bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abscheidung von Hartstoffschichten des Typs (B,C,N) bei niedrigen Beschichtungstemperaturen im PACVD‐Prozeß
Authors: Rie K.‐T. , Gebauer A. , Wöhle J. , Erker G. , Mohr R. , Sarter C. 
Published: December 2004

AbstractIn dieser Studie wurde die Abscheidung von (B,C,N)‐Schichten unter Verwendung der auf einem, neuen Syntheseweg dargestellten metallorganischen Verbindung C8H18BN im DC‐Puls‐PACVD‐Prozeß bei niedrigen Beschichtungstermperaturen (250°C) unter‐sucht. Es konnte gezeigt werden, daß doe Herstellung von (B,C,N)‐Schichten mit guter Härte und Haftfestigkeit im betrachteten Parameterraum möglich ist.
Umwandlungsverhalten und Härtbarkeit von Gußeisen mit Lamellengraphit. Teil III: Charakterisierung des Umwandlungsverhaltens
Authors: Schreyer G. W. 
Published: December 2004

AbstractIn den Teilen I und II des Beitrages wurden die theoretischen Grundlagen der Härtbarkeit von Gußeisen mit Lamellengraphit und die darauf aufbauenden Härtbarkeitsuntersuchungen an repräsentativen Gußeisenwerkstoffen erörtert.Im III. Teil dieses Berichtes wird das Umwandlungsverhalten von Gußeisen mit Lamellengraphit charakterisiert und Möglichkeiten seiner graphischen Darstellung an Hand von kontinuierlichen Stirnabschreckproben‐Diagrammen (KSA) diskutiert.
Schwingfestigkeitsbeurteilung randschichtverfestigter Proben auf der Grundlage örtlicher elastisch‐plastischer Beanspruchungen
Authors: Bruder T. , Seeger T. 
Published: December 2004

AbstractEs werden Modelle für eine ingenieurmäßige Lebensdauerberechnung randschichtverfestigter Bauteile beschrieben. Totaldehnungskontrollierte Einstufenversuche an unbehandelten Proben, Härte und Eigenspannungsmessungen sowie in bestimmten Fällen auch FE‐Analysen dienen zur Bestimmung der Eingabedaten für die Rechenmodelle. Für zwei verschiedene Kombinationen von Randschichtverfestigungsverfahren und Grundwerkstoff wurden Schwingfestigkeitsversuche an ungekerbten und gekerbten axial belasteten Proben durchgeführt. Berechnungs‐ und Versuchsergebnisse werden gegenübergestellt.
Herstellung diamanthaltiger, enkonturnaher Metallmatrix‐Verbundwerkstoffe durch Laserstrahlbeschichten
Authors: Lang A. , Bergmann H. W. 
Published: December 2004

AbstractDie vorliegende Arbeit berichtet über die kontinuierliche, endkonturnahe Herstellung von Metall‐Matrix‐Compositeschichten. Hier zu werden Pulvergemische in einem einstufigen Prozeß durch Laserstrahlbeschichten in einer Kokille auf ein Substrat aufgebracht. Bei dem Verfahren gelingt es, thermisch instabile Harstoffe, wie z. B. Diamanten, zunächst gleichmäßig in einer schmelzflüssigen Matrix zu verteilen und nach anschileßender Erstarrung eine gute Bindung zwischen Metallmatrix und Hartstoff zu erreichen. Eine thermische Schädigung der Diamanten ist weder durch rönt‐genographische noch durch mechanische Tests nachzuweisen. Durch Anpassung von Pulverförderrate, Vorschubgeschwindigkeit und mittlerer Laserleistung lassen sich mehrere Millimeter hohe, technisch verwendbare Schneidbeläge (z. B. Honleistenbeläge) mit einstellbarem Aufmischungsgrad zwischen Metallmatrix und Substrat erzeugen. Der „overspray”︁ des Prozesses liegt deutlich unter 10%. Durch die Ausbildung der Kokille (Kühlwirkung) kann man die Korngröße der Matallmatrix beeinflussen. Bei vergleichbarer Diamantkonzentration weisen laserstrahlbeschichtete Honleisten vergleichbare Schneidleistungen auf wie konventionell gesinterte bei ähnlichen Werkzeugstandzeiten und Rauheiten des geschonten Werkstücks. Die Beschichtungsgeschwindigkeiten lie gen bei Verwendung eines gepulsten l kW Nd:YAG‐Lasers beica. 2 cm3/min. Stichversuche haben gezeigt, daß sich die beschriebene Technik auch auf andere Schichtsysteme übertragen läßt.
Auswirkungen der Schädigungsanisotropie auf die Lebensdauer von Stählen bei Zeitstandbeanspruchung
Authors: El‐Magd E. , Betten J. , Palmen P. 
Published: December 2004

AbstractZiel der Untersuchung ist die Bestimmung des Einflusses von Kriechschädigung und Belastungsvorgeschichte auf das weitere Kriechverhalten nach einer Änderung der Belastungsrichtung. Die Änderung der Beanspruchungsrichtung hat einen starken Einfluß auf die Kriechbruchzeiten. Es wird ein Modell vorgestellt, mit dem dieser Einfluß beschrieben werden kann.
Influence of Topical Fluorides on corrosion behaviour of silver amalgam alloys
Authors: Khamis E. , Seddik M. 
Published: December 2004

AbstractPotentiodynamic polarization and cyclic voltametry measurements were employed to study the effect of topical fluoride preparations on corrosion of silver amalgam alloy in synthetic saliva and aqueous fluoride solutions. Results support that small amounts of copper and indium alloyed to silver – tin amalgam enhance corrosion resistance considerably. Indiloy shifts both the open circuit potential and the anodic polarization curve to more positive potential values, this lead to a decreases in the current density. The weak activity of Indiloy as compared with Spheraloy is attributed to the fact that the amount of γ2 phase (tin–mercury) present in the former is much lesser than that present in the latter. Findings also show that fluoride solutions (NaF, SnF and SnF + HCI) enhance the dissolution rate of the investigasted alloys and the polarization curves illustrate the appearance of an active – passive transitions. This behaviour was discussed on the basis of complex formation. Cyclic voltammograms confirm the results obtained from the potentiodynamic polarization measurements and elucidate the anodic oxidation peaks of silver oxide and copper verifying the proposed mechanism.
Einfluß der Wärmeermüdung im Tieftemperaturbereich (77 K ⇔︁ 373 K) auf mechanische Eigenschaften der (α + β)‐Ti‐Legierung
Authors: Ziaja Jerzy 
Published: December 2004

AbstractUntersucht wurde der Einfluß der Wärmeermüdung im Tieftemperaturbereich (77 K ⇔︁ 373 K) (WETT) auf einige mechanische Eigenschaften wie auch auf die Kristallgitter‐Parameter der α und β‐Phasen der (WT3‐1)‐Titan‐Legierung bei Temperaturen von 295 K und 77 K.Die Ermüdungsuntersuchungen waren beim Biegen unter einem zweiachsigen Spannungszustand durchgeführt worden. Es wurde festgestellt, daß die Wirkung der WETT auf die Eigenschaften von der Anzahl der WETT‐Zyklen abhängig ist: Während nach 100 Zyklen eine wesentliche Verbesserung der Eigenschaften festzustellen war, wurde dagegen nach 500 Zyklen eine eindeutige Verschlechterung der Eigenschaften ermittelt.Die mikroskopischen und röntgenographischen Untersuchungen haben es ermöglicht, den Einfluß der Zwillingsbildung auf die WETT‐ und den Ermüdungsverlauf zu bestätigen: der Verlauf der Verformungsprozesse ist von den Eigenspannungen, die während der WETT entstehen und als Stimulus‐Faktoren anzusehen sind, beeinflußt worden.
Mikrostrukturelle Erscheinungen in der Randschicht einsatzgehärteter Bauteile
Authors: Lerche W. , Lohrmann M. , Edenhofer B. , Gräfen W. , Bouwman J. W. 
Published: December 2004

AbstractEine mehr oder minder ausgeprägte negative Beeinflussung des Randbereiches von Bauteilen während des Einsatzhärtens, durch die Aufnahme von Nicht‐Metall‐Elementen aus der Atmosphäre, ist seit langem bekannt. Diese am häufigsten durch Sauerstoff hervorgerufene Erscheinung ist die Randoxidation, welche insbesondere eine Verminderung der gelösten härtbarkeitsbeeinflussenden Legierungselemente Mangan, Chrom und Silizium durch Oxidbildung bewirkt. Die vorliegende Arbeit stellt mikroskopische und spektroskopische Möglichkeiten zur Kennzeichnung der Erscheinungsformen der Randoxidation sowie kritische Überlegungen zu deren Bewertung dar. Zusätzlich wird auf eine weniger bekannte mögliche negative Beeinflussung des Randbereiches durch die Abwanderung von härtbarkeitsbestimmenden Legierungselementen hingewiesen, welche insbesondere bei Einsatzhärtungen im Unterdruck bzw. mit Plasmaunterstützung auftreten kann.
Efficacy of antibodies against a chimeric synthetic peptide encompassing epitopes of bonnet monkey (Macaca radiata) zona pellucida‐1 and zona pellucida‐3 glycoproteins to inhibit in vitro human sperm‐egg binding
Authors: Sivapurapu Neela , Hasegawa Akiko , Gahlay Gagandeep K. , Koyama Koji , Gupta Satish K. 
Published: December 2004

AbstractImmunocontraception achieved by immunization with zona pellucida (ZP) glycoproteins is invariably associated with ovarian dysfunction. Use of ZP glycoprotein‐based synthetic peptides as immunogens has been proposed to overcome adverse side effects on ovaries. In the present study, a chimeric peptide encompassing the epitopes of bonnet monkey (Macaca radiata) ZP glycoprotein‐1 (bmZP1; amino acid residues 251–273) and ZP glycoprotein‐3 (bmZP3; amino acid residues 324–347), separated by a tri‐glycine spacer, was synthesized and conjugated to diphtheria toxoid (DT). Immunization of female BALB/cJ mice and bonnet monkeys with the chimeric peptide led to generation of antibodies that reacted with the chimeric peptide, individual bmZP1 & bmZP3 peptides, and also recombinant bmZP1 and bmZP3 proteins expressed by E. coli in an ELISA. Indirect immunofluorescence studies revealed that the immune serum also recognized human as well as bonnet monkey ZP. A significant inhibition of human sperm binding to ZP was observed with antibodies generated against the chimeric peptide in mice (P = 0.0001) as well as monkeys (P = 0.0002) in a hemizona assay (HZA). The inhibition efficacy was significantly higher than that observed by using antibodies against the individual bmZP1 and bmZP3 peptides. Interestingly, no ovarian pathology was observed in female bonnet monkeys immunized with the chimeric peptide. These studies have demonstrated that the chimeric peptide encompassing peptides of multiple ZP glycoproteins may be a promising candidate antigen for designing immunocontraceptive vaccines. Mol. Reprod. Dev. 70: 247–254, 2005. © 2005 Wiley‐Liss, Inc.
Nurses, smoking, and the workplace
Authors: Sarna Linda , Bialous Stella Aguinaga , Wewers Mary Ellen , Froelicher Erika Sivarajan , Danao Leda 
Published: December 2004

AbstractThe purpose of this study was to examine attitudes and experiences of nurses regarding smoking and smoking cessation in the workplace. Eight focus groups were conducted with current or former smokers (n = 60). A questionnaire provided information about smoking history. Content analysis revealed six themes: taking breaks, stress and smoking, social support from colleagues, hiding smoking from patients and their families, impact of workplace smoking restrictions, and challenges to smoking cessation in the workplace. Nurses who smoke were perceived as taking more breaks and spending less time with patients than those who do not smoke. These findings document the impact of smoking among nurses in the workplace. Strategies are needed to support smoking cessation efforts of nurses as an important occupational health issue. © 2004 Wiley Periodicals, Inc. Res Nurs Health 28:79–90, 2005
Computations of Eigenvalue Avoidance in Planar Domains
Authors: Betcke T. , Trefethen L. N. 
Published: December 2004

AbstractThe phenomenon of eigenvalue avoidance is of growing interest in applications ranging from quantum mechanics to the theory of the Riemann zeta function. Until now the computation of eigenvalues of the Laplace operator in planar domains has been a difficult problem, making it hard to compute eigenvalue avoidance. Based on a new method this paper presents the computation of eigenvalue avoidance for such problems to almost machine precision. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient numerical solution of the LQR‐problem for the heat equation
Authors: Saak Jens , Benner Peter 
Published: December 2004

AbstractWe discuss how the theory developed by Banks and Kunisch can be applied to a modified version of a controlled heat transfer model introduced by Tröltzsch and Unger. In the numerical implementation we use ALBERT(A) to establish the required FEM–semidiscretisation in space. The resulting algebraic Riccati equation (ARE) is of large dimension (n > 1000). It is shown how the LyaPack software package can be used to compute the optimal feedback without solving the ARE directly. In the closing section we present numerical results comparing different implementational approaches and cost functions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modeling of the equilibrium shapes of a ferrofluid drop in an external magnetic field
Authors: Lavrova O. , Matthies G. , Polevikov V. , Tobiska L. 
Published: December 2004

AbstractA numerical solution strategy for calculating equilibrium free surfaces of a magnetic fluid under the action of a magnetic field is proposed and applied to determine shapes of a linear magnetisable ferrofluid drop in a uniform magnetic field. Hysteresis phenomena for the drop deformation and the drop shapes with ends, close to conical, were observed numerically. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Taylor method in the field of Mikusiński operators
Authors: Takači Djurdjica 
Published: December 2004

AbstractThe approximate solution of a class of differential equations, in the field of Mikusiński operators is constructed by using the Taylor method. The obtained results are applied to a class of partial integro–differential equations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flow of short‐glass‐fiber‐filled thermoplastics in channels of circular of thin rectangular cross‐section
Authors: Chan W. W. , Charrier J. , Vadnais P. 
Published: December 2004

AbstractA pressure‐flow‐type modular rheonmeter was developed specifically for the stuidy of the flow of unfilled thermoplastic melts and for the same melts with particles of relatively large dimensions in channels of shapes and dimensions encompassing those encountered in the injections molding of commercial parts. Experimental results are reported here for the case of polypropylene with 20 and 40 percent by weight of short glass fibers. The handling of the wide range of data, suing the concept of an end correctuion(Bagley plot), led to a reasonably unique viscosity vs. Shear‐rate relationship for each material and confirmed that fibers have little effect on such a relationship for the range of shear rates involved in commercial processing. End effects were examined systematically for the wide range of shear rates and geometries, and the data, although difficult to correlate at present, should prove useful to rheologists trying to elucidate the flow in such areas.
Mechanical behavior of reinforced polyurethane foams
Authors: Siegmann A. , Kenig S. , Alperstein D. , Narkis M. 
Published: December 2004

AbstractThe mechanical behavior of three‐phase reinforced polyurethane (PU) foam composites was investigated. Chopped‐glass fibers, glass beads, and graphite powder were used as reinforcing materials. Emperimental results indicated that chopped‐glass fibers enhance the foam mechanical properties in tension, while glass beads and graphite powder tend to improve the mechanical properties in compression. Microscopical observations revealed that the reinforcing filler location is within the cell walls acting as a matrix reinforcement. A modified Kerner equation, based on a model that assumes the superposition of a porous matrix and a rigid particulate filler, was compared with measured elastic moduli of the three‐phase composite foams.
Acoustic cavitation and its effect on flow in polymers and filled systems
Authors: Peshkovskii S. L. , Friedman M. L. , Tukachinskii A. I. , Vinogradov G. V. , Enikolopian N. S. 
Published: December 2004

AbstractWe have studied the phenomenon of acoustic cavitation under the action of volume ultrasonic oscillations on polymer melts and filled compositions. This phenomenon and the stress state of the material have been studied by means of a device for the visualization of flow in polarized light. It has been shown that the process of cavity formation in high‐viscosity systems has a certain threshold and that the critical amplitude of oscillations depends on the duration of ultrasonics action. The effect of acoustic field on the melts of commercial polymers and filled compositions results in structural changes. In addition, a sharp increase of the melt flow is observed. Model experiments have shown that the size of particles and filler distribution can also be changed by utrasonic oscillation.
Mechanical characterization of sheet molding compound composites
Authors: Chaturvedi S. K. , Sun C. T. , Sierakowski R. L. 
Published: December 2004

AbstractThe present work was aimed at providing basic mechanical property characterization of five different sheet molding compound (SMC) materials with glass content varying from 30 to 65 percent by weight. In particular, the objectives were to find variation in their tensile, flexural, and shear properties along with some information on fabrication‐induced anisotropy that may be present in these materials. The flexural properties were measured using three‐point bend tests, and double‐rail shear tests were conducted for in‐plane shear properties. A significant scatter was observed in all the properties, and no conclusive evidence about the fabrication‐induced anisotropy was found, Flexural strength of each material was found to be significantly greater than the tensile strength. Finally, some interesting features associated with their tensile and flexural failure modes have also been discussed.
Variability in static strengths of sheet molding compounds (SMC)
Authors: Shirrell C. David 
Published: December 2004

AbstractIn this paper, the variability in static strengths of six glass fiber‐reinforced sheet molding compounds (SMC) is reported. This variability was shown not to be caused by macroscopic variations in fiber, resin, filler, or void content nor gross fiber anisotropy. Weibull statistics were used to accurately characterize this variability, Random flaw models with the flaws being distributed in the volume, surface, or edge were shown not to predict the observed static strength variability in SMC.
High strength continuous glass strand—polyurethane composites by the reaction injection molding process
Authors: Dominguez Richard J. G. , Rice D. Marvin 
Published: December 2004

AbstractConsiderable work has been published on the subject of filling reaction injection molded (RIM) polyurethane elastomers with discontinuous particulate fillers such as milled glass fibers, flake glass and wollastonite, RIM polyurethane elastomers are filled for three reasons: (1) to increase stiffness, (2) to decrease the linear coefficient of thermal expansion, and (3) to improve thermal dimensional stability. Discontinuous particulate fillers either do not appreciably change strength properties, e.g., tensile strength or they cause dramatic reduction in strength properties, e.g., impact resistance. To overcome these deficiencies, new fillers are necessary. Once such material is continuous glass strand mat. In order to make continuous glass strand‐polyurethane composites by the RIM process, a particular balance of ingredients to produce the RIM polyurethane must be used. We will discuss the properties of these composites and suggest possible applications and future directions in which this research might proceed.
Properties of mat reinforced reaction injection molded materials
Authors: Gonzalez V. M. , Macosko C. W. 
Published: December 2004

AbstractReinforced reaction injection molding, RRIM, using preplaced glass‐fiber mats is an attractive method for production of composite materials. The effect of the glass‐fiber mat on the properties of a styrene‐dimethacrylate copolymer (SDM) is analyzed. Thermal conductivity as a function of porosity was measured. A simple method to obtain the thermal coefficient of linear expansion using the Rheometrics System Four is presented. Dynamic mechanical properties were measured using torsion and three‐point bending of rectangular bars. Adding the glass‐fiber mat increased the storage modulus (G′) by a factor of 5 below Tg and 100 above it. Empirical correlations for the composite modulus as a function of glass‐fiber content below and above Tg are presented. The increase in glass‐transition temperature with increasing glass‐fiber content is discussed.
Dynamic and steady state flow of polypropylene/mica systems
Authors: Utracki L. A. , Favis B. D. , Fisa B. 
Published: December 2004

AbstractSix compositions containing commercial polypropylene, PP, and monodispersed, untreated phlogopite mica were prepared. Their rheological properties were determined at 180°C in dynamic and capillary flows. The results are discussed in terms of strain‐induced orientation of mica flakes. Two critical volume fractions were found to affect the flow: ψc defined as a concentration of flakes overlap and ψm as a concentration of maximum packing of freely sedimenting particles. At ψ > ψc yield stress and at ψ > ψm non‐linearity in dynamic response were observed.
Factors affecting the surface texture in extruded mica‐polypropylene composites
Authors: Favis B. D. , Fisa B. , Sanschagrin B. 
Published: December 2004

AbstractA Taylor‐Hobson Talysurf instrument was used to quantify the surface roughness of phlogopite mica‐polypropylene extrudates. The rate of feeding and the speed of rotation of the screw were found to have a significant effect on the surface texture. Under the appropriate conditions of extrusion the roughness of 40 percent (by weight) mica‐filled polypropylene extrudates could be reduced by a factor of three. This effect was found to be independent of the extrusion rate.
Fiber composites with internal stresses under control
Authors: Piggott M. R. , Woo M. S. 
Published: December 2004

AbstractRecently it has become possible to control the internal stresses in fiber composites by the use of special expanding monomers. Carbon fiber‐reinforced epoxy pultrusions have been made in which the epoxy was copolymerized with spiro ortho carbonates. The resulting composites had as little as one third of the usual internal stresses and were tougher than the equivalent carbon‐epoxies made without the spiro. Their tensile strengths and shear strengths suffered no reduction, and there was a slight increase in compression strength in some cases. Water resistance of the composites was increased slightly, and durability in fatigue was much increased by the use of the spiro, probably due to improved adhesion between the fibers and the matrix. Theoretical considerations indicate that the internal shrinkage stress must be controlled at a low value, and not eliminated entirely, for best effects. These controlled shrinkage composites bear the trade name COMACO composites in Canada.
Design and construction of a reinforced plastic oar for use in competitive and recreational rowing
Authors: Prinsen John H. , Wilkins Graham 
Published: December 2004

AbstractIn 1982 Paluski Boats with the assistance of the National Research Council of Canada, embarked on a project to design a reinforced plastic oar. The problems to be solved involved not only the construction of a shaft of sufficient strength, but also the development of a light and durable F.R.P. blade, as well as fixing to the pole a suitable strong and adjustable pivot point. The shaft was manufactured, borrowing techniques developed for ski poles and windsurfing masts, in the form of a tapered epoxy and carbon‐fiber pole. The blade was formed with an outer shell of epoxy and fiberglass laminate which was then filled with a two‐part structural foam. The pivot point, or ‘collar/sleeve assembly’ was made by molding around the shaft a solid section of polyurethane. The new plastic oars are lighter, less‐expensive, need no regular maintenance and are practically impossible to break.