High-power direct current fast charging(DC-HPC),particularly for megawatt-level charging currents(≥1000 A),is expected to significantly reduce charging time and improve electric vehicle durability,despite the risk of...High-power direct current fast charging(DC-HPC),particularly for megawatt-level charging currents(≥1000 A),is expected to significantly reduce charging time and improve electric vehicle durability,despite the risk of instantaneous thermal shocks.Conventional cooling methods,which separately transmit current and heat,struggle to achieve both flexible maneuverability and high-efficiency cooling.In this study,we present a synergetic cooling and transmission strategy using a gallium-based liquid metal flexible charging connector(LMFCC),which efficiently dissipates ultra-high heat flux while simultaneously carrying superhigh current.The LMFCC exhibits exceptional flexible operability(bending radius of 2 cm)and transmission stability even under significant deformation owing to the excellent liquidity and conductivity of liquid metal(LM).These properties are markedly better than those of solid metal connector.A compact induction electromagnet-driven method is optimized to significantly increase the LM flow rate and the active cooling capacity,resulting in sudden low temperature(<16℃at 1000 A).This synergetic cooling and charging strategy are expected to enable ultrahigh-heat-flux thermal management and accelerate development of the electric vehicle industry.展开更多
Electric vehicles are pivotal in the global shift toward decarbonizing road transport,with lithium-ion batteries at the heart of this technological evolution.However,the pursuit of batteries capable of extremely fast ...Electric vehicles are pivotal in the global shift toward decarbonizing road transport,with lithium-ion batteries at the heart of this technological evolution.However,the pursuit of batteries capable of extremely fast charging that also satisfy high energy and safety criteria,poses a significant challenge to current lithium-ion batteries technologies.Additionally,the increasing demand for aluminum(Al)and copper(Cu)in electrification,solar energy technologies,and vehicle light-eighting is driving these metals toward near-critical status in the medium term.This study introduces metalized polythylene terephthalate(mPET)polymer films by depositing an Al or Cu thin layer onto two sides of a polyethylene terephthalate film—named mPET/Al and mPET/Cu,as lightweight,cost-effective alternatives to traditional metal current collectors in lithium-ion batteries.We have fabricated current collectors that significantly reduce weight(by 73%),thickness(by 33%),and cost(by 85%)compared with traditional metal foil counterparts.These advancements have the potential to enhance energy density to 280 Wh kg^(-1) at the electrode level under 10-min charging at 6 C.Through testing,including a novel extremely fast charging protocol across various C-rates and long-term cycling(up to 1000 cycles)in different cell configurations,the superior performance of these metalized polymer films has been demonstrated.Notably,mPET/Cu and mPET/Al films exhibited comparable capacities to conventional cells under extremely fast charging,with the mPET cells showing a 27%improvement in energy density at 6 C and maintaining significant energy density after 1000 cycles.This study underscores the potential of mPET films to revolutionize the roll-to-roll battery manufacturing process and significantly advance the performance metrics of lithium-ion batteries in electric vehicles applications.展开更多
The incremental capacity analysis(ICA)technique is notably limited by its sensitivity to variations in charging conditions,which constrains its practical applicability in real-world scenarios.This paper introduces an ...The incremental capacity analysis(ICA)technique is notably limited by its sensitivity to variations in charging conditions,which constrains its practical applicability in real-world scenarios.This paper introduces an ICA-compensation technique to address this limitation and propose a generalized framework for assessing the state of health(SOH)of batteries based on ICA that is applicable under differing charging conditions.This novel approach calculates the voltage profile under quasi-static conditions by subtracting the voltage increase attributable to the additional polarization effects at high currents from the measured voltage profile.This approach's efficacy is contingent upon precisely acquiring the equivalent impedance.To obtain the equivalent impedance throughout the batteries'lifespan while minimizing testing costs,this study employs a current interrupt technique in conjunction with a long short-term memory(LSTM)network to develop a predictive model for equivalent impedance.Following the derivation of ICA curves using voltage profiles under quasi-static conditions,the research explores two scenarios for SOH estimation:one utilizing only incremental capacity(IC)features and the other incorporating both IC features and IC sampling.A genetic algorithm-optimized backpropagation neural network(GABPNN)is employed for the SOH estimation.The proposed generalized framework is validated using independent training and test datasets.Variable test conditions are applied for the test set to rigorously evaluate the methodology under challenging conditions.These evaluation results demonstrate that the proposed framework achieves an estimation accuracy of 1.04%for RMSE and 0.90%for MAPE across a spectrum of charging rates ranging from 0.1 C to 1 C and starting SOCs between 0%and 70%,which constitutes a major advancement compared to established ICA methods.It also significantly enhances the applicability of conventional ICA techniques in varying charging conditions and negates the necessity for separate testing protocols for each charging scenario.展开更多
Conventional multi-stage constant current charging strategies often use higher multiples of current to charge the battery in pursuit of shorter charging times.However,this leads to an increase in battery temperature,w...Conventional multi-stage constant current charging strategies often use higher multiples of current to charge the battery in pursuit of shorter charging times.However,this leads to an increase in battery temperature,while shortening the charging time.This in turn affects the safety of the charging process.Furthermore,the higher charging currents are not ideal for shortening the charging time in the later stages of charging.To solve the aforementioned problems,in this study,a multi-stage constant current charging strategy is presented.This strategy can shorten the battery charging time by using the increase in battery temperature during the charging process as a constraint,using a genetic algorithm to calculate the charging current value,and investigating the phased approach to charging.Finally,the charging strategy is experimentally validated at different ambient temperatures and different initial SOCs.The experimental results show that the charging strategy proposed in this paper not only reduces the amount of calculations,but also reduces the temperature rise by up to 46.4%and charging time by up to 4.2%under different operating conditions.展开更多
In field emission under a non-dc voltage, a displacement current is inevitable due to charging the cathode–anode condenser. Under an often-used square voltage pulse, in which the voltage rises from zero to a certain ...In field emission under a non-dc voltage, a displacement current is inevitable due to charging the cathode–anode condenser. Under an often-used square voltage pulse, in which the voltage rises from zero to a certain value abruptly, the charging current in the circuit is very large at the rising and falling edges. This large charging current makes measurement of the actual emissive current from the cathode difficult, constitutes a threat to the components in the circuit and causes attenuation of the emissive current within the pulse. To alleviate these drawbacks, trapezoid voltage pulses, whose rising edges are extended dramatically in comparison with square voltage pulses, are employed to extract the field emission. Under a trapezoid voltage pulse, the charging current is clearly lowered as expected. Furthermore, the heat generated by the charging current under the trapezoid voltage pulse is much smaller than that under the square voltage pulse. Hence the emissive current does not show any attenuation within the pulse. Finally, the average emissive currents are found to decrease with the repetition frequency of the pulses.展开更多
The current-voltage（I-V） characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, an...The current-voltage（I-V） characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, and the resulting curves are all similar in shape. When a voltage of about 560V is applied to the cBN crystal, the emitted light is visible to the naked eye in a dark room. We explain these phenomena by the space charge limited current and the electronic transition between the X and Г valleys of the conduction band.展开更多
通过原位电化学充氢方法(电流密度0、2和4 m A/cm^(2))研究了45Cr Ni MoVA钢的低周疲劳行为及其断裂机制。结果表明:该材料在循环加载过程中呈现出应变幅值依赖的非饱和循环软化现象和non-Masing特性,其中non-Masing行为在低应变幅条件...通过原位电化学充氢方法(电流密度0、2和4 m A/cm^(2))研究了45Cr Ni MoVA钢的低周疲劳行为及其断裂机制。结果表明:该材料在循环加载过程中呈现出应变幅值依赖的非饱和循环软化现象和non-Masing特性,其中non-Masing行为在低应变幅条件下表现尤为显著。尽管充氢电流密度对材料的循环滞回行为无明显影响,但材料的抗疲劳性能却明显依赖于充氢电流密度大小和应变幅值。随着充氢电流密度的增加,材料内部氢浓度增高,导致疲劳损伤加速累积,且高应变幅工况下氢致寿命劣化效应显著高于低应变幅工况。扫描电镜(SEM)断口分析表明,充氢显著改变了材料的疲劳断裂机制:未充氢试样呈现典型的表面裂纹萌生与韧性断裂特征;而随充氢电流密度和应变幅值的提高,充氢试样的裂纹萌生位置由试样表面向内部缺陷转移,且脆性特征(准解理与沿晶分离形态)显著增强。充氢试样裂纹萌生区与扩展区均呈现韧窝、准解理和沿晶分离形态并存的混合断裂特征。展开更多
To reduce the carbon footprint in the transportation sector and improve overall vehicle efficiency,a large number of electric vehicles are being manufactured.This is due to the fact that environmental concerns and the...To reduce the carbon footprint in the transportation sector and improve overall vehicle efficiency,a large number of electric vehicles are being manufactured.This is due to the fact that environmental concerns and the depletion of fossil fuels have become significant global problems.Lithium-ion batteries(LIBs)have been distinguished themselves from alternative energy storage technologies for electric vehicles(EVs) due to superior qualities like high energy and power density,extended cycle life,and low maintenance cost to a competitive price.However,there are still certain challenges to be solved,like EV fast charging,longer lifetime,and reduced weight.For fast charging,the multi-stage constant current(MSCC) charging technique is an emerging solution to improve charging efficiency,reduce temperature rise during charging,increase charging/discharging capacities,shorten charging time,and extend the cycle life.However,there are large variations in the implementation of the number of stages,stage transition criterion,and C-rate selection for each stage.This paper provides a review of these problems by compiling information from the literature.An overview of the impact of different design parameters(number of stages,stage transition,and C-rate) that the MSCC charging techniques have had on the LIB performance and cycle life is described in detail and analyzed.The impact of design parameters on lifetime,charging efficiency,charging and discharging capacity,charging speed,and rising temperature during charging is presented,and this review provides guidelines for designing advanced fast charging strategies and determining future research gaps.展开更多
Interface traps generated under hot carrier (HC) stress in LDD nMOST's are monitored by the direct current current voltage (DCIV) measurement technique and charge pumping (CP) technique.The measured and analyzed...Interface traps generated under hot carrier (HC) stress in LDD nMOST's are monitored by the direct current current voltage (DCIV) measurement technique and charge pumping (CP) technique.The measured and analyzed results show that the D peak in DCIV spectrum,which related to the drain region,is affected by a superfluous drain leakage current.The band trap band tunneling current is dominant of this current.展开更多
Periodically changed current is called pulse current.It has been found that using the pulse current to charge/discharge lithium-ion batteries can improve the safety and cycle stability of the battery.In this short rev...Periodically changed current is called pulse current.It has been found that using the pulse current to charge/discharge lithium-ion batteries can improve the safety and cycle stability of the battery.In this short review,the mechanisms of pulse current improving the performance of lithium-ion batteries are summarized from four aspects:activation,warming up,fast charging and inhibition of lithium dendrites.Related content may help us use the pulse current to improve the performance of lithium-ion batteries and further optimize pulse current technology.展开更多
The corona current pulses generated by corona discharge are the sources of the radio interference from transmission lines and the detailed characteristics of the corona current pulses from conductor should be investig...The corona current pulses generated by corona discharge are the sources of the radio interference from transmission lines and the detailed characteristics of the corona current pulses from conductor should be investigated in order to reveal their generation mechanism.In this paper,the line-to-plane electrodes are designed to measure and analyze the characteristics of corona current pulses from positive corona discharges.The influences of inter-electrode gap and line diameters on the detail characteristics of corona current pulses,such as pulse amplitude,rise time,duration time and repetition frequency,are carefully analyzed.The obtained results show that the pulse amplitude and the repetition frequency increase with the diameter of line electrode when the electric fields on the surface of line electrodes are same.With the increase of inter-electrode gap,the pulse amplitude and the repetition frequency first decrease and then turn to be stable,while the rise time first increases and finally turns to be stable.The distributions of electric field and space charges under the line electrodes are calculated,and the influences of inter-electrode gap and line electrode diameter on the experimental results are qualitatively explained.展开更多
We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction （RSOI）, coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two...We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction （RSOI）, coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two ferromagnetic leads and two quantum dots form a ring threaded by Aharonov-Bohm （AB） flux. This device possesses normal quasiparticle transmission between the two ferromagnetic leads, and normal and crossed Andreev reflections providing conductive holes. For the appropriate spin polarization of the ferromagnetic leads, RSOI and AB flux, the pure spin-up （or spin-down） current without net charge current in the right lead, which is due to the equal numbers of electrons and holes with the same spin-polarization moving along the same direction, can be obtained by adjusting the gate voltage, which may be used in practice as a pure spin-current injector.展开更多
A novel structure for a charge pump circuit is proposed, in which the charge-pump （CP） current can adaptively regulated according to phase-locked loops （PLL） frequency synthesis demand. The current follow technolo...A novel structure for a charge pump circuit is proposed, in which the charge-pump （CP） current can adaptively regulated according to phase-locked loops （PLL） frequency synthesis demand. The current follow technology is used to make perfect current matching characteristics, and the two differential inverters are implanted to increase the speed of charge pump and decrease output spur due to theory of low voltage difference signal. Simulation results, with 1st silicon 0. 25μm 2. 5 V complementary metal-oxide-semiconductor （CMOS） mixed-signal process, show the good current matching characteristics regardless of the charge pump output voltages.展开更多
基金the National Natural Science Foundation of China(NSFC)(52076213)the 2115 Talent Development Program of China Agricultural University for the financial coverage of this work。
文摘High-power direct current fast charging(DC-HPC),particularly for megawatt-level charging currents(≥1000 A),is expected to significantly reduce charging time and improve electric vehicle durability,despite the risk of instantaneous thermal shocks.Conventional cooling methods,which separately transmit current and heat,struggle to achieve both flexible maneuverability and high-efficiency cooling.In this study,we present a synergetic cooling and transmission strategy using a gallium-based liquid metal flexible charging connector(LMFCC),which efficiently dissipates ultra-high heat flux while simultaneously carrying superhigh current.The LMFCC exhibits exceptional flexible operability(bending radius of 2 cm)and transmission stability even under significant deformation owing to the excellent liquidity and conductivity of liquid metal(LM).These properties are markedly better than those of solid metal connector.A compact induction electromagnet-driven method is optimized to significantly increase the LM flow rate and the active cooling capacity,resulting in sudden low temperature(<16℃at 1000 A).This synergetic cooling and charging strategy are expected to enable ultrahigh-heat-flux thermal management and accelerate development of the electric vehicle industry.
文摘Electric vehicles are pivotal in the global shift toward decarbonizing road transport,with lithium-ion batteries at the heart of this technological evolution.However,the pursuit of batteries capable of extremely fast charging that also satisfy high energy and safety criteria,poses a significant challenge to current lithium-ion batteries technologies.Additionally,the increasing demand for aluminum(Al)and copper(Cu)in electrification,solar energy technologies,and vehicle light-eighting is driving these metals toward near-critical status in the medium term.This study introduces metalized polythylene terephthalate(mPET)polymer films by depositing an Al or Cu thin layer onto two sides of a polyethylene terephthalate film—named mPET/Al and mPET/Cu,as lightweight,cost-effective alternatives to traditional metal current collectors in lithium-ion batteries.We have fabricated current collectors that significantly reduce weight(by 73%),thickness(by 33%),and cost(by 85%)compared with traditional metal foil counterparts.These advancements have the potential to enhance energy density to 280 Wh kg^(-1) at the electrode level under 10-min charging at 6 C.Through testing,including a novel extremely fast charging protocol across various C-rates and long-term cycling(up to 1000 cycles)in different cell configurations,the superior performance of these metalized polymer films has been demonstrated.Notably,mPET/Cu and mPET/Al films exhibited comparable capacities to conventional cells under extremely fast charging,with the mPET cells showing a 27%improvement in energy density at 6 C and maintaining significant energy density after 1000 cycles.This study underscores the potential of mPET films to revolutionize the roll-to-roll battery manufacturing process and significantly advance the performance metrics of lithium-ion batteries in electric vehicles applications.
基金funded by the Bavarian State Ministry of ScienceResearch and Art(Grant number:H.2-F1116.WE/52/2)。
文摘The incremental capacity analysis(ICA)technique is notably limited by its sensitivity to variations in charging conditions,which constrains its practical applicability in real-world scenarios.This paper introduces an ICA-compensation technique to address this limitation and propose a generalized framework for assessing the state of health(SOH)of batteries based on ICA that is applicable under differing charging conditions.This novel approach calculates the voltage profile under quasi-static conditions by subtracting the voltage increase attributable to the additional polarization effects at high currents from the measured voltage profile.This approach's efficacy is contingent upon precisely acquiring the equivalent impedance.To obtain the equivalent impedance throughout the batteries'lifespan while minimizing testing costs,this study employs a current interrupt technique in conjunction with a long short-term memory(LSTM)network to develop a predictive model for equivalent impedance.Following the derivation of ICA curves using voltage profiles under quasi-static conditions,the research explores two scenarios for SOH estimation:one utilizing only incremental capacity(IC)features and the other incorporating both IC features and IC sampling.A genetic algorithm-optimized backpropagation neural network(GABPNN)is employed for the SOH estimation.The proposed generalized framework is validated using independent training and test datasets.Variable test conditions are applied for the test set to rigorously evaluate the methodology under challenging conditions.These evaluation results demonstrate that the proposed framework achieves an estimation accuracy of 1.04%for RMSE and 0.90%for MAPE across a spectrum of charging rates ranging from 0.1 C to 1 C and starting SOCs between 0%and 70%,which constitutes a major advancement compared to established ICA methods.It also significantly enhances the applicability of conventional ICA techniques in varying charging conditions and negates the necessity for separate testing protocols for each charging scenario.
基金supported by National Natural Science Foundation of China (Grant No. 51677058)
文摘Conventional multi-stage constant current charging strategies often use higher multiples of current to charge the battery in pursuit of shorter charging times.However,this leads to an increase in battery temperature,while shortening the charging time.This in turn affects the safety of the charging process.Furthermore,the higher charging currents are not ideal for shortening the charging time in the later stages of charging.To solve the aforementioned problems,in this study,a multi-stage constant current charging strategy is presented.This strategy can shorten the battery charging time by using the increase in battery temperature during the charging process as a constraint,using a genetic algorithm to calculate the charging current value,and investigating the phased approach to charging.Finally,the charging strategy is experimentally validated at different ambient temperatures and different initial SOCs.The experimental results show that the charging strategy proposed in this paper not only reduces the amount of calculations,but also reduces the temperature rise by up to 46.4%and charging time by up to 4.2%under different operating conditions.
基金Supported by the Natural Science Foundation of Jiangsu Province of China under Grant Nos BK20161243 and BK20161242the National Natural Science Foundation of China under Grant No 61774007
文摘In field emission under a non-dc voltage, a displacement current is inevitable due to charging the cathode–anode condenser. Under an often-used square voltage pulse, in which the voltage rises from zero to a certain value abruptly, the charging current in the circuit is very large at the rising and falling edges. This large charging current makes measurement of the actual emissive current from the cathode difficult, constitutes a threat to the components in the circuit and causes attenuation of the emissive current within the pulse. To alleviate these drawbacks, trapezoid voltage pulses, whose rising edges are extended dramatically in comparison with square voltage pulses, are employed to extract the field emission. Under a trapezoid voltage pulse, the charging current is clearly lowered as expected. Furthermore, the heat generated by the charging current under the trapezoid voltage pulse is much smaller than that under the square voltage pulse. Hence the emissive current does not show any attenuation within the pulse. Finally, the average emissive currents are found to decrease with the repetition frequency of the pulses.
文摘The current-voltage（I-V） characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, and the resulting curves are all similar in shape. When a voltage of about 560V is applied to the cBN crystal, the emitted light is visible to the naked eye in a dark room. We explain these phenomena by the space charge limited current and the electronic transition between the X and Г valleys of the conduction band.
文摘通过原位电化学充氢方法(电流密度0、2和4 m A/cm^(2))研究了45Cr Ni MoVA钢的低周疲劳行为及其断裂机制。结果表明:该材料在循环加载过程中呈现出应变幅值依赖的非饱和循环软化现象和non-Masing特性,其中non-Masing行为在低应变幅条件下表现尤为显著。尽管充氢电流密度对材料的循环滞回行为无明显影响,但材料的抗疲劳性能却明显依赖于充氢电流密度大小和应变幅值。随着充氢电流密度的增加,材料内部氢浓度增高,导致疲劳损伤加速累积,且高应变幅工况下氢致寿命劣化效应显著高于低应变幅工况。扫描电镜(SEM)断口分析表明,充氢显著改变了材料的疲劳断裂机制:未充氢试样呈现典型的表面裂纹萌生与韧性断裂特征;而随充氢电流密度和应变幅值的提高,充氢试样的裂纹萌生位置由试样表面向内部缺陷转移,且脆性特征(准解理与沿晶分离形态)显著增强。充氢试样裂纹萌生区与扩展区均呈现韧窝、准解理和沿晶分离形态并存的混合断裂特征。
文摘To reduce the carbon footprint in the transportation sector and improve overall vehicle efficiency,a large number of electric vehicles are being manufactured.This is due to the fact that environmental concerns and the depletion of fossil fuels have become significant global problems.Lithium-ion batteries(LIBs)have been distinguished themselves from alternative energy storage technologies for electric vehicles(EVs) due to superior qualities like high energy and power density,extended cycle life,and low maintenance cost to a competitive price.However,there are still certain challenges to be solved,like EV fast charging,longer lifetime,and reduced weight.For fast charging,the multi-stage constant current(MSCC) charging technique is an emerging solution to improve charging efficiency,reduce temperature rise during charging,increase charging/discharging capacities,shorten charging time,and extend the cycle life.However,there are large variations in the implementation of the number of stages,stage transition criterion,and C-rate selection for each stage.This paper provides a review of these problems by compiling information from the literature.An overview of the impact of different design parameters(number of stages,stage transition,and C-rate) that the MSCC charging techniques have had on the LIB performance and cycle life is described in detail and analyzed.The impact of design parameters on lifetime,charging efficiency,charging and discharging capacity,charging speed,and rising temperature during charging is presented,and this review provides guidelines for designing advanced fast charging strategies and determining future research gaps.
文摘Interface traps generated under hot carrier (HC) stress in LDD nMOST's are monitored by the direct current current voltage (DCIV) measurement technique and charge pumping (CP) technique.The measured and analyzed results show that the D peak in DCIV spectrum,which related to the drain region,is affected by a superfluous drain leakage current.The band trap band tunneling current is dominant of this current.
基金financially supported by the Science and Technology Program of State Grid Corporation of China(Program Title:Research on Health Improvement Technology of Lithium Iron Phosphate Battery)。
文摘Periodically changed current is called pulse current.It has been found that using the pulse current to charge/discharge lithium-ion batteries can improve the safety and cycle stability of the battery.In this short review,the mechanisms of pulse current improving the performance of lithium-ion batteries are summarized from four aspects:activation,warming up,fast charging and inhibition of lithium dendrites.Related content may help us use the pulse current to improve the performance of lithium-ion batteries and further optimize pulse current technology.
基金supported by National Natural Science Foundation of China under Grant No.51707066by the Fundamental Research Funds for the Central Universities under Grant No.2017 MS004 and No.XCA17003-04
文摘The corona current pulses generated by corona discharge are the sources of the radio interference from transmission lines and the detailed characteristics of the corona current pulses from conductor should be investigated in order to reveal their generation mechanism.In this paper,the line-to-plane electrodes are designed to measure and analyze the characteristics of corona current pulses from positive corona discharges.The influences of inter-electrode gap and line diameters on the detail characteristics of corona current pulses,such as pulse amplitude,rise time,duration time and repetition frequency,are carefully analyzed.The obtained results show that the pulse amplitude and the repetition frequency increase with the diameter of line electrode when the electric fields on the surface of line electrodes are same.With the increase of inter-electrode gap,the pulse amplitude and the repetition frequency first decrease and then turn to be stable,while the rise time first increases and finally turns to be stable.The distributions of electric field and space charges under the line electrodes are calculated,and the influences of inter-electrode gap and line electrode diameter on the experimental results are qualitatively explained.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10775091,10774094,10974124,and 11047172)the Excellent Youth and Midlife Scientist Scientific Research Encouragement Foundation of Shandong Province,China(Grant No. BS2010DS006)the Doctor Research Startup Foundation of Linyi University,China (Grant No. BS201023)
文摘We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction （RSOI）, coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two ferromagnetic leads and two quantum dots form a ring threaded by Aharonov-Bohm （AB） flux. This device possesses normal quasiparticle transmission between the two ferromagnetic leads, and normal and crossed Andreev reflections providing conductive holes. For the appropriate spin polarization of the ferromagnetic leads, RSOI and AB flux, the pure spin-up （or spin-down） current without net charge current in the right lead, which is due to the equal numbers of electrons and holes with the same spin-polarization moving along the same direction, can be obtained by adjusting the gate voltage, which may be used in practice as a pure spin-current injector.
文摘A novel structure for a charge pump circuit is proposed, in which the charge-pump （CP） current can adaptively regulated according to phase-locked loops （PLL） frequency synthesis demand. The current follow technology is used to make perfect current matching characteristics, and the two differential inverters are implanted to increase the speed of charge pump and decrease output spur due to theory of low voltage difference signal. Simulation results, with 1st silicon 0. 25μm 2. 5 V complementary metal-oxide-semiconductor （CMOS） mixed-signal process, show the good current matching characteristics regardless of the charge pump output voltages.
