Intensity of cavitation is significant in ultrasonic wastewater treatment,but is complicated to measure.A time difference based method of ultrasonic cavitation measurement is proposed.The time differences at different...Intensity of cavitation is significant in ultrasonic wastewater treatment,but is complicated to measure.A time difference based method of ultrasonic cavitation measurement is proposed.The time differences at different powers of 495 kHz ultrasonic are measured in experiment in comparison with conductimetric method.Simulation results show that time difference and electrical conductivity are both approximately positive proportional to the ultrasonic power.The degradation of PNP solution verifies the availability in wastewater treatment by using ultrasonic.展开更多
A model of a liquid-filled pipe embedded in a porous medium is built to research its wave propagation characteristics,and to analyze the effect of the parameters of porous media on the dispersion.The dispersion equati...A model of a liquid-filled pipe embedded in a porous medium is built to research its wave propagation characteristics,and to analyze the effect of the parameters of porous media on the dispersion.The dispersion equations are established on the basis of the elastic-dynamic theory of the liquid-saturated porous solid.The characteristic of dispersion and the time domain waveform in pipes of different thicknesses and with different porous-medium parameters are discussed theoretically and numerically.Results reveal that the porosity has little impact on dispersion,and the attenuation of guided wave increases with porosity,whilst the porosity influences the displacement amplitude of the time domain waveform.It is hard to detect the permeability variation of the media by the dispersion.The drawn conclusion can provide some theoretical instruction and guidance for the nondestructive testing of buried pipe.展开更多
The second-order harmonic field characteristics at the solid-solid interface with P wave incidence were evaluated according to the second-order potential theory.An isotropic solid-solid interface was established to so...The second-order harmonic field characteristics at the solid-solid interface with P wave incidence were evaluated according to the second-order potential theory.An isotropic solid-solid interface was established to solve the boundary value problem of second-order nonhomogeneous potential equation based on the Lagrange’s method of variation parameters.A numerical computation was performed to analyze the incident angle and second-order harmonic displacement.The results show that the longitudinal wave and transverse wave displacements of second-order harmonic field rapidly increase at a specific incidence angle.Moreover,the special solutions of displacement abruptly change for incident angle θw.Finally,the effect of boundary surface on second-order harmonic sound field is also discussed.展开更多
In order to understand the viscoelasticity of material, this research has been conducted to study the propagation characteristics of viscoelastic Rayleigh wave theoretically. A model is presented for the pulsed laser ...In order to understand the viscoelasticity of material, this research has been conducted to study the propagation characteristics of viscoelastic Rayleigh wave theoretically. A model is presented for the pulsed laser generation of ultrasound on viscoelastic medium surface. Referred to the Kelvin model, the frequency equation and the normal displacement of viscoelastic Rayleigh wave were derived, the influence of the viscoelastic modulus on dispersion and attenuation was discussed. From the theoretical calculation, it is shown that the effect of viscoelasticity on the attenuation of Rayleigh wave is more than that on its dispersion. In the case of a weak viscosity, the attenuation of viscoelastic Rayleigh wave is directly proportional to viscosity modulus; the effect of shear viscosity on the attenuation is much more than that of bulk viscosity. The transient response of viscoelastic Rayleigh wave was also simulated using Laplace and Hankel inversion transform, which are showed in good agreement with the theoretic predictions. The model provides a useful tool for the determination of viscoelastic parameters of medium.展开更多
The propagation characteristics of the low-frequency axisymmetric waves in buried fluid-filled pipes are investigated theoretically,based on the Kennard thin-walled shell equations,the Helmholtz equation,and the Kelvi...The propagation characteristics of the low-frequency axisymmetric waves in buried fluid-filled pipes are investigated theoretically,based on the Kennard thin-walled shell equations,the Helmholtz equation,and the Kelvin-Voigt linear viscoelastic model.Analytic expressions of the phase velocity are derived for both the fluid-dominated wave and the shell-compressed wave under lubricated contact,via considering the surrounding soil as a viscoelastic medium.The dispersion and attenuation curves of the two wave types are obtained and verified numerically.The ratio of the radial pipe wall displacements is analyzed,with particular emphasis on the effects of the thickness-to-radius ratio and the quality factor on the dispersion and attenuation characteristics of the fluid-dominated wave.The results show that the viscoelastic property has slight effects on the phase velocities of the two wave types,but it influences the attenuation severely.The fluid-dominated wave influences the radial pipe wall displacement significantly and is the primary carrier of leakage noise energy;its phase velocity increases as a function of the thickness-to-radius ratio while the attenuation decreases.It also shows that the dispersion and attenuation of the fluid-dominated wave decrease as a function of the quality factor.The work will provide insights and guidance for the leakage detection of buried fluid-filled pipes.展开更多
This paper devotes to investigate the propagation characteristics of the interface wave on the liquid-immersed porous cylinder, and special emphasis is paid on the dependence of the dispersion relation on the porous m...This paper devotes to investigate the propagation characteristics of the interface wave on the liquid-immersed porous cylinder, and special emphasis is paid on the dependence of the dispersion relation on the porous media parameters. A model of liquid-immersed porous cylinder is established theoretically. Based on the elastic-dynamic theory of liquid-saturated porous solid and wave theory, the dispersion curves and transient response of open-pores and sealed-pores are simulated numerically, and their dependence on the cylinder radius and porous medium parameters are analyzed. The results show that the Stoneley-Scholte wave can be clearly distinguished with other waves in the time domain, and the Stoneley-Scholte wave dispersion relates intimately with the porosity of the porous medium and cylinder radius, whilst the permeability of the media has little effect on the dispersion property.展开更多
基金Supported by the National Natural Science Foundation of China(No.11274092,11274091,11304026)the Fundamental Research Funds for the Central Universities(No.14B10128)
文摘Intensity of cavitation is significant in ultrasonic wastewater treatment,but is complicated to measure.A time difference based method of ultrasonic cavitation measurement is proposed.The time differences at different powers of 495 kHz ultrasonic are measured in experiment in comparison with conductimetric method.Simulation results show that time difference and electrical conductivity are both approximately positive proportional to the ultrasonic power.The degradation of PNP solution verifies the availability in wastewater treatment by using ultrasonic.
基金supported by the National Natural Science Foundation of China(11574072)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(SKLA201913)。
文摘A model of a liquid-filled pipe embedded in a porous medium is built to research its wave propagation characteristics,and to analyze the effect of the parameters of porous media on the dispersion.The dispersion equations are established on the basis of the elastic-dynamic theory of the liquid-saturated porous solid.The characteristic of dispersion and the time domain waveform in pipes of different thicknesses and with different porous-medium parameters are discussed theoretically and numerically.Results reveal that the porosity has little impact on dispersion,and the attenuation of guided wave increases with porosity,whilst the porosity influences the displacement amplitude of the time domain waveform.It is hard to detect the permeability variation of the media by the dispersion.The drawn conclusion can provide some theoretical instruction and guidance for the nondestructive testing of buried pipe.
基金supported by the National Natural Science Foundation of China (11574072,11274091)the Key Research Project of Jiangsu Province (BE2016056)。
文摘The second-order harmonic field characteristics at the solid-solid interface with P wave incidence were evaluated according to the second-order potential theory.An isotropic solid-solid interface was established to solve the boundary value problem of second-order nonhomogeneous potential equation based on the Lagrange’s method of variation parameters.A numerical computation was performed to analyze the incident angle and second-order harmonic displacement.The results show that the longitudinal wave and transverse wave displacements of second-order harmonic field rapidly increase at a specific incidence angle.Moreover,the special solutions of displacement abruptly change for incident angle θw.Finally,the effect of boundary surface on second-order harmonic sound field is also discussed.
基金the Natinal Natural Science Foundation of China (10234060,10134020)
文摘In order to understand the viscoelasticity of material, this research has been conducted to study the propagation characteristics of viscoelastic Rayleigh wave theoretically. A model is presented for the pulsed laser generation of ultrasound on viscoelastic medium surface. Referred to the Kelvin model, the frequency equation and the normal displacement of viscoelastic Rayleigh wave were derived, the influence of the viscoelastic modulus on dispersion and attenuation was discussed. From the theoretical calculation, it is shown that the effect of viscoelasticity on the attenuation of Rayleigh wave is more than that on its dispersion. In the case of a weak viscosity, the attenuation of viscoelastic Rayleigh wave is directly proportional to viscosity modulus; the effect of shear viscosity on the attenuation is much more than that of bulk viscosity. The transient response of viscoelastic Rayleigh wave was also simulated using Laplace and Hankel inversion transform, which are showed in good agreement with the theoretic predictions. The model provides a useful tool for the determination of viscoelastic parameters of medium.
基金supported by the National Natural Science Foundation of China(12174085)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(SKLA201913)。
文摘The propagation characteristics of the low-frequency axisymmetric waves in buried fluid-filled pipes are investigated theoretically,based on the Kennard thin-walled shell equations,the Helmholtz equation,and the Kelvin-Voigt linear viscoelastic model.Analytic expressions of the phase velocity are derived for both the fluid-dominated wave and the shell-compressed wave under lubricated contact,via considering the surrounding soil as a viscoelastic medium.The dispersion and attenuation curves of the two wave types are obtained and verified numerically.The ratio of the radial pipe wall displacements is analyzed,with particular emphasis on the effects of the thickness-to-radius ratio and the quality factor on the dispersion and attenuation characteristics of the fluid-dominated wave.The results show that the viscoelastic property has slight effects on the phase velocities of the two wave types,but it influences the attenuation severely.The fluid-dominated wave influences the radial pipe wall displacement significantly and is the primary carrier of leakage noise energy;its phase velocity increases as a function of the thickness-to-radius ratio while the attenuation decreases.It also shows that the dispersion and attenuation of the fluid-dominated wave decrease as a function of the quality factor.The work will provide insights and guidance for the leakage detection of buried fluid-filled pipes.
基金supported by the National Natural Science Foundation of China(11574072,11274091)the Key Research Project of Jiangsu Province(BE2016056)
文摘This paper devotes to investigate the propagation characteristics of the interface wave on the liquid-immersed porous cylinder, and special emphasis is paid on the dependence of the dispersion relation on the porous media parameters. A model of liquid-immersed porous cylinder is established theoretically. Based on the elastic-dynamic theory of liquid-saturated porous solid and wave theory, the dispersion curves and transient response of open-pores and sealed-pores are simulated numerically, and their dependence on the cylinder radius and porous medium parameters are analyzed. The results show that the Stoneley-Scholte wave can be clearly distinguished with other waves in the time domain, and the Stoneley-Scholte wave dispersion relates intimately with the porosity of the porous medium and cylinder radius, whilst the permeability of the media has little effect on the dispersion property.
