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Preisach modelling of nonlinear response in electrically biased lead zirconate titanate-based piezoceramics

  • Ochoa Guerrero, Diego A.
  • Perez, Rafael A.
  • García García, José Eduardo
The alteration of the high-field electrical permittivity (nonlinear response) of PZT-based ceramics when an electrical bias field is applied is reported in this work. Large differences are observed between soft and hard PZT behaviours. While in soft PZT a bias field does not modify the nonlinear behaviour, a notable dependence is verified in hard PZT. The Preisach model is satisfactorily used to describe experimental results. A distribution function containing the first terms of the Maclaurin development series of a function composed by two Gaussian-like functions of different amplitudes is proposed. The model gives a satisfactory explanation for the fact that the permittivity depends not only on the amplitude of the applied electric field, but also on the bias field, both for soft and hard ceramics and for poled or unpoled samples.
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Producció científica del Campus del Baix Llobregat. Desembre 2012

  • Universitat Politècnica de Catalunya. Campus del Baix Llobregat. Biblioteca
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Method for forming a magnec field of arbitrary shape from an established template

  • Torrents Dolz, Josep M.
  • Juan García, Pablo
  • Sánchez Moragues, Miguel Ángel
A strategy to design a particular form of magnetic field along an axis from a coaxial inductor is described. The procedure is illustrated with the design of a constant magnetic field inside a cubic inductor. It validates the goodness of the method by comparing the results with all possible combinations of inductance within a limited set of solutions. Keywords: Magnetic field, magnetic sensor, Helmholtz coils., Peer Reviewed
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Classification of sperm whale clicks (Physeter macrocephalus) with Gaussian-kernel based networks

  • Van der Schaar, Mike Connor Roger Malcolm
  • Delory, Eric
  • André, Michel
With the aim of classifying sperm whales, this report compares two methods that can use Gaussian functions, a radial basis function network, and support vector machines which were trained with two different approaches known as C-SVM and º-SVM. The methods were tested on data recordings from seven different male sperm whales, six containing single click trains and the seventh containing a complete dive. Both types of classifiers could distinguish between the clicks of the seven different whales, but the SVM seemed to have better generalisation towards unknown data, at the cost of needing more information and slower performance.
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Dynamic sensation of comfort in buildings : the temperature changes effects

  • Palme, M
  • Isalgué Buxeda, Antonio
  • Coch Roura, Helena
  • Serra Florensa, Rafael
  • Marincic, I
  • Fanchiotti, A
The sensation of comfort in buildings depends on exter¬nal and internal variables: the well-known PMV method relates the expected temperature with the physiological behavior of the human body. Some models have discus¬sed the relevance of adaptation factors, in order to ex¬plain the higher expected “good” temperature of users living in warm climates. The same PMV method has been modified for these climatic situations. An adapta¬tion term has clearly to be considered, but other effects are important to determine the real expected temperatu¬re. In this paper temperature changes are considered to play an important role determining the expected “good” temperature. Effects of ventilation, rapid thermal chan¬ges when people move inside or outside of a building, continuous change in the temperature rate in the HVAC controlled spaces, are investigated here. Results show how to determine a dT/dt dependent term, which has to be considering in the PMV evaluation, in warm as in temperate climate. These results will be com¬pared with field studies for different climates. A PID (pro¬portional integrative derivative) correction in the PMV predict results seem to have to be expected, to consider at the same time adaptation and temperature rate effects.
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Regional foods consumption patterns in the EU

  • Gil Roig, José María
  • Gracia Royoz, Azucena
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Reducción en la utilización de compuestos orgánicos volátiles en la industria del curtido

  • Solà, Anna
  • Cuadros Domènech, Rosa Maria
  • Ollé Otero, Lluís
  • Bacardit Dalmases, Anna
La curtición es una actividad industrial de larga tradición en Catalunya, que desde unos inicios totalmente artesanales ha ido evolucionando progresivamente. El proceso de curtido se basa en realizar sobre la piel en bruto una serie de tratamientos químicos y mecánicos que permitan parar el proceso de descomposición natural de los tejidos, estabilizarlo químicamente y proporcionarle unas propiedades físicas para que sea apta para los usos a los cuales irá destinada, como pueden ser confección, calzado, marroquinería, tapicería, etc. En la industria del curtido se utilizan algunos productos químicos contaminantes, peligrosos y tóxicos. Este trabajo pretende ser una pequeña aportación a la investigación para la reducción o substitución de una parte de estos productos por otros menos peligrosos y menos contaminantes utilizados en la parte de acabados. En este trabajo se ha estudiado como reducir los disolventes de una formulación de acabados que actualmente se está utilizando en la producción de un artículo en una industria del sector. En concreto, se ha realizado un estudio de cada capa de forma que se puedan sustituir los productos más contaminantes y a la vez, que se obtengan todas las prestaciones físicas y organolépticas necesarias para el artículo a fabricar. Se ha fabricado una piel con el proceso nuevo y se ha comparado con el proceso convencional. Se ha comprobado que con la nueva formulación se cumplan todos los requisitos de resistencias físicas, de solideces, y propiedades organolépticas. También se ha estudiado la disminución de compuestos orgánicos volátiles obtenida con la nueva formulación.
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A survey on M2M systems for mHealth: a wireless communications perspective

  • Kartsakli, Elli
  • Lalos, Aristeidis
  • Antonopoulos, Angelos
  • Tennina, Stefano
  • Di Renzo, Marco
  • Alonso Zárate, Luis Gonzaga
  • Verikoukis, Christos
In the new era of connectivity, marked by the explosive number of wireless electronic devices and the need for smart and pervasive applications, Machine-to-Machine (M2M) communications are an emerging technology that enables the seamless device interconnection without the need of human interaction. The use of M2M technology can bring to life a wide range of mHealth applications, with considerable benefits for both patients and healthcare providers. Many technological challenges have to be met, however, to ensure the widespread adoption of mHealth solutions in the future. In this context, we aim to provide a comprehensive survey on M2M systems for mHealth applications from a wireless communication perspective. An end-to-end holistic approach is adopted, focusing on different communication aspects of the M2M architecture. Hence, we first provide a systematic review of Wireless Body Area Networks (WBANs), which constitute the enabling technology at the patient's side, and then discuss end-to-end solutions that involve the design and implementation of practical mHealth applications. We close the survey by identifying challenges and open research issues, thus paving the way for future research opportunities., Peer Reviewed
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Deep Reinforcement Learning for Autonomous Collision Avoidance

  • Liberal Huarte, Jon
La prevenció de col·lisions és una tasca complexa en el control de vehicles autònoms. Els mètodes tradicionals utilitzen models explícits per predir la dinàmica dels vehicles i intentar anticipar les decisions de control dels conductors en l'entorn. Aquests models no sempre aconsegueixen predir amb èxit la trajectòria dels obstacles dinàmics a l'entorn de el vehicle controlat. Aquesta tesi investiga un mètode de control basat en l'aprenentatge profund per reforç. L'agent processa les distàncies detectades des del vehicle controlat als objectes més propers, i mitjançant xarxes neuronals estima l'acció de control òptima per evitar col·lisions. Per a l'aprenentatge, es dissenya un simulador de trànsit que genera un ampli rang de carreteres i vehicles, que interactuen - no sempre seguint les normes de circulació - amb el vehicle de control, el que permet a l'agent demanar informació diversa i associar a cada estat una acció de control que minimitzi el risc de col·lisió. Després de l'entrenament, l'agent demostra haver après a evitar circular en àrees amb alta densitat de trànsit, a adaptar la seva velocitat per evitar col·lisions frontals i posteriors, i a realitzar girs que evitin xocs amb vehicles que s'aproximen pels laterals., La prevención de colisiones es una tarea compleja en el control de vehículos autónomos. Los métodos tradicionales utilizan modelos explícitos para predecir la dinámica de los vehículos e intentar anticipar las decisiones de control de los conductores en el entorno. Estos modelos no siempre consiguen predecir con éxito la trayectoria de los objectos dinámicos en el entorno del vehículo controlado. Esta tesis investiga un método de control basado en el aprendizaje profundo por refuerzo. El agente procesa las distancias detectadas desde el vehículo controlado a los objectos más cercanos, y mediante redes neuronales estima la acción de control óptima para evitar colisiones. Para el aprendizaje, se diseña un simulador de tráfico que genera un amplio rango de carreteras y vehículos, que interactúan - no siempre siguiendo las normas de circulación - con el vehículo de control, lo que permite al agente recabar información diversa y asociar a cada estado una acción de control que minimice el riesgo de colisión. Tras el entrenamiento, el agente demuestra haber aprendido a evitar circular en áreas con alta densidad de tráfico, a adaptar su velocidad para evitar colisiones frontales y traseras, y a realizar giros que eviten choques con vehículos que se aproximan por los laterales., Collision avoidance is a complicated task for autonomous vehicle control. Most traditional methods in this area consist on model-based solutions, where an understanding of vehicle dynamics and an accurate model of vehicle behavior is required, in order to predict the trajectory of the controlled car and the surrounding vehicles. Such solutions struggle to anticipate and explicitly model surrounding car driving behavior. This work investigates a model-free Deep Reinforcement Learning based method for collision avoidance, where the agent processes the distances to the closest entities and outputs the steering angle and acceleration required to avoid collisions. A traffic simulator is used to generate a wide range of roads and vehicles, which will interact - not always compliantly - with the learning agent allowing it to collect learning experience. After being trained on such conditions, the agent shows intelligent driving behavior, avoiding areas with high traffic density, adapting its speed to avoid rear or front crashes, and steering when necessary to avoid lateral crashes., Outgoing
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Tools for validation of the Lightning Imager sensor on the 3rd generation of the METEOSAT weather satellite

  • Partal Camps, Maria Núria
The 3rd generation of the METEOSAT (MTG) will be equipped with a lightning imager sensor (LI) to detect and locate lightning flashes. The field-of-view of the LI-MTG will cover Europe and Africa. Since the LI-MTG will observe optical emissions from lightning from cloud tops, it will be able to provide total lightning activity in thunderstorms including intra-cloud and cloud-to-ground. At ground, the unique system that detects total lightning with high efficiency is the Lightning Mapping Array (LMA). The UPC Lightning Research Group operates the Ebro LMA network at the Delta de l’Ebre area. This network will be used to validate the MTG LI performance when it will be in operation. To do that, the UPC LRG group has recently compared the ISS-LIS imager sensor on the International Space Station and the needs have been defined. The aim of this project is to follow the comparison between the ISS-LIS imager and LMA to define the needs for LI-MGT. To do that, data from the Geostationary Lightning Mapper (GLM) will be compared with the Colombia LMA at Barrancabermeja, as both LI-MGT and GLM are geostationary satellites. With the results obtained the bases for the final validation tool of MTG LI will be set and also will be reached a better understanding of the data gathered by a lightning detection system on board of a geostationary satellite.
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