The Experts below are selected from a list of 25878 Experts worldwide ranked by ideXlab platform
Kazuto Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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Three-dimensional Acoustic Impedance mapping of cultured biological cells.
Ultrasonics, 2019Co-Authors: Naohiro Hozumi, Sachiko Yoshida, Kazuto KobayashiAbstract:Abstract The Acoustic microscope is a powerful tool for the observation of biological matters. Non-invasive in-situ observation can be performed without any staining process. Acoustic microscopy is contrasted by elastic parameters like sound speed and Acoustic Impedance. We have proposed an Acoustic microscope that can acquire three-dimensional Acoustic Impedance profile. The technique was applied to cell-size observation. Glial cells were cultured on a 70 μm-thick polypropylene film substrate. A highly focused ultrasound beam was transmitted from the rear side of the substrate, and the reflection was received by the same transducer. An Acoustic pulse, its spectrum spreading briefly 100 through 450 MHz, was transmitted. By analyzing the internal reflections in the cell, the distribution of characteristic Acoustic Impedance along the beam direction was determined. Three-dimensional Acoustic Impedance mapping was realized by scanning the transducer, exhibiting the intra-cellular structure including nucleus and cytoskeleton.
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Acoustic Impedance estimation using calibration curve for scanning Acoustic Impedance microscope
2016 International Conference on Knowledge Creation and Intelligent Computing (KCIC), 2016Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Ultrasonic has been used since several decades ago. One of ultrasonic application is used in medical field to observe mechanical properties of target, such as speed of sound, density, Acoustic Impedance, attenuation, etc. Several methods are also available to estimate mechanical property of target. In the previous research, we developed Scanning Acoustic Microscope (SAM). On that research, we proposed a method to estimated Acoustic Impedance by utilizing calibration curve. A calibration curve is established based on echo intensity obtained from calculation of Acoustic propagation. The highest amplitude of a single frequency component is chosen and taken into calculation. The other frequency components are neglected. In this paper, authors propose a method to estimate Acoustic Impedance of target. The Acoustic Impedance is estimated based on calibration curve by considering all frequency components of Acoustic wave. This calculation is then compared to previous research. As a result, Acoustic Impedance of cerebellar tissue of rat are presented by utilizing two calibration curves.
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numerical analysis of ultrasound propagation and reflection intensity for biological Acoustic Impedance microscope
Ultrasonics, 2015Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Abstract This paper proposes a new method for microscopic Acoustic imaging that utilizes the cross sectional Acoustic Impedance of biological soft tissues. In the system, a focused Acoustic beam with a wide band frequency of 30–100 MHz is transmitted across a plastic substrate on the rear side of which a soft tissue object is placed. By scanning the focal point along the surface, a 2-D reflection intensity profile is obtained. In the paper, interpretation of the signal intensity into a characteristic Acoustic Impedance is discussed. Because the Acoustic beam is strongly focused, interpretation assuming vertical incidence may lead to significant error. To determine an accurate calibration curve, a numerical sound field analysis was performed. In these calculations, the reflection intensity from a target with an assumed Acoustic Impedance was compared with that from water, which was used as a reference material. The calibration curve was determined by changing the assumed Acoustic Impedance of the target material. The calibration curve was verified experimentally using saline solution, of which the Acoustic Impedance was known, as the target material. Finally, the cerebellar tissue of a rat was observed to create an Acoustic Impedance micro profile. In the paper, details of the numerical analysis and verification of the observation results will be described.
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Acoustic Impedance microscopy for biological tissue characterization.
Ultrasonics, 2014Co-Authors: Kazuto Kobayashi, Yoshifumi Saijo, Sachiko Yoshida, Naohiro HozumiAbstract:Abstract A new method for two-dimensional Acoustic Impedance imaging for biological tissue characterization with micro-scale resolution was proposed. A biological tissue was placed on a plastic substrate with a thickness of 0.5 mm. A focused Acoustic pulse with a wide frequency band was irradiated from the “rear side” of the substrate. In order to generate the Acoustic wave, an electric pulse with two nanoseconds in width was applied to a PVDF-TrFE type transducer. The component of echo intensity at an appropriate frequency was extracted from the signal received at the same transducer, by performing a time–frequency domain analysis. The spectrum intensity was interpreted into local Acoustic Impedance of the target tissue. The Acoustic Impedance of the substrate was carefully assessed prior to the measurement, since it strongly affects the echo intensity. In addition, a calibration was performed using a reference material of which Acoustic Impedance was known. The reference material was attached on the same substrate at different position in the field of view. An Acoustic Impedance microscopy with 200 × 200 pixels, its typical field of view being 2 × 2 mm, was obtained by scanning the transducer. The development of parallel fiber in cerebella cultures was clearly observed as the contrast in Acoustic Impedance, without staining the specimen. The technique is believed to be a powerful tool for biological tissue characterization, as no staining nor slicing is required.
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Aberration correction for biological Acoustic Impedance microscope
2009 IEEE International Ultrasonics Symposium, 2009Co-Authors: T. Uemura, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji Yamamoto, T. Suzuki, K. Hanai, Yoshifumi SaijoAbstract:This report deals with the scanning Acoustic microscope for imaging cross sectional characteristic Acoustic Impedance of biological soft tissues. A focused pulse wave is transmitted to the object placed on the “rear surface” of a plastic substrate. The reflected signals from the target and reference are interpreted into local Acoustic Impedance. Two-dimensional profile is obtained by scanning the transducer. This method, using a spherical transducer, produces a significant aberration, because the sound speed of the substrate is different from water that is used as a coupling medium. For this reason the spatial resolution is reduced. The spatial resolution was improved by using 3D deconvolution technique, considering the impulse response of the Acoustic system. In addition, as the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. Calibration for Acoustic Impedance was carried out after the deconvolution process, considering the above mentioned oblique incidence.
Naohiro Hozumi - One of the best experts on this subject based on the ideXlab platform.
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Three-dimensional Acoustic Impedance mapping of cultured biological cells.
Ultrasonics, 2019Co-Authors: Naohiro Hozumi, Sachiko Yoshida, Kazuto KobayashiAbstract:Abstract The Acoustic microscope is a powerful tool for the observation of biological matters. Non-invasive in-situ observation can be performed without any staining process. Acoustic microscopy is contrasted by elastic parameters like sound speed and Acoustic Impedance. We have proposed an Acoustic microscope that can acquire three-dimensional Acoustic Impedance profile. The technique was applied to cell-size observation. Glial cells were cultured on a 70 μm-thick polypropylene film substrate. A highly focused ultrasound beam was transmitted from the rear side of the substrate, and the reflection was received by the same transducer. An Acoustic pulse, its spectrum spreading briefly 100 through 450 MHz, was transmitted. By analyzing the internal reflections in the cell, the distribution of characteristic Acoustic Impedance along the beam direction was determined. Three-dimensional Acoustic Impedance mapping was realized by scanning the transducer, exhibiting the intra-cellular structure including nucleus and cytoskeleton.
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Acoustic Impedance estimation using calibration curve for scanning Acoustic Impedance microscope
2016 International Conference on Knowledge Creation and Intelligent Computing (KCIC), 2016Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Ultrasonic has been used since several decades ago. One of ultrasonic application is used in medical field to observe mechanical properties of target, such as speed of sound, density, Acoustic Impedance, attenuation, etc. Several methods are also available to estimate mechanical property of target. In the previous research, we developed Scanning Acoustic Microscope (SAM). On that research, we proposed a method to estimated Acoustic Impedance by utilizing calibration curve. A calibration curve is established based on echo intensity obtained from calculation of Acoustic propagation. The highest amplitude of a single frequency component is chosen and taken into calculation. The other frequency components are neglected. In this paper, authors propose a method to estimate Acoustic Impedance of target. The Acoustic Impedance is estimated based on calibration curve by considering all frequency components of Acoustic wave. This calculation is then compared to previous research. As a result, Acoustic Impedance of cerebellar tissue of rat are presented by utilizing two calibration curves.
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numerical analysis of ultrasound propagation and reflection intensity for biological Acoustic Impedance microscope
Ultrasonics, 2015Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Abstract This paper proposes a new method for microscopic Acoustic imaging that utilizes the cross sectional Acoustic Impedance of biological soft tissues. In the system, a focused Acoustic beam with a wide band frequency of 30–100 MHz is transmitted across a plastic substrate on the rear side of which a soft tissue object is placed. By scanning the focal point along the surface, a 2-D reflection intensity profile is obtained. In the paper, interpretation of the signal intensity into a characteristic Acoustic Impedance is discussed. Because the Acoustic beam is strongly focused, interpretation assuming vertical incidence may lead to significant error. To determine an accurate calibration curve, a numerical sound field analysis was performed. In these calculations, the reflection intensity from a target with an assumed Acoustic Impedance was compared with that from water, which was used as a reference material. The calibration curve was determined by changing the assumed Acoustic Impedance of the target material. The calibration curve was verified experimentally using saline solution, of which the Acoustic Impedance was known, as the target material. Finally, the cerebellar tissue of a rat was observed to create an Acoustic Impedance micro profile. In the paper, details of the numerical analysis and verification of the observation results will be described.
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Acoustic Impedance microscopy for biological tissue characterization.
Ultrasonics, 2014Co-Authors: Kazuto Kobayashi, Yoshifumi Saijo, Sachiko Yoshida, Naohiro HozumiAbstract:Abstract A new method for two-dimensional Acoustic Impedance imaging for biological tissue characterization with micro-scale resolution was proposed. A biological tissue was placed on a plastic substrate with a thickness of 0.5 mm. A focused Acoustic pulse with a wide frequency band was irradiated from the “rear side” of the substrate. In order to generate the Acoustic wave, an electric pulse with two nanoseconds in width was applied to a PVDF-TrFE type transducer. The component of echo intensity at an appropriate frequency was extracted from the signal received at the same transducer, by performing a time–frequency domain analysis. The spectrum intensity was interpreted into local Acoustic Impedance of the target tissue. The Acoustic Impedance of the substrate was carefully assessed prior to the measurement, since it strongly affects the echo intensity. In addition, a calibration was performed using a reference material of which Acoustic Impedance was known. The reference material was attached on the same substrate at different position in the field of view. An Acoustic Impedance microscopy with 200 × 200 pixels, its typical field of view being 2 × 2 mm, was obtained by scanning the transducer. The development of parallel fiber in cerebella cultures was clearly observed as the contrast in Acoustic Impedance, without staining the specimen. The technique is believed to be a powerful tool for biological tissue characterization, as no staining nor slicing is required.
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Aberration correction for biological Acoustic Impedance microscope
2009 IEEE International Ultrasonics Symposium, 2009Co-Authors: T. Uemura, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji Yamamoto, T. Suzuki, K. Hanai, Yoshifumi SaijoAbstract:This report deals with the scanning Acoustic microscope for imaging cross sectional characteristic Acoustic Impedance of biological soft tissues. A focused pulse wave is transmitted to the object placed on the “rear surface” of a plastic substrate. The reflected signals from the target and reference are interpreted into local Acoustic Impedance. Two-dimensional profile is obtained by scanning the transducer. This method, using a spherical transducer, produces a significant aberration, because the sound speed of the substrate is different from water that is used as a coupling medium. For this reason the spatial resolution is reduced. The spatial resolution was improved by using 3D deconvolution technique, considering the impulse response of the Acoustic system. In addition, as the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. Calibration for Acoustic Impedance was carried out after the deconvolution process, considering the above mentioned oblique incidence.
Seiji Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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Acoustic Impedance estimation using calibration curve for scanning Acoustic Impedance microscope
2016 International Conference on Knowledge Creation and Intelligent Computing (KCIC), 2016Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Ultrasonic has been used since several decades ago. One of ultrasonic application is used in medical field to observe mechanical properties of target, such as speed of sound, density, Acoustic Impedance, attenuation, etc. Several methods are also available to estimate mechanical property of target. In the previous research, we developed Scanning Acoustic Microscope (SAM). On that research, we proposed a method to estimated Acoustic Impedance by utilizing calibration curve. A calibration curve is established based on echo intensity obtained from calculation of Acoustic propagation. The highest amplitude of a single frequency component is chosen and taken into calculation. The other frequency components are neglected. In this paper, authors propose a method to estimate Acoustic Impedance of target. The Acoustic Impedance is estimated based on calibration curve by considering all frequency components of Acoustic wave. This calculation is then compared to previous research. As a result, Acoustic Impedance of cerebellar tissue of rat are presented by utilizing two calibration curves.
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numerical analysis of ultrasound propagation and reflection intensity for biological Acoustic Impedance microscope
Ultrasonics, 2015Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Abstract This paper proposes a new method for microscopic Acoustic imaging that utilizes the cross sectional Acoustic Impedance of biological soft tissues. In the system, a focused Acoustic beam with a wide band frequency of 30–100 MHz is transmitted across a plastic substrate on the rear side of which a soft tissue object is placed. By scanning the focal point along the surface, a 2-D reflection intensity profile is obtained. In the paper, interpretation of the signal intensity into a characteristic Acoustic Impedance is discussed. Because the Acoustic beam is strongly focused, interpretation assuming vertical incidence may lead to significant error. To determine an accurate calibration curve, a numerical sound field analysis was performed. In these calculations, the reflection intensity from a target with an assumed Acoustic Impedance was compared with that from water, which was used as a reference material. The calibration curve was determined by changing the assumed Acoustic Impedance of the target material. The calibration curve was verified experimentally using saline solution, of which the Acoustic Impedance was known, as the target material. Finally, the cerebellar tissue of a rat was observed to create an Acoustic Impedance micro profile. In the paper, details of the numerical analysis and verification of the observation results will be described.
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Aberration correction for biological Acoustic Impedance microscope
2009 IEEE International Ultrasonics Symposium, 2009Co-Authors: T. Uemura, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji Yamamoto, T. Suzuki, K. Hanai, Yoshifumi SaijoAbstract:This report deals with the scanning Acoustic microscope for imaging cross sectional characteristic Acoustic Impedance of biological soft tissues. A focused pulse wave is transmitted to the object placed on the “rear surface” of a plastic substrate. The reflected signals from the target and reference are interpreted into local Acoustic Impedance. Two-dimensional profile is obtained by scanning the transducer. This method, using a spherical transducer, produces a significant aberration, because the sound speed of the substrate is different from water that is used as a coupling medium. For this reason the spatial resolution is reduced. The spatial resolution was improved by using 3D deconvolution technique, considering the impulse response of the Acoustic system. In addition, as the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. Calibration for Acoustic Impedance was carried out after the deconvolution process, considering the above mentioned oblique incidence.
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9D-1 Precise Calibration for Biological Acoustic Impedance Microscope
2007 IEEE Ultrasonics Symposium Proceedings, 2007Co-Authors: Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji Yamamoto, S. Terauchi, Masayuki Nagao, A. Nakano, Yoshifumi SaijoAbstract:This report deals with the scanning Acoustic microscope for imaging cross sectional Acoustic Impedance of biological soft tissues. A focused Acoustic beam with a wide frequency range up to about 100 MHz was transmitted to the tissue object in contact with the "rear surface" of plastic substrate. The reflected signals from the target and reference are interpreted into local Acoustic Impedance. Two-dimensional profile is obtained by scanning the transducer. As the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. The error in estimated Acoustic Impedance assuming vertical incidence was discussed. The error is not negligible if the angle of focusing is large, or the Acoustic Impedance of the reference material is far different from the target. However it can be compensated, if the beam pattern and Acoustic parameters of coupling medium and substrate were known. The improvement of precision brought by the compensation was ensured by using a droplet of saline solution of which Acoustic Impedance was known. Finally, a cerebellum tissue of rat was observed with a good precision.
Sachiko Yoshida - One of the best experts on this subject based on the ideXlab platform.
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Three-dimensional Acoustic Impedance mapping of cultured biological cells.
Ultrasonics, 2019Co-Authors: Naohiro Hozumi, Sachiko Yoshida, Kazuto KobayashiAbstract:Abstract The Acoustic microscope is a powerful tool for the observation of biological matters. Non-invasive in-situ observation can be performed without any staining process. Acoustic microscopy is contrasted by elastic parameters like sound speed and Acoustic Impedance. We have proposed an Acoustic microscope that can acquire three-dimensional Acoustic Impedance profile. The technique was applied to cell-size observation. Glial cells were cultured on a 70 μm-thick polypropylene film substrate. A highly focused ultrasound beam was transmitted from the rear side of the substrate, and the reflection was received by the same transducer. An Acoustic pulse, its spectrum spreading briefly 100 through 450 MHz, was transmitted. By analyzing the internal reflections in the cell, the distribution of characteristic Acoustic Impedance along the beam direction was determined. Three-dimensional Acoustic Impedance mapping was realized by scanning the transducer, exhibiting the intra-cellular structure including nucleus and cytoskeleton.
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Acoustic Impedance estimation using calibration curve for scanning Acoustic Impedance microscope
2016 International Conference on Knowledge Creation and Intelligent Computing (KCIC), 2016Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Ultrasonic has been used since several decades ago. One of ultrasonic application is used in medical field to observe mechanical properties of target, such as speed of sound, density, Acoustic Impedance, attenuation, etc. Several methods are also available to estimate mechanical property of target. In the previous research, we developed Scanning Acoustic Microscope (SAM). On that research, we proposed a method to estimated Acoustic Impedance by utilizing calibration curve. A calibration curve is established based on echo intensity obtained from calculation of Acoustic propagation. The highest amplitude of a single frequency component is chosen and taken into calculation. The other frequency components are neglected. In this paper, authors propose a method to estimate Acoustic Impedance of target. The Acoustic Impedance is estimated based on calibration curve by considering all frequency components of Acoustic wave. This calculation is then compared to previous research. As a result, Acoustic Impedance of cerebellar tissue of rat are presented by utilizing two calibration curves.
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numerical analysis of ultrasound propagation and reflection intensity for biological Acoustic Impedance microscope
Ultrasonics, 2015Co-Authors: Agus Indra Gunawan, Yoshifumi Saijo, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji YamamotoAbstract:Abstract This paper proposes a new method for microscopic Acoustic imaging that utilizes the cross sectional Acoustic Impedance of biological soft tissues. In the system, a focused Acoustic beam with a wide band frequency of 30–100 MHz is transmitted across a plastic substrate on the rear side of which a soft tissue object is placed. By scanning the focal point along the surface, a 2-D reflection intensity profile is obtained. In the paper, interpretation of the signal intensity into a characteristic Acoustic Impedance is discussed. Because the Acoustic beam is strongly focused, interpretation assuming vertical incidence may lead to significant error. To determine an accurate calibration curve, a numerical sound field analysis was performed. In these calculations, the reflection intensity from a target with an assumed Acoustic Impedance was compared with that from water, which was used as a reference material. The calibration curve was determined by changing the assumed Acoustic Impedance of the target material. The calibration curve was verified experimentally using saline solution, of which the Acoustic Impedance was known, as the target material. Finally, the cerebellar tissue of a rat was observed to create an Acoustic Impedance micro profile. In the paper, details of the numerical analysis and verification of the observation results will be described.
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Acoustic Impedance microscopy for biological tissue characterization.
Ultrasonics, 2014Co-Authors: Kazuto Kobayashi, Yoshifumi Saijo, Sachiko Yoshida, Naohiro HozumiAbstract:Abstract A new method for two-dimensional Acoustic Impedance imaging for biological tissue characterization with micro-scale resolution was proposed. A biological tissue was placed on a plastic substrate with a thickness of 0.5 mm. A focused Acoustic pulse with a wide frequency band was irradiated from the “rear side” of the substrate. In order to generate the Acoustic wave, an electric pulse with two nanoseconds in width was applied to a PVDF-TrFE type transducer. The component of echo intensity at an appropriate frequency was extracted from the signal received at the same transducer, by performing a time–frequency domain analysis. The spectrum intensity was interpreted into local Acoustic Impedance of the target tissue. The Acoustic Impedance of the substrate was carefully assessed prior to the measurement, since it strongly affects the echo intensity. In addition, a calibration was performed using a reference material of which Acoustic Impedance was known. The reference material was attached on the same substrate at different position in the field of view. An Acoustic Impedance microscopy with 200 × 200 pixels, its typical field of view being 2 × 2 mm, was obtained by scanning the transducer. The development of parallel fiber in cerebella cultures was clearly observed as the contrast in Acoustic Impedance, without staining the specimen. The technique is believed to be a powerful tool for biological tissue characterization, as no staining nor slicing is required.
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Aberration correction for biological Acoustic Impedance microscope
2009 IEEE International Ultrasonics Symposium, 2009Co-Authors: T. Uemura, Naohiro Hozumi, Sachiko Yoshida, Kazuto Kobayashi, Seiji Yamamoto, T. Suzuki, K. Hanai, Yoshifumi SaijoAbstract:This report deals with the scanning Acoustic microscope for imaging cross sectional characteristic Acoustic Impedance of biological soft tissues. A focused pulse wave is transmitted to the object placed on the “rear surface” of a plastic substrate. The reflected signals from the target and reference are interpreted into local Acoustic Impedance. Two-dimensional profile is obtained by scanning the transducer. This method, using a spherical transducer, produces a significant aberration, because the sound speed of the substrate is different from water that is used as a coupling medium. For this reason the spatial resolution is reduced. The spatial resolution was improved by using 3D deconvolution technique, considering the impulse response of the Acoustic system. In addition, as the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. Calibration for Acoustic Impedance was carried out after the deconvolution process, considering the above mentioned oblique incidence.
Mark Sheplak - One of the best experts on this subject based on the ideXlab platform.
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modal decomposition method for Acoustic Impedance testing in square ducts
Journal of the Acoustical Society of America, 2006Co-Authors: Todd Schultz, Louis N Cattafesta, Mark SheplakAbstract:Accurate duct Acoustic propagation models are required to predict and reduce aircraft engine noise. These models ultimately rely on measurements of the Acoustic Impedance to characterize candidate engine nacelle liners. This research effort increases the frequency range of normal-incidence Acoustic Impedance testing in square ducts by extending the standard two-microphone method (TMM), which is limited to plane wave propagation, to include higher-order modes. The modal decomposition method (MDM) presented includes four normal modes in the model of the sound field, thus increasing the bandwidth from 6.7to13.5kHz for a 25.4mm square waveguide. The MDM characterizes the test specimen for normal- and oblique-incident Acoustic Impedance and mode scattering coefficients. The MDM is first formulated and then applied to the measurement of the reflection coefficient matrix for a ceramic tubular specimen. The experimental results are consistent with results from the TMM for the same specimen to within the 95% confi...
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modal decomposition method for Acoustic Impedance testing in square ducts
Journal of the Acoustical Society of America, 2006Co-Authors: Todd Schultz, Louis N Cattafesta, Mark SheplakAbstract:Accurate duct Acoustic propagation models are required to predict and reduce aircraft engine noise. These models ultimately rely on measurements of the Acoustic Impedance to characterize candidate engine nacelle liners. This research effort increases the frequency range of normal-incidence Acoustic Impedance testing in square ducts by extending the standard two-microphone method (TMM), which is limited to plane wave propagation, to include higher-order modes. The modal decomposition method (MDM) presented includes four normal modes in the model of the sound field, thus increasing the bandwidth from 6.7 to 13.5 kHz for a 25.4 mm square waveguide. The MDM characterizes the test specimen for normal- and oblique-incident Acoustic Impedance and mode scattering coefficients. The MDM is first formulated and then applied to the measurement of the reflection coefficient matrix for a ceramic tubular specimen. The experimental results are consistent with results from the TMM for the same specimen to within the 95% confidence intervals for the TMM. The MDM results show a series of resonances for the ceramic tubular material exhibiting a monotonic decrease in the resonant peaks of the Acoustic resistance with increasing frequency, resembling a rigidly-terminated viscous tube, and also evidence of mode scattering is visible at the higher frequencies.
