bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiresolution schemes for an extended clarifier‐thickener model
Authors: Bürger Raimund , Ruiz Ricardo , Schneider Kai , Sepúlveda Mauricio 
Published: December 2008

AbstractA fully adaptive finite volume multiresolution scheme for one‐dimensional strongly degenerate parabolic equations with discontinuous flux modelling an extended clarifier‐thickener, is presented. The numerical scheme is based on a finite volume discretization using the approximation of Engquist‐Osher for the flux and explicit time stepping. Cell averages multiresolution scheme speeds up CPU time and memory requirements. A particular feature of our scheme is the storage of the multiresolution representation of the solution in a dynamic graded tree. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A semi‐adaptive split‐cosine scheme for the sine‐Gordon equation
Authors: Sheng Q. 
Published: December 2008

AbstractThis talk concerns the numerical solution of the nonlinear sine‐Gordon equation in rectangular large‐area Josephson junctions. An application of the adaptive method of lines leads to a system of second‐order nonlinear ordinary differential equations. The system is approximated by a nonlinear recurrence relation. Strang's splitting is then introduced for establishing a highly effective and stable semi‐adaptive scheme. The novel new method offers an efficient way in the solitary wave solution approximations. A stability analysis is presented. Straightforward numerical demonstrations on ring solitons up to higher time levels are given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stochastic oscillations in circuit simulation
Authors: Sickenberger Thorsten , Winkler Renate 
Published: December 2008

AbstractWe consider the simulation of noisy electronic circuits with oscillatory solutions. For their transient noise simulation we use variable step‐size two‐step schemes for stochastic differential‐algebraic equations. The performance of these methods in combination with a suitable step‐size control strategy is illustrated by an industrial test application. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of stress intensity factors in a plane homogeneous anisotropic solid
Authors: Steigemann Martin , Fulland Markus , Specovius‐Neugebauer Maria , Richard Hans A. 
Published: December 2008

AbstractThe accurate computation of stress intensity factors (SIFs) plays a decisive role in the determination of crack paths. The calculation of SIFs with the help of singular weight functions leads to pure Neumann problem for anisotropic elasticity in a plane domain with a crack. We present a method to overcome the specific numerical difficulties which arises while calculating these solutions with Finite Element methods. the accuracy and advantage of this method are shown by a numerical example, the calculation of SIFs of a compact tension specimen. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hopf bifurcations of travelling waves in a brake‐like system
Authors: Steindl Alois 
Published: December 2008

AbstractWe consider a system composed of an elastic tube, which is fixed at the outer boundary and in frictional contact with a rigid cylinder, rotating inside the tube about the common axis. Under the assumption of Coulomb's friction law at the contact surface between the two bodies several types of rotating slip‐stick and also slip‐stick‐separation travelling waves with different wave numbers can be observed.For a wide range of parameters the linearized system has unstable complex eigenvalues, which cause high frequency oscillations and unpleasant squeal. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stick‐slip‐separation waves in a rotating shaft‐bush system
Authors: Teufel Andreas , Troger Hans 
Published: December 2008

AbstractWe consider an elastic annular bush fitted to a rigid rotating shaft with a diameter mismatch. The formation of stick‐slip, slip‐separation and stick‐slip‐separation waves due to dynamic friction acting between the bush and the shaft is studied. Numerically, we calculate the loci of non‐smooth bifurcations in the parameter space for rotating mode‐1 waves on the shaft‐bush interface, varying the angular velocity and the static coefficient of friction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Upscaling in nonlinear thermal diffusion problems
Authors: Timofte Claudia 
Published: December 2008

AbstractThe aim of this paper is to study the homogenization of a nonlinear problem arising in the modelling of thermal diffusion in a two‐component composite. We consider, at the microscale, a periodic structure formed by two materials with different thermal properties. We assume that we have nonlinear sources and that at the interface between our two materials the flux is continuous and depends in a nonlinear way on the jump of the temperature field. We shall be interested in describing the asymptotic behavior, as the small parameter which characterizes the sizes of our two regions tends to zero, of the temperature field in the periodic composite. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Algorithm and MATLAB package for some nonlinear 2D evolution equations
Authors: Trif Damian 
Published: December 2008

AbstractWe will present LiScM2, a MATLAB package for numerical solutions of some partial differential evolution equations of the form ut + Lu = N (u, ∇u), with boundary and initial conditions, where L is a 2D linear elliptic operator (Laplace operator for this version) and N is a nonlinear part. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regularized Kalman filtering in dynamic SPECT
Authors: Celler A. , Qranfal J. , Trummer M.R. 
Published: December 2008

AbstractThis paper presents an algorithm for reconstructing a dynamic SPECT image. Projections of a time‐dependent activity are acquired in discrete time frames. This leads to a highly underdetermined set of equations for the images corresponding to each time frame. We reconstruct these images using a Kalman filter algorithm which helps is processing the time‐varying information, To obtain meaningful results a positivity constraint must be enforced. Due to the ill‐posedness of the problem, regularization is required. We compared Tikhonov and total bounded variation regularization schemes, and found the latter to be more effective, producing superior results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
About weak resolvability of initial‐boundary value problem for Foight model of liquid motion in domain with time‐dependent boundary
Authors: Turbin Mikhail V. , Zvyagin Victor G. 
Published: December 2008

AbstractWe prove the existence and uniqueness of a weak solution of the initial‐boundary value problem for the Foight model of liquid motion in a domain with time‐dependent boundary. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High order upwind scheme for modelling turbulent shallow water flow in hydraulic structures
Authors: Vázquez‐Cendón María‐Elena , Cea Luis 
Published: December 2008

AbstractAn unstructured finite volume model for quasi‐2D free surface flow with wet‐dry fronts and turbulence modelling is presented. The convective flux is discretised with either a an hybrid second‐order/first‐order scheme, or a fully second order scheme, both of them upwind Godunov's schemes based on Roe's average. The hybrid scheme uses a second order discretisation for the two unit discharge components, whilst keeping a first order discretisation for the water depth [2]. In such a way the numerical diffusion is much reduced, without a significant reduction on the numerical stability of the scheme, obtaining in such a way accurate and stable results. It is important to keep the numerical diffusion to a minimum level without loss of numerical stability, specially when modelling turbulent flows, because the numerical diffusion may interfere with the real turbulent diffusion.In order to avoid spurious oscillations of the free surface when the bathymetry is irregular, an upwind discretisation of the bed slope source term [4] with second order corrections is used [2]. In this way a fully second order scheme which gives an exact balance between convective flux and bed slope in the hydrostatic case is obtained. The k – ε equations are solved with either an hybrid or a second order scheme.In all the numerical simulations the importance of using a second order upwind spatial discretisation has been checked [1]. A first order scheme may give rather good predictions for the water depth, but it introduces too much numerical diffusion and therefore, it excessively smooths the velocity profiles. This is specially important when comparing different turbulence models, since the numerical diffusion introduced by a first order upwind scheme may be of the same order of magnitude as the turbulent diffusion. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Combinatorial preconditioners for scalar elliptic finite‐element problems
Authors: Avron Haim , Chen Doron , Shklarski Gil , Toledo Sivan 
Published: December 2008

AbstractWe present a new preconditioner for linear systems arising from finite‐elements discretizations of scalar elliptic partial differential equations. The solver is based on building a symmetric diagonally dominant (SDD) approximation of the stiffness matrix K. The approximation is built by approximating each element inside the collection {Ke } of element matrices by an SDD matrix Le. The SDD approximation L is built by assembling the collection {Le }. We then sparsify L using a graph algorithm, and use the sparsified matrix as a preconditioner. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laminar separation bubbles from a high Reynolds‐number asymptotic point of view
Authors: Braun Stefan 
Published: December 2008

AbstractClassical boundary layer theory proved to lose its validity if flow separation is encountered. However, introduction of the triple deck concept – i.e. allowing for the displacement effect of the viscous boundary layer to interact locally with the induced pressure (disturbances) in the outer inviscid flow regime – led to a successful description of ‘short’ laminar separation bubbles in various fundamental flow problems. Here we want to focus on situations which share the following distinctive feature: two‐dimensional steady state solutions of the underlying interaction equations exist in a limited range of values of a parameter controlling the conditions leading to separation only. Furthermore, these solutions turn out to be non‐unique in the vicinity of the limiting critical value of this parameter. Typical examples include leading edge separation, smooth backward facing step flow, channel flow with suction (cases of so‐called marginal separation) and subsonic expansion ramp flow, asymmetric trailing edge separation (classical triple deck flows). More recent investigations which take into account (local) unsteady, three‐dimensional and flow control device effects and concentrate on near critical flows indicate that (i) exceeding the critical value of the controlling parameter is associated with self‐sustained vortex shedding (time periodic bubble ‘bursting’ even in the absence of external disturbances), (ii) coherent structure formation caused by bubble bursting events turns out to be essentially self‐similar, (iii) the high sensitivity of the separated flow region with respect to external disturbances allows for effective application of (optimized) flow control devices in order to force or delay the transition process to turbulent boundary layer flow. The aim of the presentation is to deliver insight into the power of modern asymptotic analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic analysis of porous materials: Numerical simulation with an adaptive space‐time FEM
Authors: Chen Z. , Diebels S. , Steeb H. 
Published: December 2008

AbstractWe investigated a space‐time Galerkin method applied to the dynamic analysis of fully‐saturated porous material. The governing set of equations are derived from the well‐studied Theory of Porous Media (TPM). The numerical scheme consists of a coupled finite element discretization in the space‐time domain. Discontinuous approximations of the primary variables in time are employed. A natural flux treatment is applied in time to impose the consistency between the adjacent time intervals. A simple space‐time decoupled adaptive strategy based on the “jumps” in time and the ZZ error indicator in space is investigated. Numerical experiments demonstrate the efficiency and reliability of the proposed approach. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical analysis of chip formation during machining for different value of failure strain
Authors: Chodor Jaroslaw , Kukielka Leon 
Published: December 2008

AbstractGrinding is a very complicated processing. To increase quality of product and minimize the cost of abrasive machining, we should know physical phenomena which exist during the process. The first step to solution of this problem is analysis of machining process with a single abrasive grain. In the papers [1, 2] the thermo‐mechanical models of this process are presented, but in this work attention is concentrated on chip formation and his separation from object. The influence of failure strain εf on states of strain and stress in surface layer during machining is explained. The phenomena on a typical incremental step were described using step‐by‐step incremental procedure, with updated Lagrangian formulation. Then, the Finite Element Method (FEM) and Dynamic Explicit Method (DEM) were used to obtain the solution. Application was developed in the ANSYS system, which makes possible a complex time analysis of the physical phenomena: states of displacements, strains and stress. Numerical computations of the strain have been conducted with the use of two methodologies. The first one requires an introduction of boundary conditions for displacements in the contact area determined in modeling investigation, while the second – a proper definition of the contact zone through the introduction of finite elements of TARGET and CONTACT types, without the necessity to introduce boundary conditions. This model includes variational equations of the object's motion and deformation. Examples of calculations for the displacement, strain and stress field in the surface layer zones were presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weak coupling in function space: a unifying coupling approach for multiscale simulations
Authors: Fackeldey Konstantin , Krause Rolf 
Published: December 2008

AbstractIn multiscale simulations, often on the micro‐ and the macro scale different discretization are used in order to capture the different behavior of the materials under consideration on the respective scales. Using, e.g., molecular dynamics (MD) on the micro scale and finite elements (FE) in the macro scale, values in the phase space ℝd (MD) have to be correlated with the values from the FE‐simulation in the Sobolev space H1. Here, we present a new coupling approach which gives rise to a stabilizing new scale transfer operator. Our construction allows moreover for a unifying theoretical description of already existing coupling methods. The key idea is to construct the transfer operator by assigning a partition of unity to the molecular degrees of freedom, thus giving rise to a fully function space based treatment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Robust controllability of linear systems: Analysis and application to pursuit problems
Authors: Glizer Valery Y. , Turetsky Vladimir 
Published: December 2008

AbstractRobust controllability conditions for a linear uncertain system are derived. A class of transferring strategies is obtained. A robust controllability set, respecting a given control constraint, is constructed. An application example is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On phenomenological and micro‐mechanical models in finite elasticity and viscoelasticity for rubber‐like materials
Authors: Hossain Mokarram , Denzer Ralf , Possart Gunnar , Steinmann Paul 
Published: December 2008

AbstractThe structure of rubber‐like materials is characterised through chain‐like macromolecules which are linked together at certain points. This special structure leads to a completely random three‐dimensional network [5]. There are several phenomenological based models and micro‐mechanically motivated network models for elastic and viscoelastic polymeric materials which have been proposed in the literature [4]. The aim of the research work is to give an overview of various phenomenological and micro‐mechanical models for elastic and viscoelastic processes at large deformations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solution of industrial CFD problems with structured Boltzmann approach
Authors: Ibraghimova Elena 
Published: December 2008

AbstractA new algorithm and acorresponding software package are developed that contain a fast tensor algorithm for the deterministic solution of the Boltzmann equation. The domain space discretisation performed with the Delaunay grid and the velocity space discretisation is performed with the tensor grid, and benefits with multilinear decomposition. This algorithm is also implemented for GPGPU processors, which allows to reach very high computational performance. The memory and complexity requirements are comparable with most Navier‐Stockes solvers, however we solve the Boltzmann equation with chemical reactions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear vibrations of a ropeway system with moving passenger cabins
Authors: Knawa Marta , Bryja Danuta 
Published: December 2008

AbstractThe dynamic continuous model of a carrying rope for circulating bicable aerial ropeway is formulated. To describe nonlinear in‐plane vibrations excited by moving masses of passenger cabins a closed form model with Green‐Lagrange deformation is developed. The equations of motion of the system are derived on the basis of Lagrange equations with Ritz approximation of cable displacements applied. Numerical example of linear and nonlinear cable vibrations is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exact first and second derivatives by automatic differentiation
Authors: Naumann Uwe 
Published: December 2008

AbstractAutomatic differentiation (AD) is a method for computing derivatives of outputs of numerical programs with respect to its inputs both accurately (with machine precision) and efficiently. The two basic modes of AD – forward and reverse – and combinations thereof yield products of a vector with the Jacobian, its transposed, or the Hessian, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modellierung der Schwingungen beim Werkzeugschleifen
Authors: Panning L. , Kröger M. 
Published: December 2008

AbstractDie Fertigung von Bohrern und Schaftfräsern aus Hartmetall oder Schnellarbeitsstahl (HSS) erfolgt aufgrund der großen Härte der Werkstücke häufig durch Profilschleifprozesse mit Diamant‐ oder CBN‐Schleifscheiben. Aufgrund der Wechselwirkung zwischen Werkstück, Schleifscheibe und Prozess kommt es während der Erzeugung der Spannuten zu Werkstückschwingungen, die zu unerwünschten Fertigungsungenauigkeiten und Formfehlern führen. Ziel ist es, mit Hilfe von Simulationen kritische Prozessparameter zu ermitteln, bei denen z.B. durch regeneratives Rattern instabile Zustände auftreten. Diese können die Werkstückqualität erheblich reduzieren. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotics for some vibro‐impact problems with a linear dissipation term
Authors: Cabot Alexandre , Paoli Laetitia 
Published: December 2008

AbstractWe consider a mechanical system with a finite number of degrees of freedom submitted to a non smooth potential Φ and a viscous dissipation force. We study the asymptotic behavior of dissipative solutions when the time variable tends to +∞. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bridged interface cracks under transient thermal loading
Authors: Perelmuter Mikhail 
Published: December 2008

AbstractThe direct boundary element method is used to analyze of the stress‐strain state and fracture parameters of fiber‐reinforced layered composites structures with interface bridged cracks under transient thermal and mechanical loadings. It is supposed that unbroken fibers make up bridged zone along of whole or part of a delamination region between layers of composite materials. For modeling purposes the bridged zone is considered as a part of the interface crack between of joined materials and supposed that distributed nonlinear spring‐like bonds link and constrain the crack surfaces. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive time series filters to smooth and forecast economic variables
Authors: Pervukhina Elena , Emmenegger Jean‐François 
Published: December 2008

AbstractFour monthly Ukrainian trucking industry time series are investigated within period of January 2003 to February 2007. The AR(1) models are used to filter and predict real values of the series. The problems are solved on the basis of a differentiable matrix functional, defined on the coefficient matrix of the filter. The functional presents an information measure of the distribution parameters of the vector state and its tentative estimations and is well known as Kullback information divergence. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On kinematics of a parallel robot used for the minimally invasive surgery
Authors: Plitea N. , Pisla D. , Vaida C. 
Published: December 2008

AbstractOne of the pioneer fields for robots is their assimilation in surgery, especially in minimally invasive procedures. The paper presents the kinematics of an innovative parallel structure for the manipulation of surgical instruments in minimally invasive surgery. The parallel architecture has been chosen for its superiority in precision, repeatability, stiffness, higher speeds and occupied volume. The equations, which model the kinematics are pointed out for this robot based on its mathematically determined functional parameters. The results of the kinematical modeling are systematically presented and lead to the facile solving of the parallel structure. Some simulation results have been presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deconvolving blood‐alcohol concentration and alcohol beverage consumption from sensor measurements of transdermal alcohol
Authors: Dumett M.A. , Piterbarg Y. , Rosen I.G. , Schumitzky A. 
Published: December 2008

AbstractWe utilize mathematical, statistical and deconvolution techniques to estimate blood alcohol concentration and alcohol ingestion rate from vapor alcohol measurements coming from a new electro‐chemical transdermal alcohol bio‐sensor. A protocol suggesting how this can be done and a theoretical framework for the convergence of the method are also shown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anwendung eines Schmerzsensors
Authors: Schiefer F. , Ostermeyer G.‐P. 
Published: December 2008

AbstractDie Erforschung von Schmerz aus technischer Sicht ist ein bisher wenig behandeltes Forschungsgebiet. Ein erster Ansatz zur Problembeschreibung ist in [1] gegeben. Die Grundlage zur Anwendung eines Technischen Schmerzsensors ist ein Sensorkonzept zur technischen Schmerzdetektierung [2,3], mit dessen Hilfe ein Energieeintrag gemessen wird, der als ein Schmerzmaß für technische Systeme infolge periodischer und stoßartiger mechanischer Beanspruchungen interpretiert werden kann. Dieses Technische Schmerzmaß enthält implizit u. a. frequenzselektive Informationen über das Zeitverhalten des Energieeintrages sowie über die Ruckbeanspruchung dynamischer Systeme. Erste Anwendungen sind ein Stoßexperiment und die Trajektorienoptimierung eines Demonstrators, der bspw. ein Laufmaschinenbein repräsentieren kann. Zeit‐ und energieoptimale Trajektorien werden mit schmerzoptimierten Trajektorien verglichen. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)