3,635 research outputs found
Classification and localization of electromagnetic and ultrasonic pulsed emitters
Mención Internacional en el título de doctorThe localization of radiative sources is very important in many fields of work such
as: sonar, radar and underwater radar, indoor localization in wireless networks, earthquake
epicenter localization, defective assets localization in electrical facilities and so
forth. In the process of locating radiative sources exist many issues which can provoke
errors in the localization. The signals acquired may belong to different sources or they
can be mixed with environmental noise, then, their separation before using localization
algorithms is of great interest to be efficient and accurate in the computational process.
Furthermore, the geometry and radiation characteristics of the receivers, the nature of
the signal or their measuring process may cause deviations in the signal onset calculus
and therefore the source localization could be displaced from the actual position.
In this thesis, there are three kinds of algorithms to undertake three steps in the
emitter localization: signal separation, onset and time delay estimation of the signals
and source localization. For each step, in order to reduce the error in the localization,
several algorithms are analyzed and compared in each application, to choose the most
reliable.
As the first step, to separate different kinds of signals is of interest to facilitate further
processing. In this thesis, different optimization techniques are presented over the
power ratio (PR) maps method. The PR uses a selective spectral signal characterization
to extract the features of the analyzed signals. The technique identifies automatically
the most representative frequency bands which report a great separation of the different
kinds of signals in the PR map.
After separating and selecting the signals, it is of interest to compare the algorithms
to calculate the onset and time delay of the pulsed signals to know their performance
because the time variables are inputs to the most common triangulation algorithms to
locate radiative and ultrasonic sources. An overview of the algorithms used to estimate
the time of flight (ToF) and time differences of arrival (TDoA) of pulsed signals is done
in this thesis. In the comparison, there is also a new algorithm based on statics of high
order, which is proposed in this thesis. The survey of their performance is done applied
to muscle deep estimation, localization in one dimension (1D), and for the localization
of emitters in three dimensions (3D). The results show how the presented algorithm
yields great results.
As the last step in the radiative source localization, the formulation and principle
of work of both iterative and non-iterative triangulation algorithms are presented. A
new algorithm is presented as a combination of two already existing improving their
performance when working alone. All the algorithms, the proposed and the previous
which already exist, are compared in terms of accuracy and computational time. The
proposed algorithm reports good results in terms of accuracy and it is one of the fastest
in computational time.
Once the localization is achieved, it is of great interest to understand how the errors
in the determination of the onset of the signals are propagated in the emitter localization.
The triangulation algorithms estimate the radiative source position using
time variables as inputs: ToF, TDoA or pseudo time of flight (pToF) and the receiver
positions. The propagation of the errors in the time variables to the radiative source localization
is done in two dimensions (2D) and 3D. New spherical diagrams have been
created to represent the directions where the localization is more or less sensible to the
errors. This study and their sphere diagrams are presented for several antenna layouts.
Finally, how the errors in the positioning of the receivers are propagated to the
emitter localization is analyzed. In this study, the effect in the propagation of both
the relative distance from the receivers to the emitter and the direction between them
has been characterized. The propagation of the error considering the direction is also
represented in spherical diagrams. For a preferred direction identified in the spheres,
the propagated error in the source localization has been quantified regarding both the
source distance and the magnitude of the errors in the receivers positioning.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Andrea Cavallini.- Secretario: José Antonio García Souto.- Vocal: Iliana Portugués Peter
Methodology of analysis and evaluation of websites 2.0. The case of the Andalusian Dioceses
La acelerada evolución del ciberespacio y la volatilidad tanto de los sitios web como de
los medios online requiere una permanente adecuación de las técnicas y de los métodos de estudio.
Hemos desarrollado un nuevo modelo de análisis, unificando propuestas anteriores y completándolo
con un sistema de validación de resultados contrastado. Afrontamos la investigación desde una
perspectiva global y en consonancia con la Web 2.0 y los medios sociales.
Para ello partimos del Website Communication Model (WCM), desarrollado por Juan Narbona,
que analiza los sitios webs utilizando cuatro pilares: contenidos y servicios, instrumentos técnicos,
promotores y visitantes. Dicho modelo, válido para la Web 1.0, fue actualizado por Daniel Arasa en el
Online Communication Model (OCM), que añade un quinto pilar para contemplar los medios sociales.
Y para completarlo nos apoyamos en un sistema de medición cuantitativa tan contrastado como el
Sistema Articulado de Análisis de Cibermedios (SAAC).The rapid cyberspace evolution and the volatility of both, websites as well as online
media requires an ongoing education of the technique and study methods. We have developed a new
model of analysis, unifying previous designs and completing it with a contrasted results validation
system. We confront this query from a global perspective and in line with Web 2.0 and social media.
For this we start from the Communication Model Website (WCM), developed by Juan Narbona, which
analyzes websites using four pillars: content and services, technical instruments, promoters and
visitors. This model, valid for Web 1.0, was updated by Daniel Arasa in the Online Communication
Model (OCM), which adds a fifth pillar to contemplate social media Also take into account we lean
on a quantitative method measurement system the Sistema Articulado de Análisis de Cibermedios
(SAAC), for further validation
Differentiation Between Ripening Stages of Iberian Dry-Cured Ham According to the Free Amino Acids Content
In this paper, the differentiation of three ripening stages, postsalting, drying, and cellar, of Iberian dry-cured ham has been carried out according to their free amino acids contents. Eighteen L-amino acids, alanine, 2-aminobutanoic acid, aspartic acid, cysteine, glutamine, glycine, histidine, hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, and valine have been determined by gas chromatography with derivatization with N,O-bis(trimethylsilyl)-trifluoroacetamide. Gas chromatography-mass spectrometry was used to confirm the presence of the eighteen amino acids in the ham samples, and gas chromatography using a DB-17HT column and flame ionization detector was used for quantitative determination. Extraction with a mixture methanol-acetonitrile has been carried out, achieving recoveries in the range 52-164%. Methimazole was used as internal standard. Limits of detection ranged between 7.0 and 611.7 mg·kg-1. Free amino acids have been used as chemical descriptors to differentiate between the ripening stages. Principal component analysis and linear discriminant analysis have been used as chemometric techniques, achieving complete differentiation between the ripening stages. Alanine, tyrosine, glutamine, proline, 2-aminobutanoic acid, cysteine, and valine were the most differentiating amino acids.Junta de Andalucía the project P09-AGR-0478
The digital maturity of the Spanish press. A case study
Buscamos un método fiable para medir el índice de madurez digital (IMD) de la prensa española. Metodología: Utilizamos el método del caso, con un estudio del diario Abc. Nos basamos en datos cuantitativos y cualitativos. En cuanto a las técnicas hemos combinado las entrevistas, con la observación participante y la consulta a expertos. Resultados: El modelo se ha ensayado con éxito y es aplicable al estudio de cualquier medio informativo. El diario Abc registra a 31 julio 2018 un Índice de Madurez Digital, de 72,50 puntos sobre un máximo de 100. Significa que se encuentra en un estado Avanzado de madurez digital. Conclusiones: La Prensa española, representada en este caso por la cabecera nacional de Vocento, se encuentra en un proceso bastante avanzado de transformación y madurez digital, aunque aún queda camino para que la Web marque las rutinas más importantes del trabajo periodístico.This research aims to set a reliable methodology to measure the digital maturity index (IMD) of the Spanish press. Methodology: For the analysis we are using the case method, with a focus on Abc newspaper. We rely on quantitative and qualitative data. In terms of techniques, we have combined interviews, participant observation and expert consultation. Results: The model has been successfully tested and is fully applicable to any other newspaper. ABC holds at July, 31st 2018 a Digital Maturity Index of 72.50 points out of a maximum of 100. It means an advanced state of digital maturity. Conclusions: The Spanish Press, represented in this research by Abc —a brand of Vocento Group— is nowadays in an advanced process of transformation and digital maturity, although there is still a room for improvement for the website to become the backbone for the most important routines of journalism
A hydrated ion model of [UO2]2+ in water: Structure, dynamics, and spectroscopy from classical molecular dynamics
A new ab initio interaction potential based on the hydrated ion concept has been developed to obtain
the structure, energetics, and dynamics of the hydration of uranyl in aqueous solution. It is the first
force field that explicitly parameterizes the interaction of the uranyl hydrate with bulk water molecules
to accurately define the second-shell behavior. The [UO2(H2O)5
]
2+
presents a first hydration shell
U–O average distance of 2.46 Å and a second hydration shell peak at 4.61 Å corresponding to 22
molecules using a coordination number definition based on a multisite solute cavity. The second
shell solvent molecules have longer mean residence times than those corresponding to the divalent
monatomic cations. The axial regions are relatively de-populated, lacking direct hydrogen bonding to
apical oxygens. Angle-solved radial distribution functions as well as the spatial distribution functions
show a strong anisotropy in the ion hydration. The [UO2(H2O)5
]
2+
solvent structure may be regarded
as a combination of a conventional second hydration shell in the equatorial and bridge regions, and
a clathrate-like low density region in the axial region. Translational diffusion coefficient, hydration
enthalpy, power spectra of the main vibrational modes, and the EXAFS spectrum simulated from
molecular dynamics trajectories agree fairly well with the experiment.Junta de Andalucía de España, Proyecto de Excelencia-P11-FQM 760
A general study of actinyl hydration by molecular dynamics simulations using ab initio force fields
A set of new ab initio force fields for aqueous [AnO2]
2+/+ (An = Np(VI,V), Pu(VI), Am(VI)) has been developed using the Hydrated Ion
(HI) model methodology previously used for [UO2]
2+. Except for the non-electrostatic contribution of the HI-bulk water interaction, the
interaction potentials are individually parameterized. Translational diffusion coefficients, hydration enthalpies, and vibrational normal mode
frequencies were calculated from the MD simulations. Physico-chemical properties satisfactorily agree with experiments validating the robustness of the force field strategy. The solvation dynamics and structure for all hexavalent actinoids are extremely similar and resemble our
previous analysis of the uranyl cation. This supports the idea of using the uranyl cation as a reference for the study of other minor actinyls. The
comparison between the NpO2+
2 and NpO+
2 hydration only provides significant differences in first and second shell distances and second-shell
mean residence times. We propose a single general view of the [AnO2]
2+/+ hydration structure: aqueous actinyls are amphiphilic anisotropic
solutes which are equatorially conventional spherically symmetric cations capped at the poles by clathrate-like water structures.Junta de Andalucía de España, Plan Andaluz de Investigación-FQM-28
Field Fluctuations and Casimir Energy of 1D-Fermions
Producción CientíficaWe investigate the self-adjoint extensions of the Dirac operator of a massive one-dimensional
field of mass m confined in a finite filament of length L. We compute the spectrum of vacuum
fluctuations of the Dirac field under the most general dispersionless boundary conditions. We identify
its edge states in the mass gap within a set of values of the boundary parameters, and compute the Casimir energy of the discrete normal modes. Two limit cases are considered, namely, that of light fermions with mL 1, and that of heavy fermions for which mL 1. It is found that both positive and negative energies are obtained for different sets of values of the boundary parameters. As a consequence of our calculation we demonstrate that the sign of the quantum vacuum energy is not
fixed for exchange-symmetric plates (parity-invariant configurations), unlike for electromagnetic and
scalar fields.Ministerio de Economía, Industria y Competitividad (grant MTM2014-57129-C2-1-P)Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (grants VA057U16 and BU229P18)Junta de Castilla y León (grant VA137G18
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