Post-processing the strain waves in split Hopkinson pressure bars to get the stress-strain in the sample requires the knowledge of the characteristic wave speed c0 in the measuring bars. In the context of metrology, the measurement uncertainty in the value of c0 must be assessed. The aim is to minimize this uncertainty, which depends on the way c0 ...
Published in Space Science Reviews
By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars’ surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six se...
Cn² est la constante de structure de l'indice de réfraction provoquée par les variations de température, d'humidité et de pression dans l'atmosphère. Le profil de Cn² caractérise localement la force de la turbulence. La méthode CO-SLIDAR, développée par l’ONERA, permet de réaliser des profils de Cn² le long de la ligne de visée d'un télescope à par...
Les travaux présentés portent sur la recherche, l'analyse et la mise en oeuvre de méthodes numériques pour la simulation des phénomènes de propagation et de diffraction d'ondes acoustiques, électromagnétiques et élastiques.La première partie s'intéresse à la recherche de méthodes performantes pour la simulation des phénomènes de propagation d'ondes...
Published in The Journal of the Acoustical Society of America
Knowledge of acoustic properties is crucial for ultrasonic or sonic imaging and signal detection in nondestructive evaluation (NDE), medical imaging, and seismology. Accurately and reliably obtaining these is particularly challenging for the NDE of high-density polyethylene (HDPE), such as is used in many water or gas pipes, because the properties ...
In order to detect possible signal redundancies in the ambient seismic wavefield, we develop a new method based on pairwise comparisons among a set of synchronous time-series. This approach is based on instantaneous phase coherence statistics. The first and second moments of the pairwise phase coherence distribution are used to characterize the pha...
The Finite-Difference Time-Domain (FDTD) method in cylindrical coordinates is used to describe electromagnetic wave propagation in a cold magnetized plasma. This enables us to study curvature effects in toroidal plasma. We derive the discrete dispersion relation of this FDTD scheme and compare it with the exact solution. The accuracy analysis of th...
