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排序方式: 共有677条查询结果,搜索用时 23 毫秒
71.
Das Auflösungsverhalten von gebranntem Dolomit wurde durch Schmelzversuche ermittelt, bei denen stahlwerksähnliche Schlakken mit einem Dolomittiegel reagierten. Die Auflösung des Tiegelmaterials in der Schlacke wurde dabei sowohl unter dem Aspekt des Schlackenbildners Dolomit als auch aus der Sicht MgO-haltigen Feuerfestmaterials ausgewertet. Es konnte verfolgt werden, wie die beiden unverbunden nebeneinander vorliegenden Hauptkomponenten des Dolomitkalks, CaO und MgO, entsprechend ihren jeweils treibenden Kräften, den Abständen zur Sättigung, unterschiedlich schnell in Lösung gehen. Trotz bevorzugter Auflösung des CaO erreicht das MgO wegen eines geringeren Abstandes zur Sättigung eher die Löslichkeitsgrenze, unterstützt durch den Effekt, daß bereits gelöstes CaO die MgO-Sättigungsgehalte erniedrigt, während umgekehrt MgO die CaO-Löslichkeit zunächst durch Zurückdrängen der Dicalciumsilikat-Ausscheidung (?C2S-Nase”) deutlich, dann an der eigentlichen Kalksättigung noch leicht erhöht. Die Auflösung kommt durch eine rasche Sättigung an MgO zwar nicht völlig zum Stillstand, wird aber stark verlangsamt, so daß die metallurgisch wichtige Kalksättigung bei alleinigem Einsatz von Dolomitkalk als Schlackenbildner nicht erreicht werden kann. Darüberhinaus wird die Schlacke infolge der Übersättigung an MgO heterogen und viskos. Die Auflösung von magnesitischem Feuerfestmaterial konnte simuliert werden, indem nur das Verhalten der MgO-Komponente des Dolomits zu Beginn des Versuchs betrachtet wurde. Die verschleißmindernde Wirkung von MgO-Vorgaben zur angreifenden Schlacke wurde nachgewiesen. Ferner konnten durch Annahme einer diffusionsgesteuerten Auflösung in der ersten Phase des Versuchs Stoffübergangskoeffizienten des CaO und des MgO gewonnen werden. 相似文献
72.
The transport of corrosive liquids containing solids, in conventional energy and process technology as, for example, in oil and gas production, places high demands on the selection of materials for plant construction. A discussion on the chemo-mechanical load demonstrates the significance of hydrodynamics in selecting the test method. Choosing a pipe with an abrupt expansion of cross-section as a flow model yields a new method of simulating operation conditions. By subjecting ferrous materials used for hydraulic machinery to representative media from three important industries, a broad spectrum of results can be obtained. Classification of the results leads to four basic types of mass loss behaviour in materials as functions of flow rate. These findings yield guidelines for the selection of materials and the dimensioning of flow equipment. 相似文献
73.
Ingo Wolff 《国际射频与微波计算机辅助工程杂志》1991,1(2):117-142
A comparison of different methods for the characterization of planar line discontinuities with emphasis on microstrip discontinuities is given, thereby describing the present state of the art in this area of microwave circuit CAD. Quasi-static equivalent circuit models, the magnetic wall waveguide model of microstrip discontinuities, full-wave analysis techniques like the orthogonal series expansion and mode matching techniques, the spectral domain analysis technique using roof-top functions, and the finite-difference time-domain technique are described briefly and compared with respect to their numerical efficiency and their capabilities. 相似文献
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Bianchi M Herrero DL Valle F Greco P Ingo GM Kaciulis S Biscarini F Cavallini M 《Nanotechnology》2011,22(35):355301
We propose an integrated top-down and bottom-up approach to single-step nanofabrication of complex nanostructures made of different materials. The process, termed lithographically controlled etching (LCE), starts with a drop of an etching solution cast on the surface to be patterned. By placing a polymeric mold on the substrate, the stamp protrusions come into contact with the surface, thus protecting it, whereas the surface beneath the mold recesses is exposed to a thin layer of etching solution, allowing the surface to be etched. By dispersing nanoparticles into the etching solution, these can be deposited and self-organize in the recesses on the substrate as these are excavated. We demonstrate here the fabrication of complex structures and nanowires 30 nm wide. Moreover, by exploiting capillary forces, it is possible to deposit nanoparticles at precise positions with respect to optically addressable microstructures, thus realizing a multiscale functional pattern. 相似文献
78.
Pooled versus separate measurements of tree-ring stable isotopes 总被引:1,自引:0,他引:1
Dorado Liñán I Gutiérrez E Helle G Heinrich I Andreu-Hayles L Planells O Leuenberger M Bürger C Schleser G 《The Science of the total environment》2011,409(11):2244-2251
δ13C and δ18O of tree rings contain time integrated information about the environmental conditions weighted by seasonal growth dynamics and are well established as sources of palaeoclimatic and ecophysiological data. Annually resolved isotope chronologies are frequently produced by pooling dated growth rings from several trees prior to the isotopic analyses. This procedure has the advantage of saving time and resources, but precludes from defining the isotopic error or statistical uncertainty related to the inter-tree variability. Up to now only a few studies have compared isotope series from pooled tree rings with isotopic measurements from individual trees. We tested whether or not the δ13C and the δ18O chronologies derived from pooled and from individual tree rings display significant differences at two locations from the Iberian Peninsula to assess advantages and constraints of both methodologies. The comparisons along the period 1900-2003 reveal a good agreement between pooled chronologies and the two mean master series which were created by averaging raw individual values (Mean) or by generating a mass calibrated mean (MassC). In most of the cases, pooled chronologies show high synchronicity with averaged individual samples at interannual scale but some differences also show up especially when comparing δ18O decadal to multi-decadal variations. Moreover, differences in the first order autocorrelation among individuals may be obscured by pooling strategies. The lack of replication of pooled chronologies prevents detection of a bias due to a higher mass contribution of one sample but uncertainties associated with the analytical process itself, as sample inhomogeneity, seems to account for the observed differences. 相似文献
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Ingo Wegener 《Information Processing Letters》2002,83(1):17-19
The computation of the strongly connected components of a directed graph is one of the fundamental algorithmic graph problems. Linear-time algorithms with simple implementations are known. Here a simplified correctness proof for one of these algorithms is presented. 相似文献