Anisotropic self-affine properties of experimental fracture surfaces

The scaling properties of post-mortem fracture surfaces of brittle (silica glass), ductile (aluminum alloy) and quasi-brittle (mortar and wood) materials have been investigated. These surfaces, studied far from the initiation, were shown to be self-affine. However, the Hurst exponent measured along the crack direction is found to be different from the one measured along the propagation direction. More generally, a complete description of the scaling properties of these surfaces call for the use of the 2D height-height correlation function that involves three exponents zeta = 0.75, beta = 0.6 and z = 1.25 independent of the material considered as well as of the crack growth velocity. These exponents are shown to correspond to the roughness, growth and dynamic exponents respectively, as introduced in interface growth models. They are conjectured to be universal.Comment: 12 page

Détection du lanceur ExoMars launcher lors de son passage au-dessus de l'Europe avec le démonstrateur radar de Surveillance de l'Espace

International audienceA bistatic radar breadboard for space surveillance has been developed by ONERA for the European Space Agency. This item was operated during the launch of the ExoMars mission on March 14th 2016. The spacecraft, attached to the Proton launcher, was well detected in real-time during its passage over South Europe. This paper presents the setting up of an experiment to detect this particular type of targets with the radar breadboard. The results of its operation as space surveillance system as well as a specific kinematic analysis of the ExoMars spacecraft as viewed from the radar.Un démonstrateur de radar bistatique pour la surveillance spatiale a été développée par l'ONERA pour l'Agence Spatiale Européenne (ESA). Ce moyen a été mis en oeuvre lors du lancement de la mission ExoMars le 14 mars 2016. Le vaisseau spatial, attaché au lanceur Proton, a été détecté en temps réel lors de son passage au-dessus de l'Europe du Sud. Cet article présente le démonstrateur radar et les résultats de son fonctionnement en tant que système de surveillance spatiale ainsi qu'une analyse cinématique spécifique du lanceur spatial ExoMars vu depuis le radar

Effect of endurance training on different mechanical efficiency indices during submaximal cyclin in subjects unaccustomed to cycling

International audienceThe purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exercise as baseline correction), to reveal the effect of endurance training on mechanical efficiency. Nine healthy sedentary women undertook an incremental test and submaximal cycling exercise, at an intensity corresponding to 50% of the pretraining peak oxygen uptake, before and after 6 weeks of endurance training (18 sessions of 45 min). The training effects on efficiency indices were tested by comparisons based on GE, NE, and WE as well as by the differences between the percentage changes of all indices (% GE, % NE, % WE). Endurance training resulted in significantly higher GE (+ 11.1%; p < 0.001) and NE (+ 9.1%; P < 0.01). Only minor significant improvement (+ 2.4%; p < 0.05) was observed with the WE index because the value used for baseline subtraction was significantly reduced by the training sessions, due perhaps to improvement in pedaling skill. As a consequence, % WE was significantly lower than % GE (p < 0.01) and % NE (p < 0.05), while % GE and % NE were not significantly different. We conclude that mechanical efficiency of cycling increases with training in women previously unfamiliar with cycling, and that the WE index is less sensitive to this training effect than GE and NE indices. Key words: gross efficiency, net efficiency, work efficiency, internal work, cycle ergomete

Scaling properties of mortar fracture surfaces

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Effect of Endurance Training on Different Mechanical Efficiency Indices During Submaximal Cycling in Subjects Unaccustomed to Cycling

International audienceThe purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exercise as baseline correction), to reveal the effect of endurance training on mechanical efficiency. Nine healthy sedentary women undertook an incremental test and submaximal cycling exercise, at an intensity corresponding to 50% of the pretraining peak oxygen uptake, before and after 6 weeks of endurance training (18 sessions of 45 min). The training effects on efficiency indices were tested by comparisons based on GE, NE, and WE as well as by the differences between the percentage changes of all indices (% GE, % NE, % WE). Endurance training resulted in significantly higher GE (+ 11.1%; p < 0.001) and NE (+ 9.1%; P < 0.01). Only minor significant improvement (+ 2.4%; p < 0.05) was observed with the WE index because the value used for baseline subtraction was significantly reduced by the training sessions, due perhaps to improvement in pedaling skill. As a consequence, % WE was significantly lower than % GE (p < 0.01) and % NE (p < 0.05), while % GE and % NE were not significantly different. We conclude that mechanical efficiency of cycling increases with training in women previously unfamiliar with cycling, and that the WE index is less sensitive to this training effect than GE and NE indices. Key words: gross efficiency, net efficiency, work efficiency, internal work, cycle ergomete

Nonlinear behavior of CRF device at high power level

International audienceThis paper investigates the nonlinear behavior of CRF filters. First, measurements carried out on stand-alone resonators underline the impact of resonator size and loading layer thickness on linearity. Then, a comparison between a BAW filter and a CRF filter is presented regarding second order nonlinearities. Finally, the nonlinear behavior of CRF filters at high power levels has been investigated through co-integration of the CRF with a silicon PA in order to evaluate its impact in a WCDMA application

Band reject filter in BAW technology.

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Overall increase in heart rate variability after the Square-Wave Endurance Exercise Test training

Effets d'un entraînement en endurance de type SWEET(exercice sur ergocycle en créneaux de 45 minutes, 3 fois par semaine) pendant 6 semaines sur la variabilité de la fréquence cardiaque lors du repos couché, de l'orthostatisme à 60° et d'un exercice sous-maximal chez 14 jeunes femmes en bonne santé. Objectif d'amélioration de l'état fonctionnel du système nerveux végétatif, dans un but thérapeutique chez des patients souffrant de pathologies cardiovasculaires et préventif chez des sujets asymptomatiques