The equivalent source(ES)method in the spherical coordinate system has been widely applied to processing,reduction,field modeling,and geophysical and geological interpretation of satellite magnetic anomaly data.Howeve...The equivalent source(ES)method in the spherical coordinate system has been widely applied to processing,reduction,field modeling,and geophysical and geological interpretation of satellite magnetic anomaly data.However,the inversion for the ES model suffers from nonuniqueness and instability,which remain unresolved.To mitigate these issues,we introduce both the minimum and flattest models into the model objective function as an alternative regularization approach in the spherical ES method.We first present the methods,then analyze the accuracy of forward calculation and test the proposed ES method in this study by using synthetic data.The experimental results from simulation data indicate that our proposed regularization effectively suppresses the Backus effect and mitigates inversion instability in the low-latitude region.Finally,we apply the proposed method to magnetic anomaly data from China Seismo-Electromagnetic Satellite-1(CSES-1)and Macao Science Satellite-1(MSS-1)magnetic measurements over Africa by constructing an ES model of the large-scale lithospheric magnetic field.Compared with existing global lithospheric magnetic field models,our ES model demonstrates good consistency at high altitudes and predicts more stable fields at low altitudes.Furthermore,we derive the reduction to the pole(RTP)magnetic anomaly fields and the apparent susceptibility contrast distribution based on the ES model.The latter correlates well with the regional tectonic framework in Africa and surroundings.展开更多
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
High-precision time-varying gravity field is an effective way to study the internal mass movement and understanding the spatio-temporal evolution process of the geodynamic system.Compared to the satellite gravity meas...High-precision time-varying gravity field is an effective way to study the internal mass movement and understanding the spatio-temporal evolution process of the geodynamic system.Compared to the satellite gravity measurement,the repeated terrestrial gravity observation can provide a more high-order signal related to the shallow crust and subsurface.However,the suitable and unified method for gravity model estimation is a key problem for further applications.In this study,we introduce the spherical hexahedron element to simulate the field source mass and forward model the change of gravity field located at the Sichuan-Yunnan region(99—104°E,23—29°N)in the four epochs from 2015 to 2017.Compared to the experimental results based on Slepian or spherical harmonics frequency domain method,this alternative approach is suitable for constructing the equivalent mass source model of regional-scale gravity data,by introducing the first-order smooth prior condition of gravity time-varying signal to suppress the high-frequency component of the signal.The results can provide a higher spatial resolution reference for regional gravity field modeling in the Sichuan-Yunnan region.展开更多
Let （K, O, k） be a p-modular system and G be a finite group. We prove that block A of RG and block B of RH are nalurally Morita equivalent of degree n if and only if A≌B＋…＋B}→n^2 as right R[H×H]-modules an...Let （K, O, k） be a p-modular system and G be a finite group. We prove that block A of RG and block B of RH are nalurally Morita equivalent of degree n if and only if A≌B＋…＋B}→n^2 as right R[H×H]-modules and A and B have the same defect（where R∈{k,O}）, which is a generalization of the result of Külshammer Burkhard in a p-modular system for an arbitrary subgroup H of G. It is proved that naturally Morita equivalent blocks are equivalent blocks and Morita equivalent via a bimodule with trivial source.展开更多
The time-domain inverse technique based on the time-domain rotating equivalent source method has been proposed to localize and quantify rotating sound sources. However, this technique encounters two problems to be add...The time-domain inverse technique based on the time-domain rotating equivalent source method has been proposed to localize and quantify rotating sound sources. However, this technique encounters two problems to be addressed: one is the time-consuming process of solving the transcendental equation at each time step, and the other is the difculty of controlling the instability problem due to the time-varying transfer matrix. In view of that, an improved technique is proposed in this paper to resolve these two problems. In the improved technique, a de-Dopplerization method in the time-domain rotating reference frame is frst applied to eliminate the Doppler efect caused by the source rotation in the measured pressure signals, and then the restored pressure signals without the Doppler efect are used as the inputs of the time-domain stationary equivalent source method to locate and quantify sound sources. Compared with the original technique, the improved technique can avoid solving the transcendental equation at each time step, and facilitate the treatment of the instability problem because the transfer matrix does not change with time. Numerical simulation and experimental results show that the improved technique can eliminate the Doppler efect efectively, and then localize and quantify the rotating nonstationary or broadband sources accurately. The results also demonstrate that the improved technique can guarantee a more stable reconstruction and compute more efciently than the original one.展开更多
By using Lagrangian method, the flow properties of a dusty-gas point source in a supersonic free stream were studied and the particle parameters in the near-symmetry-axis region were obtained . It is demonstrated that...By using Lagrangian method, the flow properties of a dusty-gas point source in a supersonic free stream were studied and the particle parameters in the near-symmetry-axis region were obtained . It is demonstrated that fairly inertial particles travel along oscillating and intersecting trajectories between the bow and termination shock waves . In this region, formation of ' mufti- layer structure' in panicle distribution with alternating low- and high density layers is revealed. Moreover, sharp accumulation of particles occurs near the envelopes of particle trajectories .展开更多
In order to overcome the non-unique solution problem of the conventional equivalent source method at the corresponding eigenfrequency,the basic guidelines of adding virtual damping into the equivalent source method is...In order to overcome the non-unique solution problem of the conventional equivalent source method at the corresponding eigenfrequency,the basic guidelines of adding virtual damping into the equivalent source method is proposed according to the damping characteristics of the imaginary part of the coordinates of the equivalent source point.The complex source point constructed by complex retraction is used to add virtual damping to the equivalent source system,and a complex retractive equivalent source method with unique solution in full wavenumber domain is proposed.The mechanism of the complex retraction equivalent source method in overcoming the non-unique solution problem is described in accordance with the zero-point characteristic of the characteristic indicator function,involving the theory,modeling method and selection of damping parameter.The simulation and analysis of typical acoustic radiation and acoustic scattering problems indicate that the present method can obtain the unique solution in the entire frequency domain simply and effectively for arbitrarily shaped acoustic source.Its computational accuracy and efficiency are equivalent to the conventional equivalent source method,which solves the problem of poor adaptability of the complex radius vector method.展开更多
Translation is regarded as a cross-cultural,cross-social,and cross-linguistic communicative activity.In this light,the process of translation is perceived as one of establishing functional equivalence between the sour...Translation is regarded as a cross-cultural,cross-social,and cross-linguistic communicative activity.In this light,the process of translation is perceived as one of establishing functional equivalence between the source text and the target text in order for the latter to be as faithful as possible to the former in both meaning and function.Proverbs are language-and culture-specific expressions,which often cause difficulties in translation.This paper aims to approach proverb translation from the functional equivalence perspective.展开更多
On the basis of the nearfield acoustic holography (NAH) based on the distributed source boundary point method (DSBPM), a novel NAH based on the equivalent source method (ESM) is proposed. The theoretical model of the ...On the basis of the nearfield acoustic holography (NAH) based on the distributed source boundary point method (DSBPM), a novel NAH based on the equivalent source method (ESM) is proposed. The theoretical model of the proposed method is established at first. And then, the error sensitivity and the reconstruction problems of a multi-source acoustic field and a semi-free acoustic field are analyzed, and the corresponding treatment methods are proposed. Subsequently, an experiment on a speaker is investigated to validate the feasibility and correctness of the method. In the method, no discretization is needed on the boundary of the vibrating body. The acoustic field is predicted directly by a set of weighted equivalent sources located inside the vibrating body. Therefore, the variable interpolation, the treatments of singular integrals and non-uniqueness of solutions in the characteristic wave number are avoided. Additionally, the method is adapted to arbitrary-shaped source, so it is really a meshless method. Furthermore, there are such merits as the simple principle, the high calculation efficiency and precision. It is valuabe for the NAH to be applied in the practical engineering field.展开更多
On the basis of nearfield acoustic holography (NAH) based on the equivalent source method (ESM), patch NAH based on the ESM is proposed. The method overcomes the shortcoming in the conventional NAH that the hologram s...On the basis of nearfield acoustic holography (NAH) based on the equivalent source method (ESM), patch NAH based on the ESM is proposed. The method overcomes the shortcoming in the conventional NAH that the hologram surface should be larger than the source surface. It need not to discretize the whole source and its measurement need not to cover the whole source. The measurement may be performed over the region of interest, and the reconstruction can be done in the region directly. The method is flexible in applications, stable in computation, and very easy to implement. It has good potential applications in engineering. The nu- merical simulations show the invalidity of the conventional NAH based on the ESM and prove the validities of the proposed method for reconstructing a partial source and the regularization for reducing the error effect of the pressure measured on the hologram surface.展开更多
Point Sources and Gaussian beams are used frequently as fundamental building blocks for developing ultrasonic beam models. Both these models have different weaknesses that limit their effectiveness. Here, we will show...Point Sources and Gaussian beams are used frequently as fundamental building blocks for developing ultrasonic beam models. Both these models have different weaknesses that limit their effectiveness. Here, we will show that one can develop a Gaussian Beam Equivalent Point Source （GBEPS） model that removes those weaknesses and combines the accuracy and versatility of the point source models with much of the speed and well-behaved nature of Gaussian beam models. We will demonstrate the efficiency and versatility of this new GBEPS model in simulating the beams generated from ultrasonic phased arrays, using as few as one Gaussian beam per element of the array. A single element GBEPS model will be shown to be as accurate as a point source model even when substantial beam focusing or steering is present in the array or where the array beam is transmitted through an interface. At the same time the GBEPS model will be shown to be several orders of magnitude faster than the point source model.展开更多
The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic sources.However,the existing calculation methods suffer from outliers caused by the zero-crossing of the denominat...The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic sources.However,the existing calculation methods suffer from outliers caused by the zero-crossing of the denominator.These outliers can result in inaccuracy and unreliability of harmonic source location.To address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid outliers.The correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring data.The results show that the proposed method is not only simple and easy to implement but also highly accurate.展开更多
The campontely structured inductive waveguide elements are analyzed by making use ofthe equivalent source method in this paper The number and cross section of the inductive posts are arbi-trary, and they are of rither...The campontely structured inductive waveguide elements are analyzed by making use ofthe equivalent source method in this paper The number and cross section of the inductive posts are arbi-trary, and they are of rither pure metallic or pure dielectric lype , or composed of both metallic and di-electric ones. A number of inductive waveguide elements are numerically analyzed and a good agree-ment is achieved in comiparison with the measured data or results available in published literalures.展开更多
An equivalent radiation source method is proposed to characterize electromagnetic emission and interference of complex three dimensional integrated circuits（IC） in this paper.The method utilizes amplitude-only near-...An equivalent radiation source method is proposed to characterize electromagnetic emission and interference of complex three dimensional integrated circuits（IC） in this paper.The method utilizes amplitude-only near-field scanning data to reconstruct an equivalent magnetic dipole array,and the differential evolution optimization algorithm is proposed to extract the locations,orientation and moments of those dipoles.By importing the equivalent dipoles model into a 3D full-wave simulator together with the victim circuit model,the electromagnetic interference issues in mixed RF/digital systems can be well predicted.A commercial IC is used to validate the accuracy and efficiency of this proposed method.The coupled power at the victim antenna port calculated by the equivalent radiation source is compared with the measured data.Good consistency is obtained which confirms the validity and efficiency of the method.展开更多
A physical model of ke V electron scattering in multi-layer medium and a Monte Carlo simulation method proposed by the authors have been successfully applied to theoretical calculation on the emission of backscattered...A physical model of ke V electron scattering in multi-layer medium and a Monte Carlo simulation method proposed by the authors have been successfully applied to theoretical calculation on the emission of backscattered electron, X-ray quantitative analysis in multi-layer films and the energy deposition of electron beam exposure.The model is based on the 'equal number of steps and variational step length' con-cept. In the model, when an electron comes from one medium into another, the scattering number of the electron in the 'new' medium is considered as N-n,展开更多
For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method （ESM） was presented. The normal velocity on the s...For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method （ESM） was presented. The normal velocity on the surface of vibrating structure was first reconstructed by using interior nearfield acoustic holography based on ESM and the prediction of whole interior enclosed sound field was realized. Then the sound pressure produced by each panel at the interested field point was respectively replaced by the radiated pressure of the enclosed interior sound field which is formed by the equivalent virtual sources located near the surface of the cav- ity. Combining with the reconstructed normal surface velocity, the acoustic contribution of each panel to any position in the cavity was obtained by transforming the complex enclosed non-free field into the simple interior free field. Numerical simulations and experiments are conducted, and the influences of the number of the equivalent sources and the distance between them and the reconstructed surface have been investigated. The results show that the proposed method is easier to be implemented with the same accuracy than the traditional analysis method.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.42250103 and 42174090)the Opening Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(Grant No.GLAB2023ZR02)the MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR2022-4).
文摘The equivalent source(ES)method in the spherical coordinate system has been widely applied to processing,reduction,field modeling,and geophysical and geological interpretation of satellite magnetic anomaly data.However,the inversion for the ES model suffers from nonuniqueness and instability,which remain unresolved.To mitigate these issues,we introduce both the minimum and flattest models into the model objective function as an alternative regularization approach in the spherical ES method.We first present the methods,then analyze the accuracy of forward calculation and test the proposed ES method in this study by using synthetic data.The experimental results from simulation data indicate that our proposed regularization effectively suppresses the Backus effect and mitigates inversion instability in the low-latitude region.Finally,we apply the proposed method to magnetic anomaly data from China Seismo-Electromagnetic Satellite-1(CSES-1)and Macao Science Satellite-1(MSS-1)magnetic measurements over Africa by constructing an ES model of the large-scale lithospheric magnetic field.Compared with existing global lithospheric magnetic field models,our ES model demonstrates good consistency at high altitudes and predicts more stable fields at low altitudes.Furthermore,we derive the reduction to the pole(RTP)magnetic anomaly fields and the apparent susceptibility contrast distribution based on the ES model.The latter correlates well with the regional tectonic framework in Africa and surroundings.
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.
基金funded by National Natural Science Foundation of China(U1839207,U1939205)the earthquake tracking directional work task of China Earthquake Administration(No.DZ2022010214)+1 种基金Key project of Spark Program of Seismic Science and Technology of China Earthquake Administration(No.XH20008)S&T Program of Hebei(21375411D)。
文摘High-precision time-varying gravity field is an effective way to study the internal mass movement and understanding the spatio-temporal evolution process of the geodynamic system.Compared to the satellite gravity measurement,the repeated terrestrial gravity observation can provide a more high-order signal related to the shallow crust and subsurface.However,the suitable and unified method for gravity model estimation is a key problem for further applications.In this study,we introduce the spherical hexahedron element to simulate the field source mass and forward model the change of gravity field located at the Sichuan-Yunnan region(99—104°E,23—29°N)in the four epochs from 2015 to 2017.Compared to the experimental results based on Slepian or spherical harmonics frequency domain method,this alternative approach is suitable for constructing the equivalent mass source model of regional-scale gravity data,by introducing the first-order smooth prior condition of gravity time-varying signal to suppress the high-frequency component of the signal.The results can provide a higher spatial resolution reference for regional gravity field modeling in the Sichuan-Yunnan region.
基金Supported by the National Programfor the BasicScience Researches of China(G19990751)
文摘Let （K, O, k） be a p-modular system and G be a finite group. We prove that block A of RG and block B of RH are nalurally Morita equivalent of degree n if and only if A≌B＋…＋B}→n^2 as right R[H×H]-modules and A and B have the same defect（where R∈{k,O}）, which is a generalization of the result of Külshammer Burkhard in a p-modular system for an arbitrary subgroup H of G. It is proved that naturally Morita equivalent blocks are equivalent blocks and Morita equivalent via a bimodule with trivial source.
基金Supported by National Natural Science Foundation of China(Grant Nos.51875147,12174082,51675149)。
文摘The time-domain inverse technique based on the time-domain rotating equivalent source method has been proposed to localize and quantify rotating sound sources. However, this technique encounters two problems to be addressed: one is the time-consuming process of solving the transcendental equation at each time step, and the other is the difculty of controlling the instability problem due to the time-varying transfer matrix. In view of that, an improved technique is proposed in this paper to resolve these two problems. In the improved technique, a de-Dopplerization method in the time-domain rotating reference frame is frst applied to eliminate the Doppler efect caused by the source rotation in the measured pressure signals, and then the restored pressure signals without the Doppler efect are used as the inputs of the time-domain stationary equivalent source method to locate and quantify sound sources. Compared with the original technique, the improved technique can avoid solving the transcendental equation at each time step, and facilitate the treatment of the instability problem because the transfer matrix does not change with time. Numerical simulation and experimental results show that the improved technique can eliminate the Doppler efect efectively, and then localize and quantify the rotating nonstationary or broadband sources accurately. The results also demonstrate that the improved technique can guarantee a more stable reconstruction and compute more efciently than the original one.
基金Foundation items : the National Natural Science Foundation of China ( NSFC grant No.90205024) the Russian Foundation for Basic Research (RFBR grant No. 02-01-00770) RFBR-NSFC grant No.99-01-39020)
文摘By using Lagrangian method, the flow properties of a dusty-gas point source in a supersonic free stream were studied and the particle parameters in the near-symmetry-axis region were obtained . It is demonstrated that fairly inertial particles travel along oscillating and intersecting trajectories between the bow and termination shock waves . In this region, formation of ' mufti- layer structure' in panicle distribution with alternating low- and high density layers is revealed. Moreover, sharp accumulation of particles occurs near the envelopes of particle trajectories .
基金supported by the National Natural Science Foundation of China(12364055,51775121).
文摘In order to overcome the non-unique solution problem of the conventional equivalent source method at the corresponding eigenfrequency,the basic guidelines of adding virtual damping into the equivalent source method is proposed according to the damping characteristics of the imaginary part of the coordinates of the equivalent source point.The complex source point constructed by complex retraction is used to add virtual damping to the equivalent source system,and a complex retractive equivalent source method with unique solution in full wavenumber domain is proposed.The mechanism of the complex retraction equivalent source method in overcoming the non-unique solution problem is described in accordance with the zero-point characteristic of the characteristic indicator function,involving the theory,modeling method and selection of damping parameter.The simulation and analysis of typical acoustic radiation and acoustic scattering problems indicate that the present method can obtain the unique solution in the entire frequency domain simply and effectively for arbitrarily shaped acoustic source.Its computational accuracy and efficiency are equivalent to the conventional equivalent source method,which solves the problem of poor adaptability of the complex radius vector method.
文摘Translation is regarded as a cross-cultural,cross-social,and cross-linguistic communicative activity.In this light,the process of translation is perceived as one of establishing functional equivalence between the source text and the target text in order for the latter to be as faithful as possible to the former in both meaning and function.Proverbs are language-and culture-specific expressions,which often cause difficulties in translation.This paper aims to approach proverb translation from the functional equivalence perspective.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50275044)the Research Fund for theDoctoral Program of Higher Education(Grant No.20020359005).
文摘On the basis of the nearfield acoustic holography (NAH) based on the distributed source boundary point method (DSBPM), a novel NAH based on the equivalent source method (ESM) is proposed. The theoretical model of the proposed method is established at first. And then, the error sensitivity and the reconstruction problems of a multi-source acoustic field and a semi-free acoustic field are analyzed, and the corresponding treatment methods are proposed. Subsequently, an experiment on a speaker is investigated to validate the feasibility and correctness of the method. In the method, no discretization is needed on the boundary of the vibrating body. The acoustic field is predicted directly by a set of weighted equivalent sources located inside the vibrating body. Therefore, the variable interpolation, the treatments of singular integrals and non-uniqueness of solutions in the characteristic wave number are avoided. Additionally, the method is adapted to arbitrary-shaped source, so it is really a meshless method. Furthermore, there are such merits as the simple principle, the high calculation efficiency and precision. It is valuabe for the NAH to be applied in the practical engineering field.
基金the National Natural Science Foundation of China (Grant Nos. 10504006 and 50675056) the Research Fund for the Doctoral Program of Higher Education (Grant No. 20060359003)
文摘On the basis of nearfield acoustic holography (NAH) based on the equivalent source method (ESM), patch NAH based on the ESM is proposed. The method overcomes the shortcoming in the conventional NAH that the hologram surface should be larger than the source surface. It need not to discretize the whole source and its measurement need not to cover the whole source. The measurement may be performed over the region of interest, and the reconstruction can be done in the region directly. The method is flexible in applications, stable in computation, and very easy to implement. It has good potential applications in engineering. The nu- merical simulations show the invalidity of the conventional NAH based on the ESM and prove the validities of the proposed method for reconstructing a partial source and the regularization for reducing the error effect of the pressure measured on the hologram surface.
基金supported by the National Science Foundation Industry/University Cooperative Research Center program at Iowa State Universitythe Natural Sciences and Engineering Research Council of Canadaby the National Natural Science Foundation of China(NSFC)
文摘Point Sources and Gaussian beams are used frequently as fundamental building blocks for developing ultrasonic beam models. Both these models have different weaknesses that limit their effectiveness. Here, we will show that one can develop a Gaussian Beam Equivalent Point Source （GBEPS） model that removes those weaknesses and combines the accuracy and versatility of the point source models with much of the speed and well-behaved nature of Gaussian beam models. We will demonstrate the efficiency and versatility of this new GBEPS model in simulating the beams generated from ultrasonic phased arrays, using as few as one Gaussian beam per element of the array. A single element GBEPS model will be shown to be as accurate as a point source model even when substantial beam focusing or steering is present in the array or where the array beam is transmitted through an interface. At the same time the GBEPS model will be shown to be several orders of magnitude faster than the point source model.
基金supported by the National Natural Science Foundation of China(No.51777035).
文摘The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic sources.However,the existing calculation methods suffer from outliers caused by the zero-crossing of the denominator.These outliers can result in inaccuracy and unreliability of harmonic source location.To address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid outliers.The correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring data.The results show that the proposed method is not only simple and easy to implement but also highly accurate.
文摘The campontely structured inductive waveguide elements are analyzed by making use ofthe equivalent source method in this paper The number and cross section of the inductive posts are arbi-trary, and they are of rither pure metallic or pure dielectric lype , or composed of both metallic and di-electric ones. A number of inductive waveguide elements are numerically analyzed and a good agree-ment is achieved in comiparison with the measured data or results available in published literalures.
基金supported by the National Nature Science Foundation of China(No.61274110)
文摘An equivalent radiation source method is proposed to characterize electromagnetic emission and interference of complex three dimensional integrated circuits（IC） in this paper.The method utilizes amplitude-only near-field scanning data to reconstruct an equivalent magnetic dipole array,and the differential evolution optimization algorithm is proposed to extract the locations,orientation and moments of those dipoles.By importing the equivalent dipoles model into a 3D full-wave simulator together with the victim circuit model,the electromagnetic interference issues in mixed RF/digital systems can be well predicted.A commercial IC is used to validate the accuracy and efficiency of this proposed method.The coupled power at the victim antenna port calculated by the equivalent radiation source is compared with the measured data.Good consistency is obtained which confirms the validity and efficiency of the method.
基金Project supported by the National Natural Science Foundation of China
文摘A physical model of ke V electron scattering in multi-layer medium and a Monte Carlo simulation method proposed by the authors have been successfully applied to theoretical calculation on the emission of backscattered electron, X-ray quantitative analysis in multi-layer films and the energy deposition of electron beam exposure.The model is based on the 'equal number of steps and variational step length' con-cept. In the model, when an electron comes from one medium into another, the scattering number of the electron in the 'new' medium is considered as N-n,
基金supported by the National Natural Science Foundation of China(11274087)
文摘For the interior sound field formed by the complex vibrating structure, an identifi- cation approach of panel acoustic contribution based on equivalent source method （ESM） was presented. The normal velocity on the surface of vibrating structure was first reconstructed by using interior nearfield acoustic holography based on ESM and the prediction of whole interior enclosed sound field was realized. Then the sound pressure produced by each panel at the interested field point was respectively replaced by the radiated pressure of the enclosed interior sound field which is formed by the equivalent virtual sources located near the surface of the cav- ity. Combining with the reconstructed normal surface velocity, the acoustic contribution of each panel to any position in the cavity was obtained by transforming the complex enclosed non-free field into the simple interior free field. Numerical simulations and experiments are conducted, and the influences of the number of the equivalent sources and the distance between them and the reconstructed surface have been investigated. The results show that the proposed method is easier to be implemented with the same accuracy than the traditional analysis method.
