Changsha 5D Geo survey and Technical Co.

Changsha, China

Changsha 5D Geo survey and Technical Co.

Changsha, China
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Lai L.-B.,Central South University | Xi Z.-Z.,Central South University | Wang H.,Central South University | Hou H.-T.,Central South University | And 4 more authors.
Wutan Huatan Jisuan Jishu | Year: 2014

The integral equation method for solving large sparse matrix controls 3D transient electromagnetic forward modeling for near region of a line source in speed. It is not only saving memory and computing time, but also reducing the discrete matrix condition number for improving the calculation speed and accuracy by the method of system iterative that we take the anomaly structure as a whole system, the substructure from subsystems within themselves and solve the various abnormal body alone to establish the relationship between the subsystem, thus get the whole system. This method is correct by comparison with the analytical solution. The secondary horizontal electric field and vertical magnetic field transient response calculation results of the simple and complex three-dimensional body show that: the secondary horizontal electric field value reflects the electrical characteristics of three-dimensional abnormal body, its extremun corresponding to left and right boundary of the abnormal body; vertical magnetic field response reflects the longitudinal resolution of abnormal body, curves increasing with offset slowly.


Xi Z.-Z.,Central South University | Zhu W.-G.,Central South University | Zhang D.-J.,Changsha 5D Geo survey and Technical Co. | Zhang L.-L.,Bureau of Mineral Resources | And 2 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

When the enrichment iron ore is buried more than 500 m, it is difficult to achieve the longitudinal resolution of iron ore abnormalities by using audio-frequency magnetotelluric (AMT) method directly. For this reason, based on the geological factors of the ore genesis, metallogenic environment, ore controlling space, and so on, the geological model was made and then the electrical model was set up, which was used to achieve the aim of indirect ore prospection by AMT method. The prospecting tests results in Qijiang-type iron deposit and Ningxiang-type iron deposit prove that the AMT method can deterimine prespecting mark, ore-bearing strata, ore-bearing structure and so on. So, indirectly detect deep-buried rich iron ore.


Chen X.-P.,Central South University | Song G.,Changsha 5D Geo survey and Technical Co. | Zhou S.,Changsha 5D Geo survey and Technical Co. | Xi Z.-Z.,Central South University | Wang H.,Central South University
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

Magnetic field induction sensors have been the bottleneck in the development of electromagnetic devices in China. In abroad, the natural geomagnetic variations are mainly measured by magnetic field induction sensors in magnetotelluric methods. According to the characteristics of the natural geomagnetic variations in audio-frequency band and the basic principle of magnetic field induction sensors, the structure of core, coil winding and the resonant frequency of the sensor were designed. With the magnetic flux negative feedback and frequency compensation, the frequency band is extended and the flat resulting amplitude-frequency response is obtained in the frequency band of 1 Hz-9.8 kHz with the deviation no more than ±1.5 dB. It can be used in audio-frequency magnetotelluric sounding.


Tan S.-C.,Central South University | Wang H.,Central South University | Xi Z.-Z.,Central South University | Zhou S.,Changsha 5D Geo survey and Technical Co.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

The transient electromagnetic method was only used to interpret vertical component for a long time. And for this reason, there exist some problems, such as information deficiency, low exploration precision and inadequate explaining ability in productive activities and exploration. Therefore, this work calculates the transient electromagnetic field by using eigencurrent model and Galerkin method, and defines a function to get the ratio of the vertical component and horizontal component and gives explanations based on the ratio. In the mean time, the relevant physical simulation experiments were carried out. The results show that the deficiency of single-component explanation can be avoided by fully using three components in explanations through this method, and the position and tendency of the low-resistance plane can be simply judged.


Li R.-X.,Central South University | Zhang D.-J.,Changsha 5D Geo survey and Technical Co. | Huang L.,Changsha 5D Geo survey and Technical Co. | Xi Z.-Z.,Central South University | And 2 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

To solve those problems existed in rectangular grid and triangular mesh method, an inverse growth algorithm for the geophysical data was presented. According to the characteristics of discrete geophysical data, the data boundary was extracted first, and then triangular mesh was generated from outside to inside by using the boundary as the basis. This algorithm was used to triangulation and visualization analysis of an EH4 sounding profile data. The result states that, high-quality irregular triangular mesh can be generated automatically, and the data boundary is fitted easily and accurately, a good foundation is provided for data visualization and data processing.


Wang H.,Central South University | Jiang H.,Central South University | Wang L.,Changsha 5D Geo survey and Technical Co. | Xi Z.,Central South University | Zhang D.,Changsha 5D Geo survey and Technical Co.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2015

The artificial neural network (ANN) was studied to improve the magnetotelluric inversion operation efficiency and calculation accuracy. The input of neural network was apparent resistivity of the known models, and the output of neural network was the geoelectric parameters. The neural network was trained by back propagation algorithm, which contains the methods of information forward propagation and error back propagation. The best weight of network calculated by the training work was used to test the unknown model patterns, which is the inversion process. The networks for two-layer model and three-layer model were set up respectively. The results show that the neural network inversion is feasible and effective. ©, 2015, Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology). All right reserved.


Xi Z.-Z.,Central South University | Xu P.-Y.,Central South University | Long X.,Changsha 5D Geo survey and Technical CO. | Wang H.,Central South University | And 2 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2011

The orthogonal horizontal magnetic dipole source simulates the natural electromagnetic field well, it conveniently realizes the tensor survey of controlled electromagnetic source in a high frequency band. The field distribution of orthogonal horizontal magnetic dipole source in homogeneous isotropic medium is computed. The result indicates that the horizontal components of the electromagnetic field show a belt of relatively low value in each quadrant, the scalar apparent resistivity shows a distortion belt in the same position, while the tensor apparent resistivity doesn't show distortion belt; The tensor apparent resistivity is low in the near zone and high in the transition region, and tends to the true value in the far zone. Field experiment was carried out to confirm the numerical result. As the true resistivity of test location is unknown, the test result of orthogonal horizontal magnetic dipole source is contrasted to that of the natural electromagnetic field. The result shows that, similar to the electric dipole source, the field of orthogonal horizontal magnetic dipole source also has a near zone, a transition zone, and a far zone. In the far zone, the relative distance of the source and survey station has no effect on the measurement result, namely, in the far zone measurement can be done in any azimuth. So the influence of separation should be considered to ensure that the measuring is in the far zone.


Zhou S.,Central South University | Zhou S.,Changsha 5D Geo survey and Technical Co. | Xi Z.-Z.,Central South University | Song G.,Changsha 5D Geo survey and Technical Co. | And 3 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2012

By analyzing the electrical characteristics of the deep-sea hydrothermal sulfide ores, an electrical model was established. The transient electromagnetic (TEM) response to the model was computed according to the theory of the TEM response in full-space, which provided a basis for the deep-sea towed TEM system. The results show that the TEM responses to models in deep-sea are similar in the curve shape to that on the earthground, while the amplitude increases significantly. The towing height seriously reduces the TEM response to the mineralized low-resistivity layer. The abnormal response delays and decreases rapidly when the towing height increases. It is difficult to distinguish the response when the height is more than 50 m. Generally, it is possible to distinguish the response to the mineralized low-resistivity layer within 1-100 m window.

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