The purpose of this study is to establish the simulation model of the gas emboli by analyzing reasons for features of gas emboli Doppler ultrasound signals. It is useful for the further classification of the solid emb...The purpose of this study is to establish the simulation model of the gas emboli by analyzing reasons for features of gas emboli Doppler ultrasound signals. It is useful for the further classification of the solid emboli and gas emboli. First, the model of the radiation force and the drag force is used to calculate forces acting on the gas emboli. Second, the acceleration of the gas emboli is calculated in both the radial direction and the axial direction of the vessel, which is used to calculate the trajectory of the gas emboli in the vessel. Finally, the computer simulation model is established for the gas emboli. Doppler ultrasound signals of the gas emboli and the solid emboli are generated in the simulation experiment. Experimental results show that compared with the solid emboli, the gas emboli acted by the radiation force and the drag force will result in the frequency-domain broaden in the Doppler spectrogram. When the gas emboli circulate from the low speed area to the high speed one and then from the high speed area back to the low speed one, a ＂V＂ shape will be shown in the spectrogram of gas emboli signals. When the gas emboli circulate from the low speed area to the high speed one or from the high speed area to the low speed one, a diagonal shape will be shown for gas emboli signals. It is also shown that features of simulated gas emboli signals match with those of gas emboli signals sampled from clinic. All demonstrate that the simulation method of the gas emboli is reasonable.展开更多
A computer simulation method for pulsed Doppler signals from vortices was pro- posed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequenc...A computer simulation method for pulsed Doppler signals from vortices was pro- posed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequency waveform, the mean frequency waveform and the bandwidth waveform, were obtained using the short time Fourier analysis of those simulated signals. The relations were studied between several spectrum parameters obtained from these waveforms and given simulation conditions, such as the position and the size of the sample volume, the distance between two vortices, the free stream velocity and the maximum tangent velocity of the vortex. The sensitive parameters were found to detect vortices using the pulsed Doppler techniques.展开更多
基金supported by the Natural Science Foundation of China(10974035)the Program of Shanghai Subject Chief Scientist(10XD1400600)
文摘The purpose of this study is to establish the simulation model of the gas emboli by analyzing reasons for features of gas emboli Doppler ultrasound signals. It is useful for the further classification of the solid emboli and gas emboli. First, the model of the radiation force and the drag force is used to calculate forces acting on the gas emboli. Second, the acceleration of the gas emboli is calculated in both the radial direction and the axial direction of the vessel, which is used to calculate the trajectory of the gas emboli in the vessel. Finally, the computer simulation model is established for the gas emboli. Doppler ultrasound signals of the gas emboli and the solid emboli are generated in the simulation experiment. Experimental results show that compared with the solid emboli, the gas emboli acted by the radiation force and the drag force will result in the frequency-domain broaden in the Doppler spectrogram. When the gas emboli circulate from the low speed area to the high speed one and then from the high speed area back to the low speed one, a ＂V＂ shape will be shown in the spectrogram of gas emboli signals. When the gas emboli circulate from the low speed area to the high speed one or from the high speed area to the low speed one, a diagonal shape will be shown for gas emboli signals. It is also shown that features of simulated gas emboli signals match with those of gas emboli signals sampled from clinic. All demonstrate that the simulation method of the gas emboli is reasonable.
基金This work is supported by the Outstanding Young Teacher Funds of Chinese Ministry of Education.
文摘A computer simulation method for pulsed Doppler signals from vortices was pro- posed to generate simulated vortex Doppler signals under various given circumstances. The relative waveforms, such as the maximum frequency waveform, the mean frequency waveform and the bandwidth waveform, were obtained using the short time Fourier analysis of those simulated signals. The relations were studied between several spectrum parameters obtained from these waveforms and given simulation conditions, such as the position and the size of the sample volume, the distance between two vortices, the free stream velocity and the maximum tangent velocity of the vortex. The sensitive parameters were found to detect vortices using the pulsed Doppler techniques.
