A novel high-speed parallel kinematic machine （PKM） named Delta-S parallel manipulator is proposed, which consists of a fixed base connected to a moving platform through three limbs with identical topology. Each lim...A novel high-speed parallel kinematic machine （PKM） named Delta-S parallel manipulator is proposed, which consists of a fixed base connected to a moving platform through three limbs with identical topology. Each limb is composed of one driving ann and one follower arm, herein, the latter includes two strings and one middle rod, all located in a same plane. Compared with similar manipulators with uniform parameters, the novel and unique topology as well as the addition of two strings of Delta-S manipulator can remove the clearance of the spherical joints, reduce the inertial load of components further, improve the positioning accuracy and dynamic performance, and so on. In order to formulate the kineto-static model of Delta-S manipulator, the kineto-static analyses and models of the driving arm, the generalized follower and the moving platform can be carried out by the D＇ALEMBERT principle. For the sake of obtaining the force analytic results of strings, the deformation compatibility condition of strings and the middle rod are determined. Furthermore, in virtue of the assumption of small deformation and the linear superposition principle, the minimal pre-tightening force of the strings is calculated. The main results include that the loads of the strings and the middle rod must be larger than ＂zero＂ and the pre-tightening force over the workspace must be larger than the minimal pre-tightening force at any time within the workspace, which lay the foundation for the dynamic analysis and the prototype manufacture of the Delta-S manipulator.展开更多
Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from expe...Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from experimental in- vestigation. Binding energy calculations suggest that the boron structure designed from theory is more stable than that made by experiment. Elastic constants calculations show that both structures are mechanically stable. The electronic structure results show that the theoretical designed structure exhibits semi-metal behavior, while the other structure exhibits metMlic character. No magnetic phenomenal is discovered from them. All the calculations are carried out by the first principles calculation through the MatC1oud platform, which is developed by our research group.展开更多
基金Projects(50175295,50675151) supported by the National Natural Science Foundation of ChinaProject(11JCZDJC22700) supported by Tianjin Science and Technology Program,ChinaProject(2007AA042001) supported by the National High Technology Research and Development Program of China
文摘A novel high-speed parallel kinematic machine （PKM） named Delta-S parallel manipulator is proposed, which consists of a fixed base connected to a moving platform through three limbs with identical topology. Each limb is composed of one driving ann and one follower arm, herein, the latter includes two strings and one middle rod, all located in a same plane. Compared with similar manipulators with uniform parameters, the novel and unique topology as well as the addition of two strings of Delta-S manipulator can remove the clearance of the spherical joints, reduce the inertial load of components further, improve the positioning accuracy and dynamic performance, and so on. In order to formulate the kineto-static model of Delta-S manipulator, the kineto-static analyses and models of the driving arm, the generalized follower and the moving platform can be carried out by the D＇ALEMBERT principle. For the sake of obtaining the force analytic results of strings, the deformation compatibility condition of strings and the middle rod are determined. Furthermore, in virtue of the assumption of small deformation and the linear superposition principle, the minimal pre-tightening force of the strings is calculated. The main results include that the loads of the strings and the middle rod must be larger than ＂zero＂ and the pre-tightening force over the workspace must be larger than the minimal pre-tightening force at any time within the workspace, which lay the foundation for the dynamic analysis and the prototype manufacture of the Delta-S manipulator.
基金Supported by National Natural Science Foundation of China under Grant No.11547177
文摘Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from experimental in- vestigation. Binding energy calculations suggest that the boron structure designed from theory is more stable than that made by experiment. Elastic constants calculations show that both structures are mechanically stable. The electronic structure results show that the theoretical designed structure exhibits semi-metal behavior, while the other structure exhibits metMlic character. No magnetic phenomenal is discovered from them. All the calculations are carried out by the first principles calculation through the MatC1oud platform, which is developed by our research group.
