This study presents and verifies a new idea for constructing a rotary traveling wave ultrasonic motor （USM） that uses the radial bending mode of a ring. In the new design, 20 trapezoid cross section slots are cut sy...This study presents and verifies a new idea for constructing a rotary traveling wave ultrasonic motor （USM） that uses the radial bending mode of a ring. In the new design, 20 trapezoid cross section slots are cut symmetrically in the outer surface of a thick duralumin alloy ring, where 20 PZT stacks are nested. In each slot, two wedging blocks are set between the PZT stack and the two sides of the slot respectively to apply preloading on the PZT ceramics. Two radial bending modes of the stator that have a phase difference of a quarter wavelength on space are generated by using the d33 operating mode of the PZT elements, and then a flexural traveling wave is formed by the superimposing of two standing waves whose amplitudes are equal and phases are different by 90~ temporally. Two conical rotors are pressed to each end of the ring type stator by a coiled spring. The finite element method （FEM） simulation is developed to validate the feasibility of the proposed motor. The maximal speed and torque of the prototype are tested to be 126 r/rain and 0.8 N＇m, respectively.展开更多
In this research, we introduce a new heuristic approach using the concept of ant colony optimization （ACO） to extract patterns from the chromosomes generated by previous generations for solving the generalized trave...In this research, we introduce a new heuristic approach using the concept of ant colony optimization （ACO） to extract patterns from the chromosomes generated by previous generations for solving the generalized traveling salesman problem. The proposed heuristic is composed of two phases. In the first phase the ACO technique is adopted to establish an archive consisting of a set of non-overlapping blocks and of a set of remaining cities （nodes） to be visited. The second phase is a block recombination phase where the set of blocks and the rest of cities are combined to form an artificial chromosome. The generated artificial chromosomes （ACs） will then be injected into a standard genetic algorithm （SGA） to speed up the convergence. The proposed method is called ＂Puzzle-Based Genetic Algorithm＂ or ＂p-ACGA＂. We demonstrate that p-ACGA performs very well on all TSPLIB problems, which have been solved to optimality by other researchers. The proposed approach can prevent the early convergence of the genetic algorithm （GA） and lead the algorithm to explore and exploit the search space by taking advantage of the artificial chromosomes.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 50875057 and 51105097)the State Key Laboratory of Robotics and Systems (No. SKLRS200901A04), China
文摘This study presents and verifies a new idea for constructing a rotary traveling wave ultrasonic motor （USM） that uses the radial bending mode of a ring. In the new design, 20 trapezoid cross section slots are cut symmetrically in the outer surface of a thick duralumin alloy ring, where 20 PZT stacks are nested. In each slot, two wedging blocks are set between the PZT stack and the two sides of the slot respectively to apply preloading on the PZT ceramics. Two radial bending modes of the stator that have a phase difference of a quarter wavelength on space are generated by using the d33 operating mode of the PZT elements, and then a flexural traveling wave is formed by the superimposing of two standing waves whose amplitudes are equal and phases are different by 90~ temporally. Two conical rotors are pressed to each end of the ring type stator by a coiled spring. The finite element method （FEM） simulation is developed to validate the feasibility of the proposed motor. The maximal speed and torque of the prototype are tested to be 126 r/rain and 0.8 N＇m, respectively.
文摘In this research, we introduce a new heuristic approach using the concept of ant colony optimization （ACO） to extract patterns from the chromosomes generated by previous generations for solving the generalized traveling salesman problem. The proposed heuristic is composed of two phases. In the first phase the ACO technique is adopted to establish an archive consisting of a set of non-overlapping blocks and of a set of remaining cities （nodes） to be visited. The second phase is a block recombination phase where the set of blocks and the rest of cities are combined to form an artificial chromosome. The generated artificial chromosomes （ACs） will then be injected into a standard genetic algorithm （SGA） to speed up the convergence. The proposed method is called ＂Puzzle-Based Genetic Algorithm＂ or ＂p-ACGA＂. We demonstrate that p-ACGA performs very well on all TSPLIB problems, which have been solved to optimality by other researchers. The proposed approach can prevent the early convergence of the genetic algorithm （GA） and lead the algorithm to explore and exploit the search space by taking advantage of the artificial chromosomes.
