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The special operation mode of high-speed railway will generate a large amount of harmonics. The harmonics will be transmitted to the 220kV side high-voltage cables through the traction transformer, and harmonic voltages will be generated on the cable sheath, threatening the safe operation of the cables. In this paper, on the basis of the measured harmonic data of the traction substation, a harmonic source model based on the measured data is established, which solves the complex problem of harmonic source modeling and can accurately reflect the actual operating conditions of high-speed trains. On this basis, the harmonic voltage characteristics of the cable sheath on the 220kV side of the high-speed railway under the three working conditions of traction, regenerative braking and inertia are simulated and calculated, and the effects of cable length, cable grounding method, and harmonic current parameters on the harmonic voltage are explored. Affect the law. The results show that under different operation modes of high-speed rail, the harmonic voltage of the sheath far exceeds the normal operation of the power frequency, and the maximum value of the harmonic voltage of the cable sheath can reach 454V under the traction condition; Under working conditions, the overvoltage of the metal sheath is greatly affected by the grounding method of the cable, the length of the cable and the harmonic current content. The above research results have important reference significance for the safe operation of electrified railways.

Background: Vibration response imaging (VRI) is a new technology for lung imaging. Active smokers and non-smokers show differences in VRI findings, but no data are available for passive smokers. The aim of this study was to evaluate the use of VRI and to assess the differences in VRI findings among non-smokers, active smokers, and passive smokers., Material and Methods: Healthy subjects (n=165: 63 non-smokers, 56 active smokers, and 46 passive smokers) with normal lung function were enrolled. Medical history, physical examination, lung function test, and VRI were performed for all subjects. Correlation between smoking index and VRI scores (VRIS) were performed., Results: VRI images showed progressive and regressive stages representing the inspiratory and expiratory phases bilaterally in a vertical and synchronized manner in non-smokers. Vibration energy curves with low expiratory phase and plateau were present in 6.35% and 3.17%, respectively, of healthy non-smokers, 41.07% and 28.60% of smokers, and 39.13% and 30.43% of passive smokers, respectively. The massive energy peak in the non-smokers, smokers, and passive-smokers was 1.77±0.27, 1.57±0.29, and 1.66±0.33, respectively (all P<0.001). A weak but positive correlation was observed between VRIS and smoking index., Conclusions: VRI can intuitively show the differences between non-smokers and smokers. VRI revealed that passive smoking can also harm the lungs. VRI could be used to visually persuade smokers to give up smoking.