Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： The northeast of Qinghai province is the main area of crop production, and also the high-risk area of hail. Hail Forecast, early warning and artificial anti-hail operation are the important means to reduce hail disaster, to master the characteristics of hail monitoring data is the precondition to improve the ability of hail forecast and to carry out hail suppression as early as possible. The hailstorm process on 29 June 2021 at northeast of Qinghai is analyzed by using doppler radar data, raindrop spectrum data, high and ground data. The results show that there is cold advection transportation of upper-level while temperature increases obviously on ground in the northeast of Qinghai, formation of the extreme unstable atmosphere stratification, which is the weather background of this hailstorm process. During the period of hailstorm, the average raindrop spectrum and velocity spectrum are multi-peak distribution at Pingan station. The difference between the maximum diameter of Pingan hailstorm observed artificial and raindrop spectrometer is not large, which indicates that raindrop spectrometer can observe hail particles well and determine the time of maximum hail appears. The development of this hail cloud has roughly gone through the stages of occurrence, jump, hail and extinction. There is an obvious “V” shaped inflow gap in the low-level radar reflectivity factor before hail. In the mature stage, the hail cloud has obvious bounded weak echo area, and there is obvious southerly inflow in the middle and lower layers, at this time, the hail cloud on the radial velocity map has an obvious“0 line”, “0 line” vertical upward, through the overhanging echo and bounded weak echo region, pointing to the hail cloud top. The research results have important guiding significance for hail forecast at northeast of Qinghai, and the characteristics of various elements before hail occurrence are the important criteria for scientific guiding hail suppression operation sites to carry out artificial hail suppression operation timely and appropriately in the later stage.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： Corrosion behavior of E36 and E690 steel in simulated seawater was comparatively studied by means of mass loss method, electrochemical measurements, morphology observation and analysis of corrosion products. The results showed that the two steels exhibited similar electrochemical behavior with characteristics of activation dissolution and very low corrosion current density; the two steels presented a homogeneous corrosion morphology with a low corrosion rate, which declined with time; during the first week immersion the two steels exhibited nearly the same corrosion rate and while the average corrosion rate of E690 gradually fell behind that of E36 after four weeks.
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