大型电力工程场地地震危险性研究现状与展望   总被引：1，自引：0，他引：1  

程小久 《华南地震》2000,20(1):71-78

概述了工程场地地震危险性分析的研究简史、内容和方法,并就研究工作中存在的问题和发展趋势进行了讨论.提出了利用GIS技术研制我国大型电力工程地震危险性分析信息系统的建议.  相似文献   

Bifurcation of the tail current sheet in Jovian magnetosphere     

P.L. Israelevich  A.I. Ershkovich  R. Oran 《Planetary and Space Science》2007,55(15):2261-2266

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On transient electric potential variations in a standing tree and atmospheric electricity     

Jean-Louis Le Mouël  Dominique GibertJean-Paul Poirier 《Comptes Rendus Geoscience》2010,342(2):95-99

Transient electric potential variations have been observed in a standing poplar tree equipped with electrodes up to a height of 10.5 m. The simultaneous signals at all electrodes have the same shape and their amplitude grows linearly with height, up to values of 10 to 50 mV. This corresponds to an electric current through the tree of the order of a few μA. The frequency of appearance of the signals does not depend on the season or on the time of the day. It is suggested that the potential variations are caused by the passage of thunderstorm clouds, of little activity, whose electrically charged base could induce charges in the ground and give rise to a current flowing through the tree and discharging at its top by point discharge.  相似文献   

混合物整体电导率的研究   总被引：7，自引：0，他引：7       下载免费PDF全文

李剑浩 《地球物理学报》2005,48(6):1406-1411

研究由几种导体成分掺杂的混合物的整体电导率.对欧姆定律求平均,得到混合物电导率定义.对电流连续性方程求平均,得到混合物中电场增量方程.求电场增量方程在同种成分上的平均,并结合混合物电导率定义,得到混合物电导率公式.现有的三种混合物结构下电导率公式（电导率串联公式、并联公式和整体各向同性混合物电导率公式）都是混合物电导率公式的特例.进一步分析得出结论,混合物整体电导率是各成分电导率与整体电导率结构并联后的体积串联.  相似文献   

The Electric Field During Blowing Snow Events     

Mark Gordon  Peter A. Taylor 《Boundary-Layer Meteorology》2009,130(1):97-115

A model is proposed to determine the electric field strength in blowing snow. To test this model, the electric field strength was measured over an 80-day period during the Canadian Arctic Shelf Exchange Study (CASES) in 2004. The electric field strength at 0.5 m correlates well with the difference between 10-m wind speed and a threshold wind speed, although there is a large amount of variation between the electric fields generated during different blowing snow events. Although the model predicts that the electric field should be proportional to particle number density, the correlation is weak. The correlation of wind speed and electric field strength suggests that particles become charged primarily due to friction-induced temperature difference as they impact upon the surface. The strength of the electric field is likely influenced by a large number of other factors that are difficult to measure. However, the model predicts electric field strengths in excess of 25 kV m⁻¹ near the surface, which would have a significant effect on particle motion.  相似文献   

Comparative analysis of the initial stage in two artificially-triggered lightning flashes     

J. Yang  X. Qie  Q. Zhang  Y. Zhao  G. Feng  T. Zhang  G. Zhang 《Atmospheric Research》2009,91(2-4):393-398

The initial discharge stages of two flashes during the Shandong Artificially Triggering Lightning Experiment (SHATLE) are analyzed based on the synchronous data of the current and close electromagnetic field. For a lightning flash, named 0503, the wire was connected, not electrically, but via a 5 m length of nylon, with the lightning rod; while for another, named 0602, the wire was connected with the rod directly. Results show that the discharge processes of the initial stage (IS) in flash 0503 are quite different from that of the usual classical-triggered flash 0602 and altitude-triggered flashes. A large pulse with a current of about 720 A resulted from the breakdown of the 5 m air gap during flash 0503, and the corresponding electric field at 60 m from the lightning rod was 0.38 kV/m. The upward positive leaders (UPLs) propagated continuously from the tip of the rocket after this breakdown. The geometric mean (GM) of the UPL peak current was 23.0 A. Vaporization of the wire occurred during the initial continuous current (ICC) stage and the largest current pulse was about 400 A. Compared with triggered flash 0503, the discharge processes of IS in flash 0602 were simple, only two large pulses similar to each other occurred before dart leader/return stroke sequences. The peak current of the first pulse was 2.1 kA and its corresponding electric field and magnetic field at a distance of 60 m from the lightning rod were 0.98 kV/m and 7.03 μT, respectively. During the second pulse, the wire disintegrated. The current decreased to the background level at the moment of the wire disintegration. The current of the second pulse in triggered flash 0602 was 2.8 kA, and the corresponding electric field and magnetic field at 60 m from the lightning rod were 1.22 kV/m and 9.01 μT, respectively.  相似文献   

强风暴个例电荷结构及云闪放电差异的数值模拟   总被引：1，自引：0，他引：1  

周志敏  郭学良  崔春光  李兴宇  付丹红  赵玉春 《高原气象》2012,31(3):810-824

利用耦合电过程的冰粒子分档模式对长春地区两个降雹型和非降雹型强风暴个例的闪电特征进行了模拟和对比分析。结果表明,在雷暴云的初始发展期,由于上升气流较弱,两者电荷分布相似,均表现为弱的正偶极结构。随着云体不断发展,两者电荷分布开始表现出差异:降雹型个例中的上升气流较强,风切变较大,过冷水能被携带到较高的高度,冰相粒子也能被带到较高处或在较高处继续增长,使得不同区域均存在冰相粒子含量中心。因此,冰相粒子的发生范围不同、环境参数不同及荷电符号不同的非感应起电过程,形成多个电荷中心,电荷结构易出现多层分布。在不同的发展时期电荷结构均呈现出不同的形态,放电既可能在上升气流区触发,也可能在气流辐散区触发。相对而言,非降雹型个例中的上升气流较弱,风切变较小,冰相粒子的分布较规则,非感应起电过程较均匀,从而导致电荷分布始终较均匀。不同发展时期的电荷结构都相对有规则,满足放电条件的位置具有一定的相似性。  相似文献   

几次大震前的地面和空间电磁场变化   总被引：5，自引：3，他引：2       下载免费PDF全文

刘君  杜学彬  范莹莹  安张辉  解滔  郑国磊  谭大成  陈军营 《地球物理学报》2011,54(11):2885-2897

本文应用非线性谱估计方法(MEM方法)、电/磁场脉冲能量统计方法,处理了四川汶川MS8.0 (2008)、新疆于田MS7.3 (2008)和青海玉树MS7.1 (2010) 地震及强余震附近的地面电/磁场和Demeter卫星电离层磁场观测数据,研究了地震电/磁场变化,得到:在震中附近及周围出现了震前地电/地磁场极低频成...  相似文献   

电导法测定LiCl在水溶液中的活度系数          下载免费PDF全文

王卫东 《盐湖研究》2005,13(4):35-38

应用电导法测定了LiCl水溶液的活度系数,首先在288~308 K温度范围内测定LiCl在极性水溶剂中的电导率,利用公式计算LiCl的摩尔电导率,应用Debye-Hücker和Osager-falkenhangen公式计算LiCl在水中的活度系数,并讨论了温度和浓度对LiCl水溶液活度系数的影响。  相似文献   

WHEN THE LIGHTS GO OUT IN CHESHIRE*     

GEOFFREY L. BUCKLEY  NANCY R. BAIN  DONALD L. SWAN 《Geographical review》2005,95(4):537-555

ABSTRACT. The purchase and subsequent demolition of Cheshire, Ohio‐located in the shadow of the General James M. Gavin Power Plant‐has attracted national attention. According to a New York Times report, “the deal … is believed to be the first by a company to dissolve an entire town.” In this article we consider historical precedents for the case, explore the thirty‐year history of community‐plant relations in Cheshire, and recount the series of incidents that ultimately led to the town's sale. We discuss the impact that the town's sale has had on the local community and the larger implications of American Electric Power's actions.  相似文献