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
In the study of the surface instability of a vertically oscillating granular layer,we obtained experimentally the phase diagram for the surface states of the layer in the driving frequency-acceleration plane,and measu...In the study of the surface instability of a vertically oscillating granular layer,we obtained experimentally the phase diagram for the surface states of the layer in the driving frequency-acceleration plane,and measured the dispersion relation for the surface waves in a granular layer in comparison to that in viscous fluids.Our experiments show that the onset dimensionless acceleration increases with the driving frequency,and the wavelength of the surface waves increases with the depth of granular layer.These experimental results are in agreement with our theoretical model qualitatively.展开更多
Thermal diffusivity has been investigated in a manganite thin film La0.6Sr0.4MnO3 by means of transient grating （TG） technique at room temperature. A new method, which is generalized to two-layered samples of the th...Thermal diffusivity has been investigated in a manganite thin film La0.6Sr0.4MnO3 by means of transient grating （TG） technique at room temperature. A new method, which is generalized to two-layered samples of the thin film deposited on a semi-infinite substrate, is established to fit the TG signals. The thermal diffusivity of the Lao.6Sro.4MnO3 thin film with a thickness of 200nm on an MgO （100） substrate is determined to be 0.92mm^2/s, which is slightly smaller than that of the single crystal sample （1 mm^2/s）.展开更多
Three kinds of resonant modes of a single layered circular elastic cylinder embedded in the elastic medium are analysed by considering the oscillation of the scatter＇s core, based on the fact that the core moves as a...Three kinds of resonant modes of a single layered circular elastic cylinder embedded in the elastic medium are analysed by considering the oscillation of the scatter＇s core, based on the fact that the core moves as a rigid body when the shell material is very compliant. The resonant frequencies of the single resonator acquired by our method are in good agreement with those calculated by the local interaction simulation approach （LISA） for the local resonant phononic crystal. Therefore, the local resonant characteristics of a single layered circular elastic cylinder can be used to evaluate the resonant frequencies of the phononic crystal. The effects of the geometrical and physical parameters of the shell and the core are also studied in details. This work is significant for designing the locally resonant phononic crystal based on the local resonant characteristics of the single resonator, and the resonant frequencies can be tuned by selecting the geometrical sizes and the materials.展开更多
A dynamical model is presented for a thin layer of granular materials similar to that for shallow viscous fluid.We have obtained analytically the expressions for the“thermal expansion”,dispersion relation,and depend...A dynamical model is presented for a thin layer of granular materials similar to that for shallow viscous fluid.We have obtained analytically the expressions for the“thermal expansion”,dispersion relation,and dependence of instability onset on driving frequency and viscosity,which are in agreement with experiments.The numerical calculation for the nonlinear problem reproduces the experimental phenomena for a one-dimensional system.展开更多
Photoconductivity decay(PCD)in semiconductors is investigated by a pulsed laser with an unfocused or a focused beam.The rigorous solutions of PCD under illumination with two different types of laser beams,unfocused an...Photoconductivity decay(PCD)in semiconductors is investigated by a pulsed laser with an unfocused or a focused beam.The rigorous solutions of PCD under illumination with two different types of laser beams,unfocused and focused,are derived separately.The experimental results of PCD are compared with the theory using Ge-based GaN under illumination of a pulsed Nd:YAG laser at 355nm.The experimental and numerical results are in good agreement.展开更多
Based on the introduction of international progress, our investigations on acoustic cavitation have been reported. Firstly we considered the cavity's dynamics under the drive of the asymmetrical acoustic pressure....Based on the introduction of international progress, our investigations on acoustic cavitation have been reported. Firstly we considered the cavity's dynamics under the drive of the asymmetrical acoustic pressure. An aspheric dynamical model was proposed and a new stable and aspheric solution was found in numerical simulation of the theoretical framework of the aspheric model. Then, a dual Mie-scattering technique was developed to measure the cavity's aspheric pulsation. A significant asynchronous pulsation signal between two Mie-scattering channels was caught in the case of large cavity driven by low acoustic pressure. As a direct deduction, we observed an evidence of cavity's aspheric pulsation. Furthermore, we studied the dependency of the asynchronous pulsation signal on the various parameters, such as the amplitude and frequency of the driving acoustic pressure, and the surface tension, viscosity and gas concentration of the liquid. Finally, we introduced a new numeric imaging technique to measure the shapes of the periodic pulsation cavities. The time-resolution was in the order of 20 ns, one order of magnitude lower than that in the previous work, say, 200 ns.展开更多
Analysis of multiscale entropy(MSE) and multiscale standard deviation(MSD) are performed for both the heart rate interval series and the interval increment series.For the interval series,it is found that,it is impract...Analysis of multiscale entropy(MSE) and multiscale standard deviation(MSD) are performed for both the heart rate interval series and the interval increment series.For the interval series,it is found that,it is impractical to discriminate the diseases of atrial fibrillation(AF) and congestive heart failure(CHF) unambiguously from the healthy.A clear discrimination from the healthy,both young and old,however,can be made in the MSE analysis of the increment series where we find that both CHF and AF sufferers have significantly low MSE values in the whole range of time scales investigated,which reveals that there are common dynamic characteristics underlying these two different diseases.In addition,we propose the sample entropy(SE) corresponding to time scale factor 4 of increment series as a diag-nosis index of both AF and CHF,and the reference threshold is recommended.Further indication that this index can help discriminate sensitively the mild heart failure(cardiac function classes 1 and 2) from the healthy gives a clue to early clinic diagnosis of CHF.展开更多
A unified perturbation theory is developed here for calculating solitary waves of all heights by series expansion of base flow variables in powers of a small base parameter to eighteenth order for the one-parameter fa...A unified perturbation theory is developed here for calculating solitary waves of all heights by series expansion of base flow variables in powers of a small base parameter to eighteenth order for the one-parameter family of solutions in exact form, with all the coefficients determined in rational numbers. Comparative studies are pursued to investigate the effects due to changes of base parameters on （i） the accuracy of the theoretically predicted wave properties and （ii） the rate of convergence of perturbation expansion. Two important results are found by comparisons between the theoretical predictions based on a set of parameters separately adopted for expansion in turn. First, the accuracy and the convergence of the perturbation expansions, appraised versus the exact solution provided by an earlier paper [1] as the standard reference, are found to depend, quite sensitively, on changes in base parameter. The resulting variations in the solution are physically displayed in various wave properties with differences found dependent on which property （e.g. the wave amplitude, speed, its profile, excess mass, momentum, and energy）, on what range in value of the base, and on the rank of the order n in the expansion being addressed. Secondly, regarding convergence, the present perturbation series is found definitely asymptotic in nature, with the relative error δ （n） （the relative mean-square difference between successive orders n of wave elevations） reaching a minimum, δm at a specific order, n = n both depending on the base adopted, e.g. nm,α= 11-12 based on parameter α （wave amplitude）, nm,δ = 15 on δ （amplitude-speed square ratio）, and nm.ε= 17 on ε （ wave number squared）. The asymptotic range is brought to completion by the highest order of n = 18 reached in this work.展开更多
Based on a series of spectral measurements of sonoluminescence, this paper investigates parametric dependence of the line emissions in single bubble sonoluminescence (SBSL) and multi-bubble sonoluminescence (MBSL). Th...Based on a series of spectral measurements of sonoluminescence, this paper investigates parametric dependence of the line emissions in single bubble sonoluminescence (SBSL) and multi-bubble sonoluminescence (MBSL). The experiments show that the intensities of the OH* radical line, the sodium line and the noble gas lines in SBSL are relevant to the driving pressure of the acoustic field and the concentration of the noble gases dissolved in host liquids. The intensity of line emissions in total spectrum increases with the decreasing driving pressure and the increasing concentration of noble gases. Parametric dependence of line emissions in MBSL consists with that in SBSL. Line emissions in sonoluminescence should correspond to lower temperature inside the bubbles. SBSL and MBSL share the same spectral structure, and the difference between them found by previous experiments should result from the different temperatures inside bubbles.展开更多
The current work proposes a model describing the dynamics of coated microbubbles, which simplifies the traditional three-layer model to a two-layer one by introducing a visco-elastic interface with variable surface te...The current work proposes a model describing the dynamics of coated microbubbles, which simplifies the traditional three-layer model to a two-layer one by introducing a visco-elastic interface with variable surface tension coefficients to connect the gas zone and the liquid zone. In the modified model, the traditional two interfaces boundary conditions are combined into one to simplify the description of the bubble. Moreover, the surface tension coefficient is defined as a function of bubble radius with lower and upper limits, which are related to the buckling and rupture mechanisms of the bubble. Further discussion is made regarding the effects resulting from the change of the surface tension coefficient on bubble dynamics. The dynamic responses of Optison and Sonozoid microbubbles, measured experimentally based on light scattering technology (adapted from previously published work), are simulated using both classic three-layer models (e.g. Church's model) and simplified model. The results show that our simplified model works as well as the Church's model.展开更多
The 9thInternational Symposium on Modern Acoustics was held in Nanjing,China,on May 19-22,2012.The symposium was organized by the Key Laboratory of Modern A-coustics and Institute of Acoustics of Nanjing University,th...The 9thInternational Symposium on Modern Acoustics was held in Nanjing,China,on May 19-22,2012.The symposium was organized by the Key Laboratory of Modern A-coustics and Institute of Acoustics of Nanjing University,the Acoustical Society of China,展开更多
The classical Faraday experiment is a tractable problem in nonlinear physics,and its rich spectrum of nonlinear phenomena has made it a prototype in studying nonlinear wave dynamics in general.Here we report the ob se...The classical Faraday experiment is a tractable problem in nonlinear physics,and its rich spectrum of nonlinear phenomena has made it a prototype in studying nonlinear wave dynamics in general.Here we report the ob servation of a new type of subharmonic resonances which occurs at some smaller fractional frequencies,such asν/3,ν/4,andν/6,whereνis the forcing frequency.As a result of these resonances,the lower-order surface-wave modes whose eigenfrequencies are close to the fractional frequencies participate into the wave motions.Our theory involving quadratically nonlinear mode couplings shows that an already excited mode itself can act as a parametric source on the lower-order primary modes,thus leading to the cascading subharmonic resonances.展开更多
We set up a reflective nonlinear acoustic microscope to contour the quantitative adhesion at a bonded solid-solid interface by a contact acoustic nonlinearity （CAN） method. The principle of the reflective nonlinear ...We set up a reflective nonlinear acoustic microscope to contour the quantitative adhesion at a bonded solid-solid interface by a contact acoustic nonlinearity （CAN） method. The principle of the reflective nonlinear acoustic microscope is described. After the vibration amplitude of the incident, focusing wave at the bonded interface is calculated, the standard adhesion with a complete bonding state is established by the tension test, the reflective CAN parameter is calibrated, and the quantitative contour of the adhesion at the interface can be obtained. The experimental contours of two samples are also presented. Compared with the transmitted microscope, the reflective one is more convenient and more suitable for practical applications.展开更多
A novel sifting method based on the concept of the 'local centroids' of a signal is developed for empirical mode decomposition (EMD), with the aim of reducing the mode-mixing effect and decomposing those modes...A novel sifting method based on the concept of the 'local centroids' of a signal is developed for empirical mode decomposition (EMD), with the aim of reducing the mode-mixing effect and decomposing those modes whose frequencies are within an octave. Instead of directly averaging the upper and lower envelopes, as suggested by the original EMD method, the proposed technique computes the local mean curve of a signal by interpolating a set of 'local centroids', which are integral averages over local segments between successive extrema of the signal. With the 'centroid'-based sifting, EMD is capable of separating intrinsic modes of oscillatory components with their frequency ratio ν even up to 0.8, thus greatly mitigating the effect of mode mixing and enhancing the frequency resolving power. Inspection is also made to show that the integral property of the 'centroid'-based sifting can make the decomposition more stable against noise interference.展开更多
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Supported by the Special Funds for Major State Basic Research Projects,the Chinese Nonlinear Science Foundation and the National Natural Science Foundation of China under Grant Nos.19834040 and 19874029.
文摘In the study of the surface instability of a vertically oscillating granular layer,we obtained experimentally the phase diagram for the surface states of the layer in the driving frequency-acceleration plane,and measured the dispersion relation for the surface waves in a granular layer in comparison to that in viscous fluids.Our experiments show that the onset dimensionless acceleration increases with the driving frequency,and the wavelength of the surface waves increases with the depth of granular layer.These experimental results are in agreement with our theoretical model qualitatively.
基金Supported by the National Natural Science Foundation of China under Grant No 10374041, the Program for New Century Excellent Talents in Universities from the Ministry of Education of China under Grant No NECT-04-0456.
文摘Thermal diffusivity has been investigated in a manganite thin film La0.6Sr0.4MnO3 by means of transient grating （TG） technique at room temperature. A new method, which is generalized to two-layered samples of the thin film deposited on a semi-infinite substrate, is established to fit the TG signals. The thermal diffusivity of the Lao.6Sro.4MnO3 thin film with a thickness of 200nm on an MgO （100） substrate is determined to be 0.92mm^2/s, which is slightly smaller than that of the single crystal sample （1 mm^2/s）.
基金Project supported by the Funds for outstanding Youth Researchers from the National Natural Science Foundation of China （Grant No 10125417） and the State Key Development Program for Basic Research of China （Grant No 51307）.
文摘Three kinds of resonant modes of a single layered circular elastic cylinder embedded in the elastic medium are analysed by considering the oscillation of the scatter＇s core, based on the fact that the core moves as a rigid body when the shell material is very compliant. The resonant frequencies of the single resonator acquired by our method are in good agreement with those calculated by the local interaction simulation approach （LISA） for the local resonant phononic crystal. Therefore, the local resonant characteristics of a single layered circular elastic cylinder can be used to evaluate the resonant frequencies of the phononic crystal. The effects of the geometrical and physical parameters of the shell and the core are also studied in details. This work is significant for designing the locally resonant phononic crystal based on the local resonant characteristics of the single resonator, and the resonant frequencies can be tuned by selecting the geometrical sizes and the materials.
基金Supported by the Special Funds for Major State Basic Research Projectsthe Chinese Nonlinear Science Foundationthe National Natural Science Foundation of China under Grant Nos.19834040,19874029 and 10074032.
文摘A dynamical model is presented for a thin layer of granular materials similar to that for shallow viscous fluid.We have obtained analytically the expressions for the“thermal expansion”,dispersion relation,and dependence of instability onset on driving frequency and viscosity,which are in agreement with experiments.The numerical calculation for the nonlinear problem reproduces the experimental phenomena for a one-dimensional system.
基金Supported in part by the National Natural Science Foundation of China under Grant No.19634050。
文摘Photoconductivity decay(PCD)in semiconductors is investigated by a pulsed laser with an unfocused or a focused beam.The rigorous solutions of PCD under illumination with two different types of laser beams,unfocused and focused,are derived separately.The experimental results of PCD are compared with the theory using Ge-based GaN under illumination of a pulsed Nd:YAG laser at 355nm.The experimental and numerical results are in good agreement.
基金This work was supported partially by the National Natural Science Foundation of China (Grant No. 10434070)the Key Project of Ministry of Education of China (Grant No. 103078).
文摘Based on the introduction of international progress, our investigations on acoustic cavitation have been reported. Firstly we considered the cavity's dynamics under the drive of the asymmetrical acoustic pressure. An aspheric dynamical model was proposed and a new stable and aspheric solution was found in numerical simulation of the theoretical framework of the aspheric model. Then, a dual Mie-scattering technique was developed to measure the cavity's aspheric pulsation. A significant asynchronous pulsation signal between two Mie-scattering channels was caught in the case of large cavity driven by low acoustic pressure. As a direct deduction, we observed an evidence of cavity's aspheric pulsation. Furthermore, we studied the dependency of the asynchronous pulsation signal on the various parameters, such as the amplitude and frequency of the driving acoustic pressure, and the surface tension, viscosity and gas concentration of the liquid. Finally, we introduced a new numeric imaging technique to measure the shapes of the periodic pulsation cavities. The time-resolution was in the order of 20 ns, one order of magnitude lower than that in the previous work, say, 200 ns.
基金Supported by the National Natural Science Foundation of China (Grant No. 60701002
文摘Analysis of multiscale entropy(MSE) and multiscale standard deviation(MSD) are performed for both the heart rate interval series and the interval increment series.For the interval series,it is found that,it is impractical to discriminate the diseases of atrial fibrillation(AF) and congestive heart failure(CHF) unambiguously from the healthy.A clear discrimination from the healthy,both young and old,however,can be made in the MSE analysis of the increment series where we find that both CHF and AF sufferers have significantly low MSE values in the whole range of time scales investigated,which reveals that there are common dynamic characteristics underlying these two different diseases.In addition,we propose the sample entropy(SE) corresponding to time scale factor 4 of increment series as a diag-nosis index of both AF and CHF,and the reference threshold is recommended.Further indication that this index can help discriminate sensitively the mild heart failure(cardiac function classes 1 and 2) from the healthy gives a clue to early clinic diagnosis of CHF.
基金The project partly supported by the National Natural Science Foundation of China(19925414,10474045)
文摘A unified perturbation theory is developed here for calculating solitary waves of all heights by series expansion of base flow variables in powers of a small base parameter to eighteenth order for the one-parameter family of solutions in exact form, with all the coefficients determined in rational numbers. Comparative studies are pursued to investigate the effects due to changes of base parameters on （i） the accuracy of the theoretically predicted wave properties and （ii） the rate of convergence of perturbation expansion. Two important results are found by comparisons between the theoretical predictions based on a set of parameters separately adopted for expansion in turn. First, the accuracy and the convergence of the perturbation expansions, appraised versus the exact solution provided by an earlier paper [1] as the standard reference, are found to depend, quite sensitively, on changes in base parameter. The resulting variations in the solution are physically displayed in various wave properties with differences found dependent on which property （e.g. the wave amplitude, speed, its profile, excess mass, momentum, and energy）, on what range in value of the base, and on the rank of the order n in the expansion being addressed. Secondly, regarding convergence, the present perturbation series is found definitely asymptotic in nature, with the relative error δ （n） （the relative mean-square difference between successive orders n of wave elevations） reaching a minimum, δm at a specific order, n = n both depending on the base adopted, e.g. nm,α= 11-12 based on parameter α （wave amplitude）, nm,δ = 15 on δ （amplitude-speed square ratio）, and nm.ε= 17 on ε （ wave number squared）. The asymptotic range is brought to completion by the highest order of n = 18 reached in this work.
基金Supported by the National Natural Science Foundation of China (Grant No. 10434070)
文摘Based on a series of spectral measurements of sonoluminescence, this paper investigates parametric dependence of the line emissions in single bubble sonoluminescence (SBSL) and multi-bubble sonoluminescence (MBSL). The experiments show that the intensities of the OH* radical line, the sodium line and the noble gas lines in SBSL are relevant to the driving pressure of the acoustic field and the concentration of the noble gases dissolved in host liquids. The intensity of line emissions in total spectrum increases with the decreasing driving pressure and the increasing concentration of noble gases. Parametric dependence of line emissions in MBSL consists with that in SBSL. Line emissions in sonoluminescence should correspond to lower temperature inside the bubbles. SBSL and MBSL share the same spectral structure, and the difference between them found by previous experiments should result from the different temperatures inside bubbles.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 10434070, 10704037)Young Scholar Technological Innovation Projects of Jiangsu Province (China) (Grant No. BK2007569)+1 种基金Research Fund for Doctoral Program (for new scholars) of Higher Education of China (Grant No. 20070284070)Ministry of Education Priorities Project (Grant No. 103078)
文摘The current work proposes a model describing the dynamics of coated microbubbles, which simplifies the traditional three-layer model to a two-layer one by introducing a visco-elastic interface with variable surface tension coefficients to connect the gas zone and the liquid zone. In the modified model, the traditional two interfaces boundary conditions are combined into one to simplify the description of the bubble. Moreover, the surface tension coefficient is defined as a function of bubble radius with lower and upper limits, which are related to the buckling and rupture mechanisms of the bubble. Further discussion is made regarding the effects resulting from the change of the surface tension coefficient on bubble dynamics. The dynamic responses of Optison and Sonozoid microbubbles, measured experimentally based on light scattering technology (adapted from previously published work), are simulated using both classic three-layer models (e.g. Church's model) and simplified model. The results show that our simplified model works as well as the Church's model.
文摘The 9thInternational Symposium on Modern Acoustics was held in Nanjing,China,on May 19-22,2012.The symposium was organized by the Key Laboratory of Modern A-coustics and Institute of Acoustics of Nanjing University,the Acoustical Society of China,
基金Supported by the National Natural Science Foundation of China under Grant Nos.19925414,19774029,and 19834040.
文摘The classical Faraday experiment is a tractable problem in nonlinear physics,and its rich spectrum of nonlinear phenomena has made it a prototype in studying nonlinear wave dynamics in general.Here we report the ob servation of a new type of subharmonic resonances which occurs at some smaller fractional frequencies,such asν/3,ν/4,andν/6,whereνis the forcing frequency.As a result of these resonances,the lower-order surface-wave modes whose eigenfrequencies are close to the fractional frequencies participate into the wave motions.Our theory involving quadratically nonlinear mode couplings shows that an already excited mode itself can act as a parametric source on the lower-order primary modes,thus leading to the cascading subharmonic resonances.
基金Supported by the National Natural Science Foundation of China under Grant No 11174144.
文摘We set up a reflective nonlinear acoustic microscope to contour the quantitative adhesion at a bonded solid-solid interface by a contact acoustic nonlinearity （CAN） method. The principle of the reflective nonlinear acoustic microscope is described. After the vibration amplitude of the incident, focusing wave at the bonded interface is calculated, the standard adhesion with a complete bonding state is established by the tension test, the reflective CAN parameter is calibrated, and the quantitative contour of the adhesion at the interface can be obtained. The experimental contours of two samples are also presented. Compared with the transmitted microscope, the reflective one is more convenient and more suitable for practical applications.
基金Project supported by the National Natural Science Foundation of China (No. 10574070)the State Key Laboratory Foundation of China (No. 9140C240207060C24)
文摘A novel sifting method based on the concept of the 'local centroids' of a signal is developed for empirical mode decomposition (EMD), with the aim of reducing the mode-mixing effect and decomposing those modes whose frequencies are within an octave. Instead of directly averaging the upper and lower envelopes, as suggested by the original EMD method, the proposed technique computes the local mean curve of a signal by interpolating a set of 'local centroids', which are integral averages over local segments between successive extrema of the signal. With the 'centroid'-based sifting, EMD is capable of separating intrinsic modes of oscillatory components with their frequency ratio ν even up to 0.8, thus greatly mitigating the effect of mode mixing and enhancing the frequency resolving power. Inspection is also made to show that the integral property of the 'centroid'-based sifting can make the decomposition more stable against noise interference.
