4,823 research outputs found

    Juan Talavera de La Vega‘s plans of works derived from the land donation to create the Parque de María Luisa in Seville

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    Juan Talavera y de la Vega, arquitecto del Palacio de San Telmo, fue el responsable del diseño de las construcciones que debían realizarse en el palacio a consecuencia de la donación por parte de la infanta María Luisa Fernanda de un área de sus jardines a la ciudad de Sevilla para crear un parque público. En agosto de 1893, Talavera remitió al Ayuntamiento los planos que se analizan en estas páginas. Los adjuntaban a un informe donde explicaba la incidencia de la apertura de la nueva avenida que servía de límite a los terrenos cedidos y de la demolición de diferentes construcciones, en especial, el antiguo Convento de San Diego, dedicado a las caballerizas y estancias de servicios del palacio y las viviendas de su personal.María Luisa Fernanda, Duchess of Montpensier, donated an important part of her gardens of St. Telmo’s Palace to the city of Seville in order to create a public park. Juan Talavera de la Vega, chief architect of the palace, was responsible for the design of buildings to be carried out in the palace as a result of the cession. The plans we study in these pages, were submitted to Town Hall by in August 1893. They were attached to a report explaining the impact of opening the new avenue bordering the ceded lands, and demolishing different buildings dedicated to stables, palace service rooms and staff housing, especially the old St. Diego’s Convent

    Looking for Simple Common Schemes to Design Recognizer P Systems with Active Membranes That Solve Numerical Decision Problems

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    Earlier solutions to decision problems by means of P systems used many counter objects to control the synchronization of different stages in a computation (usually as many counters as the stage must last in the worst case). In this paper we propose a way to replace those counters with some spacial objects for each stage. Furthermore, following the ideas presented in [1], in order to have a common scheme to attack numerical problems, all instances of a problem with the same size are solved by the same P system (which depends on the size) given an input which describes the corresponding instance of the problem. We illustrate these ideas with a cellular solution to the Subset-Sum problem

    Normativa y legislación constructiva en la Antigüedad y en la alta Edad Media

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    Interaction of oxygen with TiN (001): N↔O exchange and oxidation process

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    This work presents a detailed experimental and theoretical study of the oxidation of TiN(001) using a combination of synchrotron-based photoemission and density functional theory (DFT). Experimentally, the adsorption of O2 on TiN(001) was investigated at temperatures between 250 and 450K. At the lowest temperature, there was chemisorption of oxygen (O2,gas→2Oads) without significant surface oxidation. In contrast, at 450K the amount of O2 adsorbed increased continuously, there was no evidence for an oxygen saturation coverage, a clear signal in the Ti 2p core level spectra denoted the presence of TiOx species, and desorption of both N2 and NO was detected. The DFT calculations show that the adsorption/dissociation of O2 is highly exothermic on a TiN(001) substrate and is carried out mainly by the Ti centers. A high oxygen coverage (larger than 0.5 ML) may induce some structural reconstructions of the surface. The exchange of a surface N atom by an O adatom is a highly endothermic process (ΔE=2.84eV). However, the overall oxidation of the surface layer is thermodynamically favored due to the energy released by the dissociative adsorption of O2 and the formation of N2 or NO. Both experimental and theoretical results lead to conclude that a TiN+mO2→TiOx+NO reaction is an important exit channel for nitrogen in the oxidation process.Ministerio de Educación y Ciencia de España, MEC. MAT2005-01872Junta de Andalucía. FQM-132División de Ciencias Químicas del Departamento de Energía de EE. UU. DE-AC02-98CH10086Fundación japonesa para la Ciencia de los Materiale

    A theoretical insight into the catalytic effect of a mixed-metal oxide at the nanometer level: The case of the highly active metal/CeOx/TiO2(110) catalysts

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    The structural and electronic properties of CeOx species supported on the rutile TiO2 110 surface have been examined by means of periodic density-functional calculations that use a generalized gradient approximation functional including a Hubbard-like type correction. Deposition of Ce atoms leads in a first step to Ce3+ ions bound to the surface through bridge and in-plane oxygen atoms, the released electrons occupying the Ti 3d empty orbitals. Further addition of Ce and molecular oxygen gives place to Ce2O3 dimers diagonally arranged on the surface, in agreement with the spots observed in the scanning tunnel microscope images. The formation process of CeOx nanoparticles NPs on the TiO2 surface is highly exothermic and our calculations show that the redox properties of the Ce III-Ce IV couple are significantly altered when it is supported on TiO2. In particular the reactivity against CO/O2 indicates that on the surface the presence of Ce III is favored over Ce IV species. Our results also indicate that the CeOx /TiO2 interface should be seen like a real mixed-metal oxide rather than a supported NP of ceria. Finally, in the context of the high catalytic activity of the M /CeOx /TiO2 M =Au,Cu,Pt systems in the water-gas shift reaction, we have examined the dissociation of water on the CeOx /TiO2 surface and estimated a barrier as small as 0.04 eV, i.e. 8 times smaller than that computed for a TiO2 oxygen vacancy. This result agrees with the experimental superior catalytic activity of the M /CeOx /TiO2 systems over M /TiO2.Gobierno de España. Ministerio Ciencia e Innovación (MICINN) MAT2005-01872 y CSD2008-0023Junta de Andalucía FQM-132Departamento de Energía de EE. UU. División de Subvención de Ciencias Químicas DE-AC02-98CH1088

    Hacia el nacimiento de la Historia de la Construcción. Origen y devenir de una Ciencia

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