A robotic fish driven by oscillating fins, 'Cownose Ray-I', is developed, which is in dorsoventrally flattened shape without a tail. The robotic fish is composed of a body and two lateral fins. A three-factor ...A robotic fish driven by oscillating fins, 'Cownose Ray-I', is developed, which is in dorsoventrally flattened shape without a tail. The robotic fish is composed of a body and two lateral fins. A three-factor kinematic model is established and used in the design of a mechanism. By controlling the three kinematic parameters, the robotic fish can accelerate and maneuver. Forward velocity is dependent on the largest amplitude and the number of waves in the fins, while the relative contribution of fin beat frequency to the forward velocity of the robotic fish is different from the usual result. On the other hand, experimental results on maneuvering show that phase difference has a stronger effect on swerving than the largest amplitude to some extent. In addition, as propulsion waves pass from the trailing edge to the leading edge, the robotic fish attains a backward velocity of 0. 15 m·s^(-1).展开更多
In order to avoid single-phase adaptive reclosure overlap in a permanent fault,accurate identification of the fault types on transmission line is necessary.We present a fault nature identification method for ultra-hig...In order to avoid single-phase adaptive reclosure overlap in a permanent fault,accurate identification of the fault types on transmission line is necessary.We present a fault nature identification method for ultra-high voltage alternating current(UHVAC) transmission lines with shunt reactor.The voltage amplitude ratios of the neutral small reactance voltage to terminal voltage under transient fault and permanent fault are calculated.The significant differences of the ratio under the two faults have been analyzed.It is found that the ratio can be a criterion to distinguish the fault type,transient or permanent,accurately.Additionally,we also proposed a method that delays a beat frequency oscillation cycle to decide the fault types for the existence of beat frequency oscillation which will cause misidentification on transient faults.Abundant simulation results of ATP/EMTP show that the voltage amplitude ratio under transient fault is between 0.6 and 0.7,which is bigger than 2.5,the ratio under permanent fault.展开更多
基金The supports of National Natural Science Foundation of China (No.50405006)the supports of the innovation foundation of graduate students of National University of Defense Technology (No.B060302) are also gratefully acknowledged
文摘A robotic fish driven by oscillating fins, 'Cownose Ray-I', is developed, which is in dorsoventrally flattened shape without a tail. The robotic fish is composed of a body and two lateral fins. A three-factor kinematic model is established and used in the design of a mechanism. By controlling the three kinematic parameters, the robotic fish can accelerate and maneuver. Forward velocity is dependent on the largest amplitude and the number of waves in the fins, while the relative contribution of fin beat frequency to the forward velocity of the robotic fish is different from the usual result. On the other hand, experimental results on maneuvering show that phase difference has a stronger effect on swerving than the largest amplitude to some extent. In addition, as propulsion waves pass from the trailing edge to the leading edge, the robotic fish attains a backward velocity of 0. 15 m·s^(-1).
基金Project supported by National Natural Science Foundation of China(51177104)Liaoning Provincial National Natural Science Foundation of China(201102169)
文摘In order to avoid single-phase adaptive reclosure overlap in a permanent fault,accurate identification of the fault types on transmission line is necessary.We present a fault nature identification method for ultra-high voltage alternating current(UHVAC) transmission lines with shunt reactor.The voltage amplitude ratios of the neutral small reactance voltage to terminal voltage under transient fault and permanent fault are calculated.The significant differences of the ratio under the two faults have been analyzed.It is found that the ratio can be a criterion to distinguish the fault type,transient or permanent,accurately.Additionally,we also proposed a method that delays a beat frequency oscillation cycle to decide the fault types for the existence of beat frequency oscillation which will cause misidentification on transient faults.Abundant simulation results of ATP/EMTP show that the voltage amplitude ratio under transient fault is between 0.6 and 0.7,which is bigger than 2.5,the ratio under permanent fault.
