With the increase in the coverage area of magnetotelluric data,three-dimensional magnetotelluric modeling in spherical coordinates and its differences with respect to traditional Cartesian modeling have gradually attr...With the increase in the coverage area of magnetotelluric data,three-dimensional magnetotelluric modeling in spherical coordinates and its differences with respect to traditional Cartesian modeling have gradually attracted attention.To fully understand the influence of the Earth’s curvature and map projection deformations on Cartesian modeling,qualitative and quantitative analyses based on realistic three-dimensional models need to be examined.Combined with five representative map projections,a type of model conversion method that transforms the original spherical electrical conductivity model to Cartesian coordinates is described in this study.The apparent resistivity differences between the spherical western United States electrical conductivity model and the corresponding five Cartesian models are then compared.The results show that the cylindrical equal distance map projection has the smallest error.A meridian convergence correction resulting from the deformation of the map projection is introduced to rotate the Cartesian impedance tensor from grid north to geographic north,which reduces differences from the spherical results.On the basis of the magnetotelluric field data,the applicability of the Cartesian coordinate system to western and contiguous United States models is quantitatively evaluated.Precise interpretations of the contiguous United States model were found to require spherical coordinates.展开更多
Materials such as Koch AH-70,basalt aggregate,limestone powder and graphite particles were used to prepare conductive asphalt concrete,which is a new type of multifunctional concrete.The mix proportion by weight was s...Materials such as Koch AH-70,basalt aggregate,limestone powder and graphite particles were used to prepare conductive asphalt concrete,which is a new type of multifunctional concrete.The mix proportion by weight was shown as follows.Fine aggregates (2.36-4.75 mm)∶fine aggregates (<2.36mm)∶limestone powder∶asphalt=120∶240∶14∶30.The content of added graphite particles ranged from 0% to 20%(by the weight of asphalt concrete).A conductive asphalt concrete with a resistivity around 10-10 3Ω·m was obtained.Special attention was paid to the effects of graphite content,graphite physical-chemical properties,asphalt content and temperature on the resistivity.Furthermore,an attempt was made to develop an electrically conductive model for asphalt concrete.展开更多
Seismic and magnetotelluric field campaigns carried out across the Himalaya and the Qinghai-Tibetan Plateau show mid-crustal low resistivity and low-velocity zones.Whether these anomalies indicate that there are molte...Seismic and magnetotelluric field campaigns carried out across the Himalaya and the Qinghai-Tibetan Plateau show mid-crustal low resistivity and low-velocity zones.Whether these anomalies indicate that there are molten zones present in the Tibet crust is a focus of geophysical and petrological research.Previous interpretations of MT data to infer melt fractions are often based on presumed electrical conductivity values of partial melt.Temperature,pressure,especially water content in the melt influences the melt conductivity and affects the inferred melt fractions in areas of Tibet.So accurate constraints are essential.In addition,a variety of equations have been proposed to model the conductivity of partially molten rocks in Tibetan crust.However,different rock electrical models relate to different lithological parameters of rocks.So we need to find an appropriate rock electrical model that can apply to Tibet crust.In this study,we use a general electrical conductivity model developed by the global fitting of experimental data in previous study and set up a range of temperature,pressure,and water content for five regions in Tibet.What’s more,using three widely used rock electrical models to figure out corresponding melt fractions in areas of Tibet.We find the most applicable rock electrical model in this region and know better about the distribution and morphology of medium in Tibetan crust.展开更多
基金the National Natural Science Foundation of China(Nos.42220104002,42104073,and 41630317).
文摘With the increase in the coverage area of magnetotelluric data,three-dimensional magnetotelluric modeling in spherical coordinates and its differences with respect to traditional Cartesian modeling have gradually attracted attention.To fully understand the influence of the Earth’s curvature and map projection deformations on Cartesian modeling,qualitative and quantitative analyses based on realistic three-dimensional models need to be examined.Combined with five representative map projections,a type of model conversion method that transforms the original spherical electrical conductivity model to Cartesian coordinates is described in this study.The apparent resistivity differences between the spherical western United States electrical conductivity model and the corresponding five Cartesian models are then compared.The results show that the cylindrical equal distance map projection has the smallest error.A meridian convergence correction resulting from the deformation of the map projection is introduced to rotate the Cartesian impedance tensor from grid north to geographic north,which reduces differences from the spherical results.On the basis of the magnetotelluric field data,the applicability of the Cartesian coordinate system to western and contiguous United States models is quantitatively evaluated.Precise interpretations of the contiguous United States model were found to require spherical coordinates.
文摘Materials such as Koch AH-70,basalt aggregate,limestone powder and graphite particles were used to prepare conductive asphalt concrete,which is a new type of multifunctional concrete.The mix proportion by weight was shown as follows.Fine aggregates (2.36-4.75 mm)∶fine aggregates (<2.36mm)∶limestone powder∶asphalt=120∶240∶14∶30.The content of added graphite particles ranged from 0% to 20%(by the weight of asphalt concrete).A conductive asphalt concrete with a resistivity around 10-10 3Ω·m was obtained.Special attention was paid to the effects of graphite content,graphite physical-chemical properties,asphalt content and temperature on the resistivity.Furthermore,an attempt was made to develop an electrically conductive model for asphalt concrete.
文摘Seismic and magnetotelluric field campaigns carried out across the Himalaya and the Qinghai-Tibetan Plateau show mid-crustal low resistivity and low-velocity zones.Whether these anomalies indicate that there are molten zones present in the Tibet crust is a focus of geophysical and petrological research.Previous interpretations of MT data to infer melt fractions are often based on presumed electrical conductivity values of partial melt.Temperature,pressure,especially water content in the melt influences the melt conductivity and affects the inferred melt fractions in areas of Tibet.So accurate constraints are essential.In addition,a variety of equations have been proposed to model the conductivity of partially molten rocks in Tibetan crust.However,different rock electrical models relate to different lithological parameters of rocks.So we need to find an appropriate rock electrical model that can apply to Tibet crust.In this study,we use a general electrical conductivity model developed by the global fitting of experimental data in previous study and set up a range of temperature,pressure,and water content for five regions in Tibet.What’s more,using three widely used rock electrical models to figure out corresponding melt fractions in areas of Tibet.We find the most applicable rock electrical model in this region and know better about the distribution and morphology of medium in Tibetan crust.
