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The purpose of this paper is to present a time domain discontinuous Galerkin (DG) approach for modeling wideband frequency dependent surface impedance boundary conditions.

The paper solves the Maxwellian initial value problem in a computational domain, which is spatially discretized by the higher order DG method. On the boundary of the computational domain the paper applies a suitable impedance boundary condition (IBC). The frequency dependency of the impedance function is modeled by auxiliary differential equations (ADE).

The authors will study the resonance frequency and the Q factor of different types of cavity resonators including lossy materials. The lossy materials are modeled by means of IBCs. The authors will compare the results with analytical results, as well as numerical results obtained by direct calculations where lossy materials are included explicitly into the numerical model. Several convergence studies are performed which demonstrate the accuracy of the approach.

Modeling of frequency dependent boundary conditions in time domain with finite difference time domain method (FDTD) method is considered in numerous papers, as well as in frequency domain finite element method (FEM), and in a few papers also time domain FEM. However, FDTD method is only first order accurate and fails in modeling of complicated surfaces. FEM allows for high order accuracy, but time domain modeling is numerically extremely expensive. In frequency domain, broadband modeling of frequency dependent boundary conditions requires several simulations as opposed to the time domain, where a single simulation is needed. The time domain DG method proposed in this paper allows to overcome the difficulties. The authors introduce a broadband surface impedance formulation based on the ADE approach for the higher order DG method.

Certain sophisticated boundary conditions offer powerful modelling features for many electrotechnical models. Their application, however, wipes out the particular structure of the system matrices which occurs when structured grids are applied. In this paper, this effect is prevented by considering the unconstrained system together with additional constraint equations or by projecting the algebraic system using an oblique or orthogonal projector. The numerical tests indicate that the efficiency of sparse iterative solvers can be preserved even in the presence of complicated boundary relations. The described projections are also advantageous for formulations derived for unstructured grids.

The sliding‐surface and moving‐band techniques are introduced in frequency‐domain finite element formulations to model the solid‐body motion of the rotors in an cylindrical machine. Both techniques are compared concerning their feasibility and computational efficiency. A frequency‐domain model of a capacitor motor is equipped with a sliding surface and compared to a transient model with moving band. This example illustrates the advantages of frequency‐domain simulation over transient simulation for the simulation of steady‐state working conditions of electrical machines.

The purpose of this paper is to offer a fast and accurate simulation method for printed spiral radio frequency identification coils and to extract the parameters of an equivalent resonance circuit.

The frequency‐dependent port impedance of a rectangular spiral multi‐turn antenna is simulated with the non‐retarded partial element equivalent circuit (PEEC) method. The discretization settings needed for an accurate modeling of skin and proximity effects at medium frequencies as well as parasitic capacitances are discussed. Two different PEEC approaches are used, a magneto‐quasi‐static (resistive and inductive cells) model and a non‐retarded (capacitive cells included) model in order to extract a reduced equivalent resonance circuit which is beneficial to describe the inductive coupling to further inductors via the transformer concept.

With optimized mesh settings, the extremely fast simulation can be carried out just in seconds whereas the results compared to a computationally much more expensive CST Microwave Studio^® reference solution as well as an analytical direct current solution show errors of only about a few percent.

The methodology is limited to frequencies up to the first self‐resonant frequency of the coil. In addition, piecewise‐homogeneous materials are implied.

Specialized mesh settings allow for a very fast and accurate simulation of rectangular spiral inductors. A method for the parameter extraction of a resonance circuit is proposed by evaluating two different PEEC models.

To provide a reliable numerical technique for the time integration of the electromagnetic models with sinusoidal excitation.

The numerical integration of an electrotechnical problem is commonly carried out using adaptive time stepping. For one particular selected time step, Runge‐Kutta (RK) adaptive integration methods deliver two approximations to the solution with different order of approximation. The difference between both is used to estimate the local error.

Standard error‐controlled RK time integration fails for electromagnetic problems with sinusoidal excitation when the adaptive time step selection relies upon the comparison of a main solution and an embedded solution where the difference of orders is one. This problem is overcome when the embedded solution differs by two orders of approximations. Such embedded solution is efficiently constructed by putting appropriate order conditions on the coefficients of the Butcher table.

Using the technique proposed in the paper, electromagnetic problems with sinusoidal dynamics can also be effectively tackled.

The purpose of this paper is to propose a transmission line model for induction machines, which serves to compute the common mode input impedance in the frequency range 10 Hz-1 MHz.

Special diligence is attributed to the modelling of eddy currents inside the core lamination. In order to determine the transmission line parameters accurately, two modelling approaches are compared. The first is a two-dimensional simulation approach where iron core lamination effects are included by means of an equivalent material approximation. The second approach consists in fully three-dimensional analysis taking into account explicitly the eddy currents induced in the laminations.

It is shown that homogenised equivalent material models may lead to large errors in the calculation of machine inductances, especially at high frequencies. However, the common mode input impedance, which is the final parameter of interest, seems to be less affected by the lamination modelling.

The paper compares different analytical and numerical approaches in the frequency range 10 Hz-1 MHz and tries to give benchmarks for errors which occur due to a number of commonly used model simplifications.

The purpose of this paper is to offer a simulation method for predicting the impedance of machine windings at higher frequencies.

A transmission‐line model (TLM) is developed based on parameters calculated on the basis of electroquasistatic and magnetoquasistatic finite‐element (FE) model of the winding cross‐section.

The FE formulations for the low‐ and high‐frequency limits give acceptable results for the respective frequency ranges. An eddy‐current formulation is only accurate on a broader region when the FE mesh is sufficiently fine to resolve the skin depth.

The paper is restricted to frequency‐domain simulations.

The results of the paper improve the understanding of higher‐frequency parasitic effects in electrical drives with long windings.

The paper shows the limitations of the FE methods used for determining the parameters of the TLMs and remedies to avoid these.

The purpose of this paper is to clarify the role of American culture in social foresight as practiced by American futurists. It also seeks to describe how American culture has been expropriated by corporate culture, which is global. Finally, the paper seeks to depict various scenarios of the future of the USA and to consider an imperative of the futurist to reform the role of the professional futurist consultant in the capacity of social foresight that sets as its chief aim the transformation of business practice towards a sustainable, restorative economy.

The paper is a critical approach to American and corporate culture by exposing major assumptions behind business ideology and practice. It also applies the same critical approach to the way futures has been practiced within the capitalist paradigm during the past 50 years. It is a civilisational critique that also points towards an integral solution for sustainable, restorative business practice.

It was found that superficial efforts at sustainable solutions will not be enough to manage the impending collapse of industrial civilization. What is required is a wholesale transformation that is indicative of a paradigm shift towards a natural capitalism in which business practice is totally guided by sustainability and restoration of the natural systems rather than mere, narrowly focused “bottom line” ideology. It finds that social foresight can play a positive role in directing this transition and crisis of humanity.

Hopefully, the paper will contribute to the progress of futures towards a more specifically focused matter of social foresight. It should help futurists to recognize their leadership role, which should guide business entrepreneurs and social innovation towards the realization of sustainability and restoration. At the same time, it emphasizes the need to embrace rather than shun activism, to link with other progressives who seek to redefine the relationship of government and business through democratic means. The paper emphasizes the need to protect and restore a future that is being systematically undermined and destroyed.

The numerical solution of electromagnetic field nonlinear problems requires successive building and solving of linear systems of equations. This is the most time–consuming part, especially for large problems. Both fast linear solvers and efficient nonlinear iterative algorithms, are critical for the overall efficiency of the nonlinear electromagnetic field solver. This paper presents an analysis of a variety of techniques that can be efficiently used to reduce the solution time of nonlinear magnetic field equations in large finite element method (FEM) problems.

This study explains the variation of government responses to the pandemic by focusing on how centralization/decentralization in politics and administration creates conflicts and coordination problems. Specifically, the authors make comparisons between the U.S. and South Korea to reveal differences in macro-level structures and associated responses. One of the key points of comparison is the centralized, hierarchical governance system, which may thwart or facilitate a coordinated response.

This is an in-depth comparative case study of the two countries that showed different trajectories during the initial response to COVID-19. The comparison allows us to highlight the long-standing debate about centralization/decentralization and offers implications for government responses to crises shaped by political systems and administrative structures.

While there are inherent pros and cons to decentralization, the COVID-19 pandemic highlights the institutional limitations in American federalism and the advantages that centralized administrative coordination creates during times of crisis. American federalism has unveiled systematic problems in coordination, along with the leadership crisis in polarized politics. The response from South Korea also reveals several issues in the administratively centralized and politically polarized environment.

While the authors risk comparing apples and oranges, the variation unveils systematic contradictions in polarized politics and offers important implications for government responses in times of crisis. However, this article did not fully account for individual leadership as an independent factor that interacts with existing political/administrative institutions.

There is certainly no one best way or one-size-fits-all solution to mitigating the COVID-19 pandemic in countries under different circumstances. This article demonstrates that one of the essential determining factors in national responses to the pandemic is how the political and administrative dimensions of centralization/decentralization are balanced against each other.

Unlike previous studies explaining the country-level responses to COVID-19, this study focuses on the variance of political and administrative decentralization within each country from the political-administrative perspective and reveals the systematic contradictions in coordination and the leadership crisis in polarized politics.