bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rolling contact between agricultural tire and deformable ground
Authors: Wille R. , Böhm F. , Duda A. 
Published: November 2004

AbstractWhile external tire mechanics deals with the effect of tires on vehicle behaviour, internal tire mechanics is focused on computation of stress‐strain and heat states in a tire. Analytical and numerical analysis of different level tire substructure is a pre‐condition for a better understanding of tire behaviour and for a suitable choice of practical calculation schemes. The tire is described geometrically non‐linear as a multi‐layered anisotropic torus shell with low transfer shear stiffness. The strains are assumed to be small, however, the cross‐sections of the tire shell will exhibit moderate rotations. In order to reflect energy losses the visco‐elastic behaviour of tire rubber‐cord‐composite is taken into account. Results are used for the determination and improvement of stiffness parameters for external tire models and for Böhm's mass points approach for transient loading of a rolling tire on rigid and deformable ground. This model is modified to the real structure of an agricultural tire with lugs. The soil under the tire is described by different rheological laws of ground surface behaviour in normal and tangential direction. The numerical results of contact calculation are compared with experimental data gained by mechanical multi‐point measurement technique in order to determine the displacements in the inner of a rolling tire. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Computation of Anisotropically Evolving Yield Surfaces Based on Micro‐to‐Macro Transitions
Authors: Gürses Ercan , Becker Martin , Miehe Christian 
Published: November 2004

AbstractThe paper proposes a numerical computation technique for anisotropically evolving yield surfaces based on micro–to–macro transitions. The underlying model of the finite crystal plasticity and the homogenization approach have previously been formulated by Miehe et al. [2]. The technique proposed has the following two central aspects, firstly a criterion for the determination of the macroscopic yield point is introduced which is based on the physically relevant mechanisms on the microscale and secondly, as a key point of the methodology, total unloading is applied to the representative volume element (RVE) before the yield surface for the corresponding microstructure is determined. The explained method is applied to a Taylor type polycrystalline material model. With respect to the validation of the proposed concept different tests are performed for various preloading conditions and comparisons with experimental findings are provided. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of the filler volume fraction on the mechanical behaviour of thermoplastic materials
Authors: Kletschkowski Thomas , Schomburg Uwe , Betram Albrecht 
Published: November 2004

AbstractUniaxial experiments clarify that the mechanical behaviour of PTFE compounds depends strongly on the amount of filler particles. In order to describe these dependencies, a finite endochronic viscoplastic material model based on material isomorphisms has been applied to various glass fibre filled PTFE compounds. The model allows to characterize viscoplastic material behaviour with equilibrium hysteresis using a rate‐independent endochronic elastoplastic model in parallel connection with a nonlinear Maxwell model. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ein phänomenologisches Modell für anisotropes Kriechen in Schweißnähten
Authors: Naumenko Konstantin , Altenbach Holm 
Published: November 2004

AbstractDie Auswertung von experimentellen Ergebnissen für Zugproben, die an unterschiedlichen Stellen in Schweißnähten entnommen wurden, haben gezeigt, dass das entsprechende Kriechverhalten anisotrop ist. Nachfolgend werden erste Überlegungen zur phänomenologischen Modellierung und Simulation vorgestellt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Eulerian‐Lagrangian Concept for the Numerical Simulation of Flat Steady‐State Hot Rolling Processes
Authors: Synka Josef , Kainz Alexander 
Published: November 2004

AbstractFor the finite element analysis of stationary flat hot rolling processes, a new and efficient mathematical model was developed. The method is based on an intermediary Eulerian‐Lagrangian concept, where an Eulerian coordinate is employed in the rolling direction, while Lagrangian coordinates are used in the direction of the thickness and width of the strip. This approach yields an efficient algorithm, where the time is eliminated as an independent variable in the steady‐state case. Further, the vector of independent field variables consists of a velocity component in Eulerian and of displacement components in Lagrangian directions. Due to this concept, the free surface deformations can be accounted for directly and the problems encountered with pure Eulerian or Lagrangian models now appear with reduced complexity and can thus be tackled more easily. The general formalism was applied to different practical hot rolling situations, ranging from thick slabs to ultra‐thin hot strips. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An algorithm for shakedown analysis of structures with temperature dependent yield stress
Authors: Vu Duc Khoi , Staat Manfred 
Published: November 2004

AbstractThis work is an attempt to answer the question: How to use convex programming in shakedown analysis of structures made of materials with temperature‐dependent properties. Based on recently established shakedown theorems and formulations, a dual relationship between upper and lower bounds of the shakedown limit load is found, an algorithm for shakedown analysis is proposed. While the original problem is neither convex nor concave, the algorithm presented here has the advantage of employing convex programming tools. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Model for Kidney Tissue Damage under High Speed Loading
Authors: Weinberg Kerstin , Colonius Tim , Ortiz Michael 
Published: November 2004

AbstractIn a medical procedure to comminute kidney stones the patient is subjected to hypersonic waves focused at the stone. Unfortunately such shock waves also damage the surrounding kidney tissue. We present here a model for the mechanical response of the soft tissue to such a high speed loading regime.The material model combines shear induced plasticity with irreversible volumetric expansion as induced, e.g., by cavitating bubbles. The theory is based on a multiplicative decomposition of the deformation gradient and on an internal variable formulation of continuum thermodynamics. By the use of logarithmic and exponential mappings the stress update algorithms are extended from small‐strain to the finite deformation range. In that way the time‐discretized version of the porous‐viscoplastic constitutive updates is described in a fully variational manner.By numerical experiments we study the shock‐wave propagation into the tissue and analyze the resulting stress states. A first finite element simulation shows localized damage in the human kidney. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Stress Adaptive Bone Remodelling – Towards an IndividualTherapy in Endoprosthetics –
Authors: Ebbecke Bastian , Nackenhorst Udo 
Published: November 2004

AbstractComputational techniques for the simulation of stress‐adaptive bone‐remodelling have been developed and applied for the analysis of the bio‐mechanical compatibility of hip‐joint endoprosthesis. Numerical simulations are in good agreement with clinical observations and enable parameter studies for the development of optimized prosthesis designs. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling the Intervertebral Disc – A Biomechanical Challenge
Authors: Markert Bernd , Ehlers Wolfgang , Karajan Nils 
Published: November 2004

AbstractFrom a microscopic perspective, the intervertebral disc (IVD) as a soft biological tissue is a complex arrangement of mostly ionized water and collagen fibers embedded in a charged extracellular meshwork of protein compounds. The difficulty of describing the physiological properties of the disc on the macroscale lies in the strong interaction of all components contributing to the inhomogeneous tissue micro structure. Therefore, an appropriate macroscopic approach must account for a fiber‐reinforced porous solid, which is saturated by a free movable interstitial fluid. In addition to the solid‐fluid interaction, electrostatic and osmotic effects as well as the intrinsic viscoelasticity of the extracellular matrix must be considered. All these requirements are consistently realized within the well‐founded framework of the Theory of Porous Media (TPM), which moreover enables efficient large strain analyses based on the finite element method (FEM). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uptake of a prenatal screening test: the role of healthcare professionals' attitudes towards the test
Authors: Dormandy Elizabeth , Marteau Theresa M. 
Published: November 2004

AbstractObjectiveTo investigate the association between healthcare professionals' attitudes towards prenatal Down syndrome screening and screening uptake in the women who consult them.MethodsThe attitudes of 71 midwives and 18 obstetricians towards Down syndrome screening and screening uptake in the women who consulted them were assessed at two UK hospitals where uptake rates of Down syndrome screening differed (26 vs 61%).ResultsHealthcare professionals based at the hospital with higher screening uptake had more positive attitudes towards Down syndrome screening than healthcare professionals based at the hospital with lower screening uptake (19 vs 17, p = 0.03). Pooling across hospitals, obstetricians had more positive attitudes than midwives (20 vs 17, p = 0.004). In a sub‐group of women who discussed screening with one healthcare professional, there was no significant association between individual healthcare professionals' attitudes and screening uptake (Spearman correlation coefficient = 0.13, p = 0.51).ConclusionIn this study powered to detect a correlation of 0.5 and over (i.e. a large effect), healthcare professionals' attitudes towards screening were unrelated to uptake of screening in the women consulting them. It remains to be determined if a smaller effect exists. The observed association between healthcare professionals' attitudes and uptake rates by hospitals raises the question of whether healthcare professionals' attitudes might influence systems of care, not just communication with pregnant women. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative analysis of cellular fetal hemoglobin gamma chain messenger RNA (HbF‐γ mRNA) in maternal peripheral blood
Authors: Okuda Tomohiro , Kinoshita Yoshiyuki , Tamura Takaya , Kato Chikako , Kojima Hidenori , Watanabe Ai , Honjo Hideo 
Published: November 2004

AbstractObjectiveFetal cells cross the feto‐maternal barrier and circulate in maternal peripheral blood; thus, this study aimed to show the relationship between clinical evidence in pregnancy and qualitative feto‐maternal barrier changes.MethodsThe expression of fetal hemoglobin gamma chain messenger RNA (HbF‐γ mRNA) was measured by quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) in maternal peripheral blood.ResultsHbF‐γ mRNA was detected in all pregnant women after 5 weeks of gestation. In normal pregnancy, there were two peaks at 10 and 40 weeks, and a significant increase 4 weeks prior to the onset of labor. In intrauterine growth restriction (IUGR), preterm delivery and placenta previa, the HbF‐γ mRNA expression was significantly higher than in normal pregnancies.ConclusionThe expression of HbF‐γ mRNA relative to that of β‐actin mRNA is thought to reflect the real‐time leakage of fetal cells into maternal blood. Copyright © 2004 John Wiley & Sons, Ltd.
Current awareness in prenatal diagnosis
Authors:   John Wiley & Sons, Ltd.
Published: November 2004

AbstractIn order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of prenatal diagnosis. Each bibliography is divided into 17 sections: 1 Books, Reviews & Symposia; 2 General Interest; 3 Normal Fetal Development; 4 Gametogenesis and Pre‐implantation Diagnosis; 5 First Trimester Diagnosis; 6 Second Trimester Diagnosis; 7 Fetal Diagnosis by Ultrasound and Other Imaging; 8 Maternal Screening; 9 Screening for Carriers of Genetic Abnormality; 10 Technological Developments; 11 Confined Placental Mosaicism and Uniparental Disomy; 12 Molecular Cytogenetics; 13 Fetal Cells in Maternal Circulation; 14 Fetal Therapy; 15 Psychosocial Aspects; 16 Epidemiology and Environmental Factors; 17 Developmental Pathology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted
Polymer crystallization kinetics, master quotients, master curves and Nakamura‐Ozawa‐equations of iPP and PTFE
Authors: Lambrigger Markus 
Published: November 2004

AbstractEvaluation concepts related to Avrami master curves are described for the analysis of isothermal and non‐isothermal kinetic processes exhibiting topological nucleation and growth characteristics. These evaluation concepts are shown to be helpful for studies focusing on kinetic data of polymer crystallization experiments with iPP (isotactic polypropylene) and PTFE (polytetrafluoroethylene). An apparent m‐order reaction model is discussed with respect to the isokinetic nucleation and growth model of Nakamura as well as to the non‐isothermal crystallization kinetics theory of Ozawa. Thus, the cooling functions χ(T) of iPP and PTFE, obtained by analyzing DSC (differential scanning calorimetry) experiments with constant cooling rates, are calculated in two alternative ways by using clearly different mathematical approaches. Finally, master quotients, theoretical crystallization limits, and further types of master curves are defined. Polym. Eng. Sci. 44:2194–2202, 2004. © 2004 Society of Plastics Engineers.
Fate of erucamide in polyolefin films at elevated temperature
Authors: Shuler Christopher A. , Janorkar Amol V. , Hirt Douglas E. 
Published: November 2004

AbstractErucamide is incorporated into polymer films to reduce their coefficient of friction (COF). At elevated temperatures, erucamide may be lost from the film surface to the surroundings, undergo chemical change or decomposition, and/or migrate back into the film. The major objective of this work was to investigate the fate of erucamide upon exposure to a higher temperature (55°C). Trilayer films containing a polyolefin plastomer (POP) as one skin layer and LLDPE as the other two layers with erucamide incorporated in the POP layer were used. Based on ATR‐FTIR spectroscopy, solvent washing, and GC‐MS results it was concluded that, upon exposure to 55°C, the major reduction in erucamide surface concentration was due to migration of erucamide back into the film and a slight reduction was due to the decomposition of erucamide present on the surface of the polymer film. Polym. Eng. Sci. 44:2247–2253, 2004. © 2004 Society of Plastics Engineers.
Experimental studies on radial extrudate swell and velocity profiles of flowing PS melt in an electro‐magnetized die of an extrusion rheometer
Authors: Intawong N‐T. , Sombatsompop N. 
Published: November 2004

AbstractThis article investigates the radial extrudate swell and velocity profiles of polystyrene melt in a capillary die of a constant shear‐rate extrusion rheometer, using a parallel coextrusion technique. An electro‐magnetized capillary die was used to monitor the changes in the radial extrudate swell profiles of the melt, which is relatively novel in polymer processing. The magnetic flux density applied to the capillary die was varied in a parallel direction to the melt flow, and all tests were performed under the critical condition at which sharkskin and melt fracture did not occur in the normal die. The experimental results suggest that the overall extrudate swell for all shear rates increased with increasing magnetic flux density to a maximum value and then decreased at higher densities. The maximum swelling peak of the melt appeared to shift to higher magnetic flux density, and the value of the maximum swell decreased with increasing wall shear rate and die temperature. The effect of magnetic torque on the extrudate swell ratio of PS melt was more pronounced when extruding the melt at low shear rates and low die temperatures. For radial extrudate swell and velocity profiles, the radial swell ratio for a given shear rate decreased with increasing r/R position. There were two regions where the changes in the extrudate swell ratio across the die diameter were obvious with changing magnetic torque and shear rate, one around the duct center and the other around r/R of 0.65–0.85. The changes in the extrudate swell profiles across the die diameter were associated with, and can be explained using, the melt velocity profiles generated during the flow. In summary, the changes in the overall extrudate swell ratio of PS melt in a capillary die were influenced more by the swelling of the melt around the center of the die. Polym. Eng. Sci. 44:2298–2307, 2004. © 2004 Society of Plastics Engineers.
Studies on impact‐modified nylon 6/ABS blends
Authors: Chiu H. T. , Hsiao Y. K. 
Published: November 2004

AbstractThe objective of this research is to study the effect of using maleic anhydride‐grafted polyethylene‐octene elastomer (POE‐g‐MA) as a compatibilizer on nylon 6/acrylonitile‐butadiene‐styrene (ABS) copolymer blends. With POE‐g‐MA, nylon 6/ABS at a blending ratio of 80/20 showed an optimal result in modified impact property. Scanning electron microscopy (SEM) revealed that the particle sizes of ABS in the dispersed phase diminished as the amount of the added compatibilizer (POE‐g‐MA) increased. The compatibilizer reduced the surface tension between nylon 6 and ABS, thus increasing the compatibility of the two phases. Furthermore, studies of the rheological behavior of the system showed that the shear viscosity of nylon 6/ABS blends also increased with the introduction of POE‐g‐MA. Finally, dynamic mechanical analysis (DMA) experiments showed that adding POE‐g‐MA dramatically improved the impact strength of the blends at room temperature and low temperatures. Polym. Eng. Sci. 44:2340–2345, 2004. © 2004 Society of Plastics Engineers.
Development of an ion mobility spectrometer for use in an atmospheric pressure ionization ion mobility spectrometer/mass spectrometer instrument for fast screening analysis
Authors: Sysoev Alexey , Adamov Alexey , Viidanoja Jyrki , Ketola Raimo A. , Kostiainen Risto , Kotiaho Tapio 
Published: November 2004

AbstractAn ion mobility spectrometer that can easily be installed as an intermediate component between a commercial triple‐quadrupole mass spectrometer and its original atmospheric pressure ionization (API) sources was developed. The curtain gas from the mass spectrometer is also used as the ion mobility spectrometer drift gas. The design of the ion mobility spectrometer allows reasonably fast installation (about 1 h), and thus the ion mobility spectrometer can be considered as an accessory of the mass spectrometer. The ion mobility spectrometer module can also be used as an independently operated device when equipped with a Faraday cup detector. The drift tube of the ion mobility spectrometer module consists of inlet, desolvation, drift, and extraction regions. The desolvation, drift and extraction regions are separated by ion gates. The inlet region has the shape of a stainless steel cup equipped with a small orifice. Ion mobility spectrometer drift gas is introduced through a curtain gas line from an original flange of the mass spectrometer. After passing through the drift tube, the drift gas serves as a curtain gas for the ion‐sampling orifice of the ion mobility spectrometer before entering the ion source. Counterflow of the drift gas improves evaporation of the solvent from the electrosprayed sample. Drift gas is pumped away from the ion source through the original exhaust orifice of the ion source. Initial characterization of the ion mobility spectrometer device includes determination of resolving power values for a selected set of test compounds, separation of a simple mixture, and comparison of the sensitivity of the electrospray ionization ion mobility spectrometry/mass spectrometry (ESI‐IMS/MS) mode with that of the ESI‐MS mode. A resolving power of 80 was measured for 2,6‐di‐tert‐butylpyridine in a 333 V/cm drift field at room temperature and with a 0.2 ms ion gate opening time. The resolving power was shown to be dependent on drift gas flow rate for all studied ion gate opening times. Resolving power improved as the drift gas flow increased, e.g. at a 0.5 ms gate opening time, a resolving power of 31 was obtained with a 0.65 L/min flow rate and 47 with a 1.3 L/min flow rate for tetrabutylammonium iodide. The measured limits of detection with ESI‐MS and with ESI‐IMS/MS modes were similar, demonstrating that signal losses in the IMS device are minimal when it is operated in a continuous flow mode. Based on these preliminary results, the IMS/MS instrument is anticipated to have potential for fast screening analysis that can be applied, for example, in environmental and drug analysis. Copyright © 2004 John Wiley & Sons, Ltd.
Single‐drop microextraction and gas chromatography/mass spectrometric determination of anisaldehyde isomers in human urine and blood serum
Authors: Liu BoMin , Malik Pridap , Wu Hui‐Fen 
Published: November 2004

AbstractThe original article to which this Erratum refers was published in Rapid Commun. Mass Spectrom. 2004; 18: 2059–2064
Ermüdungsverhalten von Mobilkranbauteilen aus hochfesten Baustählen
Authors: Bleck Wolfgang , Hummel Hubert , Kern Andreas , Schriever Udo 
Published: November 2004

AbstractHochfeste Baustähle mit 960 bzw. 1100 MPa Mindeststreckgrenze ermöglichen durch Leichtbauweise eine Verringerung der Investitions‐ und Betriebskosten von Mobilkranen. Bei der Bemessung von Kranen mit diesen Stählen besteht für die zyklische Belastung jedoch große Unsicherheit hinsichtlich ertragbarer Spannungen und der Lebensdauer bei wichtigen Kranbauteilen.In dieser Arbeit wurde erstmalig das Betriebsfestigkeitsverhaltens von Kranbauteilen unter realistischen Belastungs‐Zeit‐Zyklen aus dem Kranbetrieb untersucht. Die Ergebnisse liefern hierzu wichtige Informationen, wonach die Lebensdauer auch bei hohen angewendeten Spannungen wenigstens 20 Jahre für beide untersuchten Stähle beträgt. Es wird gezeigt, daß weitere Verbesserungen der Betriebsfestigkeit um bis zu 50% durch Nachbehandlung der Schweißnähte, Zähigkeitsverbesserung des Grundwerkstoffes und konstruktive Umgestaltung der Bauteile möglich sind.Mittels auf der Bruchmechanik basierenden Rechenmodellen wird in der vorliegenden Arbeit ein neues Werkzeug bereitgestellt, mit dem das Betriebsfestigkeitsverhalten von Kranbauteilen unter verschiedenen Aspekten und Einflußgrößenkombinationen in Übereinstimmung zu gemessenen Werten abgeschätzt werden kann.Für die Praxis können wichtige Handlungsempfehlungen und Hinweise für den verstärkten Einsatz und die Ausnutzung hochfester Baustähle im Mobilkranbau gegeben werden. Inspektionsintervalle und ‐inhalte können neu festgelegt werden.