Theoretical studies on the multi-bubble interaction are crucial for the in-depth understanding of the mechanism behind the applications of ultrasound contrast agents （UCAs） in clinics. A two-dimensional （2D） axisy...Theoretical studies on the multi-bubble interaction are crucial for the in-depth understanding of the mechanism behind the applications of ultrasound contrast agents （UCAs） in clinics. A two-dimensional （2D） axisymmetric finite element model （FEM） is developed here to investigate the bubble-bubble interactions for UCAs in a fluidic environment. The effect of the driving frequency and the bubble size on the bubble interaction tendency （viz., bubbles＇ attraction and repulsion）, as well as the influences of bubble shell mechanical parameters （viz., surface tension coefficient and viscosity coefficient） are discussed. Based on FEM simulations, the temporal evolution of the bubbles＇ radii, the bubble-bubble distance, and the distribution of the velocity field in the surrounding fluid are investigated in detail. The results suggest that for the interacting bubble-bubble couple, the overall translational tendency should be determined by the relationship between the driving frequency and their resonance frequencies. When the driving frequency falls between the resonance frequencies of two bubbles with different sizes, they will repel each other, otherwise they will attract each other. For constant acoustic driving parameters used in this paper, the changing rate of the bubble radius decreases as the viscosity coefficient increases, and increases first then decreases as the bubble shell surface tension coefficient increases, which means that the strength of bubble-bubble interaction could be adjusted by changing the bubble shell visco-elasticity coefficients. The current work should provide a powerful explanation for the accumulation observations in an experiment, and provide a fundamental theoretical support for the applications of UCAs in clinics.展开更多
We report the realization of broadband reflected acoustic focusing lenses based on thermoacoustic phased arrays of Bessel-like beams, in which the units of phase manipulation are composed of three rigid insulated boun...We report the realization of broadband reflected acoustic focusing lenses based on thermoacoustic phased arrays of Bessel-like beams, in which the units of phase manipulation are composed of three rigid insulated boundaries and a thermal insulation film in air with different temperatures. Based on these units, we realize a reflected focusing lens which can focus reflected acoustic energy on a line, and its fractional bandwidth can reach about 0.29. In addition, we discuss the influences of the base angle of Bessel-like beam, the number of basic unit, and the variation of unit temperature on focusing performances in details. Furthermore, the reflected focusing lens for the cylindrical acoustic wave based on the Bessel-like beam is also demonstrated. The proposed focusing lens has the advantages of a broad working bandwidth, large focus size,and high robustness, which may provide possibilities for the design and application of acoustic lenses.展开更多
We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effec...We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effective density, refractive index, and phase velocity of the metamaterial indicate that, at the resonant frequency fm, the metamaterial has zero mass density and a phase transmission that is nearly uniform. We present a mechanism for dramatic acoustic energy squeezing and anomalous acoustic transmission by connecting the metamaterial to a normal waveguide with a larger cross-section. It is shown that at a specific frequency f1, transmission enhancement and energy squeezing are achieved despite the strong geometrical mismatch between the metamaterial and the normal waveguide. Moreover, to confirm the energy transfer properties, the acoustic pressure distribution, acoustic wave reflection coefficient, and energy transmission coefficient are also calculated. These results prove that the RINZ metamaterial provides a new design method for acoustic energy squeezing,super coupling, wave front transformation, and acoustic wave filtering.展开更多
This study investigated dissolution processes of cavitation bubbles generated during in vivo shock wave（SW）-induced treatments. Both active cavitation detection（ACD） and the B-mode imaging technique were applied t...This study investigated dissolution processes of cavitation bubbles generated during in vivo shock wave（SW）-induced treatments. Both active cavitation detection（ACD） and the B-mode imaging technique were applied to measure the dissolution procedure of bi Spheres contrast agent bubbles by in vitro experiments. Besides, the simulation of SW-induced cavitation bubbles dissolution behaviors detected by the B-mode imaging system during in vivo SW treatments, including extracorporeal shock wave lithotripsy（ESWL） and extracorporeal shock wave therapy（ESWT）, were carried out based on calculating the integrated scattering cross-section of dissolving gas bubbles with employing gas bubble dissolution equations and Gaussian bubble size distribution. The results showed that（i） B-mode imaging technology is an effective tool to monitor the temporal evolution of cavitation bubbles dissolution procedures after the SW pulses ceased, which is important for evaluation and controlling the cavitation activity generated during subsequent SW treatments within a treatment period;（ii） the characteristics of the bubbles, such as the bubble size distribution and gas diffusion, can be estimated by simulating the experimental data properly.展开更多
Nonlinear science research is a hot point in the world.It has deepened our cognition of determinism and randomicity,simplicity and com-plexity,noise and order and it will profoundly influ-ence the progress of the stud...Nonlinear science research is a hot point in the world.It has deepened our cognition of determinism and randomicity,simplicity and com-plexity,noise and order and it will profoundly influ-ence the progress of the study of natural science,including life science.Life is the most complex nonlinear system and heart is the core of lifecycle system.In the late more than 20 years,nonlinear research on heart electric activities has made much headway.The commonly used parameters are based on chaos and fractal theory,such as correlation dimension,Lyapunov ex-ponent,Kolmogorov entropy and multifractal singu-larity spectrum.This paper summarizes the commonly used methods in the nonlinear study of heart electric signal.Then,considering the shortages of the above tradi-tional nonlinear parameters,we mainly introduce the results on short-term heart rate variability(HRV)signal(500 R-R intervals)and HFECG signal(1-2s).Finally,we point out it is worthwhile to put emphasis on the study of the sensitive nonlinearity parameters of short-term heart electric signal and their dynamic character and clinical effectivity.展开更多
Based on the periodic oscillation of the stable acoustic cavitation bubble, we present a precise measure-ment technique for the bubble evolution. This technique comprises the lighting engineering of pulsing laser beam...Based on the periodic oscillation of the stable acoustic cavitation bubble, we present a precise measure-ment technique for the bubble evolution. This technique comprises the lighting engineering of pulsing laser beam whose phase can be digitally shifted, and the long distance microphotographics. We used a laser, an acousto-optic modulator, a pulse generator, and a long distance microscope. The evolution of a levitated bubble can be directly shown by a series of bubble’s images at different phases. Numerical simulation in the framework of the Rayleigh-Plesset bubble dynamics well supported the experimental result, and the ambient radius of the bubble, an important parameter re-lated to the mass of the gas inside the bubble, was obtained at the same time.展开更多
In this paper, a phase-coded pulse technique is proposed to improve the signal-to-noise ratio (SNR) in the 3rd harmonic imaging in transmis-sion mode, where three pulses with initial phases of 0o, 120o and 240o are tr...In this paper, a phase-coded pulse technique is proposed to improve the signal-to-noise ratio (SNR) in the 3rd harmonic imaging in transmis-sion mode, where three pulses with initial phases of 0o, 120o and 240o are transmitted and their corre-sponding received signals are linearly summed. By means of simulations and measurements, we show that the 3rd harmonic is enhanced by 9.5 dB, whereas the fundamental or the 2nd harmonic components are suppressed; the axial and lateral beam profiles of the processed 3rd harmonics are superior to those of the fundamental or 2nd harmonic components. In addition, this technique is applied to obtain the 3rd harmonic images for two normal and pathological biological tissues in transmission mode. This technique yields a dramatically cleaner and sharper contrast than the images obtained by the traditional fundamental im-aging and the 2nd harmonic imaging, which helps distinguish the normal and pathological states of tis-sues.展开更多
Motivated by the investigation of Brownian motors in excited granular materials that convert chaotic motion of granules into oriented motion of motors, we performed experimental studies to explore the horizontal flow ...Motivated by the investigation of Brownian motors in excited granular materials that convert chaotic motion of granules into oriented motion of motors, we performed experimental studies to explore the horizontal flow in a vertically vibrated granular layer in an asymmetric periodic potential. The horizontal flow exhibits complex behaviors, considered as functions of time, space, and driving parameters, which are essentially caused by a thermal ratchet. We interpret our experimental findings in terms of the granular layer gaining, transferring and losing horizontal momentum through inelastic collisions.展开更多
基金Projects supported by the National Natural Science Foundation of China(Grant Nos.11474161,11474001,116741731,1774166,11774168,81527803,81627802,and 81420108018)the Fundamental Research Funds for the Central Universities,China(Grant No.020414380109)the Qing Lan Project,China
文摘Theoretical studies on the multi-bubble interaction are crucial for the in-depth understanding of the mechanism behind the applications of ultrasound contrast agents （UCAs） in clinics. A two-dimensional （2D） axisymmetric finite element model （FEM） is developed here to investigate the bubble-bubble interactions for UCAs in a fluidic environment. The effect of the driving frequency and the bubble size on the bubble interaction tendency （viz., bubbles＇ attraction and repulsion）, as well as the influences of bubble shell mechanical parameters （viz., surface tension coefficient and viscosity coefficient） are discussed. Based on FEM simulations, the temporal evolution of the bubbles＇ radii, the bubble-bubble distance, and the distribution of the velocity field in the surrounding fluid are investigated in detail. The results suggest that for the interacting bubble-bubble couple, the overall translational tendency should be determined by the relationship between the driving frequency and their resonance frequencies. When the driving frequency falls between the resonance frequencies of two bubbles with different sizes, they will repel each other, otherwise they will attract each other. For constant acoustic driving parameters used in this paper, the changing rate of the bubble radius decreases as the viscosity coefficient increases, and increases first then decreases as the bubble shell surface tension coefficient increases, which means that the strength of bubble-bubble interaction could be adjusted by changing the bubble shell visco-elasticity coefficients. The current work should provide a powerful explanation for the accumulation observations in an experiment, and provide a fundamental theoretical support for the applications of UCAs in clinics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774137 and 51779107)the Six-Talent Peaks Project in Jiangsu Province,China(Grant No.GDZB-019)+2 种基金the China Postdoctoral Science Foundation(Grant No.2017M621643)the Natural Science Foundation of Jiangsu Higher Educational Institutions of China(Grant No.18KJB140003)the Practice Innovation Training Program Projects for Jiangsu University(Grant No.201710299023Z)and for the Industrial Center of Jiangsu University
文摘We report the realization of broadband reflected acoustic focusing lenses based on thermoacoustic phased arrays of Bessel-like beams, in which the units of phase manipulation are composed of three rigid insulated boundaries and a thermal insulation film in air with different temperatures. Based on these units, we realize a reflected focusing lens which can focus reflected acoustic energy on a line, and its fractional bandwidth can reach about 0.29. In addition, we discuss the influences of the base angle of Bessel-like beam, the number of basic unit, and the variation of unit temperature on focusing performances in details. Furthermore, the reflected focusing lens for the cylindrical acoustic wave based on the Bessel-like beam is also demonstrated. The proposed focusing lens has the advantages of a broad working bandwidth, large focus size,and high robustness, which may provide possibilities for the design and application of acoustic lenses.
基金supported by the National Natural Science Foundation of China(Grant Nos.61571222,11104142,and 11474160)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161009)+1 种基金the Qing Lan Project of Jiangsu Province,Chinathe Six Talent Peaks Project of Jiangsu Province,China
文摘We investigate a one-dimensional acoustic metamaterial with a refractive index of near zero（RINZ） using an array of very thin elastic membranes located along a narrow waveguide pipe. The characteristics of the effective density, refractive index, and phase velocity of the metamaterial indicate that, at the resonant frequency fm, the metamaterial has zero mass density and a phase transmission that is nearly uniform. We present a mechanism for dramatic acoustic energy squeezing and anomalous acoustic transmission by connecting the metamaterial to a normal waveguide with a larger cross-section. It is shown that at a specific frequency f1, transmission enhancement and energy squeezing are achieved despite the strong geometrical mismatch between the metamaterial and the normal waveguide. Moreover, to confirm the energy transfer properties, the acoustic pressure distribution, acoustic wave reflection coefficient, and energy transmission coefficient are also calculated. These results prove that the RINZ metamaterial provides a new design method for acoustic energy squeezing,super coupling, wave front transformation, and acoustic wave filtering.
基金Project partially supported by the National Natural Science Foundation of China(Grant Nos.81627802,81473692,81673995,11374155,11574156,11474001,11474161,11474166,and 11674173)Natural Science Foundation of Jiangsu Province,China(Grant No.BK20151007)the Qing Lan Project of Jiangsu Province,China
文摘This study investigated dissolution processes of cavitation bubbles generated during in vivo shock wave（SW）-induced treatments. Both active cavitation detection（ACD） and the B-mode imaging technique were applied to measure the dissolution procedure of bi Spheres contrast agent bubbles by in vitro experiments. Besides, the simulation of SW-induced cavitation bubbles dissolution behaviors detected by the B-mode imaging system during in vivo SW treatments, including extracorporeal shock wave lithotripsy（ESWL） and extracorporeal shock wave therapy（ESWT）, were carried out based on calculating the integrated scattering cross-section of dissolving gas bubbles with employing gas bubble dissolution equations and Gaussian bubble size distribution. The results showed that（i） B-mode imaging technology is an effective tool to monitor the temporal evolution of cavitation bubbles dissolution procedures after the SW pulses ceased, which is important for evaluation and controlling the cavitation activity generated during subsequent SW treatments within a treatment period;（ii） the characteristics of the bubbles, such as the bubble size distribution and gas diffusion, can be estimated by simulating the experimental data properly.
文摘Nonlinear science research is a hot point in the world.It has deepened our cognition of determinism and randomicity,simplicity and com-plexity,noise and order and it will profoundly influ-ence the progress of the study of natural science,including life science.Life is the most complex nonlinear system and heart is the core of lifecycle system.In the late more than 20 years,nonlinear research on heart electric activities has made much headway.The commonly used parameters are based on chaos and fractal theory,such as correlation dimension,Lyapunov ex-ponent,Kolmogorov entropy and multifractal singu-larity spectrum.This paper summarizes the commonly used methods in the nonlinear study of heart electric signal.Then,considering the shortages of the above tradi-tional nonlinear parameters,we mainly introduce the results on short-term heart rate variability(HRV)signal(500 R-R intervals)and HFECG signal(1-2s).Finally,we point out it is worthwhile to put emphasis on the study of the sensitive nonlinearity parameters of short-term heart electric signal and their dynamic character and clinical effectivity.
基金supported by the National Natural Science Foundation of China(Grant Nos.10434070 and 10174036).
文摘Based on the periodic oscillation of the stable acoustic cavitation bubble, we present a precise measure-ment technique for the bubble evolution. This technique comprises the lighting engineering of pulsing laser beam whose phase can be digitally shifted, and the long distance microphotographics. We used a laser, an acousto-optic modulator, a pulse generator, and a long distance microscope. The evolution of a levitated bubble can be directly shown by a series of bubble’s images at different phases. Numerical simulation in the framework of the Rayleigh-Plesset bubble dynamics well supported the experimental result, and the ambient radius of the bubble, an important parameter re-lated to the mass of the gas inside the bubble, was obtained at the same time.
文摘In this paper, a phase-coded pulse technique is proposed to improve the signal-to-noise ratio (SNR) in the 3rd harmonic imaging in transmis-sion mode, where three pulses with initial phases of 0o, 120o and 240o are transmitted and their corre-sponding received signals are linearly summed. By means of simulations and measurements, we show that the 3rd harmonic is enhanced by 9.5 dB, whereas the fundamental or the 2nd harmonic components are suppressed; the axial and lateral beam profiles of the processed 3rd harmonics are superior to those of the fundamental or 2nd harmonic components. In addition, this technique is applied to obtain the 3rd harmonic images for two normal and pathological biological tissues in transmission mode. This technique yields a dramatically cleaner and sharper contrast than the images obtained by the traditional fundamental im-aging and the 2nd harmonic imaging, which helps distinguish the normal and pathological states of tis-sues.
文摘Motivated by the investigation of Brownian motors in excited granular materials that convert chaotic motion of granules into oriented motion of motors, we performed experimental studies to explore the horizontal flow in a vertically vibrated granular layer in an asymmetric periodic potential. The horizontal flow exhibits complex behaviors, considered as functions of time, space, and driving parameters, which are essentially caused by a thermal ratchet. We interpret our experimental findings in terms of the granular layer gaining, transferring and losing horizontal momentum through inelastic collisions.
