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排序方式: 共有683条查询结果,搜索用时 46 毫秒
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Zeitschrift für Physik A Hadrons and nuclei - Berechnung der Dichteverteilung als Funktion der Höhe und der Zeit in einer Lösung endlicher Höhe unter der Wirkung von Schwere und... 相似文献
43.
Yang Xu Christian Axt Minhang Song Reinhold Kneer Shuiqing Li 《Proceedings of the Combustion Institute》2021,38(3):4179-4188
This paper intensively investigated the ignition of turbulent coal flames in a novel fully-mixed tubular swirl burner. The Nikon D300s digital camera was used to capture the statistical ignition behavior of dispersed coal particle streams in different ambiences. Meanwhile, the combustion dynamics of individual coal particles were also recorded by means of high-speed photography. Two low-rank coal samples, Hulunbel lignite and Zhundong coal, were tested in this study. The ignition delay times of coal particles in the swirl burner were compared with those in a flat-flame burner. In contrast to previous work on a laminar flat-flame burner, the current experimental results show that the turbulent ambience significantly enhances the ignition of all coal samples, which is exceptionally pronounced under high temperature and low oxygen conditions. In addition, the sensitivity analysis suggests that both the enhanced heat and mass transfer contribute to the early ignition in turbulence. The effect of elevated mass transfer coefficient turns prominent in low oxygen fraction ambience, wherein the volatile barrier effect is suppressed by the enhanced mixing process. The combined effect of turbulence favors the shifting of ignition modes to the heterogeneous-dominant region. Last but not least, the ceased volatile flame that visualized in turbulent low oxygen ambience further confirms the important role of heterogeneous ignition. 相似文献
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Mark S. Oliver Kay Y. Blohowiak Reinhold H. Dauskardt 《Journal of Sol-Gel Science and Technology》2010,55(3):360-368
The mechanical reliability of hybrid films depends critically on their fracture properties which are controlled largely by
the film composition and molecular structure. We have investigated the adhesive and cohesive fracture properties of hybrid
films processed from 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetra n-propoxyzirconium (TPOZ), for which the roles of molecular structure and composition have not been well established. The influences
of film Zr/GPTMS ratio, silane crosslinking, and substrate composition on fracture resistance were quantified in terms of
the critical strain energy release rate, GC Film fracture energy was found to increase, then decrease with increasing Zr/GPTMS ratio. Removal of the epoxy rings of GPTMS
from the film was found to drastically decrease the cohesive fracture energy of the film as well as the adhesive fracture
energy of the film/epoxy interface. Finally, films deposited on silicon had much higher fracture energies compared to those
deposited onto aluminum and titanium from identical sols. FTIR, XPS, and AFM were used to characterize the film structure
and fracture surfaces. The molecular-scale mechanisms responsible for the observed trends are discussed. These results provide
new insights into the interaction between the substrate chemistry, molecular structure, and mechanical reliability of hybrid
sol-gel films. 相似文献
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Reinhold Baer 《Mathematische Zeitschrift》1962,79(1):344-363
Ohne Zusammenfassung 相似文献
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Klaus Günther Alex von Bohlen Gerhard Paprott Reinhold Klockenkämper 《Fresenius' Journal of Analytical Chemistry》1992,342(4-5):444-448
Summary Total-reflection X-ray fluorescence (TXRF) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the analysis of two biological reference materials. The quantifications were carried out after addition of one single standard element which serves as an internal standard in both cases. The results of TXRF analysis were good to satisfactory. The method is therefore suitable for fast multielement analysis, because it needs no special calibration specimens. The results of ICP-MS analysis are at least in the order of magnitude of the certified values. In some cases recoveries fit very well. For quantitative analysis, however, the use of the standard addition method or the calibration with external standards is required. 相似文献
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