This work addresses the saturation influence of control voltage on the occurring of self-excited vibration of maglev vehicle-bridge interaction system, which greatly degrades the stability of the levitation control, d...This work addresses the saturation influence of control voltage on the occurring of self-excited vibration of maglev vehicle-bridge interaction system, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the interaction model of vehicle-bridge system is developed. Based on the interaction model, the relationship between the control voltage and vibration frequency is solved. Then, the variation of the effective direct component and fundamental harmonic are discussed. Furthermore, from the perspective of energy transmission between the levitation system and bridge, the principle underlying the self-excited vibration is explored, and the influence on the stability is discussed. Finally, in terms of the variation of the characteristic roots, the influence is analyzed further and some conclusions are obtained. This study provides a theoretical guidance for mastering the self-excited vibration problems.展开更多
An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and te...An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature com-pensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement tem-perature compensation for modulation current,a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region,and alternates the amplifier feedback loop(closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors,the IC can provide modu-lation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps,with the output optical power being nearly constant,and the variation of extinction ratio being lower than 0.7 dB.展开更多
All-optical coherent control of optical bistability （013） and optical multistability （OM） in the 4.8 nm ZnSe single-quantum well based on excitons and biexciton transitions is investigated. By applying a pair of p...All-optical coherent control of optical bistability （013） and optical multistability （OM） in the 4.8 nm ZnSe single-quantum well based on excitons and biexciton transitions is investigated. By applying a pair of phase-locked laser pulses all-optical coherent control can be obtained. Theoretical analysis with density matrix and Maxwell equations then yield the optical bistability ~nd optical multistability. It is shown that by controlling the coherent and incoherent processes, the intensity threshold of OB and OM can be modified. Also, it is found that the switching between OB and OM or vice versa can be occurred for some controllable parameters.展开更多
基金Projects(11302252,11202230)supported by the National Natural Science Foundation of China
文摘This work addresses the saturation influence of control voltage on the occurring of self-excited vibration of maglev vehicle-bridge interaction system, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the interaction model of vehicle-bridge system is developed. Based on the interaction model, the relationship between the control voltage and vibration frequency is solved. Then, the variation of the effective direct component and fundamental harmonic are discussed. Furthermore, from the perspective of energy transmission between the levitation system and bridge, the principle underlying the self-excited vibration is explored, and the influence on the stability is discussed. Finally, in terms of the variation of the characteristic roots, the influence is analyzed further and some conclusions are obtained. This study provides a theoretical guidance for mastering the self-excited vibration problems.
基金Project (No. 2006AA01Z226) supported by the Hi-Tech Researchand Development Program (863) of China
文摘An integrated laser diode driver(LDD) driving an edge-emitting laser diode was designed and fabricated by 0.35 μm BiCMOS technology. This paper proposes a scheme which combines the automatic power control loop and temperature com-pensation for modulation current in order to maintain constant extinction ratio and average optical power. To implement tem-perature compensation for modulation current,a novel circuit which generates a PTAT current by using the injecting base current of a bipolar transistor in saturation region,and alternates the amplifier feedback loop(closed or not) to control the state of the current path is presented. Simulation results showed that programmed by choice of external resistors,the IC can provide modu-lation current from 5 mA to 85 mA with temperature compensation adjustments and independent bias current from 4 mA to 100 mA. Optical test results showed that clear eye-diagrams can be obtained at 155 Mbps,with the output optical power being nearly constant,and the variation of extinction ratio being lower than 0.7 dB.
文摘All-optical coherent control of optical bistability （013） and optical multistability （OM） in the 4.8 nm ZnSe single-quantum well based on excitons and biexciton transitions is investigated. By applying a pair of phase-locked laser pulses all-optical coherent control can be obtained. Theoretical analysis with density matrix and Maxwell equations then yield the optical bistability ~nd optical multistability. It is shown that by controlling the coherent and incoherent processes, the intensity threshold of OB and OM can be modified. Also, it is found that the switching between OB and OM or vice versa can be occurred for some controllable parameters.
