The 2024/3003 aluminum gradient alloys are prepared by semi continuous casting. The influences of throttle bore diameter of embedded nozzle and temperature of internal melt on composition distribution, macrostructure,...The 2024/3003 aluminum gradient alloys are prepared by semi continuous casting. The influences of throttle bore diameter of embedded nozzle and temperature of internal melt on composition distribution, macrostructure, hardness are analyzed, and the stability of gradient distribution of composition, macrostructure and hardness along the axial direction of the ingot is also studied. The results show that diffe rent composition profiles can be achieved by adjusting the processing parameters; the volume fraction of inner alloy in the ingot can be increased by enlarging the throttle bore diameter and elevating the temperature of inner melt; quasi steady solidification can be realized within 20 s during cast processing, and consistent quality ingot is obtained by controlling the casting speed and liquid height of inner melt.展开更多
The minimal continued fraction of m (where 0<m∈Z is not a square) is connected with the corresponding simple continued fraction, from which it can be written out.In this paper, it is shown that the minimal conti...The minimal continued fraction of m (where 0<m∈Z is not a square) is connected with the corresponding simple continued fraction, from which it can be written out.In this paper, it is shown that the minimal continued fraction is periodic, its period is shorter than twice of the period of the corresponding simple continued fraction, its absolute\|period is not greater than the period of the corresponding simple continued fraction.Several properties of the minimal continued fraction are also obtained.展开更多
文摘The 2024/3003 aluminum gradient alloys are prepared by semi continuous casting. The influences of throttle bore diameter of embedded nozzle and temperature of internal melt on composition distribution, macrostructure, hardness are analyzed, and the stability of gradient distribution of composition, macrostructure and hardness along the axial direction of the ingot is also studied. The results show that diffe rent composition profiles can be achieved by adjusting the processing parameters; the volume fraction of inner alloy in the ingot can be increased by enlarging the throttle bore diameter and elevating the temperature of inner melt; quasi steady solidification can be realized within 20 s during cast processing, and consistent quality ingot is obtained by controlling the casting speed and liquid height of inner melt.
基金Supported by the Science Foundation of Tsinghua Uni-versity
文摘The minimal continued fraction of m (where 0<m∈Z is not a square) is connected with the corresponding simple continued fraction, from which it can be written out.In this paper, it is shown that the minimal continued fraction is periodic, its period is shorter than twice of the period of the corresponding simple continued fraction, its absolute\|period is not greater than the period of the corresponding simple continued fraction.Several properties of the minimal continued fraction are also obtained.
