238 resultados para racines fines


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The main objectives and findings of this first research report are presented in this chapter."The Implementation of the Internet in the Spanish Education System: State of Affairs and Future Prospects" is a large-scale research project that seeks to obtain relevant data about the introduction and dissemination of Information and Communication Technology, particularly the internet, in the practical and organizational general procedures of the Spanish schools and high schools. The project articulates the processes of ICT implementation on the primary and secondary education levels embracing a holistic approach, propped up by an empirical and analytical research methodology. Thus, our survey does not intend to detect which is the impact of ICT on school activities but how all the agents involved in the school community incorporate ICT and what use they make of it. We are especially interested in identifying the teachers' pedagogical and professional uses of ICT, how students use it in their activities and to what extent it contributes in reinforcing teamwork and participation proceedings in the institutions, as well as the relations between the latter and their context. It is also of our interest to know the factors that exert the strongest influence on the way teachers, head teachers and students make use of ICT. Finally, we intend to identify the ways ICT may contribute to the improvementof educational practices.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The degradation of the catalytic filaments is the main factor limiting the industrial implementation of the hot wire chemical vapor deposition (HWCVD) technique. Up to now, no solution has been found to protect the catalytic filaments used in HWCVD without compromising their catalytic activity. Probably, the definitive solution relies on the automatic replacement of the catalytic filaments. In this work, the results of the validation tests of a new apparatus for the automatic replacement of the catalytic filaments are reported. The functionalities of the different parts have been validated using a 0.2 mm diameter tungsten filament under uc-Si:H deposition conditions.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The degradation of the filaments is usually studied by checking the silicidation or carbonization status of the refractory metal used as catalysts, and their effects on the structural stability of the filaments. In this paper, it will be shown that the catalytic stability of a filament heated at high temperature is much shorter than its structural lifetime. The electrical resistance of a thin tungsten filament and the deposition rate of the deposited thin film have been monitored during the filament aging. It has been found that the deposition rate drops drastically once the quantity of dissolved silicon in the tungsten reaches the solubility limit and the silicides start precipitating. This manuscript concludes that the catalytic stability is only guaranteed for a short time and that for sufficiently thick filaments it does not depend on the filament radius.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The singular properties of hydrogenated amorphous carbon (a-C:H) thin filmsdeposited by pulsed DC plasma enhanced chemical vapor deposition (PECVD), such as hardness and wear resistance, make it suitable as protective coating with low surface energy for self-assembly applications. In this paper, we designed fluorine-containing a-C:H (a-C:H:F) nanostructured surfaces and we characterized them for self-assembly applications. Sub-micron patterns were generated on silicon through laser lithography while contact angle measurements, nanotribometer, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the surface. a-C:H:F properties on lithographied surfaces such as hydrophobicity and friction were improved with the proper relative quantity of CH4 and CHF3 during deposition, resulting in ultrahydrophobic samples and low friction coefficients. Furthermore, these properties were enhanced along the direction of the lithographypatterns (in-plane anisotropy). Finally, self-assembly properties were tested with silicananoparticles, which were successfully assembled in linear arrays following the generated patterns. Among the main applications, these surfaces could be suitable as particle filter selector and cell colony substrate.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Electron scattering on a thin layer where the potential depends self-consistently on the wave function has been studied. When the amplitude of the incident wave exceeds a certain threshold, a soliton-shaped brightening (darkening) appears on the layer causing diffraction of the wave. Thus the spontaneously formed transverse pattern can be viewed as a self-induced nonlinear quantum screen. Attractive or repulsive nonlinearities result in different phase shifts of the wave function on the screen, which give rise to quite different diffraction patterns. Among others, the nonlinearity can cause self-focusing of the incident wave into a beam, splitting in two "beams," single or double traces with suppressed reflection or transmission, etc.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dados ciertos cambios en el ámbito socio político como la globalización, el incremento de la movilidad y las características de la emigración, y en el ámbito educativo europeo, como el proceso de Bologna y el apoyo por parte de las instituciones europeas a los programas de intercambio, el aula de la educación terciaria se está convirtiendo cada vez más en un espacio heterogéneo. Hasta ahora los académicos han esperado y dado por hecho que los estudiantes se adapten a su método y concepto de enseñanza, este naturalmente impregnado por su paradigma cultural, sin tener en consideración diferencias en estilos de aprendizaje, cultura, valores y normas; en otras palabras se ha asumido una enseñanza centrada en el profesor como la única válida y viable. En opinión de las autoras esta actitud no corresponde con la tan proclamada internacionalización de la educación sino más bien con una perspectiva etnocéntrica y desfasada por parte del profesorado. Este artículo postula contemplar al estudiante como un cliente (“personalización de la educación”) y por consiguiente adaptar el estilo docente a la nueva realidad internacional universitaria con dos claros fines: mantener y/o mejorar la excelencia académica y satisfacer al cliente, al estudiante. En la última parte del artículo se proponen innovativos enfoques en la enseñanza que pueden respaldar al profesorado en su tarea de tratar con un alumnado cada vez más diverso

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The main objective of this research was to study the feasibility of incorporating organosolv semi-chemical triticale fibers as the reinforcing element in recycled high density polyethylene (HDPE). In the first step, triticale fibers were characterized in terms of chemical composition and compared with other biomass species (wheat, rye, softwood, and hardwood). Then, organosolv semi-chemical triticale fibers were prepared by the ethanolamine process. These fibers were characterized in terms of its yield, kappa number, fiber length/diameter ratio, fines, and viscosity; the obtained results were compared with those of eucalypt kraft pulp. In the second step, the prepared fibers were examined as a reinforcing element for recycled HDPE composites. Coupled and non-coupled HDPE composites were prepared and tested for tensile properties. Results showed that with the addition of the coupling agent maleated polyethylene (MAPE), the tensile properties of composites were significantly improved, as compared to non-coupled samples and the plain matrix. Furthermore, the influence of MAPE on the interfacial shear strength (IFSS) was studied. The contributions of both fibers and matrix to the composite strength were also studied. This was possible by the use of a numerical iterative method based on the Bowyer-Bader and Kelly-Tyson equations

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The process of hydrogen desorption from amorphous silicon (ɑ-Si) nanoparticles grown by plasmaenhanced chemical vapor deposition (PECVD) has been analyzed by differential scanning calorimetry (DSC), mass spectrometry, and infrared spectroscopy, with the aim of quantifying the energy exchanged. Two exothermic peaks centered at 330 and 410 °C have been detected with energies per H atom of about 50 meV. This value has been compared with the results of theoretical calculations and is found to agree with the dissociation energy of Si-H groups of about 3.25 eV per H atom, provided that the formation energy per dangling bond in ɑ-Si is about 1.15 eV. It is shown that this result is valid for ɑ-Si:H films, too

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The optical, mechanical, and microstructural properties of MgF2 single layers grown by ion beam sputtering have been investigated by spectrophotometric measurements, film stress characterization, x-ray photoelectron spectroscopy (XPS), x-ray diffraction, and transmission electron microscopy. The deposition conditions, using fluorine reactive gas or not, have been found to greatly influence the optical absorption and the stress of the films as well as their microstructure. The layers grown with fluorine compensation exhibit a regular columnar microstructure and an UV-optical absorption which can be very low, either as deposited or after thermal annealings at very low temperatures. On the contrary, layers grown without fluorine compensation exhibit a less regular microstructure and a high ultraviolet absorption which is particularly hard to cure. On the basis of calculations, it is shown that F centers are responsible for this absorption, whereas all the films were found to be stoichiometric, in the limit of the XPS sensitivity. On the basis of external data taken from literature, our experimental curves are analyzed, so we propose possible diffusion mechanisms which could explain the behaviors of the coatings.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Des dels inicis dels ordinadors com a màquines programables, l’home ha intentat dotar-los de certa intel•ligència per tal de pensar o raonar el més semblant possible als humans. Un d’aquests intents ha sigut fer que la màquina sigui capaç de pensar de tal manera que estudiï jugades i guanyi partides d’escacs. En l’actualitat amb els actuals sistemes multi tasca, orientat a objectes i accés a memòria i gràcies al potent hardware del que disposem, comptem amb una gran varietat de programes que es dediquen a jugar a escacs. Però no hi ha només programes petits, hi ha fins i tot màquines senceres dedicades a calcular i estudiar jugades per tal de guanyar als millors jugadors del món. L’objectiu del meu treball és dur a terme un estudi i implementació d’un d’aquests programes, per això es divideix en dues parts. La part teòrica o de l’estudi, consta d’un estudi dels sistemes d’intel•ligència artificial que es dediquen a jugar a escacs, estudi i cerca d’una funció d’avaluació vàlida i estudi dels algorismes de cerca. La part pràctica del treball es basa en la implementació d’un sistema intel•ligent capaç de jugar a escacs amb certa lògica. Aquesta implementació es porta a terme amb l’ajuda de les llibreries SDL, utilitzant l’algorisme minimax amb poda alfa-beta i codi c++. Com a conclusió del projecte m’agradaria remarcar que l’estudi realitzat m’ha deixat veure que crear un joc d’escacs no era tan fàcil com jo pensava però m’ha aportat la satisfacció d’aplicar tot el que he après durant la carrera i de descobrir moltes altres coses noves.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

En los últimos años se ha producido un incremento del uso de la telefonía móvil e Internet con fines intimidatorios o simplemente para amenazar a los iguales en los centros escolares de nuestro país. Con la voluntad de aportar datos que puedan ayudar a su prevención, se ha realizado un estudio de encuesta en el que se ha obtenido información relativa a las amenazas recibidas a través de los nuevos medios de comunicación, es decir, Internet y la telefonía móvil. Los resultados indican que un 23.3% de los estudiantes de los centros públicos de Enseñanza Secundaria Obligatoria de la ciudad de Girona (Cataluña), durante el curso escolar, han recibido vía Internet o telefonía móvil algún mensaje que, por su contenido, ha supuesto una amenaza para su bienestar. Se analizan las consecuenciasemocionales y las estrategias de afrontamiento utilizadas por parte de estos adolescentes

Relevância:

10.00% 10.00%

Publicador:

Resumo:

La evolución de la Ortopodología como ciencia aplicada a lo largo de los años ha sido muy amplia y variada. 3.000 años antes de J.C. se utilizaba el cuero para la confección de sandalias, posteriormente se introdujo el corcho, considerando éste como el único material natural que presenta a la vez una débil densidad, gran compresibilidad, fuerte elasticidad y gran duración. Tenemos constancia a través de la Enciclopedia de Diderot (S. XVIII) de la utilización del corcho tanto para fines terapéuticos como estéticos, así las...