大气电场仪标定系统的设计与仿真

文章介绍了大气电场仪的标定原理及意义,采用 ANSYS软件对大气电场仪标定系统进行仿真分析,依次分析了板间距离、探头位置和电场边缘效应对静电场环境的影响,为标定系统的设计提供了可靠的依据.     

建阳市大气电场特征及其在雷电预警中的应用

通过监测地面附近一定范围内的大气电场,间接实现对云层中带电状况实时监测,对大气电场特征进行了分析归纳,并应用电场资料进行雷电临近预报的尝试,实际表明：扰动天气下的大气电场,如雷暴、强降水出现时,大气电场特点为电场方向和数值上均有明显的不规则变化。雷暴临出现前会出现一个较强的、持续时间在数分钟到几十分钟的负电场区,利用这个特性可进行雷暴的临近预报。     

大气电场的特征及雷电预警技术研究

近年来,由于高科技的迅猛发展及其在社会各个领域的广泛应用,城市中的雷电灾害已严重影响现代通讯和计算机的应用,并造成建筑物破坏、人畜伤亡等恶性事故的发生,因此人们防雷意识不断提高,对雷电预报的要求越来越迫切。本文以大气电场资料为基础,利用地面电场仪的组网观测,监测雷雨云中强雷电活动中心在地面产生的电场强度、极性以及闪电数等,并结合闪电定位系统及天气雷达等设备的监测,探究雷电现象与各类监测数据的相关性,期待能为雷电的监测和预报提供更好的方法,最大程度减少雷电灾害给人民生活和社会经济造成的损失。     

基于DNDY大气电场仪的雷电监测系统的建设

为了提高雷电预警和雷电防护技术,有效探测雷电的发生,2012年四川省气象局在21个地市州建立了24部大气电场仪,形成了对特定区域的雷电短时预警,以避免和减轻雷电可能造成的灾害和损失.文章对DNDY大气电场仪的主要结构、功能、业务范围及布网情况进行了详细介绍.     

Hybrid inversion method for equivalent electric charge of thunder cloud based on multi-station atmospheric electric field

This article proposes the hybrid method to inverse the equivalent electric charge of thunder cloud based on the data of multi-station atmospheric electric field. Firstly,the method combines the genetic algorithm( GA) and New ton method through the mosaic hybrid structure. In addition,the thunder cloud equivalent charge is inversed based on the forw ard modeling results by giving the parameters of the thunder cloud charge structure. Then an ideal model is built to examine the performance compared to the nonlinear least squares method. Finally,a typical thunderstorms process in Nanjing is analyzed by Genetic-New ton algorithm with the help of weather radar. The results show the proposed method has the strong global searching capability so that the problem of initial value selection can be solved effectively,as well as gets the better inversion results. Furthermore,the mosaic hybrid structure can absorb the advantages of tw o algorithms better,and the inversion position is consistent with the strongest radar echo.The inversion results find the upper negative charge is small and can be ignored,w hich means the triple-polarity charge structure is relatively scientific,w hich could give some references to the research like lightning forecasting,location tracking.     

一种小型三维电场传感器

电场传感器广泛用于电场强度的探测。目前一般探测电场强度一维或二维方向分量，所检测数据尚无法精确地反映电场强度的实际大小。本文介绍一种小型三维电场传感器，由1路轴向和2路径向电场测量单元、驱动单元、电路单元以及保温单元组成，可用于探测空中电场强度的三维方向矢量。高空低温模拟试验中，在-70℃的环境温度下，传感器内部温度一直保持0℃以上，能充分保证传感器内部电路板的正常工作。在实际标定与测试中，该传感器表现出输出信号与电场强度的预期理论关系，证明厂三维电场传感器结构设计和检测方法的合理性。     

雷暴过程中的大气电场特征与地闪活动分析

本文利用云南省闪电定位系统监测资料和大气电场仪资料分析了滇中2007-04-30的雷暴天气过程,结果表明:这次由午后强对流活动引发的雷暴过程主要分布在滇中地区,负地闪所占比例较高,正负地闪为中等偏弱电流,在时间上正地闪落后于负地闪;大气电场不仅能很好的反映带电云的产生、聚集、消亡过程,也能较好的反映出地闪发生频数、性质;结合地闪发生频数,可将大气电场的演变可分为6个阶段,各个阶段显示出不同的电场特征,其中地闪初期阶段电场的变化对雷电预警具有重要意义。     

电场仪标定系统设计

介绍了一种电场标定系统的原理、设计方法及应用。整个装置由单片机系统进行高精度数据采集控制,控制高压源输出高电压连接平行板模拟均匀电场,最终将电场仪测得的电场值送入上位机软件通过与理论电场值的对比达到标定的目的。通过对多台电场仪的标定,均获得了与理论计算值相符合的结果,为电场测量的可信度与对比度提供了可靠的依据。     

Laser assisted field evaporation of oxides in atom probe analysis

We have investigated the laser assisted field evaporation phenomena of ZnO, and MgO to explore the feasibility of quantitative three dimensional atom probe analyses of insulating oxides. To assist the field evaporation of these oxides, the usage of short wavelength 343 nm ultraviolet (UV) laser was found to be more effective than 515 nm green laser. We observed field ion microscopy (FIM) image expansion and mass peak shifting when 343 nm laser was irradiated on MgO. This phenomenon can be attributed to the laser induced electron excitation which causes the reduction of the resistivity of the specimen.     

Near field optical microscopy in aqueous solution: implementation and characterization of a vibrating probe

Near field optical microscopy (NSOM) is one of the possible solutions to circumvent the diffraction limit, but the control of the optical probe in solution has been a technical challenge for practical applications. Most recently, it has been shown that the pipette used in the scanning ion conductance microscope can be modified to form a high resolution near field optical probe. When combined with a novel distance modulation mechanism, a robust near field microscope can be constructed for operation in aqueous solution. In this paper, we present technical details of this design and a further characterization of the NSOM system for imaging in solution. Fundamental limitations of this approach in comparison to other systems are also discussed. Based on the current technology, it is concluded that better than 50 nm resolution should be achievable with this technique for fluorescence, as well as fluorescence resonance energy transfer, imaging of biological specimens.