2,434 research outputs found

    Transient Propagation and Scattering of Quasi-Rayleigh Waves in Plates: Quantitative comparison between Pulsed TV-Holography Measurements and FC(Gram) elastodynamic simulations

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    We study the scattering of transient, high-frequency, narrow-band quasi-Rayleigh elastic waves by through-thickness holes in aluminum plates, in the framework of ultrasonic nondestructive testing (NDT) based on full-field optical detection. Sequences of the instantaneous two-dimensional (2-D) out-of-plane displacement scattering maps are measured with a self-developed PTVH system. The corresponding simulated sequences are obtained by means of an FC(Gram) elastodynamic solver introduced recently, which implements a full three-dimensional (3D) vector formulation of the direct linear-elasticity scattering problem. A detailed quantitative comparison between these experimental and numerical sequences, which is presented here for the first time, shows very good agreement both in the amplitude and the phase of the acoustic field in the forward, lateral and backscattering areas. It is thus suggested that the combination of the PTVH system and the FC(Gram) elastodynamic solver provides an effective ultrasonic inspection tool for plate-like structures, with a significant potential for ultrasonic NDT applications.Comment: 46 pages, 16 figures, corresponding author Jos\'e Carlos L\'opez-V\'azquez, [email protected]. Changes: 1st, 4th, 5th paragraphs (intro), 3rd, 4th paragraphs (sec. 4); [59-60] cited only in appendixes; old ref. [52] removed; misprints corrected in the uncertainty of c_L (subsec. 3.1), citation to fig. 10 (sec. 4), size of images (caption fig.15); reference to Lam\'e constants removed in subsec. 3.

    Propuesta de itinerario interdisciplinar en la formación del profesorado de Educación Primaria en el ámbito de las Ciencias Sociales y Experimentales

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    Proponemos en este trabajo un planteamiento interdisciplinar cuya experiencia se está llevando a cabo en la Facultad de Ciencias de la Educación de la Universidad de Córdoba, entre las áreas de Didáctica de las Ciencias Sociales y Experimentales, a través de una metodología activa en el desarrollo de un itinerario didáctico, donde el alumnado es el que lleva a cabo la preparación de las paradas y la exposición de las mismas. Esta propuesta de colaboración entre estas dos áreas fija sus objetivos en la participación integral de cada discente a través de la búsqueda y análisis de información relevante y la cooperación entre grupos. La tarea fomenta capacidades y competencias relacionadas con la transversalidad y la interdisciplinariedad de los contenidos y para su formación en el Grado de Educación Primaria.The aim of this work is to develop an educational itinerary to describe an interdisciplinary proposal that it is being developed in the Bachelor Degree of Primary Education belonging to the Faculty of Education Sciences in the University of Córdoba, with the implication of two areas of knowledge: Didactics of Social Sciences and Didactics of Experimental Sciences. We implemented an educational itinerary through the city of Cordoba, in which the students had to prepare and explain several aspects of the different points of interest in the itinerary, regarding with Social and/or Experimental Sciences. This activity implies an active and participative methodology that allows the students to develop some competencies as cooperative work, searching for information or oral presentations. Furthermore, this also promotes both interdisciplinarity and transversality. The main objective of this activity is to make the students reflect on the importance of their surroundings and on the possibilities that Cordoba city offers to be used as an educational resource

    A Review on Intelligent Monitoring and Activity Interpretation

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    A strike-slip fault corridor within the Alpujarra Mountains (Betic Cordilleras, Spain)

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    15 páginas, 6 figuras.[EN] In a long »corridor« in the internal zone of the Betic Cordilleras, bounded to the north by the Sierra Nevada and to the south by the Sierras Lujar, Contraviesa and Gador, two discernible bands of strike-slip faults exist: These bands lie in an approximately E-W direction and are well exposed throughout and beyond the 85 km long belt. The characteristic features of strike-slip faults, such as cataclastic rocks composed of variously textured fault breccia, which also include fragments of rocks up to several metres in size, incipient foliation, and striation demonstrate the right-lateral nature of the displacement. There are also fractures which run in a NW-SE and NNE-SSW direction, and apparently originated after formation of the E-W faults. The magnitude of lateral displacements is difficult to calculate. Evidence of considerable vertical movement can be found locally. These strike-slip displacements have essentially occurred since the middle Miocene period and might still be taking place.[AL] In einem langen Korridor in der Internzone der Betischen Kordilleren, der im Norden durch die Sierra Nevada und im Süden von den Sierren Lujar, Contraviesa und Gador begrenzt wird, sind zwei Streifen mit Blattverschiebungen zu beobachten. Sie streichen etwa E-W und sind gut entlang des 85-km-langen Gürtels aufgeschlossen. Die charakteristischen Merkmale von Blattverschiebungen wie etwa kataklastische Gesteine mit verschiedenen texturierten Verwerfungsbrekzien, welche auch bis zu mehreren Metern große Gesteinsblöcke enthalten, beginnende Schieferung und Harnischbildung, zeigen die dextrale Natur der Bewegung. Daneben treten NW-SE und NNE-SSW streichende Störungen auf, die offensichtlich nach der Bildung der E-W verlaufenden Blattverschiebungen entstanden sind. Das Ausmaß des lateralen Versatzes ist schwer abzuschätzen. Diese Bewegungen finden seit dem mittleren Miozän statt und sind möglicherweise immer noch aktiv.[FR] Dans un long couloir situé dans la zone interne des Chaînes Bétiques et limité au Nord par la Sierra Névada et au Sud par les Sierras de Lujar, Contraviesa et Gador, s'observent deux trains de failles de décrochements. Ces trains ont une direction à peu près E-W et sont bien exposés tout au long des 85 Km de cette zone. Les traits caractéristiques des décrochements, tels que cataclasites, brèche de faille avec fragments de roches jusqu'à plusieurs mètres de longueur, schistosité naissante et striation, démontrent la nature dextre du déplacement. Il existe aussi des fractures de direction NW-SE et NNW-SSW qui se sont vraisemblablement formées postérieurement aux failles E-W. La valeur du déplacement latéral est difficile à estimer. On rèléve localement des indices de mouvements verticaux importants. Ces décrochements se sont produits essentiellement à partir du Miocène moyen et peuvent encore se poursuivre aujourd'hui.This study was carried out under the auspices of the Departamento de Investigaciones Geológicas del C.S.I.C., Centro Coordinado con la Universidad de Granada, during a research project entitled: "Borde mediterráneo español: Evolución del Orógeno Bético y Geodinámica de las Depresiones Neógenas".Peer reviewe

    Recursos materials per al desenvolupament motor gros en escolars de 6-9 anys

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    L’objectiu de la recerca ha estat conèixer els recursos materials d’educació física més eficaços per millorar el desenvolupament motor gros de l’alumnat de 6 a 9 anys, en funció del seu sexe i edat. La mostra de 982 escolars es va dividir en tres grups experimentals segons el tipus de material fungible i un grup de control. Es va emprar el test TGM-2, mitjançant un pretest i un postest després d’una intervenció de 14 sessions. La diferència de puntuacions directes en els dos àmbits (locomotriu i control d’objectes) va ser major en els grups experimentals (p-valor<0,05). Aquesta diferència resulta més elevada amb l’ús de materials alternatius, seguit de només pilotes i sense pilotes en tots dos cicles educatius i en els dos sexes, excepte per a les nenes de segon cicle, on els millors resultats es produeixen en el grup experimental de materials només pilotes

    Recursos materiales para el desarrollo motor grueso en escolares de 6-9 años

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    El objetivo de la investigación ha sido conocer los recursos materiales de educación física más eficaces para mejorar el desarrollo motor grueso del alumnado de 6 a 9 años, en función de su sexo y edad. La muestra de 982 escolares estuvo dividida en tres grupos experimentales según el tipo de material fungible y un grupo de control. Se empleó el test TGM-2, mediante un pretest y un postest tras una intervención de 14 sesiones. La diferencia de puntuaciones directas en los dos ámbitos (locomotor y control de objetos) fue mayor en los grupos experimentales (p-valor<0,05). Dicha diferencia resulta más elevada con el uso de materiales alternativos, seguido de “solo balones” y “no balones” en ambos ciclos educativos y en los dos sexos, excepto para las niñas de segundo ciclo, donde los mejores resultados se producen en el grupo experimental de materiales “solo balones”

    Hazards of swine slurry: Heavy metals, bacteriology, and overdosing—Physicochemical models to predict the nutrient value

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    In this work, 124 samples of slurry from 32 commercial farms of three animal categories (lactating sows, nursery piglets, and growing pigs) were studied. The samples were collected in summer and winter over two consecutive years and analyzed for physicochemical properties, macronutrient and micronutrient, heavy metals, and major microbiological indicators. The results were found to be influenced by farm type and to deviate especially markedly in nursery piglets, probably as a consequence of differences in pig age, diet, and management. The main potential hazards of the slurries can be expected to arise from their high contents in heavy metals (Cu and Zn), especially in the nursery piglet group, and from the high proportion of samples testing positive for Salmonella spp. (66%). Linear and nonlinear predictive equations were developed for each animal category and the three as a whole. Dry matter, which was highly correlated with N, CaO, and MgO contents, proved the best predictor of fertilizer value. Using an additional predictor failed to improve the results but nonlinear and farm-specific equations did. Rapid on-site measurements can improve the accuracy of fertilizer value estimates and help optimize the use of swine slurry as a resultThis work was supported by the Xunta de Galicia (Unidad Mixta de Investigacion, Desarrollo e Innovacion sobre el Sector Cárnico) and by the pre-doctoral grant of Miguel Fernández-Labrada from “Programa de ayudas a la etapa predoctoral” of the Xunta de Galicia (Consellería de Educacion, Universidade e Formacion Profesional) (grant number ED481A-2020/130)S

    AMISEC: Leveraging Redundancy and Adaptability to Secure AmI Applications

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    Security in Ambient Intelligence (AmI) poses too many challenges due to the inherently insecure nature of wireless sensor nodes. However, there are two characteristics of these environments that can be used effectively to prevent, detect, and confine attacks: redundancy and continuous adaptation. In this article we propose a global strategy and a system architecture to cope with security issues in AmI applications at different levels. Unlike in previous approaches, we assume an individual wireless node is vulnerable. We present an agent-based architecture with supporting services that is proven to be adequate to detect and confine common attacks. Decisions at different levels are supported by a trust-based framework with good and bad reputation feedback while maintaining resistance to bad-mouthing attacks. We also propose a set of services that can be used to handle identification, authentication, and authorization in intelligent ambients. The resulting approach takes into account practical issues, such as resource limitation, bandwidth optimization, and scalability
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