Un modelo directo de interacción peatón-estructura para caracterizar las vibraciones inducidas por peatones en pasarelas esbeltas

Although the scientific community had knowledge of the human induced vibration problems in structures since the end of the 19th century, it was not until the occurrence of the vibration phenomenon happened in the Millennium Bridge (London, 2000) that the importance of the problem revealed and a higher level of attention devoted. Despite the large advances achieved in the determination of the human-structure interaction force, one of the main deficiencies of the existing models is the exclusion of the effect of changes in the footbridge dynamic properties due to the presence of pedestrians. In this paper, the formulation of a human-structure interaction model, addresses these limitations, is carried out and its reliability is verified from previously published experimental results.Aunque la comunidad científica tenía conocimiento de los problemas vibratorios inducidos por peatones en estructuras desde finales del siglo xix, no fue hasta la ocurrencia de los eventos vibratorios acontecidos en la pasarela del Milenio (Londres, 2000), cuando la importancia del problema se puso de manifiesto y se le comenzó a dedicar un mayor nivel de atención. A pesar de los grandes avances alcanzados en la caracterización de la fuerza de interacción peatón-estructura una de las principales deficiencias de los modelos existentes es la exclusión del cambio en las propiedades dinámicas de la pasarela por la presencia de peatones. En este artículo, se presenta la formulación de un modelo de interacción peatón-estructura que intenta dar respuesta a dichas limitaciones, y su validación a partir de resultados experimentales previamente publicados por otros autores

Sine Cerere et Baccho friget Venus: un proverbio clásico en Lope de Vega

Este estudio examina la aparición de un proverbio terenciano (“Sine Cerere et Baccho friget Venus”) en la obra de Lope. Tras mostrar que el Fénix lo emplea en al menos diez de sus obras, explicamos que debió de encontrarlo no en su fuente original, sino en alguno de los manuales de retórica del momento, en los que se usaba como ejemplo metonimia. Asimismo, precisamos que Lope solo usa el proverbio a partir de la Arcadia, tal vez debido a su intento de presentarse como un autor prestigioso, y que la mayoría de las menciones proceden de la época del reinado de Felipe III. Por último, clasificamos los usos según respondan a preocupaciones retóricas, amorosas, religiosas, cortesanas o burlescas, explicando cómo cambia en cada una de estas líneas

Influence of Energy and Temperature in Cluster Coalescence Induced by Deposition

Coalescence induced by deposition of different Cu clusters on an epitaxial Co cluster supported on a Cu(001) substrate is studied by constant-temperature molecular dynamics simulations. The degree of epitaxy of the final system increases with increasing separation between the centres of mass of the projectile and target clusters during the collision. Structure, roughness, and epitaxial order of the supported cluster also influence the degree of epitaxy. The effect of energy and temperature is determinant on the epitaxial condition of the coalesced cluster, especially both factors modify the generation, growth and interaction among grains. A higher temperature favours the epitaxial growth for low impact parameters. A higher energy contributes to the epitaxial coalescence for any initial separation between the projectile and target clusters. The influence of projectile energy is notably greater than the influence of temperature since higher energies allow greater and instantaneous atomic reorganizations, so that the number of arisen grains just after the collision becomes smaller. The appearance of grain boundary dislocations is, therefore, a decisive factor in the epitaxial growth of the coalesced cluster

A Connection Between Pattern Classification by Machine Learning and Statistical Inference With the General Linear Model

A connection between the general linear model (GLM) with frequentist statistical testing and machine learning (MLE) inference is derived and illustrated. Initially, the estimation of GLM parameters is expressed as a Linear Regression Model (LRM) of an indicator matrix; that is, in terms of the inverse problem of regressing the observations. Both approaches, i.e. GLM and LRM, apply to different domains, the observation and the label domains, and are linked by a normalization value in the least-squares solution. Subsequently, we derive a more refined predictive statistical test: the linear Support Vector Machine (SVM), that maximizes the class margin of separation within a permutation analysis. This MLE-based inference employs a residual score and associated upper bound to compute a better estimation of the actual (real) error. Experimental results demonstrate how parameter estimations derived from each model result in different classification performance in the equivalent inverse problem. Moreover, using real data, the MLE-based inference including model-free estimators demonstrates an efficient trade-off between type I errors and statistical power.Ministerio de Ciencia e Innovacion (Espana)/FEDER RTI2018-098913B100Junta de AndaluciaEuropean Commission CV20-45250 A-TIC-080-UGR18 P20-00525National Health and Medical Research Council (NHMRC) of Australia 18/0490

Maximum Likelihood Finite-Element Model Updating of Civil Engineering Structures Using Nature-Inspired Computational Algorithms

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordIn finite-element model updating, numerical models are calibrated in order to better mimic the real behaviour of structures. Such updating process is usually performed under the maximum likelihood method in practical engineering applications. According to this, the updating problem is transformed into an optimization problem. The objective function of this problem is usually defined in terms of the relative differences between the numerical and the experimental modal properties of the structure. To this aim, either (1) a single-objective or (2) a multi-objective approach may be adopted. Due to the complexity of the problem, global optimizers are usually considered for its solution. Among these algorithms, nature-inspired computational algorithms have been widely employed. Nevertheless, such model updating approach presents two main limitations: (1) a clear dependence between the updated model and the objective function considered; and (2) a high computational cost. In order to overcome these drawbacks, a detailed study has been performed herein both to establish the most adequate objective function to tackle the problem and to further assist in the selection of the most efficient computational algorithm among several well-known ones. For this purpose, a laboratory footbridge has been considered as benchmark to conduct the updating process under different scenarios.Ministerio de Economía y Competitividad of SpainEuropean Regional Development FundUniversidad de Sevill

Drivers of the Ectoparasite Community and Co-Infection Patterns in Rural and Urban Burrowing Owls

We analyzed the ectoparasite community of a monomorphic and non-social bird, the burrowing owl, Athene cunicularia, breeding in rural and urban habitats. Such community was composed by two lice, one mite and one flea species. Rural individuals had more fleas and less mites than urban ones. Adult birds harbored less ectoparasites than young ones and females harbored more lice than males. The presence of lice was positively related to the presence of fleas. On the contrary, the presence of mites was negatively related to the presence of fleas and lice. The study of parasite communities in urban and rural populations of the same species can shed light on how urban stressor factors impact the physiology of wildlife inhabiting cities and, therefore, the host-parasite relationships. Urbanization creates new ecological conditions that can affect biodiversity at all levels, including the diversity and prevalence of parasites of species that may occupy these environments. However, few studies have compared bird-ectoparasite interactions between urban and rural individuals. Here, we analyze the ectoparasite community and co-infection patterns of urban and rural burrowing owls, Athene cunicularia, to assess the influence of host traits (i.e., sex, age, and weight), and environmental factors (i.e., number of conspecifics per nest, habitat type and aridity) on its composition. Ectoparasites of burrowing owls included two lice, one flea, and one mite. The overall prevalence for mites, lice and fleas was 1.75%, 8.76% and 3.50%, respectively. A clear pattern of co-infection was detected between mites and fleas and, to less extent, between mites and lice. Adult owls harbored fewer ectoparasites than nestlings, and adult females harbored more lice than males. Our results also show that mite and flea numbers were higher when more conspecifics cohabited the same burrow, while lice showed the opposite pattern. Rural individuals showed higher flea parasitism and lower mite parasitism than urban birds. Moreover, mite numbers were negatively correlated with aridity and host weight. Although the ectoparasitic load of burrowing owls appears to be influenced by individual age, sex, number of conspecifics per nest, and habitat characteristics, the pattern of co-infection found among ectoparasites could also be mediated by unexplored factors such as host immune response, which deserves further research

Strandings of cetaceans and sea turtles in the Alboran Sea and Strait of Gibraltar: a long-term glimpse at the north coast (Spain) and the south coast (Morocco)

., 2011. Strandings of cetaceans and sea turtles in the Alboran Sea and Strait of Gibraltar: a long-time glimpse of the north coast (Spain) and the south coast (Morocco). Animal Biodiversity and Conservation, 34.1: 151-163. Abstract Strandings of cetaceans and sea turtles in the Alboran Sea and Strait of Gibraltar: a long-term glimpse at the north coast (Spain) and the south coast (Morocco) .-A total of 13 species of cetaceans and three species of marine turtles were found in this study. Data were collected by eight independent and self-regulated stranding networks, providing information about 1,198 marine mammal (10 odontocetii, three mysticetii and one phocidae) and 574 sea turtle stranding events between 1991 and 2008. Trends in the strandings were analysed in relation to species composition and abundance, and their geographic and seasonal distribution. The most abundant species recorded were the striped dolphin and the loggerhead turtle. Some of the strandings, such as the humpback whale, harbour porpoise, hooded seal and olive ridley turtle, were considered 'rare' because their distribution did not match the pattern of the study. When the north and south coasts in the study area were compared, pilot whales stranded more frequently in the north, while delphinid species stranded more in the south coast, and loggerhead turtles stranded more frequently in the north while leatherback turtles stranded more in south coast. Key words: Strandings, South-western Mediterranean, Distribution, Marine turtle, Cetacean, Conservation. Resumen Varamientos de cetáceos y tortugas marinas en el mar de Alborán y el Estrecho de Gibraltar: un vistazo a largo plazo de la costa norte (España) y la costa sur (Marruecos) .-En este estudio se registraron un total de 13 especies de cetáceos y tres especies de tortugas marinas, proviniendo los datos de redes de voluntarios que prestan asistencia en los varamientos. Se recogió información de 1.198 mamiferos marinos (10 odontocetos, tres misticetos y un fócido) y 574 tortugas marinas entre los años 1991 y 2008. Se analizaron las tendencias de los varamientos en relación a la composición de especies, su abundancia y su distribución geográfica y estacional. Las especies más comunes fueron el delfín común y la tortuga boba. Algunos de los varamientos, como la ballena jorobada, la marsopa común, la foca de casco o la tortuga olivácea, pueden considerarse "anómalos" puesto que su distribución se escapa a los patrones del estudio. Comparando la costa norte del área de estudio con la sur, los calderones y tortugas bobas vararon con mayor frecuencia en la costa norte, mientras que las especies de delfines y las tortugas laúd vararon con mayor frecuencia en la costa sur