Robust stability analysis of formation control in local frames under time-varying delays and actuator faults

This paper investigates the robust stability of a multiagent system moving to a desired rigid formation in presence of unknown time-varying communication delays and actuator faults. Each agent uses relative position measurements to implement the proposed control method, which does not require common coordinate references. However, the presence of time delays in the measurements, which is inherent to the communication links between agents, has a negative impact in the control system performance leading, in some cases, to instability. Furthermore, the robust stability analysis becomes more complex if failures on actuators are taken into account. In addition, delays may be subject to time variations, depending on network load, availability of communication resources, dynamic routing protocols, or other environmental conditions. To cope with these problems, a sufficient condition based on Linear Matrix Inequalities (LMI) is provided to ensure the robust asymptotic convergence of the agents to the desired formation. This condition is valid for any arbitrarily fast time-varying delays and actuator faults, given a worst-case point-to-point delay. Finally, simulation results show the performance of the proposed approach

Mitigation of modulation instability in Brillouin distributed fiber sensors by using orthogonal polarization pulses

A technique based on the use of orthogonally-polarized pulses is proposed to mitigate the detrimental impact of modulation instability on Brillouin distributed fiber sensors. While the theoretical underpinnings of the method are described by introducing a detailed model for the vector modulation instability, the technique is experimentally validated in a 25-km sensing link. Numerical and experimental results demonstrate that the use of orthogonally-polarized pulses not only mitigates the impact of modulation instability, but also the four-wave mixing occurring in systems using pumps with parallel polarization; thus, providing an important sensing range enhancement with a reduced pump depletion.J. Urricelqui, M. Sagues and A. Loayssa acknowledge the support from the Spanish Ministerio de Economia y Competitividad through the project TEC2013-47264-C2-2-R, FEDER funds and Universidad Pública de Navarra

Intra-varietal diversity for agronomic traits in 'Garnacha Blanca'

'Garnacha Blanca' is a somatic variant derived from 'Garnacha Tinta', an old variety with large genetic and phenotypic variability. In this work we have studied for two years the phenotypic variation existing in 'Garnacha Blanca' for yield and quality related traits in accessions from 14 sampling locations of ancient vineyards in the Ebro Valley, Spain. The results showed high variability among the accessions in many of the traits studied in 'Garnacha Blanca'. Different accessions could be distinguished both years using several traits, including two important traits in terms of quality and yield: bunch compactness and yield per plant. A large environment effect, intrinsic to the 'Garnacha' group, enhances phenotypic variation among years, what requires increasing the number of bunches and years for clonal characterization in this variety. The dimensions of the berry showed the least variability, while traits related to bunch architecture like bunch length were discriminant and also stable

High-speed railway tunnel monitoring using point, long gauge and distributed strain and temperature fiber optic sensors

La monitorización de estructuras es una rama de la ingeniería estructural que está captando mucha atención actualmente. Las deformaciones y temperaturas son, habitualmente, los parámetros monitorizados porque son los que mejor representan el comportamiento estructural. De todos los tipos de sensores existentes, los basados en fibra óptica resultan especialmente interesantes debido a sus ventajas comparativas sobre los sensores convencionales. En este artículo se presentan los trabajos de monitorización de la estructura de un túnel artificial de Alta Velocidad construido en Mogente (España) mediante tres tipos de sensores ópticos desarrollados por los autores. Los resultados de los sensores se comparan con los proporcionados por un modelo teórico de elementos finitos. Esta comparación confirma que los sensores reproducen notablemente bien la pauta general de comportamiento de la estructura, incluso con pequeños niveles de deformación (5µε). Por último, el artículo discute el comportamiento de los sensores, sus mediciones y sus campos de aplicación.Structural Health Monitoring (SHM) is presently having a great development. Strains and temperatures are usually the key parameters to be monitored due to their relevance when explaining structural behavior. Several types of sensors are used in SHM, but fiber optic sensors are especially interesting due to their advantages with respect to conventional sensors. In this paper, the monitoring of a high-speed train tunnel recently built in Spain using three types of fiber optic sensors developed by the authors is shown. Results given by the sensors are compared to those provided by a theoretical model built using FEM. Comparison of measurements and theoretical results confirms that the sensors reproduced remarkably well the general patterns of the tunnel structural behavior, even when strains are relatively small (around 5 µε). Finally, the paper discusses the behavior of the sensors, their measurements and their field of application which is useful for researchers and practitioners.Los autores quieren agradecer a la Universitat Politècnica de València, al Ministerio de Educación por la financiación recibida a través del proyecto BIA2011-27104 y al Ministerio de Fomento por el apoyo recibido a través del Proyecto SOPROMAC (P41/08)

The steel–concrete interface

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made

VIII Encuentro de Docentes e Investigadores en Historia del Diseño, la Arquitectura y la Ciudad

Acta de congresoLa conmemoración de los cien años de la Reforma Universitaria de 1918 se presentó como una ocasión propicia para debatir el rol de la historia, la teoría y la crítica en la formación y en la práctica profesional de diseñadores, arquitectos y urbanistas. En ese marco el VIII Encuentro de Docentes e Investigadores en Historia del Diseño, la Arquitectura y la Ciudad constituyó un espacio de intercambio y reflexión cuya realización ha sido posible gracias a la colaboración entre Facultades de Arquitectura, Urbanismo y Diseño de la Universidad Nacional y la Facultad de Arquitectura de la Universidad Católica de Córdoba, contando además con la activa participación de mayoría de las Facultades, Centros e Institutos de Historia de la Arquitectura del país y la región. Orientado en su convocatoria tanto a docentes como a estudiantes de Arquitectura y Diseño Industrial de todos los niveles de la FAUD-UNC promovió el debate de ideas a partir de experiencias concretas en instancias tales como mesas temáticas de carácter interdisciplinario, que adoptaron la modalidad de presentación de ponencias, entre otras actividades. En el ámbito de VIII Encuentro, desarrollado en la sede Ciudad Universitaria de Córdoba, se desplegaron numerosas posiciones sobre la enseñanza, la investigación y la formación en historia, teoría y crítica del diseño, la arquitectura y la ciudad; sumándose el aporte realizado a través de sus respectivas conferencias de Ana Clarisa Agüero, Bibiana Cicutti, Fernando Aliata y Alberto Petrina. El conjunto de ponencias que se publican en este Repositorio de la UNC son el resultado de dos intensas jornadas de exposiciones, cuyos contenidos han posibilitado actualizar viejos dilemas y promover nuevos debates. El evento recibió el apoyo de las autoridades de la FAUD-UNC, en especial de la Secretaría de Investigación y de la Biblioteca de nuestra casa, como así también de la Facultad de Arquitectura de la UCC; va para todos ellos un especial agradecimiento