Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of ...Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.展开更多
Route choice is a fundamental requirement in the evacuation process. The aim of this paper is to identify a method to simulate crowds in large indoor spaces with consideration of the acoustic system. This paper first ...Route choice is a fundamental requirement in the evacuation process. The aim of this paper is to identify a method to simulate crowds in large indoor spaces with consideration of the acoustic system. This paper first extends an existing cellular automaton model and proposes a ceUutar automaton crowd route choice model （CACR model） to simulate evacuees in large indoor spaces. It then defines a measure for evaluating the utility of evacuation time using the CACR model under different circumstances, such as a fire situation or different voice warning systems, which other commercial models cannot simulate. The analysis of the characteristics of a sound field in large indoor spaces is based on field measurements. An observation experiment in a gymnasium is employed to test the proposed model in a stadium evacuation scenario. The results demonstrate that the CACR model can accurately simulate the evacuation process in large indoor spaces under various circumstances.展开更多
基金Acknowledgments The authors acknowledge the financial support from the National Natural Science Foundation of China （Nos. 51001001 and 51201002）. Prof. Y.M. Wang and Dr. H. Li are kindly thanked for helpful discussion and proof reading.
文摘Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.
文摘Route choice is a fundamental requirement in the evacuation process. The aim of this paper is to identify a method to simulate crowds in large indoor spaces with consideration of the acoustic system. This paper first extends an existing cellular automaton model and proposes a ceUutar automaton crowd route choice model （CACR model） to simulate evacuees in large indoor spaces. It then defines a measure for evaluating the utility of evacuation time using the CACR model under different circumstances, such as a fire situation or different voice warning systems, which other commercial models cannot simulate. The analysis of the characteristics of a sound field in large indoor spaces is based on field measurements. An observation experiment in a gymnasium is employed to test the proposed model in a stadium evacuation scenario. The results demonstrate that the CACR model can accurately simulate the evacuation process in large indoor spaces under various circumstances.
