A new method of calculating fractal dimension of short-term heart rate variability signals is presented. The method is based on wavelet transform and filter banks. The implementation of the method is: First of all we pick-up the fractal component from HRV signals using wavelet transform. Next, we estimate the power spectrum distribution of fractal component using auto-regressive model, and we estimate parameter 7 using the least square method. Finally according to formula D = 2- (gamma-1)/2 estimate fractal dimension of HRV signal. To validate the stability and reliability of the proposed method, using fractional brown movement simulate 24 fractal signals that fractal value is 1.6 to validate, the result shows that the method has stability and reliability.
Algorithms ; Electrocardiography ; Fourier Analysis ; Fractals ; Heart Rate ; physiology ; Humans ; Least-Squares Analysis ; Nonlinear Dynamics ; Signal Processing, Computer-Assisted

Objective To find a method for denoising of ECG signals during spaceflight.Method According to noise character of ECG during spaceflight,a new denoising method that combines wavelet transform and shape filter was put forward.Result By practical application and simulation test,it was proved that this method could eliminate efficiently noise from ECG during spaceflight.Conclusion The method that combines wavelet transform and shape filter can be used for ECG denoising during spaceflight.

Purpose To investigate the multi-slice spiral CT (MSCT) features ofchromophobe renal cell carcinoma (CCRC),renal oncocytoma (RO) and clear-cell renal cell carcinoma (CCRCC) for the improvement of its diagnostic accuracy.Materials and Methods The MSCT data of 15 CCRC cases,8 RO cases,and 29 CCRCC cases confirmed by surgery or pathology at Dong H ua Hospital from October 2012 to April 2016 were retrospectively studied.The CT signs of different tumors were compared.Results Most CCRCC cases had cystic degenerations,which showed significant difference with CCRC and RO cases (P＜0.05);RO cases were found mostly with star-shaped scars,which had significant difference with CCRCC cases (P＜0.05);the enhanced scanning showed most of CCRC were enhanced homogeneously,which presented significant difference from CCRCC (P＜0.05).The lesion-kidney-ration (LKR) of CCRCC at cortical phase,parenchymal phase or excretory phase was significantly different from that of CCRC (P＜0.05);the LKR of CCRCC at cortical phase was significantly different from that of RO (P＜0.05);the LKR of CCRC at the three phases were all significantly different from that of RO (P＜0.05).The average △ LKR value of CCRCC was significantly different from that of CCRC and RO (P＜0.05);there was a certain degree of difference distribution of their △ LKR among the three kinds of cases.Taking CCRCC as object,when the LKR at cortical phase was 0.693 or △ LKR was 0.068,the sensitivity reached 93.3％ and the specificity reached 72.2％ or 88.9％ respectively in evaluating the differential diagnosis of CCRC and RO.Taking RO as object,when the LKR was 0.656 at cortical phase or was 0.595 at parenchymal phase,the sensitivity reached 83.3％ and 91.7％ respectively,and the specificity was 75.0％ and 58.3％ respectively,in evaluating the differential diagnosis of CCRC.Conclusion Enhanced MSCT at different phases,especially the calculation of LKR and △ LKR value,can benefit the diagnosis of CCRC,RO and CCRCC.