Pierre-Yves Le Bas - Profile on Academia.edu (original) (raw)

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Papers by Pierre-Yves Le Bas

Research paper thumbnail of Effects of Acoustic Waves on Stick---Slip Behavior in Sheared Granular Media With Implications to Dynamic Earthquake Triggering and Slow Slip

Research paper thumbnail of System and method to create three-dimensional images of non-linear acoustic properties in a region remote from a borehole

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), 2013

Research paper thumbnail of System and method to estimate compressional to shear velocity (VP/VS) ratio in a region remote from a borehole

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Oct 16, 2012

Research paper thumbnail of Direct observation of copper precipitation in a neutron irradiated FeCu alloy by 3D atomic tomography

Scripta Metallurgica Et Materialia, Oct 1, 1995

Research paper thumbnail of System and method for generating micro-seismic events and characterizing properties of a medium with non-linear acoustic interactions

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 29, 2015

Research paper thumbnail of System and method for investigating sub-surface features and 3D imaging of non-linear property, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 2, 2015

Research paper thumbnail of System and method for investigating sub-surface features of a rock formation using compressional acoustic sources

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Sep 27, 2016

Research paper thumbnail of High Amplitude Non Contact Acoustic Source for Defect Detection and 3-component Excitation

Research paper thumbnail of Parametric interactions of waves in rocks

Parametric interactions of waves in rocks

Research paper thumbnail of Detonation command and control

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 5, 2017

Research paper thumbnail of Data acquisition and processing system and method for investigating sub-surface features of a rock formation

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jan 27, 2015

Research paper thumbnail of System and method for investigating sub-surface features of a rock formation with acoustic sources generating coded signals

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 30, 2014

Research paper thumbnail of Reflection and transmission by randomly spaced elastic cylinders in a fluid slab-like region

Journal of the Acoustical Society of America, Mar 1, 2005

V. Twersky developed in the sixties a theory describing the reflection and transmission process o... more V. Twersky developed in the sixties a theory describing the reflection and transmission process of scalar plane waves from slab-like regions of randomly distributed scatterers. The theory, which is based on Foldy's approximation and neglects "hole corrections", is an alternative approach to an exact calculation of multiple scattering that fails when the number of scatterers is important. Twerky's theory furnishes the properties of the coherent plane wave propagating inside the slab. From the point of view of the coherent wave, the slab may be described as an effective fluid medium; its reflection and transmission coefficients may be formally written as those of a fluid plate. In this work, Twersky's theory is extended to random distributions of cylindrical inclusions in elastic media. Before examining the reflection and transmission process of such multiple scattering media, our first objective is to theoretically validate the results predicted by the theory. With this aim in view, as an exact calculation of multiple scattering fails for purely random distributions, the idea consists in adapting Twersky's theory to distributions of scatterers periodic in one direction and random in the other one. Indeed, the reflection and transmission coefficients of such half-periodic media can be calculated by using a method originally developed for purely periodic media, i.e. phononic crystals. In our case, it consists in considering each half-periodic medium as a random distribution of linear periodic arrays of scatterers. This method furnishes exact reflection and transmission coefficients which can be successfully compared with those predicted by Twersky's theory.

Research paper thumbnail of Diffusion multiple par des cibles élastiques immergées : propagation d'ondes cohérentes et interactions résonantes

Research paper thumbnail of Flaw detection of wellbore systems by combining time reversal methods and nonlinear acoustic measurements

Flaw detection of wellbore systems by combining time reversal methods and nonlinear acoustic measurements

The Journal of the Acoustical Society of America

A wellbore system consisting of a steel pipe cased in cement is susceptible to cracking and delam... more A wellbore system consisting of a steel pipe cased in cement is susceptible to cracking and delamination. Such flaws greatly reduce the integrity of the wellbore and can lead to significant leakage. To resolve the location and extent of the defects, we have combined a unique time reversal method with nonlinear acoustic evaluation. The time reversal method generates a compact high-amplitude wave only in a localized area that can be used to probe the acoustic properties spot by spot of a three dimensional region. Additionally, the nonlinear acoustic signal an object exhibits is far more sensitive to damage and defects than conventional linear analysis. The nonlinear behavior can be locally determined by observing the changes in elastic properties as the amplitude of the time-reversed focus wave is increased. The experimental setup consist of an array of piezoelectric transducers for generating the focused energy and a laser vibrometer mounted on a scanning frame for focusing and measu...

Research paper thumbnail of Nonlinear acoustics evaluation of CO2 exposed sandstone

Nonlinear acoustics evaluation of CO2 exposed sandstone

The Journal of the Acoustical Society of America

In an effort to better understand the hygro-thermo-mechanical behavior of geologic CO2 reservoir ... more In an effort to better understand the hygro-thermo-mechanical behavior of geologic CO2 reservoir material, we investigate the non-linear behavior of elastic wave propagation in Berea sandstone samples, which are used as a standard for reservoir rock formations. Nonlinear characterization methods, including resonant ultrasound spectroscopy (RUS), dynamic acousto-elasticity (DAET), and single-impact nonlinear resonance techniques, are applied to pristine, damaged (distributed microfractures), and CO2 injected Berea samples; conventional linear vibrational and wave propagation measurements are also applied to the samples. The results of these sensitive test methods are compared to reveal the characteristics of geologic reservoir materials that are most affected by varying microstructural and environmental conditions. An analysis of the work also leads to potential bases for test methods that could be deployed in the field in the future to monitor the condition of reservoir formations a...

Research paper thumbnail of Diffusion multiple par des cibles élastiques immergées. Propagation d'ondes cohérentes et interactions résonantes

diffuseurs elastiques aleatoirement repartis. Cette etude se compose de trois parties. La premier... more diffuseurs elastiques aleatoirement repartis. Cette etude se compose de trois parties. La premiere partie s'interesse a un nombre restreint de diffuseurs. Elle a permis de mettre en evidence un phenomene de couplage resonant entre des diffuseurs cylindriques proches se manifestant par une demultiplication des frequences de resonances associees a l'onde A (onde de Scholte-Stoneley). Ces demultiplications ont ete validees experimentalement. La seconde partie presente deux theories de milieu effectif : celle de Waterman et Truell et celle de Fikioris et Waterman. La philosophie de ces deux theories est de determiner l'onde moyenne resultant d'un moyennage sur les positions des diffuseurs. C'est cette onde que l'on appelle onde coherente. Ces theories aboutissent au calcul d'un nombre d'onde effectif caracterisant l'onde coherente. La difference essentielle entre ces deux theories reside dans la prise en compte de la taille des diffuseurs dans celle d...

Research paper thumbnail of Non-Linear Acoustics for Non-Destructive testing

Research paper thumbnail of Reflection and transmission by randomly spaced elastic cylinders in a fluid slab-like region

The Journal of the Acoustical Society of America, 2005

An extension of Fikioris and Waterman’s formalism is developed in order to describe both the refl... more An extension of Fikioris and Waterman’s formalism is developed in order to describe both the reflection and transmission from a slab-like fluid region in which elastic cylindrical scatterers are randomly placed. The dispersion equation of the coherent wave inside the slab must be solved numerically. For solid cylinders, there is only one solution corresponding to a mean free path of the coherent wave larger than one wavelength. In that case, the slab region may be described as an effective dissipative fluid medium, and its reflection and transmission coefficients may be formally written as those of a fluid plate. For thin hollow shells, a second solution of the dispersion equation is found, at concentrations large enough for the shells to be coupled via the radiation of a circumferential Scholte–Stoneley A wave on each shell. This occurs at a few resonance frequencies of the shells. At those frequencies, then, two different coherent waves propagate in the slab, and it can no longer ...

Research paper thumbnail of Nonlinear Acoustic Methods for the Detection and Monitoring of CO2/Brine Leakage Pathways in Wellbore Systems

Research paper thumbnail of Effects of Acoustic Waves on Stick---Slip Behavior in Sheared Granular Media With Implications to Dynamic Earthquake Triggering and Slow Slip

Research paper thumbnail of System and method to create three-dimensional images of non-linear acoustic properties in a region remote from a borehole

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), 2013

Research paper thumbnail of System and method to estimate compressional to shear velocity (VP/VS) ratio in a region remote from a borehole

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Oct 16, 2012

Research paper thumbnail of Direct observation of copper precipitation in a neutron irradiated FeCu alloy by 3D atomic tomography

Scripta Metallurgica Et Materialia, Oct 1, 1995

Research paper thumbnail of System and method for generating micro-seismic events and characterizing properties of a medium with non-linear acoustic interactions

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 29, 2015

Research paper thumbnail of System and method for investigating sub-surface features and 3D imaging of non-linear property, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 2, 2015

Research paper thumbnail of System and method for investigating sub-surface features of a rock formation using compressional acoustic sources

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Sep 27, 2016

Research paper thumbnail of High Amplitude Non Contact Acoustic Source for Defect Detection and 3-component Excitation

Research paper thumbnail of Parametric interactions of waves in rocks

Parametric interactions of waves in rocks

Research paper thumbnail of Detonation command and control

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 5, 2017

Research paper thumbnail of Data acquisition and processing system and method for investigating sub-surface features of a rock formation

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jan 27, 2015

Research paper thumbnail of System and method for investigating sub-surface features of a rock formation with acoustic sources generating coded signals

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Dec 30, 2014

Research paper thumbnail of Reflection and transmission by randomly spaced elastic cylinders in a fluid slab-like region

Journal of the Acoustical Society of America, Mar 1, 2005

V. Twersky developed in the sixties a theory describing the reflection and transmission process o... more V. Twersky developed in the sixties a theory describing the reflection and transmission process of scalar plane waves from slab-like regions of randomly distributed scatterers. The theory, which is based on Foldy's approximation and neglects "hole corrections", is an alternative approach to an exact calculation of multiple scattering that fails when the number of scatterers is important. Twerky's theory furnishes the properties of the coherent plane wave propagating inside the slab. From the point of view of the coherent wave, the slab may be described as an effective fluid medium; its reflection and transmission coefficients may be formally written as those of a fluid plate. In this work, Twersky's theory is extended to random distributions of cylindrical inclusions in elastic media. Before examining the reflection and transmission process of such multiple scattering media, our first objective is to theoretically validate the results predicted by the theory. With this aim in view, as an exact calculation of multiple scattering fails for purely random distributions, the idea consists in adapting Twersky's theory to distributions of scatterers periodic in one direction and random in the other one. Indeed, the reflection and transmission coefficients of such half-periodic media can be calculated by using a method originally developed for purely periodic media, i.e. phononic crystals. In our case, it consists in considering each half-periodic medium as a random distribution of linear periodic arrays of scatterers. This method furnishes exact reflection and transmission coefficients which can be successfully compared with those predicted by Twersky's theory.

Research paper thumbnail of Diffusion multiple par des cibles élastiques immergées : propagation d'ondes cohérentes et interactions résonantes

Research paper thumbnail of Flaw detection of wellbore systems by combining time reversal methods and nonlinear acoustic measurements

Flaw detection of wellbore systems by combining time reversal methods and nonlinear acoustic measurements

The Journal of the Acoustical Society of America

A wellbore system consisting of a steel pipe cased in cement is susceptible to cracking and delam... more A wellbore system consisting of a steel pipe cased in cement is susceptible to cracking and delamination. Such flaws greatly reduce the integrity of the wellbore and can lead to significant leakage. To resolve the location and extent of the defects, we have combined a unique time reversal method with nonlinear acoustic evaluation. The time reversal method generates a compact high-amplitude wave only in a localized area that can be used to probe the acoustic properties spot by spot of a three dimensional region. Additionally, the nonlinear acoustic signal an object exhibits is far more sensitive to damage and defects than conventional linear analysis. The nonlinear behavior can be locally determined by observing the changes in elastic properties as the amplitude of the time-reversed focus wave is increased. The experimental setup consist of an array of piezoelectric transducers for generating the focused energy and a laser vibrometer mounted on a scanning frame for focusing and measu...

Research paper thumbnail of Nonlinear acoustics evaluation of CO2 exposed sandstone

Nonlinear acoustics evaluation of CO2 exposed sandstone

The Journal of the Acoustical Society of America

In an effort to better understand the hygro-thermo-mechanical behavior of geologic CO2 reservoir ... more In an effort to better understand the hygro-thermo-mechanical behavior of geologic CO2 reservoir material, we investigate the non-linear behavior of elastic wave propagation in Berea sandstone samples, which are used as a standard for reservoir rock formations. Nonlinear characterization methods, including resonant ultrasound spectroscopy (RUS), dynamic acousto-elasticity (DAET), and single-impact nonlinear resonance techniques, are applied to pristine, damaged (distributed microfractures), and CO2 injected Berea samples; conventional linear vibrational and wave propagation measurements are also applied to the samples. The results of these sensitive test methods are compared to reveal the characteristics of geologic reservoir materials that are most affected by varying microstructural and environmental conditions. An analysis of the work also leads to potential bases for test methods that could be deployed in the field in the future to monitor the condition of reservoir formations a...

Research paper thumbnail of Diffusion multiple par des cibles élastiques immergées. Propagation d'ondes cohérentes et interactions résonantes

diffuseurs elastiques aleatoirement repartis. Cette etude se compose de trois parties. La premier... more diffuseurs elastiques aleatoirement repartis. Cette etude se compose de trois parties. La premiere partie s'interesse a un nombre restreint de diffuseurs. Elle a permis de mettre en evidence un phenomene de couplage resonant entre des diffuseurs cylindriques proches se manifestant par une demultiplication des frequences de resonances associees a l'onde A (onde de Scholte-Stoneley). Ces demultiplications ont ete validees experimentalement. La seconde partie presente deux theories de milieu effectif : celle de Waterman et Truell et celle de Fikioris et Waterman. La philosophie de ces deux theories est de determiner l'onde moyenne resultant d'un moyennage sur les positions des diffuseurs. C'est cette onde que l'on appelle onde coherente. Ces theories aboutissent au calcul d'un nombre d'onde effectif caracterisant l'onde coherente. La difference essentielle entre ces deux theories reside dans la prise en compte de la taille des diffuseurs dans celle d...

Research paper thumbnail of Non-Linear Acoustics for Non-Destructive testing

Research paper thumbnail of Reflection and transmission by randomly spaced elastic cylinders in a fluid slab-like region

The Journal of the Acoustical Society of America, 2005

An extension of Fikioris and Waterman’s formalism is developed in order to describe both the refl... more An extension of Fikioris and Waterman’s formalism is developed in order to describe both the reflection and transmission from a slab-like fluid region in which elastic cylindrical scatterers are randomly placed. The dispersion equation of the coherent wave inside the slab must be solved numerically. For solid cylinders, there is only one solution corresponding to a mean free path of the coherent wave larger than one wavelength. In that case, the slab region may be described as an effective dissipative fluid medium, and its reflection and transmission coefficients may be formally written as those of a fluid plate. For thin hollow shells, a second solution of the dispersion equation is found, at concentrations large enough for the shells to be coupled via the radiation of a circumferential Scholte–Stoneley A wave on each shell. This occurs at a few resonance frequencies of the shells. At those frequencies, then, two different coherent waves propagate in the slab, and it can no longer ...

Research paper thumbnail of Nonlinear Acoustic Methods for the Detection and Monitoring of CO2/Brine Leakage Pathways in Wellbore Systems

Research paper thumbnail of Ultrasonic radiation from wedges of cubic profile: Experimental results

Ultrasonic radiation from wedges of cubic profile: Experimental results

This paper presents experimental results demonstrating the increase in ultrasonic radiation obtai... more This paper presents experimental results demonstrating the increase in ultrasonic radiation obtained from a wedge of cubic profile relative to a plate of uniform thickness. The wedge of cubic profile provides high efficiency sound radiation matching layer from a mounted piezoelectric transducer into the surrounding air. Previous research on structures with indentations of power-law profile has focused on vibration mitigation using the so called "acoustic black-hole" effect, whereas here such structures are used to enhance ultrasonic radiation. The work provides experimental verification of the numerical results of Remillieux et al. (2014).