Finalized PhD theses

Number of entries: 82

The Friedmann cosmological models in dilatation and modified gravity and account of quantum effects.

Status: defended (26/02/2006)
Student: Yu.Shaido
Supervised by: Sergei D Odintsov
University: Tomsk State Pedagogical University

The study of Friedmann universe in modified gravity with account of quantum effects is presented. The conformal anomaly effects are taken into account. The new model of dark energy as modified gravity with ideal fluid described by equation of state with bulk viscosity is suggested. The scalar-tensor…
Status: defended (26/02/2006)
Student: Yu.Shaido
Supervised by: Sergei D Odintsov
University: Tomsk State Pedagogical University

The study of Friedmann universe in modified gravity with account of quantum effects is presented. The conformal anomaly effects are taken into account. The new model of dark energy as modified gravity with ideal fluid described by equation of state with bulk viscosity is suggested. The scalar-tensor friedmann cosmology is investigated.

Calibration, Validation and Polarimetry in 2D Aperture Synthesis: Application to MIRAS

Status: defended (30/06/2005)
Student: Serni Ribó
Supervised by: Martín-Neira, M.; Torres, F.
University: Universitat Politècnica de Catalunya

The SMOS mission of the European Space Agency (scheduled 2007) is devoted to measure Soil Moisture and Ocean Salinity, which are key parameters on the understanding of global climate change. The single instrument of this mission is the MIRAS (Microwave Imaging Radiometer using Aperture Synthesis), a…
Status: defended (30/06/2005)
Student: Serni Ribó
Supervised by: Martín-Neira, M.; Torres, F.
University: Universitat Politècnica de Catalunya

The SMOS mission of the European Space Agency (scheduled 2007) is devoted to measure Soil Moisture and Ocean Salinity, which are key parameters on the understanding of global climate change. The single instrument of this mission is the MIRAS (Microwave Imaging Radiometer using Aperture Synthesis), a new kind of instrument devoted to Earth observation. It is a thinned Y-shaped array with 21 elements per arm. With this technique a large synthetic aperture antenna with relative low weight can be obtained. This novel technique has been selected for the SMOS mission in order to fulfil both criteria ground resolution (35-50km) and revisit time (3 days). Similar instruments to MIRAS have already been used for radio astronomy but in that case only sources with a narrow angular size (stars and galaxies) were observed. In the case of MIRAS, the Earth is an extended source of thermal radiation, which almost fills up the complete field of view of MIRAS. The consequence of it is that the calibration techniques developed for radio astronomy may not be used in the SMOS mission. This thesis is mainly focused to experimentally test several calibration techniques and to prove the imaging properties of MIRAS. A second part is devoted to the polarimetric mode of MIRAS and its capability to improve its performance. This thesis was started thanks to a two year grant (from summer 2000 to summer 2002) at the ESTEC centre of the European Space Agency in the Netherlands. During this time the first experimental campaigns aimed to test calibration methods and imaging capabilities of MIRAS were done. In these so called image validation tests a first MIRAS prototype was used. The planning, preparation, execution and data processing for different tests was done. The capability of the calibration methods was demonstrated, showing also in which direction further research should be undertaken in order to refine them. The imaging properties of MIRAS were also demonstrated with the measurement of its impulsional response. The most important results are presented here. At the ESTEC centre theoretical work and simulations on polarimetric interferometry have also been done. This research contributed to the formulation of the polarimetric visibility function and the definition of the polarimetric operation mode of MIRAS. After the two years stage at ESTEC, the thesis was continued at the Laboratory of Space Technology (LST) of the Helsinki University of Technology (HUT) for three months (August 2002 to October 2002), as an invited researcher. There the HUT-2D interferometric radiometer, an airborne demonstrator instrument for MIRAS, was being constructed. The experience gained in the previous campaigns was shared with the HUT-2D team and the calibration methods were tested in a different instrument, confirming the previous results. In February 2003 this thesis was continued at the Institut d'Estudis Espacials de Catalunya (IEEC) under a research contract of the Spanish ministry of research. There the effect of Faraday rotation on MIRAS was studied. A solution for compensating it was proposed, making use of the polarimteric operation mode of MIRAS. The thesis was continued at IEEC, designing and manufacturing the Electrical Ground Support Equipment (EGSE) of an airborne demonstrator of MIRAS, known as SAM (Small Airborne MIRAS). This work was done for ESA. This instrument implements the complete calibration scheme with two-level noise injection, which is arefinement of the calibration schemes used in previous MIRAS prototypes. Preliminary experimental results of this novel calibration technique are also presented in this thesis.

X-ray emission from classical novae

Status: defended (22/09/2004)
Student: Sala, G.
Supervised by: Margarita Hernanz Carbó
University: Universitat de Barcelona

To be included shortly
Status: defended (22/09/2004)
Student: Sala, G.
Supervised by: Margarita Hernanz Carbó
University: Universitat de Barcelona

To be included shortly

The formation of large scale structures in the Universe: new hints from the power spectrum and the three-point correlation function

Status: defended (26/06/2002)
Student: Barriga Carrasco, Jose
Supervised by: Enrique Gaztañaga

The formation of large scale structures in the Universe: new hints from the power spectrum and the three-point correlation function. We present a new algorithm to compare the 3-point correlation function in theory and in N-body simulations. We also present a comparison of the power spectrum as measure…
Status: defended (26/06/2002)
Student: Barriga Carrasco, Jose
Supervised by: Enrique Gaztañaga

The formation of large scale structures in the Universe: new hints from the power spectrum and the three-point correlation function. We present a new algorithm to compare the 3-point correlation function in theory and in N-body simulations. We also present a comparison of the power spectrum as measure by CMB and galaxy observations to test the the ci

Gravitational lensing with relativistic objects

Status: defended (27/05/2002)
Student: Ernesto Eiroa
Supervised by: Diego F. Torres ; Romero, G.
University: Universidad Nacional de Buenos Aires, Argentina

See the full record in the link below (from Fermilab library)
Status: defended (27/05/2002)
Student: Ernesto Eiroa
Supervised by: Diego F. Torres ; Romero, G.
University: Universidad Nacional de Buenos Aires, Argentina

See the full record in the link below (from Fermilab library)

Sea Surface Determination Using GNSS Reflected Signals

Status: defended (08/03/2002)
Student: Estel Cardellach Galí
Supervised by: Antonio Rius Jordán
University: Universitat Politècnica de Catalunya

The Global Navigation Satellite Systems (GNSS) are large, stable and calibrated sets of spaceborne L-band microwave transmitters with very well characterized properties. They provide global and permanent coverage as required by the meteorological, oceanographical and climate scientist. All these features…
Status: defended (08/03/2002)
Student: Estel Cardellach Galí
Supervised by: Antonio Rius Jordán
University: Universitat Politècnica de Catalunya

The Global Navigation Satellite Systems (GNSS) are large, stable and calibrated sets of spaceborne L-band microwave transmitters with very well characterized properties. They provide global and permanent coverage as required by the meteorological, oceanographical and climate scientist. All these features make the GNSS signal an appropriate candidate to be an excellent source of opportunity for bistatic monitoring of the Oceans' surface.

The dissertation 'Sea Surface Determination Using GNSS Reflected Signals' tackles the question of how the GNSS signal scattered off the ocean surface can be used to obtain geophysical information about the sea-air interface. The focus is put on the retrieval of the surface roughness and/or the wind.

The thesis defends a scatterometric approach where the distribution of the scattered power crosswise the illuminated area is used to infer the roughness of the surface. The distribution or mapping is achieved by parceling the sea area in cells whose scattered signal has different delay and frequency properties. This information is gathered in anobservable called waveform.

The structure of the thesis has been divided in three main parts: (a) the modeling of the scattered GNSS signal (GNSSr); (b) the feasibility study; and (c) the experimental validation.

The scatterometric GNSSr forward and backward models are presented. The former generates the waveform of the reflected signal as a function of the geometry of the scattering, instrumental parameters, as well as the roughness of the sea surface. The backward approach proposed at this level tries to infer the sea surface roughness characteristics of the illuminated area through the inversion of the waveform.

The expected performance of the scatterometric-GNSSr system is analyzed as a first order examination of its capabilities in terms of resolution and accuracy of the wind measurements. The aim of this part of the study is to determine how precisely can the wind be measured by the GPSr techniques proposed in the backward model, as wellas how can these observations cover the Oceans.

Col·lisions d'objectes compactes amb SPH

Status: defended (05/12/2001)
Student: Josep Guerrero
Supervised by: Jordi Isern Vilaboy; García-Berro, E.
University: Universitat Autònoma de Barcelona

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Status: defended (05/12/2001)
Student: Josep Guerrero
Supervised by: Jordi Isern Vilaboy; García-Berro, E.
University: Universitat Autònoma de Barcelona

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The use of Global Navigation Satellite Systems (GNSS) signals in Numerical Weather Prediction

Status: defended (05/06/2001)
Student: Lídia Cucurull
Supervised by: Antonio Rius Jordán; Redaño, A.
University: Universitat de Barcelona

Not Available
Status: defended (05/06/2001)
Student: Lídia Cucurull
Supervised by: Antonio Rius Jordán; Redaño, A.
University: Universitat de Barcelona

Not Available

Atmospheric Tomography Using Satellite Radio Signals

Status: defended (04/02/2000)
Student: Alejandro Flores
Supervised by: Antonio Rius Jordán
University: Universitat Politècnica de Catalunya

The Global Navigation Satellite Systems (GPS and GLONASS) have become a basic tool to obtain geodetic measurements of the Earth and a source of data for the atmospheric analysis. Since these systems provide a global, dense and permanent coverage with precise and accurate data, the radio signals they…
Status: defended (04/02/2000)
Student: Alejandro Flores
Supervised by: Antonio Rius Jordán
University: Universitat Politècnica de Catalunya

The Global Navigation Satellite Systems (GPS and GLONASS) have become a basic tool to obtain geodetic measurements of the Earth and a source of data for the atmospheric analysis. Since these systems provide a global, dense and permanent coverage with precise and accurate data, the radio signals they transmit can be used for the spatio-temporal representation of the atmosphere. GPS receivers technology has evolved at a surprising pace: nowadays they have sufficient measurement quality as to be used in geodetic studies, together with other techniques such as the Very Long Base Interferometry (VLBI), and in atmospheric studies whose results can be input into meteorological analysis. In the thesis "Atmospheric Tomography Using Satellite Radio Signals" we have focused on the use of GPS system due to the better quality and quantity of references and tools for the data processing. This notwithstanding, we have proven the possibility to broaden the concept to include any other radio signal transmitting satellite system as an atmospheric sounder. The thesis has been divided into two main areas: GPS data processing to extract the information related to the atmospheric parameters under study, and the implementation of tomographic techniques to the solution of the inverse problem. In particular, tomography has been applied to the ionosphere and to the neutral atmosphere. In both cases, results have a socio-economic impact: a) monitoring the ionosphere is essential for radio transmissions across it because of the perturbations it may produce on the signal, and b) estimating water vapour content in the troposphere is highly useful for meteorological and climate forecast For the ionospheric tomography we initally only used the data from the global IGS network. Vertical resolution was afterwards improved using the occultation data of the GPS/MET experiment. The improvement, however, was limited to the region where these data existed. Finally, we used altimeter data from the TOPEX/POSEIDON satellite to improve the maps and to prove the radar altimeter calibration capability of the tomographic technique. The application to the troposphere was possible after the improvement and refinement of both the GPS data processing and the tomographic inversion. The first results were obtained using the experimental data from the permanent network in Kilauea, Hawaii. The particular geometry of the receivers in this local network made it highly suited for these initial results, which proved the possibility of obtaining spatio-temporal representations of the troposphere using GPS data. The data analysis of the REGINA campaign, which took place at the Onsala Space Observatory, provided the description of a complex meteorological phenomenon using only GPS data tropospheric tomography. We verified the results with a direct comparison with radiosonde data. Concluding, we have demonstrated the capabilities of atmospheric tomography using satellite radio signals, with particular emphasis on the GPS signals.

The motion sensing problem in spherical Gravitational Wave detectors

Status: defended (08/04/1999)
Student: Maria Angeles Serrano Moral
Supervised by: José Alberto Lobo Gutiérrez
University: Universitat de Barcelona

Not available
Status: defended (08/04/1999)
Student: Maria Angeles Serrano Moral
Supervised by: José Alberto Lobo Gutiérrez
University: Universitat de Barcelona

Not available
Institute of Space Sciences (IEEC-CSIC)

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Phone: +34 93 737 9788
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An institute of the Consejo Superior de Investigaciones Científicas

An institute of the Consejo Superior de Investigaciones Científicas
Affiliated with the Institut d'Estudis Espacials de Catalunya

Affiliated with the Institut d'Estudis Espacials de Catalunya