The linear and non-linear math models of the switched reluctance generator (SRG) in generator mode were established in this work. The phase current and energy conversion process during generator operation were simulat...The linear and non-linear math models of the switched reluctance generator (SRG) in generator mode were established in this work. The phase current and energy conversion process during generator operation were simulated by the linear math model. The non-linear math model was used to analyze the characteristics of the SRG operation in self-excitation mode and in separately-excitation mode. Some important findings on how the SRG is operated and controlled were obtained in this study, which provides theoretical basis for further design and experimental study.展开更多
Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy we...Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology and structure of the multilayered nanowire arrays. Vibrating sample magnetometer and physical property measurement system were used to measure their magnetic and giant magnetoresistance （GMR） properties. The effect of sub-layer thickness on the magnetic and GMR properties was investigated. The results indicate that magnetic properties of electmdeposited nanowires are not affected obviously by Cu layer thickness, while magnetic layers （Ni-Fe and Co layers） have significant influence. In addition, GMR ratio presents an oscillatory behavior as Cu layer thickness changes. The magnetic and GMR properties of the multilayered nanowire arrays are optimum at room temperature for the material structure of Ni-Fe （25 nm）/Cu （15 nm）/Co （25 nm）/Cu （15 nm） with 30 deposition cycles.展开更多
A new type of linear rotary magnetorheological damper (MRD) is proposed, which consists of a cylinder-type MRD and a screw mechanism to transform a linear motion into revolving motion. It is found that the structure p...A new type of linear rotary magnetorheological damper (MRD) is proposed, which consists of a cylinder-type MRD and a screw mechanism to transform a linear motion into revolving motion. It is found that the structure parameters of MRD have complex relationship with the force of the damper, especially the lead angle, width and radius of the inner rotor. The analyses and simulation calculation of the static magnetic field give some usable data, and experiments of the damping component indicate that the proposed methods is feasible for developing linear rotary MRD.展开更多
The proof system, based on resolution method, has become quite popular in automatic theorem proving, because this method is simple to implement. At present many kinds of extensions for resolution method are known： Re...The proof system, based on resolution method, has become quite popular in automatic theorem proving, because this method is simple to implement. At present many kinds of extensions for resolution method are known： Resolution with restricted number of variables in disjuncts, resolution over Linear Equations, Cutting planes, etc. For Classical, Intuitionistic and Minimal （Johansson＇s） propositional logics, the authors introduce the family of resolution systems with full substitution rule （SRC, SRI and SRM） and with e-restricted substitution rule （SeRC, SeRf and SeRM）, where the number of substituted formula connectives is bounded by . The authors show that for each of mentioned logic the SR-type system （in tree form） is polynomially equivalent to Frege systems by size, but for every ~＇ 〉 0, Se＋lR-type has exponential speed-up over the SeR-type （in tree form）.展开更多
In this paper, a new control method for synchronous motor with excitation and damper windings is presented. It is based on one type of nonlinear control; feedback linearization control. To make a realization in the se...In this paper, a new control method for synchronous motor with excitation and damper windings is presented. It is based on one type of nonlinear control; feedback linearization control. To make a realization in the sense of electric drive, symmetricM space vector PWM （pulse width modulation） is applied. Estimation of damper winding currents via Lyapunov function for the whole estimated system is done. The aim of control is to make tracking system for rotor speed and square of stator flux. Simulation of motor starting to predefined operating points is done, and also maintaining these points during step change of load torque is obtained. Simulations give good results.展开更多
In this study, a visualization-based experiment was performed to measure the motion of the nanowire under a magnetic field. A simulation method based on a multiple reference flame model （MRF model） was used to calcu...In this study, a visualization-based experiment was performed to measure the motion of the nanowire under a magnetic field. A simulation method based on a multiple reference flame model （MRF model） was used to calcu- late fluid torque. Here, it was validated with the experimental data and theoretical results. Fluid torque of steady rotated nanowire was simulated and compared using experiment and theoretical models. The unsteady rotated condition was studied using transient simulation to compare with theory and the results showed that the accelera- tion of nanowire did not affect the flow field, indicating that the theoretical models based on the steady condition were still valid. The influence of solid walls on nanowire rotation was also studied here. The results showed that if the nanowire was placed close to the wall, the viscous force of wall would increase the velocity gradient around the nanowire, causing higher torque predictions. The fluid torque decreased quickly when the vertical distance between nanowire and wall exceeded 5 times the diameter of the wire.展开更多
文摘The linear and non-linear math models of the switched reluctance generator (SRG) in generator mode were established in this work. The phase current and energy conversion process during generator operation were simulated by the linear math model. The non-linear math model was used to analyze the characteristics of the SRG operation in self-excitation mode and in separately-excitation mode. Some important findings on how the SRG is operated and controlled were obtained in this study, which provides theoretical basis for further design and experimental study.
基金Supported by the Natural Science Foundation of Tianjin,China(08JCZDJC17400)
文摘Ni-Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology and structure of the multilayered nanowire arrays. Vibrating sample magnetometer and physical property measurement system were used to measure their magnetic and giant magnetoresistance （GMR） properties. The effect of sub-layer thickness on the magnetic and GMR properties was investigated. The results indicate that magnetic properties of electmdeposited nanowires are not affected obviously by Cu layer thickness, while magnetic layers （Ni-Fe and Co layers） have significant influence. In addition, GMR ratio presents an oscillatory behavior as Cu layer thickness changes. The magnetic and GMR properties of the multilayered nanowire arrays are optimum at room temperature for the material structure of Ni-Fe （25 nm）/Cu （15 nm）/Co （25 nm）/Cu （15 nm） with 30 deposition cycles.
文摘A new type of linear rotary magnetorheological damper (MRD) is proposed, which consists of a cylinder-type MRD and a screw mechanism to transform a linear motion into revolving motion. It is found that the structure parameters of MRD have complex relationship with the force of the damper, especially the lead angle, width and radius of the inner rotor. The analyses and simulation calculation of the static magnetic field give some usable data, and experiments of the damping component indicate that the proposed methods is feasible for developing linear rotary MRD.
文摘The proof system, based on resolution method, has become quite popular in automatic theorem proving, because this method is simple to implement. At present many kinds of extensions for resolution method are known： Resolution with restricted number of variables in disjuncts, resolution over Linear Equations, Cutting planes, etc. For Classical, Intuitionistic and Minimal （Johansson＇s） propositional logics, the authors introduce the family of resolution systems with full substitution rule （SRC, SRI and SRM） and with e-restricted substitution rule （SeRC, SeRf and SeRM）, where the number of substituted formula connectives is bounded by . The authors show that for each of mentioned logic the SR-type system （in tree form） is polynomially equivalent to Frege systems by size, but for every ~＇ 〉 0, Se＋lR-type has exponential speed-up over the SeR-type （in tree form）.
文摘In this paper, a new control method for synchronous motor with excitation and damper windings is presented. It is based on one type of nonlinear control; feedback linearization control. To make a realization in the sense of electric drive, symmetricM space vector PWM （pulse width modulation） is applied. Estimation of damper winding currents via Lyapunov function for the whole estimated system is done. The aim of control is to make tracking system for rotor speed and square of stator flux. Simulation of motor starting to predefined operating points is done, and also maintaining these points during step change of load torque is obtained. Simulations give good results.
基金supported by the National Natural Science Foundation of China (Grant No. 50876006)the Fundamental Research Funds for the Central Universities (Grant No. 2011YJS053)
文摘In this study, a visualization-based experiment was performed to measure the motion of the nanowire under a magnetic field. A simulation method based on a multiple reference flame model （MRF model） was used to calcu- late fluid torque. Here, it was validated with the experimental data and theoretical results. Fluid torque of steady rotated nanowire was simulated and compared using experiment and theoretical models. The unsteady rotated condition was studied using transient simulation to compare with theory and the results showed that the accelera- tion of nanowire did not affect the flow field, indicating that the theoretical models based on the steady condition were still valid. The influence of solid walls on nanowire rotation was also studied here. The results showed that if the nanowire was placed close to the wall, the viscous force of wall would increase the velocity gradient around the nanowire, causing higher torque predictions. The fluid torque decreased quickly when the vertical distance between nanowire and wall exceeded 5 times the diameter of the wire.
