Annular interdigital transducer focuses piezoelectric surface waves to a single point

We propose and demonstrate experimentally the concept of the annular interdigital transducer that focuses acoustic waves on the surface of a piezoelectric material to a single, diffraction-limited, spot. The shape of the transducing fingers follows the wave surface. Experiments conducted on lithium niobate substrates evidence that the generated surface waves converge to the center of the transducer, producing a spot that shows a large concentration of acoustic energy. This concept is of practical significance to design new intense microacoustic sources, for instance for enhanced acouto-optical interactions

Modeled O 2 nightglow distributions in the Venusian atmosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96410/1/jgre3128.pd

Limiting absorption principle for the dissipative Helmholtz equation

Adapting Mourre's commutator method to the dissipative setting, we prove a limiting absorption principle for a class of abstract dissipative operators. A consequence is the resolvent estimates for the high frequency Helmholtz equation when trapped trajectories meet the set where the imaginary part of the potential is non-zero. We also give the resolvent estimates in Besov spaces

Skiroc: A Front-end Chip to Read Out the Imaging Silicon-Tungsten Calorimeter for ILC

Integration and low-power consumption of the read-out ASIC for the International Linear Collider (ILC) 82-millionchannel W-Si calorimeter must reach an unprecedented level as it will be embedded inside the detector. Uniformity and dynamic range performance has to reach the accuracy to achieve calorimetric measurement. A first step towards this goal has been a 10,000-channel physics prototype of 18*18 cm which is currently in test beam in CERN. A new version of a full integrated read out chip (SKIROC) has been designed to equip the technologic prototype to be built for 2009. Based on the running physics prototype ASIC (FLC_PHY3), it embeds most of the required features expected for the final detector. The dynamic range has been improved from 500 to 2000 MIP. An auto-trigger capability has been added allowing built-in zero suppress. The number of channel has been doubled reaching 36 to fit smaller silicon pads and the lownoise charge preamplifier now accepts both AC and DC coupled detectors. After an exhaustive description, the measurement results of that new front-end chip will be presented. The results on the technological R&D concurrently conducted on the ultra-thin PCB hosting both the front-end electronic and the silicon detectors will also be described

GAIA RVS data reduction : the 6^{th} dimension

International audienceThis poster describes the current organisation of RVS data processing among the Gaia-DPAC (Data Processing & Analysis Consortium), with a particular focus on the French community's contribution

Strain Gradient Plasticity Applied To Material Cutting

To better understand the complex phenomena involved in the cutting process is to better qualify the behaviour law used in the simulatiotrn of machining processes (analytical and finite element modeling). The aim of this paper is to present the choices made regarding the behaviour law in this context, indeed, commonly used behaviour laws such as Jonhson-Cook can bring unsatisfactory results especially for high strain and large deformation processes. This study develops a large deformation strain-gradient theoretical framework with hypothesis linked with to metal cutting processes. The emphasis of the theory is placed on the existence of high shear phenomena creating a texture in the primary shear band. To account for the texture, the plastic spin is supposed to be relevant in this theory. It is shown that the theory as the capability of interpreting the complex phenomena found in machining and more particularly in high speed machining

Souterrain-refuge et Grotte de la Ferrage. Station inédite à Varages (Var)

Corbeil R., Royer Paul, Gérard R. Souterrain-refuge et Grotte de la Ferrage. Station inédite à Varages (Var). In: Bulletin de la Société préhistorique de France, tome 41, n°4-6, 1944. pp. 91-103

Modified polystyrene for WOLED applications: materials issues

International audienc

Self-assembly of metallic nanorings for plasmonic applications

International audienc