Seismic vulnerability analysis of steel buildings in Bogotá, Colombia

A number of mid-height steel buildings have been erected recently in Bogotá. Their seismic risk might be high, given the new microzonation of Bogotá and the lack of previous studies; remarkably, the response reduction factors were commonly obtained from general recommendations. The objective of this work is to investigate the seismic performance of these buildings. This study is carried out on eighteen representative buildings. All these edifices have plan symmetry and are uniform along their height. Span-length: 6 ¿ 8 m; number of floors: 5, 10, 15. Earthquake-resistant systems: moment-resistant frames, concentrically-braced frames and eccentricallybraced frames (using chevron braces). For each building, eight seismic zones have been considered. The vulnerability has been evaluated by “push-over” analyses. In the moment-resistant frames and in the eccentrically-braced frames the nonlinearities are concentrated in the plastic hinges near the connections; in the concentrically-braced frames the nonlinearities are allocated in the braces.Postprint (published version

New methodology for calculating damage variables evolution in Plastic Damage Model for RC structures

The behavior of reinforced concrete (RC) structures under severe demands, as strong ground motions, is highly complex; this is mainly due to joint operation of concrete and steel, with several coupled failure modes. Furthermore, given the increasing awareness and concern for the important seismic worldwide risk, new developments have arisen in earthquake engineering. Nonetheless, simplified numerical models are widely used (given their moderate computational cost), and many developments rely mainly on them. The authors have started a long-term research whose final objective is to provide, by using advanced numerical models, solid basis for these developments. Those models are based on continuum mechanics, and consider Plastic Damage Model to simulate concrete behavior. Within this context, this paper presents a new methodology to calculate damage variables evolution; the proposed approach is based in the Lubliner/Lee/Fenves formulation and provides closed-form expressions of the compressive and tensile damage variables in terms of the corresponding strains. This methodology does not require calibration with experimental results and incorporates a strategy to avoid mesh-sensitivity. A particular algorithm, suitable for implementation in Abaqus, is described. Mesh-insensitivity is validated in a simple tension example. Accuracy and reliability are verified by simulating a cyclic experiment on a plain concrete specimen. Two laboratory experiments consisting in pushing until failure two 2-D RC frames are simulated with the proposed approach to investigate its ability to reproduce actual monotonic behavior of RC structures; the obtained results are also compared with the aforementioned simplified models that are commonly employed in earthquake engineering.Postprint (published version

El microcrédito como instrumento de financiación al servicio de las entidades de economía social. Especial referencia al instrumento europeo de microfinanciación Progress

El panorama, tres años después del inicio de la crisis financiera internacional en agosto de 2007, no es muy distinto del inicial, por lo que la denominada microfinanciación puede dar algo de luz en el sombrío entramado de la financiación empresarial. El objetivo de este trabajo es poner de manifiesto que, si bien la microfinanciación es esencial para cualquier empresa, lo es más para las entidades de economía social dadas las dificultades de acceso al crédito tradicional por las peculiaridades que presenta su estructura de capital. Contar con instrumentos financieros adecuados para las empresas del sector de la economía social es condición esencial para el crecimiento económico que nos haga sortear la crisis y que asegure el cumplimiento de la política social a que están llamadas a cumplir las citadas entidades. Por ello cabe acoger favorablemente el desarrollo de instrumentos financieros como el “instrumento europeo de microfinanciación Progress”, aprobado por el Parlamento europeo y destinado específicamente a microempresas del sector de la economía social y a grupos desfavorecidos. La puesta en marcha de estos microcréditos precisa una estructura organizativa que permita procesar de manera normalizada un elevado número de solicitudes, y esa estructura puede ser prestada por las cooperativas de crédito. Resulta generalizada la idea de que el origen del microcrédito se sitúa en la creación del Grameen Bank, pero existen antecedentes, tanto en España como en otros países europeos, que sitúan al instrumento financiero del microcrédito en el origen del nacimiento de las cooperativas de crédito, por lo que la experiencia pasada puede ser aplicada al momento actual

A Bayesian Hyperprior Approach for Joint Image Denoising and Interpolation, with an Application to HDR Imaging

Recently, impressive denoising results have been achieved by Bayesian approaches which assume Gaussian models for the image patches. This improvement in performance can be attributed to the use of per-patch models. Unfortunately such an approach is particularly unstable for most inverse problems beyond denoising. In this work, we propose the use of a hyperprior to model image patches, in order to stabilize the estimation procedure. There are two main advantages to the proposed restoration scheme: Firstly it is adapted to diagonal degradation matrices, and in particular to missing data problems (e.g. inpainting of missing pixels or zooming). Secondly it can deal with signal dependent noise models, particularly suited to digital cameras. As such, the scheme is especially adapted to computational photography. In order to illustrate this point, we provide an application to high dynamic range imaging from a single image taken with a modified sensor, which shows the effectiveness of the proposed scheme.Comment: Some figures are reduced to comply with arxiv's size constraints. Full size images are available as HAL technical report hal-01107519v5, IEEE Transactions on Computational Imaging, 201

Fortalezas, debilidades y tendencias en los gabinetes de comunicación

En esta ponencia ofrecemos parte de los resultados de un reciente estudio sobre los gabinetes de comunicación en Andalucía (se analizaron más de trescientos gabinetes). Concretamente, analizamos cuáles son los principales problemas que el sector presenta en la actualidad (intrusismo, ausencia de una clara delimitación funcional, confusión terminológica, etc.) y cuáles debería ser los retos de la profesión ante el fututo inmediato, para salvar las actuales deficiencias y lograr la tan ansiada consolidación. La formación y la concienciación social son, desde luego, imprescindibles para alcanzar este objetivo.En la "sociedad del conocimiento", las necesidades en comunicación han crecido a un ritmo acelerado en el seno de las organizaciones. Por ello, se han ido creando gabinetes de comunicación, que satisfacen estas necesidades comunicativas. Sin embargo, el proceso aún está inconcluso en Andalucía y en España en general, ya que aún debe consolidarse la comunicación como elemento clave en muchas organizaciones

Analysing musical performance through functional data analysis: rhythmic structure in Schumann's Träumerei

Functional data analysis (FDA) is a relatively new branch of statistics devoted to describing and modelling data that are complete functions. Many relevant aspects of musical performance and perception can be understood and quantified as dynamic processes evolving as functions of time. In this paper, we show that FDA is a statistical methodology well suited for research into the field of quantitative musical performance analysis. To demonstrate this suitability, we consider tempo data for 28 performances of Schumann's Träumerei and analyse them by means of functional principal component analysis (one of the most powerful descriptive tools included in FDA). Specifically, we investigate the commonalities and differences between different performances regarding (expressive) timing, and we cluster similar performances together. We conclude that musical data considered as functional data reveal performance structures that might otherwise go unnoticed.Peer ReviewedPostprint (author's final draft