Obtención de microestructuras de grano ultrafino en aleaciones de aluminio mediante extrusión en canal angular (ECAE)

Al 5083 samples have been subjected to 90º equal-channel angular extrusion (ECAE) at 270ºC. After ECAE, the microhardness was measured and the texture for the plane perpendicular to the extrusion direction was analysed by X-Rays and EBSD. The microstructure was characterized by optical microscopy and EBSD. As deformation accumulates the hardness increases until it reaches saturation at an effective strain of about ε∼4. With regard to the texture, it has been shown that a high density of {111} planes are oriented parallel to the shear plane of the last pass.<br><br>Varias muestras de aluminio 5083 se han sometido a extrusiones en canal angular de 90º a 270ºC. A continuación se midieron las durezas de las muestras obtenidas y se caracterizó la textura en el plano perpendicular a la dirección de extrusión mediante Rayos-X y difracción de electrones retrodispersados (EBSD). La caracterización microestructural se hizo mediante microscopio óptico y EBSD. Se ha observado que la dureza aumenta sensiblemente con el grado de deformación y que alcanza un nivel máximo de saturación a partir de ε∼4. En cuanto a la textura, se observa que los planos {111} tienden a orientarse paralelos al plano de la última cortadura

Accurate circuit analysis of resonant-type left handed transmission lines with inter-resonator coupling

In this paper, a circuit model for the description of left handed transmission lines based on complementary split rings resonators CSRRs is proposed. As compared to previous models, coupling between adjacent resonators is included in the present work. The conditions that make this coupling significant are discussed. Specifically, it will be shown that it is barely present when circular CSRRs are used to implement the left handed transmission line. However, if the line is loaded with rectangular CSRRs separated by a small distance, inter-resonator coupling is important and it significantly influences the electromagnetic behavior of the structures. It will be also shown that under low or moderate coupling, it is possible to describe the structures by means of a simplified model with modified parameters. Several prototype devices with different CSRR topologies and coupling levels have been fabricated to illustrate the phenomenology associated with these structures and the accuracy of their model descriptions. The results of this work can be of interest for the design of planar microwave circuits based on CSRR left handed lines.Ministerio de Economía y Ciencias de España-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comisión Europea (Red de Excelencia)-E 500252-2 METAMORPHOS

Analysis of the linguistic expression I think in a corpus of late Modern English scientific texts

The present paper deals with the relationship between modality and evidentiality, focussed specifically on the use of the expression I think in combination with other modal devices, as well as the possible pragmatic effects observed in text samples obtained from the Coruña Corpus of English Scientific Writingand whether the variable of discipline might have some effect on the functions the expression represents in these texts.Even if much research is still to be done in academic texts from a diachronic perspective, there are some previous studies on stance devices carried out within the arena of historical pragmatics (cf. Gray, Biber and Hiltunen 2011; Moskowich and Crespo 2014; Alonso-Almeida 2015). Following this tradition, we focus on the expression I think, following the work of van der Auwera and Plungian (1998) for the description of modality and modal types.El presente trabajo trata sobre la relación entre modalidad y evidencialidad. Está centrado específicamente en el uso de la expresión I thinken combinación con otros elementos modales, así como los posibles efectos pragmáticos observados en muestras de textos obtenidas del Coruña Corpus of English Scientific Writing. Asimismo, analizamos si la variable de disciplina podría tener algún efecto sobre las funciones que la expresión lleva a cabo en estos textos. Aunque todavía queda mucho por investigar en textos académicos desde una perspectiva diacrónica, hay algunos estudios previos sobre elementos de posicionamiento realizados en el ámbito de la pragmática histórica (cf. Gray, Biber y Hiltunen 2011; Moskowich and Crespo 2014;Alonso-Almeida 2015). Siguiendo esta tradición, nos centramos en la expresión I think, siguiendo el trabajo de van der Auwera y Plungian (1998) para la descripción de la modalidad y los tipos modales

On the Transverse-Traceless Projection in Lattice Simulations of Gravitational Wave Production

It has recently been pointed out that the usual procedure employed in order to obtain the transverse-traceless (TT) part of metric perturbations in lattice simulations was inconsistent with the fact that those fields live in the lattice and not in the continuum. It was claimed that this could lead to a larger amplitude and a wrong shape for the gravitational wave (GW) spectra obtained in numerical simulations of (p)reheating. In order to address this issue, we have defined a consistent prescription in the lattice for extracting the TT part of the metric perturbations. We demonstrate explicitly that the GW spectra obtained with the old continuum-based TT projection only differ marginally in amplitude and shape with respect to the new lattice-based ones. We conclude that one can therefore trust the predictions appearing in the literature on the spectra of GW produced during (p)reheating and similar scenarios simulated on a lattice.Comment: 22 pages, 8 figures, Submitted to JCA

The planetary nebula IC 4776 and its post-common-envelope binary central star

We present a detailed analysis of IC 4776, a planetary nebula displaying a morphology believed to be typical of central star binarity. The nebula is shown to comprise a compact hourglass-shaped central region and a pair of precessing jet-like structures. Time-resolved spectroscopy of its central star reveals periodic radial velocity variability consistent with a binary system. While the data are insufficient to accurately determine the parameters of the binary, the most likely solutions indicate that the secondary is probably a low-mass main sequence star. An empirical analysis of the chemical abundances in IC 4776 indicates that the common-envelope phase may have cut short the AGB evolution of the progenitor. Abundances calculated from recombination lines are found to be discrepant by a factor of approximately two relative to those calculated using collisionally excited lines, suggesting a possible correlation between low abundance discrepancy factors and intermediate-period post-common-envelope central stars and/or Wolf-Rayet central stars. The detection of a radial velocity variability associated with binarity in the central star of IC 4776 may be indicative of a significant population of (intermediate-period) post-common-envelope binary central stars which would be undetected by classic photometric monitoring techniques.Comment: Accepted for publication in MNRA

Manual for inspection of sprayers in use and PRITEAF, dedicated software for inspection of sprayers: success tools developed for the inspector’s training process in Spain

Software dedicated to inspection of sprayers in use has been developed with the aim to facilitate the accomplishment of the mandatory requirements from EU Directive for a Sustainable Use of Pesticides, specifically those concerning the inspection of sprayers in use. The software- PRITEAF- has been developed according to the European standards EN 13790 concerning mandatory inspection of sprayers in use and it is ready to be used not only for inspectors among all the EU members but also for training purposes all over the world. The software is ready to be on line –after minor arrangements - with the recently approved new international inspection standards ISO 16122, and its main features are: to facilitate the sprayer’s inspection procedure, to manage, storage and transfer all the information to the official bodies in charge of the procedure, and to be used as a support tool to improve the training activities during the process, according the European Directive 2009/128/CE for a Sustainable Use of Pesticides. For this purpose, PRITEAF has been designed for three different types of users: inspection teams, inspection workshops and regional authorities. PRITEAF has been developed using the File Maker Pro package and it is composed of three databases – inspections activities, database on sprayers already inspected, and owners or official responsible for the agricultural activity. The software is completed with specific modules for data acquisition and for generating official reports, files and communications. For its implementation, PRITEAF uses specific hardware (a PC server, a tablet and local Wi-Fi) necessary to ensure proper data collection in the field. After data collection, the software generates an official inspection report and an inspection certificate, as required by law. Using PRITEAF reduces inspection time by 33% compared to traditional sprayer inspection systems. Following its validation, PRITEAF has been made available to regional authorities and inspection workshops across Spain, and is also being used to train all inspection teams in the country. More than 800 inspectors have been officially trained using the developed software, resulting in an interesting tool to improve the daily activities to be executed in all the inspection’s workshops in Europe