Voltage controlled metamaterial

International audienceA tunable metamaterial based on conducting coils loaded by an electronic circuit containing a varicap diode has been demonstrated. The agility exceeds one octave inside the 100-500 MHz range. Permeability levels are significantly increased when the loop is loaded by a proper magnetic material. A model gives a good desription of the observed permeability spectra

Anchor-Based Localization Using Distributed Interval Contractors

This paper presents a new method to solve anchor-based distributed localization problems. This method is based on a generic algorithm using interval contractors. In the theoretical part, we detail a new formalism for distributed contractors. This formalism is used to demonstrate that our distributed algorithm converges to the same fixed point than the centralized algorithm. Then, we use this distributed algorithm to solve an anchor-based distributed localization problem in a Wireless Sensor Network (WSN)

Microwave properties of diluted composites made of magnetic wires with giant magneto impedance effect

International audienceIn this paper, the theoretical description of wire media made of magnetic wires. We show that there is a close link between the Giant Magneto Impedence effect (GMI) in individual wires, and free-space microwave properties of the composite wire media. The demonstration with tunable dielectric constant under a static magnetic field

An Arduino compatible CAN Bus architecture for sailing applications

International audienceThis paper describes a Controller Area Network (CAN) Bus architecture based on Arduino compatible boards, to be used as an alternative communication system for robotic applications. This combines both, the robustness of CAN and the accessibility of Arduino software. The architecture is developed here to improve a Navigational Assistance System, which was initially created for disabled people. The system is composed of Arduino compatible boards, wired with various sensors and actuators, and communicating with an Human Machine Interface (HMI), directly accessible via a mobile phone or a tablet running on the open-source operating system Android. Information is transferred through the CAN bus architecture between multiple nodes (i.e. Arduino compatible boards) and the implementation of a CAN bootloader allows the reconfiguration of the nodes directly through the bus. The aim is to create a generic system able to work in various kinds of situations, adaptable to all kinds of users, including persons with all sorts of disabilities. This work will result in a demonstrator on a Miniji for the WRSC 2013 and an entirely joystick controlled boat for single handed sailing

Effect of the magnetic properties of the inclusions on the high-frequency dielectric response of diluted composites

International audienceThe high-frequency permittivity of composites consisting of a lattice of ferromagnetic wires is investigated. Experimental results using free space or coaxial line microwave measurements are reported. It is shown that the dielectric response is strongly dependent on the magnetic properties of the wires. Negative real permittivity is observed over a wide frequency range for wires with circumferential magnetization, while a resonant behavior is observed on wires with an axially magnetized core. In addition, it is shown that a moderate external field can induce large changes in the dielectric response. We prove that the underlying physics of these composites made of oriented magnetic wires is basically the same as the giant magnetoimpedance (GMI) effect. A model based on GMI equations is proposed which predicts this unusual dielectric phenomenon

The disabled set sail

International audienceSailing is not an activity that can easily be done with a handicap. Sailors typically need mobility to steer a boat. An Arduino-compatible CAN architecture for sailing applications is set to change that

Système d'assistance à la navigation handivoile

International audienceCe projet, fruit d'une collaboration entre l'ENSTA-Bretagne et l'entreprise Splashelec vise à développer une Interface Homme-Machine (IHM) qui facilite la navigation par le biais de capteurs et d'un boîtier de commandes embarqué sur le bateau. Il se concrétise par la création d'une interface graphique directement accessible via un téléphone mobile pour pallier le manque de mobilité du navigateur

A CUPID Li2100MoO4scintillating bolometer tested in the CROSS underground facility

A scintillating bolometer based on a large cubic Li2100MoO4 crystal (45 mm side) and a Ge wafer (scintillation detector) has been operated in the CROSS cryogenic facility at the Canfranc underground laboratory in Spain. The dual-readout detector is a prototype of the technology that will be used in the next-generation 0¿2ß experiment CUPID . The measurements were performed at 18 and 12 mK temperature in a pulse tube dilution refrigerator. This setup utilizes the same technology as the CUORE cryostat that will host CUPID and so represents an accurate estimation of the expected performance. The Li2100MoO4 bolometer shows a high energy resolution of 6 keV FWHM at the 2615 keV ¿ line. The detection of scintillation light for each event triggered by the Li2100MoO4 bolometer allowed for a full separation (~8s) between ¿(ß) and a events above 2 MeV . The Li2100MoO4 crystal also shows a high internal radiopurity with 228Th and 226Ra activities of less than 3 and 8 µBq/kg, respectively. Taking also into account the advantage of a more compact and massive detector array, which can be made of cubic-shaped crystals (compared to the cylindrical ones), this test demonstrates the great potential of cubic Li2100MoO4 scintillating bolometers for high-sensitivity searches for the 100Mo 0¿2ß decay in CROSS and CUPID projects

Actes du VIIIème colloque Questions de Pédagogie dans l'Enseignement Supérieur : Innover : Comment ? Pourquoi ?

International audienc

Métamatériaux à base d'éléments ferromagnétiques et électroniques

Rapporteurs : D. LIPPENS et A. de LustracMetamaterials based on ferromagnetic and electronic elements are made, characterized and modelized. In the first part, a bound on the absorption of chiral media is found. The second part focuses on the study of the artificial permeability of composites made of loaded loops and helices. Experimental evidence of a voltage controlled artificial permeability is given. A model based on impedance measurements is found to be in good aggreemeent with experimental works. The last part of this thesis demonstrates the possibility to adjust the artifical permittivity of a ferromagnetic wires lattice with a static magnetic field.Des métamatériaux homogénéisables à base d'éléments ferromagnétiques et électroniques sont fabriqués, mesurés et modélisés dans le domaine des hyperfréquences. Ces métamatériaux sont des composites artificiels structurés, hétérogènes et parfois multi-échelles à base d'inclusions diélectriques et métalliques, qui présentent des permittivités et des perméabilités artificielles. Dans un premier temps, l'´elaboration d'un critère intégral pour les métamatériaux chiraux permet de cerner les limites en absorption de ces composites. Dans un deuxième temps, l'étude se concentre sur les composites à perméabilité artificielle à base de boucles ou d'hélices métalliques chargées par des composants électroniques actifs ou passifs. Un modèle de perméabilité effective, fondé sur la mesure d'impédance de la charge est proposé.Les boucles peuvent être chargées par des diodes varicap. La perméabilité artificielle est alors ajustable par une tension électrique. Dans ce cas, il est possible de fabriquer un métamatériau actif à bande passante reconfigurable instantanément. Enfin, la dernière partie de cette thèse explore les réseaux de fils métalliques. En utilisant des fils ferromagnétiques, un nouveau comportement diélectrique artificiel est mis en exergue : la permittivité varie sous l'effet d'un champ magnétique. Aprs avoir mis en évidence le phénomène lors d'une étude expérimentale, la modélisation montre que la magnéto-impédance géante est à l'origine du comportement résonant en basses fréquences des réseaux de fils ferromagnétiques