| 1 | Space charge dynamics in epoxy resin under voltage polarity reversal at various temperatures显示文摘Epoxy resin has been used to cast the core of the dry‐type high voltage direct current bushings and can accumulate space charge under high electric fields at high temperatures,which is believed to be a potential threat to the safe operation of dry bushings,especially under polarity reversal.In this study,results of a study of the evolution of space charge and electric field distribution in epoxy resin,under polarity reversal at 10 and 20 kV/mm,and at temperatures between 40 and 100°C,are presented.The results show that the space charge dynamics in epoxy resin during the test were different at various temperatures.At tem-peratures no more than 60°C,space charge accumulation within the samples was not obvious.Instead,a low‐frequency dielectric relaxation process maybe occurs during the polarity reversal,which made the charge peaks on the electrodes after the reversal were slightly smaller than those before the reversal.At temperatures no less than 80°C,considering that the applied electric field has little effect on the barrier reductions of the traps within the samples,the space charge dynamics were mainly governed by a thermally activated process,and the depths of the deepest occupied traps were obtain by analysing the transient processes. | Peng Liu Hongliang Zhang Siyu Zhang Xialin Su Zongliang Xie Zongren Peng | 2021 | High Voltage2021，6，5： | 1 |
| 2 | Study on Variation of Endogenous Hormones at the Germinating Stage of Tea Spring Shoot显示文摘An HPLC method was used to analyze the contents ana variation of IAA, GA3, ABA and ZT at five stages around the tea shoot germinating in spring. The contents of GA3 and ABA had a top value during the winter and decreased with the growth of tea shoots, while the contents of IAA and ZT had a low value during the winter and increased quickly at the beginning of shoot growth, but soon afterwards increased slowly or decreased a little. The ratio of hormones was closely related to the growth of tea plant. The study indicated that the ratios of GA3 to ABA and IAA to ABA were at low values during the winter and went up with the shoot germinating. When the activity of roots was weak, the ratio of ZT to IAA had a top value, but went down gradually with luxuriant activity of roots. The ratio of GA3 to ZT had a certin relativity with the shoot germinating, which was at a top value during the winter but went down suddenly at the beginning of shoot germinating. | Huang Yahui,Su Benwen,Zeng Zhen,Liu Xialin,and Zheng Hongfa Hunan Tea Research Institute,Changsha,Hunan 410125 | 2001 | Hunan Agricultural Science & Technology Newsletter2001，2，1： | 0 |
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