共查询到19条相似文献，搜索用时 406 毫秒
1.
本文导出了地下管线电流产生的倾斜磁场异常表达公式,计算出了观测点沿圆弧和水平地表主剖面移动时倾斜磁场的分布规律,指出了利用倾斜磁场最大值点确定管线深度时在原理上存在的问题和不实用性,阐明了错误的实质,给出了两个实例,证明了本文中所提出的理论。 相似文献
2.
在平顶山矿工路路面改造工程中,使用GX-2型及RD-4000型地下管线探测仪探测地下管网布设情况。根据地下管线种类、管线布设方位、埋置深度、探测难度大小进行了多次试验,在此基础上确定了电磁探测技术与方法：利用直连法提高被测管线中的交变电流,压制邻近平行管线和地下介质中的异常反映;在多管并存、且间距较小的情况下,应选择“梯度法”对磁场水平分量垂直梯度ΔHx进行观测,以得到最大清晰异常;另外,还应根据具体情况,合理选择诸如压制旁侧管线法、选择发射法、偏移感应法、动源发射法等发射方式,保证目标管线中有较强异常呈现。在管线密集区,应尽可能地降低工作频率,以减小旁侧管线中产生的二次电流及二次磁场;为防止信噪比下降,可适当减小收发距,以提高接收机的灵敏度。 相似文献
3.
确定地下管线深度的方法原理研究 总被引：1，自引：0，他引：1
从理论上阐述了利用倾斜磁场最大值点、利用垂直磁场分量峰值点和利用水平磁场分量半极值点确定地下管线深度的原理方法,指出了利用倾斜磁场最大值点确定管线深度时在原理上存在的问题和不实用性,同时从原理上和实用中筛选出了最佳的定深方法-水平磁场分量三角法. 相似文献
4.
平行地下管线探测技术与方法的研究 总被引：1，自引：0，他引：1
平行管线是地下管线探测工作经常遇到的管网结构,由于其间距小于2倍埋深,存在电磁场的相互感应和叠加,使探测工作难度加大.在电磁法探测应用中,可分别观测磁场的水平分量(Hχ)、垂直分量(Hz),根据其分量曲线特征判断地下管线的数量、位置及走向,进而确定其埋设深度.实践证明,为减小旁侧影响,避免其它电磁信号干挠,合理选择激发方式、激发位置对探测效果影响很大. 相似文献
5.
6.
长距离深埋管线的探测效果 总被引：5，自引：0，他引：5
介绍了水平定向钻在地下管线施工方面的应用状况;分析了不同埋深直线电流一次电磁场Hx、Hz的归一化异常的分布特征,以及确定地下金属管线的理论依据;提出了对深埋>3m的地下管线探测时应采用的频率、电流、远端接地等提高信噪比的技术对策,及利用水平磁场分量70%法确定管线深度的适用条件;列举了3个长距离、深度>10m过江深埋管线的探测实例,说明方法的有效性。 相似文献
7.
基于姿态测量的深埋小口径地下管道探测技术研究 总被引：1，自引：1，他引：0
鉴于非开挖深埋地下管线一直是城市管线探测中的难题,本文针对小口径非开挖深埋地下管线提出了基于姿态测量原理的探测方法,推导了磁三分量及重力加速度三分量姿态定向公式以及曲线构建公式,对误差校正等进行了分析.并对基于此原理研制的仪器进行了探测试验,给出试验结果,评价了该方法的有效性及优缺点. 相似文献
8.
地下近间距并行管线的电磁异常特征 总被引：1，自引：1，他引：0
用电磁管线探测仪对地下近间距并行管线探测时,往往受到旁侧管线的干扰,使异常形态畸变,因此不能简单地利用异常有几个峰值来判断有几条管线。电流方向对异常曲线形态影响较大,对地下多条近间距并行管线的定位和定深,只能采用没有受干扰或干扰较小的半边异常为根据。了解地下近间距并行管线的电磁异常特征,是消除或减少旁侧管线干扰、使探测结果达到精度要求的重要保证。 相似文献
9.
为了准确、高效探测地下管线,利用磁偶极子分析法模拟水平平行铁质管线模型,应用Matlab软件计算该模型产生的磁异常曲线,分析模型在不同参数变化下磁异常曲线的基本形态、峰值个数变化及原因。数值模拟结果表明,所选取参数对磁异常信号的幅值和磁宽均有影响:管间距离、埋深和磁化率明显改变了曲线的基本形态,影响曲线峰值个数;管线长度、外径和管壁厚度影响曲线幅值,不改变其基本形态;在相同参数条件下,分别应用Comsol软件与磁偶极子分析法计算磁异常曲线,结果归一化后对比发现曲线形状吻合,验证退磁效应影响磁异常曲线幅值,从而验证了磁偶极子分析法应用于平行管线模型正演分析的正确性。 相似文献
10.
《物探化探计算技术》2016,(3)
通过定源回线三分量模拟计算,归纳了定源回线三分量变化特征与地下板状体产状对应关系。在此基础上对夏日哈木铜镍矿区已知剖面的定源回线三分量数据进行分析和反演解释。结果表明,1充分利用三分量数据信息,有利于快速圈定异常中心在地面的位置;2根据水平分量的零等值线与发射框对称剖面(南北和东西向)的相对位置关系,可定性判断地下矿体顶界面的起伏状况或矿体产状变化情况;3结合Z分量一维反演结果与水平分量定性解释成果对照分析,表明了三分量数据联合解释有助于提高定源回线解释成果的可靠性。 相似文献
11.
B. P. Filippov 《Astronomy Reports》2009,53(6):564-568
Equatorward deviations of coronal streamers at solar minima and poleward deviations at solar maxima are interpreted as the effects of changes in the general topology of the global solar magnetic field. The streamer axis is located on the neutral surface of the radial magnetic field B r = 0, and the neutral surfaces deviate toward the field null points. The magnetic configuration with a null point (line) located at the equator is typical for the solar minima, while the null points are located on the rotational axis of the Sun at the solar maxima. 相似文献
12.
A. V. Mordvinov 《Astronomy Reports》2006,50(11):936-943
The asymmetry of the magnetic field of the Sun and its manifestation in the interplanetary magnetic field (IMF) are studied. The dominant magnetic polarity of the radial component of the IMF alternates from cycle to cycle, but with an overall systematic dominance of polarity directed toward the Sun. The global asymmetry is also manifest in the component of the IMF perpendicular to the plane of the solar equator. The dominance of positive values of B z together with an appreciable linear trend in the cumulative sum of this quantity is interpreted as a manifestation of a relic solar magnetic field. The strength of this relic magnetic field near the Earth is estimated to be 0.048 ± 0.015 nT, based on the growth of the linear component of the cumulative sum of B z . Time intervals, in which negative values of the B z component of the IMF dominate and enhanced geomagnetic activity is observed, are identified. Our analysis of solar and heliospheric magnetic fields in an integrated representation has enabled us to compare various types of measurements and estimate their stability. 相似文献
13.
The discovery of the possible existence of huge quasi-stationary envelopes around a number of hot Jupiters (i.e., with sizes appreciably exceeding their Roche lobes) and the need to correctly take into account their properties when interpreting observational data require a careful analysis of the main physical processes influencing their atmospheres. One important factor is the possibility that the planet has a magnetic field. It was shown earlier that the presence of even a modest dipolar magnetic field of a hot Jupiter (with a magnetic moment approximately 1/10 the magnetic moment of Jupiter) influences the properties of the planetary atmosphere, in particular, leading to expansion of the range of parameters for which a giant, quasi-closed envelope can form around the planet. It was also established that the presence of a planetary magnetic field reduced the mass-loss rate from the envelope, since matter flowing out from the inner Lagrange point moves perpendicular to the field lines. Three-dimensional magnetohydrodynamical (MHD) modeling on time scales appreciably exceeding the time for the formation of the envelope show that pulsations arise in the atmospheres of hot Jupiters possessing dipolar magnetic fields, with characteristic periods ~0.27Porb. This behavior is easy to understand physically, since even in the case of a spherical atmosphere, the continuous expansion of the ionized atmsphere of a hot Jupiter can lead to the accumulation of matter in regions bounded by closed field lines, and to the periodic rupture of the atmosphere beyond the magnetic field. In the case considered, when the system contains a giant envelope fed by a stream of matter from the inner Lagrange point, the presence of such pulsations gives rise to appreciable variations in the gas-dynamical structure of the flow. In particular, pulsations of the atmosphere lead to tearing off of part of the flow and sharp fluctuations in the size of the envelope, leading to variations in the envelope’s observational properties. 相似文献
14.
针对时间域脉冲瞬变电磁仪的PROTEM系统,结合其工作特点编制了一套系列应用软件,功能包括空间各点一次激励磁场强度计算、野外质量检查各种误差值统计计算、野外观测数据预处理及各种转换参量计算。应用该软件对某金属矿区的瞬变电磁资料进行了处理,结果表明程序运行有效、可靠,取得了较好的地质效果。 相似文献
15.
A. S. Arakcheev A. G. Zhilkin P. V. Kaigorodov D. V. Bisikalo A. G. Kosovichev 《Astronomy Reports》2017,61(11):932-941
The influence of the dipolar magnetic field of a “hot Jupiter” with the parameters of the object WASP-12b on the mass-loss rate from its atmosphere is investigated. The results of three-dimensional gas-dynamical and magnetohydrodynamical computations show that the presence of a magnetic moment with a strength of ~0.1 the magnetic moment of Jupiter leads to appreciable variations of the matter flow structure. For example, in the case of the exoplanet WASP-12b with its specified set of atmospheric parameters, the stream from the vicinity of the Lagrange point L1 is not stopped by the dynamical pressure of the stellar wind, and the envelope remains open. Including the effect of the magnetic field leads to a variation in this picture—the atmosphere becomes quasi-closed, with a characteristic size of order 14 planetary radii, which, in turn, substantially decreases the mass-loss rate by the exoplanet atmosphere (by~70%). This reduction of the mass-loss rate due to the influence of the magnetic fieldmakes it possible for exoplanets to form closed and quasi-closed envelopes in the presence of more strongly overflowing Roche lobes than is possible without a magnetic field. 相似文献
16.
Clay‐rich basins have undergone varying degrees of magnetic transformation during burial, affecting their ability to retain accurate records of Earth's dynamic magnetic field. We propose to bracket the magnetite‐out and pyrrhotite‐in temperatures in shales and slates from Taiwan and the Pyrenees by using a combination of low‐temperature magnetic transitions and geothermometers. For Tburial < 340°C, the magnetic assemblage is dominated by magnetite. Gradually with increasing burial temperature, the concentration of magnetite decreases to a few ppmv. We observe the magnetite‐out isograd at Tburial ~350°C. At Tburial >60°C and Tburial >340°C respectively, fine‐grained and coarse‐grained pyrrhotite develop. In the course of burial, a clay‐rich basin gradually loses its capability to retain a record of Earth's magnetic field. It is only during basin uplift, that coarse pyrrhotite might acquire a thermo remanent magnetization. Our results point out therefore highly contrasted magnetic properties and palaeomagnetic records between deeply buried basins and exhumed ones. 相似文献
17.
The results of 3D modeling of the formation of the accretion disks of intermediate polars are presented. A model with misaligned rotation axes of accretor and the orbit is onsidered, in which it is assumed that the white dwarf has a dipolar magnetic field with its symmetry axis inclined to the whitedwarf rotation and orbital axes. The computations show that, in the early stages of formation of the disk, the action of magnetic field is able to create the initial (seed) inclination of the disk. This inclination is then supported mainly by the dynamical pressure of the flow from the inner Lagrangian point L1. As themass of the disk increases, the inclination disappears. Under certain conditions, the disk inclination does not arise in systems with misaligned white-dwarf rotation and orbital axes. The influence of the magnetic field and asynchronous rotation of the accretor may result in the formation of spiral waves in the disk with amplitudes sufficient to be detected observationally. 相似文献
18.
Magnetic field singularities detected earlier as the self-intersection points of the F = 0 curves/surfaces are studied (where F is a certain differential factor calculated in the reference frame of the magnetic field at the given point); these singularities can be considered to be sources of the energy release in solar flares. Two types of such singularities, called transition points (TPs), have been found: the first type (TP1) corresponds to an intersection of the same type of components (terms) of the divergence of the magnetic field, and the second type (TP2) to the intersection of dissimilar components. There are some discontinuous spatial processes at these singularities, which produce jumps in the components of the divergence of the magnetic field (and their signs). TP2 singularities should result in much stronger effects than those resulting from TP1 singularities, which should give rise to the most powerful solar flares. The singularities studied are also compared with the null point of the magnetic field, when it exists. In particular, a model magnetic field containing a null point is considered. It is shown that the TP singularities do not coincide with the null point, but can be located in its vicinity; in the case considered, the TP1 singularity is located fairly close to the null point. 相似文献
19.
I. S. Savanov I. I. Romanyuk E. A. Semenko E. S. Dmitrienko 《Astronomy Reports》2011,55(12):1115-1122
We have analyzed polarization observations of the subdwarf Bal 09, which is one of a group of hybrid sdB stars that display
simultaneously both short- and long-period pulsations. Certain properties previously unknown for subdwarfs have been established
for Bal 09, such as variations of the pulsation amplitude of the main oscillation mode, rotational splitting of multiplets,
and variations of this splitting. Information about the stellar magnetic field must be considered if we wish to explain these
properties. New observational data enabling estimation of the longitudinal magnetic field of Bal 09 have been obtained on
the main stellar spectrograph of the 6-m telescope of the Special Astrophysical Observatory. Studies of the longitudinal component
of the magnetic field 〈B
z
〉 were carried out using a regression analysis. This method simultaneously yields estimates of the uncertainty in 〈B
z
〉. Test measurements of 〈B
z
〉 were carried out using the same method. For the star HD 158974, which has zero total magnetic field, the estimated longitudinal
magnetic field is 〈B
z
〉 = −4 ± 5 G. The standard magnetic field for the Ap star α
2CVn was measured to be −363 ± 17 G, in very good agreement with measurements in the literature. The estimated longitudinal
magnetic field for Bal 09 is 34 ± 63G—appreciably lower than values established earlier for six subdwarfs, ≈1.5 kG. The results
of the regression analysis for both individual spectral subranges and for intervals containing characteristic spectral features
did not indicate reliable detections of a magnetic field exceeding the uncertainties in 〈B
z
〉. The uncertainty in 〈B
z
〉, which was 60–80 G for the entire spectral range and 140–200 G for selected spectral intervals, leads to an estimated upper
limit on the longitudinal magnetic field 〈B
z
〉 for Bal 09. This estimate for 〈B
z
〉 can place observational constraints on theoretical explanations for the amplitude variations of the pulsations, rotational
splitting of multiplets, and possible variations of the internal structure of the star. 相似文献