Equivalent Currents on an Anisotropic Material Backed by a Metal Surface and Their Relation

Based on a first-order state-vector differential equation representation of Maxwell's equations, an analytical formulation is derived for the equivalent currents on an anisotropic material backed by a metal surface, and the relation between two currents is also considered. These expressions are degenerated into the common forms for some simple cases. This effort will provide the theoretical preparation for the approximate calculation of electromagnetic scattering from a conducting object coated by an anisotropic material.

Application of the method of equivalent edge currents to composite scattering from the cone-cylinder above a dielectric rough sea surface

Compared with scattering from a rough surface only, composite scattering from a target above a rough surface has become so practical that it is a subject of great interest. At present, this problem has been solved by some numerical methods which will produce an enormous calculation amount. In order to overcome this shortcoming, the reciprocity theorem （RT） and the method of equivalent edge currents （MEC） are used in this paper. Due to the advantage of RT, the difficulty in computing the secondary scattered fields is reduced. Simultaneously, MEC, a high-frequency method with edge diffraction considered, is used to calculate the scattered field from the cone-cylinder target with a high accuracy and efficiency. The backscattered field and the polarization currents of the rough sea surface are evaluated by the Kirchhoff approximation （KA） method and physical optics （PO） method, respectively. The effects of the backscattering radar cross section （RCS） and the Doppler spectrum on the size of the target and the windspeed of the sea surface for different incident angles are analysed in detail.

Application of improved equivalent edge currents in synthetic aperture radar imaging

Target modeling and scattering function calculating are important prerequisites and groundwork for the synthetic aperture radar（SAR） imaging simulation.According to the difficult problems that normal methods cannot calculate the scattering function of electrically large object under the condition to wideband,an effective method of improved equivalent edge currents is presented and applied to SAR imaging simulation for the first time.This method improves calculating velocity and has relatively high precision.The concrete steps of applying the method are given.By way of the simulation experiment,the effectiveness of the method is verified.

Relationship Between Noise Figure and Equivalent Input Noise Current Spectral Density for Optical Receiver Design

Based on the equivalent circuit model of a two-port optical receiver front-end,the relationship between the equivalent input noise current spectral density and the noise figure is analyzed. The derived relationship has universal validity for determining the equivalent input noise current spectral density for optical receiver designs, as verified by measuring a 155Mb/s high-impedance optical receiver front.end. Good agreement between calculated and simulated results has been achieved.

Analysis of each branch current of serial solar cells by using an equivalent circuit model

In this paper, based on the equivalent single diode circuit model of the solar cell, an equivalent circuit diagram for two serial solar cells is drawn. Its equations of current and voltage are derived from Kirchhoff＇s current and voltage law. First, parameters are obtained from the I-V （current-voltage） curves for typical monocrystalline silicon solar cells （125 mmx 125 mm）. Then, by regarding photo-generated current, shunt resistance, serial resistance of the first solar cell, and resistance load as the variables. The properties of shunt currents （Ishl and Ish2）, diode currents （/D1 and/]：）2）, and load current （IL） for the whole two serial solar cells are numerically analyzed in these four cases for the first time, and the corresponding physical explanations are made. We find that these parameters have different influences on the internal currents of solar cells. Our results will provide a reference for developing higher efficiency solar cell module and contribute to the better understanding of the reason of efficiency loss of solar cell module.

Validity and Accuracy of Eddy Current Field Analysis of Laminations by Introducing Equivalent Conductivities

对于分析叠片铁心中的涡流问题，利用各种等效电导率替代硅钢片实际电导率的匀质化方法是很有应用前景的。为了评估各种电导率模型，该文提出了铁心涡流场分析的二维解析验证方法，并分别基于引入各向异性或各向同性等效电导率的铁心连续体表述和实际叠片表述对涡流场进行了解析计算。通过比较连续体表述下所得到的平均磁通密度和涡流损耗值与相应由实际叠片表述所得到的精确解，对各种电导率模型的有效性和准确性在各种条件下进行了评估。为了进一步考察电导率模型对实际工程问题的适用性，利用有限元法进行了关于TEAM21面向工程基准问题的磁通和杂散场损耗计算。计算结果表明，由该文作者所提出的等效电导率模型优于其他模型。

Electric Potential in a Dielectric Sphere Head Produced by a Time-Harmonic Equivalent Current Dipole

A time-harmonic equivalent current dipole model is proposed to simulate EEG source which deals with the problem concerning the capacitance effect. The expressions of potentials in both homogeneous infinite dielectric medium and dielectric sphere on the electroquasistatic condition are presented. The potential in a 3-layer inhomogeneous spherical head is computed by using this model. The influences on potential produced by time-harmonic character and permittivity are discussed. The results show that potentials in dielectric sphere are affected by frequency and permittivity.

Prediction of Reinforcement Corrosion based on Electrochemical Equivalent under Loading

Experiment was carried out to simulate different loading level elements under coupling of stray current and 5% chlorine salt solution. When calculating corrosion of reinforcement, the influence of loading should be considered based on the first law of Faraday electrolysis. The current density of the corrosion was measured by the linear polarization resistance method. The function of corrosion current density was obtained by nonlinear fitting method, and the influence coefficient of loading level to electrochemical equivalent was obtained base on the function of corrosion current density. The experimental results show that the corrosion current density increases with stress ratio of concrete structures. The reinforcement corrosion weight can be calculated through the influence coefficients of electrochemical equivalent and the result is in line with the actual situation.

Research on the Equivalence Between Double Differential- mode Current Injection and Radiation Test Method

There are the application scope limits for single differential-mode current injection test method, so in order to carry out injection susceptibility test for two-pieces equipment interconnected with both ends of a cable simultaneously, a double differential-mode current in- jection test method (DDMCI) is proposed. The method adopted the equivalence source wave theorem and Baum-Liu-Tesche(BLT) equation as its theory foundation. The equivalent corresponding relation between injection voltage and radiation electric field intensity is derived, and the phase relation between the two injection voltage sources is confirmed. The results indicate that the amplitude and phase of the equivalent injection voltage source is closely related to the S parameter of directional coupling device, the transmission line length, and the source vector in BLT equation, but has nothing to do with the reflection coefficient between the two equipment pieces. Therefore, by choosing the right amplitude and phase of the double injection voltage sources, the DDMCI test is equivalent to the radiation test for two interconnected equipment of a system.

Equivalent magnetic dipole method used to design gradient coil for unilateral magnetic resonance imaging

The conventional magnetic resonance imaging(MRI)equipment cannot measure large volume samples nondestructively in the engineering site for its heavy weight and closed structure.In order to realize the mobile MRI,this study focuses on the design of gradient coil of unilateral magnet.The unilateral MRI system is used to image the local area above the magnet.The current density distribution of the gradient coil cannot be used as a series of superconducting nuclear magnetic resonance gradient coils,because the region of interest(ROI)and the wiring area of the unilateral magnet are both cylindrical side arc surfaces.Therefore,the equivalent magnetic dipole method is used to design the gradient coil,and the algorithm is improved for the special case of the wiring area and the ROI,so the X and Y gradient coils are designed.Finally,a flexible printed circuit board(PCB)is used to fabricate the gradient coil,and the magnetic field distribution of the ROI is measured by a Gauss meter,and the measured results match with the simulation results.The gradient linearities of x and y coils are 2.82%and 3.56%,respectively,less than 5%of the commercial gradient coil requirement.

A General Study on Equivalent Resistance of Three-Terminal Ladder Network

In view of the application importance of resistance network in modern science and technology, this paper presents the basic structure of a three terminals ladder shaped resistance network, for which, to study in- depth the equivalent resistance, carry out network analysis by applying virtual current method and construct a model of two elements three orders differential equation. Based on different marginal conditions, two general adaptive rules for the three-terminal ladder shaped inlet resistance, as well as two ultimate rules for the equiva- lent resistance of three-terminal infinite ladder shaped were given.

MoM-PO-MEC混合法及其在组合体散射中的应用

对于携带电小结构的电大目标的散射问题,单纯的矩量法(MoM)或单纯的物理光学法(PO)由于自身固有的缺点,都不能给出有效的结果.而矩量法与物理光学法的混合方法是解决此类问题的有效途径,本文在MoM-PO混合法的基础上,通过引入等效电磁流方法(MEC)来计算PO区域边缘的绕射贡献,提出了一种MoM-PO-MEC混合方法,并将其计算结果与多层快速多极子计算结果进行比较,最终证明了该混合方法的有效性。

基于等效磁路的PMECD变种群规模遗传多目标优化设计

基于等效磁路模型,提出了一种使用引入死亡和战争因素的变种群规模遗传算法进行永磁涡流驱动器的多目标优化设计的方法.首先建立磁场分析模型,推导关键参数的解析表达式.在此基础上,以永磁体厚度、极弧系数、铜盘厚度以及永磁体个数为变量,以输出转矩、转动惯量和驱动器体积为优化目标,提出了基于熵值权重的永磁驱动器多目标优化函数,然后应用引入死亡和战争因素的变种群规模遗传算法来优化结构尺寸.优化结果得到了实验以及有限元仿真的验证,并且与其他算法进行了比较.结果表明,相比其他优化算法,该基于解析模型的变种群规模遗传算法在结构参数优化设计中有很好的计算效果.

THEORETICAL INVESTIGATION ON BY-ONLY-CURRENT ELECTROMAGNETIC SEPARATION OF INCLUSION FROM MOLTEN METALS

The electromagnetic field under applied AC and DC current in round and rectangular pipe was systematically investigated, then a concept of 'equivalent current density' was proposed for evaluating the inhomogeneous electromagnetic pinch force, and the mono-component removal efficiency and the overall removal efficiency of inclusion were formulated. It is founded that flat pipe is superior to round pipe for the electromagnetic removal of inclusion, and DC current can get a higher removal efficiency than A C current due to absence of skin phenomenon. Under usual condition, a removal efficiency of 52% for 10μm inclusion or more than 92% for 20μm inclusion can be achieved by imposing a current density of 3×106A/m2 in a flat pipe.

Vacuum Dielectric Recovery Characteristics of a Novel Current Limiting Circuit Breaker Base on Artificial Current Zero

为了保证新型强迫换流型真空直流限流断路器关断短路电流的可靠性，对该型断路器分断过程的真空介质恢复特性进行研究。设计了与断路器关断过程等效的介质恢复试验方案，通过等效试验结果和理论推演公式的拟合，得到了新型强迫换流型限流断路器真空灭弧室触头打开过程的动态介质强度恢复规律。研究结果表明：减小燃弧能量、提高触头运动速度可提高真空灭弧室介质的临界击穿电压；综合考虑燃弧时间与燃弧能量及触头开距的关系，随着燃弧时间的增加，真空灭弧室临界击穿电压先减小后增大。所得介质恢复规律可以作为新型断路器优化设计的参考依据。

ESTABLISHMENT AND VERIFICATION OF MATHEMATICAL MODEL FOR CURRENT LEAKAGE IN BIPOLAR MULTI－COMPARTMENT CELL

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The Principle of Calibration Using the Ionic Current——A New Calibration Method for Electro-Magnetic Flowmeters

An equivalent relationship between electro magnetic flowmeters (EMFs) and the Hall effect is discussed in principle and three equivalent conclusions about their measuring equations are derived. Thereby,the calibration using the ionic current (CUIC) is introduced to the calibration of EMFs in a special Hall effect system. A basic system with these equations is specially given and discussed for realizing the method. Two key points about CUIC are proved by a simple experiment.

A study on the multi-componentsubstrom current

A new technique of eigen mode analysis, Method of Natural Orthogonal Components (MNOC) is used to analyze the ionospheric equivalent current systems obtained on the basis of magnetic data at six meridian magnetometer chains in the northern hemisphere during March 17 19, 1978. The results show that the whole current pattern for any given instant consists of a few eigen modes with different intensities. The first eigen mode exhibits a two cell current construction, characterizing the large scale magnetospheric convection and directly driven process, while the second eigen mode shows a concentrated westward electrojet at midnight sector, characterizing the substorm current wedge and the loading unloading process. The first mode consistently exists whenever during quiet periods or at substorms, and its intensity increases from the beginning of the growth phase of substorms, then quickly intensifies in the expansion phase, followed by a gradual decrease in the recovery phase. On the other hand, the intensity of the second mode remains to be near zero during both quiet time and the growth phase of substorms. Its rapid enhancement occurs in the expansion phase. These characteristics in the current patterns and the intensity variations coincide with the defined physical processes of the directly driven and loading unloading components.