In this paper, we present a magnetocardiogram （MCG） simulation study using the boundary element method （BEM） and based on the virtual heart model and the realistic human volume conductor model. The different contr...In this paper, we present a magnetocardiogram （MCG） simulation study using the boundary element method （BEM） and based on the virtual heart model and the realistic human volume conductor model. The different contributions of cardiac equivalent source models and volume conductor models to the MCG are deeply and comprehensively investigated. The single dipole source model, the multiple dipoles source model and the equivalent double layer （EDL） source model are analysed and compared with the cardiac equivalent source models. Meanwhile, the effect of the volume conductor model on the MCG combined with these cardiac equivalent sources is investigated. The simulation results demonstrate that the cardiac electrophysiological information will be partly missed when only the single dipole source is taken, while the EDL source is a good option for MCG simulation and the effect of the volume conductor is smallest for the EDL source. Therefore, the EDL source is suitable for the study of MCG forward and inverse problems, and more attention should be paid to it in future MCG studies.展开更多
A sea temperature data assimilation system forthe China Seas and adjacent areas is developed based on anested regional ocean circulation model and variational op-timal interpolation assimilation method. A 12-year assi...A sea temperature data assimilation system forthe China Seas and adjacent areas is developed based on anested regional ocean circulation model and variational op-timal interpolation assimilation method. A 12-year assimila-tion experiment is performed by using the observationaltemperature profiles from World Ocean Database 1998(WOD98) and ECMWF reanalysis surface wind stress. Ex-perimental results indicate that the variational schemeshows good skill in assimilating the observed sea temperatureinto a regional ocean circulation model. Compared withsimulation alone, the sea temperature data assimilation sig-nificantly improves the performance of a regional oceanmodel and obtains comprehensive description of the circula-tions in the China Seas and adjacent areas. Assimilation re-sults, such as the strength and flowing axis of the Kuroshio,Yellow Sea Cold Water Mass and its corresponding horizon-tal circulation in summer and dipole eddies in the SouthChina Sea in the late summer/early autumn and the east-ward jet between them, are well consistent with the observedevidences.展开更多
Based on the electric dipole theory, the coupled field distribution of pulse electric field (PEF) with electric dipole field around the cluster in superheated molten alloy is simulated under the effect of PEF. For the...Based on the electric dipole theory, the coupled field distribution of pulse electric field (PEF) with electric dipole field around the cluster in superheated molten alloy is simulated under the effect of PEF. For the difference of electro-migration, the atom of solute and solution will accumulate around the cluster, and then the smaller cluster may reorganize and grow up under the action of the coupled field. We also apply the electrostatic induction theory to analyze the bearing behavior of the half side of the cluster. The bigger the cluster is, the stronger the electrostatic force is, therefore, the bigger cluster's stability is weak apparently. The study indi- cates that the cluster in the superheated molten has the homogeneous tendency under the effect of PEF.展开更多
A modeling tool for simulating three-dimensional land frequency-domain controlled-source electromagnetic surveys,based on a finite-element discretization of the Helmholtz equation for the electric fields,has been deve...A modeling tool for simulating three-dimensional land frequency-domain controlled-source electromagnetic surveys,based on a finite-element discretization of the Helmholtz equation for the electric fields,has been developed.The main difference between our modeling method and those previous works is edge finite-element approach applied to solving the three-dimensional land frequency-domain electromagnetic responses generated by horizontal electric dipole source.Firstly,the edge finite-element equation is formulated through the Galerkin method based on Helmholtz equation of the electric fields.Secondly,in order to check the validity of the modeling code,the numerical results are compared with the analytical solutions for a homogeneous half-space model.Finally,other three models are simulated with three-dimensional electromagnetic responses.The results indicate that the method can be applied for solving three-dimensional electromagnetic responses.The algorithm has been demonstrated,which can be effective to modeling the complex geo-electrical structures.This efficient algorithm will help to study the distribution laws of3-D land frequency-domain controlled-source electromagnetic responses and to setup basis for research of three-dimensional inversion.展开更多
Unlike Earth,Mars lacks a global dipolar magnetic field but is dominated by patches of a remnant crustal magnetic field.In 2021,the Chinese Mars Rover will land on the surface of Mars and measure the surface magnetic ...Unlike Earth,Mars lacks a global dipolar magnetic field but is dominated by patches of a remnant crustal magnetic field.In 2021,the Chinese Mars Rover will land on the surface of Mars and measure the surface magnetic field along a moving path within the possible landing region of 20°W-50°W,20°N-30°N.One scientific target of the Rover is to monitor the variation in surface remnant magnetic fields and reveal the source of the ionospheric current.An accurate local crustal field model is thus considered necessary as a field reference.Here we establish a local crust field model for the candidate landing site based on the joint magnetic field data set from Mars Global Explorer(MGS)and Mars Atmosphere and Volatile Evolution(MAVEN)data combined.The model is composed of 1,296 dipoles,which are set on three layers but at different buried depths.The application of the dipole model to the joint data set allowed us to calculate the optimal parameters of their dipoles.The calculated results demonstrate that our model has less fitting error than two other state-of-the art global crustal field models,which would indicate a more reasonable assessment of the surface crustal field from our model.展开更多
The properties of the modified surface of SnO2(110) with benzoic acid (Y-C6H4-COOH: Y is para position relative to -COOH group) derivatives were investigated using density functional theory. Zehner et al. mentioned th...The properties of the modified surface of SnO2(110) with benzoic acid (Y-C6H4-COOH: Y is para position relative to -COOH group) derivatives were investigated using density functional theory. Zehner et al. mentioned that the modification of surface dipole moment made it possible to tune the work function of the system. The experiment of Ganzorig et al. showed that there was a linear relationship between the dipole moment of the binding molecule and the work function change of the system using the modified surface of indium-tin oxide (ITO) with some benzoic acid derivatives. To elucidate the relation between the dipole moment of the molecule and the work function change, we investigated the modified surface of SnO2(110) using Sn7O14 cluster model which was embedded in the fixed point charges. On the modification of the surface, benzoic acid derivatives were bound to SnO2 surface. By changing the terminal group of benzoic acid with H, Cl, F, CF3 and CCl3, the work function changed and the dipole moment of the binding molecules of the modified SnO2(110) were evaluated. The results showed that there was a linear relationship between the dipole moment of the binding molecules and the work function changed. From this relation, the average value of the dipole moments of Sn-OOC linkage at the surface was also evaluated.展开更多
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 MCSE...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.展开更多
基金supported by the State Key Development Program for Basic Research of China (Grant Nos. 2007CB512100 and2006CB601007)the National Natural Science Foundation of China (Grant No. 10674006)+2 种基金the National High Technology Research and Development Program of China (Grant No. 2007AA03Z238)China Postdoctoral Science Foundation (Grant No. 20090461376)the Fundamental Research Funds for the Central Universities (Grant No. KYJD09001)
文摘In this paper, we present a magnetocardiogram （MCG） simulation study using the boundary element method （BEM） and based on the virtual heart model and the realistic human volume conductor model. The different contributions of cardiac equivalent source models and volume conductor models to the MCG are deeply and comprehensively investigated. The single dipole source model, the multiple dipoles source model and the equivalent double layer （EDL） source model are analysed and compared with the cardiac equivalent source models. Meanwhile, the effect of the volume conductor model on the MCG combined with these cardiac equivalent sources is investigated. The simulation results demonstrate that the cardiac electrophysiological information will be partly missed when only the single dipole source is taken, while the EDL source is a good option for MCG simulation and the effect of the volume conductor is smallest for the EDL source. Therefore, the EDL source is suitable for the study of MCG forward and inverse problems, and more attention should be paid to it in future MCG studies.
文摘A sea temperature data assimilation system forthe China Seas and adjacent areas is developed based on anested regional ocean circulation model and variational op-timal interpolation assimilation method. A 12-year assimila-tion experiment is performed by using the observationaltemperature profiles from World Ocean Database 1998(WOD98) and ECMWF reanalysis surface wind stress. Ex-perimental results indicate that the variational schemeshows good skill in assimilating the observed sea temperatureinto a regional ocean circulation model. Compared withsimulation alone, the sea temperature data assimilation sig-nificantly improves the performance of a regional oceanmodel and obtains comprehensive description of the circula-tions in the China Seas and adjacent areas. Assimilation re-sults, such as the strength and flowing axis of the Kuroshio,Yellow Sea Cold Water Mass and its corresponding horizon-tal circulation in summer and dipole eddies in the SouthChina Sea in the late summer/early autumn and the east-ward jet between them, are well consistent with the observedevidences.
基金Supported jointly by the National Natural Science Foundation of China (Grant No. 50674054)the College Key Laboratory Open Fund of Liaoning Province (Grant No. 200516203)
文摘Based on the electric dipole theory, the coupled field distribution of pulse electric field (PEF) with electric dipole field around the cluster in superheated molten alloy is simulated under the effect of PEF. For the difference of electro-migration, the atom of solute and solution will accumulate around the cluster, and then the smaller cluster may reorganize and grow up under the action of the coupled field. We also apply the electrostatic induction theory to analyze the bearing behavior of the half side of the cluster. The bigger the cluster is, the stronger the electrostatic force is, therefore, the bigger cluster's stability is weak apparently. The study indi- cates that the cluster in the superheated molten has the homogeneous tendency under the effect of PEF.
基金Projects(41674080,41674079)supported by the National Natural Science Foundation of China
文摘A modeling tool for simulating three-dimensional land frequency-domain controlled-source electromagnetic surveys,based on a finite-element discretization of the Helmholtz equation for the electric fields,has been developed.The main difference between our modeling method and those previous works is edge finite-element approach applied to solving the three-dimensional land frequency-domain electromagnetic responses generated by horizontal electric dipole source.Firstly,the edge finite-element equation is formulated through the Galerkin method based on Helmholtz equation of the electric fields.Secondly,in order to check the validity of the modeling code,the numerical results are compared with the analytical solutions for a homogeneous half-space model.Finally,other three models are simulated with three-dimensional electromagnetic responses.The results indicate that the method can be applied for solving three-dimensional electromagnetic responses.The algorithm has been demonstrated,which can be effective to modeling the complex geo-electrical structures.This efficient algorithm will help to study the distribution laws of3-D land frequency-domain controlled-source electromagnetic responses and to setup basis for research of three-dimensional inversion.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDA17010201)the National Natural Science Foundation of China(grants nos.41922031,41774188,41525016,and 41621063).
文摘Unlike Earth,Mars lacks a global dipolar magnetic field but is dominated by patches of a remnant crustal magnetic field.In 2021,the Chinese Mars Rover will land on the surface of Mars and measure the surface magnetic field along a moving path within the possible landing region of 20°W-50°W,20°N-30°N.One scientific target of the Rover is to monitor the variation in surface remnant magnetic fields and reveal the source of the ionospheric current.An accurate local crustal field model is thus considered necessary as a field reference.Here we establish a local crust field model for the candidate landing site based on the joint magnetic field data set from Mars Global Explorer(MGS)and Mars Atmosphere and Volatile Evolution(MAVEN)data combined.The model is composed of 1,296 dipoles,which are set on three layers but at different buried depths.The application of the dipole model to the joint data set allowed us to calculate the optimal parameters of their dipoles.The calculated results demonstrate that our model has less fitting error than two other state-of-the art global crustal field models,which would indicate a more reasonable assessment of the surface crustal field from our model.
文摘The properties of the modified surface of SnO2(110) with benzoic acid (Y-C6H4-COOH: Y is para position relative to -COOH group) derivatives were investigated using density functional theory. Zehner et al. mentioned that the modification of surface dipole moment made it possible to tune the work function of the system. The experiment of Ganzorig et al. showed that there was a linear relationship between the dipole moment of the binding molecule and the work function change of the system using the modified surface of indium-tin oxide (ITO) with some benzoic acid derivatives. To elucidate the relation between the dipole moment of the molecule and the work function change, we investigated the modified surface of SnO2(110) using Sn7O14 cluster model which was embedded in the fixed point charges. On the modification of the surface, benzoic acid derivatives were bound to SnO2 surface. By changing the terminal group of benzoic acid with H, Cl, F, CF3 and CCl3, the work function changed and the dipole moment of the binding molecules of the modified SnO2(110) were evaluated. The results showed that there was a linear relationship between the dipole moment of the binding molecules and the work function changed. From this relation, the average value of the dipole moments of Sn-OOC linkage at the surface was also evaluated.
基金Supperted by project of the National Science Foundation of China(No.40874050)
文摘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.
