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
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
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
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
Zinc anode-based electrochromic devices(ZECDs)represent a new generation of multifunctional electrochromic(EC)platforms,offering cost-effectiveness and high roundtrip efficiency.However,their practical application rem...Zinc anode-based electrochromic devices(ZECDs)represent a new generation of multifunctional electrochromic(EC)platforms,offering cost-effectiveness and high roundtrip efficiency.However,their practical application remains limited due to the electric field inhomogeneity and the growth of Zn dendrites issues primarily caused by the use of opaque peripheral Zinc(Zn)foils.Herein,we rationally designed a transparent(T=71.4%@633 nm),durable and flexible Ag-PVDF(polyvinylidene difluoride)coated Zinc(AP@Zn)mesh electrode.The AP@Zn mesh promotes a homogeneous electric field and potential distribution within ZECDs,exhibits excellent corrosion resistance,and possesses a low activation energy(47.59 kJ mol^(-1)).Furthermore,it demonstrates broad compatibility with various EC electrodes.As a result,a 5 cm×5 cm Prussian blue(PB)//AP@Zn achieved fast switching times(t_(c)/tb 2.8 s/2.6 s),high coloration efficiency(157.44 cm^(2)C^(-1)),outstanding cycling stability(93.7%ΔT retention after 500 cycles),and integrated energy storage functionalities(32.89 mA h m^(-2)at 0.02 mA cm^(-2)).A large,scalable 10 cm×10 cm PB//AP@Zn device showed significant faster switching times(t_(c)/tb 6.6 s/5.4 s)compared to the PB//Zn foil counterpart(t_(c)/tb 15 s/11.4 s).Importantly,we also demonstrated devices based on Nb_(18)W_(16)O_(93)(NWO)//AP@Zn,which exhibited fast switching(t_(c)/tb 18.5 s/20 s)and high durability(77.7%ΔT retention after 1200 cycles),as well as potassium vanadate(KVO)//AP@Zn featuring multicolor capabilities.Stacked PB//AP@Zn//KVO electrochromic displays exhibited a six-color palette including olive green1,tawny,bronzing,olive green2,deep blue-green,cool grayish green.This work underscores the critical role of electrode design in advancing ZECDs towards multifunctional and flexible electronics.展开更多
Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a ...Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a long service life.The breaking mechanism significantly affects the current interruption capability of DCCBs.The operation of the repulsion mechanism,along with the morphology of the arc and its transformation within the interrupter chamber,collectively influence the breaking performance of the FMSs.This paper presents a comprehensive analysis of the FMSs,which serves as the pivotal component of controlled resonance combination circuit breakers(CRCBs).This study establishes a multi physics coupling simulation analysis method based on the equivalent circuit of repulsion mechanism discharge,combined with electromagnetic and solid mechanics fields.By constructing a full cycle magnetohydrodynamic particle arc(MHP)model and using a combined simulation of Finite Element joint model(FEJM),the evolution law of arc characteristics during the superimposed current interruption process was systematically explored.The focus was on analysing the physical process of the zero zone of the superimposed arc,the multi physics field coupling relationship of the arc,and the interaction mechanism with external characteristic parameters.Further combining with optimisation design methods,the effectiveness of the model was verified through experiments,FEJM provides comprehensive technical support for effectively reflecting the stress issues of core components during the breaking process of FMS and can provide accurate theoretical references for the optimisation design of mechanical motion components in FMS.It also accurately represents the arc extinguishing process during the breaking of FMS and provides a convenient method for the selection and design of circuit parameters for the entire circuit breaker.展开更多
Polymer-embedded liquid crystals(LCs)play a pivotal role in smart applications,enabling precise tunability over electrooptical properties.However,high energy consumption in conventional LC-polymeric systems limits the...Polymer-embedded liquid crystals(LCs)play a pivotal role in smart applications,enabling precise tunability over electrooptical properties.However,high energy consumption in conventional LC-polymeric systems limits their efficiency in sustainable and environmental protection technologies.Reducing driving voltage without compromising mechanical and electro-optical performance remains an unresolved challenge.Here,we demonstrate a polymer-confined ferroelectric nematic(N_(F))liquid crystal system,polymerized with mesogenic and non-mesogenic monomers under an electric field.The effective multidomain polymer structure exploits the intriguing properties of the NFLC and generates a highly scattered state with an excellent contrast ratio in the N_(F)phase.Electric field-controlled reorientation of directors leads to a transparent state at a very small voltage.The system demonstrates the advantages of a low driving voltage,sub-millisecond switching time with negligible hysteresis,and improved durability,promoting applications in energy-saving smart windows.This work reveals valuable insights into leveraging NFLCs and tailoring polymer networks to advance the performance of electro-optic devices.展开更多
An imidazolium-based ionic liquid(IL)modified triphenylamine derivative,namely 1-(4-((4-(diphenylamino)benzoyl)oxy)butyl)-3-methyl imidazole tetrafluoroborate(TPAC_(6)IL-BF_(4)),was designed and synthesized,and furthe...An imidazolium-based ionic liquid(IL)modified triphenylamine derivative,namely 1-(4-((4-(diphenylamino)benzoyl)oxy)butyl)-3-methyl imidazole tetrafluoroborate(TPAC_(6)IL-BF_(4)),was designed and synthesized,and further applied with 3,4-ethylene dioxythiophene(EDOT)to prepare conjugated copolymer P(EDOT:TPAC_(6)IL-BF_(4)) via electrochemical polymerization.The cyclic voltammetry curves show that the copolymer P(EDOT:TPAC_(6)IL-BF_(4))possesses two pairs of redox peaks,which should be ascribed to the redox behaviors of EDOT and triphenylamine.The ultraviolet-visible(UV-Vis)absorption spectrum of P(EDOT:TPAC_(6)IL-BF_(4))exhibits one maximum absorption peak at 580 nm and a small shoulder characteristic peak at 385 nm under neutral state which are assigned toπ-π^(*)conjugated structure of EDOT and triphenylamine.After being applied at the positive voltage,the copolymer color changes from dark blue to light blue,which is close to the color of poly(3,4-ethylenedioxythiophene)(PEDOT).Surprisingly,the copolymer P(EDOT:TPAC_(6)IL-BF_(4))shows shorter switching time of 0.37 s,0.30 s at 580 nm and 0.38 s,0.45 s at 1100 nm compared with PEDOT.It is more intriguing that the copolymer P(EDOT:TPAC_(6)IL-BF_(4))exhibits electrochromism even in free supporting electrolyte.The results confirm that the existence of imidazolium-based ionic liquid has an improvement on the ion diffusion properties and the switching time of conjugated polymer,which may provide a potential direction for the preparation of high-performance electrochromic materials.展开更多
A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side...A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side,and double trenches together with an N-type carrier storage(N-CS)layer at the cathode side,named DT-NPN LIGBT.The NPN structure not only acts as an electron barrier to eliminate the snapback effect in the on-state within a smaller cell pitch but also provides an extra electron extracting path during the turn-off stage to decrease the turnoff loss(E_(off)).The double cathode trenches and N-CS layer hinder the hole from being extracted by the cathode quickly.They then enhance carrier storing effect and lead to a reduced on-state voltage drop(V_(on)).The latch-up immunity is improved by the double cathode trenches.Hence,the DT-NPN LIGBT obtains a superior tradeoff between the V_(on)and E_(off).Additionally,the DT-NPN LIGBT exhibits an improved blocking capability and weak dependence of breakdown voltage(BV)on the P+anode doping concentration because the NPN structure suppresses triggering the PNP transistor.The proposed LIGBT reduces the E_(off)by 55%at the same V_(on),and improves the BV by 7.3%compared to the conventional LIGBT.展开更多
Titration of pesticides onto sorption sites can determine sorption capacities on soils. Previous studies have tracked the sorption capacities and detailed kinetics of the uptake of atrazine and its decomposition bypro...Titration of pesticides onto sorption sites can determine sorption capacities on soils. Previous studies have tracked the sorption capacities and detailed kinetics of the uptake of atrazine and its decomposition byproduct hydroxyatrazine on different soils, including measurements made using LC-MS/MS. These studies have now been extended to explore sorption-desorption equilibria for a mixture of pesticides from soil using LC-MS/MS. Desorption of sorbed pesticide residues has environmental regulatory implications for pesticide levels in runoff, or for longer term sequestration, partitioning, and transport. The uptake of pesticides by the soil at equilibrium was measured for a number of different concentrations, and sorption capacities were estimated. Pesticide-soil interaction studies were conducted by exposing standard stock solutions of pesticide mixtures to a characterized Nova Scotia soil. The mixture contained atrazine and dicamba. Initial aqueous mixture concentrations ranging from 5 × 10<sup>-9</sup> to 10<sup>-5</sup> M or greater were exposed to 25 mg aliquots of soil and allowed to reach equilibrium. The total uptake of each pesticide was measured indirectly, by measuring the concentration remaining in solution using an IONICS 3Q 120 triple quadrupole mass spectrometer. These sorption capacities have been supplemented by studies examining equilibrium recovery rates from soil aliquots with different initial uptakes. This gives insight into the fraction of easily recoverable (reversibly sorbed) pesticides on the soil. Proper quantification of equilibrium constants and kinetic rate coefficients using high performance LC-MS/MS facilitates the construction of accurate, predictive models. Predictive kinetic models can successfully mimic the experimental results for solution concentration, labile sorption, and intra-particle diffusion, and could be used to guide regulatory practices.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
A novel high performance carrier stored trench bipolar transistor （CSTBT） with a field- modified P-base region is proposed. Due to the p-pillars inserted into the drift region extending the P-base region to the bott...A novel high performance carrier stored trench bipolar transistor （CSTBT） with a field- modified P-base region is proposed. Due to the p-pillars inserted into the drift region extending the P-base region to the bottom of the trench gate, the electric field around the trench gate is modified, preventing the CSTBT from breakdown in advance caused by a concentration of the electric field at the edge of the trench gate. The p-pillars under the p-well forming the novel P-base region also provide extra paths for hole transportation. Thus, the switching time is also reduced. Simulation results have shown that the blocking voltage （BV） of the novel CSTBT is almost 430 V higher exhibiting avalanche breakdown properties compared with the conventional CSTBT. Moreover, the turn-off time of the novel structure is 0.3μs （17%） shorter than the conventional CSTBT with the same gate length.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.
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.
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the National Natural Science Foundation of China(5257021138,52202320)National Natural Science Foundation of China-China Academy of Engineering Physics“NSAF”Joint Fund(U2230101)+3 种基金the National Natural Science Fund for Excellent Young Scientists Fund(Overseas)Program(GG2090007003)Shandong Excellent Young Scientists Fund(Overseas)Program(2023HWYQ-060)the Fundamental Research Funds for the Central Universities(WK2490000002)the Joint Research Center for Multi-Energy Complementation and Conversion.
文摘Zinc anode-based electrochromic devices(ZECDs)represent a new generation of multifunctional electrochromic(EC)platforms,offering cost-effectiveness and high roundtrip efficiency.However,their practical application remains limited due to the electric field inhomogeneity and the growth of Zn dendrites issues primarily caused by the use of opaque peripheral Zinc(Zn)foils.Herein,we rationally designed a transparent(T=71.4%@633 nm),durable and flexible Ag-PVDF(polyvinylidene difluoride)coated Zinc(AP@Zn)mesh electrode.The AP@Zn mesh promotes a homogeneous electric field and potential distribution within ZECDs,exhibits excellent corrosion resistance,and possesses a low activation energy(47.59 kJ mol^(-1)).Furthermore,it demonstrates broad compatibility with various EC electrodes.As a result,a 5 cm×5 cm Prussian blue(PB)//AP@Zn achieved fast switching times(t_(c)/tb 2.8 s/2.6 s),high coloration efficiency(157.44 cm^(2)C^(-1)),outstanding cycling stability(93.7%ΔT retention after 500 cycles),and integrated energy storage functionalities(32.89 mA h m^(-2)at 0.02 mA cm^(-2)).A large,scalable 10 cm×10 cm PB//AP@Zn device showed significant faster switching times(t_(c)/tb 6.6 s/5.4 s)compared to the PB//Zn foil counterpart(t_(c)/tb 15 s/11.4 s).Importantly,we also demonstrated devices based on Nb_(18)W_(16)O_(93)(NWO)//AP@Zn,which exhibited fast switching(t_(c)/tb 18.5 s/20 s)and high durability(77.7%ΔT retention after 1200 cycles),as well as potassium vanadate(KVO)//AP@Zn featuring multicolor capabilities.Stacked PB//AP@Zn//KVO electrochromic displays exhibited a six-color palette including olive green1,tawny,bronzing,olive green2,deep blue-green,cool grayish green.This work underscores the critical role of electrode design in advancing ZECDs towards multifunctional and flexible electronics.
基金State Grid Corporation Headquarters Science and Technology Project,Grant/Award Number:5500-20220110A-1-1-ZN。
文摘Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a long service life.The breaking mechanism significantly affects the current interruption capability of DCCBs.The operation of the repulsion mechanism,along with the morphology of the arc and its transformation within the interrupter chamber,collectively influence the breaking performance of the FMSs.This paper presents a comprehensive analysis of the FMSs,which serves as the pivotal component of controlled resonance combination circuit breakers(CRCBs).This study establishes a multi physics coupling simulation analysis method based on the equivalent circuit of repulsion mechanism discharge,combined with electromagnetic and solid mechanics fields.By constructing a full cycle magnetohydrodynamic particle arc(MHP)model and using a combined simulation of Finite Element joint model(FEJM),the evolution law of arc characteristics during the superimposed current interruption process was systematically explored.The focus was on analysing the physical process of the zero zone of the superimposed arc,the multi physics field coupling relationship of the arc,and the interaction mechanism with external characteristic parameters.Further combining with optimisation design methods,the effectiveness of the model was verified through experiments,FEJM provides comprehensive technical support for effectively reflecting the stress issues of core components during the breaking process of FMS and can provide accurate theoretical references for the optimisation design of mechanical motion components in FMS.It also accurately represents the arc extinguishing process during the breaking of FMS and provides a convenient method for the selection and design of circuit parameters for the entire circuit breaker.
基金supported by the National Key Research and Development Program of China(No.2022YFA1405000)the National Natural Science Foundation of China(No.62375141)+2 种基金the Major Project of Natural Science Foundation of Jiangsu Province(No.20243067)the Natural Science Foundation of Guangdong Province(No.2024B1515040023)the GJYC program of Guangzhou(No.2024D03J0002)。
文摘Polymer-embedded liquid crystals(LCs)play a pivotal role in smart applications,enabling precise tunability over electrooptical properties.However,high energy consumption in conventional LC-polymeric systems limits their efficiency in sustainable and environmental protection technologies.Reducing driving voltage without compromising mechanical and electro-optical performance remains an unresolved challenge.Here,we demonstrate a polymer-confined ferroelectric nematic(N_(F))liquid crystal system,polymerized with mesogenic and non-mesogenic monomers under an electric field.The effective multidomain polymer structure exploits the intriguing properties of the NFLC and generates a highly scattered state with an excellent contrast ratio in the N_(F)phase.Electric field-controlled reorientation of directors leads to a transparent state at a very small voltage.The system demonstrates the advantages of a low driving voltage,sub-millisecond switching time with negligible hysteresis,and improved durability,promoting applications in energy-saving smart windows.This work reveals valuable insights into leveraging NFLCs and tailoring polymer networks to advance the performance of electro-optic devices.
基金supported by the National Natural Science Foundation of China(Nos.51703199 and 51673174)Natural Science Foundation of Zhejiang Province of China(NO.LZ17E030001).
文摘An imidazolium-based ionic liquid(IL)modified triphenylamine derivative,namely 1-(4-((4-(diphenylamino)benzoyl)oxy)butyl)-3-methyl imidazole tetrafluoroborate(TPAC_(6)IL-BF_(4)),was designed and synthesized,and further applied with 3,4-ethylene dioxythiophene(EDOT)to prepare conjugated copolymer P(EDOT:TPAC_(6)IL-BF_(4)) via electrochemical polymerization.The cyclic voltammetry curves show that the copolymer P(EDOT:TPAC_(6)IL-BF_(4))possesses two pairs of redox peaks,which should be ascribed to the redox behaviors of EDOT and triphenylamine.The ultraviolet-visible(UV-Vis)absorption spectrum of P(EDOT:TPAC_(6)IL-BF_(4))exhibits one maximum absorption peak at 580 nm and a small shoulder characteristic peak at 385 nm under neutral state which are assigned toπ-π^(*)conjugated structure of EDOT and triphenylamine.After being applied at the positive voltage,the copolymer color changes from dark blue to light blue,which is close to the color of poly(3,4-ethylenedioxythiophene)(PEDOT).Surprisingly,the copolymer P(EDOT:TPAC_(6)IL-BF_(4))shows shorter switching time of 0.37 s,0.30 s at 580 nm and 0.38 s,0.45 s at 1100 nm compared with PEDOT.It is more intriguing that the copolymer P(EDOT:TPAC_(6)IL-BF_(4))exhibits electrochromism even in free supporting electrolyte.The results confirm that the existence of imidazolium-based ionic liquid has an improvement on the ion diffusion properties and the switching time of conjugated polymer,which may provide a potential direction for the preparation of high-performance electrochromic materials.
基金supported by Postdoctoral Innovative Talent Support Program under Grant BX20190059the China Postdoctoral Science Foundation under Grant 2019M660235+1 种基金the Sichuan Science and Technology Program under Project 2018JY0555the Science and Technology on Analog Integrated Circuit Laboratory under Project 6142802180509。
文摘A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side,and double trenches together with an N-type carrier storage(N-CS)layer at the cathode side,named DT-NPN LIGBT.The NPN structure not only acts as an electron barrier to eliminate the snapback effect in the on-state within a smaller cell pitch but also provides an extra electron extracting path during the turn-off stage to decrease the turnoff loss(E_(off)).The double cathode trenches and N-CS layer hinder the hole from being extracted by the cathode quickly.They then enhance carrier storing effect and lead to a reduced on-state voltage drop(V_(on)).The latch-up immunity is improved by the double cathode trenches.Hence,the DT-NPN LIGBT obtains a superior tradeoff between the V_(on)and E_(off).Additionally,the DT-NPN LIGBT exhibits an improved blocking capability and weak dependence of breakdown voltage(BV)on the P+anode doping concentration because the NPN structure suppresses triggering the PNP transistor.The proposed LIGBT reduces the E_(off)by 55%at the same V_(on),and improves the BV by 7.3%compared to the conventional LIGBT.
文摘Titration of pesticides onto sorption sites can determine sorption capacities on soils. Previous studies have tracked the sorption capacities and detailed kinetics of the uptake of atrazine and its decomposition byproduct hydroxyatrazine on different soils, including measurements made using LC-MS/MS. These studies have now been extended to explore sorption-desorption equilibria for a mixture of pesticides from soil using LC-MS/MS. Desorption of sorbed pesticide residues has environmental regulatory implications for pesticide levels in runoff, or for longer term sequestration, partitioning, and transport. The uptake of pesticides by the soil at equilibrium was measured for a number of different concentrations, and sorption capacities were estimated. Pesticide-soil interaction studies were conducted by exposing standard stock solutions of pesticide mixtures to a characterized Nova Scotia soil. The mixture contained atrazine and dicamba. Initial aqueous mixture concentrations ranging from 5 × 10<sup>-9</sup> to 10<sup>-5</sup> M or greater were exposed to 25 mg aliquots of soil and allowed to reach equilibrium. The total uptake of each pesticide was measured indirectly, by measuring the concentration remaining in solution using an IONICS 3Q 120 triple quadrupole mass spectrometer. These sorption capacities have been supplemented by studies examining equilibrium recovery rates from soil aliquots with different initial uptakes. This gives insight into the fraction of easily recoverable (reversibly sorbed) pesticides on the soil. Proper quantification of equilibrium constants and kinetic rate coefficients using high performance LC-MS/MS facilitates the construction of accurate, predictive models. Predictive kinetic models can successfully mimic the experimental results for solution concentration, labile sorption, and intra-particle diffusion, and could be used to guide regulatory practices.
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.
基金Project supported by the State Key Project of Science and Technology,China(No.2011ZX02706-003)
文摘A novel high performance carrier stored trench bipolar transistor （CSTBT） with a field- modified P-base region is proposed. Due to the p-pillars inserted into the drift region extending the P-base region to the bottom of the trench gate, the electric field around the trench gate is modified, preventing the CSTBT from breakdown in advance caused by a concentration of the electric field at the edge of the trench gate. The p-pillars under the p-well forming the novel P-base region also provide extra paths for hole transportation. Thus, the switching time is also reduced. Simulation results have shown that the blocking voltage （BV） of the novel CSTBT is almost 430 V higher exhibiting avalanche breakdown properties compared with the conventional CSTBT. Moreover, the turn-off time of the novel structure is 0.3μs （17%） shorter than the conventional CSTBT with the same gate length.
