Magnetic energy harvesting and concentration at distance by transformation optics

Magnetic energy is one the main agents powering our society: generating energy in power plants, keeping information in magnetic memories, moving our devices with motors. All of these applications require a certain spatial distribution of magnetic energy, for example concentrating it in a transformer core or in a magnetic sensor. We introduce in this work a way to collect magnetic energy and distribute it in space with unprecedented efficiency and flexibility, allowing very large concentration of magnetic energy in a free space region, an enhanced magnetic coupling between two magnetic sources, and the transfer of magnetic energy from a source to a given distant point separated by empty space. All these features are achieved with a single device, a magnetic shell designed by transformation optics.Comment: 15 pages, 5 figure

An assessment of the sea breeze energy potential using small wind turbines in peri-urban coastal areas

From wind speed data recorded hourly at 2 m high during 18 years (1993-2010) in the Llobregat Delta (15 km south of Barcelona city; northeast of the Iberian Peninsula), wind speed distributions at 10 m high were computed for the whole year and for the sea breeze period (from March 1 to September 30, from 10 to 19 local time). Weibull probability density functions fitted to the distributions were used to assess the wind energy generated by two off-grid small wind turbines: the IT-PE-100 and the HP-600W. Results from FAST and AeroDyn simulation tools were compared with those obtained by applying measured wind speeds to manufacturer power curves. Using manufacturer data, the IT-PE-100 would deliver 132 kWh during the whole year (70 kWh during the sea breeze period). From the simulations, the IT-PE-100 would deliver 155 kWh during the whole year (80 kWh during the sea breeze period). It is concluded that the sea-breeze is an interesting wind energy resource for micro-generation, not only in the Mediterranean basin but in other areas of the world with similar wind regimes, and particularly in peri-urban coastal areas where large-scale wind farms cannot be implemented.Peer ReviewedPostprint (published version

Antimagnets: Controlling magnetic fields with superconductor-metamaterial hybrids

Magnetism is very important in science and technology, from magnetic recording to energy generation to trapping cold atoms. Physicists have managed to master magnetism - to create and manipulate magnetic fields- almost at will. Surprisingly, there is at least one property which until now has been elusive: how to 'switch off' the magnetic interaction of a magnetic material with existing magnetic fields without modifying them. Here we introduce the antimagnet, a design to conceal the magnetic response of a given volume from its exterior, without altering the external magnetic fields, somehow analogous to the recent theoretical proposals for cloaking electromagnetic waves with metamaterials. However, different from these devices requiring extreme material properties, our device is feasible and needs only two kinds of available materials: superconductors and isotropic magnetic materials. Antimagnets may have applications in magnetic-based medical techniques such as MRI or in reducing the magnetic signature of vessels or planes.Comment: 14 pages, 4 figure

Experimental realization of magnetic energy concentration and transmission at a distance by metamaterials

Concentrating magnetic energy in a desired volume is an important requirement for many technologies. Here, we experimentally realize a superconductor-ferromagnetic metamaterial that allows to concentrate the magnetostatic energy in its interior and in other situations to amplify the energy in its exterior. We show that surrounding two distant current loops with two such metamaterials enhance the magnetostatic coupling between them. We also demonstrate that a ferromagnetic-only metamaterial, without superconducting parts, achieves these properties with only a slight decrease in performance. Results may be applied to increase the sensitivity of magnetic sensors or for enhancing wireless power transmission, where efficiency depends critically on the magnetic coupling strength between source and receiver

Embodied Artificial Intelligence through Distributed Adaptive Control: An Integrated Framework

In this paper, we argue that the future of Artificial Intelligence research resides in two keywords: integration and embodiment. We support this claim by analyzing the recent advances of the field. Regarding integration, we note that the most impactful recent contributions have been made possible through the integration of recent Machine Learning methods (based in particular on Deep Learning and Recurrent Neural Networks) with more traditional ones (e.g. Monte-Carlo tree search, goal babbling exploration or addressable memory systems). Regarding embodiment, we note that the traditional benchmark tasks (e.g. visual classification or board games) are becoming obsolete as state-of-the-art learning algorithms approach or even surpass human performance in most of them, having recently encouraged the development of first-person 3D game platforms embedding realistic physics. Building upon this analysis, we first propose an embodied cognitive architecture integrating heterogenous sub-fields of Artificial Intelligence into a unified framework. We demonstrate the utility of our approach by showing how major contributions of the field can be expressed within the proposed framework. We then claim that benchmarking environments need to reproduce ecologically-valid conditions for bootstrapping the acquisition of increasingly complex cognitive skills through the concept of a cognitive arms race between embodied agents.Comment: Updated version of the paper accepted to the ICDL-Epirob 2017 conference (Lisbon, Portugal

Benchmarking Methods for Audio-Visual Recognition Using Tiny Training Sets

International audienceThe problem of choosing a classifier for audio-visual command recognition is addressed. Because such commands are culture- and user-dependant, methods need to learn new commands from a few examples. We benchmark three state-of-the-art discriminative classifiers based on bag of words and SVM. The comparison is made on monocular and monaural recordings of a publicly available dataset. We seek for the best trade off between speed, robustness and size of the training set. In the light of over 150,000 experiments, we conclude that this is a promising direction of work towards a flexible methodology that must be easily adaptable to a large variety of users

Evaluation of Gender-Related Digital Violence Training in Catalonia

This study examines the results of evaluating a Catalan training program for practitioners working with survivors of gender-related violence. Considering the lack of scientific evidence previously shown by studies on this topic, this article aimed to triangulate the participants’ self-perception with their assessment of knowledge and competencies in tackling digital gender-related violence before and after the training. To do so, a pre-test and post-test case-based design was employed to identify and measure the participants’ improvement in self-perceived knowledge and their effective gain in knowledge and skills to address this kind of violence. Considering the contributions of a feminist evaluation approach, we also included in our evaluation the analysis of classroom interactions and the participants’ responses. The results overall demonstrate that the incorporation of assessment criteria from the feminist evaluation methodology increased the reliability of evaluation criteria. In addition, it also enabled us to identify the need to continue developing training programs that empower participants and prevent women and LGBTQI+ people from disengaging from digital spaces

Algunos datos edáficos del yacimiento arqueológico de Aparrea (Navarra)

Por encargo de Dra. A. Castiella del departamento de Arqueología de la Universidad de Navarra, se hicieron una serie de estudios analíticos (granulometría, pH, carbonatos, materia orgánica y fósforo) sobre 14 muestras de una serie de "hoyos" de un yacimiento arqueológico situado en Biurrun (Navarra). Por diferentes motivos los resultados de estos parámetros tuvieron un escaso poder discriminante para significar diferencias substanciales entre las diferentes muestras. Paralelamente se realizaron por el mismo Departamento de Química y Edafología observaciones macro- y mesoscópicas de la estructura de las muestras lo cual ha permitido establecer una serie de hipótesis en cuanto al origen y manipulación de dichas estructuras arqueológicas. Dichos resultados se exponen a continuación