Separate assessment of porosity and uncombined carbon in cemented carbides

Porosity and uncombined carbon in cemented carbides are traditionally assessed by comparison to standardized microstructure charts, such as those in ISO 4505-1978. To improve the accuracy in the characterization a fully automatic image analysis procedure has been developed. The analysis is performed using light optical microscopy on unetched polished specimens. The implemented algorithm separates uncombined carbon, C-defects, from pores, A- and B-defects. Pores are approximately distributed in a random way in the structure. Uncombined carbon is on the other hand precipitated into clusters of carbon particles. This difference is together with defect size used as a base for the separation. Small defects situated close together are classified as C-defects, small isolated defects as A-pores and large defects as B-pores. Pores are found to be more round than the somewhat elongated C-defects. The difference in shape is significant and can also be used as a separation criterion.

Image analysis is used to quantitatively characterise the ISO 4505-1978 standard charts with respect to volume fraction, number density and size distribution of defects. The results are compared to measured distributions for true microstructures.     

Betriebsmittelbezogene Lastmodellierung in Verteilungsnetzen

Übersicht Der Betriebszustand eines Verteilungsnetzes wird durch die Strombelastung aller Betriebsmittel beschrieben. Mit Hilfe einer statischen Estimationsmethode werden aus einzelnen Messungen und der Kenntnis der Verbrauchsdaten typische Verbraucherkurven (TVK) berechnet, die das elektrische Verhalten verschiedener Verbrauchergruppen widerspiegeln. Auf dieser Basis ist eine betriebsmittelbezogene Lastmodellierung an beliebigen Betriebsmitteln in Abhängigkeit der Verbraucherzusammensetzung unter Berücksichtigung externer Einflüsse wie der Temperatur möglich. Die so gewonnenen Belastungsverläufe erlauben eine Beschreibung des Netzzustands in den Verteilungsnetzen.

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Bus load modelling in distribution systems

Contents The operating state of a distribution system is determined by the bus load current. Based on individual substation measurements and the load composition typical load curves are calculated using statistical estimation theory. These typical load curves describe the electrical behaviour of the different load types (e.g. household, storage heating, commerce etc.). As soon as the typical load curves are determined it is possible to calculate the bus load current in any substation taking external influences such as temperature into consideration. The bus load current serve as load models which completely describe the operating state of the distribution system.

     

Inhibiting effects of serotonin and serotonin antagonists on the migration of mononuclear leucocytes

The effect of serotonin and the serotonin antagonists ketanserin, methiotepine and ICS-205-930 on the migration of leucocytes was studied by using the sealed capillary migration technique. The migration of mononuclear leucocytes was inhibited by serotonin at 10(-4) and 10(-6)-10(-10)mol/l. An inhibition of the mononuclear leucocyte migration was also caused by ICS-205-930 at 10(-4)mol/l, ketanserin at 10(-4) and 10(-8)-10(-10)mol/l and methiotepine at 10(-4) and 10(-6)-10(-8)mol/l. No inhibiting effects of serotonin or the serotonin antagonists were found on the migration of polymorphonuclear leucocytes. Thus, both serotonin and serotonin antagonists may inhibit mononuclear leucocyte migration.     

Finite element modelling of calendering — some aspects of the effects of temperature gradients and structure inhomogeneities

The compression of a paper web in a calender nip has been simulated using the finite element method. The mechanical properties of the paper were allowed to vary in the thickness and machine directions of the web. This was done in order to model the influence of temperature gradients as well as density variations (due to the presence of fibre floes) on the deformation behaviour in the nip. Paper was assumed to be an elastic-plastic material exhibiting strain hardening. The yielding behaviour was governed by the Drucker-Prager yield condition. Simulations of the deformation behaviour when paper was subjected to a temperature gradient, clearly revealed that the deformation gradually became more concentrated towards the surface layers as the temperature of the surface increased. This is in accordance with experimental results which indicate that temperature-gradient calendering promotes the surface properties, whereas the bulk of the structure is preserved. Modelling the deformation behaviour of a structure containing density variations reveals that the paper may contain an inhomogeneous strain distribution after unloading, i.e. after passage through the nip.     

Tocopherol contents of some Turkish wine by-products

The aim of this study was to determine the tocopherol contents of wine by-products including grape seed, pomace (seed, skin and stem) and bagasse (skin and stem) by using two different extraction methods in order to evaluate the possibilities of them as natural non-polar antioxidants. Cold extraction appeared to give more tocopherol contents in seeds than hot extraction. But hot extraction was found more suitable for pomace and bagasse. α-Tocopherol was the most abundant tocopherol in the grape seed, pomace and bagasse. Although γ- and δ-tocopherols were found in the samples with low concentrations, β-tocopherol was not detected in the samples. Kalecik karası had the highest α and total tocopherol compared to the other cultivars. On the other hand, hot extracted bagasse in all cultivars gave the highest tocopherol contents. As a conclusion, wine by-products, a large scale wastes, can be evaluated both to get natural tocopherol source and to obtain economical gain.     

Model Driven Architecture

Bei der Model Driven Architecture (MDA) bilden Modelle die zentralen Elemente des Softwareentwicklungsprozesses. Ziel ist es, plattformspezifische Modelle möglichst automatisiert aus plattformunabhängigen Modellen abzuleiten. Dadurch soll der Aufwand der Softwareentwicklung verringert und die Adaptierung an neue Technologien erleichtert werden.*Vorschläge an Prof. Dr. Frank Puppe oder Dieter Steinbauer Alle „Aktuellen Schlagwörter“ seit 1988 finden Sie unter: www.ai-wuerzburg.de/as