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Viscosities and liquid structure of alloys Cu75Al25, Cu87Sn13 and Al-12.5%Si and pure metals Cu and Sn are investigated by using torsional oscillation viscometry and high temperature x-ray diffractometry. The viscosities of pure metals and eutectic alloy melts along with the short-range order structure are found to follow the Arrhenius law in a wide range of temperature above the liquidus. The breakpoints in Arrhenius plots emerge when the structures of alloy melts are transformed from the medium-range order structure to the short-range order structure. It has been found that the change of the viscosity of the metallic alloys is a characteristic of microstructure transformation in the related melts. 相似文献
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时间自适应支持向量机(TA-SVM)方法在处理非静态数据集时表现出良好的性能,但仅根据邻接子分类器相似而获得的相关信息并不充分,由此可能会导致训练所得模型不可靠,限制其应用能力.该文通过定义子分类器序列的相关性衰减函数,提出新的面向非静态数据分类问题的演进支持向量机(Evolving Support Vector Machines, ESVM).ESVM 使用衰变函数以体现子分类器之间的相关程度,通过约束所有子分类器之间的带权差异以求得变化更光滑的子分类器序列,契合了数据中隐藏的渐变概念.在各种数据缓慢变化场景的对比实验中,该文的 ESVM 方法优于 TA-SVM 方法. 相似文献
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This paper reports that anomalous local order in
liquid and glassy AlFeCe alloy has been detected by x-ray
diffraction measurements. The addition of the element Ce has a great
effect on this local structural order. The element Ce favours
interpenetration of the icosahedra by sharing a common face and
edges. It argues that frustration between this short-range order
and the long-range crystalline order controls the glass-forming
ability of these liquids. The obtained results suggest that a system
having a stronger tendency to show local icosahedral order should be
a better glass-former. This scenario also naturally explains the
close relationship between the local icosahedral order in a liquid,
glass-forming ability, and the nucleation barrier. Such topological
local order has also been analysed directly using the reverse Monte
Carlo method. It also estimated the fraction of local ordered and
disordered structural units in a glassy AlFeCe alloy. 相似文献
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We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I - V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. 相似文献