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覆冰会改变绝缘子表面的电场分布,影响绝缘子闪络特性,如何得到覆冰条件下绝缘子表面的电场分布对防止绝缘子覆冰闪络具有重要意义。在总结国内外覆冰绝缘子电场分布研究的基础上,对覆冰绝缘子沿面电场测量、覆冰绝缘子沿面电场计算方法的优缺点进行了分析,并指出有限元法、边界元法等数值解法将是今后研究覆冰绝缘子表面电场分布的主要手段。 相似文献
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【题目】某电子只受电场力的作用,在下述哪种电场中,只要电子的初速度分别取得适当的值,电子既可以沿某条电场线运动,也有可能沿某等势面(线)运动(A)匀强电场.(B)孤立正点电荷产生的电场.(C)等量异种电荷产生的电场.(D)等量同种电荷产生的电场.【参考答案】学生在解答此题时,绝 相似文献
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《中学生数理化(高中版)》2011,(10)
1.在如图1所示的直角坐标系中,在直线x=2“和y轴所夹的区域内存在两个大小相等、方向相反的有界匀强电场,其中x轴上方的电场的方向沿y轴负方向,x轴下方的电场方向沿y轴正方向. 相似文献
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根据麦克斯韦的电磁理论:变化的磁场产生电场,变化的电场产生磁场.由于空间磁场随时间变化而形成的电场称为感生电场.感生电场的电场线为闭合曲线,无头无尾,像涡旋一样,所以也叫涡旋电场.如果和高中物理中提到的静电场中的电场线相比,“沿电场线的方向电势降低”的方法来判断涡旋电场中两点的电势高低,却遇到了困惑.其实涡旋电场和电场具有本质的差别. 相似文献
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公式U=Ed的物理意义是:匀强电场中两点间的电势差等于电场强度与这两点沿电场方向距离的乘积。将公式U=Ed变形为E=U/d,这个关于电场强度与电势差的关系的表达式有着更丰富的内涵:(1)电场强度的大小等于两点间的电势差与这两点沿电场方向距离的比值, 相似文献
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周文秀 《河北理科教学研究》2006,(1):50-51
在《电场》一章中,我们不可避免的遇到下列问题:沿等量同号点电荷连线上场强如何变化?沿其连线的中垂线场强又如何变化?沿等量异号点电荷连线上场强如何变 相似文献
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《赣南师范学院学报》2020,(6):27-31
采用三维电场仿真软件对100 keV超快电子衍射装置的直流光阴极电子枪在接入真空电极后的整体电场进行仿真,观察真空电极的工作特性及其对电子枪的影响.仿真结果表明,高压导线与真空电极连接的金属球表面电场约为4 kV/mm,处于易引发电晕放电的范围,放置PVC保护罩可阻挡其发展至空气击穿;真空电极大气压侧的陶瓷表面电场维持一较小值,不会发展出沿陶瓷表面的沿面放电;进入真空腔部分的电极导线表面电场最大值接近17 kV/mm,远超过电子枪阴极和阳极表面,极容易产生真空电子发射而导致真空击穿.在真空电极导线外套5 mm半径表面光滑金属长圆柱可有效降低表面电场,陶瓷材质效果更好,但由于陶瓷存在高电压下的间隙击穿和气孔击穿,陶瓷加工需严格. 相似文献
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赵坚 《中学物理教学参考》2011,(3):41
贵刊2010年9期发表了"电场线平行的电场一定是匀强电场"(以下称作"原文")一文中,作者利用反证法来证明如图1所示的电场中,一个电量为+q的电荷在外力作用下,沿图中矩形虚线路径,从A点出发经B、C、D最后回到A, 相似文献
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夏有浩 《南京广播电视大学学报》1999,(2)
通有稳恒电流的导体内,电荷的移动是由于导体内存在电场。但是导体内自由电荷并不真正自由,它在前进途中与构成导体的原子发生碰撞,碰撞以后,失去了它由电场加速而获得的定向速度,再由电场的作用下,沿电场方向继续前进。自由电荷始终沿着电场的方向——即沿着电力线作定向运动,换一句话说,电流的方向与电场的方向是一致的,那电流线和电力线是一致的。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献