Experimental determination of the jet effect for blowing oxygen into the melting bath of electric arc furnaces

Recent practice with electric arc furnaces has been the injection of oxygen through nozzle positioned on the bottom of the furnace. This type of furnace places certain requirements on bottom injection. To enable a constant coupling of the energy over the electrodes, a calm bath surface must be guaranteed. On the other hand, a good mixing of the bath is required to avoid any thermal lamination in the bath. The latter condition in particular is prerequisite for a maximum melting capacity. When judging the effect of the jet on the bath, it must be taken into account that the oxygen disintegrates directly after entering the bath and merely transfers its impulse to the liquid melt. This jet effect is described by the calculation method introduced below which is adjusted to the actual behaviour using simulation tests. In this connection, changes in the jet consistency caused by the formation of carbon monoxide have not yet been considered. Parallel to this, the mixing of the bath was determined by conductivity measurements. In these experiments, the bath level x_f, the vessel diameter D and the blown-in water mass-flux m_w were changed. A comparison of the results for fountain height and mixing time formed the basis for the development of an optimization concept for bottom-blowing nozzles in electric arc furnaces.     

Influence of oxide scales on heat transfer in secondary cooling zones in the continuous casting process,part 2: determination of material properties of oxide scales on steel under spray-water cooling conditions

In order to model heat transfer from the slab to the cooling agent in the continuous casting process the thermophysical properties of the surface layer must be taken into account. For this purpose thermal conductivities and thermal diffusivities of wustite as well as of two carbon steels were measured. The oxide scale growth for six steels was measured as a function of time and at temperatures between 900 and 1200°C in air and in steam. Complex heterogeneous oxide scales were examined by optical and scanning electron microscopy, by SIMS, as well as by Mössbauer spectroscopy. Segregation of alloying elements in the metal-oxide contact zone was found. Cracks due to thermal stresses result in spalling of the scale. Therefore, a straightforward use of the data for process modelling can principally not be recommended without restrictions.     

Life stressors, personal and social resources, and depression: A 4-year structural model.

By extending earlier stress-resistance research with a 1-yr time lag, findings with 254 adults show that adaptive personality characteristics and positive family support operate prospectively over 4 yrs in predicting reduced depression even when prior depression is controlled. By strengthening knowledge about the determinants and mediational role of coping, the results demonstrate in a 2-group LISREL analysis that the pattern of predictive relations differs under high and low stressors. Under high stressors, personal and social resources relate to future psychological health indirectly, through more adaptive coping strategies. Under low stressors, these resources relate directly to psychological health. The results support the idea that such resources play a causal role in maintaining psychological health, and they suggest the potential for a general, adaptively oriented framework applicable to adjustment under both high and low stressors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial Non-Cyclic Geometric Phase in Neutron Interferometry

We present a split-beam neutron interferometric experiment to test the non-cyclic geometric phase tied to the spatial evolution of the system: the subjacent two-dimensional Hilbert space is spanned by the two possible paths in the interferometer and the evolution of the state is controlled by phase shifters and absorbers. A related experiment was reported previously by some of the authors to verify the cyclic spatial geometric phase. The interpretation of this experiment, namely to ascribe a geometric phase to this particular state evolution, has met severe criticism. The extension to non-cyclic evolution manifests the correctness of the interpretation of the previous experiment by means of an explicit calculation of the non-cyclic geometric phase in terms of paths on the Bloch-sphere. The theoretical treatment comprises the cyclic geometric phase as a special case, which is confirmed by experiment.     

Preparation of aqueous polyaniline dispersions by micellar‐aided polymerization

Polyaniline (PAn) dispersed in water was prepared with sodium dodecylsulfonate (SDS) as a surfactant with varying concentrations of aniline and HCl and molar ratios of SDS/aniline. The PAn dispersion was homogeneous and stable, and its pH value could be adjusted. The conductivity of PAn powder, precipitated from this dispersion, was as high as 20 S/cm. The transmission electron microscopy morphology of PAn assembled in the dispersion was particle‐like, fiber‐like, or coil‐like, depending on the initial concentration of SDS and aniline. The polymerization of aniline was accelerated by SDS, which was confirmed by open‐circuit potential measurement during the polymerization process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1550–1555, 2003     

Das Schwinden und seine Beziehungen zu Rohwichte und Aufbau des Holzes

Zusammenfassung Einleitend werden Rohwiechte und Holzfeuchtigkeit als grundlegende Weiser technisch wichtiger Holzeigenschaften behandelt und die physikalischen Vorg?nge beim Zutrift von Wasser zu Holz erl?utert, die für die Untersuchung des Schwindvorganges von besonderer Bedeutung sind. Die Zusammenh?nge zwischen Luftfeuchtigkeit, Temperatur und Holzfeuehtigkeit k?nnen durch Einführung des S?ttigungsgrades der Luft an Stelle der relativen Luftfeuchtigkeit vereinfacht dargestellt werden (Bild 3). Die Raumquellung des Holzes kann bei vorangegangener vorsichtiger Mitteilung aus dem Mechanisch-technologischen Institut der Reichsanstalt für Holzforschung.     

Microstructural Coarsening During Sintering of Boron Carbide

The sintering behavior of boron carbide was investigated with particular attention given to microstructure development at various stages in the sintering process. Hot-pressing and pressureless sintering techniques were employed and the effects of heating rate, firing atmosphere, and composition were used to characterize the sintering behavior. Pressureless sintering at temperatures up to 2300°C produces only limited densification. Microstructural coarsening is responsible for this since it leads to conditions where densification is slow. Hot-pressing and carbon additions suppressed coarsening and permitted densification to >95% of theoretical density.     

Drinking to cope and alcohol use and abuse in unipolar depression: A 10-year model.

This study examined drinking to cope with distress and drinking behavior in a baseline sample of 412 unipolar depressed patients assessed 4 times over a 10-year period. Baseline drinking to cope operated prospectively as a risk factor for more alcohol consumption at 1-, 4, and 10-year follow-ups and for more drinking problems at 1- and 4-year follow-ups. Findings elucidate a key mechanism in this process by showing that drinking to cope strengthened the link between depressive symptoms and drinking behavior. Individuals who had a stronger propensity to drink to cope at baseline showed a stronger connection between depressive symptoms and both alcohol consumption and drinking problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)