The stability behaviour of hard material coatings on alloyed steel substrates

The stability behaviour of hard material coatings made by CVD on different alloyed and carbon steel substrates depends on the properties of both substrate and coating. SEM in-situ investigations on the tension loaded surface of bended samples may be used to observe crack nucleation and growth in brittle hard material coatings such as TiC, TiCN on low alloyed and carbon steels. From the crack distance distributions some important parameters of mechanical stability such as the threshold value of fracture σ_th, the Weibull-parameter β and the ratio of the strength distribution function F and a characteristic length D may be estimated. The threshold value for fracture in the coatings σ_th decreases with increasing coating thickness for all steel-coating combinations. The threshold value also decreases if a heat treatment is made on the steel-coating system. This is due to the relaxation of the internal stress in the coating. The mean strength of the TiC-coatings decreases and the strength variance (measured by the Weibull-parameter β) increases with increasing coating thickness and therefore the mechanical stability of coatings decreases with growing thickness. The ratio of the strength distribution function F and the characteristic distance between defects D as a measure of crack density depends on the deformation behaviour of the steel as well as on the strength and the defect structure of the coating.     

Item and order information in subject-performed tasks and experimenter-performed tasks.

This study investigated the enactment effect from the perspective of the item-order hypothesis (e.g., M. Serra & J. S. Naime, 1993). The authors assumed that in subject-performed tasks (SPTs), item encoding is improved but order encoding is disrupted compared with experimenter-performed tasks (EPTs), that order encoding of EPTs is only better in pure lists, and that the item-order hypothesis is confined to short lists. Item information was tested in recognition memory tests, order information in order reconstruction tasks, and both item and order information in free-recall tests. The results of 5 experiments using short (8 items) and long lists (24 items) in a design with list type (pure, mixed) and encoding condition (EPT, SPT) as factors supported the hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of High-Velocity Suspension Flame Sprayed (HVSFS) glass coatings

High-Velocity Suspension Flame Spraying (HVSFS) has recently emerged as a potential alternative to conventional HVOF-spraying: employing liquid suspensions instead of dry powder feedstock enables the use of very fine grain-sized particles, resulting in small-sized lamellae. Thin, low-porosity coatings can thus be manufactured. This paper details the first attempt at manufacturing glass coatings using the HVSFS technique: these coatings can have multiple applications (anti-corrosion coatings on metal and ceramic substrates, bio-compatible coatings, etc). A CaO–ZrO₂–SiO₂ glass frit was selected for this attempt. Excellent potentialities emerged (very low porosity), but some problems still existed (big “droplet-like” features on the coating surface), which have recently been largely overcome thanks to process modifications.     

Entwicklung einer SOA-basierten Webanwendung zur Buchung und Verwaltung von Segeltouren: Proprietäre Software vs. Open Source

Ohne Zusammenfassung Zuschriften zum Studierendenforum bitte an: Universit?t Bayreuth, Lehrstuhl BWL VII (Wirtschaftsinformatik), Prof. Dr. Torsten Eymann, Redaktion Studierendenforum, z. Hd. Dipl.-Wirtschaftsinformatiker Stefan K?nig, Universit?tsstra?e 30, 95447 Bayreuth, stefan.koenig@uni-bayreuth.de     

Refined Epistemic Entrenchment

Epistemic entrenchment, as presented by Gärdenfors and Makinson (1988) and Gärdenfors (1988), is a formalisation of the intuition that, when forced to choose between two beliefs, an agent will giveup the less entrenched one. While their formalisation satisfactorilycaptures the intuitive notion of the entrenchment of beliefs in a number ofaspects, the requirement that all wffs be comparable has drawn criticismfrom various quarters. We define a set of refined versions of theirentrenchment orderings that are not subject to the same criticism, andinvestigate the relationship between the refined entrenched orderings,the entrenchment orderings of Gärdenfors and Makinson, and AGM theorycontraction (Alchourrón et al., 1985). To conclude, we compare refinedentrenchment with two related approaches to epistemic entrenchment.     

Analysis of supercritical carbon dioxide extracts from cones and leaves of a Humulus lupulus L cultivar

Extracts obtained by supercritical carbon dioxide extraction of cones and leaves of hop (Humulus lupulus L) at different combinations of temperature and pressure were analysed for their α- and β-acids and volatiles, using HPLC and GC respectively. The yield and composition of the mixtures of bitter compounds from the cones were largely influenced by the temperature and pressure applied during the extraction. Bitter compounds could not be detected in the extracts from the leaves. The most important volatile components identified were β-myrcene, β-caryophyllene and α-humulene. The extraction parameters also influenced the composition of the mixture of volatiles from the cones and leaves, 40°C and 20.0 MPa being optimum for the extraction of both bitter compounds and volatiles, which are thought to be important for the aroma of beer.     

Fundamental Uncertainty Rotationally Symmetric and Anamorphic Laser Triangulation

Rotationally symmetric triangulation （RST） sensor is one of the newest developments in laser distance measurement. Speckle is also the fundamental uncertainty factor in this kind of sensors. A detailed analysis of centroid uncertainty in RST is presented in this paper. The analytic expression of centroid uncertainty limit when measuring an optical rough surface is derived. It is shown that the uncertainty limit in RST, and also in anamorphic triangulation, is dependent on the solid angle subtended by entrance pupil as seen from the illuminated laser spot, as well as the laser wavelength. Results of simulation and experiments verify the deriving. The uncertainty limit in RST is about 1/5 of the one in traditional triangulation with same numerical aperture and triangulation angel. It＇s also analysed how the aberration of the optical system influence the uncertainty limit.     

Räumlich hochauflösende Flammendiagnostik in Flammen mit kohlenstoffhaltigen Brennstoffen mit Hilfe der spontanen Ramanspektroskopie

Zusammenfassung Mit Hilfe der spontanen Ramanspektroskopie wurden umfangreiche, berührungslose, r?umlich hochaufgel?ste, station?re Messungen der Temperatur-und Stoffverteilungen in laminaren und turbulenten Flammen mit kohlenstoffhaltigen Brennstoffen durchgeführt Im in solchen Flammen mit st?rkerleuchtendem Untergrund messen zu k?nnen, wurde eine Ramanme?apparatur bestehend aus einem mit akustooptischem Auskoppler gepulsten Argon-Ionenlaser und schmalbandigen Interferenzfiltern eingesetzt. Eine zus?tzliche Erh?hung der Laserleistung am Me?ort wurde durch ein Multipass-Laserfokussierung erreicht. Diese Ma?nahmen bewirkten eine Erh?hung des Me?signal/Untergrund-Verh?ltnisses um mehr als den Faktor 150 gegenüber konventionellen Ramanme?apparaturen, die mit kontinuierlich betriebenen Argon-Ionenlasern arbeiten. Die Arbeit wurde in dankenswerter Weise von der Deutschen Forschungsgemeinschaft finanziell gef?rdert