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This work elaborates the transferability of electrode diffusion coefficients gained from fitting procedures in frequency domain to an electrochemical battery model run in time domain. An electrochemical battery model of an NMC622 half-cell electrode is simulated with sinusoidal current excitations at different frequencies. The current and voltage signals are analyzed in frequency domain via Nyquist and Bode plots. The frequency domain analysis of time domain simulations is applied to assess the numerical convergence of the simulation and the sensitivity on particle diameter, electrode and electrolyte diffusion coefficients. The simulated frequency spectra are used to fit the electrode diffusion coefficient by means of different electrical equivalent circuit models and the electrochemical battery model itself. The fitted diffusion coefficients from the different electrical equivalent circuit models deviate by one order of magnitude from the a priori known reference data. The fitting results from the electrochemical battery model show a perfect match and the corresponding simulation times underline the feasibility of this fitting approach. The impact of different electrode diffusion coefficients is further assessed by constant current discharge and pulse discharge simulations at different C-rates. The voltage responses deviate in the range of 20 mV for the 2C discharge pulse.

This work is devoted to the topological analysis of multi-physical networks stemming from automated modeling processes in system simulation software. A special focus is on the methodical treatment of multi-physical networks, which can be utilized to develop robust and user-friendly simulation tools. In the multi-physical case, the already available topological criteria of different physics have to be merged and reinterpreted. A general receipt for their analysis is described in terms of a representative example, a fluid-solid network which is thermally coupled. The theoretical results are put in context to a practical realization in a simulation software in terms of modeling and coupling concepts, which help to improve the useability of system simulation software for software application engineers.

This work is devoted to the analysis of multi-physics dynamical systems stemming from automated modeling processes in system simulation software. The multi-physical model consists of (simple connected) networks of different or the same physical type (liquid flow, electric, gas flow, heat flow) which are connected via interfaces or coupling conditions. Since the individual networks result in differential algebraic equations (DAEs), the combination of them gives rise to a system of DAEs. While for the individual networks existence and uniqueness results, including the formulation of index reduced systems, is available through the techniques of modified nodal analysis or topological based index analysis, topological results for coupled system are not available so far. We present an approach for the application of topological based index analysis for coupled systems of the same physical type and give the outline of this approach for coupled liquid flow networks. Exploring the network structure via graph theoretical approaches allows to develop topological criteria for the existence of solutions of the coupled systems. The conditions imposed on the coupled network are illustrated via various examples. Those results can be interpreted as a natural extensions of the topological existence and index criteria provided by the topological analysis for single connected circuits.

This work is devoted to fast and parameter-robust iterative solvers for frequency domain finite element equations, approximating the time-periodic eddy current problem with multiharmonic or time-periodic excitations in time. We construct a preconditioned MinRes solver for the frequency domain equations, that is robust with respect to the discretization parameters as well as all involved “bad” parameters like the conductivity, the reluctivity and possible regularization parameters.

SUMMARY This work is devoted to the multiharmonic analysis of parabolic optimal control problems in a time-periodic setting. In contrast to previous approaches, we include the cases of different control and observation domains, the observation in certain energy spaces, and the presence of control constraints. In all these cases, we propose a new preconditioned MinRes solver for the frequency domain equations and show that this solver is robust with respect to the space and time discretization parameters as well as the involved ‘bad’ model parameters of the state equation. Copyright © 2012 John Wiley & Sons, Ltd.

This work is devoted to the construction and analysis of robust solvers for some distributed optimal control problems for time-periodic eddy current problems. We apply the multiharmonic approach to the optimality system and construct a new preconditioned MinRes solver for the system of frequency domain equations. We show that this solver is robust with respect to the space discretization and time discretization parameters as well as all involved “bad” parameters, like the conductivity, the reluctivity, and the regularization and cost parameters.

In this paper, we present and discuss the results of our numerical studies of preconditioned MinRes methods for solving the optimality systems arising from the multiharmonic finite element approximations to time-periodic eddy current optimal control problems in different settings including different observation and control regions, different tracking terms, as well as box constraints for the Fourier coefficients of the state and the control. These numerical studies confirm the theoretical results published by the first author in a recent paper.

This paper is devoted to the construction and analysis of robust solution techniques for time-harmonic eddy current problems in unbounded domains. We discretize the time-harmonic eddy current equation by means of a symmetrically coupled finite and boundary element method, taking care of the different physical behavior in conducting and non-conducting subdomains, respectively. We construct and analyse a block-diagonal preconditioner for the system of coupled finite and boundary element equations that is robust with respect to the space discretization parameter as well as all involved “bad” parameters like the frequency, the conductivity and the reluctivity. Block-diagonal preconditioners can be used for accelerating iterative solution methods such like the Minimal Residual Method.

The paper is devoted to fast iterative solvers for frequency-domain finite element equations approximating linear and nonlinear parabolic initial boundary value problems with time-harmonic excitations. Switching from the time domain to the frequency domain allows us to replace the expensive time-integration procedure by the solution of a simple linear elliptic system for the amplitudes belonging to the sine- and to the cosine-excitation or a large nonlinear elliptic system for the Fourier coefficients in the linear and nonlinear case, respectively. The fast solution of the corresponding linear and nonlinear system of finite element equations is crucial for the competitiveness of this method.