The mixed noise in the acquisition process of pulse wave signals will affect the signal analysis, how to effectively eliminate the noise and complete the pulse wave analysis has important practical significance. In th...The mixed noise in the acquisition process of pulse wave signals will affect the signal analysis, how to effectively eliminate the noise and complete the pulse wave analysis has important practical significance. In this paper, empirical mode decomposition(EMD) and ensemble empirical mode decomposition(EEMD) were used to realize scale decomposition of pulse wave signals to obtain intrinsic mode function(IMF). A band-pass filter was implemented according to the characteristic time scale parameters of the IMF. After filtering and reconstruction, the pulse wave denoising was completed. The denoising effects of EMD, EEMD and wavelet transform were compared in terms of mean square error and signal-to-noise ratio. The result shows that EMD and EEMD are better than wavelet transform, and the effects are similar. Further comparing the Hilbert-Huang spectrum of EMD and EEMD, it can be seen that EEMD can not only avoid mode mixing, but also facilitate the analysis of pulse wave signals.展开更多
. In this paper, an approach to the design of hemispherical breast RF coil array is proposed. The target field method is applied to find the current density distribution on the hemisphere surface, which induces a homo.... In this paper, an approach to the design of hemispherical breast RF coil array is proposed. The target field method is applied to find the current density distribution on the hemisphere surface, which induces a homogeneous magnetic field in a hemispherical volume. The components of current density are expanded into Fourier series, and the highly ill-conditioned character of the linear equation related to Fourier coefficients is solved using the Tikhonov regularization method with a minimum curvature penalty function. The winding pattern was acquired using the stream function technique. The results indicate that a simple winding pattern with homogeneous magnetic field can be obtained through manually selecting the penalty factor.展开更多
Atrial fibrillation(AF)is a common cardiac rhythm disturbance that increases in prevalence with advancing age.To get the real time location of the related key lesions is of great significance to treat and abolish AF.T...Atrial fibrillation(AF)is a common cardiac rhythm disturbance that increases in prevalence with advancing age.To get the real time location of the related key lesions is of great significance to treat and abolish AF.Two-dimensional finite element method was adopted to simulate the lead field.Based on the acoustoelectric effect and the reciprocal theory,the source density of the current field was calculated,thus determining the precise location of the current source and sink.Results show that the simulated positioning precision of current source and sink is within submillimetre only using a pair of recording electrode.This work implies that it is promising to locate the key lesions from messy fibrillation using the acoustoelectric effect method.展开更多
文摘The mixed noise in the acquisition process of pulse wave signals will affect the signal analysis, how to effectively eliminate the noise and complete the pulse wave analysis has important practical significance. In this paper, empirical mode decomposition(EMD) and ensemble empirical mode decomposition(EEMD) were used to realize scale decomposition of pulse wave signals to obtain intrinsic mode function(IMF). A band-pass filter was implemented according to the characteristic time scale parameters of the IMF. After filtering and reconstruction, the pulse wave denoising was completed. The denoising effects of EMD, EEMD and wavelet transform were compared in terms of mean square error and signal-to-noise ratio. The result shows that EMD and EEMD are better than wavelet transform, and the effects are similar. Further comparing the Hilbert-Huang spectrum of EMD and EEMD, it can be seen that EEMD can not only avoid mode mixing, but also facilitate the analysis of pulse wave signals.
文摘. In this paper, an approach to the design of hemispherical breast RF coil array is proposed. The target field method is applied to find the current density distribution on the hemisphere surface, which induces a homogeneous magnetic field in a hemispherical volume. The components of current density are expanded into Fourier series, and the highly ill-conditioned character of the linear equation related to Fourier coefficients is solved using the Tikhonov regularization method with a minimum curvature penalty function. The winding pattern was acquired using the stream function technique. The results indicate that a simple winding pattern with homogeneous magnetic field can be obtained through manually selecting the penalty factor.
基金Science Technology Department Program of Zhejiang Provincegrant number:2014C37074
文摘Atrial fibrillation(AF)is a common cardiac rhythm disturbance that increases in prevalence with advancing age.To get the real time location of the related key lesions is of great significance to treat and abolish AF.Two-dimensional finite element method was adopted to simulate the lead field.Based on the acoustoelectric effect and the reciprocal theory,the source density of the current field was calculated,thus determining the precise location of the current source and sink.Results show that the simulated positioning precision of current source and sink is within submillimetre only using a pair of recording electrode.This work implies that it is promising to locate the key lesions from messy fibrillation using the acoustoelectric effect method.
