Three-dimensional Electromagnetic Model Research Articles

Optimal Scheme for Structural Design of Large Turbogenerator Stator End Winding

A three-dimensional (3-D) electromagnetic model of the end region of a 600 MW turbogenerator is set up. The variations of electromagnetic force densities of the stator end winding under rated load and three-phase short circuit from full load are obtained by numerical simulation. Then, the electromagnetic forces varying with time and space on the end winding are applied to the 3-D fine finite-element model established in ABAQUS/CAE for structural analysis, and the deformation and stress distributions of the stator end winding during rated load and three-phase short circuit are numerically analyzed by means of the ABAQUS software. Furthermore, the influences of structural and material parameters of the end winding on its dynamic responses under rated load are numerically investigated. Based on the numerical results, an optimal scheme for the design of the turbogenerator stator end winding is proposed.

Three-dimensional electromagnetic model–based scattering center matching method for synthetic aperture radar automatic target recognition by combining spatial and attributed information

A three-dimensional electromagnetic model (3-D EM-model)–based scattering center matching method is developed for synthetic aperture radar automatic target recognition (ATR). 3-D EM-model provides a concise and physically relevant description of the target’s electromagnetic scattering phenomenon through its scattering centers which makes it an ideal candidate for ATR. In our method, scatters of the 3-D EM-model are projected to the two-dimensional measurement plane to predict scatters’ location and scattering intensity properties. Then the identical information is extracted for scatters in measured data. A two-stage iterative operation is applied to match the model-predicted scatters and the measured data-extracted scatters by combining spatial and attributed information. Based on the two scatter sets’ matching information, a similarity measurement between model and measured data is obtained and recognition conclusion is made. Meanwhile, the target’s configuration is reasoned with 3-D EM-model serving as a reference. In the end, data simulated by electromagnetic computation verified this method’s validity.

Advantages and Challenges of 10-Gbps Transmission on High-Density Interconnect Boards

This paper provides a brief introduction to high-density interconnect (HDI) technology and its implementation on printed circuit boards (PCBs). The advantages and challenges of implementing 10-Gbps signal transmission on high-density interconnect boards are discussed in detail. The advantages (e.g., smaller via dimension and via stub removal) and challenges (e.g., crosstalk due to smaller interpair separation) of HDI are studied by analyzing the S-parameter, time-domain reflectometry (TDR), and transmission-line eye diagrams obtained by three-dimensional electromagnetic modeling (3DEM) and two-dimensional electromagnetic modeling (2DEM) using Mentor Graphics HyperLynx and Keysight Advanced Design System (ADS) electronic computer-aided design (ECAD) software. HDI outperforms conventional PCB technology in terms of signal integrity, but proper routing topology should be applied to overcome the challenge posed by crosstalk due to the tight spacing between traces.

Accurate, full-chip, three-dimensional electromagnetic field model for non-Manhattan mask corners

The physical process of mask manufacturing produces absorber geometry with significant deviations from the 90-deg corners, which are typically assumed in the mask design. The non-Manhattan mask geometry is an essential contributor to the aerial image and resulting patterning performance through focus. Current state-of-the-art models for corner rounding employ “chopping” a 90-deg mask corner, replacing the corner with a small 45-deg edge. A methodology is presented to approximate the impact of three-dimensional (3-D) EMF effects introduced by corners with rounded edges. The approach is integrated into a full-chip 3-D mask simulation methodology based on the domain decomposition method with edge to edge crosstalk correction.

Compact Dual-Band Bandpass Waveguide Filter with H-Plane Inserts

A novel compact dual-band bandpass waveguide filter is presented in this paper. H-plane metal inserts with complementary split-ring resonators are implemented as resonating elements in the standard (WR-90) rectangular waveguide. Design starts from the models of the waveguide resonators with two resonant frequencies (9[Formula: see text]GHz and 11[Formula: see text]GHz) using a single flat or folded metal insert. Further, folded inserts are used for the second-order dual-band filter design. The equivalent circuits are proposed for the considered waveguide resonators and filter. A good agreement of the amplitude responses obtained for three-dimensional electromagnetic models and microwave circuits is achieved. Finally, compact dual-band bandpass waveguide filter is proposed as a novel solution using miniaturized inverters for both central frequencies. Compact filter model is further modified in order to obtain solution customized for easier fabrication. For the compact filter model, amplitude response is experimentally verified. The required filter response is preserved, as verified by a good agreement of the results obtained for the original dual-band filter and for the compact filter solutions.

Internal model control of inductive magnetic suspension spherical active joints based on fuzzy neural network inverse system

This article puts forward inductive magnetic suspension spherical active joints and has researched on its mechanism. The expression of motor’s electromagnetic torque is derived from the point of power balance of three-dimensional electromagnetic model, and on the basis of the air gap magnetic flux density distribution, we establish the joint’s mathematical model of electromagnetic levitation force. The relationship between the two of displacement, angle, and current and the transfer function expression of motor system are derived by the state equation and the inverse system theory We established the inverse system of joint’s original system using fuzzy neural network theory and simplified coupling relationship of the motor’s complex multivariable to establish ANFIS model of joint’s inverse system. An internal model controller with high robustness and stability was designed, and an internal model control joint pseudo linear system was built. According to the simulation analysis and experimental verification of the joint control system, the conclusion indicates that the rotor has quick dynamic response and high robustness.

Three-dimensional tensor controlled-source electromagnetic modeling based on the vector finite-element method

Scalar CSAMT is only suitable for measurements in one and two dimensions perpendicular to geological structures. For complex 3D geoelectric structure, tensor CSAMT is more suitable. In this paper, we discuss 3D tensor CSAMT forward modeling using the vector finite-element method. To verify the feasibility of the algorithm, we calculate the electric field, magnetic field, and tensor impedance of the 3D CSAMT far-zone field in layered media and compare them with theoretical solutions. In addition, a three-dimensional anomaly in half-space is also simulated, and the response characteristics of the impedance tensor and the apparent resistivity and impedance phase are analyzed. The results suggest that the vector finite-element method produces high-precision electromagnetic field and impedance tensor data, satisfies the electric field discontinuity, and does not require divergence correction using the vector finite-element method.

Three-dimensional electromagnetic responses of disk-shaped hydrocarbon reservoir in marine sediments

This paper presents a three-dimensional (3D) marine controlled-source electromagnetic modeling algorithm using primary fields for a homogeneous half-space to accurately account for airwave effects. This algorithm is validated with analytic solutions for 1D two- and four-layer models and numerical results from another 3D model. Using this code, we investigate the 3D electromagnetic responses of a 100 m thick, 5 km disk-shaped hydrocarbon reservoir buried at a depth of 1 km below the seafloor. From the numerical results, we can recognize that a 3D effect of the reservoir typically produces a transition zone in comparison with 1D model responses. The transition zone decreases with the airwave effect as the depth of water becomes shallow. As the source frequency increases, the sensitivity to the reservoir increases, whereas the amplitude decreases and falls at higher than 1 Hz below the current system noise floor. Broadside electric fields for a 10-km diameter disk model are only about 5% of in-line electric fields for the 5-km disk model. The Tequivalence is observed at such a low frequency of 1 Hz for the thin resistive tabular target, whose response varies almost linearly with the target thickness and resistivity even in the transition zone.

Electromagnetic modeling and resonant detectors and arrays

We recently developed a finite element three-dimensional electromagnetic model for quantum efficiency (QE) computation. It is applicable to any arbitrary detector geometry and materials. Using this model, we can accurately account for the open literature experimental results that we have investigated, which include those from GaAs solar cells, GaSb type-II superlattices, and GaAs quantum wells. We applied the model to design a photon trap to increase detector QE. By accumulating and storing incident light in the resonator-QWIP structure, we observed experimental QE as high as 71%. This improvement shows that we are now able to fully determine the optical properties of QWIPs. For example, we can design QWIPs to detect at certain wavelengths with certain bandwidths. To illustrate this capability, we designed QWIPs with its QE spectrum matching well with the transmission spectrum of a medium. We subsequently produced several focal plane arrays according to these designs with 640×512 and 1K×1K formats. In this paper, we will compare the modeled QE and the experimental results obtained from single detectors as well as FPAs.

주파수영역 전자법의 3차원 모델링

주파수영역 전자법의 3차원 모델링

Algebraic multigrid preconditioning within parallel finite-element solvers for 3-D electromagnetic modelling problems in geophysics

We present an elaborate preconditioning scheme for Krylov subspace methods which has been developed to improve the performance and reduce the execution time of parallel node-based finite-element solvers for three-dimensional electromagnetic numerical modelling in exploration geophysics. This new preconditioner is based on algebraic multigrid that uses different basic relaxation methods, such as Jacobi, symmetric successive over-relaxation and Gauss-Seidel, as smoothers and the wave-front algorithm to create groups, which are used for a coarse-level generation. We have implemented and tested this new preconditioner within our parallel nodal finite-element solver for three-dimensional forward problems in electromagnetic induction geophysics. We have performed series of experiments for several models with different conductivity structures and characteristics to test the performance of our algebraic multigrid preconditioning technique when combined with biconjugate gradient stabilised method. The results have shown that, the more challenging the problem is in terms of conductivity contrasts, ratio between the sizes of grid elements and/or frequency, the more benefit is obtained by using this preconditioner. Compared to other preconditioning schemes, such as diagonal, symmetric successive over-relaxation and truncated approximate inverse, the algebraic multigrid preconditioner greatly improves the convergence of the iterative solver for all tested models. Also, when it comes to cases in which other preconditioners succeed to converge to a desired precision, algebraic multigrid is able to considerably reduce the total execution time of the forward-problem code -up to an order of magnitude. Furthermore, the tests have confirmed that our algebraic multigrid scheme ensures grid-independent rate of convergence, as well as improvement in convergence regardless of how big local mesh refinements are. In addition, algebraic multigrid is designed to be a black-box preconditioner, which makes it easy to use and combine with different iterative methods. Finally, it has proved to be very practical and eficient in the parallel context.

적분방정식 기반의 3차원 모델링을 이용한 소형 루프형 해양 전자탐사 자료의 반응 분석

심해탐사를 위해 새롭게 개발된 소형 루프형 해양 전자탐사 시스템의 실해역 실험 결과의 반응 양상을 적분방정식 기반의 3차원 모델링을 통하여 분석하였다. 수심 약 300 m 해저환경에서 획득한 금속 이상체의 전자기 반응 양상에 대한 영향인자를 분석하기 위해 이상체의 크기와 모양을 다르게 설정하여 모델링을 수행하였다. 모델링 결과 분석을 통하여 이상체의 모양이 크기보다 반응 양상에 더 큰 영향을 주는 것을 확인하였다. 탐사고도와 주파수에 따른 반응값 변화를 알아보기 위해 모델링을 수행하였고 이를 통해 일정한 탐사 고도 유지의 필요성과 주파수 대역에 따른 허수부의 민감도를 확인하였다. 또한 탐사 고도와 주파수에 따른 반응값을 단면 그래프로 나타내어 시스템에 사용되는 주파수 대역에 대한 적절한 탐사고도를 제시하였다. 본 연구를 통해 도출된 결과는 해저 열수광상 실해역 탐사 설계 시 매개변수 설정에 있어 유용한 정보를 줄 것으로 예상된다. We analyzed response patterns of test field data acquired with new small loop electromagnetic (EM) system using three-dimensional (3D) electromagnetic modeling code. The size and shape of a conductor was adopted as experimental parameters for EM modeling to understand influencing factors of the response patterns due to a metallic object on the seafloor. Obtaining the responses for four models of difference sizes and shapes through 3D EM modeling, we confirmed that the shape of the object have a more critical factor on the response pattern than size. We also calculated "ppm" values with respect to different altitudes of the sensor and source frequencies. The modeling results show that the consistency of sensor altitude is important and imaginary part of ppm response is more sensitive than real part. We also visualized the contour map of the real and imaginary part of ppm value as a function of frequency and altitude so that we can estimate proper altitude for source frequency band of our survey system. The results of this paper are anticipated to give proper parameters in survey construction for seafloor massive sulfide deposit.

Combined three-dimensional electromagnetic and device modeling of surface plasmon-enhanced organic solar cells incorporating low aspect ratio silver nanoprisms

We investigate silver nanoparticle enhanced organic solar cells by coupling three-dimensional electromagnetic and electronic device simulations. For active layer thicknesses of less than 50 nm, an array of optimized silver nanoprisms with 10 nm edge length, 15 nm thickness, and 17 nm period length can enhance the power conversion efficiency (PCE) by more than 25% when embedded in a bulk heterojunction polymer blend. For thicker layers, optical losses associated with the particles outweigh the increased absorption and reduce the PCE. Additionally, we find that the nanoparticle's work function determines the current-voltage behavior of plasmonic devices.

A parallel finite-element method for three-dimensional controlled-source electromagnetic forward modelling

SUMMARY We present a nodal finite-element method that can be used to compute in parallel highly accurate solutions for 3-D controlled-source electromagnetic forward-modelling problems in anisotropic media. Secondary coupled-potential formulation of Maxwell’s equations allows to avoid the singularities introduced by the sources, while completely unstructured tetrahedral meshes and mesh refinement support an accurate representation of geological and bathymetric complexity and improve the solution accuracy. Different complex iterative solvers and an efficient pre-conditioner based on the sparse approximate inverse are used for solving the resulting large sparse linear system of equations. Results are compared with the ones of other researchers to check the accuracy of the method. We demonstrate the performance of the code in large problems with tens and even hundreds of millions of degrees of freedom. Scalability tests on massively parallel computers show that our code is highly scalable.

유한차분법에 기초한 인공송신원 해양전자탐사 모델링

이 연구에서는 다양한 환경에서 인공송신원 해양전자탐사 자료의 정확한 해석을 위해 3차원 모델링 알고리듬을 개발하고, 복잡한 탄화수소자원 개발 환경에서 인공송신원 해양전자탐사의 적용 가능성을 파악하고자 암염에 인접한 저류층 모형을 구성하고 그 반응을 계산 및 분석하였다. 모델링 알고리듬은 유한차분법에 기초하고 있으며 이차 전기장 정식화를 도입함으로써 빠르고 정확한 반응 계산이 가능하도록 하였다. 이 알고리듬의 정확성은 2층구조 모형에 대해 해석해 및 기존의 3차원 모델링 알고리듬의 결과와의 비교를 통해 검증되었다. 암염에 인접한 저류층 모형에서는 암염과 저류층 및 배경 매질의 경계에 존재하는 세 군데 송신원에 대한 전기장 및 자기장 반응을 파악하고, 배경매질의 반응으로 정규화한 전기장 및 자기장 반응도 분석하였다. 그 결과 세 군데 송신원에 대한 반응을 종합하면 정규화된 전자기장 반응으로부터 지하의 고비저항 이상체의 개수와 각각의 위치를 파악할 수 있었으며 탄성파탐사를 통해 암염의 구조가 사전 정보로 알려졌다면 저류층의 존재를 밝힐 수 있었다. 이 연구에서 개발한 알고리듬은 향후 다양한 환경에서 인공송신원 해양전자탐사 자료의 반응 분석은 물론 역산 알고리듬 개발에 유용할 것으로 기대된다. This paper presents development of a three-dimensional marine controlled-source electromagnetic (mCSEM) modeling algorithm and its application to a salt and reservoir model to examine detectability of mCSEM for a reservoir under complex subsurface structures. The algorithm is based on the finite difference method, and employs the secondary field formulation for an accurate and fast calculation of modeling responses. The algorithm is verified for a two-layer model by comparing solutions not only with analytic solutions but also with those from other 3D modeling algorithm. We calculate and analyze electric and magnetic fields and their normalized responses for a salt and reservoir model due to three sources located at boundaries between a salt, a reservoir, and background. Numbers and positions of resistive anomalies are informed by normalized responses for three sources, and types of resistive anomalies can be informed when there is a priori information about a salt by seismic exploration.

Studying the Impact of Return Current Path on the EM Simulation of High-Speed Package and Board Designs

Three-dimensional electromagnetic simulation models are often simplified in order to reduce simulation time and memory requirements without sacrificing the accuracy of the results. A commonly adopted methodology in the simulation of complex electronic package and board designs is to truncate the size of the model, leaving only a few important features surrounding the nets of interest. In this paper we demonstrate that this simplification can have a significant impact on the simulation results if it is not performed carefully, and it can introduce spurious nonphysical resonances. The interaction between cavities and signals is first studied using a simple coupled differential via test structure. It is demonstrated that the return currents generated by these vias excite cavity resonances in power-ground plane pairs causing them to behave as parallel-plate waveguides. The role of interplane shorting vias in suppressing cavity resonances is then investigated and the impact of boundary conditions on the simulation results of package models is also shown and discussed. The focus is then shifted to PCB/package cosimulation and the impact of different truncation schemes is discussed through the simulation of test structures of varying complexity. A simulation methodology is then proposed and is verified for a combined model of a realistic complex multilayer package and board and it is demonstrated that accurate results can be obtained through proper truncation of the geometry.

Examination of Far-Field Mathematical Absorber Reflection Suppression through Computational Electromagnetic Simulation

The mathematical absorber reflection suppression (MARS) technique has been used to identify and then suppress the effects of spurious scattering within spherical, cylindrical, and planar near-field antenna measurement systems, compact antenna test ranges (CATRs), and far-field measurement facilities for some time now. The recent development of a general-purpose three-dimensional computational electromagnetic model of a spherical antenna test system has enabled the MARS measurement and postprocessing technique to be further investigated. This paper provides an overview of the far-field MARS technique and presents an introduction to the computational electromagnetic range model. Preliminary results of computational electromagnetic range simulations that replicate typical MARS measurement configurations are presented and discussed which, for the first time, confirm through simulation many of the observations that have previously been noted using purely empirical techniques.

The radio-frequency design of an iris-type coupler for the CPHS radio-frequency quadrupole

The Compact Pulsed Hadron Source (CPHS) project is a university-based proton accelerator platform (13 MeV, 16 kW, 50 mA peak current, 0.5 ms pulse width at 50 Hz) for multi-disciplinary neutron and proton applications. The CPHS linac consists of a 3 MeV radio-frequency quadrupole (RFQ) linac and a 13 MeV drift tube linac (DTL). Both the RFQ and DTL share a 325 MHz, 2.1 MW klystron source. A single iris-type radio-frequency (RF) coupler is used to feed 537 kW of RF power to the RFQ cavity. Three-dimensional electromagnetic models of the ridge-loaded tapered waveguide (RLWG) and the coupler-cavity system are presented, and the design process and results of the RLWG and iris plate are described in detail.

Modelling the shape, length and radiation characteristics of bond wire antennas

Novel analytical models for accurately modelling the shape and length of bond wires in dependence on the loop height (Lhmax), distance between the bonding positions (dbp) and the thickness of the metallisation (tmet.) on which the wires are bonded, are derived in this work. These analytical models, which are based on the Gaussian distribution function, are applied to (i) develop realistic three-dimensional electromagnetic models of bond wire antennas and study their radiation characteristics and (ii) study the impact of process tolerances of bond wire parameters on the performance of the antennas. For these studies, a 42 GHz half-loop bond wire antenna is considered as an example. It is designed, fabricated and measured. Our results reveal that dbp has the most significant impact on the antenna performance. For example, −10% fluctuations in dbp causes ∼2.5 GHz shift in the resonance frequency and 24% reduction in the maximum realised gain. Since this may completely detune the antenna, it is recommended that fluctuations in dbp should be kept below 10% during the manufacturing process. Good correlation is obtained between measurement and simulation results.

Optimization of Microwave Packaging Structure for Directly Modulated Laser Modules Using Three-Dimensional Electromagnetic Model

In this paper, the packaging aspects of directly modulated laser (DML) modules are investigated using detailed electromagnetic (EM) simulations. The packaging influences of the laser module are specified in two parts as RF connector and optoelectronic subsystem. By carefully optimizing the package structure, the simulation results show that the insertion loss of the proposed module is less than 1 dB up to 40 GHz. Then, a DML module is packaged and measured based on the optimized package scheme. A resonance free bandwidth of approximately 20 GHz is obtained with a 3 dB bandwidth of about 15 GHz.