In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of...In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of thin plates and electromagnetic field theory,the nonlinear vibration differential equation of the plate is obtained by using the Hamilton′s principle and the Galerkin method.Then the boundary condition in which the longer opposite sides are clamped and hinged is considered.The dimensionless nonlinear differential equations are solved by using the method of multiple scales,and the analytical solution is given.In addition,the stability analysis is also carried out by using Lyapunov stability theory.Through numerical analysis,the variation curves of system resonance amplitude with frequency tuning parameter,magnetic field strength and external excitation amplitude are obtained.Different parameters that have significant effects on the response of the system,such as the thickness,the axial velocity,the magnetic field intensity,the position,and the frequency of external excitation,are considered and analyzed.The results show that the system has multiple solution regions and obvious nonlinear coupled characteristics.展开更多
In the present paper,the simultaneous resonance of a cylindrical bubble under triple-frequency acoustic excitation is investigated theoretically.Specifically,based on the multi-scale method,the dimensionless oscillati...In the present paper,the simultaneous resonance of a cylindrical bubble under triple-frequency acoustic excitation is investigated theoretically.Specifically,based on the multi-scale method,the dimensionless oscillation equations and the second-order analytical solutions of the primary-subharmonic-subharmonic(PRI-SUB-SUB),primary-superharmonic-superharmonic(PRI-SUPER-SUPER)simultaneous resonances are obtained.Based on the analysis of the frequency response,the nonlinear dynamic behavior of the cylindrical bubble and its influencing factors are analyzed.The primary conclusions include:(1)Under triple-frequency acoustic excitation,the frequency response of PRI-SUB-SUB presents a single peak,and that of PRI-SUPER-SUPER presents two peaks.(2)The polytropic exponent affects both the peak value and position of the resonance peak in the frequency response.(3)The unstable region in frequency response curve of the simultaneous resonance is significantly affected by the total amplitude and equilibrium radius,presenting a positive correlation.展开更多
In this study,analytical and numerical methods are applied to investigate the dynamic response of an axially moving plate subjected to parametric and forced excitation.Based on the classical thin plate theory,the gove...In this study,analytical and numerical methods are applied to investigate the dynamic response of an axially moving plate subjected to parametric and forced excitation.Based on the classical thin plate theory,the governing equation of the plate coupled with fluid is established and further discretized through the Galerkin method.These equations are solved using the method of multiple scales to obtain amplitude-frequency curves and phase-frequency curves.The stability of steady-state response is examined using Lyapunov’s stability theory.In addition,numerical analysis is employed to validate the results of analytical solutions based on the Runge-Kutta method.The multi-value and stability of periodic solutions are verified through stable periodic orbits.Detailed parametric studies show that proper selection of system parameters enables the system to stay in primary resonance or simultaneous resonance,and the state of the system can switch among different periodic motions,contributing to the optimization of fluid-structure interaction system.展开更多
In the present paper,two-and three-dimensional numerical simulations of the flow interference between four cylinders in an in-line square arrangement at Re = 200 are performed.Assisted with the two-dimensional(2-D) nu...In the present paper,two-and three-dimensional numerical simulations of the flow interference between four cylinders in an in-line square arrangement at Re = 200 are performed.Assisted with the two-dimensional(2-D) numerical simulation,the mean and fluctuating forces,Strouhal number(St) and vortex shedding pattern in the wake for each cylinder were analyzed with the spacing ratio(L /D) ranging from 1.5 to 6.0.It was found that,four different vortex modes(viz.,flip-flopping,shielding anti-phase-synchronized,in-phasesynchronized and anti-phase-synchronized) gradually appear with the increase of the L/D ratio.The average drag coefficient of the upstream cylinders is larger than that of the downstream cylinders,while the downstream cylinders usually undergo serious fluctuating forces.When the L/D ratio ranges from 3.0 to 4.0,the dominant frequency of the drag coefficient is equal to the value of St of upstream cylinders.This indicates that a simultaneous resonance in the in-flow and cross-flow directions may occur for some single structures of a multi-body oscillating system.For the 3-D numerical simulation,the L/D and aspect ratios are kept constant as 5.0 and 10,respectively.It was found that some vortices are formed in the wake of the upstream cylinders.Besides,with the same spacing ratio,the calculated drag coefficient and lift coefficient fluctuation are slightly larger than the 2-D results,but with a phase difference.展开更多
An adaptive tensor voting algorithm combined with texture spectrum is proposed. The image texture spectrum is used to get the adaptive scale parameter of voting field. Then the texture information modifies both the at...An adaptive tensor voting algorithm combined with texture spectrum is proposed. The image texture spectrum is used to get the adaptive scale parameter of voting field. Then the texture information modifies both the attenuation coefficient and the attenuation field so that we can use this algorithm to create more significant and correct structures in the original image according to the human visual perception. At the same time, the proposed method can improve the edge extraction quality, which includes decreasing the flocculent region efficiently and making image clear. In the experiment for extracting pavement cracks, the original pavement image is processed by the proposed method which is combined with the significant curve feature threshold procedure, and the resulted image displays the faint crack signals submerged in the complicated background efficiently and clearly.展开更多
An approach to the simultaneous optical ring resonators is proposed measurement of refractive-index （RI） and theoretically demonstrated. With and temperature changes using a liquid-core silica ring resonator as an e...An approach to the simultaneous optical ring resonators is proposed measurement of refractive-index （RI） and theoretically demonstrated. With and temperature changes using a liquid-core silica ring resonator as an example, two different-order whispering gallery modes （WGMs） might differ in not only RI but also temperature sensitivities. Thus, a second-order sensing matrix should be defined based on these WGMs to determine RI and temperature changes simultaneously. The analysis shows that the RI and temperature detection limits can be achieved on the order of 10.7 RI unit and 10-3 K at a wavelength of approximately 780 nm.展开更多
In this paper,the dynamic characteristics of the cylindrical bubbles under triple-frequency acoustic excitation are investigated theoretically.The analytical solution of the primary-superharmonic-subharmonic(PRI-SUPER...In this paper,the dynamic characteristics of the cylindrical bubbles under triple-frequency acoustic excitation are investigated theoretically.The analytical solution of the primary-superharmonic-subharmonic(PRI-SUPER-SUB)simultaneous resonance is obtained through the multi-scale method.Based on the analysis of the frequency response,the influencing mechanisms of the primary parameters(e.g.,the total amplitude,amplitude ratio,liquid viscosity,polytropic exponent,and bubble equilibrium radius)on the resonance are investigated quantitatively.The main conclusions include:(1)The solution for the simultaneous resonance of the cylindrical bubble exhibits jumping and hysteresis phenomena in the vicinity of the resonance frequency.(2)As the total amplitude,amplitude ratio,and equilibrium radius increase,the response amplitude of the PRI-SUPER-SUB simultaneous resonance increases,while the influence of the viscosity is the opposite.(3)The regions dominated by the instability of the simultaneous resonance is significantly affected by the system parameters.展开更多
Photothermal/photoacoustic（PT/PA） spectroscopy provides useful knowledge about optical absorption, as well as the thermal and acoustical properties of a liquid sample. For microfluidic biosensing and bioanalysis whe...Photothermal/photoacoustic（PT/PA） spectroscopy provides useful knowledge about optical absorption, as well as the thermal and acoustical properties of a liquid sample. For microfluidic biosensing and bioanalysis where an extremely small volume of liquid sample is encapsulated, simultaneous PT/PA detection remains a challenge. In this work, we present a new optofluidic device based on a liquid-core optical ring resonator（LCORR） for the investigation of PT and PA effects in fluid samples. A focused 532 nm pulsed light optically heats the absorptive fluid in a capillary to locally create a transient temperature rise, as well as acoustic waves. A1550 nm CW laser light is quadrature-locked to detect the resonance spectrum shift of the LCORR and study thermal diffusion and acoustic wave propagation in the capillary. This modality provides an optofluidic investigative platform for biological/biochemical sensing and spectroscopy.展开更多
基金National Natural Science Foundation of China under Grant Nos.12172321 and 11472239Hebei Provincial Natural Science Foundation of China under Grant No.A2020203007Hebei Provincial Graduate Innovation Foundation of China under Grant No.CXZZBS2022146。
文摘In this paper,the simultaneous resonance of a ferromagnetic thin plate in a time-varying magnetic field,having axial speed and being subjected to a periodic line load,is studied.Based on the large deflection theory of thin plates and electromagnetic field theory,the nonlinear vibration differential equation of the plate is obtained by using the Hamilton′s principle and the Galerkin method.Then the boundary condition in which the longer opposite sides are clamped and hinged is considered.The dimensionless nonlinear differential equations are solved by using the method of multiple scales,and the analytical solution is given.In addition,the stability analysis is also carried out by using Lyapunov stability theory.Through numerical analysis,the variation curves of system resonance amplitude with frequency tuning parameter,magnetic field strength and external excitation amplitude are obtained.Different parameters that have significant effects on the response of the system,such as the thickness,the axial velocity,the magnetic field intensity,the position,and the frequency of external excitation,are considered and analyzed.The results show that the system has multiple solution regions and obvious nonlinear coupled characteristics.
基金supported by the Open Research Subject of Key Laboratory of Fluid and Power Machinery,Ministry of Education,Xihua University(Grant No.LTDL-2024009).
文摘In the present paper,the simultaneous resonance of a cylindrical bubble under triple-frequency acoustic excitation is investigated theoretically.Specifically,based on the multi-scale method,the dimensionless oscillation equations and the second-order analytical solutions of the primary-subharmonic-subharmonic(PRI-SUB-SUB),primary-superharmonic-superharmonic(PRI-SUPER-SUPER)simultaneous resonances are obtained.Based on the analysis of the frequency response,the nonlinear dynamic behavior of the cylindrical bubble and its influencing factors are analyzed.The primary conclusions include:(1)Under triple-frequency acoustic excitation,the frequency response of PRI-SUB-SUB presents a single peak,and that of PRI-SUPER-SUPER presents two peaks.(2)The polytropic exponent affects both the peak value and position of the resonance peak in the frequency response.(3)The unstable region in frequency response curve of the simultaneous resonance is significantly affected by the total amplitude and equilibrium radius,presenting a positive correlation.
基金supported by the National Natural Science Foundation of China(Grant No.11502050 and No.12272091).
文摘In this study,analytical and numerical methods are applied to investigate the dynamic response of an axially moving plate subjected to parametric and forced excitation.Based on the classical thin plate theory,the governing equation of the plate coupled with fluid is established and further discretized through the Galerkin method.These equations are solved using the method of multiple scales to obtain amplitude-frequency curves and phase-frequency curves.The stability of steady-state response is examined using Lyapunov’s stability theory.In addition,numerical analysis is employed to validate the results of analytical solutions based on the Runge-Kutta method.The multi-value and stability of periodic solutions are verified through stable periodic orbits.Detailed parametric studies show that proper selection of system parameters enables the system to stay in primary resonance or simultaneous resonance,and the state of the system can switch among different periodic motions,contributing to the optimization of fluid-structure interaction system.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50538020)
文摘In the present paper,two-and three-dimensional numerical simulations of the flow interference between four cylinders in an in-line square arrangement at Re = 200 are performed.Assisted with the two-dimensional(2-D) numerical simulation,the mean and fluctuating forces,Strouhal number(St) and vortex shedding pattern in the wake for each cylinder were analyzed with the spacing ratio(L /D) ranging from 1.5 to 6.0.It was found that,four different vortex modes(viz.,flip-flopping,shielding anti-phase-synchronized,in-phasesynchronized and anti-phase-synchronized) gradually appear with the increase of the L/D ratio.The average drag coefficient of the upstream cylinders is larger than that of the downstream cylinders,while the downstream cylinders usually undergo serious fluctuating forces.When the L/D ratio ranges from 3.0 to 4.0,the dominant frequency of the drag coefficient is equal to the value of St of upstream cylinders.This indicates that a simultaneous resonance in the in-flow and cross-flow directions may occur for some single structures of a multi-body oscillating system.For the 3-D numerical simulation,the L/D and aspect ratios are kept constant as 5.0 and 10,respectively.It was found that some vortices are formed in the wake of the upstream cylinders.Besides,with the same spacing ratio,the calculated drag coefficient and lift coefficient fluctuation are slightly larger than the 2-D results,but with a phase difference.
基金supported by the National Natural Science Foundation of China(No.61471185)the Joint Special Fund of Shandong Province Natural Science Foundation(No.ZR2013FL008)the Project of Shandong Province Higher Educational Science and Technology Program(No.J14LN20)
文摘An adaptive tensor voting algorithm combined with texture spectrum is proposed. The image texture spectrum is used to get the adaptive scale parameter of voting field. Then the texture information modifies both the attenuation coefficient and the attenuation field so that we can use this algorithm to create more significant and correct structures in the original image according to the human visual perception. At the same time, the proposed method can improve the edge extraction quality, which includes decreasing the flocculent region efficiently and making image clear. In the experiment for extracting pavement cracks, the original pavement image is processed by the proposed method which is combined with the significant curve feature threshold procedure, and the resulted image displays the faint crack signals submerged in the complicated background efficiently and clearly.
基金supported by the National "973" Program of China (No. 2011CB013000)the National Natural Science Foundation of China (Nos. 90923039and 51025521)
文摘An approach to the simultaneous optical ring resonators is proposed measurement of refractive-index （RI） and theoretically demonstrated. With and temperature changes using a liquid-core silica ring resonator as an example, two different-order whispering gallery modes （WGMs） might differ in not only RI but also temperature sensitivities. Thus, a second-order sensing matrix should be defined based on these WGMs to determine RI and temperature changes simultaneously. The analysis shows that the RI and temperature detection limits can be achieved on the order of 10.7 RI unit and 10-3 K at a wavelength of approximately 780 nm.
基金supported by the National Natural Science Foundation of China(Grant No.51976056).
文摘In this paper,the dynamic characteristics of the cylindrical bubbles under triple-frequency acoustic excitation are investigated theoretically.The analytical solution of the primary-superharmonic-subharmonic(PRI-SUPER-SUB)simultaneous resonance is obtained through the multi-scale method.Based on the analysis of the frequency response,the influencing mechanisms of the primary parameters(e.g.,the total amplitude,amplitude ratio,liquid viscosity,polytropic exponent,and bubble equilibrium radius)on the resonance are investigated quantitatively.The main conclusions include:(1)The solution for the simultaneous resonance of the cylindrical bubble exhibits jumping and hysteresis phenomena in the vicinity of the resonance frequency.(2)As the total amplitude,amplitude ratio,and equilibrium radius increase,the response amplitude of the PRI-SUPER-SUB simultaneous resonance increases,while the influence of the viscosity is the opposite.(3)The regions dominated by the instability of the simultaneous resonance is significantly affected by the system parameters.
基金supported by the National Natural Science Foundation of China(No.11374129)the Planned Science&Technology Project of Guangzhou(No.2014J2200003)
文摘Photothermal/photoacoustic（PT/PA） spectroscopy provides useful knowledge about optical absorption, as well as the thermal and acoustical properties of a liquid sample. For microfluidic biosensing and bioanalysis where an extremely small volume of liquid sample is encapsulated, simultaneous PT/PA detection remains a challenge. In this work, we present a new optofluidic device based on a liquid-core optical ring resonator（LCORR） for the investigation of PT and PA effects in fluid samples. A focused 532 nm pulsed light optically heats the absorptive fluid in a capillary to locally create a transient temperature rise, as well as acoustic waves. A1550 nm CW laser light is quadrature-locked to detect the resonance spectrum shift of the LCORR and study thermal diffusion and acoustic wave propagation in the capillary. This modality provides an optofluidic investigative platform for biological/biochemical sensing and spectroscopy.
