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
ABSTRACTThis 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. Th...ABSTRACTThis 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
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
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
软件定义广域网(Software Defined Wide Area Network,SD-WAN)作为被应用于广域网连接的新型网络技术,使用混合链路为广域网流量提供多条Overlay转发路径,配合智能应用选路等技术为网络流量提供最优路径动态选择的能力。提出了一种基于...软件定义广域网(Software Defined Wide Area Network,SD-WAN)作为被应用于广域网连接的新型网络技术,使用混合链路为广域网流量提供多条Overlay转发路径,配合智能应用选路等技术为网络流量提供最优路径动态选择的能力。提出了一种基于混合链路多Overlay隧道实现网络规模解耦下快速路由切换的新型设计,在广域网链路中断后提供路由收敛时间确定性上界保证,给出关键的数据结构及工作流程,对相关工程实施具备较好的指导作用。展开更多
Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum...Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum is an eco-friendly technology compared to switching in SF 6 gas,which is the strongest greenhouse gas according to the Kyoto Protocol.Vacuum,an eco-friendly natural medium,is promising for reducing the usage of SF 6 gas in current switching in transmission voltage.Second,switching in vacuum achieves faster current interruption than existing alternating current(AC)switching technolo-gies.A vacuum circuit breaker(VCB)that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption,which can interrupt a short-circuit current in the first half-cycle of a fault current,compared to the more common three cycles for existing current switching technologies.This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults,especially for ultra-and extra-high-voltage power transmission lines.Third,based on fast vacuum switching technology,various brilliant applications emerge,which are benefiting the power systems.They include the applications in the fields of direct current(DC)circuit breakers(CBs),fault current lim-iting,power quality improvement,generator CBs,and so forth.Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times.With this controlled switching,vacuum switching technology may change the“gene”of power systems,by which power switching transients will become smoother.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 Open Project of Key Field Alliance of Liaoning Province[grant number 2022-KF-11-03].
文摘ABSTRACTThis 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.
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.
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.
文摘软件定义广域网(Software Defined Wide Area Network,SD-WAN)作为被应用于广域网连接的新型网络技术,使用混合链路为广域网流量提供多条Overlay转发路径,配合智能应用选路等技术为网络流量提供最优路径动态选择的能力。提出了一种基于混合链路多Overlay隧道实现网络规模解耦下快速路由切换的新型设计,在广域网链路中断后提供路由收敛时间确定性上界保证,给出关键的数据结构及工作流程,对相关工程实施具备较好的指导作用。
基金supported in part by the National Natural Science Foundation of China (51937009 and 51877166)the Key Research and Development Program of Shaanxi Province (2019ZDLGY18-04)
文摘Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum is an eco-friendly technology compared to switching in SF 6 gas,which is the strongest greenhouse gas according to the Kyoto Protocol.Vacuum,an eco-friendly natural medium,is promising for reducing the usage of SF 6 gas in current switching in transmission voltage.Second,switching in vacuum achieves faster current interruption than existing alternating current(AC)switching technolo-gies.A vacuum circuit breaker(VCB)that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption,which can interrupt a short-circuit current in the first half-cycle of a fault current,compared to the more common three cycles for existing current switching technologies.This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults,especially for ultra-and extra-high-voltage power transmission lines.Third,based on fast vacuum switching technology,various brilliant applications emerge,which are benefiting the power systems.They include the applications in the fields of direct current(DC)circuit breakers(CBs),fault current lim-iting,power quality improvement,generator CBs,and so forth.Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times.With this controlled switching,vacuum switching technology may change the“gene”of power systems,by which power switching transients will become smoother.
