bluuebunny/crossref_metadata_2025_split huggingface dataset:
Voltage amplification transfer function analysis of the operational amplifier in the negative capacitance circuits for vibration control with piezoceramics
Authors: Oleskiewicz Robert , Neubauer Marcus , Krzyzynski Tomasz 
Published: August 2008

AbstractPiezo elements due to their ability of converting mechanical energy into electrical energy and vice versa can be found in numerous mechanical vibration damping and absorbing applications. A desired effect may be customized by an external impedance shunt branch connected to the plates of the piezo element. The negative capacitance connected in serial with the passive shunt significantly improves the damping and absorbing performance of such systems. Negative capacitance circuit is built of an impedance converter realized by the operational amplifier. Since the amplifiers are not the ideal elements, the performance of the proposed systems is limited. This is due to the maximum voltages and currents that the operational amplifiers are able to generate. This effect causes instabilities and limits the operational area of the impedance converter. In the paper, the amplification transfer function of the non‐ideal operational amplifier in the negative impedance converter is studied, and the necessary modification with the additional passive elements is proposed. The influence of the certain imperfections in the design, and its improvements are shown on the system consisting of the 1DOF mechanical oscillator, and a shunted piezo element. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strong tractability of multivariate integration of arbitrary order
Authors: Dick Josef , Pillichshammer Friedrich 
Published: August 2008

AbstractWe show the existence of digitally‐shifted polynomial lattice rules which achieve strong tractability results for Sobolev spaces of arbitrary high smoothness. The convergence rate is shown to be best possible up to a given degree of smoothness of the integrand. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic expansion of highly conductive thin sheets
Authors: Schmidt Kersten , Tordeux Sébastien 
Published: August 2008

AbstractSensitive measurement and control equipment are protected from disturbing electromagnetic fields by thin shielding sheets. Alternatively to discretisation of the sheets, the electromagnetic fields are modeled only in the surrounding of the layer taking them into account with the so called Generalised Impedance Boundary Conditions.We study the shielding effect by means of the model problem of a diffusion equation with additional dissipation in the curved thin sheet. We use the asymptotic expansion techniques to derive a limit problem, when the thickness of the sheet ε tends to zero, as well as the models for contribution to the solution of higher order in ε. These problems are posed in limit area of vanishing ε with condition for the jump of the solution and it's normal derivative, which avoid to mesh the computational domain, even locally, at the scale of ε.We derive the problems for arbitrary order and show their existence and uniqueness. Numerical experiments for the problems up to second order show the asymptotic convergence of the solution of right order in mean of the thickness parameter ε. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A hybrid coupling interface method for elliptic complex interface problems
Authors: Chern I‐Liang , Shu Yu‐Chen 
Published: August 2008

AbstractWe propose a coupling interface method (CIM) under Cartesian grid for solving elliptic complex interface problems in arbitrary d dimensions, where the coefficients, the source terms, and the solutions may be discontinuous or singular across the interfaces. It consists of a first‐order version (CIM1) and a second‐order version (CIM2). In one dimension, this finite difference method at a grid point adjacent to the interface is derived based on piecewise linear (CIM1) or quadratic (CIM2) approximation of the solution and two jump conditions. The method is extended to high dimensions through a dimensionby‐dimension approach. To connect information from each dimension, a coupled equation for the principal derivatives is derived through the jump conditions in each coordinate direction. For CIM2, one‐side interpolation for cross derivatives is need. This coupling approach reduces number of grid point in the finite difference stencil. The hybrid method uses CIM1 or CIM2 adaptly for complex interface. Numerical tests demonstrate that CIM1 and CIM2 are respectively first order and second order in the maximal norm with less error as compared with other methods. In addition, the hybrid CIM can solve complex interface problems in two and three dimensions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quadrature formulae with multiple nodes and a maximal trigonometric degree of exactness
Authors: Milovanović Gradimir V. , Cvetković Aleksandar S. , Stanić Marija P. 
Published: August 2008

AbstractIn this paper we consider interpolatory quadrature formulae with multiple nodes that have the maximal trigonometric degree of exactness. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical analysis of shear bands in solids by means of computational homogenization
Authors: Stanković L. , Mosler J. 
Published: August 2008

AbstractA novel fully three–dimensional framework for the numerical analysis of shear bands in solids undergoing large deformations is presented. The effect of micro shear bands on the macroscopic material response is computed by means of a homogenization strategy. More precisely, a strain–driven approach which complies well with displacement–driven finite element formulations is adopted. The proposed implementation is based on periodic boundary conditions for the micro–scale. Details about the implementation of the resulting constraints into a three–dimensional framework are discussed. The shear bands occurring at the micro–scale are modeled by a cohesive zone law, i.e., the tangential component of the traction vector governs the relative shear sliding displacement. This law is embedded into a Strong Discontinuity Approach (SDA). To account for realistic sliding modes, multiple shear bands are allowed to form and propagate in each finite element. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of a mean shear on the spectrum of passive scalar fluctuations
Authors: Celani A. , Cencini M. , Vergassola M. , Villermaux E. , Vincenzi D. 
Published: August 2008

AbstractThe form of the spectrum of passive scalar fluctuations in the inertial–convective range is investigated. In the presence of a mean shear, there exists a critical wave number kc. At wave numbers greater than kc, the mean shear does not influence the spectrum of scalar fluctuations and the Obukhov–Corrsin prediction holds. At wave numbers smaller than kc, the mean shear dominates and the spectrum is less steep. These predictions are based on the study of Lagrangian dynamics of fluid particles and account for the experimental observations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dissipative solitons and their interactions
Authors: Akhmediev N. , Soto‐Crespo J. M. , Grelu Ph. 
Published: August 2008

AbstractCoupled soliton pairs in nonlinear dissipative systems can exist in various forms. They can be stationary, or they can pulsate periodically, quasi‐periodically or chaotically, as is the case for single solitons. Each type is stable in the sense that a given bound state exists in the same form inde.nitely. Single solitons can be perfectly stable for a given set of parameters. However, this does not mean that a bound state formed from them is either stationary or stable. Moreover, their relations can be highly complicated. Such is the life of dissipative solitons. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conditional Lagrange derivative and its application
Authors: Béda Peter B. , Béda Gyula 
Published: August 2008

AbstractOur paper aims to show what to do in material modeling for an inelastic body. The method we use is based on the virtual work σ ′δε and on the variation of some function W with respect to the strain tensor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic analysis of porous materials: Numerical modeling with a space‐time FEM
Authors: Chen Z. , Steeb H. , Diebels S. 
Published: August 2008

AbstractIn the current work, we investigate the dynamic analysis of a two‐phase porous material using the space‐time discontinuous Galerkin method. The physical model is based on the Theory of Porous Media (TPM). The finite element approximation consists of continuous approximations in space but discontinuous ones in time. The continuity condition between the adjacent time intervals is weakly enforced by the upwind flux treatment. No artificial penalty function is involved. Moreover, the Embedded Velocity Integration technique is applied to reduce the second‐order equation in time into a first order one without introducing an additional constraint. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A sequential Monte Carlo algorithm for solving BSDEs
Authors: Gobet Emmanuel , Labart Céline 
Published: August 2008

AbstractWe present and analyze a numerical algorithm for solving BSDEs based on Picard iterations and on a sequential control variate method. Its convergence is geometric. Moreover, our algorithm provides a regular solution w.r.t. time and space. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modified Landweber tterations in a multilevel setting applied to the determination of nonlinear material parameters in piezoelectricity
Authors: Lahmer Tom 
Published: August 2008

AbstractAn efficient solution of the inverse problem of identifying nonlinear dependencies in hyperbolic systems of PDEs, here piezoelectric material parameter curves, is the aim of this work. The dominant material tensor entries in the coupled field equations which describe the electromechanical interplay are approximated by functions depending on the physical field quantities electric field or mechanical stress. In order to solve this nonlinear and ill‐posed problem of parameter curve identification efficiently, modified Landweber iterations (steepest descent and minimal error) will be studied. A multilevel approach is expedient due to the discretization of the unknown parameter curves and high computational efforts solving the forward problem (transient, nonlinear FEM computations). Theoretical investigations concerning convergence and regularization properties of the methods in a multilevel scenario will be presented, along with numerical results from an example in piezoelectricity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A note on the error growth in the numerical integration of periodic orbits
Authors: Calvo M. , Laburta M.P. , Montijano J.I. , Rández L. 
Published: August 2008

AbstractThe aim of this note is to extend the analysis of B. Cano and J. M. Sanz‐Serna [2] on the global error behaviour of general one step methods in the numerical integration of a periodic orbit to the case that such a periodic orbit can be embedded into a family of periodic orbits. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automatic differentiation for portable process systems models
Authors: Petera Monika 
Published: August 2008

AbstractThe development of complicated mathematical models in process systems engineering requires a lot of human effort. The high development cost of complex models can be reduced by reusing submodels created by other modelers. The exchange of ready‐to‐use components requires a common standardized data format. CapeML is an XML‐based meta language defined for describing equation‐based models in process system engineering. This domain specific language provides a convenient level of abstraction to which auxiliary code transformations can be applied. Automatic differentiation is a semantic transformation of programs that describe mathematical functions. It applies the chain rule of differential calculus and generates a new program that additionally calculates the derivatives of the underlying function. ADiCape is an XSLT‐based tool for automatic augmentation of CapeML models with the derivative information. A platform‐independent CapeML representation of a model together with additional code to calculate derivatives is available in a bundle and can be reused by the engineers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rate‐dependent incremental variational formulation of ferroelectricity
Authors: Rosato Daniele , Miehe Christian 
Published: August 2008

AbstractThe paper presents continuous and discrete variational formulations for the treatment of the non‐linear response of piezoceramics under electrical loading. The point of departure is a general internal variable formulation that determines the hysteretic response of the material as a generalized standard medium in terms of an energy storage and a rate–dependent dissipation function. Consistent with this type of standard dissipative continua, we develop an incremental variational formulation of the coupled electromechanical boundary value problem. We specify the variational formulation for a setting based on a smooth rate–dependent dissipation function which governs the hysteretic response. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaling limits of magnetic forces between two bodies
Authors: Schlömerkemper Anja , Schmidt Bernd 
Published: August 2008

AbstractWe report on a study of the magnetic force between two rigid bodies in the continuum limit starting from atomistic dipoledipole interactions for various micro‐ and macroscopic distance regimes, cf. [A. Schlömerkemper, B. Schmidt, Discrete‐tocontinuum limits of magnetic forces in dependence on the distance between bodies, MPI MIS Preprint 29, 2007]. For bodies that are far apart in atomic units classical formulae for magnetic forces are recovered, while for bodies whose distance is comparable to the atomistic lattice spacing a new term that explicitly depends on the atomistic distance and the underlying crystal lattice structure is obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐Reynolds boundary driven cavity flows in a thin liquid shell
Authors: Sznitman J. , Rösgen T. 
Published: August 2008

AbstractLow‐Reynolds recirculating cavity flows are traditionally generated from lid‐driven boundary motion at a solid‐fluid interface or result from shear flow over an opening. Such flows are typically described by the equations of creeping motion, where viscous forces are dominant. We illustrate using Particle Image Velocimetry (PIV) an original family of boundary‐driven cavity flows occurring, in contrast to classic configurations, at a liquid‐gas interface: thermally‐induced Marangoni flows in a thin liquid shell generate forced, steady‐state recirculating flows inside the cavity. Forcing relies on viscous mechanisms at the boundary but resulting flow patterns are, however, inviscid. Here, the inviscid equations of fluid motion are not used as an approximation, but rather come as a result from the solution of the creeping motion equations in the region inside the sphere. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new shallow water model, by asymptotic analysis, with linear dependence on depth
Authors: Rodríguez José M. , Taboada‐Vázquez Raquel 
Published: August 2008

AbstractIn this paper, we study Euler equations in a domain with small depth. With this aim, we introduce a small a‐dimensional parameter ε related to the depth and we use asymptotic analysis to study what happens when ε becomes small. In this way we obtain a shallow water model that considers the possibility of a non‐constant bottom and the horizontal velocity components depend on z if the vorticity is not zero. The new model is able to calculate exactly the solutions to Euler equations that are linear in z, whereas the classic model just obtains the average velocities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of reduced electric arc models
Authors: Torrilhon Manuel 
Published: August 2008

AbstractAn energy equation coupled to the eddy‐current Maxwell equations with nonlinear material coefficients gives a reduced electric arc model with interesting existence and stability behaviour. Applications are arcs in industrial plasma flows. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Learning multiresolution schemes for compression of images
Authors: Yáñez D. F. , Aràndiga F. , Cohen A. 
Published: August 2008

AbstractWe introduce a new type of multiresolution based on the Harten's framework using learning theory. This changes the point of view of the classical multiresolution analysis and it transforms an approximation problem in a learning problem opening great possibilities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Locomotion based on the control of the shape of magnetic fluid surfaces and of magnetizable media
Authors: Zimmermann K. , Naletova V.A. , Zeidis I. , Turkov V.A. , Böhm V. , Kolev E. , Popp J. 
Published: August 2008

AbstractThe realization of locomotion based on the deformation of a free surface of a magnetic fluid layer in a traveling magnetic field is studied. A plane flow of an incompressible viscous magnetic fluid layer on a horizontal surface in a nonuniform magnetic field and a plane two‐layers flow of incompressible viscous magnetic fluids between two parallel solid planes in a magnetic field is considered. Also the flow of an incompressible viscous magnetic fluid layer on a cylinder in a nonuniform magnetic field is an object of investigation. The deformation and the motion of a body made by a magnetizable polymer in an alternating magnetic field are experimentally studied. The cylindrical body (worm) which is located in a cylindrical tube is analyzed. These effects can be used in designing autonomous mobile robots without a hard cover. Such robots can be employed in clinical practice and biological investigations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exact equations for smoothed Wigner transforms and homogenization of wave propagation
Authors: Athanassoulis A. G. , Politis K. S. 
Published: August 2008

AbstractThe Wigner transform (WT) is a quadratic transform that takes an oscillatory function u (x): ℝn ↦ ℂd to a phase‐space density W (x, k) = W [u ](x, k): ℝ2n ↦ ℂd ×d , resolving it over an additional set of 'wavenumber' variables. The WT and its variations have been heavily used in quantum mechanics, semiconductors, homogenization of wave equations, timefrequency analysis, signal processing, pseudodifferential operators etc.The WT however has a fundamental difficulty: WTs exhibit artifacts, collectively known as ‘interference terms’, and can be arbitrarily more complicated than the original wavefunction. A very successful, well established way to go around this is using the Wigner measures (WMs), a semiclassical approximation to the WT. We propose a different approach, namely smoothing the WT with an appropriate kernel. Such smoothed WTs (SWTs) have been used with great success in signal processing. They have not been used in the treatment of PDEs, a fundamental obstacle being the lack of exact equations governing their evolution. We present the machinery which allows the coarse‐scale reformulation of a broad class of wave problems in terms of the SWT, along with numerical experiments which clearly show the validity and applicability of the method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetostrictive actuation of a smart beam with hysteretic material behaviour
Authors: Bossong Heiko , Schmidt Rüdiger 
Published: August 2008

AbstractMagnetostrictive materials can be used as actuators in smart structures technology. The relation between induced strain and the applied magnetic field is nonlinear and shows hysteretic behaviour. Thus the magnetomechanical coupling coefficient is not constant and should be defined as a function of strain or magnetic field in computations.In this study the hysteresis of a mechanically unconstrained actuator is determined using the Michelson interferometry. The hysteretic behaviour is modelled phenomenologically by a Preisach model. Using these experimental data for the modelling of an active structure with embedded magnetostrictive actuators, the actual coupling coefficient can be determined utilising the Preisach model. With this procedure the actuation strain of an embedded actuator, including the physical nonlinearities, can be calculated using the material characteristics obtained with an unconstrained actuator. For the determination of the actual coupling coefficient a strain‐ and field‐dependent approach is used.For an experimental validation of the method outlined above, a magnetostrictive actuator is characterised experimentally and then applied to a cantilever aluminium beam. Then, the tip displacement of the actuated beam is measured with a laser triangulation sensor and compared with the numerical results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of internal parametric and kinematic excitation on nonlinear gearbox vibration
Authors: Byrtus Miroslav , Zeman Vladimír 
Published: August 2008

AbstractThis paper deals with mathematical modelling of nonlinear vibration of large rotating shaft systems with gears and rollingelement bearings. Gearing and bearing couplings bring into the system nonlinear phenomena like impact motions due to the possibility of the mesh interruption. The motion of the system is influenced by the internal kinematic excitation in gearing and by the parametric excitation caused by periodic change of number of teeth in gear meshing. The influence of simultaneous internal kinematic and parametric excitation is investigated in dependence on revolutions of the driving shaft of a test‐gearbox. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
BepiColombo gravitational capture and the elliptic restricted three‐body problem
Authors: Campagnola Stefano , Lo Martin 
Published: August 2008

AbstractThis paper shows how the BepiColombo trajectory near Mercury follows the invariant manifolds to its final capture. The BepiColombo gravitational capture provides several recovery opportunities at nominal conditions and was designed by exploring the solution space entirely, without knowledge of the invariant manifolds. In this work we reproduced the trajectory in the model of the elliptic restricted three body‐ problem (due to the high eccentricity of Mercury's orbit) and showed that it does follow the manifolds. Consequently we envision that manifolds should be used to give insight on the solution space, speeding up the design and optimization process and there by saving cost. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximate implicitization and recursive surface intersection algorithms
Authors: Dokken Tor 
Published: August 2008

AbstractMost published work on intersection algorithms for Computer Aided Design (CAD) systems addresses transversal intersections [1], situations where the surface normals of the surfaces intersected are well separated along all intersection curves. For transversal intersections the divide and conquer strategy of recursive subdivision, Sinha's theorem [2] and the convex hull property of NonUniform Rational B‐Spline surfaces (NURBS) efficiently identify all intersection branches. However, in singular or near singular intersections, situations where the surfaces are parallel or near parallel in an intersection region, along an intersection curve or in an intersection point, even deep levels of subdivision will frequently not sort out the intersection topology. The paper will focus on the novel approach of Approximate Implicitization to address these challenges. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)