电力工程项目管控系统之信息化——领导查询需求设计和实施     

刘龙武 《中国勘察设计》2009,(1):45-48

做领导查询需求难,领导也讲不清;领导查什么？表格和图表。这是本文要介绍的主要原因及内容,本人通过公司信息化建设近十年的经验,一般员工到领导的信息需求都经历过,对过程体会较深。通过下面内容的简单扼要介绍为领导查询的设计提供一些意见。  相似文献   

淮南六方堤多层土堤基塑流稳定性计算     

桂和荣  李大云  杨学明 《工程地质学报》1999,7(1):60-64

本文研究了台阶状六方堤堤体荷重的弗里哀级数展开式和堤基应力计算系数的计算原理,通过堤基应力计算和塑流判别,对六方堤多层土堤基塑流稳定性进行了评价。  相似文献   

正环境电场中闪电先导的始发和传播   总被引：11，自引：9，他引：2  

王才伟  刘欣生 《高原气象》1998,17(1):65-74

为了研究中国内陆高原雷暴正极性闪电放电的特点,中日两国科学家于１９９７年７～８月在甘肃省平凉市联合进行了人工触发闪电野外实验。利用设在离触发点约３．５ｋｍ处的高速数字化摄像系统结合在闪道底部的电流测量记录,对在正环境电场中触发的两次闪电的初始先导的发生和发展特点进行了研究。资料分析表明,这两次触发闪电都是由火箭顶部始发的上行负先导传输入云而形成短暂的连续电流放电过程,整个放电持续时间分别只有１７和２６ｍｓ。先导在垂直方向的传输速度随时间而增加,平均值约为３．５×１０５ｍ／ｓ。正环境电场中的先导在向云底传输过程中可能产生多个分枝,但它们一般只存在几毫秒时间就消亡了,只有少数分枝能够发展入云。主通道的亮度综合反映了各分枝亮度的变化,而它本身又与在闪道底部测量记录到的闪电放电电流变化存在很好的对应关系。  相似文献   

人工触发闪电放电过程分析：I.先导放电过程   总被引：4，自引：3，他引：1  

言穆弘 《高原气象》1998,17(3):271-279

利用人工触发闪电电场,电流和闪电通道亮度高速摄像观测资料,分析了第一次回击前衔导过程的放电特性,结果指出,对于空中触发,先导传输具有“双向”特征,由于下行先导发展,先导通道电流分布具有不均匀性,连接导线汽化都发生在上行先导阶段。人工闪电第一次回击虽然与自然闪电继后回击特性十分相似,但两者放电特征仍有差别,前者具有曾长的连续电流过程。  相似文献   

高矮建筑物多上行先导连接过程的数值模拟          下载免费PDF全文

雷艺楠  谭涌波  余骏皓  郑天雪 《应用气象学报》2022,33(1):80-91

运用改进后的三维多先导模型,允许高矮建筑物上均可以始发上行先导,对多次地闪的连接过程进行模拟.结果 表明:矮建筑物始发上行先导和被击中的概率较小,高建筑物对矮建筑物上行先导的始发具有较明确影响.建筑物间的高度差是影响上述连接过程的主要因子,当建筑物间高度差较小时,高建筑物对矮建筑物的屏蔽效应不明显,下行先导通道的相对位...  相似文献   

Concurrent Upward Lightning Flashes from Two Towers          下载免费PDF全文

JIANG Ru-Bin  SUN Zhu-Ling  WU Zhi-Jun 《大气和海洋科学快报》2014,(3):260-264

Upward lightning flashes initiated simultane- ously from two towers separated by a distance of 3420 m were analyzed in detail based on high-speed camera images and S-band Doppler radar echo intensity. Both discharges lasted more than 250 ms and were self-initiated from the towers in the form of upward positive leaders with a time difference of less than 4 ms. Abundant recoil leaders oc- curred transiently in the remnant channel sections during the development of the upward lightning. The number of recoil leaders over the lower tower was greater than over the higher tower. When the concurrent upward flashes occurred, the radar echo intensity in the area of the towers was no more than 45 dBZ and the towers were separately located beneath two echo centers with low altitudes of 2-3 kin.  相似文献   

Investigation of pressure variations over stepped spillways using smooth particle hydrodynamics     

《Advances in water resources》2014

In this paper the smoothed particle hydrodynamics, (SPH), technique is used to investigate the pressure distribution on steps located in the non-aerated flow region of a stepped spillway for different discharges typical of skimming flow conditions. The open source code 2D SPHysics has been employed after being validated against the laboratory model studies of flow over broad crested weirs and flow over stepped spillways. The numerical results, in terms of the water surface and velocity profiles at different sections, are in good agreement with the corresponding experimental results. The code is then applied to determine the pressure distribution on the vertical and horizontal step faces. Also, the aspects of the pressure pattern are described and the positions/magnitudes of the maximum and minimum pressure values are presented.  相似文献   

Total Lightning Characteristics and Electric Structure Evolution in a Hailstorm          下载免费PDF全文

郑栋  张义军  孟青  吕伟涛  易笑园 《Acta Meteorologica Sinica》2009,23(2):233-249

  相似文献   

Optical and Electrical Observations of an Abnormal Triggered Lightning Event with two Upward Propagations          下载免费PDF全文

ZHENG Dong  ZHANG Yijun  LU Weitao  ZHANG Yang  DONG Wansheng  CHEN Shaodong  DAN Jianru 《Acta Meteorologica Sinica》2012,26(4):529-540

This study investigates an abnormal artificially triggered lightning event that produced two positive upward propagations: one during the initial stage (i.e., the upward leader (UL)) and the other after a negative downward aborted leader (DAL). The triggered lightning was induced in a weak thunderstorm over the experiment site and did not produce a return stroke. All of the intra-cloud lightning around the experiment site produced positive changes in the electric field. The initial stage was a weak discharge process. A downward dart leader propagated along the channel produced by the first UL, ending at a height of approximately 453 m and forming a DAL. Under the influence of the DAL, the electric field at a point located 78 m from the rod experienced a steady reduction of about 6.8 kV m-1 over 5.24 ms prior to the initiation of a new upward channel (i.e., the second upward propagation (UP)). The second UP, which started approximately 4.1 ms after the termination of the DAL and propagated along the original channel, was triggered by the DAL and sustained for approximately 2.95 ms. Two distinct current pulses were superimposed on the current of the second UP. The first pulse, which was related to the sudden initiation of the second UP, was characterized by a more rapid increase and decrease and a larger peak value than the second pulse, which was related to the development of the second UP into the area affected by the DAL. The second UP contained both a similar-to-leader process and a following neutralization process. This study introduces a new type of triggering leader, in which a new upward discharge is triggered in an established channel by an aborted leader propagating along the same channel with opposite polarity and propagation direction.  相似文献   

地闪回击辐射场波形的重构及地闪放电参量的估算   总被引：4，自引：0，他引：4  

张其林  郄秀书 《高原气象》2003,22(3):252-258

根据地闪回击传输线电流模式重新确立了地闪回击辐射场与电流之间的关系式,并在观测实验的基础上,重构了不同距离范围内(15～50km,50～100km,100～150km)的地闪回击辐射场波形,重构波形与实测波形之间有很好的一致性。同时在合理的假定下,将回击辐射电场与电流之间的关系进一步推广到先导过程,并估算了地闪先导放电过程中的三个参量。发现首次回击前最后一个先导脉冲电流为2.7kA,通道的电荷密度为(0.135～1.35)×10-3C·m-1,负地闪回击过程中和电荷量为2.06C。  相似文献