bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dimension reduction in multiobjective optimization
Authors: Costa Lino , Oliveira Pedro 
Published: October 2008

AbstractIn multiobjective optimization there is often the problem of the existence of a large number of objectives. For more than two objectives there is a difficulty with the representation and visualization of the solutions in the objective space. Therefore, it is not clear for the decision maker the trade‐off between the different alternative solutions. Thus, this creates enormous difficulties when choosing a solution from the Pareto‐optimal set and constitutes a central question in the process of decision making. Based on statistical methods as Principle Component Analysis and Cluster Analysis, the problem of reduction of the number of objectives is addressed. Several test examples with different number of objectives have been studied in order to evaluate the process of decision making through these methods. Preliminary results indicate that this statistical approach can be a valuable tool on decision making in multiobjective optimization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aircraft wake vortices – prediction and mitigation
Authors: Holzäpfel Frank , Gerz Thomas , Baumann Robert 
Published: October 2008

AbstractThe current abstract presents selected topics investigated within the wake‐vortex research program of DLR. Two approaches are addressed that both aim at increasing airport capacity without compromising safety. One approach is to directly alleviate wake vortex strength and stability by constructive measures at the aircraft wings. The other approach utilizes the dominant influence of meteorological parameters like turbulence, wind shear, and temperature stratification on wake vortex fate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preconditioners for solving the indefinite linear system for higher order H (curl) discretisations
Authors: Ledger Paul David 
Published: October 2008

AbstractThis paper presents numerical results for a preconditioning technique for the iterative solution of the indefinite linear system of equations obtained when a higher order H (curl) conforming finite element approximation is adopted for the vector wave equation. Numerical results are presented for a model problem that includes a singularity at the origin and dicretisations that include graded meshes and uniform p. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New methods in fluid‐structure coupling with application to biomechanics
Authors: Cottet Georges‐Henri , Maitre Emmanuel , Milcent Thomas 
Published: October 2008

AbstractAn Eulerian approach is presented for generic fluid‐structure coupling of an elastic body with an incompressible fluid. We consider the coupling as a multiphysics problem where fluid‐solid interfaces are captured by a level‐set method. The main features of the method are its simplicity, and its natural control of mass and energy. We are indeed able to prove an energy equation which ensures in particular that the regularization of the force does not involve any energy dissipation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic positioning of a floating structure
Authors: Pick Marc‐André , Kreuzer Edwin , Wagner Jörg 
Published: October 2008

AbstractIn order to test numerical models describing the dynamics of a wave excited vessel a laboratory model setup for investigating roll motions at zero or small forward speeds was designed. A position and attitude measurement system consisting of an inertial measurement unit and a stereo–camera using an extended Kalman–filter was developed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Steady flow in the Willis circle using a Quemada model
Authors: Postelnicu Adrian , Florea Olivia , Pecurariu Cristian Falup 
Published: October 2008

AbstractThe paper presents new results on the dynamics of blood flow in the Willis circle, by taking into account the non‐Newtonian nature of the blood through a Quemada model. In previous papers we performed a steady analysis of the blood flow in the Willis polygon, by considering the blood as a Newtonian fluid. In hemodynamics this is the first step, while taking into account the non‐Newtonian behaviour of the fluid is called a second order approach. This is in fact the aim of our paper, to compare the results (blood flow rates and pressures) obtained in a non‐Newtonian approach with those furnished by a Newtonian modeling of the blood. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simultaneous reconstruction and segmentation for tomography data
Authors: Ramlau Ronny , Klann Esther , Ring Wolfgang 
Published: October 2008

AbstractWe present a Mumford‐Shah like approach for the inversion of CT and SPECT‐data (Single Photon Emission Computerized Tomography). With this approach we aim at the simultaneous reconstruction and segmentation of activity and density distribution from given tomography data. We assume the functions to be piecewise constant with respect to a set of contours. Shape sensitivity analysis is used to find a descent direction for the cost functional which leads to an update formula for the contour in a level set framework. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational models for the numerical simulation of voltage operated channels in nano–bio–electronics
Authors: Longaretti Massimo , Jerome Joseph W. , Sacco Riccardo , Chini Bice 
Published: October 2008

AbstractIn this article, we discuss the use of computational models in the study of voltage operated channels (VOCs) for bio‐electronic applications. Electrochemical and fluid–mechanical ionic transport are described through the coupled use of systems of partial and ordinary differential equations (PDEs and ODEs). Functional iteration techniques for system decoupling and mixed–hybridized finite element discretization methods are proposed and validated in the simulation of realistic problems in Electrophysiology and Biochemistry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cooperative work in an e‐learning environments: the COMSON case
Authors: Bilotta Eleonora , Pantano Pietro , Talarico Valerio 
Published: October 2008

AbstractCoupled Multiscale Simulation and Optimization in Nanoelectronics project isaMarie Curie RTN supported by the European Commission within the 6th Framework Research Programme of the EU. The COMSON project is run by a Consortium whose multiple aims are: to build an experimental software Demonstrator Platform (DP) for coupled simulation of devices, interconnects, circuits, EM fields and thermal effects (one single framework for simulation tool, optimisation in compound design space); to provide an e‐learning platform to be used as an inter and extra consortium transfer of knowledge (ToK) infrastructure; to provide a collaborative virtual work environment (CWE) to be used both for industrial activities and training. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Turbulent boundary layer on a plate with transpiration: Dynamical and thermal problems
Authors: Vigdorovich Igor 
Published: October 2008

AbstractScaling laws are established for the profiles of mean velocity and temperature, Reynolds‐stress components, turbulent heat flux and mean‐square temperature fluctuation, skin friction and wall heat transfer in the turbulent boundary layer on a flat plate with transpiration. In the case of blowing, the velocity and temperature distributions represented in scaling variables outside the viscous sublayer have universal forms known from experimental data for flow over an impermeable flat plate. The turbulent shearing stress and heat flux also can be represented in terms of these two functions. In the case of suction, the mean quantities are described by one‐parameter families of curves. Universal skin‐friction and heat‐transfer laws provide a basis for representation of the skin‐friction and heat‐flux distributions corresponding to different Reynolds numbers and transpiration velocities in terms of universal functions of one variable. The results are obtained without invoking any special closure hypotheses. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron energy level calculations for semiconductor nanostructures
Authors: Betcke Marta M. , Voss Heinrich 
Published: October 2008

AbstractAlthough self‐assembled quantum dots are grown on wetting layers, most simulations exclude the wetting layer. The neglected effects on the electronic structure of a pyramidal InAs quantum dot embedded in a GaAs matrix are investigated based on the effective one electronic band Hamiltonian, the energy and position dependent electron effective mass approximation, and a finite height hard‐wall 3D confinement potential. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Newtons coefficient of restitution at the macro‐ and nano‐scales
Authors: Weir Graham J. 
Published: October 2008

AbstractNewtons Coefficient of Restitution, for low velocity impacts between macroscopic rigid‐plastic identical spherical particles, depends primarily on the initial relative velocity, Youngs Modulus, particle size and the plastic yield stress. Surface tension becomes important for impacts between nano‐scale particles. The major implications of surface tension for impacts at the nano‐scale are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of asymmetric effects for shape memory alloys
Authors: Wilmanns Stefan , Mahnken Rolf 
Published: October 2008

AbstractExperimental results of shape memory alloys show a pronounced asymmetric behaviour between tension, compression and shear. For simulation of these effects in the constitutive equations different transformation strain tensors are introduced. These are related to the different variants for the multi‐variant‐ and detwinned‐martensite as a consequence of different stress states. In the framework of plasticity the concept of stress mode dependent weighting functions is applied in order to characterize the different stress states. Verification of the proposed methodology is succeeded for simulation of the pseudoelastic behaviour of shape memory alloys with different hardening characteristics in tension, compression and shear. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of flow of viscoelastic fluids
Authors: Wünsch Olaf , Krebs Mathias 
Published: October 2008

AbstractThe paper deals with the numerical calculation of highly viscous, non‐newtonian fluid flows in apparatus of mechanical engineering. We use a differential constitutive equation to approximate the real behaviour of technical fluids like polymer melts. By means of calculated flow examples in two and three dimensional geometries we demonstrate the influence of the non‐newtonian behaviour. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parameter analysis of the structure of matrix pencils by homotopic deviation theory
Authors: Ahmadnasab Morad , Chaitin‐Chatelin Françoise 
Published: October 2008

AbstractLet A, E ∈ ℂn ×n be two given matrices, where rank E = r < n. Matrix E is written in the form E = UVH where U, V ∈ ℂn ×r have rank r. 0 is an eigenvalue of E with algebraic (resp. geometric) multiplicity m (g = n – r ≤ m).We consider the pencil Pz = (A – zI) + tE, defined for t ∈ ℂ and depending on the complex parameter z ∈ ℂ. We analyze how its structure [8] evolves as the parameter z varies, by means of conceptual tools borrowed from Homotopic Deviation theory [1, 3]. As an example with z = 0, the structure of the pencil A + tE is determined by Homotopic Deviation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crack propagation calculation using trial cracks
Authors: Bäker Martin 
Published: October 2008

AbstractWe present a method to perform finite element calculations for crack propagation problems with arbitrary crack directions in two dimensions. The crack direction (angle of propagation) is determined by inserting small “trial cracks” at the crack tip. For each trial crack, the domain is remeshed to allow crack propagation between elements. The trial cracks are then opened and the energy release rate is measured. The optimum crack direction (i.e., the crack direction with maximum energy release) is determined by an optimisation procedure. Although the method is computationally expensive due to the need to perform several calculations for each crack increment, it has the advantage that the energy release rate can be calculated even in cases where other methods fail. After explaining the method, it is applied to some test examples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parametrization for mesoscale ocean transport through random flow models
Authors: Baydil Banu , Kramer Peter R. , Smith Shafer 
Published: October 2008

AbstractWe describe a mathematical approach based on homogenization theory toward representing the effects of mesoscale coherent structures on large‐scale transport in the ocean. We demonstrate the approach on a deterministic and a random model flow. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse problem in seismic imaging
Authors: Cameron Maria , Fomel Sergey , Sethian James 
Published: October 2008

AbstractWe address the problem of estimating sound speeds (seismic velocities) inside the earth which is necessary for obtaining seismic images in regular Cartesian coordinates. The main goals are to develop algorithms to convert time migration velocities to true seismic velocities, and to convert time‐migrated images to depth images in regular Cartesian coordinates.Our main results are three‐fold. First, we establish a theoretical relation between the seismic velocities and the time migration velocities using the paraxial ray tracing theory. Second, we formulate an appropriate inverse problem describing the relation between time migration velocities and depth velocities and show that this problem is mathematically ill‐posed, i.e., unstable to small perturbations. Third, we develop numerical algorithms to solve regularized versions of these equations which can be used to recover smoothed velocity variations. Our algorithms consist of efficient time‐to‐depth conversion algorithms based on Dijkstra‐like Fast Marching Methods, as well as level set and ray tracing algorithms for transforming Dix velocities into seismic velocities. Our algorithms are applied to both two‐dimensional and three‐dimensional problems and we test them on a collection of both synthetic examples and field data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear modal interactions and low order modeling of a kicked flexible rod
Authors: Cusumano Joseph P. 
Published: October 2008

AbstractA magnetically kicked flexible‐beam oscillator is studied experimentally. Spectral bifurcation diagrams of the attracting steady states are obtained, and the system is seen to exhibit periodic, quasiperiodic and chaotic responses. The proper orthogonal decomposition (POD) is applied to spatial strain gauge data, and a specific nonlinear two‐mode interaction is shown to be present in all responses. Based on these experimental observations, a two degree of freedom piecewise linear autonomous model is developed, which captures much of the behavior observed in the experiments. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive high‐resolution simulation of realistic gaseous detonation waves
Authors: Deiterding Ralf 
Published: October 2008

AbstractThe numerical approximation of detonation waves in gaseous combustible mixtures is extremely demanding since a wide range of scales needs to be resolved. A dynamically adaptive high‐resolution finite volume method is described that has enabled accurately resolved computational investigations of the transient behavior of regularly oscillating detonations in lowpressure hydrogen‐oxygen mixtures in realistic two‐dimensional geometry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A level set method for 3D low frequency electromagnetic imaging with applications in geophysical prospecting
Authors: Dorn Oliver , Villegas Rossmary 
Published: October 2008

AbstractWe propose a novel shape reconstruction technique for controlled source 3D low frequency electromagnetic induction tomography which uses a level set representation of the shapes. The main application which we have in mind in this paper is geophysical prospecting, in particular the monitoring of reservoir flooding processes in secondary oil recovery and the investigation of conductive geophysical structures at a depth of up to a few hundred metres. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive algorithms for phase field models of some interface problems
Authors: Du Qiang 
Published: October 2008

AbstractWe present our on‐going works with current and former colleagues at Penn State (L.Q. Chen, W.M. Feng, S. Hu, Z.K. Liu, P. Yu, X. Wang and J. Zhang) on the numerical algorithms for the phase field simulations of some interface problems, ranging from microstructure evolution in multicomponent alloy to multicomponent lipid vesicles. We discuss recent development of highly adaptive computational algorithms for large scale phase field simulations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of the disposition of a P‐gp substrate in wild‐type and knockout mice tissues: Development of a physiologically based pharmacokinetic (PBPK) model and its global sensitivity analysis
Authors: Fenneteau F. , Li J. , Couture L. , Turgeon J. , Nekka F. 
Published: October 2008

AbstractIn order to improve understanding and prediction of drug disposition prior to in vivo experiments, we aimed to develop a PBPK model that accounts for the involvement of P‐glycoprotein activity and expression in mouse brain, liver, kidney and heart tissues. Model parameters of P‐gp activity and drug diffusion were mainly extrapolated from in vitro data. Model simulations, compared with tissue concentration of 3H‐domperidone intravenously administered toWT and KO mice, suggest the involvement of additional membrane transporters in heart and brain tissues. The global sensitivity analysis showed that the variability of model predictions is related to the variability of the unbound fraction to plasma protein, whereas the uncertainty of the model predictions is associated with the uncertainty of the parameters related to P‐gp genetic expression, and to the activity of additional transporters in heart and brain tissues. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the discrete element method to model cohesive materials
Authors: Gaugele Timo , Storchak Michael , Eberhard Peter 
Published: October 2008

AbstractIn this contribution we show how the discrete element method (DEM) can be applied to model cohesive materials which exhibit ductile behaviour by introducing connective elements that can bear a certain load. The modelled material is verified by simulating a orthogonal cutting process which is compared to experimental results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A computational framework of three dimensional configurational‐force‐driven crack propagation
Authors: Gürses Ercan , Miehe Christian 
Published: October 2008

AbstractA variational formulation of quasi‐static brittle fracture is considered and a new finite‐element‐based computational framework is developed for propagation of cracks in three‐dimensional bodies. We outline a consistent thermodynamical framework for crack propagation in elastic solids and show that the crack propagation direction associated with the classical Griffith criterion is identified by the material configurational force which maximizes the local dissipation at the crack front. The evolving crack discontinuity is realized by the doubling of critical nodes and triangular interface facets of the tetrahedral mesh. The crucial step for the success of the procedure is its embedding into an r‐adaptive crack‐facet reorientation procedure based on configurational‐force‐based indicators in conjunction with crack front constraints. We further propose a staggered algorithm which minimizes the stored energy at frozen crack state followed by the successive crack releases at frozen deformation. This constitutes a sequence of positive definite subproblems with successively decreasing overall stiffness, providing a very robust algorithmic setting in the postcritical range. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the modeling of thermo‐electro‐magneto‐mechanical solids at finite strains
Authors: Kiefer Björn , Rosato Daniele , Miehe Christian 
Published: October 2008

AbstractA short overview of the mechanics of electromagnetic continua at finite strains is provided in this paper. In this framework objective thermodynamically‐consistent constitutive relations are formulated for materials that exhibit thermo‐electro‐magnetomechanical coupling. In particular a model for an isotropic hyperelastic magnetic solid is considered, which finds application for magnetorheological elastomers (MRE). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal control for supply network models: adjoint calculus
Authors: Göttlich Simone , Herty Michael , Kirchner Claus 
Published: October 2008

AbstractWe consider a PDE based supply network model with controllable nodes for which we derive an optimal control problem and present an adjoint‐based solution technique. The supply network has two basic building blocks: The dynamics in a supplier is governed by a PDE and the behavior inside a queue is described by an ODE. The network model provides a framework to couple these equations at nodes. We introduce controls at so‐called dispersing nodes and discuss suitable cost functionals leading to optimal control problems which we solve by a projected gradient method. The gradient information can be obtained from adjoint equations which we derive in the context of our supply network model. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automatic differentiation in meteorology and oceanography
Authors: Korn Peter 
Published: October 2008

AbstractThe physically consistent integration of observational data in dynamical circulation models of the atmosphere/ocean, e.g. for the purpose of predicting the future evolution of the climate system relies on variational data assimilation algorithms. These algorithms are based on the adjoint method of optimal control theory and implemented by Automatic Differentiation (AD) tools. The presence of turbulent phenomena imposes a challenge on AD based methods of adjoint flow control and highlights the role of the computational turbulence model. For the Lagrangian Averaged turbulence model, applied to the 3D Navier‐Stokes equations, we establish well‐posedness of the data assimilation problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and numerical investigations of crimped end fittings
Authors: Kreikemeier Janko , Gabbert Ulrich 
Published: October 2008

AbstractThe paper deals with numerical and experimental investigations of steel made hulls crimped onto glass fibre reinforced plastic rods. The aim is to optimize the crimping procedure to realize maximum pull out forces of the specimens. The numerical simulations were performed with the commercial FEA package ABAQUS. For the contact formulation a Coulomb friction law with a constant friction coefficient was applied. The damage and fracture states within the composite rods due to the crimping process were investigated by scanning electron microscopy. The results obtained were discussed and an outlook to further work is given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)