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
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.
