5,228 research outputs found

    Combinaciones litológicas en iglesias románicas de Álava, norte de España

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    Certain windows and doorways on twenty five Romanesque churches of Álava (XII–XIII centuries) were built using six types of rock in nine different combinations. These compositions were intended to highlight the contrast in colour between different rocks, from which it can be deduced that the openings were not hewn to be painted. After almost seven centuries during which the use of stone was anecdotal, Romanesque artists burst in with colourful blends, demonstrating a broad knowledge of the characteristics of each rock and its availability. The uniqueness of these openings is represented on lithologic maps which, in addition to facilitating its analysis and dissemination, serve as a reference in its restoration.Algunas ventanas y portadas de veinticinco iglesias románicas de Álava (siglos XII-XIII) fueron construidas con hasta seis tipos de rocas en nueve combinaciones diferentes. Estas composiciones pretendían resaltar el contraste cromático entre rocas distintas, de lo que se deduce que los vanos no fueron tallados para ser policromados. Después de casi siete siglos en los que el uso de la piedra fuera anecdótico, los artistas románicos irrumpen con mezclas coloristas, mostrando un amplio conocimiento de las características de cada roca y su disponibilidad. La singularidad de estos vanos está representada en mapas litológicos que, además de facilitar su análisis y divulgación, servirán de referencia en su restauració

    Análisis de lineamientos detectados por sensores remotos sobre imágenes landsat: la influencia del factor humano y su relevancia en estudios tectónicos o de investigación minera

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    [Abstract] In the present work we deal with the influence of the so-called «human component » on lineament photointerpretation and LANDSAT images. The statistical study of the lineaments drawn by three different analysts on the same LANDSTAT image is performed, being the tested a geologically well-known portion of the Iberian Hercynian Mássif: the Badajoz-C6rdoba Shear Zone. The results obtained let us consider attentively the role played by the analyst subjectivity on the finallineament networks. As a result, the consequence of the studies of this type on mineral exploration and tectonics are discussed, being undeniable the validity of this technique.[Resumen] En este trabajo se estudia la influe'ncia del que se ha dado en denominar «componente humano» en la fotointerpretación de lineamentos estructurales sobre imágenes LANDSAT. Se realiza un estudio estadístico de las fotolíneas dibujadas sobre un mismo soporte fotográfico por tres analistas diferentes. El área uálizada para la realización de la prueba es el Corredor Blastomilonítico de Badajoz Córdoba, una región relativamente bien conocida del Macizo Ibérico. Los resultados y conclusiones alcanzados permiten efectuar una estimación semicuantitativa del papel jugado por la subjetividad del analista sobre las redes de fotolíneas obtenidas. Las principales consecuencias que se derivan de este estudio son discutidas desde la perspectiva de la tectónica y de la exploración mineral, resaltando la validez de la técnica de teledetección utilizada

    User innovations through online communities from the perspective of social network analysis

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    Organizations have begun to leverage both internal and external sources for innovation. Specifically, organizations are increasingly relying on end users that engage via user innovation communities to identify potentially valuable ideas for an organization to adopt. However, research has shown that organizational success in leveraging these communities relies on a thorough understanding of how users behave within the community. The purpose of this manuscript is to provide further analysis and develop a richer understanding of user behavior in the Dell IdeaStorm user innovation community. Findings illustrate different patterns of user behaviors when they comments or rate posted idea

    A technological acceptance of e-learning tools used in practical and laboratory teaching, according to the European higher education area

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    The application of scientific tools to analyse the use of Internet-based e-learning tools in academic settings is in general an ignored area. E-learning tools are actually an emergent topic as a result of the new ideas introduced by the European Higher Education Area. Lifelong learning, or the promotion of student initiative, is the new paradigm of a learner-centred education. In this context, e-learning tools can represent an effective way of supporting this new trend in education. Assuming the premise that successful use of these web-based tools depends primarily on a user’s behaviour, the objective of this research is to examine the technology acceptance model (TAM) of web-based elearning tools used in practical and laboratory teaching. The research hypotheses derived from this model have empirically been validated using the responses to a survey on e-learning usage among 220 users. These responses have been examined through partial least square. The obtained results strongly support the extended TAM in predicting a student’s intention to use e-learning and define a set of external variables with a significant influence in the original TAM variables. Surprisingly, perceived ease of use did not posit a significant impact on student attitude or intention towards e-learning tool usage. Therefore, early evaluation of e-learning material is considered essential to providing a framework for further improvements of the too

    X(2175) as a resonant state of the ϕKKˉ\phi K \bar{K} system

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    We perform a Faddeev calculation for the three mesons system, ϕKKˉ\phi K \bar{K}, taking the interaction between two pseudoscalar mesons and between a vector and a pseudoscalar meson from the chiral unitary approach. We obtain a neat resonance peak around a total mass of 2150 MeV and an invariant mass for the KKˉK \bar{K} system around 970 MeV, very close to the f0(980)f_0(980) mass. The state appears in I=0 and qualifies as a ϕf0(980)\phi f_0(980) resonance. We enlarge the space of states including ϕππ\phi \pi \pi, since ππ\pi \pi and KKˉK \bar{K} build up the f0f_0 (980), and find moderate changes that serve to quantify theoretical uncertainties. No state is seen in I=1. This finding provides a natural explanation for the recent state found at BABAR and BES, the X(2175), which decays into ϕf0(980)\phi f_0(980).Comment: version accepted for publicatio

    Modelo analítico para el transporte electrónico en películas delgadas semiconductoras

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    Polycrystalline semiconductors are materials who often exhibit unusual electrical properties. In the model we assume that the crystals are composed of semiconductor material, the grain itself, which is surrounded by highly disordered and resistive materials, the grain boundary. The grain boundary disturbs the structural regularity of the crystal giving rise to localized electronic states within the energy gap. The existence of these states promotes the charge trapping at the grain boundaries and the bending of the energy bands. This bending is characterized by a potential barrier and a space charge zone which control the electron transport through the grain boundary. The model uses the diusion and drift carriers theories, and thermoionic emission, and the quantum tunneling of carriers through the potential barrier was also taken into consideration. Since the structure of the thin lms of molybdenum trioxide (MoO3) obtained through spray pyrolysis is granular and nanosize, the model described the behavior of the current-voltage characteristic (I-V) of the films.Los semiconductores policristalinos son materiales que a menudo exhiben propiedades eléctricas inusuales. En el modelo suponemos que los cristales están compuestos de material semiconductor, el grano mismo, que está rodeado de materiales altamente desordenados y resistentes, el límite del grano. El límite de grano perturba la regularidad estructural del cristal, dando lugar a estados electrónicos localizados dentro de la brecha de energía. La existencia de estos estados promueve la captura de carga en los límites del grano y la flexión de las bandas de energía. Esta flexión se caracteriza por una barrera potencial y una zona de carga espacial que controlan el transporte de electrones a través del límite del grano. El modelo utiliza las teorías de los portadores de deriva y deriva, y la emisión termoiónica, y también se tuvo en cuenta el túnel cuántico de los portadores a través de la barrera potencial. Dado que la estructura de las películas finas de trióxido de molibdeno (MoO3) obtenidas a través de la pirólisis por pulverización es granular y de tamaño nanométrico, el modelo describió el comportamiento de la característica de corriente-voltaje (I-V) de las películas

    Design of graphene-based TiO2 photocatalysts - A review

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    There is a recent increase in the interest of de- signing high-performance photocatalysts using graphene- based materials. This review gathers some important aspects of graphene–TiO 2 , graphene oxide–TiO 2 , and reduced gra- phene oxide–TiO 2 composites, which are of especial rele- vance as next generation photocatalysts. The methods used for the preparation of these materials, the associated mech- anistic fundamentals, and the application of graphene-based composites on the photocatalytic degradation of pollutants are reviewed. Some structural, textural, and chemical prop- erties of these materials and other photo-assisted applica- tions, such as hydrogen production from water splitting and dye-sensitized solar cells, are also briefly includedFinancial support for this work was provided by the European Commission (Clean Water—grant agreement no 227017) and by Fundação para a Ciência e a Tecnologia (FCT) and FEDER under Program COMPETE, project FCOMP-01-0124-FEDER-022706 (Ref. FCT Pest-C/EQB/LA0020/2011) and FCOMP-01-0124-FEDER- 008442 (Ref. NANO/NTec-CA/0046/2007). Clean Water is a Collab- orative Project co-funded by the Research DG of the European Com- mission within the joint RTD activities of the Environment and NMP Thematic Priorities. SMT and AMTS acknowledge financial support from SFRH/BPD/74239/2010 and POCI/N010/2006, respectively

    Addressing learner satisfaction outcomes in electronic instrumentation and measurement laboratory course organization

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    This paper proposes and details a course organization methodology based on learner satisfaction achievement. The approach follows the prevailing tendency in modern university reforms which are primarily concerned about “how people learn.” As a consequence, the learner has been placed as the main actor of the teaching–learning process. Nevertheless, the current learning literature has not addressed the measurement of learner satisfaction within laboratory and practical subjects. This study develops a general and comprehensive methodology for learner satisfaction measurement in practical subjects. As a case example, the proposed methodology has been applied to an electronic instrumentation and measurement course, confirming the variables with a significant influence on learner satisfaction and becoming the starting point for curriculum redesign based on the learner satisfaction approach. To assess the improvement of the proposed course organization methodology, a comparison with previous academic years has been performed showing the students’ rated score evolution. Results fully confirm the validity of the technique and the novel course organizatio

    An electronic engineering curriculum design based on concept-mapping techniques

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    Curriculum design is a concern in European Universities as they face the forthcoming European Higher Education Area (EHEA). This process can be eased by the use of scientific tools such as Concept-Mapping Techniques (CMT) that extract and organize the most relevant information from experts’ experience using statistics techniques, and helps a working group to achieve conclusions. This paper presents an empirical exploratory research study related to the application of the CMT to the design of the Electronic Engineering (EE) Degree at the University of Seville, Spain. Considering the Career-space conclusions as the initial point, the main relevant competences were identified in a brainstorming technique. These competences are organized according to their affinity using CMT, establishing and interpreting the main clusters and their relative importance. Finally, a reliability analysis of the concept maps was carried out verifying the correctness of the procedure and validating the results for the curricula adaptatio
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