Un nuevo horizonte: la evaluación por competencias en el Espacio Europeo de Educación Superior

En los últimos años las Universidades han experimentado importantes cambios en el modelo existente, con motivo del marco definido por Bolonia. Este artículo pone de manifiesto la necesidad de un cambio en el proceso de evaluación, debido a la entrada de un nuevo elemento: las competencias (preestablecidas) que el estudiante debe adquirir a lo largo del proceso de formación. La evaluación de las mismas supondrá un cambio en la concepción clásica basada en una evaluación final y centrada en un mero examen del resultado obtenido. Por el contrario, la evaluación se convierte, a partir de ahora, en un proceso continuo que facilitará al docente información permanente sobre la progresión del alumno

Study and control of turbulent transport in the Boundary Plasma region of the TJ-II stellarator and the JET tokamak

Mención Internacional en el título de doctorThermonuclear fusion has been proposed as a sustainable, clean and safe energy source to meet the energy demands of the future. There are, however, still several challenges that need to be overcome in order to realize a viable fusion power plant. One of the great challenges is the integration of physics and technology optimization. Performance of magnetic fusion reactors is limited by heat and particle losses. The heat and particle losses are understood to be governed by the non-linear interplay of turbulence and plasma flows but uncertainty remains on e.g. physics of the sudden transitions between confinement regimes, isotopic scaling of confinement, non-linear saturation mechanisms of plasma turbulence, power exhausts and plasma-wall interaction. This thesis investigates the interplay of flows and turbulence in the TJ-II stellarator and the influence of magnetic configuration on plasma-wall interaction in the JET tokamak. A deep understanding of the mechanisms leading to turbulence self-regulation via Zonal Flows (ZFs) is of paramount importance. In this sense, the assessment of Long Range Correlations (LRC) in the plasma edge, by the use of Langmuir probe systems, have been proven to be a powerful strategy to study the interaction between ZFs and turbulence. Improvements in the experimental strategy to characterize LRC have been applied to study the interplay between neoclassical radial electric fields and ZFs and the transition to improved confinement regimes in the TJ-II stellarator. Experimental studies reveal the role of neoclassical radial electric fields to control the amplitude of Zonal Flows resulting in the development of both long (neoclassical) and short (due to Zonal Flows) radial electric field scales with important implication in the physics understanding of transport self-regulation mechanisms. A comprehensive description of the influence of plasma scenarios on the radial width of ZFs is given here, with a special focus on its dependence with heating and isotope scaling. For the first time, the characterization of low frequency fluctuating ZFs and mean radial electric fields has been experimentally studied during the L-H transition in Hydrogen and Deuterium plasmas in the stellarator TJ-II. No evidence of isotope effect on the L-H transition dynamics was observed. These observations emphasize the critical role of both zero frequency (equilibrium) and low frequency varying large-scale flows for stabilizing turbulence during the triggering of the L-H transition in magnetically confined toroidal plasmas and show that there are different paths to reach the L-H transition with impact on the conditions to access the H-mode regime. In addition to the relevance of studies carried out in stellarators, experimental validation of relevant plasma scenarios in large tokamaks constitute the fundamental test bench for future burning fusion reactors such as ITER. For example in the last years it has been shown that, in the JET tokamak, with the new ITER-like wall, global plasma confinement is strongly linked to the divertor magnetic topology, which influences the Boundary Plasma and the Plasma Wall Interaction. In this Thesis we show a study on how the neutral fluxes are affected by the divertor magnetic configuration and, as a consequence, how the SOL plasma changes. We also present a detailed preliminary analysis of the dynamic behavior of Ion and Neutral fluxes during the ELM-cycle. The results point to the Recycling coefficient, which varies significantly within this short time-scale, something that could have important implications in the understanding of the H-mode performance.El aprovechamiento de la energía de la fusión termonuclear se ha propuesto como un método limpio y sostenible para hacer frente a las demandas energéticas futuras. Sin embargo, actualmente todavía se deben superar retos científicos y técnicos para hacer viable la operación de un reactor nuclear de fusión. Uno de los mayores retos es el entendimiento de la física del plasma que tiene lugar en los reactores de fusión así como la optimización tecnológica de los propios reactores. El rendimiento de los futuros reactores de fusión está limitado por las pérdidas de partículas y de calor. Ambos fenómenos están gobernados por la interacción no lineal entre la turbulencia del plasma y los flujos a gran escala, conocidos como Flujos Zonales. Por otra parte, la física de las transiciones espontáneas entre regímenes de diferente nivel de confinamiento, el efecto isotópico y sus implicaciones, los mecanismos de saturación no lineal de la turbulencia así como la evacuación de los flujos de calor y la física de la interacción entre el plasma y la pared necesita todavía ser entendida. Esta tesis describe la investigación empírica de la interacción entre las diferentes escalas de turbulencia de plasma en el stellarator TJ-II y la influencia de la configuración magnética en la física de la interacción plasma-pared en el tokamak JET. A este efecto, se han utilizado dos diagnósticos: las sondas electrostáticas (conocidas como sondas de Langmuir) y espectroscopía rápida en el espectro visible. Es de suma importancia la comprensión profunda de los mecanismos que conducen a la autorregulación de la turbulencia por la acción de los Flujos Zonales (ZF). En este sentido, se ha demostrado que la evaluación de las correlaciones de largo alcance (LRC) en el borde del plasma, mediante el uso de los sistemas de sondas de Langmuir, es una estrategia poderosa para estudiar la interacción entre ZF y la turbulencia. Las mejoras en la estrategia experimental para caracterizar LRC se han aplicado para estudiar la interacción entre los campos eléctricos radiales neoclásicos ZF durante la transición a regímenes de confinamiento mejorados en el stellarator TJ-II. Los estudios experimentales llevados a cabo revelan el papel de los campos eléctricos radiales neoclásicos en el control de la amplitud de los flujos zonales que resultan en el desarrollo de escalas de campos eléctricos radiales largos (neoclásicos) y cortos (debidos a los flujos zonales), con una importante implicación en la comprensión física de los mecanismos de auto-regulación transporte radial. Aquí se proporciona una descripción completa de la influencia de los escenarios de plasma en el ancho radial de las ZF, con un enfoque especial en su dependencia con el calentamiento y la masa isotópica. Por primera vez, la caracterización de estas fluctuaciones globales de baja frecuencia y campos eléctricos radiales se ha estudiado experimentalmente durante la transición L-H en plasmas de hidrógeno y deuterio en el stellarador TJ-II. No se observó evidencia de efecto isótopo en la dinámica de transición L-H. Estas observaciones enfatizan el papel crítico del campo eléctrico neoclásico (o de equilibrio) y los flujos a gran escala de baja frecuencia para estabilizar la turbulencia durante el inicio de la transición L-H en plasmas toroidales confinados magnéticamente. Esto muestra que existen diferentes caminos para alcanzar la transición de LH con impacto sobre las condiciones de acceso al régimen de confinamiento mejorado. Además de la relevancia de los estudios realizados en stellarators, la validación experimental de escenarios relevantes de plasma en grandes tokamaks constituye el banco de pruebas fundamental para futuros reactores de fusión como ITER. Por ejemplo, en los últimos años se ha demostrado que, en el tokamak JET, con la nueva pared, que es idéntica a la que estará instalada en ITER, el confinamiento global del plasma está fuertemente vinculado a la topología del divertor, lo que influye en la física y en las características del borde del plasma y de la interacción plasma-pared. En esta tesis, mostramos un estudio sobre cómo los flujos de partículas neutras se ven afectados por la configuración magnética del divertor y, en consecuencia, cómo cambia la parte más externa del plasma, en la que las líneas de campo no están cerradas sobre sí mismas, sino que se cierran a través de los elementos metálicos del dispositivo, conocida como “Scrape-Off Layer”. También presentamos un análisis preliminar detallado del comportamiento dinámico de los flujos de iones y neutros durante las inestabilidades de tipo ELM. Los resultados apuntan al coeficiente de reciclado, que varía significativamente dentro de esta breve escala de tiempo, algo que podría tener implicaciones importantes en la comprensión del rendimiento en modo de alto confinamiento.Este trabajo se ha realizado en el marco del proyecto ENE2012-38620-C02-01 (referencia BES-2013-065215), del Ministerio de Ciencia, Innovación y Universidades (MICINN).Programa Oficial de Doctorado en Plasmas y Fusión Nuclear por la Universidad Carlos III de MadridPresidente: Luis Conde López.- Secretario: Isabel García Cortés.- Vocal: Alexander Vladimirovich Melniko

Rational characteristic functions and markov chains

Abstract 1 We investigate in this paper how to estimate the density function of a random variable using a parametric ARMA model for its characteristic function. The choice of this model is motivated by the fact that this type of density characterizes the duration of staying at an N-states Markov chain, but the approach is general enough to be applied to many practical problems. Both ML and moment-based linear estimates are derived, the former being based on the optimization of a highly non-linear function. 1.Peer ReviewedPostprint (published version

Emitter discharge variability of subsurface drip irrigation in uniform soils: effect on water-application uniformity

Emitter discharge of subsurface drip irrigation (SDI) decreases as a result of the overpressure in the soil water at the discharge orifice. In this paper, the variation in dripper discharge in SDI laterals is studied. First, the emitter coefficient of flow variation CVq was measured in laboratory experiments with drippers of 2 and 4 L/h that were laid both on the soil and beneath it. Additionally, the soil pressure coefficient of variation CVhs was measured in buried emitters. Then, the irrigation uniformity was simulated in SDI and surface irrigation laterals under the same operating conditions and uniform soils; sandy and loamy. CVq was similar for the compensating models of both the surface and subsurface emitters. However, CVq decreased for the 2-L/h non-compensating model in the loamy soil. This shows a possible self-regulation of non-compensating emitter discharge in SDI, due to the interaction between effects of emitter discharge and soil pressure. This resulted in the irrigation uniformity of SDI non-compensating emitters to be greater than surface drip irrigation. The uniformity with pressure-compensating emitters would be similar in both cases, provided the overpressures in SDI are less than or equal to the compensation range lower limit

Evaluating a human-robot interface for exploration missions

The research reported in this paper concerns the design, implementation, and experimental evaluation of a Human-Robot Interface for stationary remote operators, implemented for a PC computer. The GUI design and functionality is described. An Autonomy Management Model has been implemented and explained. We have conducted user evaluation, making two set of experiments, that will be described and the resulting data analyzed. The conclusions give an insight on the most important usability concerns, regarding the operator situational awareness. The scalability of the interface is also experimentally studied

Nanocrystalline glass-like carbon thin films may be an useful tool in nerve cells regeneration

Abstract en el libro de Abstract de la International Conference, p. 99The interest in carbon nanomaterials with high transparency and electrical conductivity has grown within the last decade in view of a wide variety of applications, including biocompatible sensors, diagnostic devices and bioelectronic implants. The aim of this work is to test the biocompatibility of particular nanometer-thin nanocrystalline glass-like carbon films (NGLC), a disordered structure of graphene flakes joined by carbon matrixUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. We thank Prof. Arenas, Karolinska Institutet, Stockholm, Sweden, for SN4741 cell line. R.G.V. gratefully acknowledges Spanish Ministry of Science and Innovation for funding through a Ramon y Cajal fellowship

The selection of directional sectors for the analysis of extreme wind speed

This paper presents a rational method for the selection of the most suitable directional sectors in the analysis of extreme wind loads on structures. It takes into consideration the main sources of uncertainty stemming from sector selection and leads to the definition of independent and statistically homogeneous directional sectors. This method is applied to the selection of directional sectors for the calculation of the design wind speed of a structure located at the mouth of the Río de la Plata. The results in the estimated reliability and costs were compared to those obtained with conventional engineering methods, revealing significant differences. It was found that the proposed method is a simple and objective tool for the selection of directional sectors, which comply with the working hypothesis of the directional models, and offers better guarantees for dimensioning than the use of more traditional engineering approaches for sectorial division.The doctoral studies that led to this work were partially funded by Abengoa Research within the framework of a cooperation agreement between the company and the Environmental Fluid Dynamics Research Group of the University of Granada

Experiments on the Sinking of Marine Pipelines on Clayey Soils

This research was funded by AREDIS project from the European Regional Development Fund, NSRF-National strategic reference framework (2007-2013 Portugal) and the Regional operational program PORLISBOA, the Consejo Nacional de Ciencia y Tecnologia (CONACYT) of Mexico and the Centro para el Desarrollo Tecnologico Industrial (CDTI) of Spain under contract C0004-201201 143095. The APC was funded by CONACYT-SENER/Sustentabilidad Energetica through the Centro Mexicano de Inovacion en Energias del Oceano (CEMIE-Oceano), grant number 249795.An experimental study was carried out to investigate seabed-pipeline interactions with regard to soil liquefaction. For a soil with a high proportion (30 to 60%) of fine sediment, four groups of tests were configured to reproduce soil liquefaction around pipelines for different initial pipe depths, pipe densities and wave conditions (wave height and period). The study focused on verifying the theoretically computed areas of soil failure by analyzing the sinking depths of the pipelines. The main findings are that a pipe with a submerged specific weight of less than half that of the soil will move up to the mudline; that the loss of soil loading capacity is more frequently evidenced in a fluid-like behavior of the soil than by an abrupt breaking of the soil matrix; and that the pipes which are totally buried will sink more than half-buried pipes. Moreover, wave action and the specific weight of the pipes seem to play more important roles in the expected behavior of the wave–soil–pipe interaction than the initial water content of the mud.AREDIS project from the European Regional Development FundNSRF-National strategic reference framework (2007-2013 Portugal)Regional operational program PORLISBOAConsejo Nacional de Ciencia y Tecnologia (CONACyT)Centro para el Desarrollo Tecnologico Industrial (CDTI) of Spain C0004-201201 143095CONACYT-SENER/Sustentabilidad Energetica through the Centro Mexicano de Inovacion en Energias del Oceano (CEMIE-Oceano) 24979