AARHUS: 75 años: la torre, el vestíbulo y las escaleras: una reflexión estructural de la obra de Arne Jacobsen

Se acaba de cumplir el setenta y cinco aniversario de la inauguración de la sede del Ayuntamiento de Aarhus. Aarhus es la segunda ciudad en importancia de Dinamarca. En la tercera década del siglo XX su población rondaba los 120.00 habitantes. El edificio que alojaba su Ayuntamiento tenía por aquel entonces alrededor de ochenta años y estaba ubicado junto a la catedral de san Clemente en un inmueble que actualmente alberga el museo de Historia de la Mujer. La creciente actividad de la ciudad y el aumento significativo de su población fueron motivos más que suficientes como para plantear una nueva construcción que recogiera todas las funciones municipales ya que el edificio existente se había quedado pequeño. En 1937 se convoca un concurso nacional del que resultan ganadores Arne Jacobsen y Erik Møller. La municipalidad les exige que incluyan una torre en el proyecto ganador. El análisis estructural de esa torre permite recabar cómo los arquitectos la entienden como un elemento decorativo. Este hecho marcará la actitud de futuros proyectos y de sus elementos más significativos.Peer ReviewedPostprint (published version

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Spectrum Occupancy Estimation and Analysis

The goal of Cognitive Radio (CR) is to facilitate efficient utilization of the electromagnetic spectrum. CR applies spectrum sensing techniques to detect unused channels and then allows opportunistic usage of such channels by secondary users, i.e., un-licensed users, without interfering with primary users, i.e., licensed users. In order to implement a complete TV White Spaces (TVWS) based CR system, at first a model is needed that can be used for identifying TVWS, which can then be exploited for dynamic spectrum access. This work is focused on proposing a sensing method and building a probabilistic model for identifying the occupancy of the electromagnetic spectrum within the UHF TV bands. It also develops a hardware prototype for demonstrating the performance of the proposed technique. It proposes simultaneous sensing both noise and noise-contaminated user\u27s signal (composite signal) for detecting spectrum occupancy minimizing errors. The proposed sensing technique combines energy detection, pilot detection, and information obtained from an external source in order to reduce missed-detection probability. In addition to pre-defined threshold levels, the proposed probabilistic model considers parameters like probability of false alarm and probability of detection for measuring detection accuracy. Finally, a mobile sensing station is designed and implemented using off-the-shelf components to verify the developed technique for TVWS spectrum sensing. Using this mobile station, the UHF TV channels within the spectrum band of 500MHz-698MHz (Channel #19 to Channel 51) are scanned. Covering the total bandwidth of 198MHz, over 8 million data samples are collected through repeated scanning, ensuring possible spatio-temporal variations are taken into account. Results show that the availability of TVWS changes quite significantly with spatial variations. But, even in the most crowded spectrum locations, 28% of UHF channels were identified as TVWS. The model demonstrates about 10% improvement in detecting accuracy compared to other existing models

Preface. To research

Solaguren-Beascoa De Corral, F. (2023). Prefaci. Fer recerca. ANUARI d Arquitectura i Societat. (3):6-8. http://hdl.handle.net/10251/20132368

El asentamiento humano como indicador del cambio cultural: el caso de la región valenciana

El punto de partida de este articulo es el estudio del cambio cultural que se traduce en la aparición de sociedades cada vez mas complejas. Se toma como base un aspecto: el del asentamiento humano en el área valenciana, ya que las sistematizaciones y estratigrafías de la misma permiten establecer una secuencia mas firme. El estudio se inicia con los escasos datos del epipaleolítico y concluye con la aparición de los cambios que anuncian ya la edad del bronce. Se constata la dualidad del hábitat, en cueva y al aire libre, prácticamente desde el inicio de la secuencia, un desplazamiento al asentamiento en superficie, favorecido por los factores ambientales, en el eneolítico y la construcción de dispositivos de defensa en la edad del bronce. Se discuten las posibles causas del cambio y los tipos de sociedad de los que son reflej

Anomalous Transport in Conical Granular Piles

Experiments on 2+1-dimensional piles of elongated particles are performed. Comparison with previous experiments in 1+1 dimensions shows that the addition of one extra dimension to the dynamics changes completely the avalanche properties, appearing a characteristic avalanche size. Nevertheless, the time single grains need to cross the whole pile varies smoothly between several orders of magnitude, from a few seconds to more than 100 hours. This behavior is described by a power-law distribution, signaling the existence of scale invariance in the transport process.Comment: Accepted in PR

Point-occurrence self-similarity in crackling-noise systems and in other complex systems

It has been recently found that a number of systems displaying crackling noise also show a remarkable behavior regarding the temporal occurrence of successive events versus their size: a scaling law for the probability distributions of waiting times as a function of a minimum size is fulfilled, signaling the existence on those systems of self-similarity in time-size. This property is also present in some non-crackling systems. Here, the uncommon character of the scaling law is illustrated with simple marked renewal processes, built by definition with no correlations. Whereas processes with a finite mean waiting time do not fulfill a scaling law in general and tend towards a Poisson process in the limit of very high sizes, processes without a finite mean tend to another class of distributions, characterized by double power-law waiting-time densities. This is somehow reminiscent of the generalized central limit theorem. A model with short-range correlations is not able to escape from the attraction of those limit distributions. A discussion on open problems in the modeling of these properties is provided