PubMed Health⌕ Search

Biomedical subjects

Zhi-zhong Wang

Publications and source records attributed to Zhi-zhong Wang.

6 recordsLinked to original sources
PubMed2006

Characterization of surface EMG signals using improved approximate entropy.

An improved approximate entropy (ApEn) is presented and applied to characterize surface electromyography (sEMG) signals. In most previous experiments using nonlinear dynamic analysis, this certain processing was often confronted with the problem of insufficient data points and noisy circumstances, which led to unsatisfactory results. Compared with fractal dimension as well as the standard ApEn, the improved ApEn can extract information underlying sEMG signals more efficiently and accurately. The method introduced here can also be applied to other medium-sized and noisy physiological signals.

Algorithms↗
PubMed2005

Classification of surface EMG signal with fractal dimension.

Surface EMG (electromyography) signal is a complex nonlinear signal with low signal to noise ratio (SNR). This paper is aimed at identifying different patterns of surface EMG signals according to fractal dimension. Two patterns of surface EMG signals are respectively acquired from the right forearm flexor of 30 healthy volunteers during right forearm supination (FS) or forearm pronation (FP). After the high frequency noise is filtered from surface EMG signal by a low-pass filter, fractal dimension is calculated from the filtered surface EMG signal. The results showed that the fractal dimensions of filtered FS surface EMG signals and those of filtered FP surface EMG signals distribute in two different regions, so the fractal dimensions can represent different patterns of surface EMG signals.

Algorithms↗
PubMed2005

[The application of BP neural network improved with LM algorithm in surface EMG signal classification].

The method of BP neural network improved by Levenberg-Marquardt algorithm in surface EMG signal classification is proposed. The data reduction and preprocessing operations of the signals are performed by means of the wavelet transform. The classifier can identify four classes of forearm movement: hand extension, hand grasp,forearm pronation and forearm supination with a high accuracy.Experimental result shows that the BP neural netwok improved by LM algorithm has greatly increased the speed and the accuracy of signal classification in practical application of prothesis control.

Algorithms↗
PubMed2004

[Experimental study of the effects of mild hypothermia on the acute myocardial infarction size in the rabbits with coronary artery reperfusion].

OBJECTIVE: To study the effect of mild hypothermia on the acute myocardial infarction size in the rabbits with coronary artery reperfusion. METHODS: fourteen rabbits were randomly divided into two groups: mild hypothermia group and control group. Each group underwent 45 minutes of left anterior descending coronary artery occlusion and 2 hours of reperfusion. Core temperatures were measured with thermistor. The mild hypothermia group received ice cooling around the body and the core temperature was dropped to 32-35 centigrade after occluded for 30 minutes, while the control group's body temperature were kept above 38 centigrade. The myocardial area at risk and the infarct area were determined with Evan's blue dye and triphenyl tetrazolium chloride (TTC). RESULTS: The total elevated amplitude of ST segment in chest leads V1, V3 and V5 in the mild hypothermia group was (25.8+/-8.5) mV, it was lower than that in the control group (37.7+/-6.5) Mv (P=0.021). The changes of serum MB isoenzyme of creatine kinase (CK-MB) activities in mild hypothermia group was (2646.9+/-1227.3) U/L, it was significantly lower than that in the control group (4787.8+/-1934.2) U/L(P=0.045). The weight of infarct myocardium of the mild hypothermia group was (0.23+/-0.05)g, it was lower than that in the control group (0.42+/-0.16)g (P=0.020). Myocardial infarct size as a percentage of the risk zone (0.214+/-0.044 vs. 0.357+/-0.066, P=0.001) and of the left ventricle weight (0.041+/-0.010 vs. 0.071+/-0.027, P=0.029) were smaller than those in the control group. The ratio of the survived myocardial area over the risk zone in the mild hypothermia group was significantly higher than that in the control group (0.786+/-0.044 vs. 0.643+/-0.066, P<0.001). CONCLUSION: Mild hypothermia may reduce infarct size in the rabbits with transient acute myocardial infarction, and increase survived myocardium in the risk zone.

Animals↗
PubMed2003

[Implication of cochlear implantation in patients with enlarged vestibular aqueduct syndrome].

OBJECTIVE: To evaluate the intraoperative obstacles and post-operative outcomes of cochlear implantation in children with enlarged vestibular aqueduct syndrome. METHODS: Between May 1995 and June 2002, 10 patients with enlarged vestibular aqueduct syndrome received cochlear implantation in Pekin Union Medical College Hospital. The clinical records of 10 cases of enlarged vestibular aqueduct syndrome were analyzed retrospectively. RESULTS: Via cochleostomy pulsatile clear fluid gusher occurred in 8 cases, which were easily controlled by quickly inserting the electrode array and sealing the cochleostomy with muscle tissue in each instance. The implant was inserted without difficulty in all patients. There have been no post-operatively complications, and audiologic outcome of the 10 patients with cochlear implantation were almost the same as the other patients without inner ear malformations. Five cases of them can even speak better than the other prelingual deafness that may be attributed in part to postlingual deafness. CONCLUSIONS: Despite pulsatile clear fluid gusher in cochlear implantation, no post-operatively complications have been found, and the outcome of these 10 patients with cochlear implantation was excellent. Cochlear implantation can be safely and effectively performed in patients with profound sensorineural hearing loss (SNHL) associated with enlarged vestibular aqueduct syndrome.

Adolescent↗