The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform

Philippe Lasaygues - One of the best experts on this subject based on the ideXlab platform.

  • Measuring mass Density and ultrasonic wave velocity: A wavelet-based method applied in ultrasonic reflection mode
    Ultrasonics, 2016
    Co-Authors: Khaled Metwally, Emmanuelle Lefevre, Cécile Baron, Rui Zheng, Martine Pithioux, Philippe Lasaygues
    Abstract:

    When assessing ultrasonic measurements of Material parameters, the signal processing is an important part of the inverse problem. Measurements of thickness, ultrasonic wave velocity and mass Density are required for such assessments. This study investigates the feasibility and the robustness of a wavelet-based processing (WBP) method based on a Jaffard–Meyer algorithm for calculating these parameters simultaneously and independently, using one single ultrasonic signal in the reflection mode. The appropriate transmitted incident wave, correlated with the mathematical properties of the wavelet decomposition, was determined using a adapted identification procedure to build a mathematically equivalent model for the electro-acoustic system. The method was tested on three groups of samples (polyurethane resin, bone and wood) using one 1-MHz transducer. For thickness and velocity measurements, the WBP method gave a relative error lower than 1.5%. The relative errors in the mass Density measurements ranged between 0.70% and 2.59%. Despite discrepancies between manufactured and biological samples, the results obtained on the three groups of samples using the WBP method in the reflection mode were remarkably consistent, indicating that it is a reliable and efficient means of simultaneously assessing the thickness and the velocity of the ultrasonic wave propagating in the medium, and the apparent mass Density of Material.

Khaled Metwally - One of the best experts on this subject based on the ideXlab platform.

  • Measuring mass Density and ultrasonic wave velocity: A wavelet-based method applied in ultrasonic reflection mode
    Ultrasonics, 2016
    Co-Authors: Khaled Metwally, Emmanuelle Lefevre, Cécile Baron, Rui Zheng, Martine Pithioux, Philippe Lasaygues
    Abstract:

    When assessing ultrasonic measurements of Material parameters, the signal processing is an important part of the inverse problem. Measurements of thickness, ultrasonic wave velocity and mass Density are required for such assessments. This study investigates the feasibility and the robustness of a wavelet-based processing (WBP) method based on a Jaffard–Meyer algorithm for calculating these parameters simultaneously and independently, using one single ultrasonic signal in the reflection mode. The appropriate transmitted incident wave, correlated with the mathematical properties of the wavelet decomposition, was determined using a adapted identification procedure to build a mathematically equivalent model for the electro-acoustic system. The method was tested on three groups of samples (polyurethane resin, bone and wood) using one 1-MHz transducer. For thickness and velocity measurements, the WBP method gave a relative error lower than 1.5%. The relative errors in the mass Density measurements ranged between 0.70% and 2.59%. Despite discrepancies between manufactured and biological samples, the results obtained on the three groups of samples using the WBP method in the reflection mode were remarkably consistent, indicating that it is a reliable and efficient means of simultaneously assessing the thickness and the velocity of the ultrasonic wave propagating in the medium, and the apparent mass Density of Material.

Jacques Dubochet - One of the best experts on this subject based on the ideXlab platform.

  • the mammalian central nervous synaptic cleft contains a high Density of periodically organized complexes
    Proceedings of the National Academy of Sciences of the United States of America, 2005
    Co-Authors: Benoit Zuber, Irina Nikonenko, Paul Klauser, Dominique Muller, Jacques Dubochet
    Abstract:

    Cryo-electron microscopy of vitreous section makes it possible to observe cells and tissues at high resolution in a close-to-native state. The specimen remains hydrated; chemical fixation and staining are fully avoided. There is minimal molecular aggregation and the Density observed in the image corresponds to the Density in the object. Accordingly, organotypic hippocampal rat slices were vitrified under high pressure and controlled cryoprotection conditions, cryosectioned at a final thickness of approximately 70 nm and observed below -170 degrees C in a transmission electron microscope. The general aspect of the tissue compares with previous electron microscopy observations. The detailed analysis of the synapse reveals that the Density of Material in the synaptic cleft is high, even higher than in the cytoplasm, and that it is organized in 8.2-nm periodic transcleft complexes. Previously undescribed structures of presynaptic and postsynaptic elements are also described.

Cécile Baron - One of the best experts on this subject based on the ideXlab platform.

  • Measuring mass Density and ultrasonic wave velocity: A wavelet-based method applied in ultrasonic reflection mode
    Ultrasonics, 2016
    Co-Authors: Khaled Metwally, Emmanuelle Lefevre, Cécile Baron, Rui Zheng, Martine Pithioux, Philippe Lasaygues
    Abstract:

    When assessing ultrasonic measurements of Material parameters, the signal processing is an important part of the inverse problem. Measurements of thickness, ultrasonic wave velocity and mass Density are required for such assessments. This study investigates the feasibility and the robustness of a wavelet-based processing (WBP) method based on a Jaffard–Meyer algorithm for calculating these parameters simultaneously and independently, using one single ultrasonic signal in the reflection mode. The appropriate transmitted incident wave, correlated with the mathematical properties of the wavelet decomposition, was determined using a adapted identification procedure to build a mathematically equivalent model for the electro-acoustic system. The method was tested on three groups of samples (polyurethane resin, bone and wood) using one 1-MHz transducer. For thickness and velocity measurements, the WBP method gave a relative error lower than 1.5%. The relative errors in the mass Density measurements ranged between 0.70% and 2.59%. Despite discrepancies between manufactured and biological samples, the results obtained on the three groups of samples using the WBP method in the reflection mode were remarkably consistent, indicating that it is a reliable and efficient means of simultaneously assessing the thickness and the velocity of the ultrasonic wave propagating in the medium, and the apparent mass Density of Material.

Rui Zheng - One of the best experts on this subject based on the ideXlab platform.

  • Measuring mass Density and ultrasonic wave velocity: A wavelet-based method applied in ultrasonic reflection mode
    Ultrasonics, 2016
    Co-Authors: Khaled Metwally, Emmanuelle Lefevre, Cécile Baron, Rui Zheng, Martine Pithioux, Philippe Lasaygues
    Abstract:

    When assessing ultrasonic measurements of Material parameters, the signal processing is an important part of the inverse problem. Measurements of thickness, ultrasonic wave velocity and mass Density are required for such assessments. This study investigates the feasibility and the robustness of a wavelet-based processing (WBP) method based on a Jaffard–Meyer algorithm for calculating these parameters simultaneously and independently, using one single ultrasonic signal in the reflection mode. The appropriate transmitted incident wave, correlated with the mathematical properties of the wavelet decomposition, was determined using a adapted identification procedure to build a mathematically equivalent model for the electro-acoustic system. The method was tested on three groups of samples (polyurethane resin, bone and wood) using one 1-MHz transducer. For thickness and velocity measurements, the WBP method gave a relative error lower than 1.5%. The relative errors in the mass Density measurements ranged between 0.70% and 2.59%. Despite discrepancies between manufactured and biological samples, the results obtained on the three groups of samples using the WBP method in the reflection mode were remarkably consistent, indicating that it is a reliable and efficient means of simultaneously assessing the thickness and the velocity of the ultrasonic wave propagating in the medium, and the apparent mass Density of Material.