A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sedimen...A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sediment concentration has an infinitely large value at the channel bottom and a zero value at the water surface. Based on this formula and the logarithmic ve- locity profile, a theoretical elementary function for the transport rate of a suspended load is developed. This equation improves the Einstein equation in which the unit-width suspended sediment discharge must be solved by numerical integration and a contra- diction between the lower limit of the integral and that of velocity distribution exists.展开更多
A new electromagnetic suspension model using a combination of high temperature superconductors (HTS) and copper conductors is proposed in this paper. A feasibility study showed that the magnets of our model can genera...A new electromagnetic suspension model using a combination of high temperature superconductors (HTS) and copper conductors is proposed in this paper. A feasibility study showed that the magnets of our model can generate the 250 kg vertical suspension force. Three dimensional FEM and Design Sensitivity Analysis using the levitation gap length and cross sectional dimensions of the HTS magnets as design parameters were conducted to obtain the optimal shape of the cross section and the configuration of the HTS magnet. It was found that the gap length when optimized HTS magnet was used was much larger than that when copper conductor magnet was used, while the HTS coil volume was minimum, and the perpendicular field along the outer surface of the HTS coil was less than 0.12 T.展开更多
In order to research the vibration law of electrostatic suspension systems in the vertical direction, the mathematical model as a nonlinear differential equation is established. A series of simulation is carried out. ...In order to research the vibration law of electrostatic suspension systems in the vertical direction, the mathematical model as a nonlinear differential equation is established. A series of simulation is carried out. The results show that the solution of the differential equation is a periodic function. The amplitude becomes bigger with the original velocity increased. The period becomes smaller with the original velocity increasing. The numerical methods are presented to derive the amplitude and the frequency, and the results coincide with that of the simulation. The condition during which the simple harmonic vibration arises is pointed out. The expressions for the amplitude and the period of simple harmonic vibration are derived respectively, and the results are the same with that of the simulation. This study is helpful for researching the vibration characteristics of the electrostatic suspension system. The external disturb should be controlled to lower the amplitude and the frequency of the vibration.展开更多
基金Project (Nos. 50079025 and 40231017) supported by the National Natural Science Foundation of China
文摘A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sediment concentration has an infinitely large value at the channel bottom and a zero value at the water surface. Based on this formula and the logarithmic ve- locity profile, a theoretical elementary function for the transport rate of a suspended load is developed. This equation improves the Einstein equation in which the unit-width suspended sediment discharge must be solved by numerical integration and a contra- diction between the lower limit of the integral and that of velocity distribution exists.
基金Project (No. 50477030) supported by the National Natural Science Foundation of China
文摘A new electromagnetic suspension model using a combination of high temperature superconductors (HTS) and copper conductors is proposed in this paper. A feasibility study showed that the magnets of our model can generate the 250 kg vertical suspension force. Three dimensional FEM and Design Sensitivity Analysis using the levitation gap length and cross sectional dimensions of the HTS magnets as design parameters were conducted to obtain the optimal shape of the cross section and the configuration of the HTS magnet. It was found that the gap length when optimized HTS magnet was used was much larger than that when copper conductor magnet was used, while the HTS coil volume was minimum, and the perpendicular field along the outer surface of the HTS coil was less than 0.12 T.
基金This study is supported by the National Natural Science Foundation (No.50375113).
文摘In order to research the vibration law of electrostatic suspension systems in the vertical direction, the mathematical model as a nonlinear differential equation is established. A series of simulation is carried out. The results show that the solution of the differential equation is a periodic function. The amplitude becomes bigger with the original velocity increased. The period becomes smaller with the original velocity increasing. The numerical methods are presented to derive the amplitude and the frequency, and the results coincide with that of the simulation. The condition during which the simple harmonic vibration arises is pointed out. The expressions for the amplitude and the period of simple harmonic vibration are derived respectively, and the results are the same with that of the simulation. This study is helpful for researching the vibration characteristics of the electrostatic suspension system. The external disturb should be controlled to lower the amplitude and the frequency of the vibration.
