareas realizadas fue la validación de las capacidades de la GPSTk para el procesado del pseudorango, realizando comparaciones con una...

25. Evolution formalisms of Einstein equations: Numerical and Geometrical Issues - Cordero Carrión, Isabel
The topic treated along this thesis is the theoretical and numerical study of formalisms of Einstein equations, with the final aim of applications to black holes and gravitational waves. The General Relativity theory of Einstein (1915) postulated that light and trajectories of all particles are curved by the geometry of spacetime. Schwarzschild a few months later and Kerr in 1963 found solutions which describe non-rotating and rotating black holes. From an astrophysical point of view, a stellar black hole can be seen as the final result of some kind of collapse of massive stars or merger of compact binaries objects. One...

26. Análisis de las anisotropías de la Radiación Cósmica del Fondo de Microondas mediante el uso de Filtros Adaptados - Herranz Muñoz, Diego
El estudio de las anisotropías de la Radiación Cósmica del Fondo de Microondas es una de las piedras de toque de la Cosmología actual. Una fase importante de dicho estudio consiste en el análisis previo de los datos mediante técnicas deprocesado estadístico que permiten identificar, separar y estudiar de forma independiente las diferentes componentes físicas que contribuyen a la emisión del cielo. En esta Tesis se propone una nueva técnica de filtrado, los Filtros Adaptados a la Escala, que permite detectar la emisión de fuentes compactas(galaxias y cúmulos de galaxias) de forma robusta atendiendo alas particularidades de su estructura espacial...

27. Calibration Validation and Polarimetry in 2D Aperture Synthesis. Application to MIRAS - Ribó i Vedrilla, Serni
La missió SMOS de l'Agència Europea de l'Espai (ESA) té com a objectiu mesurar la humitat del sòl i la salinitat dels oceans, paràmetres fonamentals per tal d'entendre el canvi climàtic global.MIRAS (Radiòmetre de microones generador d'imatges pel mètode de síntesi d'obertura) és un tipus d'instrument nou per a l'observació de la terra i és l'únic instrument de la missió SMOS. Consisteix en un agrupació aprimada (thinned array) en forma d'i grega amb 21 elements per braç. Amb aquesta tècnica s'aconsegueixen grans obertures sintètiques amb una massa relativament reduida.Aquesta nova tecnologia ha estat triada per a la missió SMOS, per...

28. Testing the initial-final mass relationship of white dwarfs - Catalán Ruiz, Sílvia
White dwarfs are the final remnants of low- and intermediate-mass stars. About 95% of main- sequence stars will end their evolutionary pathways as white dwarfs and, hence, the study of the white dwarf population provides details about the late stages of the life of the vast majority of stars.Since white dwarfs are long-lived objects, they also constitute useful objects to study the structure and evolution of our Galaxy. For instance, the initial-final mass relationship, which connects the final mass of a white dwarf with the initial mass of its main-sequence progenitor, is of paramount importance for different aspects in modern...

29. Payload data handling, telemetry and data compression systems for Gaia. - Portell i de Mora, Jordi
Gaia, la nova missió astromètrica de la ESA amb un llançament previst pel 2011, observarà més de mil milions d'estels i altres objectes amb una exactitud sense precedents. Els seus ambiciosos objectius desbanquen completament les missions rivals d'altres agències. Al final de la seva vida útil es generarà el major i més complert mapa tridimensional de la nostra Galàxia.Una missió com aquesta suposa grans esforços tecnològics i de disseny ja que caldrà detectar, seleccionar i mesurar centenars d'estels cada segon, per enviar-ne posteriorment les dades cap a la Terra -a més d'un milió i mig de quilòmetres. Hem centrat el...

30. Modelling And Analysis Of Crack Turning On Aeronautical Structures - Llopart Prieto, Llorenç
La motivació de la tesis deriva en el interès de la indústria aeronàutica a explotar, per mitjà d'un disseny adaptat, la utilització del gir d'esquerda per protegir els reforços situats davant una esquerda que s'està propagant en la xapa d'una estructura integral. L'objectiu principal és l'avaluació i predicció del gir d'esquerda en situacions de càrrega pròximes a Mode I, proporcionant una eina de modelització i un criteri confident. L'entorn industrial sota el qual s'ha realitzat aquest treball requereix una predicció ràpida del comportament estructural proporcionant informació útil als constructors. Per aquest motiu la predicció del gir d'esquerda s'ha investigat utilitzant...

31. Contributions to the Optimisation of aircraft noise abatement procedures - Prats Menéndez, Xavier
Tot i que en les últimes dècades la reducció del soroll emès pels avions ha estat substancial, el seu impacte a la població ubicada a prop dels aeroports és un problema que encara persisteix. Contenir el soroll generat per les operacions d'aeronaus, tot assumint al mateix temps la creixent demanda de vols, és un dels principals desafiaments a que s'enfronten les autoritats aeroportuàries, els proveïdors de serveis per a la navegació aèria i els operadors de les aeronaus. A part de millorar l'aerodinàmica o les emissions sonores de les aeronaus, l'impacte acústic de les seves operacions es pot reduir també...

32. Algorithms and Methods for Robust Geodetic kinematic Positioning - Talaya López, Julià
El sistema NAVSTAR/GPS ha desenvolupat un paper molt important en les tècniques de posicionament cinemàtic geodèsiques, especialment en la determinació de la trajectòries per a la orientació de sensors aerotransportats d'observació de la terra. Amb l'excepció dels sensors fotogramètrics tradicionals la orientació dels sensors moderns aerotransportats depenen completament del posicionament GPS o bé de la integració GPS/INS. Per tant el posicionament GPS ha de ser precís i sobre tot fiable. Aquesta tesis es basa en l'estudi de nous algorismes i configuracions de missions que permetin augmentar el nivells de robustesa i fiabilitat en la determinació de trajectòries cinemàtiques aèries. Des...

33. Searches for point-like and extended neutrino sources close to the galactic center using the antares neutrino telescope - Adrian Martinez, Silvia; Albert, Andreas; André, Michel
A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates R.A. =-46.°8 and decl. =-64.°9 and corresponds to a 2.2s background fluctuation. In addition, upper limits on the flux normalization of an E -2 muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of seven events relatively close to the Galactic Center...

34. Searches for point-like and extended neutrino sources close to the galactic center using the antares neutrino telescope - Adrian Martinez, Silvia; Albert, Andreas; André, Michel
A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates R.A. =-46.°8 and decl. =-64.°9 and corresponds to a 2.2s background fluctuation. In addition, upper limits on the flux normalization of an E -2 muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of seven events relatively close to the Galactic Center...

35. Searches for point-like and extended neutrino sources close to the galactic center using the antares neutrino telescope - Adrian Martinez, Silvia; Albert, Andreas; André, Michel
A search for cosmic neutrino sources using six years of data collected by the ANTARES neutrino telescope has been performed. Clusters of muon neutrinos over the expected atmospheric background have been looked for. No clear signal has been found. The most signal-like accumulation of events is located at equatorial coordinates R.A. =-46.°8 and decl. =-64.°9 and corresponds to a 2.2s background fluctuation. In addition, upper limits on the flux normalization of an E -2 muon neutrino energy spectrum have been set for 50 pre-selected astrophysical objects. Finally, motivated by an accumulation of seven events relatively close to the Galactic Center...

36. Dark energy and thermonuclear supernovae - Domínguez, I; Bravo Guil, Eduardo; Piersanti, L; Tornambé, A; Straniero, O; Höfflich, P
Nowadays it is widely accepted that the current Universe is dominated by dark energy and exotic matter, the so called StandardModel of Cosmoloy or _CDM model. All the available data (Thermonuclear Supernovae, Cosmic Microwave Background, Baryon Acoustic Oscillations, Large Scale Structure, etc.) are compatible with a flat Universe made by _70% of dark energy. Up to now observations agree that dark energy may be the vacuum energy (or cosmological constant) although improvements are needed to constrain further its equation of state. In this context, the còsmic destiny of the Universe is no longer linked to its geometry but to the...

37. Dark energy and thermonuclear supernovae - Domínguez, I; Bravo Guil, Eduardo; Piersanti, L; Tornambé, A; Straniero, O; Höfflich, P
Nowadays it is widely accepted that the current Universe is dominated by dark energy and exotic matter, the so called StandardModel of Cosmoloy or _CDM model. All the available data (Thermonuclear Supernovae, Cosmic Microwave Background, Baryon Acoustic Oscillations, Large Scale Structure, etc.) are compatible with a flat Universe made by _70% of dark energy. Up to now observations agree that dark energy may be the vacuum energy (or cosmological constant) although improvements are needed to constrain further its equation of state. In this context, the còsmic destiny of the Universe is no longer linked to its geometry but to the...

38. Simulations of radiative shocks and jet formation in laboratory plasmas - Velarde, Pedro; González, Matthias; Oliva, Eduardo; Kasperczuk, Andrzej; Pisarczyk, Tadeusz; Ullschmied, Jiri; Stehlé, Chantal; Rus, Bedrich; García Senz, Domingo; Bravo Guil, Eduardo; Relaño, Antonio
We present the simulations of two relevant hydrodynamical problems related to astrophysical phenomena performed by three different codes. The numerical results from these codes will be compared in order to test both the numerical method implemented inside them and the influence of the physical phenomena simulated by the codes. Under some conditions laser produced plasmas could be scaled to the typical conditions prevailing in astrophysical plasmas. Therefore, such similarity allows to use existing laser facilities and numerical codes suitable to a laser plasma regime, for studying astrophysical proccesses. The codes are the radiation fluid dynamic 2D ARWEN code and the...

39. Diseño, construcción y uso de una cámara CCD para observaciones astronómicas - Roca Molina, Felipe
En este proyecto se presenta la construcción de una cámara CCD (dispositivo de cargaacoplada) para su uso posterior en aplicaciones astronómicas siguiendo y adaptando lasindicaciones del texto The CCD Camera Cookbook (Berry et al., 1994). Se explica elfuncionamiento de una cámara CCD a nivel sencillo particularizada para el chip TC211de la casa Texas Instuments.Se ha diseñado y construido las placas necesarias y se ha realizado un amplio estudiodel funcionamiento de la circuitería (preamplificador, convertidor A/D) y la lógica delchip TC211. Se ha hecho una breve explicación de la célula peltier (no desarrollada enel presente proyecto pero objeto de futuras ampliaciones)...

40. Simulations of radiative shocks and jet formation in laboratory plasmas - Velarde, Pedro; González, Matthias; Oliva, Eduardo; Kasperczuk, Andrzej; Pisarczyk, Tadeusz; Ullschmied, Jiri; Stehlé, Chantal; Rus, Bedrich; García Senz, Domingo; Bravo Guil, Eduardo; Relaño, Antonio
We present the simulations of two relevant hydrodynamical problems related to astrophysical phenomena performed by three different codes. The numerical results from these codes will be compared in order to test both the numerical method implemented inside them and the influence of the physical phenomena simulated by the codes. Under some conditions laser produced plasmas could be scaled to the typical conditions prevailing in astrophysical plasmas. Therefore, such similarity allows to use existing laser facilities and numerical codes suitable to a laser plasma regime, for studying astrophysical proccesses. The codes are the radiation fluid dynamic 2D ARWEN code and the...

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