Bidirectional propagation of lightning leader

The characteristics of initial leader of triggered lightning flashes are studied by use of a highspeed digital camera system with the rate of 1 000 frame per second and simultaneous measurements of current and electric field change with 0.1 μS time resolution. The results show that the altitude-triggered lightning was initiated by bidirectional propagation leader because of "current interruption" by air gap, whereas the grounded-triggered one was not. The onset of downward-moving positive leader was prior to that of the upward-going negative leader for 843 ms in an altitude-triggered lightning under the positive ambient electric field. The downward-moving leader, regardless of its polarity, would produce in-homogeneous distribution of luminosity (current) along the channel on the moment of connection to the ground.     

通信局点防雷接地方式及要求

从雷电基本知识、雷电防护的基本原则、通信局点的防雷接地方式和基本要求等3个方面,对设备防雷接地作了概述。     

建筑物的防雷与接地

根据工程实例探讨了现代建筑防雷技术,针对有关的雷害事故和损失,强调应转变观念强化防雷意识,优化防雷技术.提出了防雷设计中应注意的有关问题和可采用的具体措施.     

Spatial and temporal characteristics of VHF radiation source produced by lightning in supercell thunderstorms

The three-dimensional temporal and spatial characteristics of VHF radiation events produced by lightning discharges in three supercell thunderstorms have been analyzed based on the data measured by the lightning mapping array system with high time and space resolution. The results indicate that lightning hole (lighting free region) with about 5-6km in diameter or lighting ring (annular lighting free region) is associated with the strong updraft in thunderstorm.The lasting time of lightning holes is either short or long, being about 20min in a tornado-producing thunderstorm. The lightning holes appear before the occurrence of tornado.The lightning hole is the most obvious during the occurrence of tornado and some self-existent lighting radiation events appear at a height of 15-16km. The lightning channels of inter-cloud (IC) lightning discharge exhibit clockwise rotary structures and do not have clear bilevel structures in the vicinity of the tornado.The lightning holes are corresponding to the strong updraft region.The temporal and spatial distribution of lightning radiation events reveals the structure of strong updraft in supercell thunderstorms.Positive cloud-to-ground (CG) lightning discharges dominate in these thunderstorms and the peak of positive CG lightning flash rate appears, with the maximum of 6 per minute,after or before the occurrence of tornado.     

英语术语electricity汉语译名流变简释

现代汉语中,英语electricity对应的术语是电、电学。electricity从最初传入到概念完全被接受,经历了概念之中的不同属性特征“琥珀”“雷电”及“无处不在”的接受过程,同时经过了“琥珀气”“雷气”“阴阳气”“电气”等数次译名的迁衍,而以“电气”一词影响最大。古代汉语中“电”也具有探究自然现象“天空闪电”的成因及本源的主旨倾向。只是在electricity传入之后,中国古代“电”的含义逐渐拓展,直至被electricity所代表的西方电学的内涵所替代。     

基于亚网格时域有限差分法的改进雷电电磁脉冲计算模型

在利用均匀网格时域有限差分法(finite-difference time domain, FDTD)计算地闪回击电磁脉冲时,空间步长选取较大会导致计算结果中后期出现震荡,所以为了计算结果的准确必须采用较小的空间步长,导致计算效率低、内存需求大。为了解决这一问题,提出利用惠更斯亚网格技术改进计算模型,改进后的模型可以实现在距离雷电通道近、高频分量多的区域采用较小的空间步长,其余区域仍采用较大的空间步长,从而以较高的计算效率消除计算结果中后期的震荡。首先,分析了空间步长对均匀网格FDTD法的各个场分量计算结果的影响;其次,通过与均匀网格FDTD计算结果对比,深入研究了改进模型对水平电场中后期震荡的消除作用。结果表明：随着步长的增大,水平电场中后期震荡剧烈;在不同地面电导率、地闪回击速度下,改进后的计算模型均能以较高的计算效率得到准确的、无震荡的计算结果。     

浅析张峰水库川坡水电站防雷保护与接地设计

介绍了川坡水电站当地地理条件,通过对防雷保护、接地的设计原则和常发事故进行分析,并对水电站的反事故措施进行探讨,以求提高工程经济、稳定、可靠、安全运行水平.     

浅谈变电站防雷设计

概述了雷电的形成及雷击危害的几种方式,分析了变电站防雷设施现状,提出了变电站二次系统防雷的措施.     

如何降低雷害对铁路信号设备影响的探讨

根据雷害对铁路信号设备的影响,对产生雷害的原因进行了具体分析,针对雷害的特点提出了具体的解决方案,并对在实施过程中应注意的问题进行了探讨.     

黄山名松雷电灾害风险分析

雷电是威胁自然和文化遗产安全的主要自然灾害之一.正确的雷电灾害风险评估可以有效防止或降低风险,减少损失.使用统计软件对黄山闪电数据进行统计分析,研究与黄山地质地貌、雷电环境等相关的雷电活动规律及其可能对黄山松和游客的影响,利用IEC的方法并进行改进,以龙爪松为例,给出相关风险分析值.研究表明:龙爪松引起的人身伤亡风险较大,超过允许值.风险原因主要为若雷电直接击中龙爪松,由于旁络闪击及雷击的机械作用导致树木爆裂伤人,同时还有雷击引起接触和跨步电压导致人员伤亡事故发生的风险.而龙爪松遭雷击起火或爆裂引起的损毁风险较小,将会达到数百年一遇的几率.评估结果对黄山游客雷电安全管理具有重要意义,对国内外类似风景区的防雷工作具有指导意义.