Based on the hierarchical equations of motion(HEOM)calculation,we theoretically investigate the corresponding control of a triangular triple-quantum-dots(TTQD)ring which is connected to two reservoirs.We initially dem...Based on the hierarchical equations of motion(HEOM)calculation,we theoretically investigate the corresponding control of a triangular triple-quantum-dots(TTQD)ring which is connected to two reservoirs.We initially demonstrate by adding bias voltage and further adjusting the coupling strength between quantum dots,the chiral current induced by bias will go through a transformation of clockwise to counterclockwise direction and an unprecedented effective Hall angle will be triggered.The transformation is very rapid,with a corresponding characteristic time of 80-200 ps.In addition,by adding a magnetic flux to compensate for the chiral current in the original system,we elucidate the relationship between the applied magnetic flux and the Berry phase,which can realize direct measurement of the chiral current and reveal the magnetoelectric coupling relationship.展开更多
This paper proposed a high-sensitivity phase imaging eddy current magneto-optical (PI-ECMO) system for carbon fiber reinforced polymer (CFRP) defect detection. In contrast to other eddy current-based detection systems...This paper proposed a high-sensitivity phase imaging eddy current magneto-optical (PI-ECMO) system for carbon fiber reinforced polymer (CFRP) defect detection. In contrast to other eddy current-based detection systems, the proposed system employs a fixed position excitation coil while enabling the detection point to move within the detection region. This configuration effectively mitigates the interference caused by the lift-off effect, which is commonly observed in systems with moving excitation coils. Correspondingly, the relationship between the defect characteristics (orientation and position) and the surface vertical magnetic field distribution (amplitude and phase) is studied in detail by theoretical analysis and numerical simulations. Experiments conducted on woven CFRP plates demonstrate that the designed PI-ECMO system is capable of effectively detecting both surface and internal cracks, as well as impact defects. The excitation current is significantly reduced compared with traditional eddy current magneto-optical (ECMO) systems.展开更多
A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequenc...A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.展开更多
The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated vol...The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated voltage. According to the realistic conditions of test stations in China, a control device based on pre-arcing current detection and phase control is proposed in this paper. A sample of the control device made up of DSP TMS320LF2407A is fabricated, in which the CPLD MAX7064 is used to transmit signals for EMC design. It can be applied in full voltage synthetic making test at a level of 126kV/63kA. The test results show that, it is accurate to control the making phase of the applied voltage, whether the closing is demanded at voltage peak or zero.展开更多
Powder in tube process(PIT) was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment(HT1), intermediate rolling(IR), and second heat treat...Powder in tube process(PIT) was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment(HT1), intermediate rolling(IR), and second heat treatment(HT2) was performed. The phase evolution mechanism and microstructure changes during these heat treatment processes were systematically discussed. The influences of HT1 parameters on the phase evolution process of Bi-2223 tapes were discussed. With the optimized HT1 process, a proper Bi-2223 content of about 90% was achieved. HT2 process was also optimized by adding a post annealing process. An obvious increase of current capacity was obtained due to the enhancement of intergrain connections. Single filament Bi-2223 tapes with the critical current of Ic-90 A were fabricated with the optimized sintering process.展开更多
The current–phase relations of a ring-trapped Bose–Einstein condensate interrupted by a rotating rectangular barrier are extensively investigated with an analytical solution. A current–phase diagram, single and mul...The current–phase relations of a ring-trapped Bose–Einstein condensate interrupted by a rotating rectangular barrier are extensively investigated with an analytical solution. A current–phase diagram, single and multi-valued relation, is presented with a rescaled barrier height and width. Our results show that the finite size makes the current–phase relation deviate a little bit from the cosine form for the soliton solution in the limit of a vanishing barrier, and the periodic boundary condition selects only the plane wave solution in the case of high barrier. The reason for multi-valued current–phase relation is given by investigating the behavior of soliton solution.展开更多
This article gives an overview of the main passive solutions and active techniques, based on AC switches to limit inrush currents in medium power AC-DC converters (up to 3.7 kW) for electric vehicle charging systems...This article gives an overview of the main passive solutions and active techniques, based on AC switches to limit inrush currents in medium power AC-DC converters (up to 3.7 kW) for electric vehicle charging systems. In particular, a strategy, based on SCR (silicon controlled rectifier) phase, shift control in a mixed rectifier bridge with diodes and thyristors, is proposed. The challenge is to help designers optimize the triggering delay of SCRs to both limit the peak value of inrush current spikes and optimize the charge duration of the DC-link capacitor. A mathematical model (Mathcad engineering tool) has been defined to point out, the interest of a variable triggering delay to control SCRs to meet the expectations described previously. Experimental measurements using an industrial evaluation board of the AC-DC converter demonstrate the robustness of the method.展开更多
The asymmetric dual-three phase BLDC motor has two sets of stator windings,in which the back EMF coefficients are different.This paper takes advantage of the asymmetric dual-three phase BLDC motor’s structural featur...The asymmetric dual-three phase BLDC motor has two sets of stator windings,in which the back EMF coefficients are different.This paper takes advantage of the asymmetric dual-three phase BLDC motor’s structural features and proposes a new method for the accelerated problem of the BLDC motor operating in the high speed and the constant electromagnetic power.The dual phase windings of the BLDC motor are integrated into the circuit in the starting stage.When the motor’s back EMF value is equal to the terminal voltage value,switch off a set of RST three phase windingswhose back EMF coefficient is bigger and make the other set of stator windingUVWwith smaller back EMF coefficient continue to operate under the rated power.As the motor rotor speed continues to increase,the electromagnetic torque remains unchanged.By using the peak current control strategy,we can deduce that the phase current of the UVW three-phase winding is twice the RSTthree-phase windingwhen the asymmetric dual-three phase BLDC motor operates at high speed and constant power.展开更多
The equation governing the motion of a quantum particle is considered in nonrelativistic non-commutative phase space. For this aim, we first study new Poisson brackets in non-commutative phase space and obtain the mod...The equation governing the motion of a quantum particle is considered in nonrelativistic non-commutative phase space. For this aim, we first study new Poisson brackets in non-commutative phase space and obtain the modified equations of motion. Next, using novel transformations, we solve the equation of motion and report the exact analytical solutions.展开更多
The relaxation oscillation of the phase change memory (PCM) devices based on the Ge2Sb2Te5 material is investigated by applying square current pulses. The current pulses with different amplitudes could be accurately...The relaxation oscillation of the phase change memory (PCM) devices based on the Ge2Sb2Te5 material is investigated by applying square current pulses. The current pulses with different amplitudes could be accurately given by the independently designed current testing system. The relaxation oscillation across the PCM device could be measured using an oscilloscope. The oscillation duration decreases with time, showing an inner link with the shrinking threshold voltage Vth. However, the relaxation oscillation would not terminate until the remaining voltage Von reaches the holding voltage Vh. This demonstrates that the relaxation oscillation might be controlled by Von. The increasing current amplitudes could only quicken the oscillation velocity but not be able to eliminate it, which indicates that the relaxation oscillation might be an inherent behavior for the PCM cell.展开更多
According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze's power definition is proposed. Th...According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze's power definition is proposed. The results of theoretical analysis and simula- tion show that the proposed method is effective in realtime detecting of instantaneous harmonic and reactive currents in single-phase circuits. When only detecting the total reactive currents, this method does not need a phase-locked loop circuit, and it also can be used in some special applications to provide different compensations on the ground of different requirements of electric network. Compared with the other methods based on the theory of instantaneous reactive power, this method is simple and easy to realize.展开更多
To investigate the affect of direct current electric field (DCEF) on the interfacial phase,in this paper,a hydrophobic ionic liquid (HIL)/water as liquid-liquid two-phase binary system is established by using the deio...To investigate the affect of direct current electric field (DCEF) on the interfacial phase,in this paper,a hydrophobic ionic liquid (HIL)/water as liquid-liquid two-phase binary system is established by using the deioned water and l-butyl-3-methyl imidazolium hexafluorophosphate,and the topographies of the HIL nanodroplets and nanolayers in ambient water are observed by atomic force microscope (AFM).The results show the AFM exerting the DCEF can enhance the intersolubility of the HIL/water binary system and induce their interfacial phase transfer.展开更多
目的:研究双侧经颅直流电刺激(dual-hemispheric transcranial direct current stimulation,Dual-tDCS)对慢性期脑卒中患者上肢运动功能的影响,为治疗慢性期脑卒中上肢功能障碍提供基于神经机制的理论依据。方法:选取某院24例慢性期脑...目的:研究双侧经颅直流电刺激(dual-hemispheric transcranial direct current stimulation,Dual-tDCS)对慢性期脑卒中患者上肢运动功能的影响,为治疗慢性期脑卒中上肢功能障碍提供基于神经机制的理论依据。方法:选取某院24例慢性期脑卒中上肢运动功能障碍患者,按照随机数字表法将其分为研究组(n=13)和对照组(n=11)。对照组采用tDCS伪刺激联合常规康复治疗,研究组采用Dual-tDCS联合常规康复治疗。治疗前后,采用Fugl-Meyer运动功能评定量表上肢部分(Fugl-Meyer assessment upper limb scale,FMA-UL)及日常生活活动能力(activities of daily living,ADL)测评量表对患者活动能力进行评估。对比治疗前后初级运动皮层(M1区)与全脑功能连接(functional connectivity,FC)的变化。使用SPSS 24.0统计学软件进行数据分析。结果:治疗后,2组患者的FMA-UL、ADL评分比治疗前均显著提高,且研究组评分明显高于对照组,差异有统计学意义(P<0.05)。M1区与全脑FC分析显示,治疗后对照组健侧M1区到患侧枕中回、健侧舌回、健侧角回FC降低(P<0.01);患侧M1区未见FC变化脑区。治疗后研究组健侧M1区到健侧小脑、健侧小脑蚓部FC降低,到患侧中央前回FC增加(P<0.01);患侧M1区到患侧小脑、患侧颞中回FC增加,到健侧中央前回FC降低(P<0.01)。结论:Dual-tDCS对大脑的神经调控作用可改善慢性期卒中患者运动和非运动相关脑区的FC,可能是慢性期脑卒中上肢运动功能障碍的康复机制。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774418,11374363,11674317,11974348,11834014,and 21373191)the Strategic Priority Research Program of CAS(Grant Nos.XDB28000000 and XDB33000000)the Training Program of Major Research Plan of NSFC(Grant No.92165105)。
文摘Based on the hierarchical equations of motion(HEOM)calculation,we theoretically investigate the corresponding control of a triangular triple-quantum-dots(TTQD)ring which is connected to two reservoirs.We initially demonstrate by adding bias voltage and further adjusting the coupling strength between quantum dots,the chiral current induced by bias will go through a transformation of clockwise to counterclockwise direction and an unprecedented effective Hall angle will be triggered.The transformation is very rapid,with a corresponding characteristic time of 80-200 ps.In addition,by adding a magnetic flux to compensate for the chiral current in the original system,we elucidate the relationship between the applied magnetic flux and the Berry phase,which can realize direct measurement of the chiral current and reveal the magnetoelectric coupling relationship.
基金the National Natural Science Foundation of China under Grants No.U2030205,No.62003075,No.61903065,and No.62003074Sichuan Science and Technology Planning Project under Grant No.2022JDJQ0040.
文摘This paper proposed a high-sensitivity phase imaging eddy current magneto-optical (PI-ECMO) system for carbon fiber reinforced polymer (CFRP) defect detection. In contrast to other eddy current-based detection systems, the proposed system employs a fixed position excitation coil while enabling the detection point to move within the detection region. This configuration effectively mitigates the interference caused by the lift-off effect, which is commonly observed in systems with moving excitation coils. Correspondingly, the relationship between the defect characteristics (orientation and position) and the surface vertical magnetic field distribution (amplitude and phase) is studied in detail by theoretical analysis and numerical simulations. Experiments conducted on woven CFRP plates demonstrate that the designed PI-ECMO system is capable of effectively detecting both surface and internal cracks, as well as impact defects. The excitation current is significantly reduced compared with traditional eddy current magneto-optical (ECMO) systems.
文摘A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.
文摘The synthetic making test has been widely used in evaluating the break ability of high-voltage circuit breaker. However, the test research and application are still inadequate, especially in the condition of rated voltage. According to the realistic conditions of test stations in China, a control device based on pre-arcing current detection and phase control is proposed in this paper. A sample of the control device made up of DSP TMS320LF2407A is fabricated, in which the CPLD MAX7064 is used to transmit signals for EMC design. It can be applied in full voltage synthetic making test at a level of 126kV/63kA. The test results show that, it is accurate to control the making phase of the applied voltage, whether the closing is demanded at voltage peak or zero.
基金Funded by the National Natural Science Foundation of China(No.51472206)the National ITER Program of China(2015GB115001)the Program for Innovative Research Team in Shaanxi Province(No.2013KCT-07)
文摘Powder in tube process(PIT) was adopted for the fabrication of single filament Bi-2223 tapes, and a heat treatment process including the first heat treatment(HT1), intermediate rolling(IR), and second heat treatment(HT2) was performed. The phase evolution mechanism and microstructure changes during these heat treatment processes were systematically discussed. The influences of HT1 parameters on the phase evolution process of Bi-2223 tapes were discussed. With the optimized HT1 process, a proper Bi-2223 content of about 90% was achieved. HT2 process was also optimized by adding a post annealing process. An obvious increase of current capacity was obtained due to the enhancement of intergrain connections. Single filament Bi-2223 tapes with the critical current of Ic-90 A were fabricated with the optimized sintering process.
基金Project supported by the National Natural Science Foundation of China(Grant No.11874247)the National Key Research and Development Program of China(Grant Nos.2017YFA0304500 and 2017YFA0304203)+1 种基金PCSIRT,China(Grant No.IRT-17R70)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices,China(Grant No.KF201703)
文摘The current–phase relations of a ring-trapped Bose–Einstein condensate interrupted by a rotating rectangular barrier are extensively investigated with an analytical solution. A current–phase diagram, single and multi-valued relation, is presented with a rescaled barrier height and width. Our results show that the finite size makes the current–phase relation deviate a little bit from the cosine form for the soliton solution in the limit of a vanishing barrier, and the periodic boundary condition selects only the plane wave solution in the case of high barrier. The reason for multi-valued current–phase relation is given by investigating the behavior of soliton solution.
文摘This article gives an overview of the main passive solutions and active techniques, based on AC switches to limit inrush currents in medium power AC-DC converters (up to 3.7 kW) for electric vehicle charging systems. In particular, a strategy, based on SCR (silicon controlled rectifier) phase, shift control in a mixed rectifier bridge with diodes and thyristors, is proposed. The challenge is to help designers optimize the triggering delay of SCRs to both limit the peak value of inrush current spikes and optimize the charge duration of the DC-link capacitor. A mathematical model (Mathcad engineering tool) has been defined to point out, the interest of a variable triggering delay to control SCRs to meet the expectations described previously. Experimental measurements using an industrial evaluation board of the AC-DC converter demonstrate the robustness of the method.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 61773006。
文摘The asymmetric dual-three phase BLDC motor has two sets of stator windings,in which the back EMF coefficients are different.This paper takes advantage of the asymmetric dual-three phase BLDC motor’s structural features and proposes a new method for the accelerated problem of the BLDC motor operating in the high speed and the constant electromagnetic power.The dual phase windings of the BLDC motor are integrated into the circuit in the starting stage.When the motor’s back EMF value is equal to the terminal voltage value,switch off a set of RST three phase windingswhose back EMF coefficient is bigger and make the other set of stator windingUVWwith smaller back EMF coefficient continue to operate under the rated power.As the motor rotor speed continues to increase,the electromagnetic torque remains unchanged.By using the peak current control strategy,we can deduce that the phase current of the UVW three-phase winding is twice the RSTthree-phase windingwhen the asymmetric dual-three phase BLDC motor operates at high speed and constant power.
基金Supported by the China Scholarship Councilthe Hanjiang Scholar Project of Shaanxi University of Technology
文摘The equation governing the motion of a quantum particle is considered in nonrelativistic non-commutative phase space. For this aim, we first study new Poisson brackets in non-commutative phase space and obtain the modified equations of motion. Next, using novel transformations, we solve the equation of motion and report the exact analytical solutions.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDA09020402the National Key Basic Research Program of China under Grant Nos 2013CBA01900,2010CB934300,2011CBA00607 and 2011CB932804+2 种基金the National Integrate Circuit Research Program of China under Grant No 2009ZX02023-003the National Natural Science Foundation of China under Grant Nos 61176122,61106001,61261160500 and 61376006the Science and Technology Council of Shanghai under Grant Nos 12nm0503701,13DZ2295700,12QA1403900,13ZR1447200 and 14ZR1447500
文摘The relaxation oscillation of the phase change memory (PCM) devices based on the Ge2Sb2Te5 material is investigated by applying square current pulses. The current pulses with different amplitudes could be accurately given by the independently designed current testing system. The relaxation oscillation across the PCM device could be measured using an oscilloscope. The oscillation duration decreases with time, showing an inner link with the shrinking threshold voltage Vth. However, the relaxation oscillation would not terminate until the remaining voltage Von reaches the holding voltage Vh. This demonstrates that the relaxation oscillation might be controlled by Von. The increasing current amplitudes could only quicken the oscillation velocity but not be able to eliminate it, which indicates that the relaxation oscillation might be an inherent behavior for the PCM cell.
文摘According to the characteristics of single-phase circuits and demand of using active filter for real-time detecting harmonic and reactive currents, a detecting method based on Fryze's power definition is proposed. The results of theoretical analysis and simula- tion show that the proposed method is effective in realtime detecting of instantaneous harmonic and reactive currents in single-phase circuits. When only detecting the total reactive currents, this method does not need a phase-locked loop circuit, and it also can be used in some special applications to provide different compensations on the ground of different requirements of electric network. Compared with the other methods based on the theory of instantaneous reactive power, this method is simple and easy to realize.
基金Supported by the National Basic Research Program of China (973 Program No. 2007CB936000)the National Natural Science Foundation of China(No.10874198,90923002,21073222 and 10975175,No. 10874030)the Chinese Academy of Sciences (No. KJCX2-EW-N03)
文摘To investigate the affect of direct current electric field (DCEF) on the interfacial phase,in this paper,a hydrophobic ionic liquid (HIL)/water as liquid-liquid two-phase binary system is established by using the deioned water and l-butyl-3-methyl imidazolium hexafluorophosphate,and the topographies of the HIL nanodroplets and nanolayers in ambient water are observed by atomic force microscope (AFM).The results show the AFM exerting the DCEF can enhance the intersolubility of the HIL/water binary system and induce their interfacial phase transfer.
文摘目的:研究双侧经颅直流电刺激(dual-hemispheric transcranial direct current stimulation,Dual-tDCS)对慢性期脑卒中患者上肢运动功能的影响,为治疗慢性期脑卒中上肢功能障碍提供基于神经机制的理论依据。方法:选取某院24例慢性期脑卒中上肢运动功能障碍患者,按照随机数字表法将其分为研究组(n=13)和对照组(n=11)。对照组采用tDCS伪刺激联合常规康复治疗,研究组采用Dual-tDCS联合常规康复治疗。治疗前后,采用Fugl-Meyer运动功能评定量表上肢部分(Fugl-Meyer assessment upper limb scale,FMA-UL)及日常生活活动能力(activities of daily living,ADL)测评量表对患者活动能力进行评估。对比治疗前后初级运动皮层(M1区)与全脑功能连接(functional connectivity,FC)的变化。使用SPSS 24.0统计学软件进行数据分析。结果:治疗后,2组患者的FMA-UL、ADL评分比治疗前均显著提高,且研究组评分明显高于对照组,差异有统计学意义(P<0.05)。M1区与全脑FC分析显示,治疗后对照组健侧M1区到患侧枕中回、健侧舌回、健侧角回FC降低(P<0.01);患侧M1区未见FC变化脑区。治疗后研究组健侧M1区到健侧小脑、健侧小脑蚓部FC降低,到患侧中央前回FC增加(P<0.01);患侧M1区到患侧小脑、患侧颞中回FC增加,到健侧中央前回FC降低(P<0.01)。结论:Dual-tDCS对大脑的神经调控作用可改善慢性期卒中患者运动和非运动相关脑区的FC,可能是慢性期脑卒中上肢运动功能障碍的康复机制。