The relevance-adaptation theory can be said to be a combination of relevance theory and adaptation theory.It is a kind of cognition of context.Generally speaking,cognition context is a kind of mental cognition,which b...The relevance-adaptation theory can be said to be a combination of relevance theory and adaptation theory.It is a kind of cognition of context.Generally speaking,cognition context is a kind of mental cognition,which belongs to a form of mental structure recognition,relating to the knowledge,understanding and relevance of discourse information in this context.This article mainly elaborates the operation mechanism of relevance and adaptation theory and the comparison of relevance of College English Test Band 4 and 6.This can be used as a reference for relevant academic staff.展开更多
The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact...The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose "tips" are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional "stagger ridge" structure.展开更多
文摘The relevance-adaptation theory can be said to be a combination of relevance theory and adaptation theory.It is a kind of cognition of context.Generally speaking,cognition context is a kind of mental cognition,which belongs to a form of mental structure recognition,relating to the knowledge,understanding and relevance of discourse information in this context.This article mainly elaborates the operation mechanism of relevance and adaptation theory and the comparison of relevance of College English Test Band 4 and 6.This can be used as a reference for relevant academic staff.
基金Project (51001014) supported by the Young Scientists Fund of the National Natural Science Foundation of China
文摘The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose "tips" are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional "stagger ridge" structure.