Des réseaux multilatéraux, en appui aux études littéraires et culturelles francophones à l’université

Cette réflexion présente les dispositifs mis en place par l’Agence universitaire de la francophonie, dont le principe fondateur est de créer des réseaux afin de permettre, dans une perspective de solidarité, l’échange d’informations et de moyens. Ces réseaux, par la diversité des situations et des disciplines d’enseignement et de recherche qu'ils mettent en relation, se positionnent dans le développement de nouveaux savoirs

An improved topology for reconfigurable CPSS-based reflectarray cell,

International audienceAn improved topology of a CPSS-based unit-cell is proposed as a building block of reconfigurable dual-CP reflectarrays in X-band. Its performance is first studied numerically under oblique incidence. Then, we show that it is possible to reduce significantly the number of active components needed to reconfigure the unit-cell, thus leading to an easier implementatio

Cellule déphaseuse en bipolarisation circulaire pour antenne à réseau réflecteur

National audienceUne nouvelle cellule unitaire pour une antenne à réseau réflecteur reconfigurable en bipolarisation circulaire est proposée. Elle permet d'obtenir une résolution en phase d'environ 2 bits en réflexion pour les deux ondes incidentes en polarisation circulaire (droite et gauche). La cellule est étudiée et mesurée à 8,4 GHz et offre expérimentalement une bande passante de 320 MHz

Design and Characterization of a CPSS-based Unit-Cell for Circularly Polarized Reflectarray Applications

International audienceA CPSS-based unit-cell is proposed as a building block of future reconfigurable dual-CP reflectarrays illuminated by a dual CP primary feed. It is based on an enhanced version of the original Pierrot's cell with multiple wires bent in a crank-like shape. It provides a 2-bit phase resolution in reflection for the left hand circular polarization (LHCP) and is nearly transparent in right hand circular polarization (RHCP). The main design steps and measurement procedure of the optimized cell are described in detail. The simulated and measured characteristics are in good agreement. The experimental results demonstrate a 6.4% bandwidth for a phase resolution better than 1.9bits and an insertion loss of 0.5dB at resonance

Design of a CPSS-based reflectarray cell with controllable reflected phase for dual-circularly-polarised reflectarrays

International audienceA first step towards the design of dual-circularly polarised reflectarrays with independent control of both polarisations is proposed in X-band. A reconfigurable unit-cell based on a circularly- polarised selective surface is studied at 8.5 GHz. It provides a 2-bit phase resolution in reflection for the left hand circular polarisation (LHCP) and is nearly transparent in right hand circular polarisation (RHCP). The simulated characteristics are excellent over a 6.4% bandwidth. The proposed unit-cell is fabricated using stacked substrates. A loss budget demonstrates that loss is quite balanced between loss in materials and polarisation conversion. Then, a study of the effect of realistic switches is shown in order to demonstrate that conventional p.i.n. diodes would cause an acceptable loss increase

Optokinetic stimulation rehabilitation in preventing seasickness

SummaryObjectivesSeasickness occurs when traveling on a boat: symptoms such as vomiting are very disturbing and may be responsible for discontinuing travel or occupation and can become life-threatening. The failure of classical treatment to prevent seasickness has motivated this retrospective study exploring optokinetic stimulation in reducing these symptoms.Patients and methodsExperimental training of 75 sailors with optokinetic stimulation attempted to reduce seasickness manifestations and determine the factors that could predict accommodation problems.ResultsEighty percent of the trained subjects were able to return on board. No predictive factors such as sex, occupation, degree of illness, number of treatment sessions, time to follow-up, and age were found to influence training efficacy.ConclusionOptokinetic stimulation appears to be promising in the treatment of seasickness. Nevertheless, statistically significant results have yet to demonstrate its efficacy