A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yie...A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yields a combination of desired characteristics including simplified control structure, small ripple torque, high speed accuracy, wide operating speed range, and fast dynamic response. Experimental results confirm excellent characteristics of the motor.展开更多
Verbs of creation in English and Chinese demonstrate asymmetries in its projection to double-object construction. But underling the projection process there is a uniform operation mechanism, namely that the configurat...Verbs of creation in English and Chinese demonstrate asymmetries in its projection to double-object construction. But underling the projection process there is a uniform operation mechanism, namely that the configuration is affected by the interaction between the Meaning Assignment Principle （MAP）, the Distance Principle of Iconicity （DPI） and the Lexical Feature Constraints （LFC）, among which MAP and DPI are inviolable due to its cross-linguistic universality. Once LFC is violated, there must be compensation on the part of DPI, otherwise, the verb of creation in question would be unacceptable to double-object construction.展开更多
A novel twin-rotor piston engine （TRPE） mechanism with high volumetric output and power density was introduced. This new engine comprises an energy conversion system and a differential velocity drive mechanism （DVD...A novel twin-rotor piston engine （TRPE） mechanism with high volumetric output and power density was introduced. This new engine comprises an energy conversion system and a differential velocity drive mechanism （DVDM）. Two special geared four-bar mechanisms, DVDM-1 and DVDM-2, were utilized and compared. Based on the closed loop vector method, a mathematical model for position, velocity, and acceleration of the two mechanisms was established. Numerical examples illustrate that the kinematic characteristics were presented. Expression of the displacement and compression ratio of the two engine mechanisms were derived and compared. It is concluded that both DVDM-1 and DVDM-2 adopted in the proposed TRPE with six vane pistons create thirty-six power strokes per revolution of the output shaft, and the summation of two angles covered by each rocker is always 2x/N as the output shaft rotates an angle of x/N. In DVDM-1, the span angle of a vane piston should be designed to be 10.2°, and the compression ratio should be equal to 10; in DVDM-2, the span angle of a vane piston should be designed to be 10.6°, and the compression ratio should be equal to 4.3.展开更多
We study the attack vulnerability of network with duplication-divergence mechanism. Numerical results have shown that the duplication-divergence network with larger retention probability a is more robust against targe...We study the attack vulnerability of network with duplication-divergence mechanism. Numerical results have shown that the duplication-divergence network with larger retention probability a is more robust against target attack relatively. Furthermore, duplication-divergence network is broken down more quickly than its counterpart BA network under target attack. Such result is consistent with the fact of WWW and Internet networks under target attack. So duplication-divergence model is a more realistic one for us to investigate the characteristics of the world wide web in future. We also observe that the exponent γ of degree distribution and average degree are important parameters of networks, reflecting the performance of networks under target attack. Our results are helpful to the research on the security of network.展开更多
The interfering kinetics of the coherent synchronous reactions of hydrogen peroxide decomposition and the oxidation of pyridine derivatives have been studied experimentally. The regions of the selective oxidation of t...The interfering kinetics of the coherent synchronous reactions of hydrogen peroxide decomposition and the oxidation of pyridine derivatives have been studied experimentally. The regions of the selective oxidation of the pyridine derivatives have been found, and the optimal conditions for the production of4-vynilpyridine, 4-vynilpyridine N-monoxide, 2, 2-dipyridyl, and pyridine have been determined. The most probable synchronization mechanism is suggested for hydrogen peroxide decomposition and the free-radical chain oxidation of pyridine derivatives. The HO2 -radical plays the key role in this mechanism. The activation energies are calculated for the elementary steps of 4-ethylpyridine dehydrogenation.展开更多
The power of the toroidal field （TF） coil in HL-2A is supplied with two 80 MVA motor generators （MGs） together through a diode rectifier. The TF system is designed to obtain the parameters as follows： the highest...The power of the toroidal field （TF） coil in HL-2A is supplied with two 80 MVA motor generators （MGs） together through a diode rectifier. The TF system is designed to obtain the parameters as follows： the highest toroidal filed of 2.8 T, the biggest coil current of 45 kA, the fiat top time of 3-5 s. So the released energy of each MG set for one pulse discharge mast be more than 500 MJ.展开更多
This paper presents a control algorithm for push recovery, which particularly focuses on the hip strategy when an external disturbance is applied on the body of a standing under-actuated biped. By analyzing a simplifi...This paper presents a control algorithm for push recovery, which particularly focuses on the hip strategy when an external disturbance is applied on the body of a standing under-actuated biped. By analyzing a simplified dynamic model of a bipedal robot in the stance phase, it is found that horizontal stability can be maintained with a suitably controlled torque applied at the hip. However, errors in the angle or angular velocity of body posture may appear, due to the dynamic coupling of the transla- tional and rotational motions. To solve this problem, different hip strategies are discussed for two cases when （1） external dis- turbance is applied on the center of mass （CoM） and （2） external torque is acting around the CoM, and a universal hip strategy is derived for most disturbances. Moreover, three torque primitives for the hip, depending on the type of disturbance, are designed to achieve translational and rotational balance recovery simultaneously. Compared with closed-loop control, the advantage of the open-loop methods of torque primitives lies in rapid response and reasonable performance. Finally, simulation studies of the push recovery of a bipedal robot are presented to demonstrate the effectiveness of the proposed methods.展开更多
文摘A new type of brushless DC motor has been developed by using a square wave rare earth permanent magnet synchronous motor with its double loop control circuit. The double loop control scheme of the drive system yields a combination of desired characteristics including simplified control structure, small ripple torque, high speed accuracy, wide operating speed range, and fast dynamic response. Experimental results confirm excellent characteristics of the motor.
文摘Verbs of creation in English and Chinese demonstrate asymmetries in its projection to double-object construction. But underling the projection process there is a uniform operation mechanism, namely that the configuration is affected by the interaction between the Meaning Assignment Principle （MAP）, the Distance Principle of Iconicity （DPI） and the Lexical Feature Constraints （LFC）, among which MAP and DPI are inviolable due to its cross-linguistic universality. Once LFC is violated, there must be compensation on the part of DPI, otherwise, the verb of creation in question would be unacceptable to double-object construction.
基金Project(7131109) supported the by National Defense Pre-research Foundation of ChinaProject(50975278) supported by National the Natural Science Foundation of China
文摘A novel twin-rotor piston engine （TRPE） mechanism with high volumetric output and power density was introduced. This new engine comprises an energy conversion system and a differential velocity drive mechanism （DVDM）. Two special geared four-bar mechanisms, DVDM-1 and DVDM-2, were utilized and compared. Based on the closed loop vector method, a mathematical model for position, velocity, and acceleration of the two mechanisms was established. Numerical examples illustrate that the kinematic characteristics were presented. Expression of the displacement and compression ratio of the two engine mechanisms were derived and compared. It is concluded that both DVDM-1 and DVDM-2 adopted in the proposed TRPE with six vane pistons create thirty-six power strokes per revolution of the output shaft, and the summation of two angles covered by each rocker is always 2x/N as the output shaft rotates an angle of x/N. In DVDM-1, the span angle of a vane piston should be designed to be 10.2°, and the compression ratio should be equal to 10; in DVDM-2, the span angle of a vane piston should be designed to be 10.6°, and the compression ratio should be equal to 4.3.
基金The project supported by National Natural Science Foundation of China under Grant No. 10375022Acknowledgment We thank Prof. Tang Yi for helpful discussions.
文摘We study the attack vulnerability of network with duplication-divergence mechanism. Numerical results have shown that the duplication-divergence network with larger retention probability a is more robust against target attack relatively. Furthermore, duplication-divergence network is broken down more quickly than its counterpart BA network under target attack. Such result is consistent with the fact of WWW and Internet networks under target attack. So duplication-divergence model is a more realistic one for us to investigate the characteristics of the world wide web in future. We also observe that the exponent γ of degree distribution and average degree are important parameters of networks, reflecting the performance of networks under target attack. Our results are helpful to the research on the security of network.
文摘The interfering kinetics of the coherent synchronous reactions of hydrogen peroxide decomposition and the oxidation of pyridine derivatives have been studied experimentally. The regions of the selective oxidation of the pyridine derivatives have been found, and the optimal conditions for the production of4-vynilpyridine, 4-vynilpyridine N-monoxide, 2, 2-dipyridyl, and pyridine have been determined. The most probable synchronization mechanism is suggested for hydrogen peroxide decomposition and the free-radical chain oxidation of pyridine derivatives. The HO2 -radical plays the key role in this mechanism. The activation energies are calculated for the elementary steps of 4-ethylpyridine dehydrogenation.
文摘The power of the toroidal field （TF） coil in HL-2A is supplied with two 80 MVA motor generators （MGs） together through a diode rectifier. The TF system is designed to obtain the parameters as follows： the highest toroidal filed of 2.8 T, the biggest coil current of 45 kA, the fiat top time of 3-5 s. So the released energy of each MG set for one pulse discharge mast be more than 500 MJ.
基金Project supported by the National Natural Science Foundation of China （Nos. 51405430 and 61473258） and the National High-Tech R＆D Program （863） of China （No. 2012AA041703）
文摘This paper presents a control algorithm for push recovery, which particularly focuses on the hip strategy when an external disturbance is applied on the body of a standing under-actuated biped. By analyzing a simplified dynamic model of a bipedal robot in the stance phase, it is found that horizontal stability can be maintained with a suitably controlled torque applied at the hip. However, errors in the angle or angular velocity of body posture may appear, due to the dynamic coupling of the transla- tional and rotational motions. To solve this problem, different hip strategies are discussed for two cases when （1） external dis- turbance is applied on the center of mass （CoM） and （2） external torque is acting around the CoM, and a universal hip strategy is derived for most disturbances. Moreover, three torque primitives for the hip, depending on the type of disturbance, are designed to achieve translational and rotational balance recovery simultaneously. Compared with closed-loop control, the advantage of the open-loop methods of torque primitives lies in rapid response and reasonable performance. Finally, simulation studies of the push recovery of a bipedal robot are presented to demonstrate the effectiveness of the proposed methods.
