This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained ...This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained SiGe p＋ layer to overcome the drawbacks of existing Si switching power diode. The SJ SiGe diode can achieve low specific on-resistance, high breakdown voltages and fast switching speed. The results indicate that the forward voltage drop of SJ SiGe diode is much lower than that of conventional Si power diode when the operating current densities do not exceed 1000 A/cm^2, which is very good for getting lower operating loss. The forward voltage drop of the Si diode is 0.66V whereas that of the SJ SiGe diode is only 0.52V voltages are 203 V for the former and 235 V for the latter. at operating current density of 10A/cm^2. The breakdown Compared with the conventional Si power diode, the reverse recovery time of SJ SiGe diode with 20 per cent Ge content is shortened by above a half and the peak reverse current is reduced by over 15%. The SJ SiGe diode can remarkably improve the characteristics of power diode by combining the merits of both SJ structure and SiGe material.展开更多
Global synchronization of a class of directed dynamical networks with switching topologies is investigated.It is found that if there is a directed spanning tree in the fixed time-average of network topology and the ti...Global synchronization of a class of directed dynamical networks with switching topologies is investigated.It is found that if there is a directed spanning tree in the fixed time-average of network topology and the time-averageis achieved sufficiently fast,then the network will reach global synchronization for sufficiently large coupling strength.展开更多
Diffractive optical elements attract a considerable amount of attention, mainly due to their potential applications in imaging coding, optical sensing, etc. Application of ferroelectric liquid crystals(FLCs) with phot...Diffractive optical elements attract a considerable amount of attention, mainly due to their potential applications in imaging coding, optical sensing, etc. Application of ferroelectric liquid crystals(FLCs) with photoalignment technology in diffractive optical elements results in a high efficiency and a fast response time. In this study we demonstrate a circular Dammann grating(CDG) with a diffraction efficiency of 84.5%. The achieved response time of 64 μs is approximately two orders of magnitude faster than the existing response time of nematic liquid crystal devices. By applying a low electric field(V = 6 V) to the FLC CDG, it is switched between the eight-order diffractive state and the transmissive diffraction-free state.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
Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3-...Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3- bis（4-decyloxyphenyl）-5,8-bis（3,4-dimethoxylthiophen-2-yl）quinoxaline] （P1） and poly[2,3-bis（4-decyloxyphenyl）-5,8- bis（2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl）quinoxaline] （P2）, are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance （NMR）, mass spectrometry （MS）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, ultraviolet-visible absorption spectrometry （UV-Vis） and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42% （595 nm）, 30% （839 nm） and 69% （1500 nm） transmittance changes （A7%）, while P2 exhibited 32% （740 nm）, 71% （2000 nm） at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.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
This paper addresses the problems of stability and stabilisation of Markovian jump systems(MJSs)with fast switching.First,a novel model by applying an averaging approach to the fastswitching is proposed.Then,a new met...This paper addresses the problems of stability and stabilisation of Markovian jump systems(MJSs)with fast switching.First,a novel model by applying an averaging approach to the fastswitching is proposed.Then,a new method for constructing an auxiliary system is given to makethe stability analysis.It is proved that the stability of the originally fast switching MJS couldbe guaranteed by an MJS with an average switching,if the fast switching achieves its averageapproximation sufficiently fast.Based on the proposed results,some extensions about generally stabilising controllers are considered,where the fault-tolerant situation is involved too.All the conditions are presented in terms of LMIs.Finally,two numerical examples are used todemonstrate the effectiveness and superiority of the method.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 50477012)the Doctoral Program Foundation of Institutes of Higher Education of China (Grant No 20050700006)the Special Scientific Research Program of the Education Bureau of Shaanxi Province,China (Grant No 05JK268)
文摘This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained SiGe p＋ layer to overcome the drawbacks of existing Si switching power diode. The SJ SiGe diode can achieve low specific on-resistance, high breakdown voltages and fast switching speed. The results indicate that the forward voltage drop of SJ SiGe diode is much lower than that of conventional Si power diode when the operating current densities do not exceed 1000 A/cm^2, which is very good for getting lower operating loss. The forward voltage drop of the Si diode is 0.66V whereas that of the SJ SiGe diode is only 0.52V voltages are 203 V for the former and 235 V for the latter. at operating current density of 10A/cm^2. The breakdown Compared with the conventional Si power diode, the reverse recovery time of SJ SiGe diode with 20 per cent Ge content is shortened by above a half and the peak reverse current is reduced by over 15%. The SJ SiGe diode can remarkably improve the characteristics of power diode by combining the merits of both SJ structure and SiGe material.
基金Supported by the Natural Science Foundation of Hohai University under Grant No.2008429211
文摘Global synchronization of a class of directed dynamical networks with switching topologies is investigated.It is found that if there is a directed spanning tree in the fixed time-average of network topology and the time-averageis achieved sufficiently fast,then the network will reach global synchronization for sufficiently large coupling strength.
基金supported by the National Natural Science Foundation of China (Nos. 61405009,61875004,61705067)the Defense Industrial Technology Development Program (No. JCKY2019601C101)+1 种基金the Shanghai Pujiang Program (16PJ1402200)supported by the Russian Science Foundation (No. 20-19-00201)。
文摘Diffractive optical elements attract a considerable amount of attention, mainly due to their potential applications in imaging coding, optical sensing, etc. Application of ferroelectric liquid crystals(FLCs) with photoalignment technology in diffractive optical elements results in a high efficiency and a fast response time. In this study we demonstrate a circular Dammann grating(CDG) with a diffraction efficiency of 84.5%. The achieved response time of 64 μs is approximately two orders of magnitude faster than the existing response time of nematic liquid crystal devices. By applying a low electric field(V = 6 V) to the FLC CDG, it is switched between the eight-order diffractive state and the transmissive diffraction-free state.
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.
基金financially supported by the National Natural Science Foundation of China(Nos.51473074 and 31400044)the General and Special Program of the Postdoctoral Science Foundation China(Nos.2013M530397 and 2014T70861)+1 种基金the Postgraduate Innovation Project of China University of Petroleum(East China)(No.YCX2015022)the Fundamental Research Funds for the Central Universities(No.15CX06049A)
文摘Two novel decyloxyphenylquinoxaline-based donor-acceptor （D-A） electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3- bis（4-decyloxyphenyl）-5,8-bis（3,4-dimethoxylthiophen-2-yl）quinoxaline] （P1） and poly[2,3-bis（4-decyloxyphenyl）-5,8- bis（2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl）quinoxaline] （P2）, are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance （NMR）, mass spectrometry （MS）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, ultraviolet-visible absorption spectrometry （UV-Vis） and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42% （595 nm）, 30% （839 nm） and 69% （1500 nm） transmittance changes （A7%）, while P2 exhibited 32% （740 nm）, 71% （2000 nm） at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.
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supported by the Open Project of Key Field Alliance of Liaoning Province[grant number 2022-KF-11-03].
文摘This paper addresses the problems of stability and stabilisation of Markovian jump systems(MJSs)with fast switching.First,a novel model by applying an averaging approach to the fastswitching is proposed.Then,a new method for constructing an auxiliary system is given to makethe stability analysis.It is proved that the stability of the originally fast switching MJS couldbe guaranteed by an MJS with an average switching,if the fast switching achieves its averageapproximation sufficiently fast.Based on the proposed results,some extensions about generally stabilising controllers are considered,where the fault-tolerant situation is involved too.All the conditions are presented in terms of LMIs.Finally,two numerical examples are used todemonstrate the effectiveness and superiority of the method.
