41 citations · 177 across the 26 of their papers we have counts for
20 papers · 1 filter
A Regularized Ensemble Kalman Filter for Stochastic Phase Field Models of Brittle Fracture
Lucas Hermann, Ralf Jänicke, Knut Andreas Meyer +1
The phase-field approach to brittle fracture provides a continuum framework for modeling crack initiation and propagation without explicit representation of discrete crack surfaces…
Statistical reduced order modelling for the parametric Helmholtz equation
Lucas Hermann, Matthias Bollhöfer, Ulrich Römer
Predictive modeling involving simulation and sensor data at the same time, is a growing challenge in computational science. Even with large-scale finite element models, a mismatch…
Reduced and All-at-Once Approaches for Model Calibration and Discovery in Computational Solid Mechanics
Ulrich Römer, Stefan Hartmann, Jendrik-Alexander Tröger +4
In the framework of solid mechanics, the task of deriving material parameters from experimental data has recently re-emerged with the progress in full-field measurement capabilitie…
Rational kernel-based interpolation for complex-valued frequency response functions
Julien Bect, Niklas Georg, Ulrich Römer +1
This work is concerned with the kernel-based approximation of a complex-valued function from data, where the frequency response function of a partial differential equation in the f…
Inferring Displacement Fields from Sparse Measurements Using the Statistical Finite Element Method
Vahab B. Narouie, Henning Wessels, Ulrich Römer
A well-established approach for inferring full displacement and stress fields from possibly sparse data is to calibrate the parameter of a given constitutive model using a Bayesian…
An -adaptive multi-element stochastic collocation method for surrogate modeling with information re-use
Armin Galetzka, Dimitrios Loukrezis, Niklas Georg +2
This paper introduces an -adaptive multi-element stochastic collocation method, which additionally allows to re-use existing model evaluations during either - or -refinem…
Conformally Mapped Polynomial Chaos Expansions for Maxwell's Source Problem with Random Input Data
Niklas Georg, Ulrich Römer
Generalized Polynomial Chaos (gPC) expansions are well established for forward uncertainty propagation in many application areas. Although the associated computational effort may b…
Stochastic phase-field modeling of brittle fracture: computing multiple crack patterns and their probabilities
Tymofiy Gerasimov, Ulrich Römer, Jaroslav Vondřejc +2
In variational phase-field modeling of brittle fracture, the functional to be minimized is not convex, so that the necessary stationarity conditions of the functional may admit mul…
Yield Optimization based on Adaptive Newton-Monte Carlo and Polynomial Surrogates
Mona Fuhrländer, Niklas Georg, Ulrich Römer +1
In this paper we present an algorithm for yield estimation and optimization exploiting Hessian based optimization methods, an adaptive Monte Carlo (MC) strategy, polynomial surroga…
Uncertainty Modeling and Analysis of the European X-ray Free Electron Laser Cavities Manufacturing Process
Jacopo Corno, Niklas Georg, Shahnam Gorgi Zadeh +9
This paper reports on comprehensive efforts on uncertainty quantification and global sensitivity analysis for accelerator cavity design. As a case study object the TESLA shaped sup…
Coupled Simulation of Transient Heat Flow and Electric Currents in Thin Wires: Application to Bond Wires in Microelectronic Chip Packaging
Thorben Casper, Ulrich Römer, Sebastian Schöps +1
This work addresses the simulation of heat flow and electric currents in thin wires. An important application is the use of bond wires in microelectronic chip packaging. The heat d…
Enhanced adaptive surrogate models with applications in uncertainty quantification for nanoplasmonics
Niklas Georg, Dimitrios Loukrezis, Ulrich Römer +1
We propose an efficient surrogate modeling technique for uncertainty quantification. The method is based on a well-known dimension-adaptive collocation scheme. We improve the schem…
A multilevel Monte Carlo method for high-dimensional uncertainty quantification of low-frequency electromagnetic devices
Armin Galetzka, Zeger Bontinck, Ulrich Römer +1
This work addresses uncertainty quantification of electromagnetic devices determined by the eddy current problem. The multilevel Monte Carlo (MLMC) method is used for the treatment…
Assessing the Performance of Leja and Clenshaw-Curtis Collocation for Computational Electromagnetics with Random Input Data
Dimitrios Loukrezis, Ulrich Römer, Herbert De Gersem
We consider the problem of quantifying uncertainty regarding the output of an electromagnetic field problem in the presence of a large number of uncertain input parameters. In orde…
Recent Advances of Isogeometric Analysis in Computational Electromagnetics
Zeger Bontinck, Jacopo Corno, Herbert De Gersem +8
In this communication the advantages and drawbacks of the isogeometric analysis (IGA) are reviewed in the context of electromagnetic simulations. IGA extends the set of polynomial…
Multilevel Monte Carlo Simulation of the Eddy Current Problem With Random Parameters
Armin Galetzka, Zeger Bontinck, Ulrich Römer +1
The multilevel Monte Carlo method is applied to an academic example in the field of electromagnetism. The method exhibits a reduced variance by assigning the samples to multiple mo…
Low-Dimensional Stochastic Modeling of the Electrical Properties of Biological Tissues
Ulrich Römer, Christian Schmidt, Ursula van Rienen +1
Uncertainty quantification plays an important role in biomedical engineering as measurement data is often unavailable and literature data shows a wide variability. Using state-of-t…
Modeling of Spatial Uncertainties in the Magnetic Reluctivity
Radoslav Jankoski, Ulrich Römer, Sebastian Schöps
In this paper a computationally efficient approach is suggested for the stochastic modeling of an inhomogeneous reluctivity of magnetic materials. These materials can be part of el…
High Dimensional Uncertainty Quantification for an Electrothermal Field Problem using Stochastic Collocation on Sparse Grids and Tensor Train Decompositions
D. Loukrezis, U. Römer, T. Casper +2
The temperature developed in bondwires of integrated circuits (ICs) is a possible source of malfunction, and has to be taken into account during the design phase of an IC. Due to m…
Determination of Bond Wire Failure Probabilities in Microelectronic Packages
Thorben Casper, Ulrich Römer, Sebastian Schöps
This work deals with the computation of industry-relevant bond wire failure probabilities in microelectronic packages. Under operating conditions, a package is subject to Joule hea…