倾斜分层非均匀介质中磁偶极子场的数值分析

研究倾斜分层非均匀介质条件下磁偶极子源在介质空间的电磁响应 ,给出了场表达式和数值递推算法 ,提出了在大倾角条件下利用电阻率曲线划分界面和进行前向预测的方法 ,数值模拟和应用实践证明该方法是有效的 。

对覆盖层下三维导电异常体磁场影响关系的研究

在垂直磁偶极源和水平磁偶极源分别激励下 ,通过改变覆盖层的导电率 ,围岩的导电率和偶极源发射频率 ,研究相应的磁场变化规律 ,讨论围岩的性质 。

磁力勘探与岩性测深理论基础的对比

首先概括了岩性测深技术的理论基础和物性基础要点,强调电偶极子场是岩性测深技术的基本理论。然后通过电偶极子场与磁偶极子场的类比,以及岩性测深与磁力勘探的对比,提出了一条研究岩性测深技术理论基础及正演计算的思路。

A Magnetic Disturbance Compensation Method Based on Magnetic Dipole Magnetic Field Distributing Theory

The interference of carrier magnetic field to geomagnetic field has been a difficult problem for a long time,which influences on the deviation of navigation compass and the error of geomagnetic measurement. To increase the geomagnetic measuring accuracy required for the geomagnetic matching localization,the strategy to eliminate the effect of connatural and induced magnetic fields of carrier on the geomagnetic measuring accuracy is investigated. The magnetic-dipole's magnetic field distributing theory is used to deduce the magnetic composition in the position of the sensor installed on the carrier. A geomagnetic measurement model is established by using the measuring data with the ideal sensor. Considering the magnetic disturbance of carrier and the error of sensor,a geomagnetic measuring compensation model is built. This model can be used to compensate the errors of carrier magnetic field and magnetic sensor in any case and its parameters have clear or specific physical meaning. The experimented results show that the model has higher geomagnetic measuring accuracy than that of others.

Regional spatiotemporal variations of a nondipole magnetic field over the Chinese mainland and neighboring regions in millennial scale

Spatiotemporal variations of the nondipole （ND） magnetic field over the Chinese mainland and neighboring regions from 10000 BC to 1990 AD were analyzed using the latest global geomagnetic models CALS10K.1b, CALS3K.4, and IGRF 11. Moreover, for field sources, we investigated 2 n （n = 2 -10） pole ND fields and their energies. The results suggest that the study period can be divided into three. The intensity of the ND field has been mainly positive since 10000 BC and lasted almost 7500 years, then gradually decreased to negative in 2500 BC to 1500 AD, and finally sharply increased to positive. The anomaly areas of the ND field in East Asia took shape for n - 3, when the anomaly areas in East Asia were shaped into closed circles in the mainland. This suggests that the first three harmonic degrees account for most of the ND field. The energy of the ND field rapidly attenuates at the core mantle boundary and is stable at the surface.

IMPROVEMENT OF EXPRESSION FOR EXCITATION BY AN ELECTRIC DIPOLE IN GTEM CELL

On the basis of Wilson's work in which the vertical electric dipole is centrally located in GHz Transverse ElectroMagnetic (GTEM) cell, we deduce the expression for the field distribution excited by an electric dipole in the case that the dipole is not centrally located. It will be useful for EMC measurements using GTEM cell.

Electromagnetic fields from a horizontal electrical dipole buried in ocean

Marine controlled source electromagnetic signal could be used in mineral resource exploration,reservoir appraisal and communicative technique in ocean. It's necessary to study the electromagnetic generated by MCSEM. The propagation of the electromagnetic fields from a controlled source in the marine environment was studied with virtual interface method combined with discrete complex image method. Transmitter of finite length current source is approximated by dipole (HED) . A three-layered model is accepted,with sea water as intermediate conductive layer under air and a relatively high resistive seabed as basement,possibly containing a hydrogen layer of higher resistivity. The electromagnetic fields in whole space thus computed show that: (1) the spatial distribution of field component depends on its type; (2) inline Ex component is more sensitive to reservoir layer than that in broadside; (3) The airwave affects marine electromagnetic (MEM) exploration when sea water is relatively shallow; in the case of deep water MEM exploration,the airwave influence could be neglected; and (4) an appropriate frequency should be selected in order to balance the signal strength and electromagnetic induction effect.

Research on Distribution of Electric Dipole Field based on Applied Mathematics and Computer

The paper analyze the polarization of study dielectric that produced field by dipole, medium field plays an important role in electromagnetic wave radiation. The electric field expression for electric dipole electric field distribution in ordinary textbooks only give a special direction, This paper introduces in detail the formula of the electric dipole in the space of an arbitrary point excitation electric field, and use computer sottware to simulate the distribution pattern of electric dipole, and gives some typical figures for reference.

Dramatic transition between electric and magnetic rotations in ^(106)Ag

The lifetimes for the states of magnetic dipole band in106Ag have been measured using the Doppler-shift attenuation method via the reaction of100Mo(11B,5n)106Ag at a beam energy of 60 MeV.The reduced transition strengths of the magnetic dipole band,the B(M1)/B(E2)ratios together with the signature of the level energy as a function of angular momentum for the positive parity states of106Ag show that a drastic change of excitation mode,that is,from electric rotation to magnetic rotation,occurs within one unit of spin at around Iπ=12+.Theoretical calculations based on the triaxial projected shell model consistently reproduce the experimental data and provide an explanation on the nature of observed phenomena such that the dynamical drift of the rotational axis suddenly from the principal axis to the tilted one,along the positive parity bands of106Ag.

A study on variations of non-dipole magnetic field over Chinese mainland during 2000 BC to 1990 AD

We calculated and analyzed variation of the non-dipole(ND)magnetic field at the millennium scale over the Chinese mainland during 2000 BC–1900 AD using the newest global geomagnetic model,CALS3K.4(3K.4).The newest-generation IGRF(IGRF11)was used to verify the results.Taking component Z for example,we calculated and analyzed the distribution and annual change rates of the ND field during 1900–1990 AD every 5 yr,using two models.To thoroughly analyze the contributions of field sources,quadrupole and octupole fields,and others within the ND field at the surface and core-mantle boundary(CMB)were investigated.Results show that there were three main variation phases of the field during the period 2000BC–1900 AD.The mean amplitude roughly reflected the ND field because of the distribution and variation of that field,corresponding somewhat to the mean amplitude change.A magnetic anomaly of the ND field over East Asia(EA)first emerged in 1682 AD,and its extreme intensity had increased a total of 15276.95 nT by 1900 AD.Its location moved continuously southeastward after 1690 AD.The asymmetry between location and intensity of extreme points over EA,particularly during1740–1760 AD,indicates irregularity of fluid motion inside the outer core.Mean annual changes of Z are generally divided into four phases,which first oscillated between 2000 and 800 BC,then increased,decreased and increased in the periods 800BC–300 AD,300–900 AD and 900–1900 AD,respectively.The intensity of mean annual change increased a total of 22.87nT/yr.Anomaly extreme locations based on 3K.4 and IGRF11 over EA centered around 44°N and 103°E for degree(n)greater than 5,and intensities continuously increased with n.During 2000 BC–1990 AD,ND energy of Z at the surface and CMB had decreased in total by 18.29%and 23.23%,respectively.The field source of 26–210 pole fields are more or less affected by the lithospheric field.Energies of higher degree at the surface attenuate by almost 99%compared with CMB,but mean attenuation speeds of the low-degree ND field are faster than high-degree,which implies that the low-degree ND field has a deeper source.

Dynamics of Charged Particles Around a Magnetized Black Hole with Pseudo–Newtonian Potential

The linear stability of equilibria of charged particles moving near a compact object with a dipole magnetic field and a pseudo-Newtonian potential is analyzed detalledly. An optimal fourth-order force gradient symplectic method, as a global symplectic integrator that can simultaneously solve both the equations of motion and the variational equations, is used to calculate fast Lyapunov indicators. In this way, dynamical structures are described, and parameter domains for causing chaos are found.

Chain formation in a monolayer of dipolar hard spheres under an external field

The phase behavior of a monolayer of dipolar hard spheres under an external field, which makes all dipoles of the monolayer orientate along its direction, is investigated. Using integral equation theory in the reference hypemetted chain （RHNC） approximation we calculate the correlation functions, which are used to obtain the response matrix of grand potential with respect to density fluctuations. The smallest eigenvalue of this response matrix determines the stability of the monolayer. When the smallest eigenvalue approaches zero, the monolayer becomes unstable and the corresponding eigenvector characterizes this instability. At dilute densities, with decreasing temperature the dipoles of the monolayer begin to form chains and simultaneously condensate. At medium and high densities, however, the dipoles of the monolayer have a stronger tendency to form dipolar chains with decreasing temperature and there is no condensation. The part of specific heat related to potential energy is investigated and found to increase sharply near the temperature of dipolar chain formation. This is in accordance with a sharp decrease in potential energy induced by the formation of a dipolar chain.