Wavelet multiresolution based multifractal analysis of electric fields by lightning return strokes     

Xueqiang Gou  Mingli Chen  Yijun Zhang  Wansheng Dong  Xiushu Qie 《Atmospheric Research》2009,91(2-4):410-415

Lightning can be seen as a large-scale cooperative phenomenon, which may evolve in a self-similar cascaded way. Using the electric field waveforms recorded by the slow antenna system, the mono- and multifractal behaviors of 115 first return strokes in negative cloud-to-ground discharges have been investigated with a wavelet multiresolution based multifractal method. The results show that the return stroke process, in term of its electric field waveform, has apparent fractality and strong degree of multifractality. The multifractal spectra obtained for the 115 cases are all well fitted to a modified version of the binomial cascade multifractal model. The width of the multifractal spectra, which measure the strength of multifractality, is 1.6 on average. The fractal dimension of the electric field waveforms ranges from 1.2 to 1.5 with an average of 1.3, a similar value to the fractal dimension of the lightning channel obtained by others. This suggests that the lightning-produced electric fields may have the same fractal dimension as its channel. The relationship between the peak current of a return stroke and the charge deposition in its channel is also discussed. The results suggest that the wavelet and scaling analysis may be a powerful tool in interpretation of the lightning-produced electric fields and therefore in understanding lightning.  相似文献   

The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line     

YanLi Xie  QiHao Yu  YanHui You  ZhongQiu Zhang  TingTao Gou 《寒旱区科学》2019,11(1):13-20

After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.  相似文献   

65米射电望远镜中频传输分配系统的研制     

袁瑾  苟伟  赵融冰  李斌 《天文研究与技术》2015,(3)

设计和实现了65 m射电望远镜中频传输分配系统,频率范围0.1~2.5 GHz,通道数6路,0~30 d B衰减本地和远程可调,链路增益、端口驻波比、分配输出隔离度、通道一致性等指标满足要求,给数字终端提供了良好的中频输入信号。经过系统验证,该中频传输分配系统整体性能优良,可以很好地满足射电观测的需求。  相似文献   

川西白玉县甘洛沟岩体特征及成因探讨     

勾永东 《四川地质学报》2001,21(2):80-85

松潘-甘孜造山带在燕山期经历了陆内俯冲是1：25万甘孜县幅区调中取得的重要认识，本文通过对甘洛沟岩体的时空分布、岩石学、岩石化学、岩石地球化学特征及岩体形成的构造环境等多方面综合分析，认为该岩体与区内其它燕山期岩体存在显著区别，它是在燕山期陆内俯冲动力学背景下的岩石图事件-下地壳拆沉的产物。  相似文献   

川西甘孜—雀儿山地区推覆构造的厘定     

勾水东 《四川地质学报》2001,21(4):193-198

1：25万甘孜县幅区调将测区推覆构造划分为岗嘎逆冲推覆构造和雀儿山滑覆构造。岗嘎逆冲推覆构造由三个叠瓦状排列的推覆片体组成，由南西向北东挤压推覆，具后展式叠瓦扇的特征，属B型俯冲推覆类型，雀儿山滑覆造为测区内逆冲推覆，地壳大幅压缩抬升之后造成的重力不均衡的产物，属重力滑动滑构造类型，其滑移方向向为北西向南东。  相似文献   

CSJ延时触发数字记录地震仪          下载免费PDF全文

邵安民  金东敏 《地球物理学报》1992,35(1):62-68

CSJ延时触发数字记录地震仪是一种便携式三路数字记录地震仪.它具有触发和定时控制两种工作方式,适合于记录区域性地震和人工地震.与之配套使用的回放仪,有串行和并行两种接口,便于联机处理.经野外实地观测,效果良好.  相似文献   

东疆星星峡地区白石头泉高铷氟花岗岩的特征和成因   总被引：6，自引：4，他引：6  

顾连兴  杨浩 《岩石学报》1994,10(1):41-53

新疆哈密白石头泉高铷氟花岗岩体自中心往顶部可分为：淡色花岗岩、天河石花岗岩、黄玉天河石花岗岩和黄玉石英钠长岩等岩相。各岩相之间在矿物成分和结构构造上有着系统的变化。岩体的岩浆可能来自于挤压背景下富含泥质的地槽沉积物的超变质和部分熔融。其成岩作用包括了熔体中的直接结晶和岩浆晚期－期后热液的交代两个过程。高含量的氟对于岩浆的演化起着重要作用。  相似文献   

压磁地应力雷电干扰形态及其排除     

郭玉莲  油朝元 《地震研究》1994,17(1):67-72

本文通过对山东省长清地震台２０多年地应力观测资料的总结，分析研究了雷电干扰的形态、机理、途径，进而采取了防雷措施，并取得了较好的效果。  相似文献   

DZR—Ⅲ型厘米级卫星激光测距仪     

夏治中  叶文蔚  蔡庆福  郭唐永  夏炯煜 《大地测量与地球动力学》1993,(4)

本文叙述了由国家地震局地震研究所与中国科学院测量与地球物理研究所协作研制成功的DZR—Ⅲ型厘米级卫星激光测距仪的测距原理及主要性能。该设备已装备于武汉人卫激光测距站并已投入日常观测。经国外数据处理中心美国戈达德激光跟踪网(GLTN)和荷兰Delft大学航空工程系对观测资料进行预处理,单次测距精度已达到±2～3cm,测程为2万多公里。已能观测到目前国际上统一联测的所有带激光发射镜的卫星,观测资料已用于国际地壳动力学(CDP)、国际地球自转机构(IERS)和地中海地区为研究地震而建立的激光测距网的计划(WECENER—MEDLAS)。  相似文献   

一次局地暴雨的地闪特征及其与强降水的关系     

苟阿宁  王晓玲  龙利民  刘希文  牛奔 《气象科技》2015,43(5):911-917

利用闪电定位仪每分钟实测资料、加密自动站逐分钟雨量和卫星云图云顶亮温TBB资料,对2013年4月29日西南涡东移过程中MCS产生的局地暴雨地闪特征进行了分析。结果表明：这次过程产生了大量地闪活动,且地闪主要出现在西南涡东侧500 hPa槽前辐合上升运动区、700 hPa暖切南侧850 hPa暖切北部的辐合带、TBB小于等于220 K区域南侧TBB水平梯度大值区的叠置区。整个过程负闪占主导地位,强降水发生在负闪密集区;MCS生命史不同阶段的正负闪频数、密集程度和分布位置是不同的。进一步分析发现单站地闪频数与TBB和强降水在时空变化上有一定的相关性,地闪频数和TBB表现为负相关,即TBB下降到最低值时,地闪频数则到达峰值;逐时地闪频数和雨强均呈单峰分布,负闪频数和强降水发展演变趋势一致,负闪峰值和最大雨峰时刻对应,正闪或和最大雨峰一致或略滞后,正负闪和雨峰的6 min演变趋势呈多峰分布,负闪初现12~18 min后出现降水,负闪突增较强降水有18~24 min的提前量。此个例显示MCS将朝向移动路径前侧的负闪密集区域移动,负闪密集区对局地强降水的落区和强度有较好的指示意义。  相似文献