750 research outputs found
Validation of the competences for the 21st century skill scale in higher education students
In a global society, the importance of knowledge and assessment of transversal competences emerges to cope with the challenges of contemporary society, from a perspective of development and lifelong learning. Therefore, it is a priority to use assessment tools adapted to different cultures. The main objective of this study is to validate the instrument ‘Multidimensional 21st Century Skills Scale’ for the Portuguese population. The sample was composed of 413 participants of both genders, with a mean age of 24.30 years (standard deviation = 8.69), aged between 18 and 64 years, attending Higher and Vocational Education. The translation and back-translation of the instrument were carried out by experts (researchers and university professors in the areas of psychology, management, and entrepreneurship). The final version of the scale was composed of 30 items and the exploratory analysis identified three dimensions: Knowledge and Entrepreneurial Skills, Career Awareness and Innovation, and Critical Thinking and Problem Solving. These factors were validated by confirmatory analysis. The authors suggest that the difference found in relation to the original version is related to cultural reasons, the age range of the respondents, as well as their academic levelinfo:eu-repo/semantics/publishedVersio
Rammed Earth Construction: A Proposal for a Statistical Quality Control in the Execution Process
Unlike other common contemporary construction materials such as concrete, mortars,
or fired clay bricks, which are widely supported by international standards and regulations,
building with rammed earth is barely regulated. Furthermore, its quality control is usually problematic,
which regularly encourages the rejection of this technique. In the literature, many authors have
suggested ways to safely build a rammed earth wall, but only a few of them have delved into its
quality control before and during the construction process. This paper introduces a preliminary
methodology and establishes unified criteria, based in a statistical analysis, for both the production
and the quality control of this constructive technique in cases dealing with both samples and walls
Morphology of copper deposits obtained by metallic electrodeposition
Electrochemical deposition of copper from copper nitrate aqueous electrolyte on graphite substrate was investigated at current densities between 0.03 mA/cm2 - 1.36 mA/cm2 and in the voltage range of 3 V to 15 V. The surface morphology and elemental composition of the resultant deposit were characterized by electron microprobe analysis (EMPA). These images illustrate the influence of current density on the shape of copper electrodeposited on the electrode surface. Rods, polyhedral bodies, pentagonal pyramids, dendritics, spiked spheres or cauliflower-like shapes are observed depending on the electrodeposition conditions.Fil: González Mercado, Griselda Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Gonzalez, Carlos Jacinto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; ArgentinaFil: Oliva, Marcos Iván. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; ArgentinaFil: Brunetti, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Eimer, Griselda Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigación y Tecnología Química. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación y Tecnología Química; Argentin
A Produção, Difusão e Recepção de Conteúdos Telejornalísticos na Era da Convergência Digital
Neste artigo, tendo por base uma revisão bibliográfica, são expostas algumas apreciações acerca da produção, difusão e recepção de conteúdos informativos televisivos na era da convergência digital, procurando assinalar e analisar as principais transformações nestes campos. Na era da convergência digital, os processos de conceção, distribuição e consumo de conteúdos jornalísticos transmitidos através da televisão estão a ser redefinidos.UD
Adaptive Comfort Models Applied to Existing Dwellings in Mediterranean Climate Considering Global Warming
Comfort analysis of existing naturally ventilated buildings located in mild climates, such
as the ones in the Mediterranean zones, offer room for a reduction in the present and future energy
consumption. Regarding Spain, most of the present building stock was built before energy standards
were mandatory, let alone considerations about global warming or adaptive comfort. In this context,
this research aims at assessing adaptive thermal comfort of inhabitants of extant apartments building
in the South of Spain per EN 15251:2007 and ASHRAE 55-2013. The case study is statistically
representative housing built in 1973. On-site monitoring of comfort conditions and computer
simulations for present conditions have been carried out, clarifying the degree of adaptive comfort
at present time. After that, additional simulations for 2020, 2050, and 2080 are performed to check
whether this dwelling will be able to provide comfort considering a change in climate conditions.
As a result, the study concludes that levels of adaptive comfort can be considered satisfactory at
present time in these dwellings, but not in the future, when discomfort associated with hot conditions
will be recurrent. These results provide a hint to foresee how extant dwellings, and also dwellers,
should adapt to a change in environmental conditions
Os fatores que contribuem para que os jornalistas da redação central da SIC editem em vídeo conteúdos informativos
No âmbito do programa doutoral em Informação e Comunicação em Plataformas
Digitais das Universidades de Aveiro e Porto, foi desenvolvida uma tese de doutoramento
com o título «O Binómio Jornalistas-Editor de Imagem na Produção Noticiosa
Televisiva: causas e consequências». Neste artigo apresentam-se e discutem-se os
fatores que contribuem para que os jornalistas da redação central da SIC editem em
vídeo conteúdos informativos
Thermo-Hydro-Mechanical Behaviour of expansive clays under high temperatures
Esta Tesis presenta los resultados de la investigación desarrollada en el marco del proyecto Temperature Buffer Test (TBT). El objetivo general de este proyecto es investigar el desempeño de la bentonita usada en barreras de ingeniería bajo la acción de las altas temperaturas que se esperan alrededor de los contenedores con residuos vitrificados. Dentro del proyecto, se ha implementado un ensayo de campo a escala real que simula el almacenamiento de residuos radioactivos de alta actividad. Adicionalmente, se realizaron experimentos en laboratorio para evaluar la respuesta de la bentonita usada en el proyecto bajo diferentes acciones externas.Las formulaciones que se usan para analizar el comportamiento de barreras de ingeniería de arcillas se escriben en términos de las variables de estado usando relaciones constitutivas. Entre esas leyes la curva de retención define la relación constitutiva entre la cantidad de agua en el suelo y su nivel de energía. Tradicionalmente, la influencia de variables externas como la temperatura y la fábrica del suelo sobre la capacidad de retención de agua del suelo se analiza utilizando conceptos derivados del modelo capilar. Sin embargo, estos análisis sistemáticamente fallaron para explicar las observaciones experimentales. En esta Tesis, se han evaluado los datos experimentales obtenidos en muestras de bentonita ensayadas a diferentes temperaturas y densidades usando una aproximación derivada a partir de conceptos de termodinámica de adsorción. Esta aproximación también define una herramienta para introducir en una manera simple el efecto de temperatura y densidad de la muestra en las simulaciones numéricas.En general se supone que la interacción entre la esmectita, que es el principal mineral de la bentonita, y el agua cambia las propiedades del agua retenida en el suelo. En particular, experimentos a nivel mineralógico así como los datos obtenidos en muestras compactadas de arcilla expansiva sugieren valores de la densidad del agua mayores que 1.0 Mg/m3 (es decir, la densidad del agua libre). Desde un punto de vista práctico, este efecto se traduce en valores calculados del grado de saturación mayor que uno para valores bajos de succión. Este aspecto es importante cuando se realizan análisis numéricos, debido a que las ecuaciones de balance se basan en el grado de saturación como la principal variable para indicar el contenido de agua en el medio poroso. En esta Tesis se ha desarrollado una metodología que define la densidad del agua como una función de la energía del agua en los poros del suelo. Este método fue usado para analizar datos publicados de la capacidad de retención de agua de muestras compactadas de diferentes bentonitas.El análisis de la respuesta mecánica de arcillas expansivas bajo acciones externas como aquellas típicamente encontradas en barreras de ingeniería es una tarea compleja. Los modelos constitutivos usados en los cálculos numéricos deben ser capaces de simular los principales aspectos de la respuesta material. En esta Tesis se han adoptado modelos previamente desarrollados para simular el comportamiento de muestras compactadas de arcilla expansiva. Los parámetros de estos modelos se calibraron usando datos experimentales que corresponden a muestras compactadas de bentonita MX-80, el material adoptado como referencia en el proyecto TBT.Los conceptos desarrollados en esta Tesis se incorporaron en un código numérico capaz de resolver problemas acoplados en medios porosos deformables. Este código fue aplicado tanto para el análisis de un ensayo de maqueta como para la simulación del ensayo in situ, ambos desarrollados en el marco del proyecto TBT. Las simulaciones numéricas demostraron las capacidades del código para capturar la tendencia general de los datos experimentales. Además, el análisis de los resultados numéricos puso de manifiesto los diferentes fenómenos que tienen lugar en los procesos acoplados así como los mecanismos de interacción entre ellos.This Thesis presents the results of the research carried out in the framework of the Temperature Buffer Test (TBT) project. The overall objective of this project is to investigate how well the bentonite used in engineered barriers can endure the high temperatures expected to be found around vitrified waste canisters. Within the project, a full-scale field test that simulates the deposition of high level radioactive waste has been implemented. Additionally, laboratory experiments were carried out to evaluate the response of the bentonite used in the project under different external actions.Coupled formulations used to analyse the behaviour of an engineered clay barrier are written in terms of the state variables by using constitutive relations. Among these laws the soil water retention curve (SWRC) defines the constitutive relationship between the amount of water in the soil and its energy status. Traditionally, the influence of external variables like temperature and soil fabric on the water retention capacity of soils has been analysed using concepts derived from the capillary model. However, theses analyses systematically failed to explain the experimental observations. In this Thesis, experimental data obtained on bentonite samples tested at different temperatures and densities were evaluated using an approach derived from concepts of thermodynamic of adsorption. This approach also gives a tool to introduce in a simple way the effect of temperature and sample porosity in numerical simulations.It is generally accepted that the interaction between smectite, which is the main mineral of bentonite, and water changes the properties of the water retained in the soil. In particular, values of the water density higher than 1.0 Mg/m3 (i.e. the density of the free water) have been suggested by experiments at mineralogical level as well as by data obtained on compacted samples of expansive clays. From a practical point of view this effect traduces in values of degree of saturation higher than one at lower values of suction. This is important when a numerical analysis is being performed, as balance equations are based on the degree of saturation as the main variable to indicate the water content within the porous medium. In this Thesis a methodology that defines the water density as a function of the energy of the water within the soil pores was developed. This method was applied to analyse published data about the water retention capacity for compacted samples of different bentonites.The analysis of the mechanical response of expansive clays under external actions as those typically found in engineered barriers is a complex task. Constitutive models used in numerical calculations have to be able to simulate the main aspects of the material response. Models previously developed to simulate the behaviour of compacted samples made up of expansive clay were adopted in this Thesis. Parameters in these models were calibrated using experimental data corresponding to compacted samples of MX-80 bentonite, the material adopted as reference in the TBT project.Concepts developed in the Thesis were included in a numerical code able to solve coupled problems in deformable porous media. This code was then applied to the analysis of a mock-up experiment and to the simulation of the in situ test carried out within the framework of the TBT project. Theses numerical simulations showed the capabilities of the code to capture the general tendency of the experimental data. Additionally, the analysis of numerical results enhanced the understanding of the different phenomena that take place in coupled processes as well as the interaction mechanisms between them
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