Entwicklung einer Komponente zur automatisierten Adaption von Workflows (German Edition)

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This simulation calculates the changes in the energy consumption with every modification made by the planning engineer, in the background and in real time. Thus, this model allows a priori prediction of the energy consumption dur-ing the planning phase, in contrast to other existing approaches that only allow a posteriori calculations during the operational phase. Additionally, we will present ideas for energy optimisation, in particular, an automatic energy optimisation approach based on an ant colonisation algorithm.

Weak imposition of contact constraints on automatically recovered high order embedded interfaces In: A high-order accurate computational framework for the simulation of SLM processes In: High order fictitious domain methods - high fidelity simulation for complex solid models In: Third International Conference on Railway Technology: Research, Development and Maintenance, - Status: Classically, objects are defined by a Boundary Representation B-Rep , where only the objects surfaces with their corresponding edges and nodes are stored.

One disadvantage concerning a numerical simulation is that B-Rep models are not necessarily water-tight. In this context, the model is created using Boolean operations on primitives. To run a finite element simulation on a water-tight CSG model, two alternatives are possible: A crucial point in FCM is a fast and reliable point-in-membership test which can be directly derived from the CSG model. We present the outline of the modeling approach, the realization of the point-in-membership test as a sequence of CSG-operations, and discuss advantages and limitations on complex models of relevance in mechanical engineering.

Multi-level hp-adaptivity and the finite cell method for fluid problems In: Im vorliegenden Beitrag werden diese deshalb mit Hilfe eines Optimierungsverfahrens festgelegt. Dieser wurde messtechnisch untersucht und mit finiten Elementen hoher Ordnung simuliert. Die zu minimierende Zielfunktion wird durch den quadratischen Mittelwert RMS-Wert der prozentualen Abweichungen der berechneten Eigenfrequenzen beschrieben. Da auch Aspekte des Aufbaus von Brettsperrholz-Elementen, wie z. Dabei wird das globale Minimum durch schrittweise Auswertung der Zielfunktion bestimmt, wobei die jeweils folgende Stelle auf Grundlage der bereits bekannten Funktionswerte berechnet wird.

Hierdurch konnte ein RMS-Wert von unter 5 erzielt werden. We present a detailed analysis of the convergence properties of the finite cell method which is a fictitious domain approach based on high order finite elements. Several numerical examples in one and two dimensions including a well-known benchmark problem from linear elasticity confirm the results of the mathematical analysis of the finite cell method. Yosibash, Zohar; Wille, Hagen; Rank, Ernst Show abstract Stochastic description of the peak hip contact force during walking free and going upstairs Journal of Biomechanics 48, pp.

Uncertainty quantification for the response of a patient specific femur is mandatory when advocating finite element FE models in clinical applications. Reliable stochastic descriptions of physiological hip contact forces are an essential prerequisite for such an endeavor. We therefore analyze the in-vivo available data of seven individuals from HIP98 and OrthoLoad with the objective of characterizing the variability of the peak hip contact force magnitude and two corresponding spatial angles in sagittal and frontal plane during walking free and going upstairs.

Regression analyses with linear mixed-effects models were performed resulting in six normal random variables, one for each force component and activity. Importantly, the statistical analysis accounts for the fact that same individuals performed both activities. The mean of the peak force magnitude was found to be linearly dependent on the body weight with an additional, activity-specific intercept and all variances were dominated by the inter-patient variability.

No distinct correlation was found between the two angles and the force magnitude. The proposed stochastic description of the peak hip contact force during walking free and going upstairs contributes towards future uncertainty quantification of patient-specific FE models. The development of parallel Computational Fluid Dynamics CFD codes is a challenging task that entails efficient parallelization concepts and strategies in order to achieve good scalability values when running those codes on modern supercomputers with several thousands to millions of cores.

The newly designed data structure is specifically designed with the idea of interactive data exploration and visualization during runtime of the simulation code; a major shortcoming of traditional high-performance computing HPC simulation codes. One question in the context of immersed boundary or fictitious domain methods is how to compute discontinuous integrands in cut elements accurately.

A frequently used method is to apply a composed Gaussian quadrature based on a spacetree subdivision. Although this approach works robustly on any geometry, the resulting integration mesh yields a low order representation of the boundary.

If high order shape functions are employed to approximate the solution, this lack of geometric approximation power prevents exponential convergence in the asymptotic range. In this paper we present an algorithmic subdivision approach that aims to be as robust as the spacetree decomposition even for close-to-degenerate cases—but remains geometrically accurate at the same time.

Based on 2D numerical examples, we will show that optimal convergence rates can be obtained with a nearly optimal number of integration points. The implementation of hp-adaptivity is challenging as hanging nodes, edges, and faces have to be constrained to ensure compatibility of the shape functions.

For this reason, most hp-code frameworks restrict themselves to 1-irregular meshes to ease the implementational effort. This work alleviates these difficulties by introducing a new formulation for high-order mesh adaptivity that provides full local hp-refinement capabilities at a comparably small implementational effort.

Its main idea is the extension of the hp-d method such that it allows for high-order overlay meshes yielding a hierarchical, multi-level hp-formulation of the Finite Element Method. This concept enables intuitive refinement and coarsening procedures, while linear independence and compatibility of the shape functions are guaranteed by construction. The proposed method is demonstrated to achieve exponential rates of convergence for problems with non-smooth solutions, is used alongside the Finite Cell Method to simulate the heat flow around moving objects on a non-conforming background mesh and is combined with an energy-based refinement indicator for automatic hp-adaptivity.

Contact problems in solid mechanics are traditionally solved using the h-version of the finite element method. The constraints are enforced along the surfaces of e. Standard constraint algorithms include penalty methods, Lagrange multiplier methods and combinations thereof. For complex scenarios, a major part of the solution time is taken up by operations to identify points that come into contact. This paper presents a novel approach to model frictionless contact using high order finite elements. Here, we employ an especially designed material model that is inserted into two- respectively three- dimensional regions surrounding contacting bodies.

Contact constraints are thus enforced on the same manifold as the accompanying structural problem. The application of the current material formulation leads to a regularization of the Karush-Kuhn-Tucker conditions. Our formulation can be classified as a barrier-type method. Results are obtained for two- and three-dimensional prob- lems, including a Hertzian contact problem. Comparisons to a commercial FEA package are provided. The proposed formulation works well for non-matching discretizations on adjacent contact interfaces and handles self-contact naturally.

Since the non-penetrating conditions are solved in a physically consistent man- ner, there is no need for an explicit contact search. Show abstract Finite Cell Method: High order structural dynamics for complex geometries International Journal for Structural Stability and Dynamics 15 7 , pp. In this contribution, the finite cell method FCM is applied to solve transient problems of linear elastodynamics. Semi-discrete time integration schemes are briefly discussed, and the choice of implicit time integration is justified. A one-dimensional benchmark problem is solved using FCM, illustrating the method's ability to solve problems of linear elastodynamics obtaining high rates of convergence.

Furthermore, a numerical example of transient analysis from an industrial application is solved using FCM. The numerical results are compared to the results obtained using state-of-the-art commercial software, employing linear finite elements, in conjunction with explicit time integration. The results illustrate the potential of FCM as a powerful tool for transient analysis in elastodynamics, offering a high degree of accuracy at a moderate computational effort.

Small and large deformation contact simulation using the finite cell method In: Show abstract Loading simulation of spinal vertebrae using the finite cell method In: Osteoporosis compromises bone strength, increasing the risk of vertebral fractures with severe health consequences. The development of an accurate and reliable patient-specific vertebral model would be of major clinical relevance, for both the prognosis of fractures and the investigation of implant systems.

In the case of spinal fusion, the peri-implant bone strains are of major interest. High forces are transmitted at the bone-implant interface and screw loosening is the major cause of surgical failure. In recent years, the finite element method has been increasingly applied to predict the biomechanical response of vertebrae. In general, quantitative CT-data is used to retrieve the geometric model and the inhomogeneous material properties. A finite element mesh is then generated for the numerical simulation.

For the finite element analysis of a bone-implant system, the adequate treatment of the bone-implant interface demands the adaptive refinement of the finite element mesh for an accurate solution. In this contribution, the finite cell method FCM , a high order embedded domain approach, is applied to simulate the biomechanical behavior of human vertebrae. The recently developed multi- level hierarchical refinement is used to enrich the FCM, allowing to resolve the highly inhomogeneous material properties of vertebrae.

For the simulation of bone-implant systems, the hierarchic refinement is used to resolve the bone-implant interface appropriately. The feasibility of using FCM for predicting the biomechanical response of human vertebrae is demonstrated with numerical examples on both intact and fused vertebral segments. Furthermore, the inherent hierarchical nature of the FCM strongly supports verification and validation. Fluid Flow through Porous Media: Coupling of micro- and macro-scale fluid flow models In: Show abstract Coupling scales and adaptive refinement for simulation of bone-fixation interfaces using the Finite Cell Method In: In recent years many studies on the numerical simulation of bone-implant systems have been presented.

In general, a geometric model of a bone is derived from qCT-data, including its highly inhomogeneous material properties. Bone and implant are then meshed and simulated by finite elements. In the case of a fixation the zone of the bone close to the screw is of major interest. High forces are transmitted here and screw loosening is the major cause of surgical failure.

As the scale of interest for this interface region may be several orders of magnitude smaller than that of the bone, an adaptive refinement of the finite element mesh is mandatory for an accurate solution. Whereas this is already quite demanding in cases of a single simulation, it becomes prohibitively expensive if a sequence of many simulations in order to optimize type, position and pre-stress of an instrumentation shall be performed.

In this paper we will extend the recently developed Finite Cell Method, a high order embedded domain approach by a hierarchical refinement strategy in the regions of interest. Whereas the concept of the FCM completely relieves from the need to generate a finite element mesh, the hierarchical refinement yields an accuracy and a scale resolution which could not obtained by classical finite elements methods.

We will discuss the basic properties of this adapted multi-scale method and demonstrate its feasibility for simulating bone-mechanics on the example of the fixation of a spinal segment. Show abstract The Finite Cell Method: Some Principles and Recent Progress In: The finite cell method FCM is a combination of a fictitious domain approach with finite elements of high order.

The physical domain is embedded into an easy to mesh bigger computational domain. The geometry of the problem is only considered during the integration of the cell matrices. To this end an indicator function is introduced being equal to 1 inside the physical domain. Outside it is set in order to avoid conditioning problems to a very small value. The contribution of the fictitious domain is thus penalized, shifting the effort of meshing towards the numerical integration of the cell matrices. Combining these ingredients, an exponential rate of convergence can be observed for smooth problems, when performing a p-extension.

In combination with the blending function method, this algorithm yields a nearly exact decomposition of the cut cells. Our approach is able to resolve close-to-degenerate cases, but remains algorithmically simple at the same time. Several further recent developments of the FCM will be discussed. A new two- and three-dimensional hierarchical refinement strategy yields exponential rate of convergence in energy norm even for singular problems, and its simple algorithmic structure allows an easy extension to transient problems with local refinement and de-refinement.

Enhancing the predictive capability of patient-specific simulation of human femurs with uncertainty quantification In: Coupling micro- and macro- scale on geometrically complex domains In Proc.

Bachelor-Thesis

Uncertainty quantification for patient-specific simulation of femurs based on polynomial chaos In: Interaktive Planung von U-Bahn-Tunneln: Forum Bauinformatik in Aachen, - Status: Show abstract A high-order enrichment strategy for the finite cell method In: Thanks to the application of the immersed boundary approach in the finite cell method, the mesh can be defined independently from the geometry.

Although this leads to a significant simplification of the mesh generation, it might cause difficulties in the solution. One of the possible difficulties will occur if the exact solution of the underlying problem exhibits a kink inside an element, for instance at material interfaces. In such a case, the solution turns out less smooth — and the convergence rate is deteriorated if no further measures are taken into account. In this paper, we explore a remedy by considering the partition of unity method.

The proposed approach allows to define enrichment functions with the help of a high-order implicit representation of the material interface. Wanga, Yang; Zhao, Fu-Yun; Kuckelkorn, Jens; Spliethoff, Hartmut; Rank, Ernst Show abstract School building energy performance and classroom air environment implemented with the heat recovery heat pump and displacement ventilation system Applied Energy , pp.

Recent built low energy school buildings have adopted a novel heat recovery heat pump and classroom ventilation system. School building energy conservation performance and classroom air quality enhancement will be simultaneously investigated in the present work. Heat recovery efficiency of the heat recovery facility and energy conservation ratio of the heat pump unit were analytically modeled, taking the classroom ventilation network into account.

Following that, classroom displacement ventilation and its thermal stratification have been investigated concerning the effects of delivering ventilation flow rate and supplying air temperature. Representative thermal comfort parameters, percentage dissatisfied, temperature difference between ankle and head, and draft dissatisfaction have been evaluated. Indoor air quality indicated by the CO2 concentration was also investigated in terms of different levels of ventilation flow rate. Classroom energy demands for ventilation and winter heating have been shown to decrease with the promotion of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the heat pump increases with temperature of supplying fresh air.

Detailed correlations of heat recovery ventilation and heat pump energy conservation have been presented. This research illuminated that enhancement of classroom air quality and reduction of school building energy consumption could be simultaneously achieved with the appropriate operation of heat recovery heat pump and ventilation system. Synchronous collaborative tunnel design based on consistency-preserving multi-scale models Advanced Engineering Informatics, - Status: Show abstract Using the finite cell method to predict crack initiation in ductile materials Computational Materials Science 82, pp.

In this paper, the Finite Cell Method FCM is used to predict the crack evolution in ductile materials under small strains and nonlinear isotropic hardening conditions. The FCM is the result of combining the p-version finite element and fictitious domain methods, and has been shown to be effective in solving problems with complicated geometries for which the meshing procedure can be quite expensive.

The crack evolution is introduced to the constitutive equations by using the simplified Lemaitre ductile damage model. The performance of the method is verified by means of two numerical examples in both 2D and 3D problems. Practice and Experience 15 1 , pp. Computational fluid dynamic CFD computations are memory and time intensive and need to be executed in parallel for larger computational domains. In order to produce physical accurate solutions, adaptive grid setups have to be chosen as the memory and computing time would otherwise be too high, and results would not be obtained in a reasonable amount of time.

This paper describes the usage of a multi-grid based approach for solving the pressure Poisson equation, arising during every time step of the Navier-Stokes equations. It will then highlight an analysis of errors introduced due to an adaptive setup of the domain, and show performance measurements for uniform and adaptive grid setups. Automated high-order hexahedral mesh generation for shell-like structures Engineering with Computers 30 1 , pp. This paper presents a fully automated high-order hexahedral mesh generation algorithm for shell-like structures based on enhanced sweeping methods.

Traditional sweeping techniques create all-hexahedral element meshes for solid structures by projecting an initial single surface mesh along a specified trajectory to a specified target surface. The work reported here enhances the traditional method for thin solids by creating conforming high-order allhexahedral finite element meshes on an enhanced surface model with surfaces intersecting in parallel, perpendicular and skew-angled directions. The new algorithm is based on cheap projection rules separating the original surface model into a set of disjoint single surfaces and a so-called interface skeleton.

The core of this process is reshaping the boundary representations of the initial surfaces, generating new sweeping templates along the intersection curves and joining the single swept hex meshes in an independently generated interface mesh. The Finite Cell Method FCM combines the high-order finite element method and the fictitious domain approach for the purpose of simple meshing.

The numerical results show that the FCM is more efficient compared to h-FEMfor elasto-plastic problems, although the mesh does not conform to the boundary. It is also demonstrated that the FCM performs well for elasto-plastic loading and unloading. Dynamic analysis of high loaded components, discretized by fictitious domain methods In: A proposal for an improved IFC 4 based alignment model for infrastructure design In: Computational Fluid Dynamics Framework In: A macro- and micro-scale In: Show abstract Interactive data exploration for high-performance fluid flow computations through porous media In Proc.

Journal-Artikel (Peer Reviewed) - Otto-Friedrich-Universität Bamberg

Huge data advent in high-performance computing HPC applications such as fluid flow simulations usually hinders the interactive processing and exploration of simulation results. Therefore, we propose an HPC data exploration service based on a sliding window concept, that enables researches to access remote data available on a supercomputer or cluster during simulation runtime without exceeding any bandwidth limitations between the HPC back-end and the user front-end.

Interaktive Planung von U-Bahn Tunnels: Forum Bauinformatik Darmstadt, - Status: Show abstract High order Finite Elements for mid-frequency vibro-acoustics In: Dynamics, Porto, Portugal, Loading Bibtex The quantification of vibroacoustic properties in multi-floor timber buildings is currently still based on measurements and computational models are rarely used in practice. One reason surely is a lack of validated and robust numeric schemes for vibro-acoustic simulations covering mid-range frequencies which can be integrated smoothly into the planning process of multi-floor timber buildings.

To this end, we lay out a pipeline for the prediction of mid-frequency vibro-acoustic behavior of laminated timber constructions by modal analysis using three-dimensional high-order finite elements. The integration into the planning process is achieved by deriving the computational model from IFC-based building information models. High Performance Visual Computing: Coupling micro- and macro-scale In: Show abstract Monitoring healing processes in bones using the adjoint method In: One goal of non-destructive testing procedures is the identification of changes of interior details of a structure over time.

More general, the deviation of the present state of a structure from a measured or simulated model state has to be identified. These and similar problems occur in different areas of natural sciences, engineering and technology, where geophysics, biomechanical engineering and Structural Health Monitoring are only a few examples. Over the last decade newly developed numerical methods in geophysics allow to identify the interior of the earth in much more detail than ever before [1].

Their dramatic progress is based on smart combinations of detailed seismic measurements, advanced mathematical approaches and efficient algorithms for high performance computing [2].

We present our attempts to transfer and further develop these methods to problems in biomechanics with the goal to monitor healing processes of fractured bone. To this end we investigate the so-called adjoint method, using a numerical bone model which stems from a CT scan of the damaged bone, an acoustic simulation based on this model and synthetic measurements obtained during the healing process. Because the wave equation is symmetric in time, the propagation of sound is time-reversible [3].

Therefore, the differences of simulated and generated signals at the receiver locations can be time-reversed and played backward into the model. Within the backward simulation sensors become sources and the wave fronts focus on the location of differences in the bone density, being the origin of the difference in the signals.

Using the results of this simulation, we construct a sensitivity kernel highlighting the regions of maximal change of material parameters. We illustrate the potential of this approach on numerical experiments with a synthetic model and show that it could open the possibility to reduce cost and radiation exposure by reducing the number of necessary CT scans without compromising the quality of monitoring of the healing process.

The AGENT simulation system is used for detailed three-dimensional modeling of neutron transport and corresponding properties of nuclear reactors of any design. The latter of which is used for accurately describing current and future heterogeneous lattices of reactor core configurations. The AGENT code has been extensively verified to assure a high degree of accuracy for predicting neutron three-dimensional point-wise flux spatial distributions, power peaking factors, reaction rates, and eigenvalues.

This new feature provides a novel way for using deterministic codes for fast evaluation of reactor core parameters, at no loss to accuracy.

This framework allows for an arbitrary interruption of AGENT simulation, allowing the solver to restart with updated parameters. One possible use of this is to accelerate the convergence of the final values resulting in significantly reduced simulation times. The utility of the steering framework is demonstrated using the geometry of a research reactor at the University of Utah: Show abstract The method of separation for evolutionary spectral density estimation of multi-variate and multi-dimensional non-stationary stochastic processes Probabilistic Engineering Mechanics, Loading Bibtex The method of separation can be used as a non-parametric estimation technique, especially suitable for evolutionary spectral density functions of uniformly modulated and strongly narrow-band stochastic processes.

The paper at hand provides a consistent derivation of method of separation based spectrum estimation for the general multi-variate and multi-dimensional case. The validity of the method is demonstrated by benchmark tests with uniformly modulated spectra, for which convergence to the analytical solution is demonstrated. The key advantage of the method of separation is the minimization of spectral dispersion due to optimum time- or space-frequency localization. This is illustrated by the calibration of multi-dimensional and multi-variate geometric imperfection models from strongly narrow-band measurements in I-beams and cylindrical shells.

Finally, the application of the method of separation based estimates for the stochastic buckling analysis of the example structures is briefly discussed. Show abstract History source identification of airborne pollutant dispersions in a slot ventilated building enclosure International Journal of Thermal Sciences 64 2 , pp. The backward time modeling of diffusion—convection pollutant dispersions has been developed with quasi-reversibility method in this work. The procedure is applied to the backward time identification of the contaminant release history and source location in a three-dimensional slot ventilated building enclosure.

Spatial distributions of pollutant concentrations are known in priori. The effects of supplying air velocity, pollutant source location, pollutant diffusivity property, and pollutant release time on the accuracy of the pollutant dispersion history recovery have been investigated. Numerical results demonstrate that the accuracy of the pollutant dispersion history recovery can be enhanced with different approaches and measures, including the promotion of room ventilation rate, the shrinkage of distance between the pollutant source and supplying air port, and the reduction of pollutant diffusivity.

The facilitated implementations of boundary conditions and the improved generality of quasi-reversibility methods make the pollutant source history identifications of less computational efforts.

Particularly, the good agreement of the backward time identified source location with the true situation fully shows that quasi-reversibility method is more competitive in the engineering applications involving with convective fluid flows. From Visualisation to Simulation: Weak Dirichlet-type boundary conditions are especially important in embedded domain methods such as the Finite Cell Method. Well suited are Nitsche-type methods which have been extended to problems of linear elasticity or fluid dynamics. In principle, they consist of two parts.

The first part is negative and stems from an suitable Lagrange multiplier. The second part is positive and stems from the minimization of the difference between the primal solution at the boundary minus the imposed values. It is penalty like in nature but acts as a stabilization and ensures coercivity of the system matrix. This penalty part contains a free penalty parameter, which has to be chosen a-priori. Alternatively, the necessary stabilization parameter may also be computed by solving an auxiliary eigenvalue problem.

Recently, an attractive alternative was presented in the context of low order methods. It utilizes the same idea of identified Lagrange multipliers as in Nitsche's method, but replaces the penalty terms using the condition that the multiplier is the normal trace of the flux of the unknown in a least squares sense. We will present an analysis on the performance on this new type of conditions for the Finite Cell Method in the context of p-FEM and Isogeometric Analysis. Further, we have utilized this method to derive a new formulation for parameter-free coupling of trimmed NURBS.

We will show some preliminary results for coupled problems in one and two dimensions for Poisson's equation and for linear elasticity. Parallel multi-grid like solver for the pressure Poisson equation in fluid flow applications In: Sliding Window Data Transfer In: Forum Bauinformatik, - Status: Ein konkreter Prototyp dieser Kollaborationsplattform soll die theoretischen Konzepte anschaulich demonstrieren. Welche Entwurfsmuster in unserem Fall zur erfolgreichen Entwicklung des Prototyps beitragen, ist der Kern dieses Papers.

Intelligent Computing In Engineering, - Status: Planning inner-city-railway-tracks is an interdisciplinary and highly complex task that involves plenty of different stakeholders. Currently, the different planners work more or less separated in an asynchronous manner. To facilitate a collaborative planning process between these different stakeholders we developed a collaboration platform. Clearly, the integration of geographical information and geoprocessing results into the planning process respectively the different modelling tools, improves this process in a significant way.

In this paper, we will show how to describe the needed geographical information in a suitable way and how to integrate these pieces of information into the different planning tools via the collaboration platform in a unified, dynamic, and generic way. For realizing data exchange in the context of planning and realization of large infrastructure projects, a comprehensive neutral data model capable to present both semantic as well as geometric aspects is necessary.

The Industry Foundation Classes IFC provide a full-grown and standardized product model for the design and engineering of buildings. In the infrastructure sector, a comparably powerful data exchange solution is still missing. To fill this gap, this paper presents an alignment model which is based on the IFC data model and can be used as a data exchange standard for the design and maintenance of linear infrastructure facilities like roads, bridges and tunnels. The paper presents in detail the results of our data modeling activities. In particular, we demonstrate the use of the alignment sub-model by integrating it with a refined version of an existing shield tunnel product model.

The proposed product model provides semantic entities, models the relationships between the physical objects and makes extensive use of the space aggregation concept inherited from standard IFC. Show abstract Towards a stochastic model for the hip contact force In: Towards this aim, patient-specific finite element simulations based on qCT scans were developed [Keyak , Yosibash , Trabelsi ].

These models are deterministic and require assumptions on geometry, material properties, and boundary conditions, which are mostly uncertain. This study investigates the uncertainty related to the hip contact force during walking free and going upstairs. Together with the uncertainty of the elastic property of human femurs [Wille ], such a stochastic model will allow to quantify both the mechanical behavior and its reliability.

A framework for the interactive handling of high-dimensional simulation data in complex geometries In: The ever-increasing advances in computer technology have encouraged many in science and engineering to apply numerical methods to simulate large problems. The role of interactive computing environments, allowing for exploration of the computational model "on the fly", simultaneously providing insight into the computational experiment, as well as opportunity to react on changes, increases - however, bringing forth new challenges due to the complexity requirements and amount of data in numerical simulations.

Namely, in order to keep the exploration process comfortable and intuitive, i. In addition to this, the dynamicity of the overall process has to be taken into account, which would make the implementation of dynamic load balancing strategies both computation and communication overhead prone. We present static load balancing strategy used in our interactive distributed bone structure simulation environment, which, inspired by already acknowledged optimization techniques, keeps the work load among all the processes well balanced throughout the program execution. Promising speedup results indicate that, by exploiting even more computational resources, several updates per second could be achieved, also for very high-accuracy simulations of bone stresses.

Modeling on indoor air quality is performed considering the effect of a new window-type air conditioner, which is a promising way toward compromising energy consumption and residential air environment. Sensitivity analysis of the actual operating situations has been implemented, including the total fresh air supply and the full room air recirculation. The effects of supplying air flow rate, pollutant filtration efficiency, and indoor thermal buoyancy on the airborne pollutant transports are also illustrated.

The numerical results demonstrate that the reduction of indoor pollutant levels can be accomplished either by increasing the fresh air ratio, or by increasing filtered removal efficiency, or by increasing the supplying airflow rate, or by decreasing the strength of indoor heating source. The indoor contaminant concentration asymptotically approaches to a small value for the situation of full fresh air supply, which agrees well with the analytical solutions of indoor contaminant concentration under the extreme operations.

Slot ventilated enclosure flows have been simulated, respectively in displacement ventilation and mixed ventilation covering from the forced convection dominated flow to the natural convection dominated flow. Direct convection simulation together with the turbulent streamlines and turbulent heatlines demonstrate that the enclosure flow pattern, indoor thermal level and heat transfer potential will depend on the interactions of external forced flow and thermal buoyancy driven flows, i. In subsequent inverse convection modeling, the inverse determination of enclosure wall heat flux profiles was conducted by the use of adjoint methodology, in which the direct, sensitivity and adjoint problems are formulated and solved by finite volume method.

The effects of the supplying air flow rate, thermal source strength, ventilation mode, flux functional forms, and the measurement errors on the accuracy of inverse turbulent convection estimation have been investigated. The inverse solutions of turbulent convections are of low level accuracy as the flow becomes thermal-driven turbulent flows, and they deteriorate as the noise levels increase.

This work is of fundamental importance for the room air flow design and measurements involving the turbulent thermal convections. Show abstract Comparison of Eigenmode based and random field based imperfection modeling for the stochastic buckling analysis of I-section beam-columns International Journal of Structural Stability and Dynamics, Loading Bibtex The uncertainty of geometric imperfections in a series of nominally equal I-beams leads to a variability of corresponding buckling loads.

FFG Projektdatenbank

Its analysis requires a stochastic im- perfection model, which can be derived either by the simple variation of the critical Eigenmode with a scalar random variable, or with the help of the more advanced theory of random fields. The present paper first provides a concise review of the two different modeling approaches, covering theoretical background, assumptions and calibration, and illustrates their integration into commercial finite element software to conduct stochastic buckling analyses with the Monte Carlo method.

The stochastic buckling behavior of an example beam is then simulated with both stochastic models, calibrated from corre- sponding imperfection measurements. The simulation results show that for different load cases, the response statistics of the buckling load obtained with the Eigenmode based and the random field based models agree very well.

A comparison of our simulation results with corresponding Eurocode 3 limit loads indicates that the design standard is very conservative for compression dominated load cases. We explore hierarchical refinement of NURBS as a basis for adaptive isogeometric and immersed boundary analysis. We use the principle of B-spline subdivision to derive a local refinement procedure, which combines full analysis suitability of the basis with straightforward implementation in tree data structures and simple generalization to higher dimensions. We test hierarchical refinement of NURBS for some elementary fluid and structural analysis problems in two and three dimensions and attain good results in all cases.

Using the B-spline version of the finite cell method, we illustrate the potential of immersed boundary methods as a seamless isogeometric design-through-analysis procedure for complex engineering parts defined by T-spline CAD surfaces, specifically a ship propeller and an automobile wheel. We show that hierarchical refinement considerably increases the flexibility of this approach by adaptively resolving local features. An efficient integration technique for the voxel-based finite cell method International Journal for Numerical Methods in Engineering 91 5 , pp.

The Finite Cell Method FCM is an embedded domain method, which combines the fictitious domain approach with high-order finite elements, adaptive integration, and weak imposition of unfitted Dirichlet boundary conditions. For smooth problems, FCM has been shown to achieve exponential rates of convergence in energy norm, while its structured cell grid guarantees simple mesh generation irrespective of the geometric complexity involved.

The present contribution first unhinges the FCM concept from a special high-order basis. Several benchmarks of linear elasticity and a complex proximal femur bone with inhomogeneous material demonstrate that for small deformation analysis, FCM works equally well with basis functions of the p-version of the finite element method or high-order B-splines. Turning to large deformation analysis, it is then illustrated that a straightforward geometrically nonlinear FCM formulation leads to the loss of uniqueness of the deformation map in the fictitious domain.

Therefore, a modified FCM formulation is introduced, based on repeated deformation resetting, which assumes for the fictitious domain the deformation-free reference configuration after each Newton iteration. Numerical experiments show that this intervention allows for stable nonlinear FCM analysis, preserving the full range of advantages of linear elastic FCM, in particular exponential rates of convergence. Finally, the weak imposition of unfitted Dirichlet boundary conditions via the penalty method, the robustness of FCM under severe mesh distortion, and the large deformation analysis of a complex voxel-based metal foam are addressed.

Show abstract Prediction of the mechanical response of the femur with uncertain elastic properties Journal of Biomechanics 45 7 , pp. A mandatory requirement for any reliable prediction of the mechanical response of bones, based on quantitative computer tomography, is an accurate relationship between material properties usually Young's modulus E and bone density?. The first goal of this study is to pool and analyze the relevant available experimental data and develop a stochastic E-? The second goal is to use the newly developed stochastic E-?

When compared with the experimental observations, the FEA predictions using the median of the stochastic E-? Thus, most deviations of the FEA predictions from experimental observations can possibly be explained by uncertain elastic properties of the femur. While previous publications concentrated on single-field applications, this paper demonstrates that the advantages of the method carry over to the multi-physical context of linear thermoelasticity. The ability of the method to converge with exponential rates is illustrated in detail with a benchmark problem.

Table of contents

A second example shows that the Finite Cell Method correctly captures the thermoelastic state of a complex problem from engineering practice. Both examples additionally verify that, also for two-field problems, Dirichlet boundary conditions can be weakly imposed on non-conforming meshes by the proposed extension of Nitsche's Method.

Geometric modeling, isogeometric analysis and the finite cell method Computer Methods in Applied Mechanics and Engineering 0 , pp. Show abstract Dual steady transports of heat and moisture in a vent enclosure with all round states of ambient air International Journal of of Heat and Mass Transfer 55 11 , pp. Combined natural convective heat and moisture transports in a moist-air-filled enclosure with four free vent ports are numerically investigated.

Book Contributions

Convective transports of semi-enclosed air, heat and moisture are respectively analyzed using the contours of streamfunction, heatfunction and massfunction, in addition to the isotherms and iso-concentrations. Overall convective heat transfer rate Nu and moisture transfer rate Sh of the internal concentrated heat and moisture source have been correlated with the thermal Rayleigh number respectively within the domain of the heat transfer driven flows and that of moisture transfer driven flows.

When different initial convective flow conditions were imposed in the cases I and IV , dual steady flow states of semi-enclosed heat and moisture convection are observed, and heat and moisture transport potentials can be enhanced or inhibited depending on the flow solution branches. These results can be adopted to guide the design of natural ventilation in the humid regions. This framework allows for the arbitrary interruption of any simulation system for the purpose of modifying internal state. Once the simulation is interrupted, the solver, meshing and resolution parameters, and convergence variables can all be modified to more appropriate values.

Depending which settings have been modified, remeshing and refined resolution are then performed, and values are copied from the old set of resolution parameters onto the new set. Then the simulation restarts at whatever state - for example, timestep - it reached previously, without requiring a resubmission into the job control system. In this paper we present an example in which initially the mesh resolution of the UUTR core input set up with a wide ray separation of 1.

Thus, using the aforementioend computational steering framework, the simulation is interrupted after iterations. The ray separation is then changed to a smaller value and after iterations the solution meets the required convergence criteria. The second example illustrates how the user can accelerate the convergence: There is a significant reduction in the CPU time The hydroelastic response of very large floating structures VLFS is obtained by resolving the interaction between the surface waves and the floating elastic body.

We carry out the analysis in the frequency domain, assuming that the surface waves can be described by a directional wave spectrum. Applying the modal expansion method, we obtain a discrete representation of the required transfer matrices for a finite number of frequencies, while the influence of the wave direction is obtained by numerical integration of the directional components of the spectrum.

The boundary element method is used to solve the Laplace equation together with the fluid boundary conditions for the velocity potential, whereas the finite element method is adopted for solving the deflection of the floating plate. Moreover, we compute the variance of the response for two different cases of mean wave angles. In this paper, we present a variationally consistent formulation for the weak enforcement of essential boundary conditions as an extension to the finite cell method, a fictitious domain method of higher order.

The absence of boundary fitted elements in fictitious domain or immersed boundary methods significantly restricts a strong enforcement of essential boundary conditions to models where the boundary of the solution domain coincides with the embedding analysis domain.

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Penalty methods and Lagrange multiplier methods are adequate means to overcome this limitation but often suffer from various drawbacks with severe consequences for a stable and accurate solution of the governing system of equations. In this contribution, we follow the idea of NITSCHE who developed a stable scheme for the solution of the Laplace problem taking weak boundary conditions into account.

An extension to problems from linear elasticity shows an appropriate behavior with regard to numerical stability, accuracy and an adequate convergence behavior. NURBS are chosen as a high-order approximation basis to benefit from their smoothness and flexibility in the process of uniform model refinement. In this paper, an approach on performing numerical multi-scale simulations on fine detailed geometries is presented.

In particular, the focus lies on the generation of sufficient fine mesh representations, whereas a resolution of dozens of millions of voxels is inevitable in order to sufficiently represent the geometry. Furthermore, the propagation of boundary conditions is investigated by using simulation results on the coarser simulation scale as input boundary conditions on the next finer scale.

Finally, the applicability of our approach is shown on a two-phase simulation for flooding scenarios in urban structures running from a city wide scale to a fine detailed in-door scale on feature rich building geometries. Since the early years of computational engineering, the classical Finite Element Method FEM has become the state-of-the-art approach to solve initial boundary value problems numerically.

Although major enhancements allowed for highly sophisticated simulations, the idea to geometrically resolve the physical domain on the discretization level remained unchanged. The approach embeds the possibly complex physical domain phys in a fictitious domain? Recent research results confirm the excellent applicability of this new method in the fields of non-linear continuum mechanics, topology optimization, thin-walled structures, bone mechanics and advection-diffusion problems. In the present work, the Finite Cell Method is employed to solve the transient, non-linear heat equation on non-conforming meshes.

In particular, the weak enforcement of Dirichlet boundary conditions is addressed. The results of a conventional p-FEM simulation serve as reference and the convergence characteristics of both approaches are compared. Very large floating structures VLFSs have been used for broad applications such as floating storage facilities, floating piers, floating bridges, floating airports, entertainment facilities, even habitation, and other purposes.

Owing to its small bending rigidity, VLFS deforms elastically when subjected to wave action. This elastic deformation due to wave is called hydroelastic response and it can be obtained by solving the interaction between the surface wave and the floating structure in the frequency domain. In solving the fluid-structure interaction, the floating structure can be modelled by applying the finite element method, whereas the fluid part may be analyzed by using the Green's function method. When using the Green's function which satisfies the boundary condition on the free-surface, the sea bottom and that at infinite distance from the floating structure, the unknown parameters to be determined for the fluid part can be minimized to be only those associated with the wetted surface of the floating structure.

Therefore, acceleration techniques are necessary to tackle the computational complexity. Nowadays, standard multi-core office PCs are already quite powerful if all the cores can be used efficiently. This paper will show different parallelisation strategies for speeding up the Green's function computation. A shared memory based implementation as well as a distributed memory concept will be analysed regarding speed-up and efficiency. For large computations, batch jobs can be used to compute detailed results in high resolution on a large computational cluster or supercomputer.

Different speed-up computations on clusters will be included for showing strong speed-up results. Computational Fluid Dynamics simulations require an enormous computational effort if a physically reasonable accuracy should be reached. Therefore, a parallel implementation is inevitable. This paper describes the basics of our implemented fluid solver with a special aspect on the hierarchical data structure, unique cell and grid identification, and the neighbourhood relations inbetween grids on different processes.

Dissertation, Dresden, November , Qucosa http: Leitfaden interoperable Assistenzsysteme - vom Szenario zur Anforderung. PhD thesis, Dresden, December , Qucosa http: Erweiterte Trace-Analyse in Test und Diagnose. Grundlage eines neuen Informationsbegriffs mit konkreten Anwendungen in Methodik und Praxis der Informatik. The Industrial Electronics Handbook, J. Dissertation, Vogt Verlag, Auflage in chinesischer Sprache Towards a holistic platform for runtime adaptation and reconfiguration of building automation systems.

Proceedings of the 16th European advanced process control and manufacturing apc m Conference, Reutlingen Germany , April Innovation Day Abstracts, pp. Proceedings of the 15th European advanced process control and manufacturing apc m Conference, Freising Munich , April Journal of Computational Engineering, vol. Advances in Artificial Neural Systems, vol. Simulation of the Transportation System as a key for Productivity in a mm fab. Proceedings of the 14th European advanced process control and manufacturing apc m conference, Rome, Italy, April Automatisierungstechnik at , Vol.

Tagungsband Ambient Assisted Living, 6. ADLs erkennen und individualisieren. Detect and Individualize ADLs. Future Fab International, Issue 41, From Decompositional Physics to Compositional Information. Jahrgang B, Oldenbourg Industrieverlag, S. Advanced Engineering Informatics 25 , Nr. Proceedings of the 1st international congress on eMaintenance, Lulea, Sweden, June Overview and generic model.

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