26 resultados para George, Stefan Anton, 1868-1933.

em Consorci de Serveis Universitaris de Catalunya (CSUC), Spain


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Treball de recerca realitzat per una alumna d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l'any 2009. El present treball és un estudi de la personalitat humana, literària i filosòfica de Jaume Brossa així com un anàlisi del medi sociohistòric que li va tocar viure. El mètode utilitzat ha estat, en primer lloc, un rastreig de material original, articles publicats entre els anys 1892 i 1902 en diversos òrgans de premsa de Barcelona i Madrid. Una vegada obtingut el material requerit, s’ha sondejat per dins de les seves línies fins a trobar quin era el seu pensament en molts aspectes, a saber: el seu posicionament entorn els grans centres d’atenció del seu temps: el nacionalisme, el moviment obrer, l’estètica modernista en les seves parcel•les de música, literatura, teatre etc., tots aquests camps, tractats des de la base de la seva actitud regeneracionista i revolucionària. L’estudi s’ha realitzat des d’un enfocament crític: intentar esbrinar quines han estat les causes per les quals un autor certament notable de les nostres lletres ha estat marginat o, si més no, minimitzat en el seu abast intel•lectual. I, tal com es planteja al començament del treball, aquest consta d’una recerca de causes, implicacions, contextos etc. que ens permetin esbrinar per què Jaume Brossa ha estat desacreditat.

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When using a polynomial approximating function the most contentious aspect of the Heat Balance Integral Method is the choice of power of the highest order term. In this paper we employ a method recently developed for thermal problems, where the exponent is determined during the solution process, to analyse Stefan problems. This is achieved by minimising an error function. The solution requires no knowledge of an exact solution and generally produces significantly better results than all previous HBI models. The method is illustrated by first applying it to standard thermal problems. A Stefan problem with an analytical solution is then discussed and results compared to the approximate solution. An ablation problem is also analysed and results compared against a numerical solution. In both examples the agreement is excellent. A Stefan problem where the boundary temperature increases exponentially is analysed. This highlights the difficulties that can be encountered with a time dependent boundary condition. Finally, melting with a time-dependent flux is briefly analysed without applying analytical or numerical results to assess the accuracy.

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The work in this paper concerns the study of conventional and refined heat balance integral methods for a number of phase change problems. These include standard test problems, both with one and two phase changes, which have exact solutions to enable us to test the accuracy of the approximate solutions. We also consider situations where no analytical solution is available and compare these to numerical solutions. It is popular to use a quadratic profile as an approximation of the temperature, but we show that a cubic profile, seldom considered in the literature, is far more accurate in most circumstances. In addition, the refined integral method can give greater improvement still and we develop a variation on this method which turns out to be optimal in some cases. We assess which integral method is better for various problems, showing that it is largely dependent on the specified boundary conditions.

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In this paper we present a new, accurate form of the heat balance integral method, termed the Combined Integral Method (or CIM). The application of this method to Stefan problems is discussed. For simple test cases the results are compared with exact and asymptotic limits. In particular, it is shown that the CIM is more accurate than the second order, large Stefan number, perturbation solution for a wide range of Stefan numbers. In the initial examples it is shown that the CIM reduces the standard problem, consisting of a PDE defined over a domain specified by an ODE, to the solution of one or two algebraic equations. The latter examples, where the boundary temperature varies with time, reduce to a set of three first order ODEs.

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Rehabilitació de la planta baixa d'una casa en la reconversió a disseny d'interior d'un local comercial destinat a exposició i venda d'objectes de regal de plata, cristall i porcellana. On actualment ja s'establia a la banda esquerra una botiga que es reaprofitarà. També s'inclou la rehabilitació de façana del mateix local.

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Treball que tracta d’explicar el procés de creació d’un personatge polític, en el que s’utilitza a George W. Bush com a exemple pràctic per il·lustrar les estratègies implementades pel seu assessor Karl Rove per portar-lo a la Casa Blanca.

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Les especialitats mèdiques van tenir un ràpid desenvolupament al món occidental a principis del segle XX. La situació de Catalunya abans de la Guerra Civil, situada als confins de l’Europa d’entreguerres, afavoreix els intents de comunicació científica entre metges catalans i occitans més enllà de les fronteres de grans estats, Espanya i França, amb l’ús d’una llengua pròpia vehicular, el català. Així neix a Barcelona el 1933 la revista La Medicina Catalana, sota la direcció de Leandre Cervera i Astor, constituïda principalment per ressenyes en català d’articles apareguts a revistes internacionals. L’objectiu és estudiar l’aparició i consolidació de les especialitats mèdiques a Catalunya.

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Single layers of MgF2 and LaF3 were deposited upon superpolished fused-silica and CaF2 substrates by ion-beam sputtering (IBS) as well as by boat and electron beam (e-beam) evaporation and were characterized by a variety of complementary analytical techniques. Besides undergoing photometric and ellipsometric inspection, the samples were investigated at 193 and 633 nm by an optical scatter measurement facility. The structural properties were assessed with atomic-force microscopy, x-ray diffraction, TEM techniques that involved conventional thinning methods for the layers. For measurement of mechanical stress in the coatings, special silicon substrates were coated and analyzed. The dispersion behavior of both deposition materials, which was determined on the basis of various independent photometric measurements and data reduction techniques, is in good agreement with that published in the literature and with the bulk properties of the materials. The refractive indices of the MgF2 coatings ranged from 1.415 to 1.440 for the wavelength of the ArF excimer laser (193 nm) and from 1.435 to 1.465 for the wavelength of the F2 excimer laser (157 nm). For single layers of LaF3 the refractive indices extended from 1.67 to 1.70 at 193 nm to ~1.80 at 157 nm. The IBS process achieves the best homogeneity and the lowest surface roughness values (close to 1 nmrms) of the processes compared in the joint experiment. In contrast to MgF2 boat and e-beam evaporated coatings, which exhibit tensile mechanical stress ranging from 300 to 400 MPa, IBS coatings exhibit high compressive stress of as much as 910 MPa. A similar tendency was found for coating stress in LaF3 single layers. Experimental results are discussed with respect to the microstructural and compositional properties as well as to the surface topography of the coatings.

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En aquest llibre trobem l'obra de 1672 "Principios de cirugía útiles y provechosos, para que puedan aprovecharse los principiantes en esta facultad" del cirurgià espanyol Jerónimo de Ayala. És una còpia editada per Carles Pallejà a partir d'una traducció d'Anton de Borja.Tot plegat ve presentat i acompanyat d'un estudi de l'autor, Pere Vallribera, així com d'una crítica històrica del text original i el seu context.

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L'anàlisi de nombrosos inventaris procedents dels Pirineus centrals i orientals ens ha dut a realitzar una revisió de I'aliança Polygonion avicularis Br.-Bl. ex Dich 1933 en aquesta àrea. Reconeixem fins al moment sis associacions per a les quals donem la seva caracterització florística i ecologica, així com la seva distribució als Pirineus catalans. Descrivim, a més, una subass. scleranthetosum uncinatae del Rumici-Spergularietum rubrae, comunitat altimontana i subalpina pròpia dels sòls calcigats.

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E Darre rament, e l concepte resili cncia s' ha fet molt present en e ls discursos tècnics del camp soc ial. Ara bé, e ls usos que se li estan donant són múlti ples i en alguns casos molt diferenciats entre ells. Per cl arificar e l sentit ini c ial de l concepte hem mantingut una: conversa amb el professor Stefan VanistendaeL una de les persones que més ha desenvolupat aquest concepte i explorat les seves aplicacions.

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During this first third of this century, the continent of Europe witnessed far-reaching territorial transformations in the nineteenth century model. To some extent, the setting wich had inspired the epistemological structure of the French regional school was being replaced by one in which -at least to externa1 appearances- the relationship between the physical environment and human activities was much less evident. The adaptation of the theoretical and methodological context to the new Europe seems to take the form of a non-lineal evolution, for in the latter years of the period examined, evolutionary tendencies indicate a return to the more classical model. In this way, the growing interest which the publication had shown in Atlantic Europe and topics of a more economic nature, was truncated. The traditional settings --especially the Mediterranean- came to the fore again and interest in rural societies was renewed. Likewise, the monographic studies which had demonstrated distinct functional objectives in the midtwenties, recovered elements of ecological explanation, and the search for the relationship between environment and society

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