Soft-switching techniques are attractive to unity-power-factor AC/DC converter in the view of the size reduction and EMI suppression. A soft-switched boost PFC converter has been studied based on its topology analysis...Soft-switching techniques are attractive to unity-power-factor AC/DC converter in the view of the size reduction and EMI suppression. A soft-switched boost PFC converter has been studied based on its topology analysis, PSIM simulation and circuit experiment. A special limitation of soft-switching techniques has been found in their AC/DC applications.展开更多
Silver nanoparticles were synthesized using an aqueous extract of cinnamon berks (cinnamon cassia) as a reducer and stabilizer. The synthesized silver nanoparticles were characterized using UV-Vis spectrometry and Tra...Silver nanoparticles were synthesized using an aqueous extract of cinnamon berks (cinnamon cassia) as a reducer and stabilizer. The synthesized silver nanoparticles were characterized using UV-Vis spectrometry and Transmission Electron Microscopy (TEM), which revealed the nano nature of the particles. Nonlinear absorption and nonlinear refraction were measured using a Z-scan technique at different wavelengths with CW lasers. The third order nonlinear susceptibility was found to be between (1.5 to 22) ×10-14 m2/V2. The nonlinear property of the synthesized silver nanoparticles was used to demonstrate optical limiting and all-optical switching. An optical limiting threshold was found to be 0.1 mW at 632.8 nm.展开更多
This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connecte...This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.展开更多
A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch...A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.展开更多
A switched system approach is proposed to model networked control systems （NCSs） with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient condit...A switched system approach is proposed to model networked control systems （NCSs） with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient conditions are presented on the stabilization of NCSs. Stabilizing state/output feedback controllers can be constructed by using the feasible solutions of some linear matrix inequalities （LMIs）. The merit of our proposed approach is that the behavior of the NCSs can be studied by considering switched system without augmenting the system. A simulation example is worked out to illustrate the effectiveness of the proposed approach.展开更多
The(001) oriented BiFeO_3 thin film was deposited on the Nb: SrTiO_3 substrate by radio frequency magnetron sputtering technology, and the bipolar resistive switching effect was observed in the BiFeO_3/Nb: SrTiO_3 het...The(001) oriented BiFeO_3 thin film was deposited on the Nb: SrTiO_3 substrate by radio frequency magnetron sputtering technology, and the bipolar resistive switching effect was observed in the BiFeO_3/Nb: SrTiO_3 heterostructure. The results showed that the ratio between the high resistance and low resistance was more than two orders at a reading pulse of-0.5 V and it exhibited excellent retention over 3600 s. The current density-voltage characteristic was dominated by the space-charge-limited conduction. The resistive switching effect of the structure was attributed to the trapping/detrapping of the charge carriers.展开更多
基金Sponsored by the Scientific Research Foundaltion fbr the Returned Overseas Chinese Scholars,Ministry of Education
文摘Soft-switching techniques are attractive to unity-power-factor AC/DC converter in the view of the size reduction and EMI suppression. A soft-switched boost PFC converter has been studied based on its topology analysis, PSIM simulation and circuit experiment. A special limitation of soft-switching techniques has been found in their AC/DC applications.
文摘Silver nanoparticles were synthesized using an aqueous extract of cinnamon berks (cinnamon cassia) as a reducer and stabilizer. The synthesized silver nanoparticles were characterized using UV-Vis spectrometry and Transmission Electron Microscopy (TEM), which revealed the nano nature of the particles. Nonlinear absorption and nonlinear refraction were measured using a Z-scan technique at different wavelengths with CW lasers. The third order nonlinear susceptibility was found to be between (1.5 to 22) ×10-14 m2/V2. The nonlinear property of the synthesized silver nanoparticles was used to demonstrate optical limiting and all-optical switching. An optical limiting threshold was found to be 0.1 mW at 632.8 nm.
文摘This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.
文摘A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.
基金This work is supported by the National Natural Science Foundation of China (No. 60528007, 10372002, 60274001, 60304003), the National KeyBasic Research and Development Program (No. 2002CB312200).
文摘A switched system approach is proposed to model networked control systems （NCSs） with communication constraints. This enables us to apply the rich theory of switched systems to analyzing such NCSs. Sufficient conditions are presented on the stabilization of NCSs. Stabilizing state/output feedback controllers can be constructed by using the feasible solutions of some linear matrix inequalities （LMIs）. The merit of our proposed approach is that the behavior of the NCSs can be studied by considering switched system without augmenting the system. A simulation example is worked out to illustrate the effectiveness of the proposed approach.
基金Funded by the National Natural Science Foundation of China(Nos.61201046 and 61306057)the Beijing Natural Science Foundation of China(Nos.4162013,2132023 and 4164082)+2 种基金the Beijing Postdoctoral Research Foundation(No.2015ZZ-33)the Scientific Research Project of Beijing Educational Committee(No.KM201610005005)the Scientific Research Foundation for Returned Overseas Chinese Scholars,State Education Ministry
文摘The(001) oriented BiFeO_3 thin film was deposited on the Nb: SrTiO_3 substrate by radio frequency magnetron sputtering technology, and the bipolar resistive switching effect was observed in the BiFeO_3/Nb: SrTiO_3 heterostructure. The results showed that the ratio between the high resistance and low resistance was more than two orders at a reading pulse of-0.5 V and it exhibited excellent retention over 3600 s. The current density-voltage characteristic was dominated by the space-charge-limited conduction. The resistive switching effect of the structure was attributed to the trapping/detrapping of the charge carriers.
