bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fourier‐Analyse versus Wavelet‐Analyse
Authors: Schlagner S. , Strehlau U. 
Published: December 2005

AbstractSollen aus Zeitsignalen y (t ) spezifische Informationen gewonnen werden, so kann dies mit Hilfe geeigneter Analysen, also Transformationen geschehen. Die wohl bekannteste Transformation ist die Fourier‐Transformation, welche ein Signal spektral, d.h. in seinen Frequenzinhalten darstellt. Da diese Transformation das zu transformierende Signal als Gesamtobjekt betrachtet, beinhaltet sie nur globale Frequenzinformationen. Oft ist jedoch eine zeitliche Einordnung spektraler Eigenschaften instationärer Signale, z. B. bei der Lokalisierung von Stößen von Interesse. Dies kann die Fourier‐Transformation nicht leisten. An dieser Stelle bietet die Short‐Time‐Fourier‐Transformation bedingt eine Möglichkeit der zeitlichen Zuordnung spektraler Eigenschaften, indem sie das Signal in Zeitbereiche unterteilt.Eine bessere Möglichkeit zur Untersuchung instationärer Signale stellt die Wavelet‐Transformation dar. Sie kann Signalstrukturen zeitlich besser erfassen und bietet somit dieMöglichkeit, sowohl den Frequenzinhalt als auch die Frequenzdynamik zu untersuchen. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrations of Pipes with Internal Flow and Rigid Body Degrees of Freedom
Authors: Stangl Michael , Irschik Hans 
Published: December 2005

AbstractIn the present paper the nonlinear dynamics of elastic pipes conveying fluid at arbitrary flow rates are investigated. The nonlinear equations of motion are derived using a unified form of the Lagrange Equations for non‐material volumes formulated by Irschik and Holl [1], see also Chapter 3 of [2]. In a first step cantilevered pipes are considered using elastic degrees of freedom combined with a Ritz‐Galerkin Ansatz of arbitrary order for modelling the deformations of the pipes. The Lagrange Equations for non‐material volumes include a nonzero surface integral of the kinetic energy due to the moving outlet surface at the end of the pipe. The linear equations of motion obtained from this model are then analytically investigated utilizing the corresponding Eigenvalue problem. The results are visualized in an Argand representation of the corresponding Eigenvalues of the system matrix and compared to existing results obtained by using different formulations, such as the Hamilton Principle for Open‐Systems, formulated by Benjamin [4], as demonstrated by Païdoussis [5], see also chapter 3.5 of [6]. In a next step an elastic pipe with a rigid body degree of freedom combined with a Ritz‐Galerkin Ansatz is modelled with one supported and one free end. The derivation of the equations of motion is performed by using a floating‐frame of reference formulation which leads to a system of nonlinear second order differential equations describing the motion of the pipe. Finally, the stability of the solutions of the equations of motion for varying flow rate is studied numerically. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability and stabilisation of acausal discrete linear repetitive processes
Authors: Galkowski Krzysztof , Kummert Anton , Cichy Blazej , Rogers Eric 
Published: December 2005

AbstractRepetitive processes are a distinct class of two‐dimensional systems (i.e. information propagation in two independent directions occurs) of both systems theoretic and applications interest. In this paper we introduce a new model for these processes in order to represent dynamics which arise in some applications areas and which are not included in those currently available. Then we proceed to de.ne quadratic stability for this case, obtain conditions for its existence, and also use feedback control to solve a stabilization problem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal Control of Iterative Solution Methods for Linear Systems of Equations
Authors: Helmke Uwe , Jordan Jens 
Published: December 2005

AbstractIterative solution methods for linear systems of equations can be regarded as discrete‐time control systems, for which a stabilizing feedback control has to be found. Well known algorithms such as GMRES(m) may exhibit unstable dynamics or sensitive dependence on initial conditions, thus preventing the algorithm to converge to the desired solution. Based on linear system feedback design techniques a new algorithm is proposed that does not suffer under such shortcomings. Global convergence to the desired solution is shown for any initial state. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of Vertebrae Motion with Computer Simulation Using Elementary Contact Pairs
Authors: Liem K. , Dhanu Singh M. , Kecskeméthy A. 
Published: December 2005

AbstractTo simulate the motion of two adjacent vertebrae a computer model is created. Described in the paper is the mathematical modelling of a vertebrae pair using multibody methods and impact analysis techniques with elementary contact geometry for the facet joints. The ligaments and the intervertebral disc are modeled as a parallel connection of a spring and a damper. The results are compared with existing approaches and experimental data. In order to enhance the results, piecewise linear functions instead of a constant spring stiffness for the model of the intervertebral disc are used. The simulation allows the motion in three‐dimensional space (three translations and three rotations, see figure 1). The investigations are focused on the vertebrae pair C5‐C6 but can be easily extended to other vertebrae. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On artificial geometry errors in the adaptive analysis of eigenvalues and eigenmodes of curved shell structures using the finite element method
Authors: Ewert Eduard , Schweizerhof Karl 
Published: December 2005

AbstractThe standard procedure to compute design loads for shell structures as also proposed in design rules is based on the computation of the limit load taking into account the modification of the so‐called stability loads due to geometrical imperfections. The imperfections are mostly chosen affine to the buckling patterns, which are solutions of the eigenvalue‐problem for the geometrically perfect structure. Thus, the eigenvalue‐problems for stability points have to be solved very accurately. In the present contribution an adaptive h ‐refinement procedure is taken for the solution using low order shell elements. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A general polyconvex strain‐energy function for fiber‐reinforced materials
Authors: Markert Bernd , Ehlers Wolfgang , Karajan Nils 
Published: December 2005

AbstractThe continuum mechanical modeling and numerical simulation of fiber‐reinforced materials, such as carbon‐fiber‐reinforced plastics or collagenous biological tissues, are of great interest in the field of material science. In this regard, various strainenergy functions have been proposed to capture the inherent anisotropy of these types of materials ranging from simple exponential functions applied in biomechanics [5] to more sophisticated formulations based on the theory of invariants [8]. The goal of this contribution is to present an alternative ansatz, which basically adopts the general idea of the wellestablished isotropic hyperelasticity law of Ogden [7]. In particular, a polynomial strain‐energy function formulated in the fiber stretch is proposed, which allows the description of the general nonlinear elastic response of various kinds of fiber materials, such as collagen, nylon or sisal, in a very concise form. Moreover, the formulation still meets the requirements of a stress‐free reference state and material stability, whereas the number of material parameters is kept to a minimum. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Imperfection Sensitivity and Limit Loads of Spherical Shells under Radial Pressure
Authors: Pontow Jens , Dinkler Dieter 
Published: December 2005

AbstractThe evaluation of the imperfection sensitivity of shell structures and the estimation of their limit loads are widely discussed phenomena. The perturbation energy concept according to Dinkler et al. [1], [2] enables to assess the imperfection sensitivity of shell structures by means of an energy value, the perturbation energy. A buckling criterion may be developed from the comparison between the perturbation energy and experimental data. This paper focuses on the imperfection sensitivity and limit loads of spherical shells of revolution under radial pressure. The investigations include the influence of the meridional angle and different types of boundary conditions. By comparing the numerical results with the German design rule DIN 18800, critical values for the perturbation energy are derived to predict the limit loads. These critical values for the perturbation energy allow to judge whether the German design rule DIN18800 predicts the limit loads of spherical shells under external pressure with varying meridional angles and different boundary conditions with the same reliability in respect of the perturbation energy. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of linear and nonlinear elastic columns under action of a parametric force in form of a random stationary process
Authors: Treckmann Malte , Potapov Vadim D. 
Published: December 2005

AbstractForces on structures, which are often simplified assumed as static loads, are frequently exhibited as random processes. Statements about the stability of similar structures can be determined i.e. by help of numeric procedures, which are based on methods using the Lyapunov‐exponent. Furthermore, the stability of systems made from nonlinear material is considered. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Abaqus‐Implementierung eines Dehnungsraum‐Stoffgesetzesnach Besdo
Authors: Besdo D. , Ihlemann J. , Kirbach J. 
Published: December 2005

AbstractDas Lagrange‐formulierte Materialgesetz im Dehnungsraum nach Besdo [1] berücksichtigt Effekte der isotropen Verfestigung und Formen der Anisotropie (plastisch induzierte und kinematische Verfestigung) unter Berücksichtigung des plastic spin . Oftmals ist es bereits bei der Formulierung eines Materialgesetzes (elastisches Potential, Fließregel, Fließbedingung) notwendig, sich den Konventionen des anvisierten FE‐Programmsystems anzupassen, weil der Übergang zwischen der Eulerschen und der Lagrangeschen Betrachtungsweise unter Beibehalt identischer tensorieller Aussagen nicht gelingt. Mit Hilfe des Übertragungsoperators nach Ihlemann [2] ist ein freier Umgang in der Betrachtungsweise möglich. Am Beispiel der Materialtangente nach Besdo [4] wird nun das Konzept des Übertragungsoperators auf 4‐stufige Tensoren erweitert und dessen Anwendung zur Aufbereitung einer Abaqus‐konformen Steifigkeitsmatrix demonstriert. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Formulation of Finite Viscoplasticity for Glassy Polymers in the Logarithmic Strain Space
Authors: Göktepe Serdar , Méndez Joel , Miehe Christian 
Published: December 2005

AbstractThis contribution extends the recently proposed kinematical approach by Miehe et al. [4] to a constitutive formulation for elasto–visco–plastic behavior of amorphous glassy polymers below their glass transition temperature. In contrast to the existing kinematical approaches in the literature, the latter is constructed in the logarithmic strain space yielding a formulation analogous to the geometrically linear theory of plasticity in the six–dimensional space. Its analogy to a geometrically linear theory makes this formalism very attractive, especially with regard to its algorithmic implementation. Conceptually, elasto–visco–plastic model with an intrinsic non–linear kinematic hardening is considered in the logarithmic strain space. The evolution law of the plastic strains is adopted from Argon's [1] double–kink theory. The proposed formulation is validated by means of experimental data obtained from both homogeneous and non–homogeneous experiments. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and simulation of chip formation in high speed cutting
Authors: Hortig Christian , Svendsen Bob 
Published: December 2005

AbstractThe purpose of this short work is the thermomechanical modeling of shear band and chip formation during high‐speed cutting. Shear bands develop in areas of maximal mechanical dissipation in which temperature‐dependent softening dominates strainand strain‐rate‐dependent hardening. In the simulations, the well‐known problem of the mesh‐dependence of the shear‐band development is addressed, involving both mesh size and mesh orientation. An example simulation is presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solution‐precipitation creep – micromechanical modelling and numerical results
Authors: Ilić Sandra , Hackl Klaus 
Published: December 2005

AbstractOur aim is to present a continuum mechanical model for solution‐precipitation creep as well as to compare the numerical results based on that model with experimental observations. The formulation of the problem is based on the minimization of a Lagrangian consisting of elastic power and dissipation. Elastic energy is chosen to be in a standard form but dissipation is strongly adapted to the solution‐precipitation process by introducing two new quantities: the velocity of material transport within the crystallite‐interfaces and the normal velocity of precipitation or solution respectively. The model enables one to give an analytical solution for the case of a single crystal and numerical solution based on a finite element method for more complex, polycrystalline materials. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and simulation of induced anisotropy and directional hardening effects due to an evolving microstructure in metals
Authors: Wang J. , Levkovitch V. , Reusch F. , Svendsen B. 
Published: December 2005

AbstractThe purpose of the current work is the formulation, numerical implementation and application of a material model for anisotropic hardening in metals taking the interplay between the the direction of inelastic deformation, the orientation of dislocation structures, and the current deformation/loading direction into account. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element modeling of piezoelectric materials with a superimposed stress
Authors: Arockiarajan A. , Delibas B. , Menzel A. , Seemann W. 
Published: December 2005

AbstractBased on the mechanism of domain switching, a three dimensional nonlinear finite element model for piezoelectric materials subjected to electromechancial loading is developed in this contribution. The finally considered model problem deals with differently oriented grains whereby uni‐axial, quasi‐static cyclic loading is applied. It is assumed that a crystal orientation switches if the reduction in free energy of the grain exceeds a critical energy barrier. The nonlinearity in the small electromechanical loading range is addresses via a polynomial probability function for domain switching. Hysteresis behavior is discussed taking the influence of a superimposed compression state into account. It is observed that the hysteresis loop flattens under the axial compression but elongates under the transverse compression. Irrespective of how the compression is applied, the remnant polarization and as well as the coercive electric field decrease. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Anisotropic Damage in Arterial Walls
Authors: Balzani Daniel , Schröder Jörg , Gross Dietmar 
Published: December 2005

AbstractIn a certain range of overexpansion arterial walls are characterized by an orthotropic elastic material behavior. Due to different stabilities of the helically arranged fibers, i.e. breakage of collagen crosslinks between the fibers, damage effects are observed in experiments. Because of the fibrous composition it is assumed that damage mainly occurs in the fiber direction. The proposed damage model is extended to arterial wall applications by introducing a referential damage state. The damage approach is applied to a polyconvex model for the hyperelastic behavior of arteries in order to obtain a materially stable model, which guarantees the existence of solutions of the underlying boundary value problem. The performance of the proposed model is presented in a numerical example, where the overexpansion of an atherosclerotic artery is simulated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computer simulations for the mechanical analysis of skeletal muscles
Authors: Böl Markus , Reese Stefanie 
Published: December 2005

AbstractThe structure of a skeletal muscle can be seen as a complex hierarchical organisation in which thousands of muscle fibers are arranged within a connective tissue network. Inside of the single muscle fibre many force‐producing cells, known as sarcomeres, are connected and take care of the contraction of the whole muscle. The material behaviour of muscles is nonlinear. Due to the fact that muscles can have large deformations in space, geometrical non‐linearities must additionally be taken into account. For the simulation of such a behaviour the finite element method is used in the present approach. The material behaviour of the muscle is split into a so‐called active and a passive part. To describe the passive part special unit cells consisting of one tetrahedral element and six truss elements have been derived. Additionally to these unit cells other truss elements are attached representing bundles of muscle fibers and therefore the active part of the material behaviour. The contractile behaviour of the muscle is mainly in.uenced by the stretch of the muscle fibres, the shortening velocity and the activation status of the muscle. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic elasto‐plastic damage formulation for finite strains using a damage structural tensor and the effective stress concept
Authors: Kintzel Olaf , Meschke Günther 
Published: December 2005

AbstractUsing the strain equivalence principle and the effective stress concept an anisotropic finite strain damage model is proposed as a direct extension of the classical isotropic LEMAITRE damage model to the anisotropic finite strain case. The damage tensor is included as a structural tensor in the complementary energy potential. This approach allows to consider a wide range of anisotropic damage phenomena on the level of continuum mechanics. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A composite model for municipal solid waste
Authors: Krase Volker , Dinkler Dieter 
Published: December 2005

AbstractThe mechanical behaviour of municipal solid waste is very complex due to the internal structure and differs considerably from ordinary materials. The fundamental idea of the presented mechanical constitutive model is the split of the material into two solid phases, justified by experimental observations, where fibrous particles signi.cantly influence the composite behaviour. Constitutive laws are independently introduced for each phase. A .nite deformation theory is applied, whereas the concept of elastoplasticity allows reproducing the highly non‐linear stress‐strain relations. A creep law describes time‐depending deformation under compression loads. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanical Approach of Martensitic Transformation Problem in Steels
Authors: Zhang Wenge , Hunkel Martin , Zoch Hans‐Werner 
Published: December 2005

AbstractTo determine the mechanical behavior of material involving the martensitic phase transformation (for example, steels like 100Cr6), a representative volume element (RVE) model including phase transformation criterion is desireable at micromechanical approach. A framework combining the Eshelby's inclusion theory as well as continuum mechanics with phase‐transformation (PT) critical condition at RVE model is presented briefly. And application of this model to estimate the critical aspect ratio of martensitic plate or lath inside homogeneneous stress field is also included, where the RVE can be under uniaxial tension/compression or pure shear loading case. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification and characterization of a “biomarker of toxicity” from the proteome of the paralytic shellfish toxin‐producing dinoflagellate Alexandrium tamarense (Dinophyceae)
Authors: Chan Leo Lai , Sit Wai‐Hung , Lam Paul Kwan‐Sing , Hsieh Dennis Paul Hsientang , Hodgkiss Ivor John , Wan Jennifer Man‐Fan , Ho Alvin Yam‐Tat , Choi Nicola Man‐Chi , Wang Da‐Zhi , Dudgeon David 
Published: December 2005

AbstractThe objective of this study was to identify and characterize a “biomarker of toxicity” from the proteome of Alexandrium tamarense, a paralytic shellfish toxin (PST)‐producing dinoflagellate. A combination of 2‐DE and MS approaches was employed to identify proteins of interest in the vegetative cells of several strains of A. tamarense with different toxin compositions and from different geographical locations. The electrophoretic analysis of the total water‐soluble proteins from these toxic strains by 2‐DE showed that several abundant proteins, namely AT‐T1, AT‐T2 and AT‐T3, differing slightly in apparent Mr and pIs, were consistently present in all toxic strains of A. tamarense. Further analysis by MALDI‐TOF MS and N‐terminal amino acid sequencing revealed that they are isoforms of the same protein. Even more intriguing is that these proteins in A. tamarense have similar amino acid sequences and are closely related to a “biomarker of toxicity” previously reported in A. minutum. Unambiguous and highly species‐specific identification was later achieved by comparing the PMFs of proteins in these two species. An initial attempt to characterize these proteins by generation of murine polyclonal antibodies against the AT‐T1 protein was successful. Western blot analysis using the murine AT‐T1‐polycolonal antibodies identified all the toxic strains of A. tamarense and A. minutum, but not the nontoxic strain of A. tamarense. These results indicate that these protein characteristics for toxic strains are species‐specific and that they are stable properties of the tested algae which are clearly distinguishable irrespective of geographical location and toxin composition. To our knowledge, this is the first study to demonstrate the use of polyclonal antibodies against marker proteins purified from 2‐DE gels to distinguish different strains and species of the PST‐producing dinoflagellate Alexandrium. It provides the basis for the production of monoclonal antibody probes against the “biomarkers of toxicity” for those dinoflagellates whose genome is incompletely characterized. Potentially, immunoassays could be developed to detect the presence of toxic algae in routine monitoring programs as well as to predict bloom development and movement.
A robust meta‐classification strategy for cancer detection from MS data
Authors: Bhanot Gyan , Alexe Gabriela , Venkataraghavan Babu , Levine Arnold J 
Published: December 2005

AbstractWe propose a novel method for phenotype identification involving a stringent noise analysis and filtering procedure followed by combining the results of several machine learning tools to produce a robust predictor. We illustrate our method on SELDI‐TOF MS prostate cancer data (http://home.ccr.cancer.gov/ncifdaproteomics/ppatterns.asp). Our method identified 11 proteomic biomarkers and gave significantly improved predictions over previous analyses with these data. We were able to distinguish cancer from non‐cancer cases with a sensitivity of 90.31% and a specificity of 98.81%. The proposed method can be generalized to multi‐phenotype prediction and other types of data (e.g., microarray data).