bluuebunny/crossref_metadata_2025_split huggingface dataset:
Praxisrelevante Bewertung des Radbruchs vom ICE 884 in Eschede
Authors: Fischer G. , Grubisic V. 
Published: October 2007

AbstractDer Unfall des ICE 884 am 3. Juni 1998 bei Eschede wurde infolge eines Bruchs des Radreifens eines gummigefederten Rades Bauart BA 64 nach einer Laufstrecke von 1.889 Mill. km ausgelöst. Der Bruch ging von der Radreifeninnenseite bei einem Laufkreisdurchmesser von DA = 862 mm (neu: DA = 920 mm) aus.Nach dem Unfall wurden viele Analysen und Untersuchungen vorgenommen, die verschiedene Aspekte der Bruchentstehung behandelten. Als Ergebnis dieser Analysen ergab sich, dass der Unfall durch einen Ermüdungsbruch des Radreifens hervorgerufen wurde. Dafür war die den Betriebsbelastungen nicht entsprechende konstruktive Auslegung des Rades und die Bemessung des Radreifens ausschlaggebend. Als untere zulässige Grenze der Radreifendicke wurde ein Radreifendurchmesser von DA = 880 mm für den vorgesehenen Betriebseinsatz ermittelt, der beträchtlich oberhalb des vorgesehenen Betriebsgrenzmaßes von DA = 854 mm lag. Damit ist auch ein Totalbruch des Radreifens mit einem Durchmesser DA = 862 mm erklärlich, was durch Befunde an anderen gummigefederten Rädern von ICE 1 Zügen bestätigt wird.Die vor der Einführung der Räder BA 64 durchgeführten Versuche waren nicht geeignet, die Sicherheit dieser Räder für den vorgesehenen Betriebseinsatz zu gewährleisten.
Integration von Verwertungsstrategien in die Materialforschung – Modellwerkstoffe in der Medizin
Authors: Harraß M. , Strübbe K. , Friedrich K. , Schlarb A. K. , Ensthaler J. , Quirrenbach T. , Bärmann M. , Stasche N. 
Published: October 2007

AbstractBefindet sich ein Unternehmen in einem Entwicklungsprozess, stellt sich regelmäßig die Frage nach den Verwertungsmöglichkeiten. Von besonderer Bedeutung ist dabei die Entscheidung, welche Produkteigenschaften am gewinnbringendsten vermarktet werden können. Schafft man es, die noch im Entwicklungsprozess befindliche Technologie frühzeitig auf betriebswirtschaftliche sowie rechtliche Risiken und Chancen zu bewerten, können diese Erkenntnisse kosteneffizient in der laufenden Forschungsplanung und ‐steuerung berücksichtigt werden. Damit sollen Verwertungsmöglichkeiten berücksichtigt sowie Rentabilität und Gewinnaussichten abgeschätzt werden. Man bedient sich hierbei einzelner Instrumente der Patent‐ und Erfindungsbewertung.Im vorliegenden Aufsatz wird die Integration von Verwertungsstrategien in der Produktentwicklung im Bereich der Medizintechnik vorgestellt. Am Beispiel der Entwicklung eines interventionsfähigen Kehlkopf‐Modells zur laserchirurgischen Fachausbildung werden technische, betriebswirtschaftliche und rechtliche Bewertungsaspekte zusammengeführt.
Zwillingsbildung bei der thermischen Ermüdung der Mg‐Basislegierung AZ31
Authors: Scholtes B. , Krauß M. 
Published: October 2007

AbstractIn der vorliegenden Arbeit werden Ergebnisse von Untersuchungen zur thermischen Ermüdung der Mg‐Basislegierung AZ31 im Temperaturbereich zwischen ‐50 °C und +290 °C vorgestellt. Die Proben wurden unter Konstanthaltung der totalen Deformation homogen einachsig auf Zug bzw. Druck beansprucht. Das resultierende Materialverhalten wird durch die sich als Funktion der Lastspielzahl ausbildenden Amplituden der Spannung und der plastischen Dehnung sowie durch die Mittelspannung beschrieben. Es ist bekannt, dass AZ31 bei Vorliegen von Textur unter nicht zu hohen Beanspruchungstemperaturen unterschiedliche Spannung‐Dehnung‐Kurven bei Zug‐ oder Druckbeanspruchung zeigt, weil die Bildung von Verformungszwillingen dann von der Beanspruchungsrichtung abhängt. Außerdem kann bei Entlastung und Rückverformung entgegen der ursprünglichen Beanspruchungsrichtung eine Rückbildung von Verformungszwillingen auftreten. Als Folge davon werden auch während der ersten Belastungszyklen bei thermischer Ermüdung charakteristische Auswirkungen dieser Prozesse beobachtet. Die Wechselwirkungen zwischen Verformung, Erholung und Rekristallisation, die in den jeweiligen Temperaturintervallen auftreten und die Mikrostrukturen sowie das Verformungsverhalten bestimmen, werden vorgestellt und ihr Beitrag zum Verlauf der Schädigung wird diskutiert.
Einfluss dehnungsabhängiger Werkstoffeigenschaften auf die Umformbarkeit von Blechwerkstoffen
Authors: Schleich R. , Vlahovic D. , Sindel M. , Liewald M. 
Published: October 2007

AbstractDieser Beitrag zeigt auf Basis experimenteller Untersuchungen Einflüsse dehnungsinduzierter Änderungen von Werkstoffkennwerten auf die Berechnung der Grenzformänderung und die Folgen für sowohl ein‐ als auch mehrstufige Umformprozesse auf. Besonderes Augenmerk liegt dabei auf den Vorteilen dieser differenzierten Betrachtung gegenüber dem in der Praxis üblichen Stand der Technik.
The FEM simulation of mechanical properties characterization of the stent under the quasi‐static loading/unloading. FEM‐ Simulation zur Charakterisierung der mechanischen Eigenschaften von Stents unter quasistatischer Beanspruchung
Authors: Zhi Y.H. , Wang X.M. , Frotscher M. , Eggeler G. , Yue Z.F. 
Published: October 2007

AbstractIn this paper, the detailed stress distributions of NiTi stents have been studied. The primary object of this study is to set up a cell model to reveal the cause of crack initiation for stents. Auricchio’s super‐elastic model is used to analyze the essential stent cell. Two different kinds of models are analyzed. One model is the stent without defect and the other model is a stent with defects caused by laser burrs or TiC inclusions. The structural stress distribution is not only related to a specimen without defect but also to the material of a bulge defect. The maximum stresses of the stent without defect are near the knots, while the one with defects possesses the maximum stress near the surrounding of the bulge defect. It was found that cracks/fractures can easily appear within a distance of 1/3 of the knot to knot spacing. In particular, a stent with TiC inclusion defects is likely to fail near the bulge face defect. Our simulations agree with experimental results.
Experimentelle und numerische Untersuchungen zur Kennzeichnung von Sinterteilen mittels gezielt eingebrachter Fremdpartikel
Authors: Behrens B.‐A. , Gastan E. , Lange F. 
Published: October 2007

AbstractGesinterte Bauteile aus Stahl und Leichtmetalllegierungen finden dank ihrer günstigen Produkteigenschaften zunehmend Anwendung in vielen Industriebereichen. Neben einer hohen Rohstoffausnutzung sowie einer variablen Legierungsbildung bietet die Sintertechnologie die Möglichkeit, Bauteile während des Pressprozesses eindeutig und von außen nicht sichtbar zu kennzeichnen. Als Informationsträger dienen kugelförmige Fremdpartikel, die für erste Versuche in einer quadratischen 4x4 Matrix mit maximal 16 Partikeln im Bauteilinnern platziert werden. Durch die Anzahl und die Anordnung der Partikel wird eine binär kodierte Identifikationsnummer dargestellt. Nach dem Sintern sind die beiden Werkstoffe untrennbar miteinander verbunden. Das Auslesen der gespeicherten Daten erfolgt mit Röntgen‐ oder CT‐Verfahren anhand der unterschiedlichen physikalischen Eigenschaften der Fremdpartikel im Vergleich zum Grundmaterial.
Severe plastic deformation by linear flow splitting
Authors: Müller C. , Bohn T. , Bruder E. , Bruder T. , Landersheim V. , el Dsoki C. , Groche P. , Veleva D. 
Published: October 2007

AbstractDue to the new linear flow splitting forming process the production of bifurcated profiles from sheet metal without lamination of material becomes feasible. The continuous production of such structures takes place incrementally in a modified roll forming machine. By producing those complex parts process‐related changes in the material properties occur as a result of the cold forming. Thus, the assumption of homogeneous properties in the processed part is not valid and a reliable analysis of structural durability is only possible by considering changes in material properties. Investigations on linear flow split profiles show large gradients in the microstructure and properties over the profile cross section. In the areas of low plastification the degree of deformation and the flow stress can be determined by microstructure and hardness measurements. In the severely deformed areas, like the upper flange surface, this determination becomes doubtable. Therefore the electron backscattered diffraction method was used to investigate, if an ultrafine‐grained structure is occurring as it evolves in the processes of severe plastic deformation. Thus, the aim of this paper is the numerical analysis of the linear flow splitting process, the metallographic characterisation of bifurcated profiles and the numerical evaluation of the structural durability with consideration of the gained insights.
Analaysis of failures encountered during rolling of rings of maraging steel
Authors: Nageswara Rao M. , Sivasubramanian K. , Chatterjee M. 
Published: October 2007

AbstractLarge‐sized rings of maraging steel X 2 NiCoMo 18 8 5 (Werkstoff Nr. 1.6359) find application in aerospace. The rings are required to demonstrate high strength and fracture toughness in both radial and axial directions. The processing is accordingly carried out under controlled conditions to realize a microstructure capable of attaining the specified strength and toughness after heat treatment. The rings rolled during initial trials failed to attain the required fracture toughness. Precipitation of carbonitrides at prior austenitic grain (PAG) boundaries in the temperature range 820–980 oC contributed to the failure. Efforts were made to do final rolling through this temperature range, to prevent a microstructure comprising of PAG boundaries decorated by carbonitrides from evolving. To this end relatively low preheating temperatures (1100–1150 oC) were adopted. Failures were encountered in realizing the desired final size and shape of the rings. The mill tripped before the ring rolling could be completed. Failure was analyzed and it was concluded that the problem was due to the high flow stress levels encountered during ring rolling and the relatively low radial loads the mill was capable of delivering.
Friction stir welding of AISI 304 austenitic stainless steel
Authors: Meran C. , Kovan V. , Alptekin A. 
Published: October 2007

AbstractThe objective of this work is to demonstrate the feasibility of friction stir welding (FSW) AISI 304 austenitic stainless steels. The tool used was formed of a tungsten‐based alloy. The specimens were welded on an 11 kW vertical milling machine. Defect‐free welds were produced on 2.5 mm plates of hot‐rolled AISI 304 austenitic stainless steels at travel speeds ranging from 40 to 100 mm/min with a constant rotating speed of 1000 rpm. Tensile strengths and hardness values of the weld interface were determined and microstructure features of these samples were investigated.
Loss of catalase increases malignant mouse keratinocyte cell growth through activation of the stress activated JNK pathway
Authors: Hanke Neale T. , Finch Joanne S. , Bowden G. Timothy 
Published: October 2007

AbstractA cell line that produces mouse squamous cell carcinoma (6M90) was modified to develop a cell line with an introduced Tet‐responsive catalase transgene (MTOC2). We have previously reported that the overexpressed catalase in the MTOC2 cells reverses the malignant phenotype in part by decreasing epidermal growth factor receptor (EGFR) signaling. With this work we expanded the investigation into the differences between these two cell lines. We found that the decreased EGFR pathway activity of the MTOC2 cells is not because of reduced autocrine secretion of an epidermal growth factor (EGF) ligand but rather because of lower basal receptor activity. Phosphorylated levels of the mitogen‐activated protein kinase (MAPK) members JNK and p38 were both higher in the 6M90 cells with low catalase when compared with the MTOC2 cell line. Although treatment with an EGFR inhibitor, AG1478, blocked the increased activity of JNK in the 6M90 cells, a similar effect was not observed for p38. Basal levels of downstream c‐jun transcription were also found to be higher in the 6M90 cells versus MTOC2 cells. Activated p38 was found to down‐regulate the JNK MAPK pathway in the 6M90 cells. However, the 6M90 cells contain constitutively high levels of phosphorylated JNK, generating higher levels of phosphorylated c‐jun and total c‐jun than those in the MTOC2 cells. Inhibition of JNK activity in the 6M90 cells reduced AP‐1 transcription and cell proliferation. The data confirm the inhibitory effects of catalase on tumor cell growth, specifically through a ligand‐independent decrease in the stress activated JNK pathway. © 2007 Wiley‐Liss, Inc.
Analyzing spatial patterns of meteorological drought using standardized precipitation index
Authors: Patel N. R. , Chopra P. , Dadhwal V. K. 
Published: October 2007

AbstractDrought is a slow‐onset, creeping natural hazard and a recurrent phenomenon in the arid and semi‐arid regions of Gujarat (India). In Asia, the standardized precipitation index (SPI) has gained wider acceptance in the detection and the estimation of the intensity, magnitude and spatial extent of droughts. The main advantage of the SPI, in comparison with other indices, is that the SPI enables both determination of drought conditions at different time scales and monitoring of different drought types. This index captures the accumulated deficit (SPI < 0) or surplus (SPI > 0) of precipitation over a specified period, and provides a normalized measure (i.e. spatially invariant Z score) of relative precipitation anomalies at multiple time scales. In the present study, monthly time series of rainfall data (1981–2003) from 160 stations were used to derive SPI, particularly at 3‐month time scales. This 3‐month SPI was interpolated to depict spatial patterns of meteorological drought and its severity during typical drought and wet years. Correlation analysis was also done to evaluate usefulness of SPI to quantify effects of drought on food grain productivity. Further, time series of SPI were exploited to assess the drought risk in Gujarat. Copyright © 2007 Royal Meteorological Society
Wakeby distribution for representing annual extreme and partial duration rainfall series
Authors: Öztekin Tekin 
Published: October 2007

AbstractIn this study, to measure the upper right tail estimate performances for representing annual extreme and partial duration precipitation series at 31 stations in the northeastern and southeastern United States, the results of five‐parameter Wakeby‐L moments distribution were compared to those by beta‐κ, and beta‐P distributions. The statistics of modified Anderson‐Darling and average deviation (AD) and the bootstrap resampling to extrapolate the right tail beyond the data showed that the Wakeby distribution gave mostly better results than beta‐κ and beta‐P, and sometimes it produced comparable results to those by beta‐κ and beta‐P. Copyright © 2007 Royal Meteorological Society
Presence of immunoreactive gonadotropin releasing hormone (GnRH) and its receptor (GnRHR) in rat ovary during pregnancy
Authors: Sengupta Anamika , Chakrabarti Nilkanta , Sridaran Rajagopala 
Published: October 2007

AbstractThe present study aims at quantification of gonadotropin releasing hormone (GnRH) by radioimmunoassay, relative expression of its mRNA by real‐time PCR accompanied by its cellular localization in the rat ovary by immunonohistochemistry (IHC) during different time points of pregnancy. To determine the involvement of endogenous ovarian GnRH in receptor mediated local autocrine/paracrine functions within the ovary, the cell specific localization of the classical receptor for GnRH (GnRHR) in the ovary by IHC and expression pattern of its mRNA were studied during pregnancy. Receptor expression during each time point within the ovary was reconfirmed by Western blot analysis accompanied by densitometric analysis of the signal intensity. Results reveal that the content of ovarian GnRH reaches its maximum on Day 20. The densitometric analysis of GnRHR receptor expression from Western blot study exhibits a decreasing trend by Day 20. Presence of GnRH and GnRHR mRNA in the ovary indicates the local synthesis of both ligand and receptor in the rat ovary. Differential expression of GnRH/GnRHR in the corpus luteum throughout pregnancy strengthens the hypothesis of the involvement of ovarian GnRH in local ovarian functions by receptor‐mediated mechanisms. The expression of GnRH and GnRHR in the atretic antral follicles is indicative of the possible involvement of this decapeptide in processes like follicular atresia. The expression of GnRH/GnRHR in the nonatretic antral follicles and their oocytes requires further in‐depth investigation. Collectively, this study for the first time reveals the presence of endogenous ovarian GnRH/GnRHR supporting their possible involvement in local autocrine/paracrine functions during pregnancy. Mol. Reprod. Dev. 75: 1031–1044, 2007. © 2007 Wiley‐Liss, Inc.
Strain and stress computations in stochastic finite element methods
Authors: Ghosh Debraj , Farhat Charbel 
Published: October 2007

AbstractThis paper focuses on the computation of statistical moments of strains and stresses in a random system model where uncertainty is modeled by a stochastic finite element method based on the polynomial chaos expansion. It identifies the cases where this objective can be achieved by analytical means using the orthogonality property of the chaos polynomials and those where it requires a numerical integration technique. To this effect, the applicability and efficiency of several numerical integration schemes are considered. These include the Gauss–Hermite quadrature with the direct tensor product—also known as the Kronecker product—Smolyak's approximation of such a tensor product, Monte Carlo sampling, and the Latin Hypercube sampling method. An algorithm for reducing the dimensionality of integration under a direct tensor product is also explored for optimizing the computational cost and complexity. The convergence rate and algorithmic complexity of all of these methods are discussed and illustrated with the non‐deterministic linear stress analysis of a plate. Copyright © 2007 John Wiley & Sons, Ltd.
An explicit discontinuous Galerkin method for non‐linear solid dynamics: Formulation, parallel implementation and scalability properties
Authors: Noels L. , Radovitzky R. 
Published: October 2007

AbstractAn explicit‐dynamics spatially discontinuous Galerkin (DG) formulation for non‐linear solid dynamics is proposed and implemented for parallel computation. DG methods have particular appeal in problems involving complex material response, e.g. non‐local behavior and failure, as, even in the presence of discontinuities, they provide a rigorous means of ensuring both consistency and stability. In the proposed method, these are guaranteed: the former by the use of average numerical fluxes and the latter by
the introduction of appropriate quadratic terms in the weak formulation. The semi‐discrete system of ordinary differential equations is integrated in time using a conventional second‐order central‐difference explicit scheme. A stability criterion for the time integration algorithm, accounting for the influence of the DG discretization stability, is derived for the equivalent linearized system. This approach naturally lends itself to efficient parallel implementation. The resulting DG computational framework is implemented in three dimensions via specialized interface elements. The versatility, robustness and scalability of the overall computational approach are all demonstrated in problems involving stress‐wave propagation and large plastic deformations. Copyright © 2007 John Wiley & Sons, Ltd.
Polymeric photoacid generators for direct photochemical modification of surface
Authors: Jung Sung‐Ouk , Jung Myung‐Sup , Choi Tae‐Lim , Huh Nam , Ko Christopher , Jung Hee‐Tae 
Published: October 2007

AbstractTo achieve easy spin coating and enhanced efficiency in the photolithographic process for the direct photochemical modification of surface, we incorporated photoacid generator (PAG) into polymer backbone. Bis‐(4‐hydroxy‐phenyl)‐(4‐methoxy‐3,5‐dimethyl‐phenyl)‐sulfonium chloride was synthesized as a monomer, and was polymerized with sebacoyl chloride and terephthaloyl chloride. The resulting polymeric PAG in chloride salt form was converted to the p‐toluenesulfonate and 1‐naphthol‐5‐sulfonate forms with ion‐exchange reactions. By the photolithographic process with the polymeric PAG, the protecting groups of the linker molecules self‐assembled onto a glass plate were micropatterned to produce an amine pattern for the microarray of oligonucleotides. The acids generated from the polymeric PAG effectively deprotect the acid‐labile protecting groups of the linker molecules through a chemical amplification process in the exposed region. After the treatment of the patterned amino groups with a fluorescent dye, the pattern profiles were observed with a fluorescence scanner. The fluorescence image reveals a well‐defined pattern at a micro level, which clearly indicates that the polymeric PAGs have a great potential in photochemical surface modification for the microarray of oligonucleotides. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of polymerization methods on the residual monomer level of acrylic resin denture base polymers
Authors: Çelebi Nilüfer , Yüzügüllü Bulem , Canay Şenay , Yücel Ülkü 
Published: October 2007

AbstractWearing dental acrylic prosthesis causes adverse reactions to oral tissues due to bioactive leachables from resins such as residual methyl methacrylate (MMA). The aim of this study is to apply the high performance liquid chromatography (HPLC) method to quantify and compare the amount of MMA monomers released from denture base resin polymers processed by the conventional compression molding method (Paladent), microwave polymerization (Acron MC), and injection molding technique (PalaXpress). Six specimens of 10 ± 0.2 mm in diameter and 2.0 ± 0.2 mm in thickness of each material were prepared according to manufacturer's instructions. Specimens were stored in nanopure water at room temperature (23 ± 2°C) for 4 hr, 48 hr, 8 days, and 15 days separately. Residual MMA released into water was determined with HPLC for all time intervals. Data for all time intervals were analyzed among each group using the Friedman test and differences were found to be statistically significant for all time intervals for Acron MC, Paladent, and PalaXpress (p > 0.05). Kruskal–Wallis test was used to compare changes of residual MMA within time intervals among denture base resin groups and statistically significant differences were found between all time intervals (p > 0.05). Acron MC exhibited significantly lower residual MMA leach compared both to Paladent and PalaXpress, and Paladent showed more residual MMA leach compared to PalaXpress. Residual MMA leach for Acron MC, PalaXpress, and Paladent showed statistically significant leach in the first 48 hr of immersion in water followed by gradual longer‐lasting moderate increase until the 15 day interval which was not statistically significant (p < 0.05). Copyright © 2007 John Wiley & Sons, Ltd.