We investigate the null tests of cosmic accelerated expansion by using the baryon acoustic oscillation(BAO)data measured by the dark energy spectroscopic instrument(DESI)and reconstruct the dimensionless Hubble parame...We investigate the null tests of cosmic accelerated expansion by using the baryon acoustic oscillation(BAO)data measured by the dark energy spectroscopic instrument(DESI)and reconstruct the dimensionless Hubble parameter E(z)from the DESI BAO Alcock-Paczynski(AP)data using Gaussian process to perform the null test.We find strong evidence of accelerated expansion from the DESI BAO AP data.By reconstructing the deceleration parameter q(z) from the DESI BAO AP data,we find that accelerated expansion persisted until z■0.7 with a 99.7%confidence level.Additionally,to provide insights into the Hubble tension problem,we propose combining the reconstructed E(z) with D_(H)/r_(d) data to derive a model-independent result r_(d)h=99.8±3.1 Mpc.This result is consistent with measurements from cosmic microwave background(CMB)anisotropies using the ΛCDM model.We also propose a model-independent method for reconstructing the comoving angular diameter distance D_(M)(z) from the distance modulus μ,using SNe Ia data and combining this result with DESI BAO data of D_(M)/r_(d) to constrain the value of r_(d).We find that the value of r_(d),derived from this model-independent method,is smaller than that obtained from CMB measurements,with a significant discrepancy of at least 4.17σ.All the conclusions drawn in this paper are independent of cosmological models and gravitational theories.展开更多
In recent years,acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing.For practical implementation,these logic gates must ...In recent years,acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing.For practical implementation,these logic gates must operate over a certain bandwidth to ensure reliable performance.However,current experimental realizations have predominantly been confined to single-frequency or narrowband operation,leaving their broadband capabilities largely unverified.To address this gap,we present both numerical and experimental demonstrations of three basic acoustic logic gates(OR,NOT,and AND)using a phased unit cell composed of a central channel flanked by two arrays of semicircular cavities.By leveraging phase modulation of the unit cells and linear interference of sound,we achieve these logic operations with a uniform threshold of I_(t)=0.25.Remarkably,the measured fractional bandwidths(bandwidth relative to center frequency)reach approximately 111.5%(OR),37.2%(NOT),and 48.5%(AND),demonstrating ultra-broadband functionality.The proposed logic gates combine exceptional bandwidth with structural simplicity,offering significant potential for applications in acoustic computing,information processing,and integrated acoustic systems.展开更多
We predict high-velocity magnetic domain wall(DW)motion driven by out-of-plane acoustic spin in surface acoustic waves(SAWs).We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128...We predict high-velocity magnetic domain wall(DW)motion driven by out-of-plane acoustic spin in surface acoustic waves(SAWs).We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128∘Y-LiNbO_(3) substrate exhibits uniform out-of-plane spin angular momentum.This acoustic spin triggers the DW motion at a velocity exceeding 50 m/s in a way that is similar to the spin-transfer-torque effect.This phenomenon highlights the potential of acoustic spin in enabling rapid DW displacement,offering an innovative approach to developing energy-efficient spintronic devices.展开更多
Decorative construction typically accounts for 20–50%of total project costs.China introduces energy-saving panels,primarily composed of sand particles,to reduce its energy consumption.Most importantly,it has the abil...Decorative construction typically accounts for 20–50%of total project costs.China introduces energy-saving panels,primarily composed of sand particles,to reduce its energy consumption.Most importantly,it has the ability to efficiently resolve intricate acoustic issues with remarkable speed and convenience.This study focuses on sand-based energy-saving panels,which efficiently address complex acoustic issues while reducing energy consumption.Using Delany-Bazley empirical models and acoustic simulation software(Zorba,INSUL),four surface treatments(Plain-P,SA1,PF,SA2)were compared to optimize room acoustics.Results show that plain sand spray(Plain-P)exhibits the highest sound absorption capacity,with a noise reduction coefficient(NRC)of 0.85 and a sound absorption coefficient exceeding 0.9 in high frequencies.Simulation of rooms with sand-based wall coatings confirms its environmental friendliness and adaptability to curved surfaces,arched ceilings,and special-shaped walls.The results demonstrate that empirical models and simulation together improve the approach to studying acoustic parameters like sound absorption through sound impedance and propagation coefficient.Additionally,the material expresses excellent sound insulation,with an average transmission loss(TL)of approximately 70.71 dB.This research highlights the overlooked potential of sand-based materials,providing a practical solution for energy-efficient and acoustically optimized interior design,specifically emphasising a method that has not been paid much attention to.展开更多
Techniques for manipulating nanodroplets lie at the core of numerous miniaturized systems in chemical and biological research endeavors.In this study,we introduce a versatile methodology for calculating the acoustic v...Techniques for manipulating nanodroplets lie at the core of numerous miniaturized systems in chemical and biological research endeavors.In this study,we introduce a versatile methodology for calculating the acoustic vortex field,integrating hybrid wave equation principles with ray acoustics.This approach demonstrates remarkable consistency between simulated results and experimental observations.Importantly,both theoretical analysis and experimental validation confirm that particles whose diameters match the wavelength(Mie particles)can be effectively trapped within a focused acoustic vortex field,rotating in circular trajectories centered at the vortex center.This research significantly expands the scope of acoustic vortex manipulation for larger particles and introduces a novel implementation strategy with potential applications in targeted drug delivery for clinical adjuvant therapy.展开更多
1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to und...1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to undesirable consequences such as structural damage and performance deterioration.The challenge lies in predicting and mitigating these instabilities due to the complex interplay of various physical phenomena like acoustic propagation,turbulent flow,and combustion chemistry,which are summarized in detail in Aimee S.Morgans and Dong Yang's published article.展开更多
Ultrasound neuromodulation is a powerful tool for brain investigation and holds great promise for treating brain diseases.However,due to the heterogeneous acoustic properties of skulls,existing ultrasound neuromodulat...Ultrasound neuromodulation is a powerful tool for brain investigation and holds great promise for treating brain diseases.However,due to the heterogeneous acoustic properties of skulls,existing ultrasound neuromodulation faces the challenge of severe transcranial acoustic attenuation.To overcome such limitations,we report an implantable bio-chip for visible and controllable mi-crowave-induced transcranial acoustic generation(MI-tAG).The bio-chip is soft,flexible,and biocompatible,with a thickness of 3mm,making it suitable for human intracranial implantation.The constituted fluid channels can cover an area of 50 mm×60 mm,enabling widefield neuronstimulation.The particles filled in the fluid channels have both high microwave absorption.ensuring efficient ultrasound generation,and magnetism,allowing noncontact and flexible ma-nipulation by external magnetic fields.The experimental results demonstrate that the optimal MI-tAG can be realized by the combination of particles arranged in a linear pattern and corre-sponding illumination via a linearly polarized microwave.Stability evaluation indicates that the particles can maintain a consistent acoustic intensity without degradation for at least seven days.The results of in vitro and in vivo experiments show that the MII-tAG can manipulate ultrasound sources and visibly locate them in real time.This study provides a potential innovative approach for future ultrasound neuromodulation,inspiring the development of more useful methods to advance brain research.This study introduces a promising innovative approach for transcranial acoustic generation,potentially inspiring the development of more effective methods for ad-vancing ultrasound neuromodulation.展开更多
This study explores a sensitivity analysis method based on the boundary element method(BEM)to address the computational complexity in acoustic analysis with ground reflection problems.The advantages of BEM in acoustic...This study explores a sensitivity analysis method based on the boundary element method(BEM)to address the computational complexity in acoustic analysis with ground reflection problems.The advantages of BEM in acoustic simulations and its high computational cost in broadband problems are examined.To improve efficiency,a Taylor series expansion is applied to decouple frequency-dependent terms in BEM.Additionally,the SecondOrder Arnoldi(SOAR)model order reduction method is integrated to reduce computational costs and enhance numerical stability.Furthermore,an isogeometric sensitivity boundary integral equation is formulated using the direct differentiation method,incorporating Cauchy principal value integrals and Hadamard finite part integrals to handle singularities.The proposed method improves the computational efficiency,and the acoustic sensitivity analysis provides theoretical support for further acoustic structure optimization.展开更多
[Objective] The aim was to study the effects of different acoustic frequency of insect sound （IS） and insect-music mixed sound （MS） treatment on the growth of 6 kinds of vegetables.[Method] The insect acoustic gro...[Objective] The aim was to study the effects of different acoustic frequency of insect sound （IS） and insect-music mixed sound （MS） treatment on the growth of 6 kinds of vegetables.[Method] The insect acoustic group,insect-music mixed group and normal control group were designed to determine the related indices of 6 kinds of vegetables in unified management regularly.[Result] After different acoustic frequency treatment,besides soybean plant height,dry root weight of cabbage and greengrocery,there was significant difference of plant height,fresh weight and dry weight between the other vegetables and control.Under acoustic frequency treatment,the growth situations of six kinds of vegetables were better than control.In the growth period,acoustic frequency treatment could promote height growth （except soybean） and edible part yield.[Conclusion] Both of IS and MS could promote the plant growth,but their effects had difference.展开更多
A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be use...A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.展开更多
Acoustic orbital angular momentum(OAM)associated with helicoidal wavefront recently attracts rapidly-growing attentions,offering a new degree of freedom for acoustic manipulation.Due to the unique dynamical behavior a...Acoustic orbital angular momentum(OAM)associated with helicoidal wavefront recently attracts rapidly-growing attentions,offering a new degree of freedom for acoustic manipulation.Due to the unique dynamical behavior and inherent mode orthogonality of acoustic OAM,its harnessing is of fundamental interests for wave physics,with great potential in a plethora of applications.The recent advance in materials physics further boosts efforts into controlling OAM-carrying acoustic vortices,especially acoustic metasurfaces with planar profile and subwavelength thickness.Thanks to their un-conventional acoustic properties beyond attainable in the nature,acoustic artificial structures provide a powerful platform for new research paradigm for efficient generation and diverse manipulation of OAM in ways not possible before,enabling novel applications in diverse scenarios ranging from underwater communication to object manipulation.In this article,we present a comprehensive view of this emerging field by delineating the fundamental physics of OAM-metasurface interac-tion and recent advances in the generation,manipulation,and application of acoustic OAM based on artificial structures,followed by an outlook for promising future directions and potential practical applications.展开更多
In the process of deep engineering excavation,the mechanical properties of rock are significantly influenced by the coupled effects of water and high stress,which greatly increase construction difficulty.To more accur...In the process of deep engineering excavation,the mechanical properties of rock are significantly influenced by the coupled effects of water and high stress,which greatly increase construction difficulty.To more accurately investigate the impact of water disturbance on the failure process of dry rock under high stress and the failure mechanisms of saturated rock in underwater environments,a water environment test chamber and a prefabricated borehole specimen through-water device were designed.A series of experiments were conducted,including uniaxial tests,water-disturbed granite cylinder tests,and through-water disturbance tests on prefabricated hole square specimens.The results showed that the acoustic emission(AE)hits and accumulated energy after the through-water disturbance at the same time were 8.77 and 12.08 times higher than before the disturbance,respectively.And water disturbance increased the proportion of tensile failure and reduced the proportion of shear failure.A key observation was that AE events were mainly generated in the permeation areas near the borehole.The main reason was that under high stress,the weakening effect of water led to the failure of the local mineral structure of the rock,promoting crack extension and triggering overall instability.Notably,failure of the saturated specimens underwater was only observed when the applied load approached the saturation strength of the prefabricated hole square specimens.The study results provide an important theoretical basis for understanding the damage mechanism of water-disturbed rocks in deep engineering,and have significant implications for the design and construction of engineering.展开更多
The loaded rock experiences multiple stages of deformation.It starts with the formation of microcracks at low stresses(crack initiation,CI)and then transitions into unstable crack propagation(crack damage,CD)near the ...The loaded rock experiences multiple stages of deformation.It starts with the formation of microcracks at low stresses(crack initiation,CI)and then transitions into unstable crack propagation(crack damage,CD)near the ultimate strength.In this study,both the acoustic emission method(AEM)and the ultrasonic testing method(UTM)were used to examine the characteristics of AE parameters(b-value,peak frequency,frequency-band energy ratio,and fractal dimension)and ultrasonic(ULT)properties(velocity,amplitude,energy attenuation,and scattering attenuation)of bedded shale at CI,CD,and ultimate strength.The comparison involved analyzing the strain-based method(SBM),AEM,and UTM to determine the thresholds for damage stress.A fuzzy comprehensive evaluation model(FCEM)was created to describe the damage thresholds and hazard assessment.The results indicate that the optimal AE and ULT parameters for identifying CI and CD stress are ringing count,ultrasonic amplitude,energy attenuation,and scattering attenuation of the S-wave.Besides,damage thresholds were detected earlier by AE monitoring,ranging from 3 MPa to 10 MPa.CI and CD identified by UTM occurred later than SBM and AEM,and were in the range of 12 MPa.The b-value,peak frequency,energy ratio in the low-frequency band(0e62.5 kHz),correlation dimension,and sandbox dimension showed low values at the peak stress,while the energy ratio in a moderate-frequency band(187.5e281.25 kHz)and amplitude showed high values.The successful application of FCEM to laboratory testing of shales has demonstrated its ability to quantitatively identify AE/ULT precursors of seismic hazards associated with rock failure.展开更多
The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-...The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.展开更多
The effects of the temperature,salinity,and fluid type on the acoustic characteristics of turbulent flow around a circular cylinder were numerically investigated for the Reynolds numbers of 2.25×10^(4),4.5×1...The effects of the temperature,salinity,and fluid type on the acoustic characteristics of turbulent flow around a circular cylinder were numerically investigated for the Reynolds numbers of 2.25×10^(4),4.5×10^(4),and 9.0×10^(4).Various hybrid methodsReynolds-averaged Navier-Stokes(BANS)with the Ffowcs Williams and Hawkings(FWH)model,detached-eddy simulation(DES)with FWH,and large-eddy simulation with FWH-were used for the acoustic analyses,and their performances were evaluated by comparing the predicted results with the experimental data.The DES-FWH hybrid method was found to be suitable for the aero-and hydro-acoustic analysis.The hydro-acoustic measurements were performed in a silent circulation channel for the Reynolds number of 2.25×10^(4).The results showed that the fluid temperature caused an increase in the overall sound pressure levels(OASPLs)and the maximum sound pressure levels(SPL_(T))for the air medium;however,it caused a decrease for the water medium.The salinity had smaller effects on the OASPL and SPLT compared to the temperature.Moreover,the main peak frequency increased with the air temperature but decreased with the water temperature,and it was nearly constant with the change in the salinity ratio.The SPLT and OASPL for the water medium were quite higher than those for the air medium.展开更多
基金supported in part by the National Key Research and Development Program of China (Grant No.2020YFC2201504)the National Natural Science Foundation of China (Grant Nos.12588101 and 12535002)。
文摘We investigate the null tests of cosmic accelerated expansion by using the baryon acoustic oscillation(BAO)data measured by the dark energy spectroscopic instrument(DESI)and reconstruct the dimensionless Hubble parameter E(z)from the DESI BAO Alcock-Paczynski(AP)data using Gaussian process to perform the null test.We find strong evidence of accelerated expansion from the DESI BAO AP data.By reconstructing the deceleration parameter q(z) from the DESI BAO AP data,we find that accelerated expansion persisted until z■0.7 with a 99.7%confidence level.Additionally,to provide insights into the Hubble tension problem,we propose combining the reconstructed E(z) with D_(H)/r_(d) data to derive a model-independent result r_(d)h=99.8±3.1 Mpc.This result is consistent with measurements from cosmic microwave background(CMB)anisotropies using the ΛCDM model.We also propose a model-independent method for reconstructing the comoving angular diameter distance D_(M)(z) from the distance modulus μ,using SNe Ia data and combining this result with DESI BAO data of D_(M)/r_(d) to constrain the value of r_(d).We find that the value of r_(d),derived from this model-independent method,is smaller than that obtained from CMB measurements,with a significant discrepancy of at least 4.17σ.All the conclusions drawn in this paper are independent of cosmological models and gravitational theories.
基金Project supported by the National Natural Science Foundation of China(Grant No.12174159)。
文摘In recent years,acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing.For practical implementation,these logic gates must operate over a certain bandwidth to ensure reliable performance.However,current experimental realizations have predominantly been confined to single-frequency or narrowband operation,leaving their broadband capabilities largely unverified.To address this gap,we present both numerical and experimental demonstrations of three basic acoustic logic gates(OR,NOT,and AND)using a phased unit cell composed of a central channel flanked by two arrays of semicircular cavities.By leveraging phase modulation of the unit cells and linear interference of sound,we achieve these logic operations with a uniform threshold of I_(t)=0.25.Remarkably,the measured fractional bandwidths(bandwidth relative to center frequency)reach approximately 111.5%(OR),37.2%(NOT),and 48.5%(AND),demonstrating ultra-broadband functionality.The proposed logic gates combine exceptional bandwidth with structural simplicity,offering significant potential for applications in acoustic computing,information processing,and integrated acoustic systems.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0103300)the open research fund of Songshan Lake Materials Laboratory(Grant No.2023SLABFN26)the Natural Science Foundation of Hubei Province(Grant No.2022CFA088)。
文摘We predict high-velocity magnetic domain wall(DW)motion driven by out-of-plane acoustic spin in surface acoustic waves(SAWs).We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128∘Y-LiNbO_(3) substrate exhibits uniform out-of-plane spin angular momentum.This acoustic spin triggers the DW motion at a velocity exceeding 50 m/s in a way that is similar to the spin-transfer-torque effect.This phenomenon highlights the potential of acoustic spin in enabling rapid DW displacement,offering an innovative approach to developing energy-efficient spintronic devices.
基金supported by China Scholarship Counsil(CSC)(grant number:202206935003)Shanxi Province Nature and Science(grant number:202203021222098).
文摘Decorative construction typically accounts for 20–50%of total project costs.China introduces energy-saving panels,primarily composed of sand particles,to reduce its energy consumption.Most importantly,it has the ability to efficiently resolve intricate acoustic issues with remarkable speed and convenience.This study focuses on sand-based energy-saving panels,which efficiently address complex acoustic issues while reducing energy consumption.Using Delany-Bazley empirical models and acoustic simulation software(Zorba,INSUL),four surface treatments(Plain-P,SA1,PF,SA2)were compared to optimize room acoustics.Results show that plain sand spray(Plain-P)exhibits the highest sound absorption capacity,with a noise reduction coefficient(NRC)of 0.85 and a sound absorption coefficient exceeding 0.9 in high frequencies.Simulation of rooms with sand-based wall coatings confirms its environmental friendliness and adaptability to curved surfaces,arched ceilings,and special-shaped walls.The results demonstrate that empirical models and simulation together improve the approach to studying acoustic parameters like sound absorption through sound impedance and propagation coefficient.Additionally,the material expresses excellent sound insulation,with an average transmission loss(TL)of approximately 70.71 dB.This research highlights the overlooked potential of sand-based materials,providing a practical solution for energy-efficient and acoustically optimized interior design,specifically emphasising a method that has not been paid much attention to.
基金Project supported by the National Key R&D Program of China(Grant No.2023YFE0201900)。
文摘Techniques for manipulating nanodroplets lie at the core of numerous miniaturized systems in chemical and biological research endeavors.In this study,we introduce a versatile methodology for calculating the acoustic vortex field,integrating hybrid wave equation principles with ray acoustics.This approach demonstrates remarkable consistency between simulated results and experimental observations.Importantly,both theoretical analysis and experimental validation confirm that particles whose diameters match the wavelength(Mie particles)can be effectively trapped within a focused acoustic vortex field,rotating in circular trajectories centered at the vortex center.This research significantly expands the scope of acoustic vortex manipulation for larger particles and introduces a novel implementation strategy with potential applications in targeted drug delivery for clinical adjuvant therapy.
文摘1.Challenges Thermoacoustic instability in combustors arises from the interaction between sound waves and unsteady heat release,commonly found in systems like gas turbines and aeroengines.This instability leads to undesirable consequences such as structural damage and performance deterioration.The challenge lies in predicting and mitigating these instabilities due to the complex interplay of various physical phenomena like acoustic propagation,turbulent flow,and combustion chemistry,which are summarized in detail in Aimee S.Morgans and Dong Yang's published article.
基金supported by the National Key R&D Program of China under grant 2023YFF0715303in part by the National Natural Science Foundation of China under Grant Nos.62305148,62105140,62022037,and 61775028+2 种基金in part by the Department of Science and Technology of Guangdong Province under Grant Nos.2019ZT08Y191 and 2022B1212010003in part by the Shenzhen Science and Technology Program under Grant Nos.JCYJ20220530114010023,RCJC20231211090039066,20231116104616001,KQTD20190929172743294,JCYJ20230807093105010,RCBS20231211090802011in part by the Startup Grant from Southern University of Science and Technology under Grant No.PDJH2021C008.
文摘Ultrasound neuromodulation is a powerful tool for brain investigation and holds great promise for treating brain diseases.However,due to the heterogeneous acoustic properties of skulls,existing ultrasound neuromodulation faces the challenge of severe transcranial acoustic attenuation.To overcome such limitations,we report an implantable bio-chip for visible and controllable mi-crowave-induced transcranial acoustic generation(MI-tAG).The bio-chip is soft,flexible,and biocompatible,with a thickness of 3mm,making it suitable for human intracranial implantation.The constituted fluid channels can cover an area of 50 mm×60 mm,enabling widefield neuronstimulation.The particles filled in the fluid channels have both high microwave absorption.ensuring efficient ultrasound generation,and magnetism,allowing noncontact and flexible ma-nipulation by external magnetic fields.The experimental results demonstrate that the optimal MI-tAG can be realized by the combination of particles arranged in a linear pattern and corre-sponding illumination via a linearly polarized microwave.Stability evaluation indicates that the particles can maintain a consistent acoustic intensity without degradation for at least seven days.The results of in vitro and in vivo experiments show that the MII-tAG can manipulate ultrasound sources and visibly locate them in real time.This study provides a potential innovative approach for future ultrasound neuromodulation,inspiring the development of more useful methods to advance brain research.This study introduces a promising innovative approach for transcranial acoustic generation,potentially inspiring the development of more effective methods for ad-vancing ultrasound neuromodulation.
基金supported by the Shanxi Scholarship Council of China(Grant No.2023-036)the Natural Science Foundation of Shanxi Province(Grant No.202303021222020).
文摘This study explores a sensitivity analysis method based on the boundary element method(BEM)to address the computational complexity in acoustic analysis with ground reflection problems.The advantages of BEM in acoustic simulations and its high computational cost in broadband problems are examined.To improve efficiency,a Taylor series expansion is applied to decouple frequency-dependent terms in BEM.Additionally,the SecondOrder Arnoldi(SOAR)model order reduction method is integrated to reduce computational costs and enhance numerical stability.Furthermore,an isogeometric sensitivity boundary integral equation is formulated using the direct differentiation method,incorporating Cauchy principal value integrals and Hadamard finite part integrals to handle singularities.The proposed method improves the computational efficiency,and the acoustic sensitivity analysis provides theoretical support for further acoustic structure optimization.
基金Supported by Important Project of Science and Technology of Zhejiang Province(2008C12056)~~
文摘[Objective] The aim was to study the effects of different acoustic frequency of insect sound （IS） and insect-music mixed sound （MS） treatment on the growth of 6 kinds of vegetables.[Method] The insect acoustic group,insect-music mixed group and normal control group were designed to determine the related indices of 6 kinds of vegetables in unified management regularly.[Result] After different acoustic frequency treatment,besides soybean plant height,dry root weight of cabbage and greengrocery,there was significant difference of plant height,fresh weight and dry weight between the other vegetables and control.Under acoustic frequency treatment,the growth situations of six kinds of vegetables were better than control.In the growth period,acoustic frequency treatment could promote height growth （except soybean） and edible part yield.[Conclusion] Both of IS and MS could promote the plant growth,but their effects had difference.
基金the Fundamental Research Foundation of Harbin Engineering University, (grant number HEUF 04017)
文摘A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.11634006 and 81127901)+1 种基金the Fund from the High-Performance Computing Center of Collaborative Innovation Center of Advanced Microstructuresthe Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Acoustic orbital angular momentum(OAM)associated with helicoidal wavefront recently attracts rapidly-growing attentions,offering a new degree of freedom for acoustic manipulation.Due to the unique dynamical behavior and inherent mode orthogonality of acoustic OAM,its harnessing is of fundamental interests for wave physics,with great potential in a plethora of applications.The recent advance in materials physics further boosts efforts into controlling OAM-carrying acoustic vortices,especially acoustic metasurfaces with planar profile and subwavelength thickness.Thanks to their un-conventional acoustic properties beyond attainable in the nature,acoustic artificial structures provide a powerful platform for new research paradigm for efficient generation and diverse manipulation of OAM in ways not possible before,enabling novel applications in diverse scenarios ranging from underwater communication to object manipulation.In this article,we present a comprehensive view of this emerging field by delineating the fundamental physics of OAM-metasurface interac-tion and recent advances in the generation,manipulation,and application of acoustic OAM based on artificial structures,followed by an outlook for promising future directions and potential practical applications.
基金supported by the National Natural Science Foundation of China(Nos.52374080 and 52404201)。
文摘In the process of deep engineering excavation,the mechanical properties of rock are significantly influenced by the coupled effects of water and high stress,which greatly increase construction difficulty.To more accurately investigate the impact of water disturbance on the failure process of dry rock under high stress and the failure mechanisms of saturated rock in underwater environments,a water environment test chamber and a prefabricated borehole specimen through-water device were designed.A series of experiments were conducted,including uniaxial tests,water-disturbed granite cylinder tests,and through-water disturbance tests on prefabricated hole square specimens.The results showed that the acoustic emission(AE)hits and accumulated energy after the through-water disturbance at the same time were 8.77 and 12.08 times higher than before the disturbance,respectively.And water disturbance increased the proportion of tensile failure and reduced the proportion of shear failure.A key observation was that AE events were mainly generated in the permeation areas near the borehole.The main reason was that under high stress,the weakening effect of water led to the failure of the local mineral structure of the rock,promoting crack extension and triggering overall instability.Notably,failure of the saturated specimens underwater was only observed when the applied load approached the saturation strength of the prefabricated hole square specimens.The study results provide an important theoretical basis for understanding the damage mechanism of water-disturbed rocks in deep engineering,and have significant implications for the design and construction of engineering.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U20A20266 and 12302503)Scientific and technological research projects in Sichuan province(Grant No.2024NSFSC0973).
文摘The loaded rock experiences multiple stages of deformation.It starts with the formation of microcracks at low stresses(crack initiation,CI)and then transitions into unstable crack propagation(crack damage,CD)near the ultimate strength.In this study,both the acoustic emission method(AEM)and the ultrasonic testing method(UTM)were used to examine the characteristics of AE parameters(b-value,peak frequency,frequency-band energy ratio,and fractal dimension)and ultrasonic(ULT)properties(velocity,amplitude,energy attenuation,and scattering attenuation)of bedded shale at CI,CD,and ultimate strength.The comparison involved analyzing the strain-based method(SBM),AEM,and UTM to determine the thresholds for damage stress.A fuzzy comprehensive evaluation model(FCEM)was created to describe the damage thresholds and hazard assessment.The results indicate that the optimal AE and ULT parameters for identifying CI and CD stress are ringing count,ultrasonic amplitude,energy attenuation,and scattering attenuation of the S-wave.Besides,damage thresholds were detected earlier by AE monitoring,ranging from 3 MPa to 10 MPa.CI and CD identified by UTM occurred later than SBM and AEM,and were in the range of 12 MPa.The b-value,peak frequency,energy ratio in the low-frequency band(0e62.5 kHz),correlation dimension,and sandbox dimension showed low values at the peak stress,while the energy ratio in a moderate-frequency band(187.5e281.25 kHz)and amplitude showed high values.The successful application of FCEM to laboratory testing of shales has demonstrated its ability to quantitatively identify AE/ULT precursors of seismic hazards associated with rock failure.
基金National Natural Science Foundation of China(No.51705545)。
文摘The active sound absorption technique excels in mitigating low-frequency sound waves,yet it falls short when dealing with medium and high-frequency sound waves.To enhance the sound-absorbing effect of medium and high-frequency sound waves,a novel semi-active sound absorption method has been introduced.This method modulates the surface impedance of a loudspeaker positioned behind the sound-absorbing material,thereby altering the sound absorption coefficient.The theoretical sound absorption coefficient is calculated using MATLAB and compared with the experimental one.Results show that the method can effectively modulates the absorption coefficient in response to varying incident sound wave frequencies,ensuring that it remains at its peak value.
文摘The effects of the temperature,salinity,and fluid type on the acoustic characteristics of turbulent flow around a circular cylinder were numerically investigated for the Reynolds numbers of 2.25×10^(4),4.5×10^(4),and 9.0×10^(4).Various hybrid methodsReynolds-averaged Navier-Stokes(BANS)with the Ffowcs Williams and Hawkings(FWH)model,detached-eddy simulation(DES)with FWH,and large-eddy simulation with FWH-were used for the acoustic analyses,and their performances were evaluated by comparing the predicted results with the experimental data.The DES-FWH hybrid method was found to be suitable for the aero-and hydro-acoustic analysis.The hydro-acoustic measurements were performed in a silent circulation channel for the Reynolds number of 2.25×10^(4).The results showed that the fluid temperature caused an increase in the overall sound pressure levels(OASPLs)and the maximum sound pressure levels(SPL_(T))for the air medium;however,it caused a decrease for the water medium.The salinity had smaller effects on the OASPL and SPLT compared to the temperature.Moreover,the main peak frequency increased with the air temperature but decreased with the water temperature,and it was nearly constant with the change in the salinity ratio.The SPLT and OASPL for the water medium were quite higher than those for the air medium.
