Precision Position Control of the DelFly II Flapping-wing Micro Air Vehicle in a Wind-tunnel

Flapping-wing MAVs represent an attractive alternative to conventional designs with rotary wings, since they promise a much higher efficiency in forward flight. However, further insight into the flapping-wing aerodynamics is still needed to get closer to the flight performance observed in natural fliers. Here we present the first step necessary to perform a flow visualization study of the air around the flapping wings of a DelFly II MAV in-flight: a precision position control of flight in a wind-tunnel. We propose a hierarchical control scheme implemented in the open-source Paparazzi UAV autopilot software. Using a decoupling, combined feed-forward and feed-back control approach as a core, we were able to achieve a precision of 2:5 cm for several seconds, which is much beyond the requirements for a time resolved stereo PIV technique.Control & Simulatio

Determination of Micrometer Length Scales with an X-ray Reflection Ultra Small-Angle Scattering Set-Up

We show that the accessible range of length scales of structures deduced with ultra small-angle scattering (USAX) experiments can be enlarged by more than one order of magnitude in reflection geometry set-ups. From the analysis of the diffuse scattering without further model assumptions the length scale of the structures is determinable. The method is illustrated by an example of thin blend films of deuterated polystyrene (dPS) and polyparamethylstyrene (PpMS) where μm-structures are recovered. The results are compared to atomic-force microscopy measurements. For a further comparison, USAX data of a water-based dispersion of polymer particles are presented. They illustrate the resolvable length scale of the conventional transmission geometry

Determination of micrometer length scales with an X-ray reflection ultra small-angle scattering set-up

We show that the accessible range of length scales of structures deduced with ultra small-angle scattering (USAX) experiments can be enlarged by more than one order of magnitude in reflection geometry set-ups. From the analysis of the diffuse scattering without further model assumptions the length scale of the structures is determinable. The method is illustrated by an example of thin blend films of deuterated polystyrene (dPS) and polyparamethylstyrene (PpMS) where μm-structures are recovered. The results are compared to atomic-force microscopy measurements. For a further comparison, USAX data of a water-based dispersion of polymer particles are presented. They illustrate the resolvable length scale of the conventional transmission geometry

Étude de la fonction de la protéine OPA1, dynamine mitochondriale, dans les cellules ganglionnaires de la rétine (implication dans les atrophies optiques héréditaires)

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Investigation of failure mechanisms in polymer composites by simultaneous measurement of ultra-small-angle scattering and acoustic emission during the deformation. I. Method

Failure mechanisms in polymer composites were investigated with the method of ultra-small-angle X-ray scattering using synchrotron radiation and acoustic emission analysis simultaneously. The composites were prepared from polystyrene filled with glass beads with different coatings. The two-dimensional scattering patterns were analyzed by means of a cylinder model, while the curves of the acoustic emission signals per stress or amplitude interval were calculated and fitted by a Weibull distribution function

Investigation of failure mechanisms in polymer composites by simultaneous measurement of ultra-small-angle scattering and acoustic emission during the deformation. II. Evaluation of the interface strength

The failure mechanism in polystyrene (PS) filled with glass beads was investigated with the methods of ultra-small-angle X-ray scattering (USAXS) and acoustic emission (AE) analysis simultaneously. The interface in the composites was tailored using carboxyl-terminated PS (PS-COOH). Monolayers of PSCOOH were prepared on the glass surface in a wide range of grafting densities, from single chains to a polymer brush. The layers were characterized by ellipsometry, scanning probe microscopy, and the wetting method. The morphology of the layers is in good agreement with the theoretical predictions. USAXS experiments identify submicrovoids (SMVs) at the interface in the composites even before a tensile deformation. The uniaxial loading of the specimens is followed by a debonding (dewetting) process that is identified by simultaneous increase of integral scattering intensity and AE signals. The stress of debonding is proportional to the grafting density of PS-COOH. The amplitude of the A