Estabilidad y convergencia de esquemas numéricos para sistemas de Dirac no lineales

Siguiendo una técnica desarrollada por López-Marcos y Sanz-Serna, probamos la estabilidad y convergencia de tres esquenias en diferencias finitas para la solución numérica de sistemas de Dirac no lineales. Los esquemas se comparan por medio de experimentos numéricos.Peer Reviewe

Robust design optimization using Kriging models: Application to the robust design optimization of truss structures

El problema de diseño óptimo robusto de estructuras es una tarea computacionalmente costosa como consecuencia del acoplamiento de los procesos de cuantificación de incertidumbre y de optimización. Para hacer frente a este problema, en este artículo se propone una metodología, basada en modelos Kriging, para resolver de forma eficiente el problema de cuantificación de incertidumbre en el proceso de optimización. El modelo Kriging aproxima, de forma simultánea, la respuesta estructural en el dominio de diseño y en el dominio estocástico, permitiendo desacoplar los procesos de cuantificación de incertidumbre y de optimización. La metodología propuesta incluye un criterio de actualización de los modelos Kriging basado en la estimación del error en la predicción, que mejora la aproximación en las regiones cercanas al frente de Pareto. Se han resuelto 3 problemas para mostrar la aplicabilidad y la precisión de la metodología propuesta. Los resultados muestran que la metodología es adecuada para resolver el problema de diseño óptimo robusto con una precisión razonable y un número de evaluaciones del modelo de simulación muy inferior al que requieren los métodos convencionales.Conventional methods addressing the robust design optimization problem of structures usually require high computational requirements due to the nesting of uncertainty quantification within the optimization process. In order to address such a problem, this work proposes a methodology, based on Kriging models, to efficiently assess the uncertainty quantification in the optimization process. The Kriging model approximates the structural performance both in the design domain and in the stochastic domain, which allows to decouple the uncertainty quantification process and the optimization process. In addition, an infill criterion based on the variance of the Kriging prediction is included to update the Kriging model towards the global Pareto front. Three numerical examples show the applicability and the accuracy of the proposed methodology. The results show that the proposed method is appropriate to solve the robust design optimization problem with reasonable accuracy and a considerably lower number of function calls than required by conventional methods.Peer Reviewe

Homo- and Heteroleptic Copper(I) Complexes with Diazabutadiene Ligands: Synthesis, Solution- and Solid-State Structural Studies

The preparation of novel copper(I) complexes of diazabutadiene (DAB) ligands with aliphatic backbones is reported. [Cu(DABR)2](BF4), [Cu(DABR)(NCMe)2](BF4) and [CuCl(DABR)] are easily synthesised and air-stable. These complexes, which remain scarce in the literature, have been fully characterised, and their behaviour both in the solid state as well as in solution has been studied by means of X-ray crystallography, NMR and UV/Vis spectroscopy

Optimal adaptation strategies to face shocks on groundwater resources

We consider an exogenous and reversible shock to a groundwater resource, namely a decrease in the recharge rate of the aquifer. We compare optimal extraction paths and the social costs of optimal adaptation in two cases: under certainty, i.e. when the date of occurrence of the shock is known, and under uncertainty, when the date of occurrence of the shock is a random variable. We show that an increase in uncertainty leads to a decrease in precautionary behavior in the short run and to an increase in precautionary behavior in the long run. We apply our model to the particular case of the Western la Mancha aquifer in Spain. We show that, in this context, it is advantageous for the water agency to acquire information on the date of the shock, especially for high-intensity and intermediate-risk events

Anthropometric measures as predictive indicators of metabolic risk in a population of “holy week costaleros”

Preventive measures are a priority in those groups that perform intense physical efforts without physical preparation and that can also be overweight or obese. One of the groups that reflect these characteristics is the costaleros of the Holy Week of Andalusia, Spain. This paper aims to describe the effect of obesity on blood pressure. A descriptive cross-sectional study was conducted on 101 costaleros. The anthropometric measures were determined through segmental impedance. Cardiac recovery and anaerobic power were measured through the Ruffier–Dickson test and the Abalakov test, respectively. Blood pressure was measured when the individuals were at rest. The Kruskal–Wallis test was applied for of continuous parameters and the X2 test for dichotomous measures. Binary logistic regression models were used for the subsequent analysis with R-square and Receiver Operating Characteristic (ROC) curves. The average population was 28 years of age, 173.7 cm tall, and 82.59 Kg weigh. The excess of body fat was 11.27 Kg and Body Mass Index was 27.33 Kg/m2. 72.3% showed abnormal blood pressure and 68.2% were overweight. 32.7% had a waist-hip ratio higher than 0.94. The probability of presenting abnormal blood pressure was higher among the subjects whose fat content was higher and muscle content was lower

Cinemómetro piezoeléctrico de alta exactitud (VUAE)

Se ha desarrollado un sistema electrónico computerizado, portátil y de bajo consumo, denominado Medidor de Velocidad de Vehículos por Ultrasonidos de Alta Exactitud, VUAE. La alta exactitud de la medida conseguida en el VUAE hace que pueda servir de medida de referencia de la velocidad de un vehículo circulando en carretera. Por tanto el VUAE puede usarse como medida de referencia que permita estimar el error de los cinemómetros comerciales. El VUAE está compuesto por n (n≥2) parejas de emisores y receptores piezoeléctricos de ultrasonidos, denominados E-Rult. Los emisores de las n parejas E-Rult generan n barreras de ultrasonidos, y los receptores piezoeléctricos captan la señal de los ecos cuando el vehículo atraviesa las barreras. Estos ecos se procesan digitalmente para conseguir señales representativas. Posteriormente, utilizando la técnica de la correlación cruzada de señales, se ha podido estimar con alta exactitud la diferencia de tiempos entre los ecos captados en cada barrera. Con los tiempos entre ecos y con la distancia entre cada una de las n barreras de ultrasonidos se puede realizar una estimación de la velocidad del vehículo con alta exactitud. El VUAE se ha contrastado con un sistema de velocidad de referencia, basado en cables piezoeléctricos.Peer reviewe

On the Unification of Process Semantics: Logical Semantics

We continue with the task of obtaining a unifying view of process semantics by considering in this case the logical characterization of the semantics. We start by considering the classic linear time-branching time spectrum developed by R.J. van Glabbeek. He provided a logical characterization of most of the semantics in his spectrum but, without following a unique pattern. In this paper, we present a uniform logical characterization of all the semantics in the enlarged spectrum. The common structure of the formulas that constitute all the corresponding logics gives us a much clearer picture of the spectrum, clarifying the relations between the different semantics, and allows us to develop generic proofs of some general properties of the semantics.Comment: In Proceedings SOS 2011, arXiv:1108.279

Numerical Simulation of Electric Currents through Insulating Materials

A numerical simulation of electric currents is carried out through solid dielectrics from a model based on the local polarization. A degradation of material was considered to be produced from one of the electrodes and we simulated it by admitting modifications in the chemical structure of the material, which implies an alteration in the value of the corresponding dipole moments that characterize the material, as well as the concentration of the latest. Different simulations are achieved according to the ratio of the degraded thickness and the temperature