Search

The Partial Element Equivalent Circuit (PEEC) method is promising numerical technique for three-dimension electromagnetic modeling across various application fields. In the framework of the PEEC method, the partial elements modeling the magnetic and electric field coupling between elementary volumes and surfaces are computed by double-folded volume and surface integrals. Assuming the quasi-static hypothesis and an orthogonal mesh, the integrals have been computed by the analytical formulas derived in literature, which significantly reduces the computational time in comparison to the numerical integration. However, the existing analytical formulas are affected by significant numerical errors for certain PEEC structural mesh necessary to model the skin and proximity effects with a higher accuracy. To utilize the full potential of the PEEC method, the calculation of partial elements has to be carefully addressed, which has not been investigated in a comprehensive way so far. Accordingly, this paper presents a systematic accuracy analysis of the existing closed-form analytical formulas and methods for calculating the self and mutual inductances between two rectangular conductors. Additionally, a new strategy to select a proper analytical formula depending on the dimensions and positions of two conductors is proposed, which allows the mutual inductance extraction with a relative error of less than 0.1 $\%$. The new method is systematically validated on examples of 3-D dense PEEC systems using the quadruple precision arithmetic as reference. [ABSTRACT FROM AUTHOR]

Composite materials reinforced with woven conductive fibers can be good candidates for electromagnetic shielding applications. Their light weight provides an important advantage over metallic alloys classically used in the automotive and aircraft industries. However, numerical modeling of composite-based large-scale structures, such as shielding enclosures, is rendered almost impossible by the heterogeneities at the microscopic scale. This problem is commonly addressed using electromagnetic homogenization methods. In this paper, we propose a homogenization technique based on finite element computations and inverse problem solving for estimating the effective properties of woven composites. The effect of electrical contacts between the fibers is also studied and its influence on the global behavior of the material is analyzed. The results are then shown to diverge from those obtained using analytical mixing rules over the frequency range of 1–40 GHz. Thus the suitability of these homogenization methods is discussed with respect to the studied frequency range and the nature of the microstructure. [ABSTRACT FROM AUTHOR]

To date, the development of valid and globally universally accepted recognized methods for the accurate exposure assessment of wireless power transfer (WPT) technologies is lagging behind the rapid emergence of high power systems in the energy and automotive sectors. WPT systems based on inductive and magnetic resonance technologies generate strong but rapidly decaying magnetic fields, which often exceed reference levels (RL) in the immediate vicinity of the WPT coils by up to a factor of $>$ 100. Compliance testing of WPT systems with limits derived for homogeneous exposure can lead to estimations of exposure that exceed by up to 40 dB assessments of the fields induced in the human body, i.e., the basic restrictions (BR) defined by the international safety guidelines. Testing compliance with the BR is impractical for regulatory purposes due to the high costs of resources of determining the maximum exposure conditions. This paper presents a novel compliance testing method that mitigates the overestimation of the exposure while maintaining the simplicity of the testing procedure. This is achieved by using coupling transformation functions to correlate not only the amplitude and frequency but also the gradient of the incident field with the BR. These novel conservative coupling functions have been determined by means of a large scale numerical study in the frequency range 3 kHz–10 MHz supported by a physics-based approximation. The here proposed compliance testing method is still conservative in comparison to the compliance toward BR of localized sources. However, in comparison to today's practice of applying RL directly, the overestimation is strongly reduced for high gradient fields ($G_n$ $>$ 50 T/m/T), e.g., by more than 3000 times for field gradients of about 200 T/m/T. We have validated the method by numerical analysis of human exposure to actual WPT sources. The adoption of the new method will help to accelerate the introduction of high-power wireless charging devices in the global market. [ABSTRACT FROM AUTHOR]

This paper presents a study on strategies of searching for the worst case configuration of a multi-configuration implantable system under magnetic resonance imaging, which induces the highest radio frequency energy exposure among all possible configurations. The strategies are usually based on parameter search to avoid brutal study of a huge number of possible configurations. Comparison studies of four different searching strategies, i.e., single sequential search, sequential search with the second worst case validations, hotspots-based sequential search, and multi-iteration sequential search, are evaluated. It is found that the initial configuration and sequence of parameter search can significantly affect the searched worst case configuration. For the multi-configuration system considered in this investigation, the simple sequential search strategy leads to a high probability of search failure, which means that the worst case configuration may be easily missed. Single sequential search with the second worst case validations and multi-iteration sequential search can significantly reduce the probability of search failure. [ABSTRACT FROM AUTHOR]

This paper focuses on rigorous validation, verification, and testing methodologies applied to a commercial electromagnetic software package to ensure that as accurate as possible results are given dependent on the accuracy of the solution method, for instance, whether a full-wave or approximate numerical method is used. In this paper, the general availability of reliable benchmark results such as analytical solutions, measurements, results from other codes and other numerical methods, and general benchmarking activities will be presented. The cross-validation aspects, once the benchmark results are available, will be discussed with respect to amongst other sequential runs compared with parallel multcore/cluster runs or, with and without, GPU acceleration. Internal consistency checks (which are a required but not necessary condition when assessing the accuracy) such as power budget, mesh size convergence, or boundary condition error estimates are also covered. Special emphasis is put on the validation of the actual computational model that is used as input to simulations. This is necessary, for example, because incomplete representation of real geometry might ignore small details that are needed for the specific quantity that is analyzed. Also, uncertainties with regards to material parameters or transition impedances could lead to discrepancies between the computed results and reality that are not to be attributed to the electromagnetic solution as such, but rather the model generation. [ABSTRACT FROM PUBLISHER]

In this paper, we adopt the so-called sparse polynomial chaos metamodel for the uncertainty quantification in the framework of high-dimensional problems. This metamodel is used to model a realistic electronic bus structure with a large number of uncertain input parameters such as those related to microstrip line geometries. It aims at estimating quantities of interest, such as statistical moments, probability density functions, and provides sensitivity analysis of a response. It drastically reduces the model computational cost with regard to brute force Monte Carlo (MC) simulation. The method presents a good performance and is validated in comparison with MC simulation. [ABSTRACT FROM AUTHOR]

The problem of a correct modeling of the electromagnetic field distribution in the near field region is one of the most challenging and interesting due to its direct implication in the engineering evaluation of the shielding effectiveness of materials and structures in close proximity of radiating sources. This paper deals with a detailed analysis on the applicability of the Schelkunoff theory of transmission lines for shielding assessment in near field. The contribution is divided in two Parts. The present Part I analyzes the characteristics of two principal closed form set of equations for the quick evaluation of the near field from an electric dipole. It discusses their assumptions and compares the values of electric (E) and magnetic (H) fields, and their statistics, with those coming from accurate three-dimensional full waves simulations considered as reference. The computed E and H are the input for Part II where the wave impedance and the reflection, transmission, and shielding effectiveness coefficients are computed and discussed. [ABSTRACT FROM AUTHOR]

Field uniformity is a highly important factor in guaranteeing the validity of test results for electromagnetic field facilities. In this paper, an alternative method is presented to calibrate field uniformity for eliminating the measurement error due to the variability of pulser outputs. By numerical computation and practical measurement, it is found that the method is beneficial to calibrate field uniformity of transient electromagnetic field faster and more accurately. [ABSTRACT FROM AUTHOR]

This paper focuses on parameter uncertainty quantification (UQ) in specific absorption rate (SAR) calculation using a computer-aided design mobile phone model. The uncertainty in SAR calculation is quantified by three nonintrusive UQ methods: unscented transformation, stochastic collocation, and nonintrusive polynomial chaos. Their performances for the cases of one and two random variables are analyzed. To simplify the UQ procedure for the case of multiple uncertain inputs, it is demonstrated that uncertainties can be combined to evaluate the parameter uncertainty of the output. To quantify the relative importance of each uncertain input parameter with respect to the uncertainty of the output, the polynomial chaos based Sobol’ indices method is used in SAR calculation for sensitivity analysis. The results of the investigations are presented and discussed. [ABSTRACT FROM PUBLISHER]

In this paper, reliability analysis is applied to assess electromagnetic risk due to external electromagnetic waves in a coaxial shielded cable. Generally, the classical sampling method—Monte Carlo (MC)—is used to conduct thousands or millions of runs of the numerical model. As this latter is time-demanding, the computational cost becomes prohibitive. As an alternative, an advanced metamodeling method based on Kriging is proposed for efficiently assessing small failure probabilities. This method is called AK-MCS. It consists in an active learning reliability method combining Kriging and MC simulation. Metamodeling reduces the computational run time by replacing the true numerical model by an inexpensive surrogate model. The interpolated surrogate model presents the advantage to be rapidly handled by MC simulations to calculate the failure probability. AK-MCS method is based on an adaptive strategy to enrich the design of experiments (DOE) with significant sampling points near the failure region, and hence, Kriging model is ameliorated and so is the assessment of failure probability. Three numerical examples of radiated susceptibility in a shielded cable are conducted to demonstrate the efficiency of the underlined Kriging approach. Reliable metamodels can be obtained through a small number of runs of the true numerical model, and it is found that the computed failure probabilities are very accurate compared to crude MC simulation results. [ABSTRACT FROM AUTHOR]

This paper deals with the use of the Bayesian approach to inverse an underdetermined magnetostatic problem based on spherical harmonic expansion. Identification of the spherical harmonic coefficients is helped thanks to some a priori information. This information comes from a numerical model statistically studied to define an average-state vector and a covariance matrix. The whole approach is applied for the study of the magnetostatic field inside an electric vehicle, created by its power circuitry. It demonstrates the strength of merging a priori information and measured information in order to obtain an efficient identification of magnetic sources created by a complex set of conductors. [ABSTRACT FROM AUTHOR]

This paper presents a two-dimensional discontinuous Galerkin time-domain (2-D DGTD) method for modeling arbitrarily shaped power-ground planes in high-speed electronics. The DGTD method has advantage over the finite-difference time-domain method in handling complex geometries, and allows high-order spatial discretization for improved accuracy. Its explicit time-stepping scheme also reduces computational cost compared to the implicit finite element time-domain method. The proposed method is validated against both measurement and commercial software to demonstrate its accuracy and efficiency. [ABSTRACT FROM AUTHOR]

This paper proposes a numerical solution of the nonlinear equations that describes the hysteretic behavior of ferromagnetic materials. From the proper definition and solution of these equations, an equivalent circuit model for a ferromagnetic core is developed and proposed. The results obtained from the equivalent circuit are compared with those obtained by a rigorous numerical solution. [ABSTRACT FROM AUTHOR]

In this paper, we show the application of numerical simulation for the virtual testing of a very complex system under high-intensity radiated fields (HIRF) conditions. Numerical results have been compared to measurements performed on a C-295 aircraft. The approach is based on the use of multiple tools for the preprocessing, computation, and postprocessing, all of them integrated under the same framework. This study is a part of the HIRF SE project, and the final step for the validation of the tools involved there, to introduce the use of simulation in the whole aircraft certification process in an HIRF environment. The main goal of the project is to provide the aeronautic industry with a numerical modeling computing framework, which could be used to predict the electromagnetic performance, and to carry out parametrical studies during the design phase, when changes are simpler and less costly. It could also lead in the future to a considerable reduction on the certification/qualification testing phase on air vehicles, to cross validate the results obtained from measurement and simulation providing best confidence in them, and to attain a more exhaustive analysis to achieve a higher level in the air vehicle safety. [ABSTRACT FROM PUBLISHER]