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There are 16 papers published in subject: > since this site started. |
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1. Issues in stochastic modeling of ground motions based on analytical phase spectrum | |||
ZENG Cheng,SUN Xiaodan,LI Yongheng | |||
Earth Science 25 May 2016 | |||
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Abstract:In this paper, stochastic modeling technique based on analytical phase spectrum was studied. The analytical displacement response to a shear dislocation source in infinite homogeneous space was used to extract analytical phase spectrum. The analytical phase spectrum was used to replace the random phase spectrum so that the spectrum of the simulated motion is related to the property of propagation medium and the source-site geometry. Two issues, the simplification of numerical integration and the computation of sub-source rise time, were discussed. The results show that: when the sub-source size is smaller than 1km, the numerical integration could be simplified by multiplying the sub-source area to the displacement from point dislocation source; unreasonable sub-source rise time may be deduced if letting sub-source rise time propotional to sub-source dislocation.The approach was validated using the observed data of the 1994 Northridge earthquake. The validation shows a good match between the simulated and observed data in terms of waveform and response spectrum. | |||
TO cite this article:ZENG Cheng,SUN Xiaodan,LI Yongheng. Issues in stochastic modeling of ground motions based on analytical phase spectrum[OL].[25 May 2016] http://en.paper.edu.cn/en_releasepaper/content/4693864 |
2. 2D inversion of frequency-domain electromagnetic data generated by line current source | |||
TONG Xiaozhong,CAO Chuanghua,LIU Jianxin | |||
Earth Science 18 November 2015 | |||
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Abstract:The inversion of electromagnetic data is an inherently non-unique and unstable problem due to the data noises and incomplete data coverage, which means different geo-electrical models could fit the observed data at the same level. A stable solution of an ill-posed inverse problem can be obtained by the regularization methods in which some desired structure are imposed to stabilize the inverse problem. We have developed an algorithm to invert frequency-domain electromagnetic data generated by a line current source for a 2D model of the earth. To stabilize the inversion, we adopt a smoothness-constraint approach for the model parameters and adjust the regularization parameter objectively using a adaptive regularization parameter technique. For calculating the sensitivities using any of the accurate methods will be very time-consuming, we applied the adjoint-equation approximate method. By means of the numerical examples using synthetic data, we have demonstrated that the inversion method can be effectively to reconstruct the subsurface resistivity structure. | |||
TO cite this article:TONG Xiaozhong,CAO Chuanghua,LIU Jianxin. 2D inversion of frequency-domain electromagnetic data generated by line current source[OL].[18 November 2015] http://en.paper.edu.cn/en_releasepaper/content/4662949 |
3. The mechanism of seismo-magnetic anomaly before the earthquake and its role in earthquake prediction | |||
Chu Qingzhong,Li Hui,Wu Ze,Liang Wubin,Chen Xiaozhe,Shi Peibing | |||
Earth Science 25 September 2014 | |||
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Abstract:In this paper introduces three aspects of content: cause of earthquake; magnetic anomaly analysis before the earthquake; the relationship of magnetic anomaly and earthquake magnitude. Through the research of WenChuan earthquake, introduce seismo-magnetic anomaly detailedly. This paper also introduces the application of wavelet analysis in interference rejection and Date Processing, provides effective method for seismo-magnetic observation. | |||
TO cite this article:Chu Qingzhong,Li Hui,Wu Ze, et al. The mechanism of seismo-magnetic anomaly before the earthquake and its role in earthquake prediction[OL].[25 September 2014] http://en.paper.edu.cn/en_releasepaper/content/4609376 |
4. Medium effect on the characteristics of the coupled seismic and electromagnetic signals | |||
HUANG Qinghua,ZHANG Dan | |||
Earth Science 01 July 2014 | |||
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Abstract:The recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results based on the above method showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals induced by a layered medium structure model is more complicated than that induced by a simple uniform medium structure model. The seismic and electromagnetic signals showed different responses to the variations of medium properties such as salinity and viscosity. | |||
TO cite this article:HUANG Qinghua,ZHANG Dan. Medium effect on the characteristics of the coupled seismic and electromagnetic signals[OL].[ 1 July 2014] http://en.paper.edu.cn/en_releasepaper/content/4602909 |
5. Numerical simulation of the electromagnetic-wave-induced shear horizontal wave logging for measuring shear velocity in a porous formation | |||
Guan Wei,Cui Naigang,Hu Hengshan | |||
Earth Science 03 March 2014 | |||
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Abstract:A method is proposed for measuring the shear wave velocity by using the electromagnetic-wave-induced shear horizontal (SH) wave logging. In this method, a horizontal current loop that exits the transverse electric wave is located in the borehole and the induced SH wave is received at the borehole wall due to the electrokinetic effect in porous formation. Numerical simulations of the logs are implemented in different fluid-saturated porous formations, and the shear wave velocities are directly extracted from the simulated full waveforms. Compared to the acoustic logging, the method is not restricted by the formation and the source frequency. | |||
TO cite this article:Guan Wei,Cui Naigang,Hu Hengshan. Numerical simulation of the electromagnetic-wave-induced shear horizontal wave logging for measuring shear velocity in a porous formation[OL].[ 3 March 2014] http://en.paper.edu.cn/en_releasepaper/content/4588598 |
6. Sensitivity analysis of different IP models based on magnetotelluric method | |||
Rui Tang,Peng Yu,Xu Zhang,Yang Xiang | |||
Earth Science 18 November 2013 | |||
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Abstract:The IP effect incorporated in MT signal is a tough question for its complicated situation in separating one from another when dealing with practical exploration. There are also many models proposed by some researchers to approximately describe the induced polarization effect, and yet which model is proper and effective when using in MT is still unknown. A main objective of this study is to choose a proper IP model suit for manipulation in MT forward and inversion by calculating and analyzing the sensitivity and integrated sensitivity of apparent resistivity to the different IP model parameters. Based on the analysis of these figures, we provide a few references in the selection IP model when applying extracting of the IP effect from MT data. | |||
TO cite this article:Rui Tang,Peng Yu,Xu Zhang, et al. Sensitivity analysis of different IP models based on magnetotelluric method[OL].[18 November 2013] http://en.paper.edu.cn/en_releasepaper/content/4568685 |
7. A fast automatic interpretation of 3D potential-field data | |||
ZhangXu,YuPeng,ChenXiao,Tang Rui,XiangYang | |||
Earth Science 07 November 2013 | |||
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Abstract:Gravity and magnetic data have been extensively used in the interpretation of geologic features, such as location, depth and geological structures. We have presented two improved technique for inversing the source parameters. First we introduce a new filter called sine angle, which is useful to improve the resolution of the weak response of deep-source. We also develop a simple approach to determine both the depth and source geometry. We have generalized the approach for gravity field, especially for contact of the gravity and multiple sources with different geometries. The feasibility and stability of our method are demonstrated on synthetic data. | |||
TO cite this article:ZhangXu,YuPeng,ChenXiao, et al. A fast automatic interpretation of 3D potential-field data[OL].[ 7 November 2013] http://en.paper.edu.cn/en_releasepaper/content/4568602 |
8. MT Regularized inversion based on the minimum support gradient stabilizing functional | |||
XIANG Yang,YU Peng,ZHANG Xu,TANG Rui,ZHAO Chongjin | |||
Earth Science 07 November 2013 | |||
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Abstract:Magnetotelluric (MT) inversion is ill-posed. Normally we use regularization methods by adding stabilizing functional to get a stable solution. Previous study of traditional smoothness constraint model could not properly invert sharp electrical boundary, while the inversion results of stabilizers suitable for sharp boundary are heavily depend on focusing parameters. In this paper, we construct a new minimum support gradient stabilizing functional which combines smooth and sharp boundary inversion together, and apply it in the unified form of regularized inversion objective functional. Through the comparisons of 1-D, 2-D inversion results between this new stabilizer and other common stabilizers, show that this new minimum support gradient stabilizer could better delineate the sharp electrical boundary than traditional stabilizers while ensuring a stable inversion result in MT regularized inversion. | |||
TO cite this article:XIANG Yang,YU Peng,ZHANG Xu, et al. MT Regularized inversion based on the minimum support gradient stabilizing functional[OL].[ 7 November 2013] http://en.paper.edu.cn/en_releasepaper/content/4568592 |
9. Application of ensemble empirical mode decomposition for analyzing geoelectric field during storm time | |||
LIU Jin,SUN Weihuai,LIU Lu | |||
Earth Science 15 August 2013 | |||
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Abstract:In this paper, we preliminarily apply the Ensemble Empirical Mode Decomposition (EEMD) technique for decomposing geomagnetic signals in July, 2012, for extracting the major storm-time fluctuations as a combining of intrinsic oscillatory modes (IMFs). By estimating the induced geoelectric field by PWM method, it is comfirmed that the high-frequency (0.01-1Hz) geomagnetic variation play a main role in inducing geoelectric field on the earth surface. The results indicates that the combination of EEMD and Hilbert-Transform is indeed an efficient method for analyzing the multi-scale features of geomagnetic storm-time disturbance. | |||
TO cite this article:LIU Jin,SUN Weihuai,LIU Lu. Application of ensemble empirical mode decomposition for analyzing geoelectric field during storm time[OL].[15 August 2013] http://en.paper.edu.cn/en_releasepaper/content/4554903 |
10. Detection of LNAPL contamination with GPR and resistivity surveys | |||
LU Qi,LIU Cai,FENG Xuan,LI Hongli,LIANG Wenjing,ZOU Lilong | |||
Earth Science 25 November 2011 | |||
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Abstract:This paper presents the effectiveness of electromagnetic (EM) exploration techniques for detecting near-surface soil contaminants. Field work has been done at a former industrial site containing light non-aqueous phase liquid (LNAPL) in soils. The experiment shows that a combination of ground penetrating radar (GPR) and electrical resistivity can provide an effective means of mapping subsurface contamination. Soil cores sampled in the three boreholes clearly indicate that the concentration of total petroleum hydrocarbons (TPH) has an inverse relation to the relative dielectric constant and a direct proportional correlation with the electrical resistivity.GPR data have high spatial resolution and enable us to image the shallow subsurface stratigraphy, although its depth of penetration is greatly limited in a conductive region. The electrical resistivity method is effective to obtain the resistivity structure associated with the subsurface stratigraphy and the contamination zone. Three-dimensional GPR and resistivity images are constructed to map LNAPL contamination which is illustrated by the decreased radar signal amplitude and increased resistivity. | |||
TO cite this article:LU Qi,LIU Cai,FENG Xuan, et al. Detection of LNAPL contamination with GPR and resistivity surveys[OL].[25 November 2011] http://en.paper.edu.cn/en_releasepaper/content/4451870 |
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