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（一） 在電測井的時候,工業交流電常常由於線路中存在漏電現象或感應现象而進入测量線路,有時还經過線间電容或由MN電極而進入測量線路。工業交流電的頻率一般是50週或60週,頻率已經相當高了,對電測電流計來說已超過其頻率響應範圍,不會影響测量結果。但是在作電阻法測井（KC）時,由於線 相似文献
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引言在前一篇文章中,我們討論了繞垂直軸旋轉橢球體的自然電場和解釋。本文將討論水平旋轉橢球體的自然電場和其解釋方法。水平旋轉橢球體的自然電场 設垂直極化的水平旋轉橢球體位在一均匀各向同性無限大的介質里,其電阻率為 相似文献
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分析了乌恰5．7级地震前喀什-乌恰地区的地震活动情况和地震学参数异常过程。研究认为，5．7级地震发生在1996年9月以来形成的喀什西南4．0级以上地震空区的边缘，此次地震的活动间隔时间为1980年以来之最；震前有6项地震学参数空间扫描和5项地震学参数时间进程存在中短期异常；震前3级地震活动强度有多次起伏。 相似文献
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库玛断裂带强震活动与地震空区研究 总被引：12，自引：0，他引：12
库玛断裂带作为青藏高原内部的一条强地震活动带, 1900年以来发生过3次7级地震,其中2次7级大震前均出现5级以上地震的背景空区,表明背景空区对该带大震具有中长期预报意义。最近一次背景空区业已形成,并出现与之配套的孕震空区,其演化图像符合强震孕育模式。研究发现,库玛断裂带中段ML 3以上地震空区,对共和7级强震及周边200 km的强震有前兆意义。 相似文献
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主要使用了USGS全球地震查寻结果,对比研究了本世纪至今印尼苏门答腊地震的构造背景、巨大地震及其余震的活动特征,其主要结果如下:①巨大板块地震很少在原地重复发生.有迁移性和明显的填空特征;2000年之前的四次巨大地震具有明显向北迁移的特征,2000年之后三次巨大地震具有明显向南迁移和填空的特征;②2000年8.3级地震余震区南段存在约170 km的5级空段;③2004年9.0级地震余震填充了在巽他海沟东侧长约1 000 km的8级空段,其余震区南段存在约200 km的5级空段,沿板块边界形成的余震带具有明显向北迁移的特征;④2005年8.7级地震发生在2004年9.0级地震的200 km的余震空段上,余震分布不但填充了2000年8.3级地震170 km余震区5级空段,而且其余震区南段还存在约200 km和300 km的2个5级空段;⑤2007年8.5级地震发生在2005年8.7级地震约300 km余震空段的最南端,其7.9级最大余震发生在2005年8.7级地震约300km余震空段的最北端,使约300km余震空段的能量得到了充分释放;⑥2005年8.7级地震约200km余震区5级空段内的能量有可能还未得到释放,该地区是否还会发生一次巨大地震,还有待进一步研究. 相似文献
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根据地震空区的特征,选定了七个参量作为空区的判别标识,并发展了一套用计算机自动识别空区的程序。对于所研究的地区,程序中按一定间隔选择待分析的判别地区中心点。然后,由程序按给定的七个参数之值判定在每一点周围是否存在地震空区。如果识别出了一个空区,它的位置和形状即用一条与其拟会的二次曲线的参数来描述。对不同时段的地震目录数据作同样的扫描识别,最后确定出符合判别标识的空区出现次数、各次持续时间、空区长短轴及其取向、空区面积等参数。 相似文献
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通过一年多对四川地区地震活动性的前兆研究进行清理,就以下几项课题的研究情况做一概述。 1.地震空区 笔者和席敦礼采用从R-t图寻找平静段,再在相应时段震中分布图上结合构造条件圈定平面空区的办法,对1970年7月到1983年6月四川地区有资料的16组5级以上地震前是否出现空区进行了清理,结果有10组在震前出现空区,占5/8,2组7级以上地震前均出现空区,5组6.0—6.9级地震中,有4组震前出现空区。根据空区形成过程,可分 相似文献
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引言在尋找硫化物礦體時,經常應用自然電場法。由於這種礦體的形狀是多样而十分複雜,對其觀察結果,現在廣泛應用的定量解釋方法為近似地把礦體看作球狀,圓柱狀或板狀來解釋。而對於最常遇到的透鏡狀礦體則尚未見到簡單的解釋方法。本文近似地把透鏡狀礦體看作繞垂直軸旋轉的橢球體。下面我們先來研究它們產生的自然電場,然後研究其定量解釋方法。 相似文献
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Swept-frequency (1/10 MHz) ionosonde measurements were made at Helston, Cornwall (50°06N, 5°18W) during the total solar eclipse on August 11, 1999. Soundings were made every three minutes. We present a method for estimating the percentage of the ionising solar radiation which remains unobscured at any time during the eclipse by comparing the variation of the ionospheric E-layer with the behaviour of the layer during a control day. Application to the ionosonde date for 11 August, 1999, shows that the flux of solar ionising radiation fell to a minimum of 25±2% of the value before and after the eclipse. For comparison, the same technique was also applied to measurements made during the total solar eclipse of 9 July, 1945, at Sörmjöle (63°68N, 20°20E) and yielded a corresponding minimum of 16 ± 2%. Therefore the method can detect variations in the fraction of solar emissions that originate from the unobscured corona and chromosphere. We discuss the differences between these two eclipses in terms of the nature of the eclipse, short-term fluctuations, the sunspot cycle and the recently-discovered long-term change in the coronal magnetic field. 相似文献
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《Journal of Atmospheric and Solar》2000,62(2):133-140
In 1995–1996, observations were carried out at Norilsk (geomagnetic latitude and longitude 64.2°N and 160.4°E) to determine dynamic parameters of irregularities in the high-latitude ionosphere. The short-baseline spaced-receiver method that has been implemented at the ionospheric facility of the Norilsk Integrated Magnetic–Ionospheric Station, provides a means of simultaneously measuring parameters of small-scale irregularities (spatial scale of 3–5 km) by the Similar-Fading Method (SFM), as well as of medium-scale irregularities (time scale of 10–30 min, spatial scale of hundreds of kilometres) by the Statistical Angle-of-arrival and Doppler Method (SADM). About 20 h of the observational data for the F2-layer under quiet geomagnetic conditions (Kp < 3), 20 h under disturbed conditions (Kp ≥ 3) and about 15 h for the sporadic E-layer (Kp ≈ 3) were processed. It has been found that the propagation directions and velocities of different-scale irregularities do not coincide. Small-scale irregularities of the F2-layer travel predominantly eastward or westward. The velocity of the F2-layer irregularities is about 100 m/s, and under disturbed conditions it is up to 200–250 m/s. Small-scale irregularities of the sporadic E-layer travel mostly in the northward direction. It is confirmed that the Es-layer is characterised by high velocities of the irregularities (as high as 1000 m/s). Medium-scale irregularities with periods in the range of 10–30 min travel mostly in a southward direction with velocities of 20–40 m/s. 相似文献
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Summary The behaviour of the ionosphere over Genova during the solar eclipse of February 15, 1961 is investigated. For theE-layer the effect was very marked, but the value obtained for the recombination coefficient is above normal. The effect of the eclipse was also observed on theF2 layer; however, the behaviour here appears affected by the simultaneous occurrence of an ionospheric perturbation. Finally, the maximum reduction of the ionospheric absorption on 2 and 3 Mc/s during the eclipse was found to be of the order of about 12 db.This report belongs to a set of investigations on geophysical effects of the solar eclipse of February 15th, 1961 carried out by the «Istituto Geofisico, Università di Genova», and made possible through a financial support of the «Consiglio Nazionale delle Ricerche». 相似文献
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XueWu Cheng Yong Yang ZeLong Wang FaQuan Li GuoTao Yang ZhengYu Zhao Wei Gong JiHong Wang Xiong Hu Xin Lin XiaoCheng Wu ShaLei Song ShunSheng Gong 《中国科学:地球科学(英文版)》2016,59(2):418-424
During the total solar eclipse on July 22, 2009 in Wuhan, the joint observation test of Na layer and ionosphere was conducted by using the daytime observation atmospheric lidar and the GPS ionosphere detector. The results show that the full width at half maximum (FWHM) of Na layer density slightly narrowed during the total solar eclipse and broadened after the eclipse, while the height of Na peak slightly decreased in the eclipse and increased after the eclipse. These implying that Na layer changes reflect the rapid process of sunrise and sunset. The ionosphere total electron content (TEC) and the sky background light noise also presented an obvious fluctuation characteristic with the changes of solar irradiation during the process of total solar eclipse. The difference lies in that the changes of FWHM of Na layer atoms are much slower than that of ionosphere, the reason for this might be that the Na layer, after being disturbed by the total solar eclipse, will generate a series of complicated photochemical reactions and momentum transport processes, and then recombine the Na atoms. The Na atoms to be detected by the lidar need a lag process, which rightly conforms to the theoretical simulated results. 相似文献
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2009年7月22日发生在亚太地区的日全食,从北半球中纬地区一直延伸到南半球中纬地区.这次日食期间发生的磁暴和日食时间同步,使得电离层变化较为复杂.为了分析日食期间电离层扰动及其对定位的影响,所采用的GPS数据来源于日全食带内的重庆CORS网(4个站)、武汉CORS网(8个站)数据、IGS站WUHN、SHAO的数据,以及日偏食区域内不同纬度处的若干IGS站.通过比较日食前后连续三天的各个地方TEC变化,以及利用高采样率的CORS网数据研究日食期间TEC的瞬时变化,根据位置和时间的不同,各地日食期间TEC下降约(1~4)TECU.但是,磁暴期间TEC的响应整体表现为正相暴,偏离值达50%以上,且和日食食甚后的TEC变化相重合.同时,求解了日食期间伪距单点定位的实时精度和CORS网内中短基线的实时精度,伪距单点定位的平面精度变化不显著,高程精度下降达数十米,日食初期CORS网中基线的平面精度仍在厘米级内,高程精度仍在分米级内,但是,日食后期发生的磁暴导致基线的平面精度下降到分米级,高程精度下降到米级. 相似文献
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L. F. Chernogor 《Geomagnetism and Aeronomy》2016,56(5):592-603
The results of the observations of aperiodic and quasi-periodic disturbances in E and F1 ionospheric layers and air temperature variations in the surface atmosphere on the day of the solar eclipse and control days are presented. The ionospheric processes were monitored by vertical sounding Doppler radar. The measurements showed that, near the time of the maximum coverage of the solar disk, the greatest decrease in the density of electrons in the layers E and F1 was ～27%, which is close to the calculated value (25%). The solar eclipse was accompanied by the generation of traveling ionospheric disturbances with a period of 8–12 min and a relative amplitude of electron density variations of ～0.6–1.5%. Because of the haze in the surface atmosphere, its temperature, which was monitored at observation points at a distance of 50–60 km from each other did not exceed 1°C near the time of the maximum eclipse magnitude. 相似文献
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Summary The geomagnetic records obtained at Genova during the eclipse of February 15th, 1961 are quantitatively interpreted with the aim of separating the eclipse effect. Using the ionospheric observations also made at Genova, the result is well confirmed by the calculations carried out applying both theChapman-model and theVolland-scheme for estimating the geomagnetic effect as originated by the changes of the current system flowing in theE-layer.This report belongs to a set of investigations on geophysical effects of the solar eclipse of February 15th, 1961 carried out by the «Istituto Geofisico, Università di Genova», and made possible through a financial support of the «Consiglio Nazionale delle Ricerche». 相似文献
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Summary The article first describes in chronological order the observations on the propagation of radio waves during the solar eclipses, and the development of the conflicting results on the similar transmissions of radio signals. The general theory of the absorption of radio waves in the ionosphere is briefly described and therefrom a method is derived to estimate the variation of the absorption of obliquely incident radio waves during a solar eclipse.The variation of field-strength can be studied in terms of the relationship between the vertical incident equivalent frequency of the signals and the critical frequencies of the ionospheric layers at the regions of reflection. The total absorption of radio waves consists of the non-deviative absorption in theD region and the deviative absorption in the higher layers of the ionosphere. During the eclipse, theD region absorption decreases in phase with the progress of the eclipse, but the variation of deviative absorption may differ in each observation. The deviative absorption is large when the equivalent frequency is close to the critical frequency of the layer reflecting the waves or of the layer just penetrated by the waves. The changes in the deviative absorption during an eclipse can be estimated on the basis of the variation of the critical frequencies of the ionospheric layers. The resultant changes in the total absorption during a solar eclipse may thus be estimated. The different types of field strength variation expected during an eclipse are given.The observations of the vertical incident absorption of radio waves and the field strength variations of obliquely incident continuous wave radio signals during the solar eclipse are described and the changes are explained on the basis of the above theory. 相似文献
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本文分析了1987年9月23日日环食期间,我国14个电离层站和1988年3月18日日全食期间两个站的垂测仪和偏振仪记录,并综合50年代以来历次日食电离层效应的观测结果,证实:1.E层和F1层光食效应明显,F2层动力学效应显著;2.f0F2存在日食日值大于、小于或等于控制日值三种典型情况;3.TEC食变曲线有凹陷和不凹陷两种典型情况,甚至出现日食日值大于控制日值的异常现象. 本文对F2层和外电离层的动力学特征作了定性讨论,认为:空间等离子体温度急剧下降和沿场扩散是F2层和外电离层日食效应的最主要因素;而磁赤道上空等离子体的沿场扩散、“喷泉”效应,热层风和全（环）食带方位是影响位于磁赤道异常区各电离层站日食电离层效应的主要因素. 相似文献