bluuebunny/crossref_metadata_2025 huggingface dataset:
Aufbau eines elastischen Mehrkörpermodells für die Flügelhinterkante von Transportflugzeugen
Authors: Winter Evelyn , Woernle Christoph , Heyden Thomas
Published: February 2009

Moderne Transportflugzeuge mit hohen Reisegeschwindigkeiten erfordern die Variation des Auftriebsbeiwerts mittels der Hochauftriebssysteme, um bei Start und Landung geringere Fluggeschwindigkeiten zu erzielen. Zu den Hochauftriebssystemen zählen die Vorflügel (Slats) an der Vorderkante und die Landeklappen (Flaps) an der Hinterkante des Flügels. Die modellierte Flügelhinterkante besteht aus zwei Landeklappen, welche auf insgesamt vier Tracks drehbar gelagert sind und durch Koppelgetriebe bewegt werden. Die äußere Landeklappe wird außerdem in einer Führungsschiene abgestützt. Der Antrieb erfolgt durch eine zentrale Antriebseinheit, ein Wellensystem und hoch untersetzende Getriebe. Die Landeklappen und einzelne Komponenten der Tracks werden flexibel als FE–Modell aufgebaut, da die eingeprägten Luftlasten zu signifikanten Verformungen führen. Die elastischen Körper werden in ein Mehrkörpermodell des Gesamtsystems implementiert, welches zusätzlich das als starr angenommene Wellensystem enthält. Die Luftlasten werden als Resultierende an der Klappenvorderkante aufgebracht, wobei der Versatz der Lastangriffspunkte durch Korrekturmomente berücksichtigt wird. Die Deformation des Flügels unter den Luftlasten wird als rheonome Bindung beschrieben. Hierdurch können Wechselwirkungen zwischen dem Landeklappensystem und den Flügelverformungen untersucht werden. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation der Dynamik des Vorflügelsystems von Transportflugzeugen mit Hilfe elastischer Mehrkörpermodelle
Authors: Zierath János , Woernle Christoph , Heyden Thomas
Published: February 2009

Bei Flugzeugen wird der Auftriebsbeiwert der Tragflächen in der Start– und Landephase durch Hochauftriebssysteme vergrößert, wodurch die Fluggeschwindigkeit reduziert werden kann. Zu den Hochauftriebssystemen zählen neben den Landeklappen (Flaps) auch die Vorflügel (Slats) an der Vorderkante des Flügels.

Das Vorflügelsystem besteht aus mehreren Vorflügelkörpern, die jeweils durch mindestens zwei in Rollen gelagerte Bogensegmente geführt werden. Die Bogensegmente sind als gebogene Zahnstangen ausgeführt, in welche durch ein Wellensystem angetriebene Ritzel eingreifen. Das Antriebssystem umfasst eine zentrale Antriebseinheit, ein Wellensystem und hoch untersetzende Getriebe. Für die Simulation des dynamischen Verhaltens unter Luftlasten wird ein elastisches Mehrkörpermodell aufgebaut. Die Vorflügelkörper unterliegen größeren Deformationen und werden mit Hilfe der Methode der Finiten Elemente elastisch modelliert. Die Rollenführungen der Bogensegmente werden durch kinematische Ketten beschrieben. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Visualization of Patient Specific Arterial Geometries Using the Virtual Histology
Authors: Brands Dominik , Klawonn Axel , Rheinbach Oliver , Schröder Jörg
Published: February 2009

The simulation of a balloon–angioplasty (clinical treatment of atherosclerotically degenerated arteries) requires information of the anatomical and physiological composition of the arterial wall. The intravascular ultrasound and the interpretation by a virtual histology provide cross–sectional images of the diseased arterial walls where the different components are characterized by color–coding. Using these information and the reconstruction of the vessel path from biplane angiography the patient specific data are visualized and discretized. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective parameters of cancellous bone
Authors: Ilic Sandra , Hackl Klaus , Gilbert Robert
Published: February 2009

Cancellous bone is a two–component structure consisting of the bone frame and interstitial blood marrow. In the scope of this presentation, the multiscale finite element method is used for its modeling. This method results from a combination of homogenization theory and the theory of finite elements and is based on the calculation of effective material parameters by investigating representative volume elements (RVEs). For the particular kind of material considered here, a cubic two–phase RVE is assumed where the dry skeleton is modeled in different ways. Apart from the variations of the geometry, the influence of the usage of different types of finite elements is studied in this context. Note that the presence of a liquid phase requires dynamic investigation including the viscous phenomena. To this end, acoustic excitation and an analysis in the complex domain are chosen. The method permits calculation of the effective material parameters such as Young's modulus, bulk modulus and Poisson's ratio and furthermore the simulation of the behaviour of the complete bone or of its parts. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control and stability of the complex inverted pendulum models in application to postural sway analysis of the vertical human stance
Authors: Kizilova Natalya
Published: February 2009

Mechanism of balance control is investigated on computerized posturography data on the vertical two–legged and one–legged stances measured on healthy subjects and the patients with osteohondrosis and coxarthrosis. Oscillations of the center of mass over 30 s of keeping the quiet stance and the trajectories for a step forward off the force platform have been computed. It was shown that during the one–legged stance the balance control strategy includes ‘scanning’ of the larger area with bigger sway amplitudes in the vicinity of the stable state as compared to the two–legged stance. A generalized model of the body as a multi–link system is proposed. Mass and inertia of each body segment and torques in joints are taken into consideration. The calculated own and forced frequencies of the model correspond to the spectral analysis of the posturography data. One–legged stance is proposed as a proper test for revealing the balance disorders. It is shown that investigation of the oscillations and trajectories of the center of mass for the step forward off the force platform is perspective for medical diagnostics to distinguish between the spine and joint pathologies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite Element Modelling of Bioactive Contact in Bone‐Implant Interface
Authors: Lutz André , Nackenhorst Udo
Published: February 2009

Finite element simulation for the prediction of bone remodelling caused by implants is a powerful method to improve or to rate implant designs even before they will be evaluated in clinical studies. But the bone–implant interaction is often modelled as ideal bonding in the interface. This approach is not suitable to describe the interrelation of both parts in a physiological manner. To correct these insufficiencies a 3D bioactive contact element has been developed. This contact element describes on the one hand the pure mechanical interaction and on the other hand the mechanical stimulated bone ingrowth in porous surfaces. The benefits of the use of the bioactive contact element regarding the standard method will be presented in this contribution. A comparison of both methods based on clinic results regarding a hip prosthesis with mixed surface textures will be shown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An atomic interaction‐based rod formulation for modelling Gecko adhesion
Authors: Sauer Roger A.
Published: February 2009

We present a nonlinear rod model which describes the adhesion mechanism used by the Gecko to cling to inclined and overhanging surfaces. The rod formulation is used to model the fine, hair–like setae, which form the microstructure of the Gecko toes. A simple geometric representation, based on hyperbolas, is used to capture the branching of the seta. The adhesion between seta and surface is modelled by an atomic interaction potential. The seta model is cast into a nonlinear finite element framework, which is used to simulate and study the pull–off behavior of a single seta. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Methods and CFD Techniques for Drug Application in Brain Tumor Treatment
Authors: Shcherbinina Elena , Turek Stefan
Published: February 2009

In our work, the governing system of equations consists of a mass conservation equation, a momentum equation and an equation for the drug concentration in the brain tumor. This system describes the penetration of drugs into the brain tumor (there is a cavity after surgical removal of a cancer tumor), which fill up the cavity after a surgery. We use techniques of computational fluid dynamics (CFD) to get a solution of the derived partial differential equations (Navier–Stokes equation with additional scalar equations and force terms) and obtain a saddle point problem after discretization of the governing system of equations with finite elements such that we can use modern CFD tools and software like FEATFLOW to get numerical solutions of this problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanical modelling and experimental validation of meniscus replacement material
Authors: Stoffel Marcus , Weichert Dieter , Müller‐Rath Ralf
Published: February 2009

In the present study a condensed collagen gel is investigated for its application as a cartilage replacement material. For this reason, the strength and damping properties are examined experimentally and a theoretical model for predicting specimen deformations and stresses is proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Porous Media Model to Describe the Behaviour of Brain Tissue
Authors: Wagner Arndt , Ehlers Wolfgang
Published: February 2009

The human brain is a very sensitive organ. Even small changes in the cranium cavity can cause life–threatening effects. In case of medical intervention, biomechanics can assist the therapy decisions by simulating the physical behaviour of brain tissue, e.g., the coupled interaction of the fluid motion and the deformation of the brain tissue. In the context of the Theory of Porous Media (TPM), a convenient model of the brain is introduced, which is able to simulate essential mechanical effects in the porous structure of the brain material. The fluid–saturated brain can be treated as an immiscible binary mixture of constituents. In this macroscopic biphasic model, the mixture consists of a solid phase (brain tissue) and a fluid phase (interstitial fluid or blood plasma). Both constituents are assumed to be materially incompressible. The resulting set of coupled partial differential equations is then spatially discretised using mixed finite elements with a backward Euler time integration. Numerical examples are presented illustrating the fundamental effects on the brain tissue under heart–rate dependent pulsative pressure variations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A definition of eddy current penetration depth useful for flaw detection and conductivity measurement
Authors: Dziczkowski Leszek
Published: February 2009

The proposed definition of the penetration depth of eddy currents, more convenient for tests with defectometers, is based on the model: measuring coil placed above non–magnetic conductive foil. The designated penetration depth is equivalent to the penetration depth of a measuring device and is subject of practical observations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of silicon reinforcement on load‐capacity of porous nanofilters
Authors: Kovács Ádám , Kovács András
Published: February 2009

Square–form microfilters consisting of a two–layer porous membrane with nano–size pores and reinforced by silicon columns have been investigated. The change of layer thicknesses and reinforcement geometry modify the load–capacity of the device through the variation of strength properties. A simple thin plate model was constructed by substituting the effect of silicon columns by an equivalent third layer. Estimates for the load–capacity were made by finite element calculations. These estimates have been verified by experimental results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fracture and Damage Analysis of Crimped Glass Fibre Truss Type Elements
Authors: Kreikemeier Janko , Gabbert Ulrich
Published: February 2009

The paper deals with the damage behaviour of special glass fibre reinforced plastic truss type elements, called Polystal profiles, which are widely used as load bearing cables. To connect these profiles with other structural elements steelmade hulls are crimped onto the profiles. The challenge is to detect the optimal crimping ratio (CR) to realize maximum longitudinal loads in restraint systems. By using scanning electron microscopy (SEM) several damage states like fibre pullout and matrix cracking could be observed. To describe the failure behaviour within the rod during crimping a 3D strain based fracture criterion was developed and implemented within the commercial finte element package Abaqus. The verification of this criterion is done by simulating the crimping process followed by tensile tests. The numerical results are compared with the experiments and with the results obtained by SEM. An outlook on further work to improve the failure prediction is given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastodynamic Problem of an Interface Linear Crack under Harmonic Loading
Authors: Mykhailova Iryna I. , Menshykov Oleksandr V. , Guz Igor A.
Published: February 2009

The present work is devoted to application of boundary integral equations to the 2D problem for a linear crack located on the bimaterial interface under harmonic loading. The system of linear algebraic equations is derived to solve the problem numerically. The distribution of the displacements and tractions at the bonding interface and the surface of the crack are obtained for the case of the tension–compression wave which propagates normally to the interface. The results are compared with those obtained for the static case. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deformation and Damage Analysis of a Hybrid‐Forming Tool under Thermal Shock Conditions
Authors: Mahnken R. , Sauerland K.‐H. , Schneidt A. , Gockel F.‐B.
Published: February 2009

In the hybrid–forming process for gradient structures [1] inhomogeneous cyclic thermo–mechanical stresses and strains lead to higher risks of failure of the forming tool. The main topic of this paper is the validation of finite element calculations for a tool–like specimen under complex thermo–mechanical loadings in order to predict the material behaviour [3]. To this end thermal shock experiments of tool–like specimens are performed. Optical measuring systems are used for three–dimensional digitalisation of the specimens to get a sufficient amount of data. Results of experimental optical measurings and results of finite element calculations are compared. Additionally, damage analysis using the eddy current method is performed to characterize the surface state of the cyclically thermal shocked specimens. This damage analysis provides data for lifetime prediction models under thermal shock conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FE‐implementation of plane strain gradient elasticity constitutive equations obtained by homogenization
Authors: Zybell Lutz , Mühlich Uwe , Kuna Meinhard
Published: February 2009

This paper presents a plane strain gradient elasticity model together with a strength criterion based on the maximum hoop stress. It is developed by higher order homogenization based on a cylindrical RVE containing a void and is implemented as mixed–type finite element formulation into the FE–code Abaqus. Numerical simulations are performed in order to study the size effect related to the onset of failure of specimens of porous elastic material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards the analysis of materials with strain gradient effects using ‐Natural Element Method
Authors: Rajagopal A. , Steinmann P.
Published: February 2009

The notion of generalized continua unifies several classes of continuum theories that account for size dependence arising due to the underlying microstructure of the material. In gradient continua, besides the first gradient also the higher gradients of displacements are taken in to account. This results in higher order boundary conditions and C1 continuity requirements. α‐Natural Element Method has been used to this effect for numerical modeling of gradient elasticity. The α‐–Natural Element Method allows the construction of models entirely in terms of nodes and also ensures the linear precision of the interpolant over convex and non convex boundaries. C1 natural neighbor interpolants are achieved by a simple transformation of the Farins interpolant, which are basically obtained by embedding Sibsons natural neighbor coordinates in Bernstein–Bezier surface representation of a cubic simplex. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transient heating of a rotating elastic‐plastic solid shaft
Authors: Arslan E. , Mack W. , Eraslan A. N.
Published: February 2009

Based on Tresca's yield criterion and the flow rule associated with it, the transient plasticization in a rotating elastic–plastic solid shaft with temperature dependent yield stress subject to a temperature cycle is studied. Special attention is paid to the residual stresses. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mehrskalenberechnungen nichtlinear elastischer inhomogener Körper
Authors: Bitzenbauer Johann , Schweizerhof Karl
Published: February 2009

Mehrgittermethoden als besonders schnelle und effiziente Lösungsverfahren für elliptische partielle Differentialgleichungen basieren auf der Diskretisierung des Problems mittels unterschiedlich grober bzw. feiner Netze. Ihre Effizienz leidet jedoch sehr, sobald eine sehr grobe Diskretisierung aufgrund vorhandener komplexer Ränder oder materieller Inhomogenitäten nicht mehr möglich ist. Andererseits führt aber jede klassische FE–Analyse, die komplizierte geometrische Details befriedigend auflöst, zu so vielen Unbekannten, dass nicht multilevelbasierte Gleichungslöser von vorneherein ausscheiden. In [1] werden deshalb Finite–Elemente–Räume entwickelt, deren minimale Dimension nicht mehr mit der Komplexität der Geometrie gekoppelt ist. Diese sogenannte zusammengesetzte Finiten–Elemente–Diskretisierung (CFE) wird über eine Gitterhierarchie definiert. In [2] wird das Konzept auf materiell inhomogene Probleme erweitert. Im Vergleich zu rein algebraisch erzeugten niederdimensionalen Problemen werden bei diesem Vorgehen zusätzliche Geometrieinformationen genutzt. Für einfache eindimensionale Problemklassen besteht kein prinzipieller Unterschied zwischen CFE– und algebraisch motivierten Methoden; dies ändert sich jedoch bei den hier betrachteten zweidimensionalen Problemen der nichtlinearen Elastizitätstheorie. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐linear dynamic contact of thin‐walled structures
Authors: Cichosz Thomas , Bischoff Manfred , Hartmann Stefan , Ramm Ekkehard
Published: February 2009

In many areas of mechanical engineering contact problems of thin–walled structures play a crucial role. Car crash tests and incremental sheet metal forming can be named as examples. But also in civil engineering, for instance when determining the moment–rotation characteristics of a bolted beam–column joint, contact occurs. Effective simulation of these and other contact problems, especially in three–dimensional non–linear implicit structural mechanic is still a challenging task. Modelling of those problems needs a robust method, which takes the thin–walled character and dynamic effects into account. We use a segment–to–segment approach for discretization of the contact and introduce Lagrange Multipliers, which physically represent the contact pressure. The geometric impenetrability condition is formulated in a weak, integral sense. Choosing dual shape functions for the interpolation of the Lagrange Multipliers, we obtain decoupled nodal constraint conditions. Combining this with an active set strategy, an elimination of the Lagrange multipliers is easily possible, so that the size of the resulting system of equations remains constant. Discretization in time is done with the implicit Generalized‐α Method and the Generalized Energy–Momentum Method. Using the “Velocity–Update” Method, the total energy is conserved for frictionless contact. Various examples show the performance of the presented strategies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Seismic response of secondary structures mounted on ductile frames
Authors: Furtmüller Thomas
Published: February 2009

This paper deals with the response of vibration prone non–structural components (or secondary structures) mounted on regular generic plane frames (i.e. primary structures) subjected to ground–accelerations generated by ordinary earthquakes. The response of these multi–degree–of–freedom (MDOF) systems is approximated utilizing constant–ductility floor response spectra of two–degree–of–freedom (2DOF) primary–secondary systems and validated by the response derived by a fully coupled analysis of the entire primary–secondary system. Furthermore, results of coupled and decoupled analyses are set in contrast. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of thin laminated plates by means of the scaled boundary finite element method
Authors: Hebel Jochen , Becker Wilfried
Published: February 2009

A new scaled boundary finite element formulation for the static analysis of laminated plates is presented. The problem is formulated in scaled boundary coordinates using a discrete form of the reduction method by Kantorovich. The resulting systems of linear ordinary differential equations for the unknown displacement functions are solved analytically. Element stiffness matrices can be calculated from the appropriate solution subsets for bounded and unbounded domains. From the inherent field expansion in one spatial direction, exponents and coefficients can be extracted efficiently. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Features of an adaptive remeshing strategy in the context of deformation localization and high speed cutting
Authors: Hortig Christian , Gu Xin , Svendsen Bob
Published: February 2009

The purpose of this work is the modeling and simulation of shear banding and chip formation during high–speed cutting. Here, the use of error estimation and adaptive remeshing is of special interest. The current work investigates the application of different refinement strategies on the problem of adiabatic shear banding. As a result the authors will present a combination of a recovery based error estimation and a refinement indicator. Simulation results for the high speed cutting process will be presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the Lateral Eigenstrains on the Transverse Displacement of Wide Beams
Authors: Huber D. , Krommer M. , Irschik H.
Published: February 2009

The present paper studies the influence of lateral eigenstrains on the transverse deflection of wide beams. We show that in this case a laterally nonuniform transverse displacement becomes notable; moreover, it turns out that the axial variation of the transverse displacement is significantly altered in comparison to the results obtained from beam theory. In order to derive a corrected analytical solution for the transverse displacement of wide beams, the latter are modeled as thin plates with induced eigenstrains in both in–plane directions. A Galerkin method is utilized to solve the plate equations, in which solutions for the transverse displacement resulting from beam theory are used as shape functions for the plate deflection. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An elastodynamic Galerkin Boundary Element Formulation for semi‐infinite domains in time‐domain
Authors: Kielhorn Lars , Schanz Martin
Published: February 2009

The present work focuses on the problem of modelling wave propagation phenomena within a 3–d elastodynamic halfspace by use of a symmetric Galerkin Boundary Element formulation. Unfortunately, this formulation requires the evaluation of hypersingular integral kernels which are regularized by integration by parts.

In Boundary Element Methods semi–infinite domains are commonly approximated in space by considering just a sufficiently large enough region. Applying this simple discretization to the symmetric formulation implies the evaluation of the hypersingular bilinear form on a truncated mesh which will fail due to the regularization approach. To overcome this drawback a methodology based on infinite elements is presented. The numerical tests show that this approach is promising for treating semi–infinite domains with a symmetric Galerkin scheme. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of dynamic loads acting on carrying cable in operating ropeway
Authors: Knawa Marta , Bryja Danuta
Published: February 2009

The model of a carrying rope under in–service loads is developed to analyze dynamic response of the cable during ropeway operation including: start conditions while carriers leave the station, steady ride, an emergency stop of a system. The pendulum model of a moving passenger carrier is formulated to define loads acting on the cable. Equations of motion of the cable loaded by moving pendulums are derived by applying Ritz approximate method and Lagrangian description of motion. Some numerical results are presented to illustrate applicability of proposed method in an investigation of carrying cable vibrations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometrical covariant approach for contact between curves representing beam and cable type structures
Authors: Konyukhov Alexander , Schweizerhof Karl
Published: February 2009

The geometrical approach for curve–to–curve interaction is considered in a specially defined local coordinate system related to the contacting curve. This coordinate system is defined following the closest point projection (CPP) procedure in which two nearest contact points are defined correspondingly on both curves. The iterative numerical algorithm is then formulated in this coordinate system and all necessary parameters are derived in a covariant form. This leads to a contact description which is applicable for contact between curved beams and cables as well as for contact between surface edges. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational analysis in dynamical problems of linear elasticity
Authors: Kostin Georgy , Saurin Vasily
Published: February 2009

The initial–boundary value problems in the linear theory of elasticity is considered. Based on the method of integrodifferential relations (MIDR) two dynamical variational principles is proposed and discussed. It is shown that the Hamilton principle as well as the corresponding complementary principle stated for dynamic boundary value problems follow out the variational formulations proposed. To minimize the nonnegative functional under algebraic and differential constraints a regular finite element algorithm is worked out. The algorithm allows us to estimate explicitly the local and integral quality of numerical solutions obtained. A 3D problem of lateral motions of a rectilinear elastic prism with a rectangular cross section are considered. The numerical results are presented and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive Cross Approximation in an elastodynamic Boundary Element formulation
Authors: Messner Matthias , Schanz Martin
Published: February 2009

Elastodynamic phenomena can be effectively analyzed by using the Boundary Element Method (BEM), especially in unbounded media. However, for the simulation of such problems, beside others, two difficulties restrict the BEM to rather small or medium–sized problems. Firstly, one has to deal with dense matrices and secondly the treatment of the kernel functions is very costly. Several approaches have been developed to overcome these drawbacks. Approaches, such as Fast Multipole and Panel Clustering etc. gain their efficiency basically from an analytic kernel approximation. The main difficulty of these methods is that the so called degenerate kernel has to be known explicitly.

Hence, the present work focuses on a purely algebraic approach, the adaptive cross approximation (ACA). By means of a geometrical clustering and a reliable admissibility condition, first, a so called hierarchical matrix structure is set up. Then each admissible block can be represented by a low–rank approximation. The advantage of the ACA is based on the fact that only a few of the original matrix entries have to be generated.

As will be shown numerically, the presented approach is suitable for an efficient simulation of elastodynamic problems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Explicit Buckling Analysis and Design Equations for Composite Plates under Compression with Free Reinforced Edges
Authors: Mittelstedt Christian , Schager Martin
Published: February 2009

In the present contribution, the buckling problem of compressively loaded symmetrically laminated orthotropic composite plates with free reinforced edges is studied [1]. Starting from the exact transcendental elasticity solution of the problem, a straightforward criterion for the determination of the minimum bending stiffness EImin of the edge stiffeners is presented that allows for the determination of EI such that no global buckling of the plate and flange occurs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Excitation of Rolling Tires from the Road Surface Texture
Authors: Brinkmeier M. , Nackenhorst U. , Suwannachit A.
Published: February 2009

Rolling tires are excited from the contact with the rough road surface to vibrations, which cause rolling noise. A two scale approach is suggested, where at the macro–scale the vibration of the rolling tire structure is modeled by quite detailed finite element methods. The road surface is described using measured textures. A fine resolution finite element discretization of the tread rubber is performed in order to resolve the asperity contact. The material properties are described by a non–linear viscoelastic rubber model. The tread patch is enforced to approach the rough surface in a transient dynamics manner. From these investigations an enveloping surface profile is reconstructed to be used for the excitation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An exact sinusoidal beam finite element
Authors: Pawlak Zdzislaw , Rakowski Jerzy
Published: February 2009

The purpose of the paper is to derive an efficient sinusoidal thick beam finite element for the static analysis of 2D structures. A two–node, 6–DOF curved, sine–shape element of a constant cross–section is considered. Effects of flexural, axial and shear deformations are taken into account. Contrary to commonly used curvilinear co–ordinates, a rectangular co–ordinates system is used in the present analysis. First, an auxiliary problem is solved: a symmetric clamped–clamped sinusoidal arch subjected to unit nodal displacements of both supports is considered using the flexibility method. The exact stiffness matrix for the shear–flexible and compressible element is derived. Introduction of two parameters “n” and “t” enables the identification of shear and membrane influences in the element stiffness matrix. Basing on the principle of virtual work a full set of 18 shape functions related to unit support displacements is derived (total rotations of cross–sections, tangential and normal displacements along the element). The functions are found analytically in the closed form. They are functions of one linear dimensionless coordinate of x–axis and depend on one geometrical parameter of sinusoidal arch, height/span ratio “c” and on physical and geometrical properties of the element cross–section. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plateau regularization method for structural shape optimization and geometric mesh control
Authors: Wüchner R. , Firl M. , Linhard J. , Bletzinger K.‐U.
Published: February 2009

Within this contribution the algorithmic treatment of the inverse problem of finding mechanically motivated membrane shapes is discussed and the key point, that the corresponding numerical methods have a broader spectrum of applications which enables their adoption to similar problems from other disciplines, is highlighted. The presented adaptive scheme is the Updated Reference Strategy (URS) enhanced by a newly derived “element distortion control”. The key feature is the ability of the proposed stabilized scheme to overcome the singular problem of finding equilibrium shapes of prestressed membranes which is due to the non–uniqueness of nodal positions in the finite element mesh and the purposeful adjustment of the underlying stress state based on a local geometrical criterion in case of incompatible stress states. Therefore, the derived methodology is –beside the mere computation of equilibrium configurations– able to distribute (probably very local) deformations of the mesh in a smooth way to the whole domain by at the same time conserving specific mesh characteristics which guarantees regular meshes with high quality concerning the element shape. This results in robust computations even for complex and problematic geometrical situations. Due to the effective mesh control of this approach a transfer of the developed methodology to other fields of application like e.g. mesh smoothing, large displacement mesh moving problems and stabilized CAD–free shape optimization of shells is promising and therefore accomplished. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural vibration control by means of nonlinear pendulum dampers
Authors: Yousefi Seyed Mehdi , Heuer Rudolf
Published: February 2009

This paper discusses the application of a nonlinear Pendulum Tuned Mass Damper (PTMD) for the reduction of structural vibrations. Pendulum dynamic absorbers are used extensively to reduce the vibration level of slender elastic structures such as towers. A PTMD is a device consisting of a suspended mass, and a damper that is attached to the tower in order to reduce its dynamic response. The primary eigenfrequency of the nonlinear damper is tuned to a particular structural frequency. Energy is dissipated by the damping force acting on the structure. Here, the PTMD is applied to a tower as a continuous system consisting of distributed mass and elasticity. The optimum values of PTMD parameters are found based on minimization of the response of the tower tip–point. Time history and frequency domain responses for the tower with PTMD in linear and nonlinear condition are compared. In addition, the equations of motion of active pendulum control are intruduced. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wechselwirkung bewegter Temperaturfelder mit Zellulären Automaten
Authors: Bode K.H. , Ostermeyer G.‐P.
Published: February 2009

Die Reibung in Bremsen und Kupplungen unterliegt einer Dynamik, die durch eine Vielzahl komplexer Vorgänge, insbesondere durch eine Wechselwirkung der Größen “Reibwert” und “Verschleiß”, bedingt ist [1]. Diese Erkenntnis motiviert die Entwicklung diskreter Modelle, mit denen die lastabhängige Ausbildung der Grenzschicht erfassbar ist [2].

Eine Einbeziehung tribochemischer Reaktionen, denen bei einer material– bzw. mischungssensitiven Simulation der Reibung eine erhebliche Bedeutung zukommt, erfordert eine genaue Kenntnis der Temperaturen in der Grenzschicht. Vor diesem Hintergrund wird ein bestehender Algorithmus nach der Methode der Zellulären Automaten [3] verwendet und hier vertiefend betrachtet.

Im Einzelnen widmet sich dieses Paper der Anwendung auf das dreidimensionale Problem einer über die Oberfläche eines raumfesten Körpers bewegten Wärmequelle. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐trimester maternal serum matrix metalloproteinase‐9 (MMP‐9) and adverse pregnancy outcome
Authors: Poon Leona C. Y. , Nekrasova Ekaterina , Anastassopoulos Panagiotis , Livanos Panagiotis , Nicolaides Kypros H.
Published: February 2009

Objective

To investigate the potential value of maternal serum matrix metalloproteinase‐9 (MMP‐9) in first‐trimester screening for preeclampsia and spontaneous early preterm delivery.

Methods

The concentrations of MMP‐9, tumour necrosis factor soluble receptor‐1 (TNF‐R1), pregnancy‐associated plasma protein‐A (PAPP‐A) and uterine artery pulsatility index (UA‐PI) were measured at 11+0 − 13+6 weeks in cases of preeclampsia (n = 128), gestational hypertension (n = 88), small for gestational age (n = 296), spontaneous early preterm delivery (n = 57) and controls (n = 569). The distributions of measured metabolites and UA‐PI in the control and adverse outcome groups were compared. Logistic regression analysis was used to determine the significant contributors in the prediction of adverse outcomes.

Results

The median MMP‐9 was higher than controls in the preeclampsia (1.190 MoM) and preterm delivery (1.187 MoM) groups. In the preeclampsia group there was a significant association between serum MMP‐9 and TNF‐R1 (r = 0.523, P < 0.0001). Significant prediction of preeclampsia was provided by history and UA‐PI, and prediction of preterm delivery was provided by history and neither was improved by the addition of MMP‐9.

Conclusion

In pregnancies developing preeclampsia, the increased level of MMP‐9 and the good correlation with TNF‐R1 suggest the presence of an underlying inflammatory process. In the pregnancies resulting in spontaneous preterm delivery the small increase in MMP‐9 is not useful in the prediction of preterm delivery. Copyright © 2009 John Wiley & Sons, Ltd.
Performance of five different electrospray ionisation sources in conjunction with rapid monolithic column liquid chromatography and fast MS/MS scanning
Authors: Burgess Karl E. V. , Lainson Alex , Imrie Lisa , Fraser‐Pitt Douglas , Yaga Raja , Smith David G. E. , Swart Remco , Pitt Andrew R. , Inglis Neil F.
Published: February 2009

The performances of five different ESI sources coupled to a polystyrene–divinylbenzene monolithic column were compared in a series of LC‐ESI‐MS/MS analyses of Escherichia coli outer membrane proteins. The sources selected for comparison included two different modifications of the standard electrospray source, a commercial low‐flow sprayer, a stainless steel nanospray needle and a coated glass Picotip. Respective performances were judged on sensitivity and the number and reproducibility of significant protein identifications obtained through the analysis of multiple identical samples. Data quality varied between that of a ground silica capillary, with 160 total protein identifications, the lowest number of high quality peptide hits obtained (3012), and generally peaks of lower intensity; and a stainless steel nanospray needle, which resulted in increased precursor ion abundance, the highest‐quality peptide fragmentation spectra (5414) and greatest number of total protein identifications (259) exhibiting the highest MASCOT scores (average increase in score of 27.5% per identified protein). The data presented show that, despite increased variability in comparative ion intensity, the stainless steel nanospray needle provides the highest overall sensitivity. However, the resulting data were less reproducible in terms of proteins identified in complex mixtures – arguably due to an increased number of high intensity precursor ion candidates.
Comparison of two combinations of cyanine dyes for prelabelling and gel electrophoresis
Authors: Tsolakos Nikos , Techanukul Tanasit , Wallington Amanda , Zhao Yuan , Jones Christopher , Nagy Judit , Wheeler Jun X.
Published: February 2009

We report the use of IC‐OSu ethyl‐Cy3 and ethyl‐Cy5 N‐hydroxysuccinimide ester (NHS) cyanine dyes, which have similar chemical properties as the CyDye™ DIGE fluor minimal dyes for pre‐electrophoresis labelling. Multiple sample analyses in different laboratories indicate that the use of IC‐OSu ethyl‐Cy3 and ethyl‐Cy5 NHS ester cyanine dyes produces equivalent results to those obtained with DIGE CyDyes, and allows sample multiplexing and accurate quantitation for differential proteome analysis.
Description of vibrational properties of random alloy ZnTe1–xSex within the percolation model
Authors: Souhabi Jihane , Chafi Allal , Kassem Mohammed , Nassour Ayoub , Gleize Jérôme , Postnikov A. V. , Hugel J. , Pagès Olivier
Published: February 2009

We discuss the classification of the phonon type behavior of semiconductor alloys as apparent in the Raman and infrared spectra, i.e. in terms of types (i) 1‐bond→1‐mode and (ii) 2‐bond→1‐mode (both covered by the Modified Random Element Isodisplacement model, operating at the macroscopic scale), and also (iii) the modified 2‐mode type (exceptional), in the framework of the recent 1‐bond→2‐mode percolation model based on a description of the alloy disorder at the mesoscopic scale. The leading systems of types (i) and (iii), i.e., InGaAs and InGaP, respectively, were earlier shown to obey the percolation model. The aim of this work is to investigate whether the percolation model further extends to the leading system of the last type (ii), i.e. ZnTeSe. With this end in view, we perform a careful re‐examination of the Raman and infrared spectra of this alloy, as available in the literature. Special attention is awarded to the discussion and modeling of the puzzling multi‐mode infrared reflectivity spectra. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dielectric functions of CuIn1+2nSe2+3n and CuGa1+2nSe2+3n (n = 2.5, 3.0, 3.5)
Authors: León Máximo , Serna Rosalía , Gurieva Galina , Levcenko Sergei , Friedrich Eberhardt Josué , Merino José Manuel , Arushanov Ernest
Published: February 2009

The dielectric functions ϵ(ω) = ϵ1(ω) +i ϵ2(ω) of CuIn1+2nSe2+3n and CuGa1+2nSe2+3n (n = 2.5, 3.0, 3.5) have been determined in the photon energy range from 0.8 to 4.7 eV by spectroscopic ellipsometry. The measurements reveal distinct structures at energies of the critical points in the Brillouin zone. The structure observed in the spectral dependence of the dielectric functions, the complex refractive index, the absorption coefficient and the normal‐incidence reflectivity has been modelled using a modification of the Adachi's model. The results are in a good agreement with the experimental data over the entire range of photon energies. The model parameters (strength, threshold energy and broadening) have been determined using the simulated annealing algorithm. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of Cu(In,Al)Se2 thin films by selenization using diethylselenide
Authors: Umezawa Akihisa , Yasuniwa Toshihiro , Miyama Atsushi , Nakanishi Hisayuki , Sugiyama Mutsumi , Chichibu Shigefusa F.
Published: February 2009

Selenization growth of purely single‐phase, polycrystalline CuIn1–x Alx Se2 (0 ≤ x ≤ 0.26) alloy films was demonstrated using a less‐hazardous metal‐organic selenide, diethylselenide [(C2H5)2Se: DESe]. Without additional thermal annealing, approximately 2.0‐μm‐thick alloy films exhibiting X‐ray diffraction peaks originating exclusively from the chalcopyrite structure were obtained. Their low temperature photoluminescence spectra were dominated by characteristic donor‐acceptor pair emissions usually seen in the state‐of‐the‐art CuInAlSe2 photoabsorbing layers. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ga‐doped ZnO transparent conducting films prepared by helicon‐wave‐excited plasma sputtering
Authors: Masaki Shingo , Nakanishi Hisayuki , Sugiyama Mutsumi , Chichibu Shigefusa F.
Published: February 2009

Gallium‐doped zinc oxide (ZnO:Ga) transparent conducting films were prepared by the helicon‐wave‐excited plasma sputtering (HWPS) method. The films exhibited a dominant [0001]‐oriented growth with a small full width at half maximum of the (0002) ZnO diffraction peak (0.28 degrees). A high optical transmittance greater than 80% was achieved in the wavelength range between 400 and 1600 nm, because the HWPS method essentially does not damage the film surface. The results indicate that CdS‐free Cu(In,Ga)Se2‐based solar cells may be fabricated by sputtering ZnO:Ga directly on the Cu(In,Ga)Se2 layer using the HWPS method. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of Zn‐doped Cu(In,Ga)Se2 thin film solar cells prepared by Zn diffusion from the gas phase using dimethylzinc
Authors: Miyama Atsushi , Dou Xiaoming , Yasuniwa Toshihiro , Umezawa Akihisa , Nakanishi Hisayuki , Chichibu Shigefusa F. , Sugiyama Mutsumi
Published: February 2009

Cu(In,Ga)Se2 (CIGS) solar cells were fabricated by thermal diffusion of Zn into p ‐type CIGS films using dimethylzinc [(CH3)2Zn: DMZn] vapor, in order to form CIGS pn ‐homojunction. This method requires no additional processing equipment, because diffusion can be carried out subsequent to the CIGS growth. The average conversion efficiency of the CIGS solar cells consisting of n ‐type MgZnO transparent conducting oxide (TCO) film and n ‐CIGS:Zn/p ‐CIGS structure (4%) was improved by a factor of two in comparison with the case for undoped CIGS absorbing layer (2%). The appropriate flow time of DMZn was 3 s, from which the diffusion depth is estimated as about 150 nm. The method is highly advantageous for development of low‐cost solar modules. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase relations in the CuInSe2–CuBiSe2 semiconductor system
Authors: Korzun B. V. , Fadzeyeva A. A. , Maroz I. I.
Published: February 2009

Alloys of the (CuBiSe2)1–x(CuInSe2)x system with molar part of CuInSe2 (x) equal to 0.05, 0.15, 0.25, 0.375, 0.50, 0.625, 0.75, 0.85, and 0.95 were prepared and the phase relations in this system above 600 K were investigated by using of X‐ray powder diffraction, microstructure studies, and differential thermal analysis. It was established, that the T–x phase diagram of the CuInSe2–CuBiSe2 system has a peritectic character with the peritectics temperature of 837 K. The limits of solubility from both sides of the system do not exceed 0.05 molar parts of the corresponding ternary compound. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two fast radiative transfer methods to improve the temporal sampling of clouds in numerical weather prediction and climate models
Authors: Manners J. , Thelen J.‐C. , Petch J. , Hill P. , Edwards J.M.
Published: February 2009

The high computational cost of calculating the radiative heating rates in numerical weather prediction (NWP) and climate models requires that calculations are made infrequently, leading to poor sampling of the fast‐changing cloud field and a poor representation of the feedback that would occur. This paper presents two related schemes for improving the temporal sampling of the cloud field. Firstly, the ‘split time‐stepping’ scheme takes advantage of the independent nature of the monochromatic calculations of the ‘correlated‐k’ method to split the calculation into gaseous absorption terms that are highly dependent on changes in cloud (the optically thin terms) and those that are not (optically thick). The small number of optically thin terms can then be calculated more often to capture changes in the grey absorption and scattering associated with cloud droplets and ice crystals. Secondly, the ‘incremental time‐stepping’ scheme uses a simple radiative transfer calculation using only one or two monochromatic calculations representing the optically thin part of the atmospheric spectrum. These are found to be sufficient to represent the heating rate increments caused by changes in the cloud field, which can then be added to the last full calculation of the radiation code. We test these schemes in an operational forecast model configuration and find a significant improvement is achieved, for a small computational cost, over the current scheme employed at the Met Office. The ‘incremental time‐stepping’ scheme is recommended for operational use, along with a new scheme to correct the surface fluxes for the change in solar zenith angle between radiation calculations. Copyright © Crown Copyright 2009. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd.