A Novel Method for Pavement Transverse Crack Detection Based on 2D Reconstruction of Vehicle Vibration Signal

Wenzhi Yuan,Qun Yang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Pavement transverse cracks are associated with pavement performance. However, due to lowrecognition accuracy, the transverse cracking detection through vehicle’s vibration responsehas hardly been considered. This paper proposes a novel method for pavement transversecracking detection using reconstructed vehicle vibration signal. An accelerometer installed inthe vehicle collects the vibration response between the vehicle and the pavement transversecracks. A brand-new approach to data processing is suggested that transforms a onedimensionalvibration signal into a two-dimensional vibration image. The two-dimensionalvibration image generated can obtain different features effectively from the time domain. Based on Gray Level Concurrence Matrix (GLCM) algorithm, a characteristic index establishedfrom the vibration image’s contrast can distinguish transverse cracks from uncracked sections. Then its feasibility was investigated by 410 pavement sections, the accuracy of the index is93.84%. The transverse crack detection method proposed in this paper seems promising forprecisely identifying pavement transverse cracks.

Elimination of Overshoot and Oscillation in the Auxiliary Branch of a SiC Auxiliary Resonant Commutated Pole Inverter (ARCPI)

Wenzhi Zhou,Xibo Yuan,Ian Laird 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper investigates the mechanism of the overshoot and oscillation in the auxiliary branch and its elimination in a silicon carbide (SiC) auxiliary resonant commutated pole inverter (ARCPI). A mathematical model of the auxiliary branch including the parasitic capacitance of SiC MOSFETs has been derived, which reveals the oscillation mechanism in the auxiliary branch. The model shows that this oscillation is an inherent characteristic of the SiC ARCPI. To eliminate the overshoot and oscillation, a SiC ARCPI with two clamping diodes inserted between the DC bus and the auxiliary branch has been presented. The proposed auxiliary branch oscillation model and the performance of the clamped ARCPI are validated on a 3-kW, 3-phase SiC ARCPI prototype. Even though the overshoot and oscillation in the auxiliary branch has an insignificant impact on the output voltage, experimental results show that without clamping, the overshoot is more than 150% and the oscillation frequency is higher than 4 MHz. This significantly increases the required voltage ratings of the devices in the auxiliary branch. Furthermore, the overshoot and oscillation frequency in the auxiliary branch increases with the DC bus voltage because the output capacitance of the SiC MOSFETs reduces with the voltage. This degrade the electromagnetic interference (EMI) performance of the SiC ARCPI. In comparison, the clamped SiC ARCPI can mitigate the overshoot and oscillation and improve the EMI performance of the auxiliary branch. Specifically, around 6 MHz the spectral amplitude can be reduced by about 17% by the clamped ARCPI.

An Active Voltage Doubling Rectifier with Unbalanced-Biased Comparators for Piezoelectric Energy Harvesters

Lianxi Liu,Junchao Mu,Wenzhi Yuan,Wei Tu,Zhangming Zhu,Yintang Yang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 ㎟, while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.

Seroprevalence of Dirofilaria immitis in Cats from Liaoning Province, Northeastern China

Honglie Hou,Lili Cao,Wenzhi Ren,Dansheng Wang,He Ding,Juan You,Xinhua Yao,Hang Dong,Yanbing Guo,Shuxian Yuan,Xi-Chen Zhang,Pengtao Gong 대한기생충학ㆍ열대의학회 2017 The Korean Journal of Parasitology Vol.55 No.6

The present study was performed to investigate the seroprevalence and risk factors for Dirofilaria immitis infection in cats from Liaoning province, northeastern China. From October 2014 to September 2016, sera of 651 cats, including 364 domestic cats and 287 feral cats (332 females and 319 males) were assessed. They were tested for the presence of D. immitis antigen using SNAP Heartworm RT test kit. In this population, the average prevalence was 4.5%. Age and rearing conditions (feral or domestic) were found to be associated with the prevalence of D. immitis. The prevalence was significantly higher in feral cats compared with domestic cats (8.4% vs 1.4%, P<0.01). There was no significant difference between males and females (4.7% vs 4.2%, P>0.05), but older cats (≥3 years old) showed a statistically higher prevalence compared with younger cats (<3 years old) in feral populations (16.8 vs 2.4%, P<0.01), while the difference between the age groups was not statistically significant in domestic cats (2.4% vs 0.51%, P>0.05), all these results suggest that outdoor exposure time may be one of the most important factors for D. immitis prevalence in cats. Results reveal that D. immitis are prevalence in domestic and feral cats in northeastern China, which indicates that appropriate preventive measures should be taken to decrease the incidence of feline heartworm disease in Liaoning province, northeastern China.

An Active Voltage Doubling Rectifier with Unbalanced-Biased Comparators for Piezoelectric Energy Harvesters

Liu, Lianxi,Mu, Junchao,Yuan, Wenzhi,Tu, Wei,Zhu, Zhangming,Yang, Yintang The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 mm², while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.