3,183 research outputs found

    Nonequilibrium Phase Transitions in Directed Small-World Networks

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    Many social, biological, and economic systems can be approached by complex networks of interacting units. The behaviour of several models on small-world networks has recently been studied. These models are expected to capture the essential features of the complex processes taking place on real networks like disease spreading, formation of public opinion, distribution of wealth, etc. In many of these systems relations are directed, in the sense that links only act in one direction (outwards or inwards). We investigate the effect of directed links on the behaviour of a simple spin-like model evolving on a small-world network. We show that directed networks may lead to a highly nontrivial phase diagram including first and second-order phase transitions out of equilibrium.Comment: 4 pages, RevTeX format, 4 postscript figs, uses eps

    Sin rumbo aparente. La evolución estética de las hogueras de Alicante

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    [ES] La pérdida de identidad en las hogueras de San Juan de Alicante es el desencadenante del presente TFG. En él se aborda la corriente estética imperante en las estructuras efímeras durante los inicios como fiesta oficial de la ciudad, haciendo especial hincapié durante la madurez de la misma, en la década de los cincuenta, y el detonante que rompió la evolución lógica de las hogueras. A partir de esta investigación se ha realizado un proyecto personal de hoguera adulta basada en las formas de este tipo de estructuras efímeras tomando como base diversos referentes artísticos dentro del mundo de las hogueras, algunos de la época investigada, y otros contemporáneos.[EN] The loss of identity in the ¿las hogueras de San Juan¿ in Alicante is the trigger for the present TFG. It deals with the prevailing aesthetic current in the ephemeral structures during the beginning as an official festival of the city, making special emphasis during the maturity of the same in the fifties and the trigger that broke the logical evolution of the ¿hogueras¿. From this research, a ¿hoguera¿ project based on the forms of this type of ephemeral structures has been carried out based on various artistic references within the world of ¿hogueras¿, some from the investigated period and others contemporaries.Lopez Sanchez, A. (2020). Sin rumbo aparente. La evolución estética de las hogueras de Alicante. http://hdl.handle.net/10251/144017TFG

    Range Spectral Filtering in SAR Interferometry: Methods and Limitations

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    A geometrical decorrelation constitutes one of the sources of noise present in Synthetic Aperture Radar (SAR) interferograms. It comes from the different incidence angles of the two images used to form the interferograms, which cause a spectral (frequency) shift between them. A geometrical decorrelation must be compensated by a specific filtering technique known as range filtering, the goal of which is to estimate this spectral displacement and retain only the common parts of the images’ spectra, reducing the noise and improving the quality of the interferograms. Multiple range filters have been proposed in the literature. The most widely used methods are an adaptive filter approach, which estimates the spectral shift directly from the data; a method based on orbital information, which assumes a constant-slope (or flat) terrain; and slope-adaptive algorithms, which consider both orbital information and auxiliary topographic data. Their advantages and limitations are analyzed in this manuscript and, additionally, a new, more refined approach is proposed. Its goal is to enhance the filtering process by automatically adapting the filter to all types of surface variations using a multi-scale strategy. A pair of RADARSAT-2 images that mapped the mountainous area around the Etna volcano (Italy) are used for the study. The results show that filtering accuracy is improved with the new method including the steepest areas and vegetation-covered regions in which the performance of the original methods is limited.This work was supported by the Spanish Ministry of Science and Innovation (State Agency of Research, AEI) and the European Funds for Regional Development (ERFD) under Projects PID2020-117303GB-C21 and PID2020-117303-C22

    An Improved Phase Filter for Differential SAR Interferometry Based on an Iterative Method

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    Phase quality is a key element in the analysis of the deformation of the Earth's surface carried out with differential synthetic aperture radar interferometry. Various decorrelation sources may degrade the surface deformation estimates, and thus, phase filters are needed for this kind of application. The well-known Goldstein filter is the most widely used due to its simple implementation and computational efficiency. In the past years, improved filters have been proposed, which are based on this filter but introduce variations in the data processing. The effectiveness of these filters mostly depends on the size of the filtering window, the weight of the smoothed spectrum, and the kernel used to filter the spectrum. In this paper, we evaluate the performance of four of these filters and present a new method that outperforms all of them. The proposed filter is based on an iterative method in which the original phase is denoised progressively with adaptive filtering windows of different sizes. The effectiveness of the filter is controlled by the interferometric coherence, a direct indicator of the phase quality. Moreover, we introduce some modifications regarding the processing of the power spectrum. Specifically, we propose to smooth the original phase using a new filter which is based on a Chebyshev interpolation scheme. The performance of the new filter has been tested on both simulated and real interferograms, acquired by RADARSAT-2 and the Uninhabited Aerial Vehicle Synthetic Aperture Radar, which mapped two different geological events that caused surface deformation.This work was supported in part by the Spanish Ministry of Economy, Industry and Competitiveness, in part by the State Agency of Research (AEI), in part by the European Funds for Regional Development under Project TIN2014-55413-C2-2-P and Project TEC2017-85244-C2-1-P, in part by the U.K. Natural Environmental Research Council through the Looking Inside the Continents under Grant NE/K011006/1, in part by the Rapid deployment of a seismic array in Ecuador following the April 16th 2016 M7.8 Pedernales earthquake under Grant NE/P008828/1, and in part by the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics under Grant COMET, GA/13/M/031

    A New Educational Escape-Room-Based Model for the Sustainable Valorization and Management of Cultural and Natural Heritage

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    Based on the model of the “escape room” game, the activity proposed in this paper centres on the historical site of one of the fiercest battles of the Spanish Civil War (February 1937). The battle site is in the area of Rivas-vaciamadrid, the focal point of the Francoist and Republican camps, which connected the centre of Madrid with one of the city’s most important logistics and military facilities, Alcalà de Henares. The study proposes a new way to use the site and, in particular, proposes a live game aimed at involving different types of participants, aligning it with their specific profiles, whether children, adults or scholars. Its main aim is to propose an activity for the sustainable valorization of this heritage and to raise awareness in participants about this significant piece of history as well as its preservation in the long-term. It should be kept in mind that “Los pueblos que desconocen su Historia están condenados a repetirla”, i.e. “Those who do not know their history are doomed to repeat it”.The Rivas-vaciamadrid site is also a source of information and study regarding geological, natural and historical-artistic aspects. One example is the Porphyrio porphiyrio (western swamphen), present in the ecosystem of Rivas-vaciamadrid, which has a noteworthy past having been depicted in the mosaics of both the "Villa Romana del Casale" in Sicily and the Church of "San Vitale", in Ravenna, Italy as well as being reported in writings by Aristotle and Pliny the Elder

    Evolución histórica de los vehículos aéreos no tripulados hasta la actualidad

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    The origin and development of unmanned aviation has been almost matched that of manned aviation, starting both from an almost common point. As in conventional manned aviation, military applications, have been the motor of technological development and the potential applications of these types of systems throughout much of the twentieth century and early twenty-first century. Finally it has been in relatively recent times that these systems are experiencing an impressive boom due to the discovery of the wide variety of commercial and civil operations that are able to perform very effectively. This paper attempts to summarize the historical evolution that these systems have suffered and in the end, to present a quick analysis of the major civil / commercial applications, trying to provide an overview of the main types of systems, their classification and general configuration.Peer Reviewe

    Characterization of nanostructured SnO2 films deposited by reactive DC-magnetron sputtering

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    Nanostructured tin oxide thin films were deposited on silicon and glass slides substrates by reactive DC-Magnetron sputtering using a tin target in a mixture of argon and oxygen gases. The substrate temperature was varied in the range from 53 to 243 oC, keeping the other deposition parameters constant. The tin oxide films were characterized by: Scanning Electron Microscopy, Energy Dispersive Spectrometry, X Ray Diffraction, microRaman spectroscopy and UV-VIS spectroscopy. It was found that the substrate temperature has an effect mainly on the structural, morphological and optical properties of the thin films. At 53 and 90 oC the tetragonal crystalline phase was obtained while a mixture of crystalline phases (o-SnO2 and t-SnO2) was obtained at 148, 185 and 243 oC

    Profile of the Spatial Distribution Patterns of the Human and Bacteriophage Virome in a Wastewater Treatment Plant Located in the South of Spain

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    The authors would like to acknowledge the support given by the Institute of Water Research of University of Granada and the disposition of Municipal Water Company of Granada (EMASAGRA S.A.) for financial support to carry out the research.In wastewater treatment plants, most microbial characterization has focused on bacterial, archaeal, and fungal populations. Due to the difficult isolation, quantification, and identification of viruses, only a limited number of virome studies associated with wastewater treatment plants have been carried out. However, the virus populations play an important role in the microbial dynamics in wastewater treatment systems and the biosafety of effluents. In this work, the viral members present in influent wastewater, mixed liquor (aerobic bioreactor), excess sludge, and effluent water of a conventional activated sludge system for the treatment of urban wastewater were identified. Viral members were observed by transmission electron microscopy and studied through next-generation sequencing studies. The results showed the dominance of bacteriophages in the viral community in all samples, with the dominant viral phylotype classified as Escherichia coli O157 typing phage 7. Moreover, different human viruses, such as Cynomolgus cytomegalovirus and Gammaherpesvirus, were also detected.Institute of Water Research of University of Granad

    Critical plane based method for multiaxial fatigue analysis of 316 stainless steel

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    In this work, the fatigue behaviour of 316 stainless steel is studied with different critical plane models. Seven cylindrical samples were used for the study, being subjected to different complex loading paths, generating combined stresses along the axial and transversal sample directions, these being: individual axial stress, individual hoop stress, alternating axial and hoop stress, a proportional combination of axial and hoop stress, and a non-proportional combination of L-shaped and square-shaped axial and hoop stress. The fatigue analysis is performed using five critical plane models; named Fatemi-Socie, Varvani-Farahani, Gan-Wu-Zhong, Liu I and Liu II. The models were assessed based on their fatigue life and crack angle prediction capacity. The Gan-Wu-Zhong recently proposed critical plane model was examined and provided acceptable results for the multiaxial loads tested on 316 steel. Nevertheless, Fatemi-Socie produced the most accurate results in terms of cracking orientation and Liu II gave the best fatigue life predictions.Financial support of Programa Operativo FEDER from the Junta de Andalucia (Spain) through grant reference UMA18-FEDERJA-250 is greatly acknowledged. Support from the Oceanic Engineering Research Institute from Malaga is also acknowledged. Industrial support from Bettergy and Dr Nicolas Ordo ̃nez is greatly acknowledged, as well as access to different structures and materials in the energy industry. We would also like to acknowledge funding for open access charge: Universidad de Malaga / CBUA

    Time Series of Sentinel-1 Interferometric Coherence and Backscatter for Crop-Type Mapping

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    The potential use of the interferometric coherence measured with Sentinel-1 satellites as input feature for crop classification is explored in this study. A one-year time series of Sentinel-1 images acquired over an agricultural area in Spain, in which 17 crop species are present, is exploited for this purpose. Different options regarding temporal baselines, polarisation, and combination with radiometric data (backscattering coefficient) are analysed. Results show that both radiometric and interferometric features provide notable classification accuracy when used individually (overall accuracy lies between 70% and 80%). It is found that the shortest temporal baseline coherences (6 days) and the use of all available intensity images perform best, hence proving the advantage of the 6-day revisit time provided by the Sentinel-1 constellation with respect to longer revisit times. It is also shown that dual-pol data always provide better classification results than single-pol ones. More importantly, when both coherence and backscattering coefficient are jointly used, a significant increase of accuracy is obtained (greater than 7% in overall accuracy). Individual accuracies of all crop types are increased, and an overall accuracy above 86% is reached. This proves that both features provide complementary information, and that the combination of interferometric and radiometric radar data constitute a solid information source for this application.This work was supported in part by the European Space Agency via the ESA SEOM Program ITT under Grant AO/1-8306/15/I-NB “SEOM-S14SCI Land,” and in part by the Spanish Ministry of Science, Innovation and Universities, the State Agency of Research (AEI), and the European Funds for Regional Development (EFRD) under Project TEC2017-85244-C2-1-P
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