bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling and Control of a Hydraulic Actuated Large Scale Manipulator
Authors: Stadlmayr Richard , Schlacher Kurt 
Published: November 2004

AbstractThis contribution deals with the modelling and control of an elastic manipulator. The arm is actuated by a hydraulic ram due to the significant weight. The overall goal is to achieve good tracking of the tip, as well as to reject disturbances, which act on the flexible arm. The controller design is based on two approaches. A flatness‐based feedforward control takes care of the tracking behaviour, and a passivity‐based feedback law stabilizes the trajectories and suppresses the elastic vibrations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design of a nonlinear observer using automatic differentiation
Authors: Winkler Jan , Lindert Sven‐Olaf , Röbenack Klaus , Rudolph Joachim 
Published: November 2004

AbstractObserver design for a class of observable nonlinear systems is considered. By a coordinate transformation and linearization around a desired trajectory the problem is reduced to the design for a linear time varying system. Calculation of the observer gain, depending on the desired trajectory, requires several derivatives. These are calculated using automatic differentiation by a combination of forward and reverse mode. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anwendung eines O(N) Algorithmus auf elastische Mehrkörperketten
Authors: Ferrara Paolo , Bremer Hartmut 
Published: November 2004

AbstractHandhabungs und Fertigungsroboter sind, dam aktuellen Stand der Technik entsprechend, starr gebaut um den hohen Ansprüchen an Genauigkeit und Geschwindigkeit zu genügen. Neuartige Serviceroboter für Haushalts‐ oder Rehabilitationsaufgaben könnten hingegen in Leichtbauweise, elastisch konstruiert werden. Ein häufig angewandtes Regelungskonzept, das einer Vorsteuerung (Inversdynamik) plus Regelung der kleinen restlichen Abweichungen, erfordert ein vollständig beobachtetes System um Modellungenauigkeiten und Störungen bestmöglich zu kompensieren. Sowohl Zustands‐ als auch Störbeobachter werden dabei durch ein realitätsnahes Modell stark vereinfacht, wenn dieses Modell in Echtzeit gelöst und simuliert wird. Jede Abweichung der Realität vom idealen Modell wäre dann als Störgröße interpretierbar. Die Methodik für die Aufstellung solcher, schnell lösbarer, Bewegungsgleichungen (Ordnung N) wurde in [1] beschrieben und wird in dieser Arbeit als Implementierung in Matlab‐Simulink vorgestellt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Micro‐Sphere Model for Rubber Viscoelasticity: A Micromechanically Based Network Model for Polymers.
Authors: Göktepe Serdar , Miehe Christian 
Published: November 2004

AbstractThe micromechanically based non‐affine elastic network model incorporating topological constraints has been recently proposed in Miehe et al. [3]. In the current contribution we advance the micro‐sphere elastic full network model so that it accounts for the rate dependent viscous effects. The viscoelastic network model is constructed by additively dividing the total network response into elastic and viscous parts. The equilibrium response of the material is described by the model proposed in Miehe et al. [3]. The time‐dependent overstress response is based on the two basic mechanisms: the retraction of the unconstrained dangling chains by diffusive reptile motion and the release of constraint effects due to the surrounding chains. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal Analysis of Free‐Corner Effects in Cross‐Ply Plates by a Higher‐Order Theory Approach
Authors: Longeru Markus , Mittelstedt Christian , Becker Wilfried 
Published: November 2004

AbstractStresses in the vicinity of free edges and corners of composite laminates exhibit a distinct localized three‐dimensional behaviour [1] and thus represent an important technical situation. Since numerical analyses of stress concentration phenomena in layered structures are computationally expensive, the present contribution is devoted to a simple closed‐form higher‐order theory approach for the calculation of displacements, strains and stresses in the vicinity of a rectangular corner of symmetric cross‐ply laminates under uniform thermal load ΔT. An appropriate representation for the displacement field in the form of a single‐layer theory with unknown inplane components and appropriately assumed functions through the plate thickness yields closed‐form expressions for the strains and stresses throughout the whole laminate. Equilibrium and boundary conditions are fulfilled in an integral sense. The present approach is easily applied, is of a completely closed‐form analytic nature and requires only little computational effort. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A SimpleModel for Anisotropic Damage with Applications to Soft Tissues
Authors: Balzani Daniel , Schröder Jörg , Gross Dietmar 
Published: November 2004

AbstractArteries are reinforced by helically arranged collagen fibers and posses orthotropic elastic properties. In this paper a polyconvex anisotropic energy is used in order to guarantee the existence of minimizers for the purely elastic boundary value problem. Anisotropic discontinuous damage effects, which are induced by decreasing stiffness of particular fibers, are observed in a certain range of overexpansion. A simple thermodynamical consistent anisotropic damage model is constructed, basing on the assumption that damage mainly takes place in the fiber directions as a result of breakage of collagen cross‐links.Finally a cycled overexpansion of a test material from an artery is analyzed in order to show the main characteristics of the proposed model. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Entwicklung eines 4‐Knoten‐Elements zur Berechnung von Nanostrukturen
Authors: Nasdala Lutz , Ernst Gerald , Rothert Heinrich 
Published: November 2004

AbstractZur Berechnung von Nanostrukturen wie z.B. Kohlenstoff‐Nanoröhren stehen eine Reihe von Kraftfeld‐Ansätzen (force fields) zur Verfügung, die sich aus molekulardynamischen Untersuchungen bzw. quantenmechanischen “ab initio” Berechnungen herleiten lassen. Sie liefern die potentielle Energie einer Struktur in Abhängigkeit von der Art und Anzahl der chemischen und physikalischen Bindungen. Die verschiedenen Energieformen lassen sich grundsätzlich mit nichtlinearen Normalkraft‐, Biegemomenten‐ und Torsionsmomentenfedern vergleichen, so dass der Einsatz von Finite Elemente Programmen nahe liegt. Aufgrund der Interaktion mehrerer Atome und der Tatsache, dass Atome keine Rotationsfreiheitsgrade im mechanischen Sinne besitzen, ist die Anwendung von Standard‐Elementen wie Stab‐, Balken‐ oder Schalenelementen problematisch. Beispielsweise führt die Verdrehung von Balkenelementen zu unerwünschten Zwängungen in angrenzenden Molekülgruppen. Aus diesem Grund wird eine neues 4‐Knoten‐Element entwickelt, das ausschließlich Verschiebungen als Freiheitsgrade benutzt und somit in der Lage ist, die verschiedenen Energieformen exakt abzubilden. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐Mechanical Modelling of the Constitutive Behaviour of NiTi Shape Memory Alloys
Authors: Zhang Wenge , Hackl Klaus , Hoppe Ulrich 
Published: November 2004

AbstractThe superelasticity and shape memory effect in NiTi alloys are examined on the basis of micromechanics within the energy minimization framework. We describe the behaviour of polycrystalline shape‐memory alloys via orientation‐distribution of the various martensite‐variants (domains) present in the material. Stress‐strain curves are presented and special attention is payed to the volume fraction of martensite for specific NiTi alloys (Nitinol) specimen under uniaxial tension. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved prenatal detection of a fetal point mutation for achondroplasia by the use of size‐fractionated circulatory DNA in maternal plasma—case report
Authors: Li Y. , Holzgreve W. , Page‐Christiaens G. C. M. L. , Gille J. J. P. , Hahn S. 
Published: November 2004

AbstractIntroductionThe efficacious analysis of fetal loci involving point mutations from circulatory fetal DNA in maternal plasma is hindered by the preponderance of maternal DNA. It has recently been shown that the size difference between fetal and maternal DNA species can be used for the selective enrichment of circulatory fetal DNA in maternal plasma. We have now tested this approach for the detection of a fetal point mutation in the fibroblast growth factor receptor 3 (FGFR3) gene that causes achondroplasia.MethodsCirculatory DNA was extracted from maternal plasma and size‐fractionated by agarose gel electrophoresis. The fraction with a size less than 300 bp was examined by a touchdown PCR assay specific for the FGFR3 gene, and the mutation was identified by SfcI restriction analysis.ResultOur analysis indicated that although the fetal mutation was discernible in the analysis of total plasma DNA, the result using size‐fractionated DNA was much more evident.ConclusionThe enrichment of circulatory fetal DNA in maternal plasma by size‐fractionation facilitates the detection of subtle feto‐maternal genetic differences, such as those involving point mutations. This approach can easily be extended for the non‐invasive prenatal determination of other fetal loci. (190) Copyright © 2004 John Wiley & Sons, Ltd.
Cost‐effectiveness of prenatal screening for thalassaemia in Hong Kong
Authors: Leung K. Y. , Lee C. P. , Tang M. H. Y. , Lau E. T. , Ng L. K. L. , Lee Y. P. , Chan H. Y. , Ma E. S. K. , Chan Vivian 
Published: November 2004

AbstractObjectivesTo determine the cost effectiveness of a universal prenatal screening program for α‐ and β‐thalassaemia.MethodsWe retrospectively reviewed our program from 1998 to 2002, and calculated the direct and indirect costs of various components.Results18 936 women were screened at our prenatal clinic and 153 couples were subsequently referred to our Prenatal Diagnostic Centre for counselling and further investigations. In addition, there were 238 tertiary referrals and 157 self‐referrals. After investigations, 84 fetuses were at risk of β‐thalassaemia major/β‐E thalassaemia, 19 of them were affected and 18 were aborted. The total expenditure on our program (HK$10.0 million) would be less than the postnatal service costs (HK$40.4 million) for 18β‐thalassaemia major fetuses if they were born. Of 361 women at risk of carrying a homozygous α0‐thalassaemia fetus, 311 (86.2%) opted for the indirect approach (using serial ultrasound examinations to exclude Hb Bart's disease), and 76 (24.5%) subsequently underwent an invasive test for a definitive diagnosis. The sensitivity and false positive rate of this indirect approach was 100.0% and 2.9% respectively.ConclusionIt is cost effective to run a universal prenatal screening program in an area where both β‐thalassaemia and α‐thalassaemia are prevalent. The indirect approach can effectively avoid an invasive test in unaffected pregnancies. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal diagnosis of deletion of chromosome 6p presenting with hydrops fetalis
Authors: Suwanrath‐Kengpol Chitkasaem , Limprasert Pornprot , Mitarnun Winyou 
Published: November 2004

AbstractObjectiveTo report the first known case of 6p deletion presenting in utero with hydrops fetalis and multiple anomalies in the second trimester of pregnancy.MethodsA thirty‐year‐old woman (gravida 3 para 1 abortion 1) was referred to our hospital at 18 weeks of gestation because of suspicion of fetal anomaly on routine ultrasound examination. A detailed anomaly scan revealed a single viable fetus with marked skin edema, marked ascites, pleural effusion, hydronephrosis of left kidney, absence of right kidney, cardiac anomaly and oligohydramnios. The fetal face was not visible due to the fetal position. Fetal karyotyping revealed 46,XX,del(6)(p21.3). The couple opted to terminate the pregnancy.ResultsA hydropic female fetus was aborted and the autopsy revealed hydrops fetalis with bilateral cleft lips, hydronephrosis of left kidney, absence of right kidney, spleen, and thymus gland, truncus arteriosus, and single umbilical artery. Cord blood and tissue culture confirmed that the fetus had deletion of chromosome 6p.ConclusionDeletion of short arm of chromosome 6 can result in hydrops fetalis in early pregnancy. Copyright © 2004 John Wiley & Sons, Ltd.
Termination of pregnancy: attitudes and behavior of women in a traditional society
Authors: Shoham‐Vardi I. , Weiner N. , Weitzman D. , Levcovich A. 
Published: November 2004

AbstractObjectivesThe Bedouin Arabs, a Muslim traditional ethnic minority in Israel, are faced with difficult choices when offered prenatal diagnosis as part of the universally provided prenatal care in Israel. This paper is to examine attitudes towards and practice of pregnancy termination, following an unfavorable prenatal diagnosis.MethodsSemistructured interviews with 83 women were conducted to study attitudes. Data from the Soroka Medical Center, where all births in the area take place, were used to assess the rate of terminations of pregnancies following a diagnosis of a chromosomal anomaly.ResultsWhile divided on the question of termination, many women believed that a second medical opinion is needed, preferably from an Arab physician. The reasons for termination are both child‐ and mother‐related. Opposing termination is based on both the suspicion that the diagnosis might be wrong and on religious reasons. Between 1995 and 1999, 686 Bedouin women had undergone amniocentesis (2.4% of all pregnancies). Six of 11 pregnancies with the diagnosis of a trisomy were terminated (54.5%). All cases in which a trisomy was terminated were trisomy 21.ConclusionsCulturally acceptable prenatal diagnostic services for Muslim populations should be based on early testing, and should involve Muslim physicians and religious authorities. Copyright © 2004 John Wiley & Sons, Ltd.
Morphology and mechanical properties of injection molded poly(ethylene terephthalate)
Authors: Viana Júlio C. , Alves Natália M. , Mano João F. 
Published: November 2004

AbstractThis work reports on the relationships between processing, the morphology and the mechanical properties of an injection molded poly(ethylene terephthalate), PET. Specimens were injection molded with different mold temperatures of 30°C, 50°C, 80°C, 100°C, 120°C, 150°C, while maintaining constant the other operative processing parameters. The thermomechanical environment imposed during processing was estimated by computer simulations of the mold‐filling phase, which allow the calculation of two thermomechanical indices indicative of morphological development (degree of crystallinity and level of molecular orientation). The morphology of the moldings was characterized by differential scanning calorimetry (DSC) and by hot recoverable strain tests. The mechanical behavior was assessed in tensile testing at 5 mm/min and 23°C. A strong thermal and mechanical coupling is evidenced in the injection molding process, significantly influencing morphology development. An increase in the mold temperature induces a decrease of the level of molecular orientation (decrement in the hot recoverable strain) and an increment in the initial crystallinity of the moldings (decrement in the enthalpy of cold crystallization), also reflected in the variations of the computed thermomechanical indices. The initial modulus is mainly dependent upon the level of molecular orientation. The yield stress is influenced by both the degree of crystallinity and the level of molecular orientation of the moldings, but more significantly by the former. The strain at break was not satisfactorily linked directly to the initial morphological state because of the expected morphology changes occurring during deformation. Polym. Eng. Sci. 44:2174–2184, 2004. © 2004 Society of Plastics Engineers.
Isothermal and nonisothermal crystallization kinetics of syndiotactic polystyrene/clay nanocomposites
Authors: Wu Tzong‐Ming , Hsu Sung‐Fu , Chien Cheng‐Fung , Wu Jeng‐Yue 
Published: November 2004

AbstractDifferential scanning calorimeter (DSC) and X‐ray diffraction methods were used to investigate the isothermal and nonisothermal crystallization behavior and crystalline structure of syndiotactic polystyrene (sPS)/clay nanocomposites. The sPS/clay nanocomposites were prepared by mixing the sPS polymer solution with the organically modified montmorillonite. DSC isothermal results revealed that introducing 5 wt% of clay into the sPS structure causes strongly heterogeneous nucleation, inducing a change of the crystal growth process from mixed three‐dimensional and two‐dimensional crystal growth to two‐dimensional spherulitic growth. The activation energy of sPS drastically decreases with the presence of 0.5 wt% clay and then increases with increasing clay content. The result indicates that the addition of clay into sPS induces the heterogeneous nucleation (a lower ΔE) at lower clay content and then reduces the transportation ability of polymer chains during crystallization processes at higher clay content (a higher ΔE). We studied the non‐isothermal melt‐crystallization kinetics and melting behavior of sPS/clay nanocomposites at various cooling rates. The correlation among crystallization kinetics, melting behavior and crystalline structure of sPS/clay nanocomposites is discussed. Polym. Eng. Sci. 44:2288–2297, 2004. © 2004 Society of Plastics Engineers.
Temperature control of injection molding. Part I: Modeling and identification
Authors: Diduch Chris , Dubay Rickey , Li Wan Gui 
Published: November 2004

AbstractThis paper develops a mathematical model for the dynamics of a plastic injection molding machine (IMM) that may be used for the design of a temperature‐control system. The research in this paper is novel in comparison to others since the derived models explicitly include the effects of zone interaction and backpressure, and do not lump these into an arbitrary disturbance signal. A series of experiments were conducted on a 150‐tonne IMM to identify the parameters of the proposed model using measurements of zone temperatures, percentage heater input, backpressure and screw speed. The identified model was validated using a series of blind tests that compared the model output with the measured barrel temperatures of the IMM. Polym. Eng. Sci. 44:2308–2317, 2004. © 2004 Society of Plastics Engineers.
The effect of molding conditions on mechanical and morphological properties at the interface of film insert injection molded polypropylene‐film/polypropylene matrix
Authors: Leong Y. W. , Yamaguchi S. , Mizoguchi M. , Hamada H. , Ishiaku U. S. , Tsujii T. 
Published: November 2004

AbstractAn extensive study on the peel strength between a polypropylene (PP) film and PP substrate fabricated using film insert injection molding technique was carried out through a 180° peel test. Injection molding conditions such as barrel temperature, injection speed and holding pressure were varied to gauge their effects on the mechanical and morphological properties. Morphological observations were made at the film‐substrate interfacial regions by means of transmission electron microscopy (TEM). The injection molded products, with the films still attached, were subjected to bending and impact tests to determine if there is any relationship between film‐substrate adhesion and bulk properties. Observation of the load‐displacement curves during the peel test revealed three unique and interesting curves, corresponding to different peeling and film fracture mechanisms. Increases in injection speed, barrel temperature and holding pressure lead to increased bonding between the film and substrate surfaces. The enhancement of bonding between these two polymer surfaces could be attributed to polymer‐polymer interdiffusion. Substantiating evidence from TEM, which shows the fading of the interface as the bond strengthens, further boosts the accuracy of this assumption. The hope that the films could contribute to enhancing bulk properties has been diminished since the bending properties appeared to be similar with or without the film attached. Polym. Eng. Sci. 44:2327–2334, 2004. © 2004 Society of Plastics Engineers.
Automatic mass spectrometry method development for drug discovery: application in metabolic stability assays
Authors: Chovan Linda E. , Black‐Schaefer Candace , Dandliker Peter J. , Lau Yau Yi 
Published: November 2004

AbstractHigh‐throughput metabolic screening has been requested routinely to keep pace with high‐throughput organic synthesis. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a fast gradient has become the method of choice for the task due to its sensitivity and selectivity. We have developed an automated system that consists of a robotic system for in vitro incubation and a commercially available software package for automatic MS/MS method development. A short, generic LC gradient and MS conditions that are applicable to most compounds have been developed to minimize the method development time and data analysis. This system has been used to support a number of in vitro screening assays in early drug discovery phase including microsomal stability and protein binding. Copyright © 2004 John Wiley & Sons, Ltd.
Kommentare zur DIN EN14015
Authors: Bußhaus Ludger 
Published: November 2004

AbstractZur neuen europäischen Anwendungsnorm für Flachbodentanks DIN EN 14015 wird kein offizieller Kommentar vom CEN/TC 265 herausgegeben. Deshalb sollen die nachstehenden Kommentare den Anwender auf kritische Punkte hinweisen, die eigentlich alle in einem Nationalen Vorwort hätten aufgeführt werden sollen.
Bax‐induced cell death in Candida albicans
Authors: De Smet Kris , Eberhardt Ines , Reekmans Rieka , Contreras Roland 
Published: November 2004

AbstractBax is a pro‐apoptotic member of the Bcl‐2 family of proteins involved in the regulation of genetically programmed cell death in mammalian cells. It has been shown that heterologous expression of Bax in several yeast species, such as Saccharomyces cerevisiae, Schizosaccharomyces pombe and Pichia pastoris, also induces cell death. In this study we investigated the effects of Bax expression in the pathogenic yeast Candida albicans. Cell death inducing expression of Bax required a synthetic BAX gene that was codon‐optimized for expression in Candida albicans. Expression of this BAX gene resulted in growth inhibition and cell death. By fusing Bax with the yeast enhanced green fluorescent protein of Aequoria victoria, the cell death‐inducing effect of Bax was increased due to reduced proteolytic degradation of Bax. Using this fusion protein we showed that, upon expression in C. albicans, Bax co‐localizes with the mitochondria. Furthermore, we showed for the first time that expression of Bax in yeast causes the mitochondria, which are normally distributed throughout the cell, to cluster in the perinuclear region. Copyright © 2004 John Wiley & Sons, Ltd.