Acoustic radiation force(ARF), as an important particle manipulation method, has been extensively studied in recent years. With the introduction of the concept of “acoustic tweezers”, negative acoustic radiation has...Acoustic radiation force(ARF), as an important particle manipulation method, has been extensively studied in recent years. With the introduction of the concept of “acoustic tweezers”, negative acoustic radiation has become a research hotspot. In this paper, a scheme of realizing negative ARF based on the multiple-layered spherical structure design is proposed. The specific structure and design idea are presented. Detailed theoretical calculation analysis is carried out.Numerical simulations have been performed to verify the correctness of this prediction. The conjecture that the suppression of backscattering can achieve negative ARF is verified concretely, which greatly expands the application prospect and design ideas of the ARF. This work has laid a theoretical foundation for realizing precise control of the structure.展开更多
Thickness measurement plays an important role in the monitoring of pipeline corrosion damage. However, the requirement for prior knowledge of the shear wave velocity in the pipeline material for popular ultrasonic thi...Thickness measurement plays an important role in the monitoring of pipeline corrosion damage. However, the requirement for prior knowledge of the shear wave velocity in the pipeline material for popular ultrasonic thickness measurement limits its widespread application. This paper proposes a method that utilizes cylindrical shear horizontal(SH) guided waves to estimate pipeline thickness without prior knowledge of shear wave velocity. The inversion formulas are derived from the dispersion of higher-order modes with the high-frequency approximation. The waveform of the example problems is simulated using the real-axis integral method. The data points on the dispersion curves are processed in the frequency domain using the wave-number method. These extracted data are then substituted into the derived formulas. The results verify that employing higher-order SH guided waves for the evaluation of thickness and shear wave velocity yields less than1% error. This method can be applied to both metallic and non-metallic pipelines, thus opening new possibilities for health monitoring of pipeline structures.展开更多
The estimation of sparse underwater acoustic(UWA)channels can be regarded as an inference problem involving hidden variables within the Bayesian framework.While the classical sparse Bayesian learning(SBL),derived thro...The estimation of sparse underwater acoustic(UWA)channels can be regarded as an inference problem involving hidden variables within the Bayesian framework.While the classical sparse Bayesian learning(SBL),derived through the expectation maximization(EM)algorithm,has been widely employed for UWA channel estimation,it still differs from the real posterior expectation of channels.In this paper,we propose an approach that combines variational inference(VI)and Markov chain Monte Carlo(MCMC)methods to provide a more accurate posterior estimation.Specifically,the SBL is first re-derived with VI,allowing us to replace the posterior distribution of the hidden variables with a variational distribution.Then,we determine the full conditional probability distribution for each variable in the variational distribution and then iteratively perform random Gibbs sampling in MCMC to converge the Markov chain.The results of simulation and experiment indicate that our estimation method achieves lower mean square error and bit error rate compared to the classic SBL approach.Additionally,it demonstrates an acceptable convergence speed.展开更多
The 9th International Symposium on Modern Acoustics was held in Nanjing,China,on May 19 -22,2012,which has been introduced in an article published in Journal of Nanjing University (Natural Sciences),2012[1].As describ...The 9th International Symposium on Modern Acoustics was held in Nanjing,China,on May 19 -22,2012,which has been introduced in an article published in Journal of Nanjing University (Natural Sciences),2012[1].As described previously,after peer reviewing,a part of the original papers were selected to be published in Journal of Nanjing University(Natural Sciences),which were separated as two issues:the first has already been published in a special issue of the journal in 2012[2~19].展开更多
Nonlinear phononic crystals have attracted great interest because of their unique properties absent in linear phononic crystals.However,few researches have considered the bilinear nonlinearity as well as its consequen...Nonlinear phononic crystals have attracted great interest because of their unique properties absent in linear phononic crystals.However,few researches have considered the bilinear nonlinearity as well as its consequences in acoustic metamaterials.Hence,we introduce bilinear nonlinearity into acoustic metamaterials,and investigate the propagation behaviors of the fundamental and the second harmonic waves in the nonlinear acoustic metamaterials by discretization method,revealing the influence of the system parameters.Furthermore,we investigate the influence of partially periodic nonlinear acoustic metamaterials on the second harmonic wave propagation,and the results suggest that pass-band and band-gap can be transformed into each other under certain conditions.Our findings could be beneficial to the band gap control in nonlinear acoustic metamaterials.展开更多
Acoustic tweezing cytometry(ATC)is a recently developed method for cell mechanics regulation.Tar-geted microbubbles,which are attached to integrins and subsequently the actin cytoskeleton,anchor,amplify and transmit t...Acoustic tweezing cytometry(ATC)is a recently developed method for cell mechanics regulation.Tar-geted microbubbles,which are attached to integrins and subsequently the actin cytoskeleton,anchor,amplify and transmit the mechanical energy in an acoustic field inside the cells,eliciting prominent cy-toskeleton contractile force increases in various cell types.We propose that a mechanochemical con-version mechanism is critical for the high efficiency of ATC to activate cell contractility responses.Our models predict key experimental observations.Moreover,we study the influences of ATC parameters(ul-trasound center frequency,pulse repetition frequency,duty cycle,and acoustic pressure),cell areas,the number of ATC stimuli,and extracellular matrix rigidity on cell contractility responses to ATC.The simu-lation results suggest that it is large molecules,rather than small ions,that facilitate global responses to the local ATC stimulation,and the incorporation of visible stress fiber bundles improves the accuracy of modeling.展开更多
The numerical simulations and experimental results of an ultra-broadband acoustic ventilation barrier composed of periodic unit cells are reported in this paper.Based on multiple mechanisms,including sound absorption ...The numerical simulations and experimental results of an ultra-broadband acoustic ventilation barrier composed of periodic unit cells are reported in this paper.Based on multiple mechanisms,including sound absorption by eigenmodes of the unit cell and sound reflection by a plate structure on upper surface of the unit cell,a single-layer ventilation barrier with broadband sound reduction is designed,and its working bandwidth can reach about 1560 Hz.The experimental results accord well with the simulation results.Furthermore,two types of three-layer ventilation barriers are designed and demonstrated by using the unit cells with different values of a(the length of the hollow square region)and w(the width of the channel between the adjacent cavities),and the bandwidths of both ventilation barriers can increase to 3160 Hz and 3230 Hz,respectively.The designed barrier structures have the advantages of ultra-broadband sound reduction and ventilation,which paves the way to designing high-performance ventilation barriers for the applications in environmental protection and architectural acoustics.展开更多
The shallow-water temperature profile is typically parameterized using a few empirical orthogonal function(EOF)coefficients.However,when the experimental area is poorly known or highly variable,the adaptability of the...The shallow-water temperature profile is typically parameterized using a few empirical orthogonal function(EOF)coefficients.However,when the experimental area is poorly known or highly variable,the adaptability of the EOFs will be significantly reduced.In this study,a new set of basis functions,generated by combining the internal-wave eigenmodes with the average temperature gradient,is developed for characterizing the temperature perturbations.Temperature profiles recorded by a thermistor chain in the South China Sea in 2015 are processed and analyzed.Compared to the EOFs,the new set of basis functions has higher reconstruction accuracy and adaptability;it is also more stable in ocean regions that have internal waves.展开更多
The problem of three-dimensional(3D) acoustic scattering in a complex medium has aroused considerable interest of researchers for many years. An ultrasonic scattered field calculating technique is proposed to study th...The problem of three-dimensional(3D) acoustic scattering in a complex medium has aroused considerable interest of researchers for many years. An ultrasonic scattered field calculating technique is proposed to study the scattering echo from strongly scattered materials in a two-layer medium in this work. Firstly, with the high frequency stationary phase method,the Green's function of two-layer fluid media is derived. And then based on the idea of integral equation discretization,the Green's function method is extended to two-layer fluid media to derive the scattering field expression of defects in a complex medium. With this method, the scattering field of 3D defect in a two-layer medium is calculated and the characteristics of received echoes are studied. The results show that this method is able to solve the scattering P wave field of 3D defect with arbitrary shape at any scattering intensity in two-layer media. Considering the circumstance of waterimmersion ultrasonic non-destructive test(NDT), the scattering sound field characteristics of different types of defects are analyzed by simulation, which will help to optimize the detection scheme and corresponding imaging method in practice so as to improve the detection quality.展开更多
Downhole acoustic telemetry(DAT),using a long drill string with periodical structures as the channel,is a prospective technology for improving the transmission rate of logging while drilling(LWD)data.Previous studies ...Downhole acoustic telemetry(DAT),using a long drill string with periodical structures as the channel,is a prospective technology for improving the transmission rate of logging while drilling(LWD)data.Previous studies only focused on the acoustic property of a free drill string and neglected the coupling between pipes and fluid-filled boreholes.In addition to the drill-string waves,a series of fluid waves are recorded in the DAT channel,which has not been investigated yet.Unpredictable channel characteristics result in lower transmission rates and stability than expected.Therefore,a more realistic channel model is needed considering the fluid-filled borehole.In this paper,we propose a hybrid modeling method to investigate the response characteristics of the DAT channel.By combining the axial wavenumbers and excitation functions of mode waves in radially layered LWD structures,the channel model is approximated to the 1-D propagation,which considers transmission,reflection,and interconversion of the drillstring and fluid waves.The proposed 1-D approximation has been well validated by comparing the 2-D finite-difference modeling.It is revealed that the transmitted and converted fluid waves interfere with the drill-string wave,which characterizes the DAT channel as a particular coherent multi-path channel.When a fluid-filled borehole surrounds the drill string,the channel responses exhibit considerable delay as well as strong frequency selectivity in amplitude and phase.These new findings suggest that the complexity of the channel response has been underestimated in the past,and therefore channel measurements on the ground are unreliable.To address these channel characteristics,we apply a noncoherent demodulation strategy.The transmission rate for synthetic data reaches 15 bps in a 94.5 m long channel,indicating that the acoustic telemetry is promising to break the low-speed limitation of mud-pulse telemetry.展开更多
Modeling of a drill-string acoustic channel has been an important topic in downhole telemetry for a long time.The propagation of drill-string guided waves in the borehole contains excitation,attenuation,and mode conve...Modeling of a drill-string acoustic channel has been an important topic in downhole telemetry for a long time.The propagation of drill-string guided waves in the borehole contains excitation,attenuation,and mode conversion issues that have not been considered by existing modeling methods.In this article,we formulate a hybrid modeling method to investigate the response characteristics of a fundamental-mode drill-string wave in various borehole environments.This hybrid method provides channel functions,including transmitting and receiving deployments,periodicity of the structure,and formation property changes.The essential physics of the drill-string wave propagation is captured with a one-dimensional model.The analytical solutions of the wavefield in multilayered cylindrical structures are introduced into a propagation matrix to express drill-string-wave interactions with the borehole environments.The effectiveness of the proposed method is confirmed through comparison with the finite-difference method.In addition,by designing numerical models,we investigate the conversion effect of the drill-string wave at the tool joint.We demonstrate that the conversion intensity of the drill-string wave is positively correlated not only with the cross-sectional area of the tool joint but also with the wave impedance of the outer formation.Hard formation outside the borehole reduces the energy leakage while intensifying the conversion of drill-string waves to Stoneley waves,and the opposite is true for the drill string in an infinite fluid.The converted Stoneley waves interfere with the drill-string waves,resulting in variations of bandgap distribution,which challenges the reliability of the data transmission.展开更多
An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments.The internal waves are numerically produced by tidal forcing over a continental slope using an ...An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments.The internal waves are numerically produced by tidal forcing over a continental slope using an ocean model.Three parameters(i.e.,internal wave,source depth,and water depth)contribute to the dynamic waveguide environments,and result in stochastic sound fields.The sensitivity of the transmission loss(TL)to environment parameters,statistical characteristics of the TL variation,and the associated physical mechanisms are investigated by the Sobol sensitivity analysis method,the Monte Carlo sampling,and the coupled normal mode theory,respectively.The results show that the TL is most sensitive to the source depth in the near field,resulted from the initial amplitudes of higher-order modes;while in middle and far fields,the internal waves are responsible for more than 80%of the total acoustic propagation contribution.In addition,the standard deviation of the TL in the near field and the shallow layer is smaller than those in the middle and far fields and the deep layer.展开更多
Western Subarctic Gyre(WSG),which possesses distinctive differences in oceanographic and biogeochemical processes,is situated in the northwest subarctic Pacific.The WSG is characterized by high nutrient and low chloro...Western Subarctic Gyre(WSG),which possesses distinctive differences in oceanographic and biogeochemical processes,is situated in the northwest subarctic Pacific.The WSG is characterized by high nutrient and low chlorophyll.We carried out a field investigation in this area in summer 2020 and performed microscopic observation,cytometric counting,and RuBisCO large subunit(rbc L)gene analysis to understand the community structure and spatial distribution of chromophytic phytoplankton better.Microscopic method revealed that total phytoplankton(>10μm,including Bacillariophyta,Dinoflagellata,Ochrophyta,and Chlorophyta)abundances ranged(0.6×10^(3))-(167.4×10^(3))cells/L with an increasing trend from south to north.Dinoflagellates and Pennatae diatoms dominated the phytoplankton assemblages in the southern and northern stations,respectively.Major chromophytic phytoplankton groups derived from rbc L genes included Haptophyta,Ochrophyta,Bacillariophyta,as well as rarely occurring groups,such as Xanthophyta,Cyanobacteria,Dinoflagellata,Rhodophyta,and Cryptophyta.At the phylum level,Haptophyta was the most abundant phylum,accounting for approximately 30.80%of the total obtained operational taxonomic units in all samples.Ochrophyta and Bacillariophyta were the second and third most abundant phylum,and their relative abundance was 20.26% and 19.60%,respectively.Further,redundancy analysis showed that high proportion of diatoms(e.g.,microscopic and rbc L methods)was positively correlated with nutrients(e.g.,dissolved inorganic nitrogen(DIN),dissolved inorganic phosphorous,and dissolved silicate(DSi))and negatively correlated with temperature and salinity.The proportion of Ochrophyta,Rhodophyta,and Cyanobateria identified by rbc L genes was positively correlated with salinity and temperature and showed negative correlation to nutrients.This work is the first molecular study of phytoplankton accomplished in the WSG,and our results show some discrepancies between morphological observation and rbc L gene sequences,which highlight the necessity of combining the microscopic and molecular methods to reveal the diversity of phytoplankton in marine environment.展开更多
The acoustic properties of seafloor sediment are essential parameters in the exploration of marine resources,ocean scientific research and ocean engineering.Seafloor sediment samples were collected at the southern U-b...The acoustic properties of seafloor sediment are essential parameters in the exploration of marine resources,ocean scientific research and ocean engineering.Seafloor sediment samples were collected at the southern U-boundary of the South China Sea(SCS),and the acoustic and physical properties were measured in the laboratory.The correlation between physical and sound speed ratio(SSR)was discussed,and SSR-physical property empirical regressions in the Sunda Shelf were established for the first time.Compared with the northern continental shelf of SCS,the Sunda Shelf are mainly silty and sand sediment,and the SSR ranges from 0.9949 to 1.0944,which has higher SSR than the northern continental shelf,implies that the Sunda Shelf is a high SSR area.Since the same kind of sediment has different physical properties,the single physical parameter of sediment cannot fully represent the acoustic properties of sediment,therefore,the multiple parameter prediction model should develop in the future to improve the prediction precision.展开更多
We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluct...We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluctuation was small,meaning that bottom parameters can be well estimated from acoustic signals.We inverted the acoustic parameters of sediment by using a hybrid inversion scheme that combines the matched field processing inversion with Hamilton sediment empirical relationship and transmission loss data.The numerical results show excellent agreement with the experiment data,indicating validity of the inverted parameters.展开更多
Underwater acoustic applications depend critically on the prediction of sound propagation, which can be significantly affected by a rough surface, especially in shallow water. This paper aims to investigate how random...Underwater acoustic applications depend critically on the prediction of sound propagation, which can be significantly affected by a rough surface, especially in shallow water. This paper aims to investigate how randomly fluctuating surface influences transmission loss(TL) in shallow water. The one-dimension wind-wave spectrum, Monterey–Miami parabolic equation(MMPE) model, Monte Carlo method, and parallel computing technology are combined to investigate the effects of different sea states on sound propagation. It is shown that TL distribution properties are related to the wind speed,frequency, range, and sound speed profile. In a homogenous waveguide, with wind speed increasing, the TLs are greater and more dispersive. For a negative thermocline waveguide, when the source is above the thermocline and the receiver is below that, the effects of the rough surface are the same and more significant. When the source and receiver are both below the thermocline, the TL distributions are nearly the same for different wind speeds. The mechanism of the different TL distribution properties in the thermocline environment is explained by using ray theory. In conclusion, the statistical characteristics of TL are affected by the relative roughness of the surface, the interaction strength of the sound field with the surface, and the changes of propagating angle due to refraction.展开更多
A sound speed profile plays an important role in shallow water sound propagation.Concurrent with in-situ measurements,many inversion methods,such as matched-field inversion,have been put forward to invert the sound sp...A sound speed profile plays an important role in shallow water sound propagation.Concurrent with in-situ measurements,many inversion methods,such as matched-field inversion,have been put forward to invert the sound speed profile from acoustic signals.However,the time cost of matched-field inversion may be very high in replica field calculations.We studied the feasibility and robustness of an acoustic tomography scheme with matched-field processing in shallow water,and described the sound speed profile by empirical orthogonal functions.We analyzed the acoustic signals from a vertical line array in ASIAEX2001 in the East China Sea to invert sound speed profiles with estimated empirical orthogonal functions and a parallel genetic algorithm to speed up the inversion.The results show that the inverted sound speed profiles are in good agreement with conductivity-temperature-depth measurements.Moreover,a posteriori probability analysis is carried out to verify the inversion results.展开更多
Using deep convolutional neural networks as primary learners and a deep neural network as meta-learner, source ranging is solved as a regression problem with the ensemble learning method. Simulated acoustic data from ...Using deep convolutional neural networks as primary learners and a deep neural network as meta-learner, source ranging is solved as a regression problem with the ensemble learning method. Simulated acoustic data from the acoustic propagation model are used as the training data. Real data from an experiment in the South China Sea are used as the test data to demonstrate the performance. The results indicate that in the direct zone of deep water, signals received by a very deep receiver can be used to estimate the range of underwater sound source.Within 30 km, the mean absolute error of the range predictions is 1.0 km and the mean absolute percentage error is 7.9%.展开更多
A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by hig...A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by high-intensity ultrasonic pulses. In the finite element model, the high-power ultrasonic transducer is modeled by using a piezoelectric thermal-analogy method, and the dynamical interaction between both crack faces is modeled using a contact-impact theory. In the simulations, the frictional heating taking place at the crack faces is quantitatively calculated by using finite element thermal-structural coupling analysis, especially, the influences of acoustic chaos to plate vibration and crack heating are calculated and analysed in detail. Meanwhile, the related ultrasonic infrared images are also obtained experimentally, and the theoretical simulation results are in agreement with that of the experiments. The results show that, by using the theoretical method, a good simulation of dynamic interaction and friction heating process of the crack faces under non-chaotic or chaotic sound excitation can be obtained.展开更多
基金Project supported by the National Key Research and Development Program of China (Grant No.2020YFA0211400)the State Key Program of the National Natural Science Foundation of China (Grant No.11834008)+3 种基金the National Natural Science Foundation of China (Grant Nos.12174192 and 12204119)the Fund from the State Key Laboratory of Acoustics,Chinese Academy of Sciences (Grant No.SKLA202210)the Fund from the Key Laboratory of Underwater Acoustic Environment,Chinese Academy of Sciences (Grant No.SSHJ-KFKT-1701)the Science and Technology Foundation of Guizhou Province,China (Grant No.ZK[2023]249)。
文摘Acoustic radiation force(ARF), as an important particle manipulation method, has been extensively studied in recent years. With the introduction of the concept of “acoustic tweezers”, negative acoustic radiation has become a research hotspot. In this paper, a scheme of realizing negative ARF based on the multiple-layered spherical structure design is proposed. The specific structure and design idea are presented. Detailed theoretical calculation analysis is carried out.Numerical simulations have been performed to verify the correctness of this prediction. The conjecture that the suppression of backscattering can achieve negative ARF is verified concretely, which greatly expands the application prospect and design ideas of the ARF. This work has laid a theoretical foundation for realizing precise control of the structure.
基金Project supported by the Natural Science Foundation of Jilin Province of China(Grant Nos.20240402081GH and 20220101012JC)the National Natural Science Foundation of China(Grant No.42074139)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant No.SKLA202308)。
文摘Thickness measurement plays an important role in the monitoring of pipeline corrosion damage. However, the requirement for prior knowledge of the shear wave velocity in the pipeline material for popular ultrasonic thickness measurement limits its widespread application. This paper proposes a method that utilizes cylindrical shear horizontal(SH) guided waves to estimate pipeline thickness without prior knowledge of shear wave velocity. The inversion formulas are derived from the dispersion of higher-order modes with the high-frequency approximation. The waveform of the example problems is simulated using the real-axis integral method. The data points on the dispersion curves are processed in the frequency domain using the wave-number method. These extracted data are then substituted into the derived formulas. The results verify that employing higher-order SH guided waves for the evaluation of thickness and shear wave velocity yields less than1% error. This method can be applied to both metallic and non-metallic pipelines, thus opening new possibilities for health monitoring of pipeline structures.
基金funded by the Excellent Youth Science Fund of Heilongjiang Province(Grant No.YQ2022F001).
文摘The estimation of sparse underwater acoustic(UWA)channels can be regarded as an inference problem involving hidden variables within the Bayesian framework.While the classical sparse Bayesian learning(SBL),derived through the expectation maximization(EM)algorithm,has been widely employed for UWA channel estimation,it still differs from the real posterior expectation of channels.In this paper,we propose an approach that combines variational inference(VI)and Markov chain Monte Carlo(MCMC)methods to provide a more accurate posterior estimation.Specifically,the SBL is first re-derived with VI,allowing us to replace the posterior distribution of the hidden variables with a variational distribution.Then,we determine the full conditional probability distribution for each variable in the variational distribution and then iteratively perform random Gibbs sampling in MCMC to converge the Markov chain.The results of simulation and experiment indicate that our estimation method achieves lower mean square error and bit error rate compared to the classic SBL approach.Additionally,it demonstrates an acceptable convergence speed.
文摘The 9th International Symposium on Modern Acoustics was held in Nanjing,China,on May 19 -22,2012,which has been introduced in an article published in Journal of Nanjing University (Natural Sciences),2012[1].As described previously,after peer reviewing,a part of the original papers were selected to be published in Journal of Nanjing University(Natural Sciences),which were separated as two issues:the first has already been published in a special issue of the journal in 2012[2~19].
基金Project supported by the National Key Research and Development program of China(Grant No.2020YFA0211400)the State Key Program of the National Natural Science of China(Grant No.11834008)+2 种基金the National Natural Science Foundation of China(Grant No.12174192)the Fund fromthe State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant No.SKLA202008)the Fund from the Key Laboratory of Underwater Acoustic Environment,Chinese Academy of Sciences(Grant No.SSHJ-KFKT-1701)。
文摘Nonlinear phononic crystals have attracted great interest because of their unique properties absent in linear phononic crystals.However,few researches have considered the bilinear nonlinearity as well as its consequences in acoustic metamaterials.Hence,we introduce bilinear nonlinearity into acoustic metamaterials,and investigate the propagation behaviors of the fundamental and the second harmonic waves in the nonlinear acoustic metamaterials by discretization method,revealing the influence of the system parameters.Furthermore,we investigate the influence of partially periodic nonlinear acoustic metamaterials on the second harmonic wave propagation,and the results suggest that pass-band and band-gap can be transformed into each other under certain conditions.Our findings could be beneficial to the band gap control in nonlinear acoustic metamaterials.
基金This work is supported by the National Natural Science Founda-tion of China(Grant No.11874280)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant No.SKLA202211).
文摘Acoustic tweezing cytometry(ATC)is a recently developed method for cell mechanics regulation.Tar-geted microbubbles,which are attached to integrins and subsequently the actin cytoskeleton,anchor,amplify and transmit the mechanical energy in an acoustic field inside the cells,eliciting prominent cy-toskeleton contractile force increases in various cell types.We propose that a mechanochemical con-version mechanism is critical for the high efficiency of ATC to activate cell contractility responses.Our models predict key experimental observations.Moreover,we study the influences of ATC parameters(ul-trasound center frequency,pulse repetition frequency,duty cycle,and acoustic pressure),cell areas,the number of ATC stimuli,and extracellular matrix rigidity on cell contractility responses to ATC.The simu-lation results suggest that it is large molecules,rather than small ions,that facilitate global responses to the local ATC stimulation,and the incorporation of visible stress fiber bundles improves the accuracy of modeling.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12174159,12274183,and 51976079)the National Key Research and Development Program of China (Grant No.2020YFC1512403)the Research Project of State Key Laboratory of Mechanical System and Vibration (Grant No.MSV202201)。
文摘The numerical simulations and experimental results of an ultra-broadband acoustic ventilation barrier composed of periodic unit cells are reported in this paper.Based on multiple mechanisms,including sound absorption by eigenmodes of the unit cell and sound reflection by a plate structure on upper surface of the unit cell,a single-layer ventilation barrier with broadband sound reduction is designed,and its working bandwidth can reach about 1560 Hz.The experimental results accord well with the simulation results.Furthermore,two types of three-layer ventilation barriers are designed and demonstrated by using the unit cells with different values of a(the length of the hollow square region)and w(the width of the channel between the adjacent cavities),and the bandwidths of both ventilation barriers can increase to 3160 Hz and 3230 Hz,respectively.The designed barrier structures have the advantages of ultra-broadband sound reduction and ventilation,which paves the way to designing high-performance ventilation barriers for the applications in environmental protection and architectural acoustics.
基金The Natural Science Foundation of Shandong Province of China under contract Nos ZR2022MA051 and ZR2020MA090the Fund of China Postdoctoral Science Foundation under contract No.2020M670891+1 种基金the Shandong University of Science and Technology Research Fund under contract No.2019TDJH103the Talent Introduction Plan for Youth Innovation Team in Universities of Shandong Province(Innovation Team of Satellite Positioning and Navigation).
文摘The shallow-water temperature profile is typically parameterized using a few empirical orthogonal function(EOF)coefficients.However,when the experimental area is poorly known or highly variable,the adaptability of the EOFs will be significantly reduced.In this study,a new set of basis functions,generated by combining the internal-wave eigenmodes with the average temperature gradient,is developed for characterizing the temperature perturbations.Temperature profiles recorded by a thermistor chain in the South China Sea in 2015 are processed and analyzed.Compared to the EOFs,the new set of basis functions has higher reconstruction accuracy and adaptability;it is also more stable in ocean regions that have internal waves.
基金Project supported by the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. ZDBS-LY-7023)。
文摘The problem of three-dimensional(3D) acoustic scattering in a complex medium has aroused considerable interest of researchers for many years. An ultrasonic scattered field calculating technique is proposed to study the scattering echo from strongly scattered materials in a two-layer medium in this work. Firstly, with the high frequency stationary phase method,the Green's function of two-layer fluid media is derived. And then based on the idea of integral equation discretization,the Green's function method is extended to two-layer fluid media to derive the scattering field expression of defects in a complex medium. With this method, the scattering field of 3D defect in a two-layer medium is calculated and the characteristics of received echoes are studied. The results show that this method is able to solve the scattering P wave field of 3D defect with arbitrary shape at any scattering intensity in two-layer media. Considering the circumstance of waterimmersion ultrasonic non-destructive test(NDT), the scattering sound field characteristics of different types of defects are analyzed by simulation, which will help to optimize the detection scheme and corresponding imaging method in practice so as to improve the detection quality.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174421 and 11734017)the Scientific Instrument Developing Project of the Chinese Academy of Sciences,China(Grant Nos.YJKYYQ20200072 and GJJSTD20210008).
文摘Downhole acoustic telemetry(DAT),using a long drill string with periodical structures as the channel,is a prospective technology for improving the transmission rate of logging while drilling(LWD)data.Previous studies only focused on the acoustic property of a free drill string and neglected the coupling between pipes and fluid-filled boreholes.In addition to the drill-string waves,a series of fluid waves are recorded in the DAT channel,which has not been investigated yet.Unpredictable channel characteristics result in lower transmission rates and stability than expected.Therefore,a more realistic channel model is needed considering the fluid-filled borehole.In this paper,we propose a hybrid modeling method to investigate the response characteristics of the DAT channel.By combining the axial wavenumbers and excitation functions of mode waves in radially layered LWD structures,the channel model is approximated to the 1-D propagation,which considers transmission,reflection,and interconversion of the drillstring and fluid waves.The proposed 1-D approximation has been well validated by comparing the 2-D finite-difference modeling.It is revealed that the transmitted and converted fluid waves interfere with the drill-string wave,which characterizes the DAT channel as a particular coherent multi-path channel.When a fluid-filled borehole surrounds the drill string,the channel responses exhibit considerable delay as well as strong frequency selectivity in amplitude and phase.These new findings suggest that the complexity of the channel response has been underestimated in the past,and therefore channel measurements on the ground are unreliable.To address these channel characteristics,we apply a noncoherent demodulation strategy.The transmission rate for synthetic data reaches 15 bps in a 94.5 m long channel,indicating that the acoustic telemetry is promising to break the low-speed limitation of mud-pulse telemetry.
基金the National Natural Science Foundation of China(Grant Nos.11734017 and 12174421)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant Nos.YJKYYQ20200072 and GJJSTD20210008).
文摘Modeling of a drill-string acoustic channel has been an important topic in downhole telemetry for a long time.The propagation of drill-string guided waves in the borehole contains excitation,attenuation,and mode conversion issues that have not been considered by existing modeling methods.In this article,we formulate a hybrid modeling method to investigate the response characteristics of a fundamental-mode drill-string wave in various borehole environments.This hybrid method provides channel functions,including transmitting and receiving deployments,periodicity of the structure,and formation property changes.The essential physics of the drill-string wave propagation is captured with a one-dimensional model.The analytical solutions of the wavefield in multilayered cylindrical structures are introduced into a propagation matrix to express drill-string-wave interactions with the borehole environments.The effectiveness of the proposed method is confirmed through comparison with the finite-difference method.In addition,by designing numerical models,we investigate the conversion effect of the drill-string wave at the tool joint.We demonstrate that the conversion intensity of the drill-string wave is positively correlated not only with the cross-sectional area of the tool joint but also with the wave impedance of the outer formation.Hard formation outside the borehole reduces the energy leakage while intensifying the conversion of drill-string waves to Stoneley waves,and the opposite is true for the drill string in an infinite fluid.The converted Stoneley waves interfere with the drill-string waves,resulting in variations of bandgap distribution,which challenges the reliability of the data transmission.
基金the National Key Research and Development Program of China(Grant No.2020YFA0607900)the National Natural Science Foundation of China(Grant Nos.42176019 and 11874061)the Youth Innovation Promotion Association CAS(Grant No.2021023).
文摘An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments.The internal waves are numerically produced by tidal forcing over a continental slope using an ocean model.Three parameters(i.e.,internal wave,source depth,and water depth)contribute to the dynamic waveguide environments,and result in stochastic sound fields.The sensitivity of the transmission loss(TL)to environment parameters,statistical characteristics of the TL variation,and the associated physical mechanisms are investigated by the Sobol sensitivity analysis method,the Monte Carlo sampling,and the coupled normal mode theory,respectively.The results show that the TL is most sensitive to the source depth in the near field,resulted from the initial amplitudes of higher-order modes;while in middle and far fields,the internal waves are responsible for more than 80%of the total acoustic propagation contribution.In addition,the standard deviation of the TL in the near field and the shallow layer is smaller than those in the middle and far fields and the deep layer.
基金Supported by the National Key Research and Development Program of China(No.2019YFD0901401)the National Natural Science Foundation of China(Nos.42176206,81900630)+2 种基金the Natural Science Foundation of Shandong Province(No.ZR2021MD071)the“One Hundred Talents”Project of Guangxi(No.6020303891251)the Outstanding Youth Project of Yunnan Provincial Department of Science and Technology(No.2019F1019)。
文摘Western Subarctic Gyre(WSG),which possesses distinctive differences in oceanographic and biogeochemical processes,is situated in the northwest subarctic Pacific.The WSG is characterized by high nutrient and low chlorophyll.We carried out a field investigation in this area in summer 2020 and performed microscopic observation,cytometric counting,and RuBisCO large subunit(rbc L)gene analysis to understand the community structure and spatial distribution of chromophytic phytoplankton better.Microscopic method revealed that total phytoplankton(>10μm,including Bacillariophyta,Dinoflagellata,Ochrophyta,and Chlorophyta)abundances ranged(0.6×10^(3))-(167.4×10^(3))cells/L with an increasing trend from south to north.Dinoflagellates and Pennatae diatoms dominated the phytoplankton assemblages in the southern and northern stations,respectively.Major chromophytic phytoplankton groups derived from rbc L genes included Haptophyta,Ochrophyta,Bacillariophyta,as well as rarely occurring groups,such as Xanthophyta,Cyanobacteria,Dinoflagellata,Rhodophyta,and Cryptophyta.At the phylum level,Haptophyta was the most abundant phylum,accounting for approximately 30.80%of the total obtained operational taxonomic units in all samples.Ochrophyta and Bacillariophyta were the second and third most abundant phylum,and their relative abundance was 20.26% and 19.60%,respectively.Further,redundancy analysis showed that high proportion of diatoms(e.g.,microscopic and rbc L methods)was positively correlated with nutrients(e.g.,dissolved inorganic nitrogen(DIN),dissolved inorganic phosphorous,and dissolved silicate(DSi))and negatively correlated with temperature and salinity.The proportion of Ochrophyta,Rhodophyta,and Cyanobateria identified by rbc L genes was positively correlated with salinity and temperature and showed negative correlation to nutrients.This work is the first molecular study of phytoplankton accomplished in the WSG,and our results show some discrepancies between morphological observation and rbc L gene sequences,which highlight the necessity of combining the microscopic and molecular methods to reveal the diversity of phytoplankton in marine environment.
基金Supported by the Guangdong Special Support Key Team Program(No.2019BT02H594)the National Key R&D Program of China(No.2021YFF0501202)+5 种基金the Youth Innovation Promotion Association CASthe National Natural Science Foundation of China(Nos.41706045,42176191,41773039,U22A2012)the Rising Star Foundation of the Integrated Research Center for Islands and Reefs Sciences,CAS(No.ZDRW-XH-2021-2-03)the CAS Key Laboratory of Science and Technology on Operational Oceanography Open Project Funding(No.OOST2021-01)the Guangdong Natural Science Foundation(No.2017A030313237)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Nos.SKLA202007,SKLA202106)。
文摘The acoustic properties of seafloor sediment are essential parameters in the exploration of marine resources,ocean scientific research and ocean engineering.Seafloor sediment samples were collected at the southern U-boundary of the South China Sea(SCS),and the acoustic and physical properties were measured in the laboratory.The correlation between physical and sound speed ratio(SSR)was discussed,and SSR-physical property empirical regressions in the Sunda Shelf were established for the first time.Compared with the northern continental shelf of SCS,the Sunda Shelf are mainly silty and sand sediment,and the SSR ranges from 0.9949 to 1.0944,which has higher SSR than the northern continental shelf,implies that the Sunda Shelf is a high SSR area.Since the same kind of sediment has different physical properties,the single physical parameter of sediment cannot fully represent the acoustic properties of sediment,therefore,the multiple parameter prediction model should develop in the future to improve the prediction precision.
基金This work was supported by grants fromthe National Natural Science Foundation of China(No.30470564,30670695)an international joint grantfromthe NSFC+1 种基金the Russian Foundation of Basic Research(NSFC:No.30611120056RFBR:No.05-04-39008)
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-02)the National Natural Science Foundation of China (Nos.10974218 and 10734100)
文摘We performed a long range acoustic propagation experiment in the South China Sea(SCS) in November 2004.The environment of the experiment was with an isothermal sound speed profile,where influence of water volume fluctuation was small,meaning that bottom parameters can be well estimated from acoustic signals.We inverted the acoustic parameters of sediment by using a hybrid inversion scheme that combines the matched field processing inversion with Hamilton sediment empirical relationship and transmission loss data.The numerical results show excellent agreement with the experiment data,indicating validity of the inverted parameters.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11434012,11874061,and 41561144006)
文摘Underwater acoustic applications depend critically on the prediction of sound propagation, which can be significantly affected by a rough surface, especially in shallow water. This paper aims to investigate how randomly fluctuating surface influences transmission loss(TL) in shallow water. The one-dimension wind-wave spectrum, Monterey–Miami parabolic equation(MMPE) model, Monte Carlo method, and parallel computing technology are combined to investigate the effects of different sea states on sound propagation. It is shown that TL distribution properties are related to the wind speed,frequency, range, and sound speed profile. In a homogenous waveguide, with wind speed increasing, the TLs are greater and more dispersive. For a negative thermocline waveguide, when the source is above the thermocline and the receiver is below that, the effects of the rough surface are the same and more significant. When the source and receiver are both below the thermocline, the TL distributions are nearly the same for different wind speeds. The mechanism of the different TL distribution properties in the thermocline environment is explained by using ray theory. In conclusion, the statistical characteristics of TL are affected by the relative roughness of the surface, the interaction strength of the sound field with the surface, and the changes of propagating angle due to refraction.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCX1-YW-12-02)the National Natural Science Foundation of China (Nos.10974218,10734100)
文摘A sound speed profile plays an important role in shallow water sound propagation.Concurrent with in-situ measurements,many inversion methods,such as matched-field inversion,have been put forward to invert the sound speed profile from acoustic signals.However,the time cost of matched-field inversion may be very high in replica field calculations.We studied the feasibility and robustness of an acoustic tomography scheme with matched-field processing in shallow water,and described the sound speed profile by empirical orthogonal functions.We analyzed the acoustic signals from a vertical line array in ASIAEX2001 in the East China Sea to invert sound speed profiles with estimated empirical orthogonal functions and a parallel genetic algorithm to speed up the inversion.The results show that the inverted sound speed profiles are in good agreement with conductivity-temperature-depth measurements.Moreover,a posteriori probability analysis is carried out to verify the inversion results.
基金the National Natural Science Foundation of China under Grant Nos 11434012 and 11874061
文摘Using deep convolutional neural networks as primary learners and a deep neural network as meta-learner, source ranging is solved as a regression problem with the ensemble learning method. Simulated acoustic data from the acoustic propagation model are used as the training data. Real data from an experiment in the South China Sea are used as the test data to demonstrate the performance. The results indicate that in the direct zone of deep water, signals received by a very deep receiver can be used to estimate the range of underwater sound source.Within 30 km, the mean absolute error of the range predictions is 1.0 km and the mean absolute percentage error is 7.9%.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10574073)
文摘A three-dimensional thermo-mechanical coupled finite element model is built up to simulate the phenomena of dynamical contact and frictional heating of crack faces when the plate containing the crack is excited by high-intensity ultrasonic pulses. In the finite element model, the high-power ultrasonic transducer is modeled by using a piezoelectric thermal-analogy method, and the dynamical interaction between both crack faces is modeled using a contact-impact theory. In the simulations, the frictional heating taking place at the crack faces is quantitatively calculated by using finite element thermal-structural coupling analysis, especially, the influences of acoustic chaos to plate vibration and crack heating are calculated and analysed in detail. Meanwhile, the related ultrasonic infrared images are also obtained experimentally, and the theoretical simulation results are in agreement with that of the experiments. The results show that, by using the theoretical method, a good simulation of dynamic interaction and friction heating process of the crack faces under non-chaotic or chaotic sound excitation can be obtained.