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Jiayu Xu,Rongxiang Tian,Song Feng 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.4
Vertical motion is an important feature of the atmosphere, being closely linked to clouds and precipitation. Here, we present a comparison of the vertical velocity of air over China, with particular focus on the Tibetan Plateau, during the period 1981–2010 using three reanalysis datasets: ERA-Interim, JRA-55 and NCEP/NCAR. Analysis methods including empirical orthogonal functions analysis and correlation analysis were used to examine consistency between the datasets and their suitability in research and application in China. Our results show that the vertical velocity fields from ERA-Interim and JRA-55 are more consistent than they are with those from NCEP/NCAR. The atmospheric vertical velocity fields from NCEP/NCAR lack details compared with those obtained from ERA-Interim and JRA-55, and part of values for the upper troposphere over the ocean south of 15°N are contrary to the other datasets and the climatic reality. Therefore, use of ERA-Interim or JRA-55 may be preferable over NCEP/NCAR. The intensity of atmospheric vertical motion in the lower troposphere in JRA-55 is significantly higher than in ERA-Interim and NCEP/NCAR. In summer, the JRA-55 data are closest to the observed wind fields and the data stability best for the Tibetan Plateau region. Our results provide guidance for better application of reanalysis data and more accurate climate prediction for this region.
Zhi-jie Liang,Jiayu Peng,Jiale Liang,Yujing Song,Weini Jia,Qing-hui Mao 한국섬유공학회 2022 Fibers and polymers Vol.23 No.12
The outstanding redox chemistry of polyoxovanadate has shown excellent catalysis prospects. In the present work,the effect of polyoxovanadate (K7[MnV13O38]·18H2O) on the catalytic polymerization of catechol was investigated for thefirst time. The synthesized polymer was applied in-situ for the dyeing of cotton under mild conditions. Various processparameters, including the dosages of catechol and polyoxovanadate and incubation temperature, which influence the colordepth, were analyzed. The effect of different time intervals on polyoxovanadate-catalyzed polymerization of catechol wasexamined using UV-vis spectroscopy. The color intensity of cotton was evaluated by means of K/S value and color difference(ΔE*). The results show that the dyeing depth of the dyed cotton fabrics gradually increased with the extension of time andthe increase in the concentration of polyoxovanadate. This work represents a novel synthetic process exploring the potentialof a polymer to be used for textile dyeing.
Sensorless Control of the Switched Reluctance Motor Based on the Sliding-Mode Observer
Li Xinyu,Liu Jiayu,Ge Lefei,Zhong Jixi,Huang Jiale,Zhao Yuchen,Song Shoujun 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2
To upgrade the application of switched reluctance motors (SRMs) for more electric aircraft, this paper presents a method with sensorless control based on the flux-linkage data from the finite element method. First, a calibration strategy is employed to obtain the flux-linkage characteristics. Then, a sliding-mode observer is used to realize the sensorless control of the SRM. The proposed method only requires the flux-linkage of the SRM at aligned and unaligned rotor positions from the experiment which takes a low-measurement effort to get the rotor position and has better accuracy in position and speed estimation than the FEM. Experimental results verify the accuracy and effectiveness of the proposed method.
Effects of Influencing Factors on a Lab-Scale Device for Dynamic Scaling Mitigation
Tao Yu,Ying Wang,Jiayu Song,Baichun Wu,Xin Zhang,Chengtun Qu 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6
To investigate the dynamic scaling properties of produced water from oil and gas fields, in this study, an experimental dynamic scaling mitigation device consisting of a filler cylinder, a sewage circulation device, and a heating device was designed. The effects of important factors, namely, initial concentration of scale-forming ions, contact time, temperature, and flow rate, on the dynamic scaling process were investigated using this device. The results obtained showed that the rate of scale adsorption on cotton fiber decreased gradually as the initial concentration of the scale-forming ions increased, and the scale adsorption rate peaked at 97.5% when the contact time was between 2 and 8 h. It was also observed that the maximum scale adsorption rate and amount corresponded to experimental temperatures of 50 and 40°C, respectively. Furthermore, the maximum scale adsorption rate was 94% at a flow rate of 60 L/h, while the scale adsorption amount peaked at a flow rate of 100 L/h. These results provide important guidelines for the establishment of a rapid measurement method for dynamic scaling in produced water from oil and gas fields and for the evaluation of water quality stability for water flooding extraction.
Hehan Tang,Na Hu,Yuan Yuan,Chunchao Xia,Xiumin Liu,Panli Zuo,Aurelien F. Stalder,Michaela Schmidt,Xiaoyue Zhou,Bin Song,Jiayu Sun 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.2
Objective: To compare the image quality of three-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) with sparse undersampling and iterative reconstruction (sparse TOF) with that of conventional TOF MRA. Materials and Methods: This study included 56 patients who had undergone sparse TOF MRA for intracranial artery evaluation on a 3T MR scanner. Conventional TOF MRA scans were also acquired from 29 patients with matched acquisition times and another 27 patients with matched scanning parameters. The image quality was scored using a five-point scale based on the delineation of arterial vessel segments, artifacts, overall vessel visualization, and overall image quality by two radiologists independently, and the data were analyzed using the non-parametric Wilcoxon signed-rank test. Contrast ratios (CRs) of vessels were compared using the paired t test. Interobserver agreement was calculated using the kappa test. Results: Compared with conventional TOF at the same spatial resolution, sparse TOF with an acceleration factor of 3.5 could reduce acquisition time by 40% and showed comparable image quality. In addition, when compared with conventional TOF with the same acquisition time, sparse TOF with an acceleration factor of 5 could also achieve higher spatial resolution, better delineation of vessel segments, fewer artifacts, higher image quality, and a higher CR (p < 0.05). Good-to-excellent interobserver agreement (к: 0.65–1.00) was obtained between the two radiologists. Conclusion: Compared with conventional TOF, sparse TOF can achieve equivalent image quality in a reduced duration. Furthermore, using the same acquisition time, sparse TOF could improve the delineation of vessels and decrease image artifacts.