Together with the Computational Engineering Research Center of the TU Darmstadt a joint seminar with interesting talks in the field of CE is organized in every semester. If you are interested in these seminars and would like to receive invitations please subscribe for the corresponding mailing list.

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2018-01-15

5 Feb 2018, 16:15–17:45; Location: S2|17-103

Quasistatic electromagnetic field models are considered for situations, where the shortest wave length of a problem exceeds the spatial dimensions of the problem by at least one order of magnitude. A taxonomy of such quasistatic field models distinguishes between the electro-quasistatic, the magneto-quasistic and the so-called Darwin field models. These ... [more] »

Category: CE Seminar

2017-12-15

16 Jan 2018, 17:00–18:30; Location: S4|10-1

We study sparse solutions of optimal control problems governed by elliptic PDEs with uncertain coefficients. Sparsity of controls is achieved by incorporating the \(L^1\)-norm of the mean of the pointwise squared controls in the objective. Two optimal control formulations are proposed, one where the solution is a deterministic control that optimizes ... [more] »

Category: CE Seminar

2017-12-04

18 Dec 2017, 16:15–17:45; Location: S2|17-103

While waveform relaxation methods converge for coupled ODE systems, they may suffer from instabilities for coupled differential-algebraic equations (DAEs). Whereas several convergence criteria are known for index-1 DAEs, we present here a convergence criterion for quasilinear index-2 DAEs for the first time. It applies to systems of coupled ODE/circuit ... [more] »

Category: CE Seminar

2017-10-18

23 Oct 2017, 16:30–18:00; Location: S2|02-C110

Since 2011 the EU Mont-Blanc project pushes the development of ARM-based compute platforms, following the vision of leveraging the fast growing market of mobile technology for performing scientific computation. The process started almost 5 years ago with the development of prototypes based on Android dev-kits and is now evolving beyond the research project, ... [more] »

Category: CE Seminar

2017-09-26

6 Oct 2017, 14:00–15:30; Location: S2|17-103

Category: CE Seminar

2017-09-06

11 Sep 2017, 16:30–18:00; Location: S2|17-103

The Linac Coherent Light Source is a linac-based, X-ray free electron laser (FEL) at the SLAC National Accelerator Laboratory. It accelerates single bunches up to 4--13 GeV before sending them to the undulator for lasing. A project is underway to run the LCLS bunches in trains, with up to initially four and later eight bunches in a train. Bunch trains will ... [more] »

Category: CE Seminar

2017-02-21

20 Jul 2017, 17:00–18:30; Location: S4|10-1

For more than thirty years it was thought that the efficient construction of pressure-robust mixed methods for the incompressible Navier-Stokes equations, whose velocity error is pressure-independent, was practically impossible. However, a novel, quite universal construction approach shows that it is indeed rather easy to construct pressure-robust mixed ... [more] »

Category: CE Seminar

2017-05-10

18 Jul 2017, 17:00–18:30; Location: S4|10-1

The presentation summarizes progress made over the past few years in the calculation of spectral bounds of interval Hessian matrices. Spectral bounds of this type play an important role in global optimization algorithms. They can be used, for example, to detect if a given optimization problem is convex, or to generate a convex relaxation in case it is not. ... [more] »

Category: CE Seminar

2017-06-21

17 Jul 2017, 16:15–17:45; Location: S2|17-103

The numerical computation of small probabilities of failure for a system is a notoriously difficult problem, and the Subset Simulation algorithm of Au & Beck (Prob. Eng . Mech., 2001) has become one of the most popular method to solve it. Subset simulation has been shown to provide significant savings in the number of evaluations of the performance ... [more] »

Category: CE Seminar

2017-04-03

10 Jul 2017, 16:30–18:00; Location: S2|02-C110

Parallel programming for large scale computer architectures is a complex and error-prone task. Automatic tools can assist application developers in the detection and removal of such errors. This talk will present the scalable runtime tool MUST, the methods behind the tool (graph analysis, push down automaton) and the limitations that ... [more] »

Category: CE Seminar

2017-05-08

3 Jul 2017, 16:15–17:45; Location: S2|17-103

We investigate methods of topology and shape optimization for an optimal design problem from electrical engineering which is constrained by the quasilinear PDE of two-dimensional magnetostatics. We derive the topological derivative of the objective function, i.e., its sensitivity with respect to a topological perturbation of the domain, and compare it to ... [more] »

Category: CE Seminar

2017-06-16

30 Jun 2017, 10:00–11:30; Location: S3|05-074 (Fraunhofer IGD)

In this talk, we will give an introduction to Integer Programming (IP) and show how we used IP in recent research projects. The projects range from problem formulations in visualization to urban modeling. The talk will focus mainly on the modeling side of integer programming, i.e. how to formulate a given problem as integer ... [more] »

Category: CE Seminar

2017-05-22

26 Jun 2017, 15:00–16:15; Location: S2|02-B002 (Piloty building)

Cyber-physical systems (CPS) combine cyber aspects such as communication and computer control with physical aspects such as movement in space, which arise frequently in many safety-critical application domains, including aviation, automotive, railway, and robotics. But how can we ensure that these systems are guaranteed to meet their design goals, e.g., ... [more] »

Category: CE Seminar

2017-05-08

8 Jun 2017, 17:00–18:30; Location: S4|10-1

The basic idea of model order reduction utilizing proper orthogonal decomposition (POD-MOR) consists in replacing a high-dimensional problem by a low-dimensional POD approximation with the aim to save computational times and storage capacity while preserving a good approximation quality. Following the idea of Sirovich (1987), the POD surrogate models are ... [more] »

Category: CE Seminar

2017-04-03

1 Jun 2017, 17:00–18:30; Location: S4|10-1

Protection and sustainable management of water resources is one of the key problems in environmental engineering. In this aspect, accurate modeling and simulating coupled ground and surface water flows is a necessity. Chemically reactive components such as dissolved minerals, colloids, or contaminants are transported by advection and diffusion over long ... [more] »

Category: CE Seminar

2017-05-23

29 May 2017, 14:00–15:30; Location: S4|14-5.3.01

Since the beginning of "high-performance" parallel computing, observing and analyzing performance for purposes of finding bottlenecks and identifying opportunities for improvement has been at the heart of delivering the performance potential of next-generation scalable systems. Interestingly, it is the ever-changing parallel computing landscape ... [more] »

Category: CE Seminar

2017-05-09

22 May 2017, 16:15–17:45; Location: S2|17-103

Nanohelices with pitch and diameter as characteristic dimensions of the order of 100 nm are formidable systems to investigate optical and electronic properties of matter on the nanoscale. Their unique helical structure on the nanoscale is the source of a range of unconventional properties. In the present work, first the production process of the ... [more] »

Category: CE Seminar

2017-02-23

24 Apr 2017, 16:15–17:45; Location: S2|17-103

To date, there is a large literature on non-overlapping domain decomposition (DD) methods for acoustic and electromagnetic wave problems. For some of these methods, the domain decomposition is tightly coupled to the formulation and makes it difficult to understand. In this talk (based on joint work with Timo Euler, CST AG), we develop a unified DD ... [more] »

Category: CE Seminar

2017-01-05

13 Mar 2017, 16:15–17:45; Location: S2|17-103

We present some attempts at improving the accuracy and efficiency of the reference numerical methods presently employed to model charged particle motion in magnetic quadrupoles. We first introduce the standard technique used to reconstruct the quadrupole magnetic vector potential, based on general solutions of the Laplace equation in cylindric coordinates. ... [more] »

Category: CE Seminar

2017-01-23

20 Feb 2017, 16:30–18:00; Location: S2|02-C110

High performance computing (HPC) systems are nowadays large, consist of diverse components, and exhibit massive parallelism. Exploiting the available hardware parallelism is notoriously challenging, in part due to difficulty in exposing and expressing parallelism in the computational applications. Loops are considered the main source of parallelism in most ... [more] »

Category: CE Seminar

2017-01-12

13 Feb 2017, 16:30–18:00; Location: S2|02-C120

Parallel file systems (PFS) have been developed to support typical HPC applications, where most file system operations include reading or writing huge chunks of data, which can be easily striped over the storage backend. New data-intensive applications will change these patterns and small random I/Os will occur more frequently in HPC, missing the sweet-spot ... [more] »

Category: CE Seminar

2017-01-05

30 Jan 2017, 16:15–17:45; Location: S2|17-103

For time-dependent partial differential equations, parallel-in-time integration using the "parallel full approximation scheme in space and time" (PFASST) is a promising way to accelerate existing space-parallel approaches beyond their scaling limits. Inspired by the classical Parareal method and non-linear multigrid ideas, PFASST allows to integrate ... [more] »

Category: CE Seminar

2016-11-15

12 Jan 2017, 17:00–18:30; Location: S4|10-1

The aerodynamics of flying insects is a field of research currently receiving much attention from a broad, interdisciplinary community of researchers. Their motivation ranges from the design of bio-inspired robots to fundamental questions in biology and fluid mechanics. Insects are known to produce a surprising amount of force, using comparatively small ... [more] »

Category: CE Seminar

2016-10-20

14 Nov 2016, 16:15–17:45; Location: S2|17-103

We consider linear and time-invariant partial differential-algebraic equations and show that these can be represented as differential-algebraic equations on infinite-dimensional Banach spaces. We will discuss solution theory, decoupling and control by means of several examples in flow and electric circuit theory. [more] »

Category: CE Seminar

2016-09-26

8 Nov 2016, 17:00–18:30; Location: S4|10-1

We will discuss the modelling and simulation of generalized Stefan problems to describe phase-change processes in water ice. An idealized mathematical system for the classical Stefan problem consists of two free-boundary second-order partial differential equations for both the solid, and the liquid phase. The system is closed by assuming local energy ... [more] »

Category: CE Seminar

2016-08-25

22 Sep 2016, 10:00–11:00; Location: S2|02-C110

Although data-parallelism is ubiquitous in high-performance computing (HPC) algorithms, many algorithms in other areas such as graph analytics, machine learning, and VLSI placement and routing exhibit a more complex kind of parallelism that called "amorphous data-parallelism." In this talk, I describe a simple programming model called the ... [more] »

Category: CE Seminar

2016-09-26

12 Sep 2016, 16:15–17:45; Location: S2|17-103

Abstract: An experimental study is presented that uses a corrugated structure as a passive “dechirper”— i.e. as a device for removing energy chirp — in a high energy (4.4 ‐ 13.3 GeV) electron beam at the Linac Coherent Light Source (LCLS) at SLAC. Time‐resolved measurements of both longitudinal and transverse wakefields of the device are presented and ... [more] »

Category: CE Seminar

2016-07-11

25 Jul 2016, 16:15–17:45; Location: S4|10-314

Electrical machines commonly consist of moving and stationary parts, e.g., an electric motor features a rotor and a stator. If volume based numerical schemes such as the Finite Element Method (FEM) are applied the electromagnetic simulation of such devices is a challenging task since the variation of the geometrical configuration needs to be incorporated ... [more] »

Category: CE Seminar

2016-06-13

12 Jul 2016, 16:00–17:30; Location: S4|10-1

Measuring and reporting performance of parallel computers constitutes the basis for scientific advancement of high-performance computing (HPC). Most scientific reports show performance improvements of new techniques and are thus obliged to ensure reproducibility or at least interpretability. Our investigation of a stratified sample of 120 papers across ... [more] »

Category: CE Seminar

2016-04-07

11 Jul 2016, 16:15–17:45; Location: S2|17-103

Non-destructive testing and evaluation (NDT&E) by ultrasonic (or electromagnetic) waves is important for the identification of material parameters, for quality assurance and life-time control. Many NDT&E techniques and procedures are available, but generally rely on a considerable amount of a priori knowledge and expertise which are often expensive ... [more] »

Category: CE Seminar

2016-06-21

11 Jul 2016, 14:00–15:30; Location: S4|10-314

The MMPDE moving mesh method is a dynamic mesh adaptation method for use in the numerical solution of partial differential equations. It employs a partial differential equation (MMPDE) to move the mesh nodes continuously in time and orderly in space while adapting to evolving features in the solution of the underlying problem. The MMPDE is formulated as the ... [more] »

Category: CE Seminar

2016-02-03

7 Jul 2016, 17:00–18:30; Location: S4|10-314

The goal of an a posteriori error analysis for an approximate PDE solution is to establish the equivalence of error and a posteriori estimator. Unfortunately, this equivalence is often only up to so- called oscillation terms. In this talk we shall clarify the reasons for the presence of oscillation and point out shortcomings of common oscillation terms. ... [more] »

Category: CE Seminar

2016-06-13

1 Jul 2016, 10:00–11:30; Location: S2|17-114

ACE3P is a 3D massively parallel electromagnetic simulation suite that has been developed at SLAC National Accelerator Laboratory for the past decades. This set of codes is based on the finite-element method so that geometries of complex structures can be represented with high fidelity through conformal grids, and high solution accuracies can be obtained ... [more] »

Category: CE Seminar

2016-04-07

27 Jun 2016, 16:15–17:45; Location: S2|17-103

The project nanoCOPS is a collaborative research project within the FP7-ICT research program funded by the European Union. The consortium comprises experts in mathematics and electrical engineering from six universities (BU Wuppertal, HU Berlin, Brno UT, TU Darmstadt, FH Oberösterreich Hagenberg im Mühlkreis, EMAU Greifswald), a research institute ... [more] »

Category: CE Seminar

2016-05-30

24 Jun 2016, 10:30–12:00; Location: S2|02-C120

Even though supercomputers are typically described in terms of their floating point performance, science applications also need significant I/O performance for all parts of the science workflow. This ranges from reading input data, to writing simulation output, to conducting analysis across years of simulation data. This talk presents recent data on the use ... [more] »

Category: CE Seminar

2016-04-07

30 May 2016, 16:15–17:45; Location: S2|17-103

In the development of numerical methods to solve boundary value problems the requirement of flexible mesh handling gains more and more importance. The BEM-based finite element method [1] is one of the new promising strategies which yield conforming approximations on polygonal and polyhedral meshes, respectively. This flexibility is obtained by special ... [more] »

Category: CE Seminar

2016-04-07

9 May 2016, 16:15–17:45; Location: S2|17-103

We consider the scattering of acoustic or electromagnetic waves at a penetrable object composed of different homogeneous materials, that is, the material coefficients are supposed to be piecewise constant in sub-domains. This makes possible to recast the problem into boundary integral equations posed on the interfaces. Those can be discretized by means of ... [more] »

Category: CE Seminar

2016-04-07

2 May 2016, 16:15–17:45; Location: S2|17-103

Absorbing boundary conditions and perfectly matched layers are not only useful for the truncation of computational domains, they can also be very effectively used to obtain preconditioners. This was first realized in the context of Schwarz methods about 20 years ago, in the research group around Frederic Nataf and Laurence Halpern, and led to the class of ... [more] »

Category: CE Seminar

2016-03-10

26 Apr 2016, 17:00–18:30; Location: S4|10-1

The subsurface holds numerous resources ranging from groundwater and minerals to energy (e.g., geothermal, hydrocarbons), but it can also act as storage site for CO_{2} and nuclear waste. Any optimal and safe utilization of the deep subsurface requires a thorough ... [more] »

Category: CE Seminar

2016-04-04

21 Apr 2016, 10:30–12:00; Location: S4|10-314

Many incompressible flows of engineering interest involve fluids that are governed by complex constitutive relations. For viscoelastic fluids in particular, the advective nature of the constitutive equation requires numerical stabilization. Moreover, the use of three distinct variable fields means that two separate compatibility conditions must be ... [more] »

Category: CE Seminar

2016-04-07

19 Apr 2016, 10:00–11:30; Location: S2|17-103

Category: CE Seminar

2016-02-22

31 Mar 2016, 17:00–18:30; Location: S4|10-1

The One-shot method for design optimization problems has been successfully implemented for various physical applications. To this end, a slowly convergent primal fixed-point iteration of the underlying state equation is augmented by an adjoint iteration and a corresponding preconditioned design update. Besides a suitable choice for the ... [more] »

Category: CE Seminar

2016-01-29

25 Feb 2016, 17:00–18:30; Location: S4|10-1

Modern parallel architectures have a complex memory hierarchy, which consists of several cache levels and multiple memory controllers per system. In such architectures, the performance of memory accesses from a thread depends highly on which core the thread is executing and on which cache/memory controller the data is located. Therefore, ... [more] »

Category: CE Seminar

2016-01-08

15 Feb 2016, 16:15–17:45; Location: S2|17-103

We present an asynchronous method for the explicit integration of multiscale partial differential equations with a particular focus on microwave-plasma interactions. This method is restricted by a local CFL condition rather than the traditional global CFL condition. Moreover, contrary to other local time-stepping (LTS) methods, the asynchronous algorithm ... [more] »

Category: CE Seminar

2016-02-08

8 Feb 2016, 16:15–17:45; Location: S2|17-103

The efficient numerical solution of eddy current problems, whether formulated with differential or integral techniques, requires some topological pre-processing. Kotiuga, in his pioneering papers in the eighties, showed that computational topology is something that one should get familiar with when bumps into problems related with the design of ... [more] »

Category: CE Seminar

2015-12-08

21 Jan 2016, 17:30–19:00; Location: S4|10-1

PDE constrained optimal control problems with pointwise state constraints are known to cause certain theoretical and numerical difficulties. In this talk, we are concerned with an elliptic Dirichlet boundary control problem with low regularity of the state variable. After discussing first order optimality conditions in KKT-form, we will focus on presenting ... [more] »

Category: CE Seminar

2015-10-21

15 Dec 2015, 17:00–18:30; Location: S4|10-1

Fast chemical reactions in combustion take place in thin layers, which are usually called flamelets. The flamelet regime is the most prominent one in technical applications. Thus, flamelet-based models have been used very successfully and are actively developed for the simulation of turbulent combustion by the scientific community. ... [more] »

Category: CE Seminar

2015-11-19

27 Nov 2015, 15:30–17:00; Location: S2|17-103

Der Vortrag behandelt die schnelle numerische Lösung elliptischer Randwertprobleme mittels hierarchischer Matrizen. Im ersten Teil des Vortrags werden nicht-lokale Operatoren, die beispielsweise durch Diskretisierung von Integraloperatoren entstehen, untersucht. Die auftretenden Systemmatrizen sind vollbesetzt, so dass bereits ihre Generierung eine ... [more] »

Category: CE Seminar

2015-10-02

5 Nov 2015, 17:00–18:30; Location: S4|10-1

For efficient detailed aerodynamic or aeroacoustic designs as well as optimal active flow control, the use of adjoint approaches is an essential ingredient. Using adjoint methods, one is able to compute the gradients needed for sensitivity-based optimization and control methods, with a numerical effort independent from the number of ... [more] »

Category: CE Seminar

2015-10-22

2 Nov 2015, 16:15–17:45; Location: S2|17-103

The finite-element time-domain simulation of nonlinear systems requires the iterative solution of a large, sparse system of equations at every time-step. Model-order reduction is a powerful tool for reducing the computational effort for this task. State-of-the-art methods compute an affine approximation to the nonlinearity. In contrast, the ... [more] »

Category: CE Seminar

2015-06-19

17 Jul 2015, 14:00–15:30; Location: S4|10-1

**Abstract**
With rising system and application complexity, performance analysis is more important, but also more difficult than ever. Traditional performance are capable of measuring large volumes of performance data that can help with this process, but the interpretation of this data is becoming more and more the bottleneck. Simply comparing ... [more] »

Category: CE Seminar

2015-07-06

16 Jul 2015, 10:00–11:30; Location: S4|10-314

Traditionally in the geodynamics community, staggered grid finite difference schemes and mixed Finite Elements (FE) have been utilised to discretize the variable viscosity Stokes problem. While these methods are considered to be sufficiently robust and accurate for a wide range of variable viscosity problems they tend to have inf-sup constants which are ... [more] »

Category: CE Seminar

2015-07-09

15 Jul 2015, 14:00–15:30; Location: S4|10-1

**Abstract**
Supercomputers help to analyze huge data sets and to simulate complex theories in different science domains. Today, the results of these analyses and simulations are visualized using GPUs in workstations or small, dedicated visualization clusters. However, visualization on GPUs becomes harder and harder due to the ever increasing data size ... [more] »

Category: CE Seminar

2015-05-26

6 Jul 2015, 17:00–18:30; Location: S4|10-1

The Virtual Element Method (VEM) is a generalisation of the finite element method recently introduced by Beirao da Veiga, Brezzi, Cangiani, Manzini, Marini and Russo in 2013, which takes inspiration from modern mimetic finite difference schemes, and allows to use very general polygonal/polyhedral meshes. This talk is concerned with a new method based ... [more] »

Category: CE Seminar

2015-03-23

24 Jun 2015, 17:00–18:30; Location: S4|10-314

In this talk we will give an overview of the High Performance Scientific Computing activities that are currently taking place at the Computer Science and Engineering of the University Politehnica of Bucharest, Romania. In particular, we will present applications from the areas of: meteorology, aerospace, ... [more] »

Category: CE Seminar

2015-06-22

23 Jun 2015, 13:00–14:30; Location: L1|01-K328

In this talk we will present efficient numerical schemes for two classes of complex flows: i) Fluid-Structure interaction problems with application in hemodynamics and ii) Singular limit flows with application in meteorology. We derive problem-suited finite volume and/or Discontinous Galerkin approximations and analyse the scheme with respect to ... [more] »

Category: CE Seminar

2015-03-23

15 Jun 2015, 17:00–18:30; Location: S4|10-314

In this talk we discuss the current design and implementation of ADiJaC, an automatic differentiation tool for Java classfiles. ADiJaC uses source code transformation to generate derivative codes in both the forward and the reverse modes of automatic differentiation. We describe the overall architecture of the tool, and ... [more] »

Category: CE Seminar

2015-04-15

2 Jun 2015, 17:00–18:30; Location: S4|10-1

After a brief introduction to the boundary element method and H-matrices we consider the efficient solution of strongly elliptic potential problems with stochastic Dirichlet data. The computation of the solution’s two-point correlation is well understood if the two-point correlation of the Dirichlet data is known and sufficiently smooth. Unfortunately, the ... [more] »

Category: CE Seminar

2015-03-27

23 Apr 2015, 16:00–17:30; Location: S4|10-314

We consider Allen-Cahn and Cahn-Hilliard equations as phase field models with constant and variable mobility. Both equations are discretized in space using symmetric interior penalty discontinuous Galerkin (SIPG) finite elements. Time discretization is performed by the energy stable average vector field (AVF) method for gradient systems like Allen-Cahn ... [more] »

Category: CE Seminar

2015-02-09

9 Mar 2015, 17:00–18:30; Location: S4|10-1

The boundary element method is a widely used technique for solving problems governed by elliptic PDEs. On the other hand, the application of integral equation methods to time dependent problems is much less developed and a topic of current research. Time dependence is reflected in the fact that boundary integral operators involve integrals over time in ... [more] »

Category: CE Seminar

2015-01-27

9 Feb 2015, 16:15–17:45; Location: S2|17-103

Two important influences on the accuracy of simulation results are the approximation properties of the numerical scheme with respect to, on the one hand, the unknown solution, and on the other hand, the geometry representation. The latter aspect poses a particular challenge in the context of deforming computational domains. These deformations can either be ... [more] »

Category: CE Seminar

2014-12-15

12 Jan 2015, 16:15–17:45; Location: S2|17-103

In this talk we give an overview of the FHO activities in the fp-7 research projects ICESTARS, nanoCOPS, the ENIAC project ARTEMOS, and the Austrian basic research project "Spline/wavelet based methods in circuit simulation". In Radio Frequency (RF) circuits one observes slowly varying envelope or baseband signals modulated by a carrier signal at ... [more] »

Category: CE Seminar

2014-11-27

2 Dec 2014, 14:30–15:30; Location: S3|06-257

High dimensional data exhibit distinct properties compared to its low dimensional counterpart; this causes a common performance decrease and a formidable computational cost increase of traditional approaches. Novel methodologies are therefore needed to characterize data in high dimensional spaces. Considering the parsimonious degrees of freedom of ... [more] »

Category: CE Seminar

2014-10-16

2 Dec 2014, 14:00–15:30; Location: S4|10-414

Physical phenomena in most engineering fields and applications are inherently nonlinear. Yet, most established engineering design tools have been developed for idealised linear systems. In particular, structural nonlinearity in engineering design has been traditionally associated with problems and loss of functionality, often at the expense of overdesign ... [more] »

Category: CE Seminar

2014-10-02

1 Dec 2014, 16:15–17:45; Location: S2|17-103

Electrostatic discharge (ESD) is a serious design concern in microelectronic device fabrication and usage. Current spikes of the order of amperes active over a time lap of a nanosec need to be screened off from the core circuits by ESD protection devices. On-chip silicon controlled rectifiers are used for this purpose. The fast transient effect lead to ... [more] »

Category: CE Seminar

2014-09-12

30 Oct 2014, 17:00–18:30; Location: S4|10-1

The powerful properties of formulations enriched with discontinuous or singular functions like XFEM, GFEM and SDA is the ability to represent features independently of the mesh structure. However, a problematic point in their practical implementation is given by the quadrature to compute the element stiffness. In fact, especially in 3D, the element are ... [more] »

Category: CE Seminar

2014-06-23

28 Oct 2014, 17:00–18:30; Location: S4|10-1

Derivatives of mathematical functions are needed in various areas of computational engineering. Examples include the solution of nonlinear systems of equations and inverse problems. When the function is given in the form of a computer program, automatic differentiation (AD) enters the picture. In this set of powerful techniques, ... [more] »

Category: CE Seminar

2014-07-29

25 Sep 2014, 16:30–18:00; Location: S4|10-1

Simulations of realistic Earth science problems are characterised by massive scale and coupled sets of equations. In the case of problems such as subduction zones, geometric effects are central. These features demand numerical methods and software libraries that are flexible and high performance, and the deployment of scalable linear solvers. In working ... [more] »

Category: CE Seminar

2014-08-15

1 Sep 2014, 16:15–18:00; Location: S4|10-1

We consider parameterized mathematical programs with constraints governed by the generalized nonlinear complementarity problem and with additional non-equilibrial constraints. We study a local behavior of stationarity maps that assign the respective C- or M-stationarity points of the problem to the parameter. We provide criteria for the isolated calmness ... [more] »

Category: CE Seminar

2014-04-29

28 Jul 2014, 16:15–17:45; Location: S2|17-103

In this presentation we will address different aspects concerning Reduced Basis (RB) methods for parametric partial differential equations (PDEs). This class of model reduction techniques enables rapid solution of parametric problems in the real-time or many-query context and has gained quite some interest and wide development over the last decade After ... [more] »

Category: CE Seminar

2014-04-29

21 Jul 2014, 16:15–17:45; Location: S2|17-103

We introduce a relativistic splitting structure as a means to map fields and equations of electromagnetism from curved four-dimensional spacetime to three-dimensional observer's space. We focus on a minimal set of mathematical structures that are directly motivated by the language of the physical theory. Space-time, world-lines, time translation, space ... [more] »

Category: CE Seminar

2014-06-23

16 Jul 2014, 17:00–18:30; Location: S4|10-314

For numerous applications the exploitation of structure and/or parallelism is indispensable for the efficient computation of derivatives and also for the design of new solution approaches. We discuss recent developments integrated in the software package ADOL-C for the algorithmic differentiation of C and C++ codes to utilize ... [more] »

Category: CE Seminar

2014-04-29

14 Jul 2014, 16:15–17:45; Location: S2|17-103

Category: CE Seminar

2014-04-29

7 Jul 2014, 16:15–17:45; Location: S2|17-103

Particle accelerators are among the most complicated contemporary devices and consist of a large number of components, each with a specific function. All components need to be tuned with respect to each other to achieve the prescribed particle beam characteristics. Seemingly small deviations from an individual component's design specifications may induce ... [more] »

Category: CE Seminar

2014-06-30

4 Jul 2014, 11:00–12:30; Location: S4|10-314

In mathematical physics and engineering, Trefftz approximations by definition involve functions that satisfy the underlying differential equation of the problem (as well as the interface boundary conditions). Examples include harmonic polynomials for the Laplace equation; plane waves, cylindrical or spherical harmonics for wave problems; exponential ... [more] »

Category: CE Seminar

2014-05-09

3 Jul 2014, 17:00–18:30; Location: S4|10-1

An optimal control problem governed by an elliptic variational inequality is considered. We focus on the optimal control of the obstacle problem, which is a prototypical example of variational inequalities of the first kind. A robust multigrid strategy for solving obstacle problems will be presented. This algorithm is then extended in order to apply ... [more] »

Category: CE Seminar

2014-06-04

26 Jun 2014, 16:30–18:00; Location: S4|10-1

Simulation of flow and transport processes in porous media provides a formidable challenge and application field for high-performance computing. Relevant continuum-scale models include partial differential equations of elliptic, parabolic and hyperbolic type which are coupled through highly nonlinear coefficient functions. The multi-scale character and ... [more] »

Category: CE Seminar

2014-02-06

22 May 2014, 15:30–17:00; Location: S4|10-314

In industrial product development, design decisions are mostly based on intensive parameter studies combined with expert knowledge, where in case of complex technical systems like aero engines typically several experts from different departments have to be involved. However, typically each department uses its own analysis programs with its own data ... [more] »

Category: CE Seminar

2014-05-09

20 May 2014, 17:00–18:30; Location: S4|10-1

Wavy plies or wrinkles in carbon fiber reinforced plastic (CFRP) composite structures can result in performance knockdowns. The performance impact of the ply distortion can depend on many factors, but two commonly desired parameters are the wrinkle height and width. An ultrasonic B-scan of the wrinkle can reveal the ply distortion; however, visual ... [more] »

Category: CE Seminar

2014-04-29

19 May 2014, 10:00–11:30; Location: S4|10-1

Category: CE Seminar

2014-04-24

28 Apr 2014, 17:00–18:30; Location: S4|10-1

The coupling and finite and boundary element methods has been attractive for the numerical solution of boundary value problems of second order partial differential equations for decades. In particular, so-called non-symmetric formulations have been very popular in applications for a long time. Originally, the results on the stability of related ... [more] »

Category: CE Seminar

2014-02-21

28 Apr 2014, 16:15; Location: S2|17/103, Schlossgartenstrasse 8

Magnetostrictive materials belong to the large class of Smart Materials, which change their mechanical behavior and properties in response to the application of an external field, such as temperatur or magnetic field. Particularly magnetostrictive elastomers, composites consisting of ferrous particles dispersed in an elastomeric matrix, can exhibit large ... [more] »

Category: CE Seminar

2014-04-24

28 Apr 2014, 15:30–17:00; Location: S4|10-1

This talk will focus on issues arising in the context of the generation of a discrete adjoint version of OpenFOAM using algorithmic differentiation (AD). The existing discrete adjoint version of OpenFOAM is based on our AD tool dco/c++ (derivate code by overloading in C++). It uses the adjoint MPI (AMPI) library for adjoint message passing. Prototyped at ... [more] »

Category: CE Seminar

2014-02-04

22 Apr 2014, 15:45–17:15; Location: S4|10-1

In this talk he will discuss the source analysis tool PBound, that estimates the upper performance bounds of C and Fortran applications. Built on the ROSE compiler framework, PBound generates parametrized expressions for different types of memory accesses and integer and floating-point computations. Additionally, PBound uses application reuse distance ... [more] »

Category: CE Seminar

2014-01-17

17 Feb 2014, 16:15–17:00; Location: S2|17-103

Deep brain stimulation (DBS) has evolved as a widely employed procedure to treat the symptoms of motor skill disorders such as Parkinson’s disease, essential tremor and dystonia. Although successfully employed across various clinical fields, the fundamental mechanisms of action of DBS remain uncertain. Starting in the last decade, many computational models ... [more] »

Category: CE Seminar

2014-01-20

6 Feb 2014, 17:00–18:30; Location: S4|10-1

Computing discrete adjoints by algorithmic differentiation (AD) enables gradient-based optimization for high-dimensional problems. First, I introduce AD principles and implementation options (i.e. operator overloading) relevant to models written in C++ and parallelized with MPI. Then I present our ongoing work with the Ice Sheet System Model (ISSM), ... [more] »

Category: CE Seminar

2013-09-20

27 Jan 2014, 16:15–17:45; Location: S2|17-103

In electrical engineering, the input data (dimensions, material properties, external inputs, etc.) of models are often assumed to be known exactly. The models as well as their outputs are then deterministic. However, in the real world, the input data are often stochastic. The dimensions of any device are known within a given uncertainty (tolerance) due to ... [more] »

Category: CE Seminar

2013-09-20

13 Jan 2014, 16:15–17:45; Location: S2|17-103

Simulation of micro-turbulence in magnetic fusion plasmas either in stellarators or in tokamaks can be realised efficiently with Particle In Cell methods (PIC) provided some efficient noise reduction is achieved so that noise levels are well below signal levels. This can be achieved using a control variate method using a stochastic process associated with ... [more] »

Category: CE Seminar

2013-12-12

17 Dec 2013, 11:00–12:30; Location: S4|10-1

We consider a PDE constrained optimization problem governed by a free boundary problem. The state system is based on coupling the Laplace equation in the bulk with a Young-Laplace equation on the free boundary to account for surface tension, as proposed by P. Saavedra and L.R. Scott. This amounts to solving a second order system both in the bulk and on the ... [more] »

Category: CE Seminar

2013-11-26

3 Dec 2013, 10:00–11:30; Location: S4|10-1

Many parallel applications suffer from latent performance limitations that may prevent them from scaling to larger machine sizes. Often, such scalability bugs manifest themselves only when an attempt to scale the code is actually being made - a point where remediation can be difficult. However, creating analytical performance models that would allow such ... [more] »

Category: CE Seminar

2013-11-26

2 Dec 2013, 14:00–15:30; Location: S4|10-1

In today's economic climate, time to market, or more generally time to solution, is critical. At the same time, mainstream hardware does not only become massively parallel, it also becomes much more diverse: Graphics Processors (GPUs), large vector machines such as Intel's Xeon-Phi, and even programmable hardware in the form of FPGAs find an increasing ... [more] »

Category: CE Seminar

2013-11-26

2 Dec 2013, 10:00–11:30; Location: S4|10-1

Parallel Programming has long closely been tied to high performance computing. Today's ubiquity of multi-core chip architectures radically changes this: parallel programming moves from a niche market into the main stream of computing. At the same time, hardware becomes more and more diverse: varying numbers of cores with complex cache hierarchies, ... [more] »

Category: CE Seminar

2013-09-20

18 Nov 2013, 16:15–17:45; Location: S2|17-103

Category: CE Seminar

2013-11-06

13 Nov 2013, 16:30–18:00; Location: S4|10-1

“More bang for the buck” is the promise of deploying accelerators attached to commodity host processors for technical computing. Since NVIDIA introduced the CUDA programming model in 2006, more and more programmers started using graphics processors for technical computing. Amazing success stories reported high speed-up rates of applications accelerated by ... [more] »

Category: CE Seminar

2013-09-20

4 Nov 2013, 16:15–17:45; Location: S2|17-103

The concept of Isogeometric Analysis (IGA) was introduced by Hughes with the aim of bridging the gap between computer aided design (CAD) and the finite element method. This aim is pursued by adopting the same Non Uniform Rational B-Spline (NURBS) basis functions to construct both trial and test spaces in the discrete variational formulation of differential ... [more] »

Category: CE Seminar

2013-10-29

1 Nov 2013, 13:00–14:30; Location: S4|10-1

Pushing back the frontiers of simulation technology in science and engineering becomes ever more complex. Better simulations of more realistic systems require greater complexity in both equations and numerics, while the shift from increasing processor speed to massive fine-scale parallelism radically increases the complexity of the software implementation. ... [more] »

Category: CE Seminar

2013-10-04

24 Oct 2013, 17:00–18:30; Location: S4|10-1

Understanding the properties and consequences of friction under light normal loads is fundamental to further advancing areas such as tactile sensing, haptic systems used in robotic gripping of sensitive objects, and characterization of products that range from the softness of fabrics to effects of surfactants, such as lotions, on skin. In tactile sensing, ... [more] »

Category: CE Seminar

2013-09-30

22 Oct 2013, 17:00–18:30; Location: S4|10-1

An analytical-numerical model based on first principles for representation of the motions of a submarine in the horizontal and in the vertical plane is presented. The model is implemented through computational algebra, being its parameters expressed as function of the main dimensions and form coefficients of the hull and its appendices, ... [more] »

Category: CE Seminar

2013-09-20

21 Oct 2013, 16:15–17:45; Location: S2|17-103

The sustainable environmental tendencies lead to a highly optimized design of majority of consumer products. In Materials Engineering, this is mirrored by a race towards miniaturization and top product performance. A potential success is seen in a detailed understanding and incorporation of characteristic physical processes taking place at materials ... [more] »

Category: CE Seminar

2013-09-18

30 Sep 2013, 17:00–18:30; Location: S4|10-1

We describe our efforts in performance modeling in the context of automatic performance tuning. We consider analytic models constructed through source code analysis, semi-analytic models constructed with a combination of source code analysis and empirical measurement, and fully empirical models. We describe several uses ... [more] »

Category: CE Seminar

2013-08-29

26 Sep 2013, 17:00–18:30; Location: S4|10-1

In this talk we show a new approach to the numerical simulation of Bingham fluids, based on semismooth Newton methods. From pipe flow to thermally convective flow, we present the challenges and the modeling and numerical tools to overcome such issues. [more] »

Category: CE Seminar

2013-06-03

17 Sep 2013, 17:00–18:30; Location: S4|10-1

The past, present and future scalability of the Uintah Software framework is considered with the intention of describing a successful approach to large scale parallelism. Uintah allows the solution of large scale fluid-structure interaction problems through the use of fluid flow solvers coupled with particle-finite element based solid methods. In addition ... [more] »

Category: CE Seminar

2013-07-02

18 Jul 2013, 17:00–18:30; Location: S4|10-1

In this work, we present a computationally efficient finite element (FE) model for statics, dynamics and vibration control of smart composite and sandwich shallow shells integrated with piezoelectric sensors and actuators, considering their nonlinear characteristics under strong electric field. The nonlinearity is modeled using the rotationally invariant ... [more] »

Category: CE Seminar

2013-07-08

10 Jul 2013, 14:00–15:30; Location: S3|05-074

In this talk, I will present our recent work on robustly tracking objects that deform due to an external applied force. The geometry of the object is reconstructed over time based on noisy observations from a single viewpoint. A template mesh of the object in its rest-state is fit to observations in a nonlinear optimization. We use a redundant ... [more] »

Category: CE Seminar

2013-02-14

9 Jul 2013, 17:00–18:30; Location: S4|10-1

Hybrid parallel programming with the message passing interface (MPI) for internode communication in conjunction with a shared-memory programming model to manage intranode parallelism has become a dominant approach to scalable parallel programming. While this model provides a great deal of flexibility and performance potential, it saddles programmers with ... [more] »

Category: CE Seminar

2013-06-03

4 Jul 2013, 17:00–18:30; Location: S4|10-1

Penalization approaches are nowadays commonly employed to solve boundary or initial-boundary value problems. They consist in embedding the original, possibly complex spatial domain inside a bigger domain having a simpler geometry, for example a torus, while keeping the boundary conditions approximately enforced thanks to new terms that are added to the ... [more] »

Category: CE Seminar

2013-04-30

25 Jun 2013, 17:00–18:30; Location: S4|10-1

The simulation of turbulent flows by the Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) approaches requires extremely low numerical dispersion and dissipation. Finite Element-like high-order methods such as the discontinuous Galerkin (DGM), spectral difference (SDM) and spectral element methods (SEM), ... have attracted considerable ... [more] »

Category: CE Seminar

2013-06-19

21 Jun 2013, 10:00–11:30; Location: S3|06-257

In this seminar, we will discuss a number of recent advances in visual pattern recognition and image classification. In particular, we will present three applications of visual pattern recognition: to emotion recognition, 3-D vision for assistive navigation, and human activity monitoring using Doppler radar. One of the challenges of visual pattern ... [more] »

Category: CE Seminar

2013-04-19

20 Jun 2013, 17:00–18:30; Location: S4|10-1

Many engineering problems such as chemical reaction processes, population dynamics, ground water contamination are governed by coupled diffusion-convection-reaction partial differential equations (PDEs) with nonlinear source or sink terms. Nonlinear transport systems are typically convection and/or reaction dominated with characteristic solutions possessing ... [more] »

Category: CE Seminar

2013-02-12

19 Jun 2013, 17:15–18:45; Location: S4|10-1

This talk is provided together with the department of mathematics. [more] »

Category: CE Seminar

2013-06-07

17 Jun 2013, 10:30–12:00; Location: S2|17-103

Shielding sheets are commonly used in the protection of electronic devices. With their large aspect ratios they become a serious issue for the direct application of the finite element method, as many small cells are required to resolve the sheets, as well as the direct application of the boundary element method (BEM) due to the occuring almost singular ... [more] »

Category: CE Seminar

2013-03-21

29 May 2013, 17:15–18:45; Location: S2|14-24

Compressed Sensing is a novel research area, which was introduced in 2006, and since then has already become a key concept in various areas of applied mathematics. It predicts that high-dimensional signals, which allow a sparse representation by a suitable basis/frame, can be recovered from highly incomplete linear measurements by using efficient ... [more] »

Category: CE Seminar

2013-05-21

27 May 2013, 16:15–17:45; Location: S2|17-103

A broad class of structures in electronics and high-frequency engineering exhibits linear time-invariant system properties. It ranges from antennas and filters through wiring structures of integrated circuits to the cavities of linear accelerators and the elementary cells of meta-materials. Such structures constitute distributed-parameter systems of high ... [more] »

Category: CE Seminar

2013-02-21

23 May 2013, 17:00–18:30; Location: S4|10-1

The multicore trend has brought forth a variety of computer architectures suitable for numerical simulation. Nowadays there is no longer a single driving force for numerical performance. To make efficient use of the hardware the programmer must address multiple architectural features at the same time – otherwise he will face a performance ... [more] »

Category: CE Seminar

2013-03-13

14 May 2013, 17:00–18:30; Location: S4|10-1

First, an overview about the research done at the institute will be given to set the framework why we are interested in the computationally so demanding particle methods. These methods have recently emerged as engineering tools that can be widely used in many different disciplines. Due to their meshless nature, they are especially well suited for problems ... [more] »

Category: CE Seminar

2013-04-08

15 Apr 2013, 16:15–17:45; Location: S2|17-103

National power grids are currently evolving from static entities, producing mainly a uni-directional ﬂow from generation to loads, to more dynamic and decentralized structures. These emerging power systems should accommodate the local generation by renewable sources and peak demands of electrical vehicle charging. The cross-border interconnection of power ... [more] »

Category: CE Seminar

2012-12-17

4 Apr 2013, 17:00; Location: S4|10-1

Suppression of brake squeal has received a lot of attention by engineering researchers in the past. It is widely accepted in the scientific community that the self-excited vibrations induced by the frictional contact between brake disc and brake pad are the main cause of brake squeal. Presently, a variety of methods are being discussed to avoid squealing, ... [more] »

Category: CE Seminar

2012-11-19

7 Feb 2013, 17:00; Location: S4|10-1

We study the fluid-structure interaction encountered in hydraulic fracturing, a technique used by the oil and gas industry. Simulating this process needs to take into account the interaction between a fracturing solid and the fluid flow in the crack. In particular, with the possible presence of a fluid lag, the evolving fluid front inside the crack and the ... [more] »

Category: CE Seminar

2012-11-09

6 Dec 2012, 17:00; Location: S4|10-1

This talk is concerned with the derivation of computable and guaranteed upper and lower bounds of the dierence between the exact and the approximate solution of boundary value problems for static Maxwell type equations. Our analysis is based upon purely functional argumentation and does not attract specic properties of an approximation method. Therefore, ... [more] »

Category: CE Seminar

2012-11-09

22 Nov 2012, 17:00; Location: S4|10-1

Multi-domain and multi-physics problems with moving interfaces and parameter studies with changing geometric domains can be severely limited by the use of conforming meshes when complex geometries in three spatial dimensions are involved. To overcome these limitations, several fixed-grid methods based on XFEM, Nitsche's method and related approaches have ... [more] »

Category: CE Seminar

2012-11-01

8 Nov 2012, 17:00; Location: S4|10-1

Software development in academia is subject to a set of special circumstances that make the development of sustainable, maintainable, and high-quality software particularly difficult. In this talk I address these problems, explain why academia might be facing substantials problems in years to come, but also why the creation of ... [more] »

Category: CE Seminar

2012-08-28

11 Oct 2012, 17:00; Location: S4|10-1

Consistently replacing prototypes or physical experiments by computations has been pursued within the Engineering and Applied Science community in the last decades, to a large extent due to the impressive computer power available nowadays. But the use of computer simulations as an effective tool still faces conceptual and technical challenges. Chief among ... [more] »

Category: CE Seminar

2012-07-23

20 Sep 2012, 17:00; Location: S4|10-1

A three-dimensional nonlinear time-marching method and numerical analysis for aeroelastic behaviour of oscillating blade row has been presented. The approach is based on the solution of the coupled fluid-structure problem in which the aerodynamic and structural equations are integrated simultaneously in time. Thus providing the correct formulation of ... [more] »

Category: CE Seminar

2012-08-06

9 Aug 2012, 10:00; Location: S4|10-1

Category: CE Seminar

2012-05-29

4 Jul 2012, 17:00; Location: S4|10-1

The multicore era has led to a renaissance for shared memory parallel programming models. Moreover, the introduction of Task-level parallelization raises the level of abstraction compared to thread-centric expression of parallelism. However, shared memory parallel applications may exhibit poor performance on NUMA systems if ... [more] »

Category: CE Seminar

2012-05-29

2 Jul 2012, 14:00; Location: S4|10-1

We will discuss recent advances in the Portable, Extensible Toolkit for Scientific computing (PETSc) that enable application scientists to develop composable linear, nonlinear, and timestepping solvers for multiphysics and multilevel methods on emerging extreme-scale architectures. Examples of usage include lithosphere dynamics, ... [more] »

Category: CE Seminar

2012-05-29

6 Jun 2012, 17:00; Location: S4|10-1

We describe recent and ongoing work in the area of automatic performance tuning. By employing specialization, we can develop tuned variants for the most common usage scenarios in a given application. By posing the empirical search problem as a mathematical optimization problem, we can draw upon the large body of research in derivative free optimization ... [more] »

Category: CE Seminar

2012-03-09

31 May 2012, 17:00; Location: S4|10-1

At GSI a new data center is being built, which sets new standards in energy efficiency and cost. The computer racks are cooled directly with heat exchangers and mounted on a steel structure much like a high rack warehouse. This architecture enables power densities exceeding 20 kW/m² and floor or 100 kW/m². The entire data center will support computers up to ... [more] »

Category: CE Seminar

2012-05-08

14 May 2012, 09:00; Location: S2|17-114

Substrate integrated waveguide (SIW) technology has been largely explored as a low-cost low-profile transmission line in passive microwave and millimeter circuits and devices. Yet,little research has been done to assess SIW performance in integration with active elements, e.g. Power Amplifier (PA) and Low Noise Amplifier (LNA). The ... [more] »

Category: CE Seminar

2012-01-19

3 May 2012, 17:00; Location: S4|10-1

In many engineering applications, the way natural fluid flows behave leaves some room for improvement. While geometric optimizations, such as streamlined shapes, require no additional energy input, they might not always be possible, feasible, or sufficient.

Another option is active flow control, where a suitable actuator more or less ... [more] »

Category: CE Seminar

2012-03-22

17 Apr 2012, 17:00; Location: S4|10-1

The FLAME project has yielded modern alternatives to LAPACK and related efforts. An attractive feature of this work is the complete vertical integration of the entire software stack, starting with low level kernels that support the BLAS and finishing with a new distributed memory library, Elemental. In between are layers that target a single core, ... [more] »

Category: CE Seminar

2012-01-13

8 Mar 2012, 17:00; Location: S4|10-1

Nowadays, a variety of modeling strategies exist for the computer simulation of electromagnetic wave propagation in the time domain. Despite a lot of advances on numerical methods able to deal accurately and in a flexible way with complex geometries through the use of unstructured (non-uniform) discretization meshes, the FDTD (Finite Difference Time Domain) ... [more] »

Category: CE Seminar

2012-01-20

3 Feb 2012, 17:15; Location: S2|14-024

Proteins are biological nanomachines. Virtually every function in the cell is carried out by proteins - ranging from protein synthesis, ATP synthesis, molecular binding and recognition, selective transport, sensor functions, mechanical stability, and many more. The combined interdisciplinary efforts of the past years have revealed how many of these ... [more] »

Category: CE Seminar

2011-10-12

1 Nov 2011, 15:30; Location: S4|10-142

Category: CE Seminar

2011-10-09

31 Oct 2011, 15:30; Location: S4|10-142

Category: CE Seminar

2011-10-14

27 Oct 2011, 08:30; Location: S4|10-142

Category: CE Seminar

2011-10-07

26 Oct 2011, 08:30; Location: S4|10-142

Category: CE Seminar

2011-10-07

18 Oct 2011, 14:00; Location: S2|15-51

In the first part of the talk, and in order to set the stage, we will offer a multi-scale and averaging strategy to compute the solution of a singularly perturbed system when the fast dynamics oscillates rapidly; namely, the fast dynamics forms cycle-like limits which advance along with the slow dy- namics. We describe the limit as a Young measure with ... [more] »

Category: CE Seminar

2011-07-04

11 Jul 2011, 14:00; Location: S2|17-103

Trotz zunehmend komplexer werdender elektromagnetischer Probleme machen heute neue Rechnerarchitekturen die numerische Simulation großer gekoppelter Probleme möglich. Die einzelnen Teilprobleme sind oft differential-algebraische Gleichungen, die aus der Ortsdiskretisierung partieller Differentialgleichungen (PDGLn) stammen. In diesem Vortrag werden ... [more] »

Category: CE Seminar

2011-07-01

7 Jul 2011, 14:00; Location: S2|17-114

Die Diskretisierung linearer zeitinvarianter Systeme mittels finiter Elemente (FE) führt auf große, dünnbesetzte lineare Gleichungssysteme, deren Dimension typischerweise in der Größenordnung von Hunderttausend bis einigen Millionen liegt. Während ihre Lösung für eine einzelne Frequenz beim heutigen Stand der Technik kein Problem mehr bereitet, stellt die ... [more] »

Category: CE Seminar

2010-11-10

30 Jun 2011, 17:00; Location: S4|10-1

Category: CE Seminar

2011-06-14

21 Jun 2011, 14:00; Location: S2|17-114

This talk is about the advancement of grid-based simulation algorithms for modelling electromagnetic wave propagation in photonics. For this purpose, existing algorithms for problems arising from the microwave range are extended for the analysis and the design of linear passive nanostructures at optical frequencies. The focus is put on the calculation of ... [more] »

Category: CE Seminar

2011-06-14

20 Jun 2011, 14:00; Location: S2|17-103

Elektromagnetische Felder, die durch die zu beschleunigenden Ladungsträger im Teilchenbeschleuniger hinterlassen werden, stellen eine wesentliche Limitierung für im Bau befindliche und zukünftige Teilbeschleunigerprojekte dar. Zur Dämpfung dieser als Wakefelder bezeichneten elektromagnetischen Felder werden spezielle Kopplerstrukturen eingesetzt, die den ... [more] »

Category: CE Seminar

2011-05-26

16 Jun 2011, 17:00; Location: S4|10-1

Several examples of a curious interplay between analytical and numerical methods will be presented. First, accurate local (semi-)analytical Trefftz approximations lead to high-order difference schemes and to singularity-free boundary-difference methods. Second, Whitney-like interpolation, well established in finite element analysis, is now put to a new use ... [more] »

Category: CE Seminar

2010-12-17

12 May 2011, 17:00; Location: S4|10-1

This talk will discuss the recently introduced class of isogeometric finite elements, which generalize the isoparametric concept to B-splines and NURBS (Non-Uniform Rational B-Splines). The latter are one of the standard descriptions for free form surfaces and various typical engineering shapes in Computer Aided Design (CAD) software. Besides explaining the ... [more] »

Category: CE Seminar

2011-04-18

28 Apr 2011, 17:00; Location: S4|10-1

The influence of walls on the Lagrangian transport and mixing of passive scalars in turbulent two-dimensional flows is investigated. Two distinct geometries are considered by means of direct numerical simulation: a biperiodic domain and a circular domain with no-slip boundary conditions for velocity and zero flux for the scalar. A penalization method allows ... [more] »

Category: CE Seminar

2010-11-29

17 Feb 2011, 16:00; Location: S4|10-1

Flows with interfaces exhibit interactions on a large range of scales, resulting in large demands on compute power for simulations. Single-phase flows already can exhibit a large range of strongly coupled scales whose efficient computational modeling poses a challenge by itself. Immersed interfaces add small-scale transport phenomena and can dominate the ... [more] »

Category: CE Seminar

2010-09-30

10 Feb 2011, 17:00; Location: S4|10-1

We describe computations performed using the Gerris code, an open-source software implementing finite volume solvers on an octree adaptive grid together with a piecewise linear volume of fluid interface tracking method. The parallelisation of Gerris is achieved by domain decomposition into a large number of grains (a "forest of tree" approach) ... [more] »

Category: CE Seminar

2010-11-04

3 Feb 2011, 17:00; Location: S4|10-1

Category: CE Seminar

2011-01-13

2 Feb 2011, 17:15; Location: S2|14-24

Bei der Lösung von Optimierungsaufgaben bei partiellen Differentialgleichungen und von Parameteridentifikationsaufgaben werden häufig sehr ähnlich mathematische Probleme untersucht. Dabei haben die mathematischen Gebiete Inverse Probleme und Optimale Steuerung sehr unterschiedliche Herangehensweisen. Ausgehend von der Korrektheitsdefinition von Hadamard ... [more] »

Category: CE Seminar

2011-01-13

26 Jan 2011, 17:15; Location: S2|14-24

Adaptive Finite Elemente Verfahren werden seit den 1970er Jahren erfolgreich zur effizienten numerischen Lösung partieller Differenzialgleichungen verwendet. Das übliche adaptive Verfahren ist eine Iteration der Form SOLVE → ESTIMATE → MARK → REFINE. Die meisten Arbeiten zu adaptiven Finiten Elementen befassen sich mit dem Modul ESTIMATE, ... [more] »

Category: CE Seminar

2010-12-01

6 Dec 2010, 17:00; Location: S4|10-1

In this talk, we consider a state--constrained optimal control problem of Maxwell's equations based on a 'vector potential ansatz' for the control. The pointwise state constraints here play an important role to prevent singularities or to achieve certain $L^p$--regularity of the optimal state. Due to the lack of regularity of the control--to--state ... [more] »

Category: CE Seminar

2010-11-26

3 Dec 2010, 10:00; Location: S3|06-235

Category: CE Seminar

2010-10-06

16 Nov 2010, 13:30; Location: Darmstadtium, SIMPAR Conference

Robotics is rapidly expanding into the human environment and vigorously staying engaged in its emerging challenges. From a largely dominant industrial focus, robotics has undergone, by the turn of the new millennium, a major transformation in scope and dimensions. This expansion has been brought about by the maturity of the field and the advances in its ... [more] »

Category: CE Seminar

2010-11-03

11 Nov 2010, 17:00; Location: S4|10-1

Multicomponent AM-FM models, also known as McAulay-Quatieri models in audio and speech processing, are highly parametric representations of non stationary signals that are able to effectively represent a large class of real phenomena with no limitations in terms of signal kind, applicative domain, and so on. During recent decades, the elegant formulation of ... [more] »

Category: CE Seminar

2010-09-28

28 Oct 2010, 17:00; Location: S4|10-1

Since 2004, the driving behavior of more than five hundred drivers has been collected while subjects drove in real traffic, by researchers at Nagoya University in Japan. The main purpose of this data collection is to build corpora (large bodies of representative data) for a new research challenge - human behavior signal processing. Environmental and ... [more] »

Category: CE Seminar

2010-04-29

23 Sep 2010, 17:00; Location: S4|10-1

Category: CE Seminar

2010-04-29

21 Sep 2010, 15:00; Location: L1|08-4 and 23

This talk is provided together with the Center of Smart Interfaces (CSI). [more] »

Category: CE Seminar

2010-07-22

13 Sep 2010, 11:30; Location: S4|10-1

Driven by the impressive growth of the communication industry, we see a rapid convergence of digital computing and analog wireless technology. This has become possible due to the progress of, semiconductor technology into the nanometer regime which is going to continue for the next ten to fifteen years. High-level integration with unprecedented ... [more] »

Category: CE Seminar

2010-06-30

26 Aug 2010, 17:00; Location: S2|14-024

Category: CE Seminar

2010-06-11

22 Jul 2010, 17:00; Location: S4|10-1

In this presentation I will briefly introduce my research group and its goals. I will explain why we are interested in adaptive finite element methods based on computational, as opposed to mathematical/analytical error estimates. Main principles of adaptive higher-order finite elementi methods (hp-FEM) will be explained and demonstrated via live ... [more] »

Category: CE Seminar

2010-04-28

8 Jul 2010, 17:00; Location: S4|10-1

When building a mathematical model to describe the behavior of a physical system, one has often to face a certain level of uncertainty in the proper characterization of the model parameters and input data. An example is given by the study of groundwater flow, where the subsurface permeability is largely unknown and often reconstructed from few available ... [more] »

Category: CE Seminar

2010-05-06

1 Jul 2010, 17:00; Location: S4|10-1

One of the challenges of visual pattern recognition is robustness to photometric and geometric distortions that occur in uncontrolled natural environments. To this end, we have proposed recently a new paradigm for visual pattern recognition which combines feature extraction and classification in one hierarchical image classification architecture. The ... [more] »

Category: CE Seminar

2010-03-24

15 Jun 2010, 17:00; Location: S4|10-1

Traditional finite-difference methods are typically based on Taylor expansions of the differential operator. The generalized finite-difference calculus of Flexible Local Approximation MEthods (FLAME) often dramatically improves the accuracy by replacing these Taylor expansions with Trefftz functions – local solutions of the underlying differential ... [more] »

Category: CE Seminar

2010-04-21

4 Jun 2010, 13:00; Location: L1|08-4 and 23

This talk is provided together with the Center of Smart Interfaces (CSI). [more] »

Category: CE Seminar

2010-05-05

21 May 2010, 10:30; Location: S3|06-249

Es wird eine kurze Übersicht über die DFG-Projekte im DFG Schwerpunktprogramm SPP 1395 (InKoMBio) gegeben. Nach einer kurzen Einführung in die elementaren informationstheoretischen Begriffe wird auf die Analyse binärer polynomialer Systeme mittels der Fourier Analyse eingegangen. (Vorstellung des DFG-Projektes: Die Evolutive Anpassung der transkriptionellen ... [more] »

Category: CE Seminar

2010-04-22

11 May 2010, 16:30; Location: S3|05-074 (IGD)

Die dynamische Simulation ist ein aktueller Forschungsbereich mit vielen Anwendungsgebieten. Dieser Bereich umfasst u.a. die Simulation von Starrkörpern, Textilien und Weichkörpern. Dynamische Simulation ist heutzutage ein wichtiger Bestandteil im Entwicklungsprozess von komplexen Maschinen (wie z.B. in der Robotik), im Forschungsbereich der Medizin, in der ... [more] »

Category: CE Seminar

2010-04-12

7 May 2010, 15:15; Location: L1|01-K 328

Die variationelle Mehrskalen-Methode wurde vor ca. 15 Jahren zum ersten Mal der Fachwelt als theoretisches Rahmenwerk für die Entwicklung numerischer Methoden für Probleme mit sehr breiten Skalenspektren vorgestellt. Als Beispiele für solche Mehrskalen-Probleme kann man u.a. viele Problemstellungen der Materialmodellierung, aber auch z.B. turbulente ... [more] »

Category: CE Seminar

2010-01-21

6 May 2010, 17:00; Location: S2|17-103

Category: CE Seminar

2010-04-12

15 Apr 2010, 14:00; Location: S2|17-114

Category: CE Seminar

2010-04-15

23 Mar 2010, 17:15; Location: S2|17-103

Category: CE Seminar

2010-04-15

23 Mar 2010, 16:30; Location: S2|17-103

Category: CE Seminar

2010-02-03

11 Feb 2010, 17:00; Location: S4|10-1

Part 1: Singularity type functions, such as the Dirac delta, are usually defined assuming that they operate on well defined functions - usually called ‘good functions’. The results that hold for singular- ity functions, and for the good function case, do not hold, in general, for the usual case where non- good functions are to be considered and this has led ... [more] »

Category: CE Seminar

2010-01-25

26 Jan 2010, 12:00; Location: L1|08-4

Rieselfilme (d.h. dünne durch Gravitation getriebene flüssige Filme) spielen in einer Vielzahl technischer Prozesse in der Energie- und Verfahrenstechnik eine Rolle. In Kühltürmen wird z.B. Wasser auf sogenannte Rieseleinbauten gesprüht, wodurch sich ein verdunstender Film ausbildet. Rieselfilme aus flüssigem Lithium werden in der Kernfusionsforschung zur ... [more] »

Category: CE Seminar

2010-01-13

18 Jan 2010, 16:00; Location: S2|17-103

Although Boundary Element Method (BEM) requires us heavy calculation cost and large required memory, it givs us some remarkable advantages due to property of surface mesh such as in open bounary problems, moving boundary problems, optimized shape design problems, inverse problems, coupling problems with moving charged particles, and so on. This means that ... [more] »

Category: CE Seminar

2009-12-11

14 Dec 2009, 15:30; Location: S2|17-103

Airborne vehicle or and its payload are extremely expensive and their loss as a result of a nearby lightning strike is highly undesirable. Even though one could launch only under ideal weather conditions, the cost involved with long launch delays could be very high. So in this age of all weather usage of airborne launch vehicles, it has become necessary to ... [more] »

Category: CE Seminar

2009-11-17

7 Dec 2009, 17:00; Location: S4|10-1

Hearing impaired people suffer from significant problems of understanding speech in noisy environments. The damage of the outer hair cells in the cochlear causes a reduced frequency resolution or higher frequency masking of the auditory perception, respectively. The only possibility to compensate for this effect is to offer people a signal with reduced ... [more] »

Category: CE Seminar

2009-10-16

4 Nov 2009, 15:15; Location: S1|10-103

According to textbook wisdom, flow down a pipe becomes turbulent near a Reynolds number of about 2000. This simple statement misses many subtleties of the transition: the absence of a linear stability of the laminar flow, the sensitive dependence on perturbations that sometimes succed and sometimes fail to induce turbulence and the unexpected observation ... [more] »

Category: CE Seminar

2009-08-20

14 Sep 2009, 16:00; Location: S3|06-249

When we speak of cognition, we usually think of the human brain: A powerful and highly complex information-processing system. So, I set the stage for my lecture by describing the Action-Perception Cycle that is an inherent characteristic of the brain. With the Action-Perception Cycle as the focus of attention throughout the lecture, I will then describe ... [more] »

Category: CE Seminar

2009-09-07

11 Sep 2009, 15:15; Location: S2|02-A102 (Robert-Piloty-Gebäude)

Urban Search And Rescue (USAR) is a time critical task since survivors have to be rescued within the first "golden" 72 hours. One goal in Rescue Robotics is to support emergency response by mixed-initiative teams consisting of humans and robots. Their task is to explore the disaster area rapidly while reporting victim locations and hazardous areas ... [more] »

Category: CE Seminar

2009-09-07

11 Sep 2009, 08:45; Location: S2|02-A102 (Robert-Piloty-Gebäude)

Latente Variablen haben eine langjährige Geschichte in der Modellierung komplexer statistischer Zusammenhänge. Indem sie versteckte Strukturen in Daten selbständig aufgreifen und repräsentieren können, ermöglichen sie es, erstaunlich elegante und einfache Modelle einer Vielzahl komplexer Phänomene zu generieren. Klassische Beispiele für Verfahren, die auf ... [more] »

Category: CE Seminar

2009-06-24

29 Jun 2009, 11:40; Location: S3|05-074

The advances in hardware functionality and programmability of graphics processors (GPUs) have greatly increased their appeal as add-on co-processors for scientific computing. However, for large-scale computations a desktop with a single GPU is not sufficient and parallel workstations or even clusters with multiple GPUs must be considered. This talk will ... [more] »

Category: CE Seminar

2009-06-10

22 Jun 2009, 15:30; Location: S3|05-074

Flow fields play an important role in a wide range of scientific, engineering, and medical disciplines. Due to the advancements in computing technologies and computational fluid dynamics (CFD), recently we have seen a large number of flow datasets with ever increasing size and complexity from numerical fluid simulations. In order to obtain valuable ... [more] »

Category: CE Seminar

2009-05-28

17 Jun 2009, 15:15; Location: S1|03-252

Am 15. Januar 2009 gelang dem Piloten einer Maschine vom Typ A320 der US Airways nach dem Ausfall beider Triebwerke eine Notwasserung auf dem Hudson River in New York. Alle 155 Insassen überstanden die Notwasserung nahezu unverletzt. Der Vortrag behandelt einen randständigen Bereich des Flugzeugbaus, der sich mit der Notwasserung und Schwimmfähigkeit von ... [more] »

Category: CE Seminar

2009-05-11

16 Jun 2009, 17:00; Location: S4|10-1

We exploit ideas from model predictive control to construct nonlinear distributed and boundary controllers for flow governed by the instationary Navier Stokes equations or the Boussinesq approximation. We numerically test the performance of the controllers considering as example control of the wake of the circular cylinder in the laminar flow regime, and ... [more] »

Category: CE Seminar

2009-06-08

9 Jun 2009, 10:00; Location: S2|17-103

Category: CE Seminar

2009-05-26

4 Jun 2009, 10:00; Location: S3|06-146

Existing wireless networks are designed for coexistance, i.e. essentially for interference avoidance. In contrast cooperative wireless communication intentionally accepts interference to optimize network performance. In this talk we start out with a brief introduction to cooperative wireless communication and in particular wireless relaying. Subsequently ... [more] »

Category: CE Seminar

2009-05-14

20 May 2009, 15:15; Location: S1|03-252

A systematic framework for implicit LES modeling will be presented. Unlike previous approaches to ILES, where given nonlinearly stable discretizations are employed without a priori analysis of the effect of the truncation error, with the proposed framework ALDM (adaptive local deconvolution model) physically consistent modeling is introduced to ILES. With ... [more] »

Category: CE Seminar

2009-04-28

13 May 2009, 15:15; Location: S1|03-252

Spektralelementmethoden (SEM) kombinieren die Genauigkeit von Spektralmethoden mit der Flexibilität von Finite-Elemente-Verfahren. Dieser Anspruch lässt sich In der Praxis nicht immer leicht verwirklichen.

Dieser Vortrag startet mit einigen Erfolgsbeispielen aus dem SFB 609 an der TU Dresden.

Der zweite Teil widmet sich der implementierung von ... [more] »

Category: CE Seminar

2009-03-06

5 May 2009, 17:00; Location: S4|10-1

Every optimization technique has inherent strengths and weaknesses. Moreover, some optimization algorithms contain characteristics which make them better suited to solve particular kinds of problems. Hybridization, or the combining of two or more complementary, but distinct methods, allows the user to take advantage of the beneficial elements of multiple ... [more] »

Category: CE Seminar

2009-03-24

27 Apr 2009, 16:00; Location: S2|17-103

Optimization problems with partial differential equations constraints are computationally challenging problems that appear in a wide range of engineering applications. Space-mapping techniques allow to speed their solution procedure by extracting information from approximate models such as for instance analytical and lumped parameter approximations. Early ... [more] »

Category: CE Seminar

2009-03-30

16 Apr 2009, 16:00; Location: S2|17-114

The Finite Difference Time Domain (FD-TD) algorithm, originally proposed by K. S. Yee, is one of the most common algorithm for the time-domain simulation of electromagnetic problems. This is essentially due to the fact that the FD-TD algorithm is explicit, so that its computationally complexity and memory requirement are low, and to the fact that the limit ... [more] »

Category: CE Seminar

2009-03-02

9 Apr 2009, 14:30; Location: S4|10-1

We combine the classical theories of discrete computation (Turing computability and complexity classes like NP) and real number computation (Recursive Analysis and BSS model) with Theoretical Physics in order to

1. investigate physical foundations of computing (Church-Turing Hypothesis) and

2. devise a complexity theory of computer simulation ... [more] »

Category: CE Seminar

2009-02-05

12 Mar 2009, 17:00; Location: S1|03-123

Anisotropic mesh adaptation has proven to be a useful tool for enhancing accuracy and efficacy in the numerical solution of partial differential equations, especially those exhibiting anisotropic features in their solutions and/or structures. On the other hand, the mathematical characterization of anisotropic meshes has not been well understood. In ... [more] »

Category: CE Seminar

2008-11-07

5 Feb 2009, 16:00; Location: S2|17-103

The simulation of electromagnetic phenomena using field solvers for semiconductor structures demands the use of potentials and vector potentials because the local energy, more than the local force, determines the electron and hole distributions. The ideas underlying the finiteintegration method are applied to the potential fields leading to a discretization ... [more] »

Category: CE Seminar

2008-10-27

29 Jan 2009, 16:00; Location: S2|17-103

Electromagnetic modelling for photonics shares many common problems with other applications. These include the requirement for: multi-scale modelling, requiring an accurate description of small features that can have significant influence on the performance of a significantly larger system; addressing multi-physics problems operating on timescales; highly ... [more] »

Category: CE Seminar

2008-12-19

22 Jan 2009, 17:00; Location: S2|17-103

Der Vortrag gibt eine Übersicht über die Entwicklung von Discontinuous-Galerkin-Verfahren für instationäre Probleme. Durch ihre Flexibilität und die Qualität der Näherungslösungen werden diese Verfahren als eine künftige Möglichkeit gesehen, numerische Simulationen in komplexen Geometrien effizienter zu machen. Das DG-Verfahren kann als eine Kombination von ... [more] »

Category: CE Seminar

2008-11-14

18 Dec 2008, 17:00; Location: S4|10-1

Modern graphics cards are not only powerful rendering systems but can also be used as massively parallel compute devices. Applications that are well suited for the cards' SIMD architecture can achieve speed ups of more than two orders of magnitude compared to single CPU implementations. In this talk, I will give an introduction to NVIDIA's CUDA ... [more] »

Category: CE Seminar

2008-12-10

17 Dec 2008, 11:00; Location: S4|10-1

Category: CE Seminar

2008-11-05

11 Dec 2008, 17:00; Location: S2|17-103

The multilevel fast multipole algorithm (MLFMA) is a powerful method for the fast and efficient solution of scattering and radiation problems in electromagnetics. Real-life problems formulated with surface integral equations can be solved iteratively, where the required matrix-vector multiplications are performed efficiently by MLFMA. However, many ... [more] »

Category: CE Seminar

2008-10-27

4 Dec 2008, 18:00; Location: S2|17-103

Category: CE Seminar

2008-10-27

4 Dec 2008, 17:00; Location: S2|17-103

Category: CE Seminar

2008-10-07

20 Nov 2008, 17:00; Location: S2|17-103

Elektromechanische Systeme werden durch die Maxwellschen Gleichungen in Verbindung mit der Newtonschen Bewegungsgleichung beschrieben. Die physikalischen Gesetze liegen dabei in Form (partieller) Differentialgleichungen vor, die durch Anwendung numerischer Verfahren schrittweise in lineare Gleichungssysteme überführt und auf dem Rechner gelöst werden. ... [more] »

Category: CE Seminar

Technische Universität Darmstadt

Graduate School CE

Dolivostraße 15

D-64293 Darmstadt

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