A5073526940- Granular flow and fluidized beds
- Seismic Waves and Analysis
- Ultrasonics and Acoustic Wave Propagation
- Landslides and related hazards
- Material Dynamics and Properties
- Geophysical Methods and Applications
- Seismic Imaging and Inversion Techniques
- Geotechnical and Geomechanical Engineering
- Acoustic Wave Resonator Technologies
- Adhesion, Friction, and Surface Interactions
- earthquake and tectonic studies
- Environmental Toxicology and Ecotoxicology
- Microwave Imaging and Scattering Analysis
- Thermography and Photoacoustic Techniques
- Drilling and Well Engineering
- Mercury impact and mitigation studies
- Rock Mechanics and Modeling
- Mechanical and Optical Resonators
- Optical and Acousto-Optic Technologies
- Marine Bivalve and Aquaculture Studies
- Effects and risks of endocrine disrupting chemicals
- Advanced Fiber Optic Sensors
- Marine and fisheries research
- Water Quality Monitoring Technologies
- Heavy metals in environment
Centre National de la Recherche Scientifique
2016-2025
Institut Langevin
2015-2025
ESPCI Paris
2016-2025
Institut Jean Nicod
2014-2025
Université Paris Sciences et Lettres
2017-2024
Southwest Jiaotong University
2024
CRRC (China)
2021-2024
ParisTech
2013-2023
Ministry of Education
2023
Zhengzhou University
2023
Experimental observations of pulsed ultrasonic transmission through granular glass beads under oedometric loading are presented. We observe in the transmitted signals coexistence a coherent ballistic pulse traveling an ``effective contact medium'' and specklelike multiply scattered signal. The relative amplitudes these strongly depend on ratios bead size to wavelength detector size. data support recent descriptions inhomogeneous stress field within media.
Abstract To obtain critical information on distribution and abundance of Indo-Pacific humpback dolphins ( Sousa chinensis ) residing in the Pearl River Estuary (PRE), systematic line-transect surveys photo-identification studies were conducted eastern western sections estuary 2005–2006 2007–2008, respectively. Dolphins section occurred throughout Lingding Bay, whereas their extended from mouth Modaomen to channel between Shangchuan Xiachuan islands. Variations dolphin during wet dry seasons...
Sound velocity measurements in dense glass bead packs reveal significant softening effect at large amplitudes, due to the frictional nonlinearity grain contacts. Beyond a certain amplitude, sound-matter interaction becomes irreversible, leaving medium weakened and slightly compacted state. A slow recovery of initial elastic modulus is observed after acoustic perturbation, revealing plastic creep growth microcontacts. The cross-correlation function configuration-specific speckles highlights...
We study the multiple scattering of short-wavelength ultrasound through force networks in dry and wet glass bead packings under stress. Over long distance scales, diffusion approximation is shown to describe adequately transport elastic waves dominated by shear waves. The recovered mean path reveals a short-range correlation chains. Also we observe drastic effect wetting liquids on energy dissipation granular medium. relevance these experimental findings for seismological applications discussed.
The dissipation of an elastic wave in dry and wet glass bead packings is measured using multiple sound scattering. interplay a linear viscoelastic loss nonlinear frictional one observed media. Mindlin model provides qualitative description the experiment, but fails to quantitatively account for data due grain roughness. In weakly media, we find that dominated by viscous liquid films trapped at surface asperities. Adding more enables us form capillary menisci does not increase energy loss.
Understanding the mechanisms behind remote triggering of landslides by seismic waves at micro-strain amplitude is essential for quantifying hazards. Granular materials provide a relevant model system to investigate within unjamming transition framework, from solid liquid states. Furthermore, recent laboratory experiments have revealed that ultrasound-induced granular avalanches can be related reduction in interparticle friction through shear acoustic lubrication contacts. However,...
As waves propagate through a complex medium, they undergo multiple scattering events. This phenomenon is detrimental to imaging, as it causes full blurring of the image beyond transport mean free path. Here, we show how detect, localize, and characterize any target reflection matrix medium in which this embedded thus hidden from direct view. More precisely, introduce fingerprint operator that contains specific signature with respect its environment. Applied recorded matrix, provides...
Laboratory studies of granular friction have emerged as a powerful tool for investigating seismic fault slip [1], including dynamic triggering earthquakes and landslides [2,3]. However, physical origins by small strain amplitude from large remote earthquake still remain unclear.Here we report the experimental investigation quasi-static sliding in dry wet gouges layers under constant pressure, monitored with passive (acoustic emission: AE) active acoustic detections (wave velocity coda...
Understanding the dynamic response of granular shear zones under cyclic loading is critical for elucidating mechanisms earthquake-induced landslides. Existing prediction methods struggle to capture complexities landslide dynamics, particularly transition from slow creep rapid runout during seismic events. Here, we present results ring experiments that simulate zone behavior loading. Our study reveals exhibit post-seismic creep, which increases gradually with each cycle. Crucially, have...
We have analyzed the impact of different forcings, such as rain and seismicity, on slope instabilites an active volcano. For this, we compiled a catalog locations volumes rockfalls in Piton de la Fournaise crater using seismic records. validated it by comparing to those deduced from photogrammetric data. 10,477 rockfalls, spanning period 2014 2016. This corresponds renewal volcanic activity after 41‐month rest. Our analysis reveals that renewed eruptive has unsettled edges. External forcings...
Stress-strain measurements and ultrasound propagation experiments in glass bead packs have been simultaneously conducted to characterize the stress-induced anisotropy under uniaxial loading. These realized, respectively, with finite incremental deformations of granular assembly, are analyzed within framework effective-medium theory based on Hertz-Mindlin contact theory. Our work shows that both compressional shear wave velocities consequently elastic moduli agree fairly well an model...
Nonlinear sound propagation in a stressed glass bead pack is investigated via amplitude measurements of harmonic generation. We evidence two distinct regimes sound‐matter interaction: reversible and irreversible, as function the ratio r s between dynamic strain static one. In regime, higher harmonics generated agree well with mean‐field model based on Hertz contact theory, coefficient nonlinearity β deduced from measured second‐harmonic consistent that acoustoelastic measurement. Beyond...
Wedge (or line) acoustic waves, propagating along the tip of an elastic wedge waveguide, are generated by pulsed YAG laser impact and detected a wideband optical interferometer. In ideal infinitely sharp tall guide, antisymmetrical flexural (ASF) modes nondispersive their energies mostly confined near tip. The displacement measurements with probe on metallic wedges show broadband wave forms ASF modes. Dispersive behavior these forms, which not predicted theoretical models, clearly...
We investigate the mechanical responses of dense granular materials, using a direct shear box combined with simultaneous acoustic measurements. Measured wave speeds evidence structural change material under shear, from jammed state to flowing state. There is clear signature when band formed. Subjected cyclic both stress and speed show strong hysteretic dependence on strain, likely associated geometry in packing structure. Moreover, correlation function configuration-specific multiply...
We investigate the elastic behavior and damage of weakly cemented granular media under external load with ultrasound. The cementation controlled experiments are performed by freezing capillary liquid at bead contact in a dense glass or polymeric [poly(methyl methacrylate)] pack wet tetradecane volume fraction \ensuremath{\phi} = 0.1%--4%. When pendular rings solidified, an abrupt increase factor 2 compressional wave velocity is observed. interpret data terms effective medium models which...
Abstract Phenanthrene is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) found in continental shelf environment China and on EPA’s Priority Pollutant list. In this study, effects phenanthrene marine algal growth rate were determined after 96-h exposure at pH 6.0, 7.0, 8.0, 9.0, 10.0 seawater salinity 35. Two measuring techniques to assess inhibition also compared using prompt fluorescence microscopic cell count. The results showed that toxicity increased significantly ( p...
A modal analysis is presented to describe the excitation of Lamb waves in an elastic plate using a liquid wedge transducer. Analytical expression for displacement given mode derived by uniform bounded beam. In contrast previous studies, contribution reflected wave included input exciting forces perturbation theory. The conversion efficiency, defined as ratio guided power incident power, related single parameter which depends on rate attenuation due leakage from into wedge. Numerical results...
Surface acoustic waves (SAW’s) have been optically generated and detected on metallic spheres. The source was a focused yttrium aluminum garnet (YAG) laser operated in the Q-switched mode probe sensitive optical heterodyne interferometer. curvature of surface gives rise to dispersive effects. variation SAW group velocity is deduced from evolving waveforms pulses after propagating few turns around sphere. observation pulse at positions away pole (a point diametrically opposite source) reveals...