In this study,we propose a three-dimensional(3D)forward modeling algorithm of surface-to-borehole transient electromagnetic(SBTEM)fields based on an unstructured vector fi nite-element method to analyze the characteri...In this study,we propose a three-dimensional(3D)forward modeling algorithm of surface-to-borehole transient electromagnetic(SBTEM)fields based on an unstructured vector fi nite-element method to analyze the characteristics of SBTEM responses for complex geoelectrical models.To solve the double-curl diff usion equation for the electric fi eld,we use an unstructured tetrahedral mesh to discretize the model domain and select the unconditionally stable backward Euler scheme to discretize the time derivative.In our numerical experiments,we use a grounded wire as a transmitting source.After validating the algorithm’s eff ectiveness,we first analyze the diffusion characteristics and detectability of the electromagnetic field.After that,we focus our attention on the distribution and the cause of zero bands for Ex and dBy/dt components with the hope of guiding future field surveys.Finally,by simulating diff erent models,we analyze the capability of the SBTEM method in detecting typical mineral veins so that we can provide a reference for mineral resource exploration in the deep earth.展开更多
This paper first elaborates the research situation and progress of Laplace characteristics and the eigenvalues value of graphs. The second is given an upper bound of characteristic value of a kind of special graph usi...This paper first elaborates the research situation and progress of Laplace characteristics and the eigenvalues value of graphs. The second is given an upper bound of characteristic value of a kind of special graph using the properties of similar matrices. At the same time, a new upper bound of Laplace characteristic values are given using properties of Laplace matrix and the similarity matrix, to improve the existing results. Then, we use the example of the upper bound of our results are more precise than some previous results. Finally the use Laplace non- zero eigenvalues of graph properties to give a bound expressions using the degree of square with a number of edges and the graph of the number, number of connected component expression map, it reflected the relationship between eigenvalues and the amount of Laplace.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos..42030806,41774125,41804098,41904104)the Key National Research Project of China(Grant No.2018YFC0603300).
文摘In this study,we propose a three-dimensional(3D)forward modeling algorithm of surface-to-borehole transient electromagnetic(SBTEM)fields based on an unstructured vector fi nite-element method to analyze the characteristics of SBTEM responses for complex geoelectrical models.To solve the double-curl diff usion equation for the electric fi eld,we use an unstructured tetrahedral mesh to discretize the model domain and select the unconditionally stable backward Euler scheme to discretize the time derivative.In our numerical experiments,we use a grounded wire as a transmitting source.After validating the algorithm’s eff ectiveness,we first analyze the diffusion characteristics and detectability of the electromagnetic field.After that,we focus our attention on the distribution and the cause of zero bands for Ex and dBy/dt components with the hope of guiding future field surveys.Finally,by simulating diff erent models,we analyze the capability of the SBTEM method in detecting typical mineral veins so that we can provide a reference for mineral resource exploration in the deep earth.
文摘This paper first elaborates the research situation and progress of Laplace characteristics and the eigenvalues value of graphs. The second is given an upper bound of characteristic value of a kind of special graph using the properties of similar matrices. At the same time, a new upper bound of Laplace characteristic values are given using properties of Laplace matrix and the similarity matrix, to improve the existing results. Then, we use the example of the upper bound of our results are more precise than some previous results. Finally the use Laplace non- zero eigenvalues of graph properties to give a bound expressions using the degree of square with a number of edges and the graph of the number, number of connected component expression map, it reflected the relationship between eigenvalues and the amount of Laplace.
