共查询到13条相似文献,搜索用时 6 毫秒
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RB Zhang 《Canadian Metallurgical Quarterly》1985,31(6):1512-1514
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Yield vertices for {123}〈111〉 multiple slip 总被引:1,自引:0,他引:1
Z. Y. Chen X. M. Zhang Z. P. Zhou C. M. Liu S. Li 《Metallurgical and Materials Transactions A》2000,31(10):2449-2456
The single-crystal yield surfaces of bcc crystals for slip on {123}〈111〉 systems have been analyzed systematically and derived
based on the Taylor/Bishop-Hill theory. It is found that there are 338 stress states altogether. All the stress states are
classified according to the crystal symmetry. The results demonstrated that there are 14 groups of yield vertices, which activate
five, six, or eight slip systems, depending on the crystallographically none quivalent groups. In addition, the four groups
of yield vertices that Chin and Wonsiewicz[15] did not consider have been obtained (there are 126 stress states). Among all these vertices, the fraction of vertices for
which there is slip ambiguity (more than five active slip systems) is reduced considerably to 146/338 (≈43 pct). By means
of the stress states obtained by Chin et al. and by the present authors, respectively, the plastic flow for axially symmetric deformation and three-axial deformation
have been analyzed. In the case of axially symmetric deformation, the results are the same using the two different kinds of
stress states. The obtained new stress states are necessary in order to analyze the three-axial deformation. 相似文献
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《Acta Metallurgica Materialia》1992,40(12):3239-3248
The equation describing surface topographic evolution by surface diffusion is adapted to describe the thermal pitting of a surface in the vicinity of a grain boundary vertex (triple junction of three boundaries) in order to model experimental observations of hole formation in thin films; isotropy of surface properties is assumed. An analytic solution for the evolution of an initially flat surface is obtained for a sector between two intersecting boundaries (of a triple junction) with an included angle ϕ=90°, and numerical solutions are calculated for several other values of ϕ. The results show that the surface shape is time-independent with linear dimensions that are proportional to . For a given angle at the root of the groove, the calculations show that the rate of pit deepening increases as ϕ decreases and show that, typically, pitting is appreciably faster than thermal grooving. 相似文献
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冶成福 《Canadian Metallurgical Quarterly》2011,43(1)
具有r个悬挂点的树称为r叶树.研究了具有n个顶点的4叶和5叶树的Hosoya 指标值,刻画了具有最大和最小Hosoya指标的5叶树和最小Hosoya指标的4叶树. 相似文献
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In 2 experiments, observers (n?=?17) searched for a misaligned vertex in displays depicting 1 or more two-dimensional (2-D), three-dimensional (3-D), and quasi-3-D objects that were drawn with unconnected vertices. Serial search functions were obtained for all 3 conditions, even after much practice. In addition, search among the 2-D objects was more efficient than search among either 3-D or quasi-3-D objects, which did not differ after practice. This finding suggests that differences in depicted dimensionality cannot explain the difference in performance between the 2-D and 3-D conditions, but differences in stimulus complexity can. Further, after practice with the 2-D displays, observers could detect a misaligned vertex as rapidly among 2 objects as they could with 1-object displays. These findings have implications for models of object recognition that assign a critical role to vertices in early vision, as well as the notion that mechanisms underlying preattentive processing may differ from those underlying the automaticity of processing that develops with practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献