39 research outputs found
Radiofrequency and mechanical tests of silver coated CuCrZr contacts for the ITER ion cyclotron antenna
The ITER Ion Cyclotron Resonance Heating (ICRH) system is designed to couple to the plasma 20âŻMW of RF power from two antennas in the 40â55âŻMHz frequency range during long pulses of up to 3600âŻs and under various plasma conditions with Edge Localized Modes. Radio-Frequency (RF) contacts are integrated within the ITER ICRH launcher in order to ensure the RF current continuity and ease the mechanical assembly by allowing the free thermal expansion of the Removable Vacuum Transmission Line coaxial conductors during RF operations or during 250âŻÂ°C baking phases. A material study has been carried out to determine which materials and associated coatings are relevant for RF contacts application in ITER. In parallel, RF tests have been performed with a new prototype of Multi-ContactÂź LA-CUT/0,25/0 contacts made of silver-coated CuCrZr louvers. During these tests on a RF vacuum resonator, currents between 1.2 kA and 1.3 kA peak have been reached a few tens of times in steady-state conditions without any visible damage on the louvers. A final 62âŻMHz pulse ending in a 300âŻs flat top at 1.9 kA resulted in severe damage to the contact. In addition, a test bed which performs sliding test cycles has been built in order to reproduce the wear of the contact prototype after 30 000 sliding cycles on a 3âŻmm stroke at 175âŻÂ°C under vacuum. The silver coating of the louvers is removed after approximately a hundred cycles whilst, to the contrary, damage to the CuCrZr louvers is relatively low
Immunogénicité des protéines p24 et gp 120 du VIH-1 adjuvantées par les nanoparticules de poly(acide lactique) et combinaison avec les vecteurs viraux
Notre objectif est d Ă©valuer la formulation et l immunogĂ©nicitĂ© en primo-vaccination/rappel d un nouveau vĂ©hicule de vaccination : les PLA poly(D,L-acide lactique). Ces nanoparticules synthĂ©tiques biodĂ©gradables prĂ©sentant des antigĂšnes adsorbĂ©s Ă leur surface, peuvent activer les deux bras de l immunitĂ©. Deux antigĂšnes VIH-1 gp120 et p24 peuvent ĂȘtre formulĂ©s sur la mĂȘme particule sans altĂ©rer la qualitĂ© et l intensitĂ© de la rĂ©ponse immune murine. Ces formulations n induisant pas de rĂ©ponse contre le vecteur vaccinal, la rĂ©ponse immune peut ĂȘtre amplifiĂ©e et maintenue par des rappels rĂ©pĂ©tĂ©s. Ces observations nous ont permis d Ă©valuer une stratĂ©gie vaccinale utilisant des PLA-p24, suivies d un rappel par un vecteur recombinant, poxvirus (rMVA), AdĂ©novirus (Ad5), ou de l ADN exprimant le mĂȘme antigĂšne. L association vecteur synthĂ©tique et vecteur viral permet d amplifier les rĂ©ponses humorales et cellulaires et semble une stratĂ©gie vaccinale prometteuse pour les infections chroniquesIn this study, the formulation and the immunogenicity of a new vaccine vehicle, the PLA poly(D,L-lactic acid), were evaluated in prime/boost strategy. These synthetic and biodegradable nanoparticles prepared with antigens adsorded on their surface, could induce both arms of immunity. Two antigens, HIV-1 p24 and gp120 could be formulated onto the same particle without modification of quality and intensity of immune responses in a mouse model. As these formulations induce no anti-vector immune responses, repeated boosting could increase and maintain immunity. Based on these observations, we evaluated a new vaccine strategy using PLA-p24 as a prime and recombinant vector (poxvirus (rMVA), Adenovirus (Ad5) or DNA) expressing the same antigen as a boost. Synthetic vector associated with viral vector is able to increase humoral and cellular immune responses, and seems a promising vaccine strategy against chronic infectionsLYON1-BU.Sciences (692662101) / SudocSudocFranceF
Reconnaissance de la Forme 3D et Estimation de la Profondeur Implémentation sur FPGA Spartan 3A d'un SoC pour la Vision 3D (Shape From Focus) Problématique Qu'est ce que un SystÚme de Vision 3D?
International audienceLe terme de « vision 3D » ou « de numérisation 3D », est apparu à la fin des années 1990, pour désigner des techniques d'acquisition de mesures tridimensionnelle sur des surfaces, techniques ayant la caractéristique de donner des nuages de points denses et importants dont l'ordre de grandeur est de quelques dizaines à plusieurs millions de points. Le nuage de points représente en fait l'information de l'image de profondeur et selon des différents traitements à l'image on peut aboutir à un ordre de précision de la reconstitution de l'objet ou scÚne en 3D. La vision 3D demeure une méthodologie de base pour réassurer le mécanisme de reconstitution des images tridimensionnelles. Outre les besoins en vision 3D de plus en plus gourmandes d'une spécificité dans son genre pour chaque application. Par conséquent, il faudra associée la problématique de chaque application à la meilleur technique apte à résoudre
Rétines à masques (utilisation de masques binaires pour l'implantation d'un opérateur de reconnaissance de forme dans une rétine CMOS)
Dans cette thÚse nous proposons une méthode permettant implantable dans une rétine CMOS pour reconnaßtre une forme ou un objet. Elle est basée sur une mesure de corrélation entre une image analysée et une image binaire (masque) mémorisée dans la rétine. Une premiÚre approche, basée sur un seuillage de l'image de l'objet à reconnaßtre, a donné d'intéressants résultats mais reste sensible à la position de l'objet analysé. Une deuxiÚme approche, utilisant le " dithering " pour générer le masque binaire, nous permet de mesurer la valeur des moments géométriques de l'image analysée, de déterminer la position de l'objet avant son analyse. Cette approche est innovante car elle conduit à une architecture de pixel simple et programmable. Les résultats obtenus ont été étendus à la mesure de moments de Legendre et de Zernike pour des applications de reconnaissance de formes et de compression d'images.In this thesis we propose a method that can be implemented in a CMOS retina for object or shape recognition. It is based on the measure of the correlation coefficient between the image under analysis and a binary image (mask) stored in memory devices in the retina. A first approach based on a simple thresholding of an image of the object to recognize has yielded interesting shape recognition results but it is sensitive to the position and orientation of the analyzed object. A second approach, using a dithering algorithm for, allows us to compute an estimated value of the geometrical moments of the analyzed image that are next used to determine the position of the object before its analysis. This approach is innovative since it is based on a novel, simple and programmable pixel architecture. Finally, the results obtained have been extended to the measurement of Legendre or Zernike moments for pattern recognition and image compression applications.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF
A New Method for Implementing Moment Functions in a CMOS Retina
International audienceWe present in this paper a new method for implementing geometric moment functions in a CMOS retina. The principle is based on the similarity between geometric moment equations and the measurement of the correlation value between an image to analyze and a range of grey levels. The latter is approximated by a binary image called mask using a dithering algorithm in order to reduce hardware implementation cost. The correlation product between the mask and the image under analysis gives an approximated value of the geometric moment with an error less than 1% of the exact value. Finally, the results obtained by our approach have been applied to an object localization application and the localization error due to the approximated moment values reported
Hardware Computation of Moment Functions in a Silicon Retina Using Binary Patterns
International audienceWe present in this paper a method for implementing moment functions in a CMOS retina for shape recognition applications. The method is based on the use of binary patterns and it allows the computation of different moment functions such geometric and Zernike moments of any orders by an adequate choice of the binary patterns. The advantages of the method over other methods described in the literature is that it is particularly suitable for the design of a programmable retina circuit where moment functions of different orders are obtained by simply loading the correct binary patterns into the memory devices implemented on the circuit. The moment values computed by the method are approximate values, but we have verified that in spite of the error the approximate values are significant enough to be applied to classical shape localization and shape representation and description applications
Using Dithering for Implementing Geometric Moment Function Estimation in a Correlation Retina
International audienceCorrelation retinas measure the correlation product of an image projected on a sensor by optical means and a function f(x, y) stored in the retina. This optical correlation is well suited for the measurement of geometric moments, and this is why one can find in the literature several correlation retina circuits dedicated to it. Unfortunately, these architectures are not programmable and are dedicated to specific applications. Moment functions are of great interest in pattern recognition. This application needs to compute, for example, geometric moments whose order can depend on the application. Thus, the implementation of this function in a correlation retina requires a flexible architecture where the function f(x, y) can be modified to allow the measurement of the product of the image under analysis and f(x, y). The most robust solution is to memorize f(x, y) in memory devices distributed in the array of pixels constituting the retina. But, for technological problems, it is necessary to limit the number of bits used to store f(x, y) in the sensor. In this article, we propose to use dithering algorithms to code f(x, y) on only one bit. We present herein the architecture of the retina circuit on which we are currently working and show that it is possible to obtain approximate geometric moment values with it
A CMOS Image Sensor Design for Speed Determination of Fast Moving Luminous Objects
International audienc
Masquer l'Objet pour Mieux le ReconnaĂźtre
National audienceLâĂ©volution des technologies de pointe a repoussĂ© les limites des domaines dâapplication de lâimagerie numĂ©rique de sorte que les capteurs dâimages sont aujourdâhui omniprĂ©sents dans beau- coup dâapplications, que ce soit des applications scientifiques ou des appli- cations liĂ©es au divertissement et Ă un usage grand public. Ces capteurs four- nissent en gĂ©nĂ©ral une image qui est par la suite traitĂ©e par un ordinateur ou des circuits Ă©lectroniques spĂ©cialisĂ©s. La course vers la miniaturisation et vers des systĂšmes autonomes compacts et lĂ©gers nĂ©cessite aujourdâhui des cap- teurs dâimages de plus en plus petits et de faible consommation. De plus, il existe des applications pour lesquelles il nâest pas indispensable dâavoir accĂšs Ă lâimage de la scĂšne observĂ©e. On peut alors envisager de remplacer une partie du capteur â celle qui est destinĂ©e Ă conditionner et sĂ©rialiser lâimage acquise pour la transmettre â par une Ă©lectronique de traitement permettant de sâaffranchir, partiellement ou totale- ment, de lâusage dâun ordinateur ou dâun circuit de traitement spĂ©cialisĂ©. De ce constat est nĂ© le concept de rĂ©tine Ă©lectronique ou rĂ©tine artificielle qui a fait lâobjet de nombreux travaux de recherche dans le monde entier depuis plus de quinze ans. Il peut ĂȘtre dĂ©fini commeuncircuitintĂ©grĂ©,unepuce,qui contient Ă la fois un capteur dâimages et des circuits Ă©lectroniques de traitement des images acquises afin de fournir, soit des images prĂ©traitĂ©es, soit des informa- tions caractĂ©ristiques des images