共查询到20条相似文献，搜索用时 265 毫秒
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A. I. Boldyrev A. E. Vyazilov V. N. Ivanov R. V. Kemaev V. Ya. Korovin A. V. Melyashinskii K. V. Pamukhin V. N. Panov Yu. N. Shvyrev 《Geomagnetism and Aeronomy》2016,56(4):503-512
Measurements of the atmospheric electric field strength made by an electrostatic fluxmeter with a unique threshold sensitivity for such devices (6 × 10–2–10–3 V m–1 Hz–1/2 in the 10–3–25 Hz frequency range) and wide dynamic (120 dB) and spectral (0–25 Hz) ranges, are presented. The device parameters make it possible to observe the electric component of global electromagnetic Schumann resonances and long-period fluctuations in the atmospheric electric field strength. 相似文献
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The results of observations of disturbances in the lower and middle ionosphere and in the geomagnetic field accompanying the partial solar eclipse over Kharkov are presented. The ionospheric effects have been studied with the use of an ionosonde and measurements of the phase and amplitude of a radio signal with a frequency of 66.(6) kHz on the Moscow–Kharkov route, and the effects in the magnetic field have been analyzed with the help of a magnetometer–fluxmeter in the range of periods from 1 to 1000 s. Disturbances in both the lower and middle ionosphere, as well as in the geomagnetic field, have been detected. The observation results have been compared with the results of a simulation of physical processes accompanying the solar eclipse. A good agreement has been found between observational and modeling results. 相似文献
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本文分析了投弃式海流电场剖面仪的发展,简介了海流感生电场的基本原理,提出了投弃式海流电场剖面仪的技术方案.根据投弃式海流电场剖面仪的实际需求,研发了XCP海流电场传感器,并通过XCP探头的自旋转(16 r/s),实现了将海流电场信号AM调制并频移至海流电场传感器的超低噪声频段,解决了在高噪声背景下快速测量纳伏级微弱海流电场信号.设计实现了XCP探头前端弱信号处理电路,对海流电场微弱信号进行滤波提取的同时可实现对海流电场同向分量进行硬件电路补偿,在一定程度上克服了XCP探头下沉引起感生电场的强干扰.在XCP探头内部采用SoPC技术实现对海流电场信号、罗盘线圈信号和温度信息的快速测量及其数字化处理,并将数字信息以UART协议及LVDS物理层数传方式发送到XCP浮筒端.开创了长度2 km、直径0.1 mm漆包线动态数据传输技术,解决了XCP探头和XCP浮筒之间的数字化数据传输问题.根据XCP探头所采集的海流电场信号与罗盘线圈信号的同相分量In、正交分量Qn、基线量Bn数据,研究了XCP探测方法,从而计算出了海流的东向与北向相对速度分量VEr、VNr.采用所研发的XCP,在我国南海海域首次采集到海面至海下千米深度的XCP海流电场信息和海洋温度信息. 相似文献
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可控源音频大地电磁法(CSAMT)一直沿用大地电磁法(MT)的办法,通过计算电场分量与磁场分量的比值,求取卡尼亚视电阻率.而CSAMT场源已知,电场分量和磁场分量都与地下电阻率存在一定的关系,可以单独采用CSAMT电场分量或者磁场分量提取地下介质的视电阻率.本文通过分析电场分量与磁场分量的数据特性,提出利用CSAMT电场单分量数据进行视电阻率的计算,用改进的广义逆矩阵反演方法,使初始模型中的地电层数等于频道个数,克服了以往反演计算中层数较少的问题;实现全场区电场分量视电阻率曲线的拟合反演.同时对单分量视相位计算方法进行分析,结合山西大同地区积水采空区探测及数据解释结果,论证本文提出的单分量解释方法的有效性. 相似文献
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针对声电效应测井问题，提出了一种全波列数值模拟方法.该方法忽略声电效应测井 时转换电场对声场的影响,并将电场视为似稳场.采用点声源模型，依据Biot理论得出了井外 孔隙介质声场的表达式，运用这些表达式和似稳电场近似方法，导出了声电效应测井时转换 电场的计算公式.在计算出的转换电场波形中，有伴随斯通利波的电场、伴随纵波和横波的 电场、和临界折射电磁波场.在25kHz以下的频率范围内，依据这种方法计算出来的声电转换 波波形与依据完整Pride理论计算的波形一致. 相似文献
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The relationship between electric fields, height-integrated conductivities and electric currents in the high-latitude nightside electrojet region is known to be complex. The tristatic nature of the EISCAT UHF radar facility provides an excellent means of exploring this interrelationship as it enables simultaneous estimates to be made of the full electric field vector and the ionospheric Hall and Pedersen conductances, further allowing the determination of both field-perpendicular electric current components. Over 1300 h of common programme observations by the UHF radar system provide the basis of a statistical study of electric fields, conductances and currents in the high-latitude ionosphere, from which preliminary results are presented. Times at which there is significant solar contribution to the ionospheric conductances have been excluded by limiting the observations according to solar zenith angle. Initial results indicate that, in general, the times of peak conductance, identified from the entire set of EISCAT observations, do not correspond to the times of the largest electric field values; the relative contribution of ionospheric conductance and electric field to the electrojet currents therefore depends critically on local time, a conclusion which corroborates work by previous authors. Simultaneous measurements confirm a tendency for a decrease in both Hall and Pedersen conductances to be accompanied by an increase in the electric field, at least for moderate and large electric field value, a tendency which is also identified to some extent in the ratio of the conductances, which acts as an indicator of the energy of precipitating particles. 相似文献
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Electromagnetic geophysical methods often rely on measurements of naturally occurring or artificially impressed electric fields. It is technically impossible, however, to measure the electric field directly. Instead, the electric field is approximated by recording the voltage difference between two electrodes and dividing the obtained voltage by the distance between the electrodes. Typically, modelling and inversion algorithms assume that the electric fields are obtained over infinitely short point-dipoles and thus measured fields are assigned to a single point between the electrodes. Such procedures imply several assumptions: (1) The electric field between the two electrodes is regarded as constant or being a potential field and (2) the receiver dimensions are negligible compared to the dimensions of the underlying modelling grid. While these conditions are often fulfilled for horizontal electric fields, borehole sensors for recordings of the vertical electric field have dimensions in the order of ≈100 m and span several modelling grid cells. Observations from such elongated borehole sensors can therefore only be interpreted properly if true receiver dimensions and variations of electrical conductivity along the receiver are considered. Here, we introduce a numerical solution to include the true receiver geometry into electromagnetic modelling schemes, which does not rely on such simplifying assumptions. The algorithm is flexible, independent of the chosen numerical method to solve Maxwell's equations and can easily be implemented in other electromagnetic modelling and inversion codes. We present conceptual modelling results for land-based controlled source electromagnetic scenarios and discuss consideration of true receiver geometries for a series of examples of horizontal and vertical electric field measurements. Comparison with Ez data measured in an observation borehole in a producing oil field shows the importance of both considering the true length of the receiver and also its orientation. We show that misalignment from the vertical axis as small as 0.1° may seriously distort the measured signal, as horizontal electric field components are mapped into the desired vertical component. Adequate inclusion of elongated receivers in modelling and inversion can also help reducing effects of static shift when interpreting (natural source) magnetotelluric data. 相似文献
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利用国内大型风沙物理风洞实验模拟沙尘暴电现象,研究风沙起电机理,结果表 明,不同风速下不同沙粒会产生不同极性的电场强度和电位效应,风沙电随风速增大而增强 ,且随沙粒度增大而减小. 在沙漠区的16m,8m,4m和1m高度上观测到27次不同沙尘暴天气 过程的电场和风速随时间变化. 结果表明, 在晴天4个高度上的电场均为小正电场值,电场 随高度降低而减小,最大电场强度在5kV/m以下,日风速变化对各层电场起伏没有较大影响 . 有沙尘天气,各高度上的电场强度随风速变化而变化. 16m高度上电场均为负值,平均值 为 -20kV/m;中层8m 电场一般为较高正电场值,达到10～40kV/m,与16m高度上电场呈反相 关;下层1m 电场值变化一般很小,在1kV/m以下. 在强沙尘暴天气4个高度上的电场均为负 电值,电场值随高度降低而减小,16m高度上最大平均电场强度达到-200kV/m以上,瞬时值 超过 -2500kV/m,与晴天电场矢量相反. 相似文献
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电磁场数值模拟的背景场/异常场算法是三维正演的有效策略之一,优点为采用解析法计算电磁场背景场代替场源项、克服了场源奇异性,缺点为不适用于发射源布置于起伏地表或背景模型复杂的情形.总场算法是直接对电磁场总场开展数值模拟,其难点是有效加载场源、保证近区与过渡区数值解精度.本文以水平电偶源形式分段加载接地长导线源,并以电场总场Helmholtz方程为矢量有限元法控制方程,实现了基于非结构化四面体网格剖分的接地长导线源频率域电磁法三维正演.通过与均匀全空间中水平电偶源产生的电场解析解对比,验证了本文算法的正确性,并分析了四面体外接圆半径与其最短棱边的最大比值和四面体二面角最小值对数值解精度的影响规律.通过与块状高导体地电模型的积分方程法、有限体积法和基于磁矢量势Helmholtz方程的有限元法数值解对比,进一步验证了本文算法正确性,同时说明了非结构化四面体网格能够更加精细地剖分电性异常体,利于获得精确数值解. 相似文献
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《Journal of Atmospheric and Solar》2000,62(6):521-526
Cold dense plasma with the ionospheric origin is often observed in the outer magnetosphere with L values as large as 10. We have examined the electric field data accompanied by the cold dense plasma. The electric field data are obtained by the direct measurement of the drift motion of electrons released from electron guns. We get westward components of convection. In addition, there is an AC component of electric field in the ULF range larger than the DC component. If such a large variation of electric field exists in the vicinity of the stagnation point, the plasmaspheric plasma is expected to flow away to the outer magnetosphere. Then we have a test particle simulation by adding a potential variable in time. There is a particle outflow accompanied by the AC variation of electric field in the ULF range. If there are more complicated variations of electric field, it is possible that particles flow out frequently. 相似文献
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The electron cyclotron waves that originate at low altitudes (<0.5 RE) and observed by ground facilities have been studied in the presence of a weak parallel electric field in auroral magnetoplasma consisting of trapped energetic auroral electrons and cold background electrons of ionospheric origin. The model distribution for auroral trapped electrons is taken as Maxwellian ring distribution. An expression for the growth rate has been obtained in the presence of parallel electric field assuming that the real frequency in the whistler mode is not affected by the presence of the electric field. The results show that waves grow (or damp) in amplitude for a parallel (or antiparallel) electric field. The influence of the electric field is more pronounced at a shorter wavelength spectrum. An increase in population of energetic electrons increases the growth rate and thus, plays a significant role in the wave excitation process in the auroral regions. 相似文献
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《Journal of Atmospheric and Solar》1999,61(10):745-750
ELF magnetic field measurements from 10 to 135 Hz at Arrival Heights, Antarctica, are used as a proxy measure of global cloud-to-ground lightning activity. Simultaneous hourly recordings of the atmospheric electric field on the surface of the Earth at South Pole during December 1992 make possible a detailed comparison between global cloud-to-ground lightning activity and the atmospheric electric field. Although the mean diurnal variation of the ELF magnetic field and the atmospheric electric field exhibit a remarkable similarity in shape and phase, the hourly departures from their mean diurnal variations are poorly correlated. We quantify the variability of the atmospheric electric field which can be explained by global cloud-to-ground lightning activity through linear regression analysis. To estimate an accuracy of this method, it is applied to simultaneous measurements of the ELF magnetic field at Søndrestrømfjord, Greenland, for comparison. The resulting hourly contribution of global cloud-to-ground lightning activity to the atmospheric electric field in the Antarctic during December 1992 is ∼40±10%, and the contribution of global cloud-to-ground lightning activity to hourly departures from the mean diurnal variation of the atmospheric electric field is ∼25±10%. 相似文献
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强地震会造成电离层电场发生异常变化.基于大气层-电离层电动力学理论对地震电离层异常电场开展数值模拟和研究,将理论推导出来的电离层异常电场方程扩展到球面坐标系中,并且考虑到电离层层电导率的各向异性,建立新的地震电离层异常电场模式.引进一个电离层层电导率经验公式(Nopper and Carovillano,1979),对中低纬度地震电离层异常电场特性进行数值模拟.模拟结果表明:附加电流引起电离层异常电场范围远大于自身在地表上的分布.且发生在低纬地区的异常电场主要成分是纬向电场,在东西两侧显偶极子分布.在额外电流分布相同的情况下,夜晚生成的异常电场更显著,存在昼夜差异. 相似文献
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We analyze the variations in the horizontal and vertical components of the Earth??s electromagnetic field measured at nine points onshore along the southern part of Lake Baikal. It is found that variations with a period of a few tens of seconds have decayed 20 minutes before the earthquake. This is a regional effect. It is observed in the variations of the horizontal magnetic field. The intensity of the effect in the electric field is site-specific, which is due to the nonuniform distribution of electric conductivity in a medium, as revealed by the deep magnetotelluric sounding. The electric field also experiences a coseismic variation associated with the seismic wave. This effect is stronger pronounced in the vertical electric field. The bay-like anomalies that precede and accompany the Kultuk earthquake are revealed in the electric field of intraterrestrial origin and in the behavior of the electric tipper. These anomalies are concurrent with the rise of the ground water level in the borehole. The probable nature of the revealed anomalies is discussed. 相似文献
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微火箭电场仪的原理及其应用 总被引：24，自引：1，他引：23
介绍一种新型的雷雨云电场探测仪器---微火箭电场仪 ,由直径为 55mm×760mm农用消雹小火箭改装而成 .它利用导体在电场中感应电荷原理 ,由电场传感器、测量线路、1 680MHz遥测发射机及天线组成 .仪器特点是结构简单、高密集、超小型、快速机动、低功耗、低成本 .此仪器于 1 998年年初试飞成功 .电场探测范围 1- 1 0 0kV/m .探测高度为7 5km左右 .主要用于飞行器升空安全保障 ,以及气象部门对雷电、冰雹的探测和预警 相似文献
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J. Sun 《Geophysical Prospecting》2005,53(3):411-421
We use the integral equation for a d.c. electric field, published in the literature, to introduce the concept of the electrical reflectivity tensor into d.c. electric field modelling. It is shown that in d.c. electric field modelling, the electric reflectivity tensor can be obtained in exactly the same way as in electromagnetic modelling. As a result, for a d.c. electric field, the quasi‐linear and the quasi‐analytical approximations, as well as the quasi‐analytical series, can be constructed in exactly the same way as in electromagnetic modelling. If the primary field is uniform, and if the anomalous body is a uniform circular cylinder or a uniform sphere, the reflectivity tensor is zero order (constant), relating to the free surface charge density. Thus, for some homogeneous bodies that have simple shapes and are embedded in a uniform primary field, the electrical reflectivity tensor is not only a mathematical mechanism for obtaining approximate solutions, but also a physical reality. Indeed, the free surface charge density is defined as the change of the electric displacement vector across the boundary surface under consideration. If the primary field is caused by a point source, and if the anomalous body is a uniform sphere, the reflectivity tensor is second order, varying slowly within the sphere. The relationship to the free surface charge density can be established only when both the reflectivity tensor and the free surface charge density are approximated by the first terms of their series solutions. If the point source is far from the centre of the sphere, the corresponding reflectivity tensor reduces to zero order, and is independent of the observation position within the sphere, i.e. it is a constant. Therefore, the basic idea of the quasi‐analytical approximation, i.e. taking the reflectivity tensor outside the integral operator, is justified in the case considered here. 相似文献
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Huang Qinghua Ikeya Motoji and Huang PeihuaDepartment of Earth Space Sciences Graduate School of Science Osaka University Osaka Japan Department of Earth Space Sciences University of Science Technology of China Hefei China 《中国地震研究》1997,(1)
Electric field effect on animals has been studied to investigate its relation with seismic anomalous animal behaviors(SAABs)in China.Freshwater eel,crucian carp,catfish,and soft-shelled turtle responded to the threshold electric field of 1-10 V/m,while duck,goose,cat,sheep,pig,dog,and chicken all responded to the ground electric field of about tens of V/m,depending on the species as well as on individuals.Most of the behaviors caused by electric field were similar to those reported as SAABs such as alignment,sudden movement,panic,and convulsion.The intensity of electric field due to a major earthquake would have been over these threshold values.Numerical estimation based on an electromagnetic model of a fault has been made to induce SAABs as electric shocks to pulsed electric fields in electro-physiology.The seismic electric signals(SES)intensity might be estimated from the observation of SAABs. 相似文献