437 research outputs found
¿Cómo abordar la educación del futuro?: conceptualización, desarrollo y evaluación desde la competencia digital docente
La adaptación al cambio en la sociedad del siglo XXI supone un reto en la nueva era digital. En los últimos años la evolución de la tecnología ha transformado el modo en que nos comunicamos o nos desenvolvemos a través de los medios y ha contribuido, consecuentemente, a que la habilidad del individuo progrese para hacer frente a su día a día personal, profesional y académico, siendo capaz de colaborar en equipo, potenciar su participación y desarrollar su creatividad, es decir, poseer una competencia digital. Es lo que conocemos como la «sociedad del conocimiento y de la información».
Actualmente, se puede apreciar de qué modo, en todos los ámbitos –económico, social, cultural y político–, el avance de la tecnología se ha integrado para mejorar su competitividad, y la educación no ha estado exenta de esta evolución. Es en este punto donde este libro plantea, a través de un trabajo de investigación basado en evidencias empíricas, el gran desafío al que se enfrenta la enseñanza, siendo crucial el papel del docente, su formación para el uso de las tecnologías de la información y la comunicación (TIC), su acceso a la tecnología y su posterior implementación.2019-2
Low-pH cement mortar-bentonite perturbations in a small-scale pilot laboratory experiment
This article has been published in a revised form in Clay Minerals [http://doi.org/10.1180/clm.2018.16]. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative worksA novel method to perform small-scale laboratory experiments that reproduce concrete–bentonite and concrete–groundwater interactions has been developed. Such interfaces will prevail in engineered barrier systems used for isolation of nuclear waste. With the goal of optimizing the experimental method, this work has analysed the geochemical interaction of distilled water, low-pH cement mortar and FEBEX-bentonite for 75 days. Limited but evident reactivity between the materials was observed, mainly decalcification in cement mortar, carbonation at the interface with bentonite and Mg enrichment in bentonite. These results are consistent with the state-of-the-art literature and were used to validate this small-scale pilot laboratory experiment to establish the basis for further studies comparing the behaviour of different buffer and cement materialsThe research leading to these results has received funding from the European Union's Horizon 2020 Research and Training
305 Programme of the EURATOM (H2020-NFRP-2014/2015) under grant agreement n° 662147 (CEBAMA
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Perfil psicopatológico de pacientes con Dependencia Emocional
Diversos autores defienden la Dependencia Emocional como una categoría diagnóstica propia. El perfil psicopatológico de las personas afectadas por este trastorno ha sido expuesto a nivel teórico o basado en observaciones clínicas. Con este estudio se pretende determinar el perfil psicopatológico de una muestra de pacientes que presentaban problemas de Dependencia Emocional, desadaptativa, así como estudiar la relación entre autoestima y síntomas psicopatológicos. Se analiza el perfil sintomático a través de los resultados del Symptom CheckList-90 items-Revised (SCL-90-R) y el nivel de autoestima medido a través del Rosenberg Self-Esteem Scale (RSES) de una muestra de 33 pacientes de género femenino admitidos consecutivamente, que consultaron por problemas de dependencia emocional. Las pacientes presentaban elevada puntuación en las escalas obsesión-compulsión, sensibilidad interpersonal, depresión, ansiedad, hostilidad, ideación paranoide, psicoticismo (medidas a través del SCL-90-R) comparados con baremos normativos de población psiquiátrica española y una autoestima baja (medida a través del RSES). En la muestra la autoestima correlaciona de manera negativa con somatización, obsesión-compulsión, depresión y hostilidad. Se discuten las características y perfiles de esta muestra clínica.
English abstract: Several authors defend that Affective Dependence is a diagnostic category. The psychopathological profile of these patients has been explained from a theoretical point of view or based on clinical observations. In that study we want to determinate the pathological profile of a sample of patients with problems of affective dependence, and to study the relationship between their self-esteem and their psychopathological symptoms. We analyzed the symptomatic profile of a sample of 33 female consecutive patients consulting for affective dependence, measured trough the Symptom CheckList-90 items-Revised (SCL-90-R) and the Rosenberg Self-Esteem Scale (RSES). Patients present high obsessive-compulsive, interpersonal sensitivity, depression, anxiety, hostility, paranoid ideation, psychoticism (measured by the SCL- 90-R) compared with compared with normative scores of Spanish psychiatric population, and low self-esteem (measured by the RSES). In these subjects the self- esteem showed negative correlation with somatization, obsessive-compulsive, depression and hostility. These characteristics and profiles are discussed
Frictional power losses on spur gears with tip reliefs. The load sharing role
The load sharing impact on the efficiency of spur gears with modified profile was assessed in this work. The aim was to analyse the influence of the profile modifications on the load sharing, which also considers the effect of the torque level on the system deflections, and how these load sharing variations affected the system efficiency. Due to the frictional effect importance on power losses, in the operating conditions considered, sliding friction between teeth in presence of lubricant was studied in this proposal. The results established that tip relief improves the efficiency of the system due to the reduction of effective contact ratio. Moreover, there is a tip relief which makes optimal the efficiency in specific operating conditions, corresponding to the unit value of the effective contact ratio. Thus, the main conclusion of this work is that the tip relief which makes optimal the efficiency coincides with the theoretical dynamic optimum of the transmission.The authors would like to acknowledge Project DPI 2013-44860 funded by the Spanish Ministry of Science and Technology and the COST ACTION TU 1105 for supporting this research
Analysis of human-induced vibrations in a lightweight framework
This article analyzes the vibratory behavior of a Material-Composed Sandwich (MCS) framework for residential buildings. It has been observed qualitatively that the use of this kind of framework leads to poor comfort levels. The goal of this study is to find out the sources of this lack of comfort, in order to suggest guidelines that can enhance the performance of the MCS framework, without jeopardizing its advantages with respect to the traditional frameworks. To achieve this objective, an Experimental Modal Analysis (EMA) of a sample MCS framework has been carried out in order to determine the dynamic parameters. Then, a numerical Finite Element (FE) model of said sample MCS framework has been developed and adjusted with the results obtained in the experimental test. Based on this, a real-dimension MCS framework FE model has been built and the resultant behavior compared with that of a commonly used framework made of reinforced concrete. This comparison is finally used to assess the uncomfortable dynamic response of the MCS framework and to draw conclusions on the design guidelines in order to enhance the MCS framework vibratory behaviorThe authors would like to acknowledge Project DPI2013-44860 funded by the Spanish Ministry of Science and Technology and COST ACTION TU 1105 for supporting this research
Enhancement of Mechanical Engineering Degree through student design competition as added value. Considerations and viability
This paper proposes using a student design competition as a learning tool in the Mechanical Engineering Degree for enhancing the general competences and motivation of the students, transferring theoretical knowledge to practical situations and bringing together all courses involved under a common framework. This constitutes an added value that the in-person universities should offer to their students as a consequence of the Bologna process and the raising of open online resources for self-learning. In order to assess the viability of this proposal, a pilot competition design activity (CDA) is presented using project-based learning methods during a Mechanism Theory course for sophomore students. Meanwhile, 27 participants of a 45-student course from a European university took part in the pilot CDA, which consisted of redesigning the motorbike rear suspension used in a student design competition. Participants also completed mid-term and final exams as well as a survey to get their perception of this activity. Based on the success of the pilot CDA, the authors are planning to implement the proposal, including similar CDAs in other Mechanical Engineering courses to use the competition as a link between them and to encourage students to participate on the competition.This work [Project DPI2013-44860] was supported by the Spanish Ministry of Science and Technology and Vicerrector Primero y de Profesorado of the University of Cantabria
Frictional power losses on spur gears with tip reliefs. The friction coefficient role
In this proposal, the effect of the friction coefficient on the efficiency of spur gears with tip reliefs was analysed. For this purpose, the efficiency values using an average friction coefficient along the mesh cycle were compared with those obtained implementing an enhanced friction coefficient formulation, which is based on elastohydrodynamic lubrication fundamentals. In this manner, it can be established the differences between both formulations in the efficiency and friction coefficient values, as well as the advantages of using this enhanced friction coefficient with respect to formulations implemented in traditional approaches of efficiency calculation. In addition to studying the impact of the friction coefficient choice on efficiency, the profile modifications influence on the friction coefficient and efficiency was also assessed. In this regard, three tip relief case studies were set out; pinion tip reliefs, driven wheel tip reliefs and profile modifications in both gears. From the results, it was inferred that the choice of friction coefficient formulation clearly influences the efficiency in gear transmissions with tip reliefs, obtaining discrepancies between both formulations with regard to which tip relief case study provides the lowest efficiency values.The authors would like to acknowledge Project DPI 2013-44860 funded by the Spanish Ministry of Science and Technology
Planetary transmission load sharing: Manufacturing errors and system configuration study
This paper addresses the effect of manufacturing errors such as eccentricity and planet pin positioning errors on the quasi-static behavior of a 3 planet planetary transmission, taking into account different configurations regarding the bearing condition of the sun gear shaft. The aim of the paper is to shed light on some untouched aspects of the load sharing behavior of planetary transmissions, such as the effect of radial positioning errors of the planets when different pressure angles are used, and the impact of the different loadings per planet on the actual load per tooth.
A modeling approach is employed, and physical explanations and simplified graphs are provided to help understand the behavior of the transmission when the sun is allowed to float and errors are introduced. The model used, developed by the authors and presented and validated in previous works, hybridizes analytical solutions with finite element models in order to compute the contact forces.
The results obtained show that the teeth loads are much lower than expected compared to the planet uneven loads, both in the non-defected and defected transmission, and that radial positioning errors have non-negligible effect on the load sharing ratio under certain operating conditions.The authors would like to acknowledge Project DPI2013-44860 funded by the Spanish Ministry of Science and Technology for supporting this research
Gear transmission dynamics: Effects of index and run out errors
This work describes a non-linear dynamic model for the study of the vibration signals generated by gear transmissions. The developed model considers both the parametric excitations due to the variable compliance of bearings and gears, can handle changes in the transmitted torque and allows the integration of the dynamic equations quickly and accurately. This model has been developed previously by the authors to assess the profile deviations on the dynamic behavior of gear transmissions and its influence on the transmitted torque. It also includes the presence of gear defects as cracks and pitting during the calculation of meshing forces. In this paper, the model has been enhanced in order to include two common defects such as index errors and run out or eccentricity errors. Index errors occur as a result of a non-uniform angular distribution of the tooth profiles along the pitch circle. Run out appears due to the displacement of the geometric center of the gear with respect to the center of rotation of the shaft on which it is mounted. Although both errors are caused by different reasons, sometimes they have been confused because of their similitudes. The procedure for including both kinds of errors in the model is described and simulations under several transmitted torques are presented. The results are assessed and compared focusing the attention on certain transmission parameters and magnitudes as transmission error, load forces in the tooth flanks and demodulation techniques on the resulting vibratory signals.The authors would like to acknowledge Project DPI2013-44860 funded by the Spanish Ministry of Science and Technology and COST ACTION TU 1105 for supporting this research
Assessment of load dependent friction coefficients and their influence on spur gears efficiency
Traditional procedures to calculate efficiency on gear transmissions generally consider sliding friction as the only dissipative effect, and what is more, they are based on the usage of constant friction coefficients. Although this approach gives acceptable efficiency values depending on the transmission application, the utilisation of a variable friction coefficient provides more reliable results of the friction behavior. Within this framework, the influence of the choice of the friction coefficient on the efficiency of shifted spur gears is assessed in this study. The Niemann?s friction coefficient formulation, which is constant and commonly applied to traditional approaches, was implemented in this proposal, in order to compare it with two hybrid formulations, which are based on elastohydrodynamic lubrication fundamentals and capable to reproduce the friction coefficient in dry contact, boundary, mixed and fluid film conditions of lubrication. These friction coefficient formulations are dependent on the load applied in the conjunction, therefore an enhanced load sharing allows for a better modelling of sliding friction, not only because it depends directly on the normal forces, but due to the friction coefficient load dependence. In this regard, the Load Contact Model previously developed by the authors, which considers the deflections of the adjacent teeth and shifting profile to calculate the load sharing and the friction coefficient, is used, allowing for efficiency values with a high level of accuracy. The efficiency results obtained when hybrid formulations are implemented provides lower values than those determined including Niemann?s formulation. Furthermore, there is a shifting profile which makes optimal the efficiency. This shift factor depends on the implemented friction coefficient formulation, concluding the remarkable importance of the friction coefficient choice.The authors would like to acknowledge Project DPI 2013-44860 funded by the Spanish Ministry of Science and Technology for supporting this research
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