This paper investigated a cell patterning technique using ultrasound vibration. The ultrasound cell culture dish consisted of a culture dish with a glass bottom and a glass disc with an ultrasound transducer that generated a resonance flexural vibration mode on the bottom of the dish. HeLa cells were used as adhesives cells, and the growth of cells on the dish was observed under ultrasound excitation for 24 hours. The vibration amplitude was largest at the center of the dish, and the axisymmetric resonance flexural vibration mode with three concentric nodal circles and no nodal line was generated on the bottom of the dish. Large vibrations inhibited the cell growth. The distributions of the sound pressure amplitude and the acoustic radiation force in the culture medium were calculated with finite element analysis and it was found that the cell growth depended strongly on both the acoustic field in the culture medium and the vibration distribution of the dish. The ultrasound vibrations did not affect the viability of the cells, and the cell growth could be controlled by the flexural vibration of the cultured dish.This paper investigated a cell patterning technique using ultrasound vibration. The ultrasound cell culture dish consisted of a culture dish with a glass bottom and a glass disc with an ultrasound transducer that generated a resonance flexural vibration mode on the bottom of the dish. HeLa cells were used as adhesives cells, and the growth of cells on the dish was observed under ultrasound excitation for 24 hours. The vibration amplitude was largest at the center of the dish, and the axisymmetric resonance flexural vibration mode with three concentric nodal circles and no nodal line was generated on the bottom of the dish. Large vibrations inhibited the cell growth. The distributions of the sound pressure amplitude and the acoustic radiation force in the culture medium were calculated with finite element analysis and it was found that the cell growth depended strongly on both the acoustic field in the culture medium and the vibration distribution of the dish. The ultrasound vibrations did not affect the v...
{"title":"Patterning technique of adhesive cells using ultrasound flexural vibration","authors":"D. Koyama, Kentaro Tani, Koji Fujiwara","doi":"10.1121/2.0000846","DOIUrl":"https://doi.org/10.1121/2.0000846","url":null,"abstract":"This paper investigated a cell patterning technique using ultrasound vibration. The ultrasound cell culture dish consisted of a culture dish with a glass bottom and a glass disc with an ultrasound transducer that generated a resonance flexural vibration mode on the bottom of the dish. HeLa cells were used as adhesives cells, and the growth of cells on the dish was observed under ultrasound excitation for 24 hours. The vibration amplitude was largest at the center of the dish, and the axisymmetric resonance flexural vibration mode with three concentric nodal circles and no nodal line was generated on the bottom of the dish. Large vibrations inhibited the cell growth. The distributions of the sound pressure amplitude and the acoustic radiation force in the culture medium were calculated with finite element analysis and it was found that the cell growth depended strongly on both the acoustic field in the culture medium and the vibration distribution of the dish. The ultrasound vibrations did not affect the viability of the cells, and the cell growth could be controlled by the flexural vibration of the cultured dish.This paper investigated a cell patterning technique using ultrasound vibration. The ultrasound cell culture dish consisted of a culture dish with a glass bottom and a glass disc with an ultrasound transducer that generated a resonance flexural vibration mode on the bottom of the dish. HeLa cells were used as adhesives cells, and the growth of cells on the dish was observed under ultrasound excitation for 24 hours. The vibration amplitude was largest at the center of the dish, and the axisymmetric resonance flexural vibration mode with three concentric nodal circles and no nodal line was generated on the bottom of the dish. Large vibrations inhibited the cell growth. The distributions of the sound pressure amplitude and the acoustic radiation force in the culture medium were calculated with finite element analysis and it was found that the cell growth depended strongly on both the acoustic field in the culture medium and the vibration distribution of the dish. The ultrasound vibrations did not affect the v...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86196464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Experiments are performed to demonstrate emergence of shocked and unshocked thermoacoustic oscillations in a circular, looped tube filled with an atmospheric air. A pair of stacks identical in geometry is installed at diametrically opposite positions, and each stack is sandwiched by hot and cold heat exchangers. The hot heat exchangers are heated by electric heaters evenly for the same temperature gradient to be imposed on the stacks. The cold heat exchangers are cooled by circulating a tap water to be kept at an ambient temperature. Four types of the stacks are employed to examine influences of stack’s pore width and its porosity on the oscillations. For all stacks, self-excited thermoacoustic oscillations are observed, which propagate in the same sense as the one of the temperature gradient. The oscillations occur in a 1-wave mode where the wavelength corresponds to the loop length. The maximum of the peak-to-peak acoustic pressure is found to attain 15% relative to the atmospheric pressure. Depending on the pair of stacks, shocked or unshocked profiles are observed. Difference in mechanisms leading to the two profiles is examined from a viewpoint of dissonance of eigenfrequencies of the oscillations.Experiments are performed to demonstrate emergence of shocked and unshocked thermoacoustic oscillations in a circular, looped tube filled with an atmospheric air. A pair of stacks identical in geometry is installed at diametrically opposite positions, and each stack is sandwiched by hot and cold heat exchangers. The hot heat exchangers are heated by electric heaters evenly for the same temperature gradient to be imposed on the stacks. The cold heat exchangers are cooled by circulating a tap water to be kept at an ambient temperature. Four types of the stacks are employed to examine influences of stack’s pore width and its porosity on the oscillations. For all stacks, self-excited thermoacoustic oscillations are observed, which propagate in the same sense as the one of the temperature gradient. The oscillations occur in a 1-wave mode where the wavelength corresponds to the loop length. The maximum of the peak-to-peak acoustic pressure is found to attain 15% relative to the atmospheric pressure. Depending o...
{"title":"Shocked and unshocked thermoacoustic oscillations in a looped tube","authors":"Nobumasa Sugimoto, Keisuke Minamigawa","doi":"10.1121/2.0000847","DOIUrl":"https://doi.org/10.1121/2.0000847","url":null,"abstract":"Experiments are performed to demonstrate emergence of shocked and unshocked thermoacoustic oscillations in a circular, looped tube filled with an atmospheric air. A pair of stacks identical in geometry is installed at diametrically opposite positions, and each stack is sandwiched by hot and cold heat exchangers. The hot heat exchangers are heated by electric heaters evenly for the same temperature gradient to be imposed on the stacks. The cold heat exchangers are cooled by circulating a tap water to be kept at an ambient temperature. Four types of the stacks are employed to examine influences of stack’s pore width and its porosity on the oscillations. For all stacks, self-excited thermoacoustic oscillations are observed, which propagate in the same sense as the one of the temperature gradient. The oscillations occur in a 1-wave mode where the wavelength corresponds to the loop length. The maximum of the peak-to-peak acoustic pressure is found to attain 15% relative to the atmospheric pressure. Depending on the pair of stacks, shocked or unshocked profiles are observed. Difference in mechanisms leading to the two profiles is examined from a viewpoint of dissonance of eigenfrequencies of the oscillations.Experiments are performed to demonstrate emergence of shocked and unshocked thermoacoustic oscillations in a circular, looped tube filled with an atmospheric air. A pair of stacks identical in geometry is installed at diametrically opposite positions, and each stack is sandwiched by hot and cold heat exchangers. The hot heat exchangers are heated by electric heaters evenly for the same temperature gradient to be imposed on the stacks. The cold heat exchangers are cooled by circulating a tap water to be kept at an ambient temperature. Four types of the stacks are employed to examine influences of stack’s pore width and its porosity on the oscillations. For all stacks, self-excited thermoacoustic oscillations are observed, which propagate in the same sense as the one of the temperature gradient. The oscillations occur in a 1-wave mode where the wavelength corresponds to the loop length. The maximum of the peak-to-peak acoustic pressure is found to attain 15% relative to the atmospheric pressure. Depending o...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74965020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Published work on dolphin sonar is utilized to model the short transient “clicks” used by the small-toothed whales for foraging, etc., in order to determine whether or not nonlinear acoustical effects play a role in dolphin sonar. Echolocation sound production in the bottlenose dolphin and the resulting underwater sonar signals is briefly reviewed. Nonlinear acoustic modeling with the Khokhlov–Zabolotskaya–Kuznetsov (KZK) nonlinear parabolic wave equation is described, along with the procedures used to employ measured signatures in modeling computations. Results for the bottlenose dolphin as well as several other species of small toothed whales indicate that propagating nonlinear acoustical effects in the water medium are not significant.
{"title":"Dolphin sonar transmissions and nonlinear effects","authors":"T. Muir, J. A. Shooter, M. Hamilton","doi":"10.1121/2.0000845","DOIUrl":"https://doi.org/10.1121/2.0000845","url":null,"abstract":"Published work on dolphin sonar is utilized to model the short transient “clicks” used by the small-toothed whales for foraging, etc., in order to determine whether or not nonlinear acoustical effects play a role in dolphin sonar. Echolocation sound production in the bottlenose dolphin and the resulting underwater sonar signals is briefly reviewed. Nonlinear acoustic modeling with the Khokhlov–Zabolotskaya–Kuznetsov (KZK) nonlinear parabolic wave equation is described, along with the procedures used to employ measured signatures in modeling computations. Results for the bottlenose dolphin as well as several other species of small toothed whales indicate that propagating nonlinear acoustical effects in the water medium are not significant.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"279 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77836555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Berjamin, G. Chiavassa, N. Favrie, B. Lombard, E. Sarrouy
Rocks and concrete are known to soften under a dynamic loading, i.e. the speed of sound diminishes with forcing amplitudes. To reproduce this behavior, an internal-variable model of continuum is proposed. It is composed of a constitutive law for the stress and an evolution equation for the internal variable. Nonlinear viscoelasticity of Zener type is accounted for by using additional internal variables. The proposed system of partial differential equations is solved numerically using finite-volume methods. The numerical tool is used to reproduce qualitatively Nonlinear Resonance Ultrasound Spectroscopy (NRUS) and Dynamic Acoustoelastic Testing (DAET) experiments. A frequency-domain approach based on finite elements, harmonic balance and numerical continuation is compared to the time-domain method. This approach is promising for upcoming experimental validations with respect to resonance experiments.
{"title":"Internal-variable modeling of solids with slow dynamics: Wave propagation and resonance simulations","authors":"H. Berjamin, G. Chiavassa, N. Favrie, B. Lombard, E. Sarrouy","doi":"10.1121/2.0000844","DOIUrl":"https://doi.org/10.1121/2.0000844","url":null,"abstract":"Rocks and concrete are known to soften under a dynamic loading, i.e. the speed of sound diminishes with forcing amplitudes. To reproduce this behavior, an internal-variable model of continuum is proposed. It is composed of a constitutive law for the stress and an evolution equation for the internal variable. Nonlinear viscoelasticity of Zener type is accounted for by using additional internal variables. The proposed system of partial differential equations is solved numerically using finite-volume methods. The numerical tool is used to reproduce qualitatively Nonlinear Resonance Ultrasound Spectroscopy (NRUS) and Dynamic Acoustoelastic Testing (DAET) experiments. A frequency-domain approach based on finite elements, harmonic balance and numerical continuation is compared to the time-domain method. This approach is promising for upcoming experimental validations with respect to resonance experiments.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"216 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86646556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Vibro-Acoustic Modulation (VAM) method utilizes nonlinear interaction of a high frequency ultrasonic wave (carrier signal) with frequency ω and a low frequency modulating vibration with frequency Ω << ω, in the presence of various flaws such as fatigue and stress-corrosion cracks, disbonds, etc. Most of the reported VAM studies correlate flaw presence and growth with the increase in the Modulation Index (MI) defined in the spectral domain as the ratio of the side-band spectral components at frequencies ω±Ω to the amplitude of the carrier. This approach, however, does not differentiate between amplitude, AM, or frequency, FM, modulations contributing to the MI. It has been assumed that the prevailing modulation is AM due to contact-type nonlinear mechanisms. However, there could be other mechanisms leading to phase/frequency modulation. The present study aims to develop an algorithm of AM/FM separation specifically for the VAM method. It is shown that the commonly used Hilbert Transform (HT) separation may not work for a typical VAM scenario. The developed In-phase/Quadrature Homodyne Separation algorithm addresses HT shortcomings. The algorithm has been tested both numerically and experimentally (for fatigue crack evolution) showing FM dominance at initial micro-crack growth stages and transition to AM dominance during macro-crack formation.The Vibro-Acoustic Modulation (VAM) method utilizes nonlinear interaction of a high frequency ultrasonic wave (carrier signal) with frequency ω and a low frequency modulating vibration with frequency Ω << ω, in the presence of various flaws such as fatigue and stress-corrosion cracks, disbonds, etc. Most of the reported VAM studies correlate flaw presence and growth with the increase in the Modulation Index (MI) defined in the spectral domain as the ratio of the side-band spectral components at frequencies ω±Ω to the amplitude of the carrier. This approach, however, does not differentiate between amplitude, AM, or frequency, FM, modulations contributing to the MI. It has been assumed that the prevailing modulation is AM due to contact-type nonlinear mechanisms. However, there could be other mechanisms leading to phase/frequency modulation. The present study aims to develop an algorithm of AM/FM separation specifically for the VAM method. It is shown that the commonly used Hilbert Transform (HT) separation...
{"title":"Separation of amplitude and frequency modulations in Vibro-Acoustic Modulation Nondestructive Testing Method","authors":"D. Donskoy, M. Ramezani","doi":"10.1121/2.0000831","DOIUrl":"https://doi.org/10.1121/2.0000831","url":null,"abstract":"The Vibro-Acoustic Modulation (VAM) method utilizes nonlinear interaction of a high frequency ultrasonic wave (carrier signal) with frequency ω and a low frequency modulating vibration with frequency Ω << ω, in the presence of various flaws such as fatigue and stress-corrosion cracks, disbonds, etc. Most of the reported VAM studies correlate flaw presence and growth with the increase in the Modulation Index (MI) defined in the spectral domain as the ratio of the side-band spectral components at frequencies ω±Ω to the amplitude of the carrier. This approach, however, does not differentiate between amplitude, AM, or frequency, FM, modulations contributing to the MI. It has been assumed that the prevailing modulation is AM due to contact-type nonlinear mechanisms. However, there could be other mechanisms leading to phase/frequency modulation. The present study aims to develop an algorithm of AM/FM separation specifically for the VAM method. It is shown that the commonly used Hilbert Transform (HT) separation may not work for a typical VAM scenario. The developed In-phase/Quadrature Homodyne Separation algorithm addresses HT shortcomings. The algorithm has been tested both numerically and experimentally (for fatigue crack evolution) showing FM dominance at initial micro-crack growth stages and transition to AM dominance during macro-crack formation.The Vibro-Acoustic Modulation (VAM) method utilizes nonlinear interaction of a high frequency ultrasonic wave (carrier signal) with frequency ω and a low frequency modulating vibration with frequency Ω << ω, in the presence of various flaws such as fatigue and stress-corrosion cracks, disbonds, etc. Most of the reported VAM studies correlate flaw presence and growth with the increase in the Modulation Index (MI) defined in the spectral domain as the ratio of the side-band spectral components at frequencies ω±Ω to the amplitude of the carrier. This approach, however, does not differentiate between amplitude, AM, or frequency, FM, modulations contributing to the MI. It has been assumed that the prevailing modulation is AM due to contact-type nonlinear mechanisms. However, there could be other mechanisms leading to phase/frequency modulation. The present study aims to develop an algorithm of AM/FM separation specifically for the VAM method. It is shown that the commonly used Hilbert Transform (HT) separation...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73672720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study performs the derivation of a nonlinear wave equation for plane progressive quasi-monochromatic waves in a compressible liquid containing many spherical microbubbles that oscillate rapidly due to the pressure wave approaching the bubbles. Main assumptions are as follows: (i) the wave frequency is larger than an eigenfrequency of single bubble oscillations, (ii) the compressibility of the liquid phase is incorporated, and (iii) the effect of viscosity in the gas phase, heat conduction in the gas and liquid phases, phase change across the bubble wall, and thermal conductivities of the gas and liquid, are neglected. The basic equations for bubbly flows are composed of a set of conservation equations of mass and momentum in a two-fluid model, the equation of bubble dynamics, and so on. From the method of multiple scales with appropriate choices of scaling relations of some physical parameters such as wavelength, we can derive the nonlinear Schroedinger (NLS) equation with an attenuation term and som...
{"title":"Quasi-monochromatic weakly nonlinear waves of high frequency exceeding eigenfrequency of bubble oscillations in compressible liquid containing microbubbles","authors":"Takanori Yoshimoto, T. Kanagawa","doi":"10.1121/2.0000819","DOIUrl":"https://doi.org/10.1121/2.0000819","url":null,"abstract":"This study performs the derivation of a nonlinear wave equation for plane progressive quasi-monochromatic waves in a compressible liquid containing many spherical microbubbles that oscillate rapidly due to the pressure wave approaching the bubbles. Main assumptions are as follows: (i) the wave frequency is larger than an eigenfrequency of single bubble oscillations, (ii) the compressibility of the liquid phase is incorporated, and (iii) the effect of viscosity in the gas phase, heat conduction in the gas and liquid phases, phase change across the bubble wall, and thermal conductivities of the gas and liquid, are neglected. The basic equations for bubbly flows are composed of a set of conservation equations of mass and momentum in a two-fluid model, the equation of bubble dynamics, and so on. From the method of multiple scales with appropriate choices of scaling relations of some physical parameters such as wavelength, we can derive the nonlinear Schroedinger (NLS) equation with an attenuation term and som...","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87108263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the present study, to realize low-frequency ultrasound (US) imaging, the application of maximum-length sequence (M-sequence) to the compressed parametric US is attempted to reduce time sidelobes, and the performance is experimentally discussed. A modulated primary US at a carrier frequency of 2.8 MHz was radiated in water to generate a 400-kHz parametric US coded by an M-sequence with a chip length equal to one cycle of a 400-kHz signal, and brass rods were used as targets. Experimental results showed that the pulse compression of parametric US with M-sequence reduced artifacts in image. Moreover, the lateral resolution obtained by the proposed method was improved in comparison with that obtained by the compressed-chirped parametric US with the bandwidth from 100 to 500 kHz. These results suggest that the application of M-sequence is well-suited for the parametric US imaging with improved artifacts and lateral resolution.
{"title":"Low-frequency parametric ultrasound imaging using pulse compression with maximum-length sequence excitation","authors":"H. Nomura, Riku Nishioka","doi":"10.1121/2.0000840","DOIUrl":"https://doi.org/10.1121/2.0000840","url":null,"abstract":"In the present study, to realize low-frequency ultrasound (US) imaging, the application of maximum-length sequence (M-sequence) to the compressed parametric US is attempted to reduce time sidelobes, and the performance is experimentally discussed. A modulated primary US at a carrier frequency of 2.8 MHz was radiated in water to generate a 400-kHz parametric US coded by an M-sequence with a chip length equal to one cycle of a 400-kHz signal, and brass rods were used as targets. Experimental results showed that the pulse compression of parametric US with M-sequence reduced artifacts in image. Moreover, the lateral resolution obtained by the proposed method was improved in comparison with that obtained by the compressed-chirped parametric US with the bandwidth from 100 to 500 kHz. These results suggest that the application of M-sequence is well-suited for the parametric US imaging with improved artifacts and lateral resolution.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83502605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A three-dimensional, longitudinally invariant, finite element model of acoustic propagation and reverberation in an ice-covered shallow water waveguide has been developed. The ice is modeled as both an elastic medium and a pressure release surface. Transmission loss levels are calculated and compared for both representations of ice. Using Fourier synthesis, the frequency-domain acoustic pressure results are transformed into the time domain, and reverberation levels are then compared for both representations of ice. The time-domain results show differences between each ice representation that are not captured in the frequency domain. Finally, some possible explanations are presented for these model differences, including compressional-to-shear wave conversion at the ice-water interface and steep incident angle scattering from the ice.A three-dimensional, longitudinally invariant, finite element model of acoustic propagation and reverberation in an ice-covered shallow water waveguide has been developed. The ice is modeled as both an elastic medium and a pressure release surface. Transmission loss levels are calculated and compared for both representations of ice. Using Fourier synthesis, the frequency-domain acoustic pressure results are transformed into the time domain, and reverberation levels are then compared for both representations of ice. The time-domain results show differences between each ice representation that are not captured in the frequency domain. Finally, some possible explanations are presented for these model differences, including compressional-to-shear wave conversion at the ice-water interface and steep incident angle scattering from the ice.
{"title":"Modeling acoustic wave propagation and reverberation in an ice covered environment using finite element analysis","authors":"B. Simon, M. Isakson, M. Ballard","doi":"10.1121/2.0000842","DOIUrl":"https://doi.org/10.1121/2.0000842","url":null,"abstract":"A three-dimensional, longitudinally invariant, finite element model of acoustic propagation and reverberation in an ice-covered shallow water waveguide has been developed. The ice is modeled as both an elastic medium and a pressure release surface. Transmission loss levels are calculated and compared for both representations of ice. Using Fourier synthesis, the frequency-domain acoustic pressure results are transformed into the time domain, and reverberation levels are then compared for both representations of ice. The time-domain results show differences between each ice representation that are not captured in the frequency domain. Finally, some possible explanations are presented for these model differences, including compressional-to-shear wave conversion at the ice-water interface and steep incident angle scattering from the ice.A three-dimensional, longitudinally invariant, finite element model of acoustic propagation and reverberation in an ice-covered shallow water waveguide has been developed. The ice is modeled as both an elastic medium and a pressure release surface. Transmission loss levels are calculated and compared for both representations of ice. Using Fourier synthesis, the frequency-domain acoustic pressure results are transformed into the time domain, and reverberation levels are then compared for both representations of ice. The time-domain results show differences between each ice representation that are not captured in the frequency domain. Finally, some possible explanations are presented for these model differences, including compressional-to-shear wave conversion at the ice-water interface and steep incident angle scattering from the ice.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76146520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Applied Research Laboratories at the University of Texas at Austin (ARL:UT) deployed two passive acoustic recording systems along the 150-m isobath of the Chukchi Shelf during the 2016-2017 Canada Basin Acoustic Propagation Experiment (CANAPE). The first system was a single-hydrophone recorder located on the seafloor, while the Persistent Acoustic Observation System (PECOS) contained a horizontal line array of hydrophones along the seabed and a vertical line array spanning a portion of the water column. The systems were deployed and recovered during open-water conditions, but remained in place during the ice-formation, ice-covered, and ice-melt time periods. This work presents initial findings of the statisti-cal ambient noise levels during the yearlong experiment and presents two examples of the dynamic noise environment present during the recordings.The Applied Research Laboratories at the University of Texas at Austin (ARL:UT) deployed two passive acoustic recording systems along the 150-m isobath of the Chukchi Shelf during the 2016-2017 Canada Basin Acoustic Propagation Experiment (CANAPE). The first system was a single-hydrophone recorder located on the seafloor, while the Persistent Acoustic Observation System (PECOS) contained a horizontal line array of hydrophones along the seabed and a vertical line array spanning a portion of the water column. The systems were deployed and recovered during open-water conditions, but remained in place during the ice-formation, ice-covered, and ice-melt time periods. This work presents initial findings of the statisti-cal ambient noise levels during the yearlong experiment and presents two examples of the dynamic noise environment present during the recordings.
{"title":"Properties of the ambient noise field at the 150-m isobath during the Canada Basin Acoustic Propagation Experiment","authors":"J. Sagers, M. Ballard","doi":"10.1121/2.0000839","DOIUrl":"https://doi.org/10.1121/2.0000839","url":null,"abstract":"The Applied Research Laboratories at the University of Texas at Austin (ARL:UT) deployed two passive acoustic recording systems along the 150-m isobath of the Chukchi Shelf during the 2016-2017 Canada Basin Acoustic Propagation Experiment (CANAPE). The first system was a single-hydrophone recorder located on the seafloor, while the Persistent Acoustic Observation System (PECOS) contained a horizontal line array of hydrophones along the seabed and a vertical line array spanning a portion of the water column. The systems were deployed and recovered during open-water conditions, but remained in place during the ice-formation, ice-covered, and ice-melt time periods. This work presents initial findings of the statisti-cal ambient noise levels during the yearlong experiment and presents two examples of the dynamic noise environment present during the recordings.The Applied Research Laboratories at the University of Texas at Austin (ARL:UT) deployed two passive acoustic recording systems along the 150-m isobath of the Chukchi Shelf during the 2016-2017 Canada Basin Acoustic Propagation Experiment (CANAPE). The first system was a single-hydrophone recorder located on the seafloor, while the Persistent Acoustic Observation System (PECOS) contained a horizontal line array of hydrophones along the seabed and a vertical line array spanning a portion of the water column. The systems were deployed and recovered during open-water conditions, but remained in place during the ice-formation, ice-covered, and ice-melt time periods. This work presents initial findings of the statisti-cal ambient noise levels during the yearlong experiment and presents two examples of the dynamic noise environment present during the recordings.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83692832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The point defects in the spectra of photoluminescence of Lithium niobate (LN) and Lithium tantalate (LT) can be categorized as noble gases, heavy metals, and others. The distribution of charged defects (DCD) reveals peaks and valleys in a direction perpendicular to the z-axis, in both single crystals (SC) and periodically poled (PP) crystals. The distance between consecutive peaks and valleys equals the length of a ferroelectric domain in PPLT. The position of the ferroelectric domain wall with respect to point defects extrema is different in PPLT in comparison to PPLN. The DCD influences acousto-electric properties including electromechanical transduction (EMT) and electromechanical coupling coefficient (ECC), in a direction perpendicular to the z-axis. The results may be used to explain nonclassical nonlinearity in LN and LT crystals.The point defects in the spectra of photoluminescence of Lithium niobate (LN) and Lithium tantalate (LT) can be categorized as noble gases, heavy metals, and others. The distribution of charged defects (DCD) reveals peaks and valleys in a direction perpendicular to the z-axis, in both single crystals (SC) and periodically poled (PP) crystals. The distance between consecutive peaks and valleys equals the length of a ferroelectric domain in PPLT. The position of the ferroelectric domain wall with respect to point defects extrema is different in PPLT in comparison to PPLN. The DCD influences acousto-electric properties including electromechanical transduction (EMT) and electromechanical coupling coefficient (ECC), in a direction perpendicular to the z-axis. The results may be used to explain nonclassical nonlinearity in LN and LT crystals.
{"title":"Point defects in ZX-cut Lithium niobate and Lithium tantalate and their influence on acousto-electric properties","authors":"C. Chatterjee, Daniel Miller, I. Ostrovskii","doi":"10.1121/2.0000834","DOIUrl":"https://doi.org/10.1121/2.0000834","url":null,"abstract":"The point defects in the spectra of photoluminescence of Lithium niobate (LN) and Lithium tantalate (LT) can be categorized as noble gases, heavy metals, and others. The distribution of charged defects (DCD) reveals peaks and valleys in a direction perpendicular to the z-axis, in both single crystals (SC) and periodically poled (PP) crystals. The distance between consecutive peaks and valleys equals the length of a ferroelectric domain in PPLT. The position of the ferroelectric domain wall with respect to point defects extrema is different in PPLT in comparison to PPLN. The DCD influences acousto-electric properties including electromechanical transduction (EMT) and electromechanical coupling coefficient (ECC), in a direction perpendicular to the z-axis. The results may be used to explain nonclassical nonlinearity in LN and LT crystals.The point defects in the spectra of photoluminescence of Lithium niobate (LN) and Lithium tantalate (LT) can be categorized as noble gases, heavy metals, and others. The distribution of charged defects (DCD) reveals peaks and valleys in a direction perpendicular to the z-axis, in both single crystals (SC) and periodically poled (PP) crystals. The distance between consecutive peaks and valleys equals the length of a ferroelectric domain in PPLT. The position of the ferroelectric domain wall with respect to point defects extrema is different in PPLT in comparison to PPLN. The DCD influences acousto-electric properties including electromechanical transduction (EMT) and electromechanical coupling coefficient (ECC), in a direction perpendicular to the z-axis. The results may be used to explain nonclassical nonlinearity in LN and LT crystals.","PeriodicalId":20469,"journal":{"name":"Proc. Meet. Acoust.","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78281017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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