2,312 publications from this institution
Diffusion behavior of Nb in elemental powder metallurgy high Nb containing TiAl alloys was investigated. The results show that Nb element dissolves into the matrix by diffusion. Pore nests are formed in situ after Nb diffusion. With the increase in hot pressing temperature, the diffusion of Nb will be more sufficient, and the microstructure is more homogeneous. Nb element diffuses completely at 1400°C. Meanwhile, compression deformation and agglomeration phenomena of pores are observed in some pore nests. Hot isostatic pressing (HIP) treatment can only efficiently decrease but not eliminate porosity completely.
Describes a graphical approach to stability analysis for a two-link flexible-joint robot arm model controlled by a fuzzy proportional-integral-derivative (PID) controller developed by the present authors. This new fuzzy PID controller preserves the simple linear structure of its conventional counterpart yet enhances its self-tuning control capability, thereby significantly improving tracking control performance. A simulation result on a two-link flexible-joint robot arm model is included to visualize such satisfactory performance. A simple and realistic sufficient condition for the stability of the overall feedback control system is then derived from a graphical approach, giving a safe region for design, on which the fuzzy PID controlled robot arm system have guaranteed stability.
