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Recent Developments of Modulation and Control for High-Power Current-Source-Converters Fed Electric Machine Systems 被引量:3
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作者 Pengcheng Liu Zheng Wang +2 位作者 Sanmin Wei Yuwen Bo Shaoning Pu 《CES Transactions on Electrical Machines and Systems》 CSCD 2020年第3期215-226,共12页
The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor a... The pulse-width-modulated(PWM)current-source converters(CSCs)fed electric machine systems can be considered as a type of high reliability energy conversion systems,since they work with the long-life DC-link inductor and offer high fault-tolerant capability for short-circuit faults.Besides,they provide motor friendly waveforms and four-quadrant operation ability.Therefore,they are suitable for high-power applications of fans,pumps,compressors and wind power generation.The purpose of this paper is to comprehensively review recent developments of key technologies on modulation and control of high-power(HP)PWM-CSC fed electric machines systems,including reduction of low-order current harmonics,suppression of inductor–capacitor(LC)resonance,mitigation of common-mode voltage(CMV)and control of modular PWM-CSC fed systems.In particular,recent work on the overlapping effects during commutation,LC resonance suppression under fault-tolerant operation and collaboration of modular PMW-CSCs are described.Both theoretical analysis and some results in simulations and experiments are presented.Finally,a brief discussion regarding the future trend of the HP CSC fed electric machines systems is presented. 展开更多
关键词 current source converter(CSC) high power(HP)applications electric machine system inductor–capacitor(LC)resonance low-order current harmonics common-mode voltage(CMV) MODULATION control
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An in-situ self-etching enabled high-power electrode for aqueous zinc-ion batteries
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作者 Shuang Hou Dingtao Ma +5 位作者 Yanyi Wang Kefeng Ouyang Sicheng Shen Hongwei Mi Lingzhi Zhao Peixin Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第1期399-408,I0009,共11页
Sluggish storage kinetics is considered as the main bottleneck of cathode materials for fast-charging aqueous zinc-ion batteries(AZIBs).In this report,we propose a novel in-situ self-etching strategy to unlock the Pal... Sluggish storage kinetics is considered as the main bottleneck of cathode materials for fast-charging aqueous zinc-ion batteries(AZIBs).In this report,we propose a novel in-situ self-etching strategy to unlock the Palm tree-like vanadium oxide/carbon nanofiber membrane(P-VO/C)as a robust freestanding electrode.Comprehensive investigations including the finite element simulation,in-situ X-ray diffraction,and in-situ electrochemical impedance spectroscopy disclosed it an electrochemically induced phase transformation mechanism from VO to layered Zn_(x)V_(2)O_5·nH_(2)O,as well as superior storage kinetics with ultrahigh pseudocapacitive contribution.As demonstrated,such electrode can remain a specific capacity of 285 mA h g^(-1)after 100 cycles at 1 A g^(-1),144.4 mA h g^(-1)after 1500 cycles at 30 A g^(-1),and even 97 mA h g^(-1)after 3000 cycles at 60 A g^(-1),respectively.Unexpectedly,an impressive power density of 78.9 kW kg^(-1)at the super-high current density of 100 A g^(-1)also can be achieved.Such design concept of in-situ self-etching free-standing electrode can provide a brand-new insight into extending the pseudocapacitive storage limit,so as to promote the development of high-power energy storage devices including but not limited to AZIBs. 展开更多
关键词 In-situ self-etching Free-standing electrode Pseudocapacitive storage high-power Zinc-ion batteries
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An open-end high-power microwave-induced fracturing system for hard rock 被引量:1
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作者 Xia-Ting Feng Jiuyu Zhang +4 位作者 Feng Lin Chengxiang Yang Shiping Li Tianyang Tong Xiangxin Su 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第12期3163-3172,共10页
Microwave pre-treatment is considered as a promising technique for alleviating cutter wear. This paper introduces a high-power microwave-induced fracturing system for hard rock. The test system consists of a high-powe... Microwave pre-treatment is considered as a promising technique for alleviating cutter wear. This paper introduces a high-power microwave-induced fracturing system for hard rock. The test system consists of a high-power microwave subsystem (100 kW), a true triaxial testing machine, a dynamic monitoring subsystem, and an electromagnetic shielding subsystem. It can realize rapid microwave-induced fracturing, intelligent tuning of impedance, dynamic feedback under strong microwave fields, and active control of microwave parameters by addressing the following issues: the instability and insecurity of the system, the discharge breakdown between coaxial lines during high-power microwave output, and a lack of feedback of rock-microwave response. In this study, microwave-induced surface and borehole fracturing tests under true triaxial stress were carried out. Experimental comparisons imply that high-power microwave irradiation can reduce the fracturing time of hard rock and that the fracture range (160 mm) of a 915-MHz microwave source is about three times that of 2.45 GHz. After microwave-induced borehole fracturing, many tensile cracks occur on the rock surface and in the borehole: the maximum reduction of the P-wave velocity is 12.8%. The test results show that a high-power microwave source of 915 MHz is more conducive to assisting mechanical rock breaking and destressing. The system can promote the development of microwave-assisted rock breaking equipment. 展开更多
关键词 Hard rock engineering high-power microwave Microwave intelligent fracturing Dynamic feedback True triaxial stress
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Impact of amplified spontaneous emission noise on the SRS threshold of high-power fiber amplifiers
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作者 刘伟 任帅 +1 位作者 马鹏飞 周朴 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期234-238,共5页
Impact of amplified spontaneous emission(ASE)noise on the stimulated Raman scattering(SRS)threshold of highpower fiber amplifiers is demonstrated numerically through a spectral evolution approach.The simulation result... Impact of amplified spontaneous emission(ASE)noise on the stimulated Raman scattering(SRS)threshold of highpower fiber amplifiers is demonstrated numerically through a spectral evolution approach.The simulation results confirm that ASE noise in the Raman wavelength band could reduce the SRS threshold of high-power fiber amplifiers significantly.As for ASE noise originated the main amplifier,it becomes stronger and reduces the SRS threshold at shorter operation wavelength below 1052 nm.As for ASE noise originated from the seed laser,it reduces the SRS threshold at different operation wavelength under the condition that the Raman ratio is over-90 dB in the seed laser.The theoretical method and results in this work could provide a well reference to extend the operation wavelength of high-power fiber lasers. 展开更多
关键词 high-power fiber amplifiers amplified spontaneous emission stimulated Raman scattering
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On the Mean Value of High-Powers of a Special Character Sum Modulo a Prime
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作者 Xiaodan Yuan Wenpeng Zhang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第7期943-953,共11页
In this paper,we use the elementary methods,the properties of Dirichlet character sums and the classical Gauss sums to study the estimation of the mean value of high-powers for a special character sum modulo a prime,a... In this paper,we use the elementary methods,the properties of Dirichlet character sums and the classical Gauss sums to study the estimation of the mean value of high-powers for a special character sum modulo a prime,and derive an exact computational formula.It can be conveniently programmed by the“Mathematica”software,by which we can get the exact results easily. 展开更多
关键词 Quadratic character the classical gauss sums the mean value of high-power computational formula
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On the functions of astrocyte-mediated neuronal slow inward currents 被引量:1
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作者 Balázs Pál 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第12期2602-2612,共11页
Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extra synaptic N-met hyl-D-aspartate receptors with the contribution of astrocytes.These events a... Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extra synaptic N-met hyl-D-aspartate receptors with the contribution of astrocytes.These events are significantly slower than the excitatory postsynaptic currents.Parameters of slow inward currents are determined by seve ral factors including the mechanisms of astrocytic activation and glutamate release,as well as the diffusion pathways from the release site towards the extra synaptic recepto rs.Astrocytes are stimulated by neuronal network activity,which in turn excite neurons,forming an astrocyte-neuron feedback loop.Mostly as a consequence of brain edema,astrocytic swelling can also induce slow inward currents under pathological conditions.There is a growing body of evidence on the roles of slow inward currents on a single neuron or local network level.These events often occur in synchro ny on neurons located in the same astrocytic domain.Besides synchronization of neuronal excitability,slow inward currents also set synaptic strength via eliciting timing-dependent synaptic plasticity.In addition,slow inward currents are also subject to non-synaptic plasticity triggered by long-la sting stimulation of the excitatory inputs.Of note,there might be important regionspecific differences in the roles and actions triggering slow inward currents.In greater networks,the pathophysiological roles of slow inward currents can be better understood than physiological ones.Slow inward currents are identified in the pathophysiological background of autism,as slow inward currents drive early hypersynchrony of the neural networks.Slow inward currents are significant contributors to paroxysmal depolarizational shifts/interictal spikes.These events are related to epilepsy,but also found in Alzheimer's disease,Parkinson's disease,and stroke,leading to the decline of cognitive functions.Events with features overlapping with slow inward currents(excitatory,N-methyl-Daspartate-receptor mediated currents with astrocytic contribution) as ischemic currents and spreading depolarization also have a well-known pathophysiological role in worsening consequences of stroke,traumatic brain injury,or epilepsy.One might assume that slow inward currents occurring with low frequency under physiological conditions might contribute to synaptic plasticity and memory formation.However,to state this,more experimental evidence from greater neuronal networks or the level of the individual is needed.In this review,I aimed to summarize findings on slow inward currents and to speculate on the potential functions of it. 展开更多
关键词 ASTROCYTE cortical spreading depolarization gliotransmission GLUTAMATE neural synchronization NMDA receptor paroxysmal depolarizational shift slow inward current
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Lift-Off Effect of Koch and Circular Differential Pickup Eddy Current Probes
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作者 Guolong Chen Zheng Cao +3 位作者 Shuaishuai Zhang Ji Wei Wei Gao Wuyin Jin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第2期283-293,共11页
A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspection of defects.However,the extent of the lift-off effect on differential probes,including differe... A flexible or planar eddy current probe with a differential structure can suppress the lift-off noise during the inspection of defects.However,the extent of the lift-off effect on differential probes,including different coil structures,varies.In this study,two planar eddy current probes with differential pickup structures and the same size,Koch and circular probes,were used to compare lift-off effects.The eddy current distributions of the probes perturbed by 0°and 90°cracks were obtained by finite element analysis.The analysis results show that the 90°crack can impede the eddy current induced by the Koch probe even further at relatively low lift-off distance.The peak-to-peak values of the signal output from the two probes were compared at different lift-off distances using finite element analysis and experimental methods.In addition,the effects of different frequencies on the lift-off were studied experimentally.The results show that the signal peak-to-peak value of the Koch probe for the inspection of cracks in 90°orientation is larger than that of the circular probe when the lift-off distance is smaller than 1.2 mm.In addition,the influence of the lift-off distance on the peak-to-peak signal value of the two probes was studied via normalization.This indicates that the influence becomes more evident with an increase in excitation frequency.This research discloses the lift-off effect of differential planar eddy current probes with different coil shapes and proves the detection merit of the Koch probe for 90°cracks at low lift-off distances. 展开更多
关键词 Eddy current testing Differential pickup probe Fractal Koch curve Flexible eddy current probe
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Optimization of total harmonic current distortion and torque pulsation reduction in high-power induction motors using genetic algorithms 被引量:1
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作者 Arash SAYYAH Mitra AFLAKI Alireza REZAZADEH 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第12期1741-1752,共12页
This paper presents a powerful application of genetic algorithm (GA) for the minimization of the total harmonic current distortion (THCD) in high-power induction motors fed by voltage source inverters, based on an... This paper presents a powerful application of genetic algorithm (GA) for the minimization of the total harmonic current distortion (THCD) in high-power induction motors fed by voltage source inverters, based on an approximate harmonic model. That is, having defined a desired fundamental output voltage, optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for the two cases of three and five switching instants in the first quarter period of pulse width modulation (PWM) waveform are presented. Presence of harmonics in the stator excitation leads to a pulsing-torque component. Considering the fact that if the pulsing-torques are at low frequencies, they can cause troublesome speed fluctuations, shaft fatigue, and unsatisfactory performance in the feedback control system, the 5th, 7th, 1 lth, and 13th current harmonics (in the case of five switching angles) are constrained at some pre-specified values, to mitigate the detrimental effects of low-frequency harmonics. At the same time, the THCD is optimized while the required fundamental output voltage is maintained. 展开更多
关键词 Induction motor Genetic algorithm (GA) OPTIMIZATION Pulse width modulation (PWM) Torque pulsation Totalharmonic current distortion (THCD)
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Evidence of guide field magnetic reconnection in flapping current sheets
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作者 YunTian Hou SuPing Duan +1 位作者 Lei Dai Chi Wang 《Earth and Planetary Physics》 EI CAS CSCD 2024年第4期650-658,共9页
Based on current sheet flapping motion on 27 August 2018 in the dusk flank magnetotail,as recorded by instruments aboard Magnetospheric Multiscale(MMS)spacecraft,we present the first study of guide field reconnection ... Based on current sheet flapping motion on 27 August 2018 in the dusk flank magnetotail,as recorded by instruments aboard Magnetospheric Multiscale(MMS)spacecraft,we present the first study of guide field reconnection observed in the flux rope embedded in kink-like flapping current sheets near the dusk-side flank of the magnetotail.Unlike more common magnetotail reconnections,which are symmetric,these asymmetric small-scale(λ_(i)~650 km)reconnections were found in the highly twisted current sheet when the direction normal to the sheet changes from the Z direction into the Y direction.The unique feature of this unusual reconnection is that the reconnection jets are along the Z direction-different from outflow in the X direction,which is the more usual situation.This vertical reconnection jet is parallel or antiparallel to the up-and-down motion of the tail’s current sheet.The normalized reconnection rate R is estimated to be~0.1.Our results indicate that such asymmetric reconnections can significantly enlarge current sheet flapping,with large oscillation amplitudes.This letter presents direct evidence of guide field reconnection in a highly twisted current sheet,characterized by enlarged current sheet flapping as a consequence of the reconnection outflow. 展开更多
关键词 magnetic reconnection MAGNETOTAIL current sheet
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Double-ring high-frequency common-mode switching oscillation current sensor for inverter-fed machine winding insulation monitoring
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作者 Lingqing Pan Xizhou Du +3 位作者 Xing Lei Ting Ye Dawei Xiang Hao Li 《Global Energy Interconnection》 EI CSCD 2024年第1期106-116,共11页
Insulation failure significantly contributes to the unpredictable shutdown of power equipment.Compared to the partial discharge and high-frequency(HF)injection methods,the HF common-mode(CM)leakage current method offe... Insulation failure significantly contributes to the unpredictable shutdown of power equipment.Compared to the partial discharge and high-frequency(HF)injection methods,the HF common-mode(CM)leakage current method offers a non-intrusive and highly sensitive alternative.However,the detection of HF CM currents is susceptible to interference from differential-mode(DM)currents,which exhibit high-amplitude and multifrequency components during normal operation.To address this challenge,this paper proposes a double-ring current sensor based on the principle of magnetic shielding for inverter-fed machine winding insulation monitoring.The inner ring harnesses the magnetic aggregation effect to isolate the DM current magnetic field,whereas the outer ring serves as the magnetic core of the Rogowski current sensor,enabling HF CM current monitoring.First,the magnetic field distributions of the CM and DM currents were analyzed.Then,a correlation between the sensor parameters and signal-to-noise ratio of the target HF CM current was established.Finally,an experimental study was conducted on a 3-kW PMSM for verification.The results indicate that the proposed double-ring HF CM sensor can effectively mitigate DM current interference.Compared to a single-ring sensor,a reduction of approximately 40%in the DM component was achieved,which significantly enhanced the precision of online insulation monitoring. 展开更多
关键词 Magnetic shielding Double-ring Common-mode current Maxwell simulation
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Research and exploration of direct current power supply and distribution systems for Antarctic research stations
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作者 WANG Lei 《Advances in Polar Science》 CSCD 2024年第2期228-237,共10页
The power supply and distribution systems for Antarctic research stations have special characteristics.In light of a worldwide trend toward a gradual increase in the application of renewable energy,an analysis was per... The power supply and distribution systems for Antarctic research stations have special characteristics.In light of a worldwide trend toward a gradual increase in the application of renewable energy,an analysis was performed to assess the feasibility of achieving a direct current power supply and distribution at Antarctic research stations by comparing the characteristics of direct current and alternating current electricity.Research was also performed on the status quo and future trends in direct current power supply and distribution systems in Antarctica research stations in combination with case studies. 展开更多
关键词 direct current alternating current renewable energy ANTARCTIC research station
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Numerical analysis for the free-boundary current reversal equilibrium in the AC plasma current operation in a tokamak
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作者 胡业民 王柳青 +2 位作者 白书航 于治 夏天阳 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第2期22-30,共9页
In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary eq... In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary equilibrium code is developed to investigate such advanced tokamak discharges with current reversal equilibrium configuration. The calculation results show that the reversal current equilibrium can maintain finite pressure and also has considerable effects on the position of the X-point and the magnetic separatrix shape, and hence also on the position of the strike point on the divertor plates, which is extremely useful for magnetic design, MHD stability analysis, and experimental data analysis etc. for the AC plasma current operation on tokamaks. 展开更多
关键词 current reversal equilibrium AC operation free-boundary equilibrium TOKAMAK
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Analysis of Sea Surface Temperature Cooling in Typhoon Events Passing the Kuroshio Current
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作者 HU Yuyi SHAO Weizeng +3 位作者 SHEN Wei ZUO Juncheng JIANG Tao HU Song 《Journal of Ocean University of China》 CAS CSCD 2024年第2期287-303,共17页
The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to s... The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately 0.93.The water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model simulation.Accordingly,the RMSE of the SST is 0.92℃ with a COR of approximately 0.99.As revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively high.The variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak SWH.Moreover,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio Current.The sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the ocean.The variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in May.Moreover,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current. 展开更多
关键词 typhoon wave sea surface temperature Kuroshio current
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Alternating current heating techniques for lithium-ion batteries in electric vehicles:Recent advances and perspectives
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作者 Xinrong Huang Jinhao Meng +5 位作者 Wei Jiang Wenjie Liu Kailong Liu Yipu Zhang Daniel-Ioan Stroe Remus Teodorescu 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第9期679-697,共19页
The significant decrease in battery performance at low temperatures is one of the critical challenges that electric vehicles(EVs)face,thereby affecting the penetration rate in cold regions.Alternating current(AC)heati... The significant decrease in battery performance at low temperatures is one of the critical challenges that electric vehicles(EVs)face,thereby affecting the penetration rate in cold regions.Alternating current(AC)heating has attracted widespread attention due to its low energy consumption and uniform heating advantages.This paper introduces the recent advances in AC heating from the perspective of practical EV applications.First,the performance degradation of EVs in low-temperature environments is introduced briefly.The concept of AC heating and its research methods are provided.Then,the effects of various AC heating methods on battery heating performance are reviewed.Based on existing studies,the main factors that affect AC heating performance are analyzed.Moreover,various heating circuits based on EVs are categorized,and their cost,size,complexity,efficiency,reliability,and heating rate are elaborated and compared.The evolution of AC heaters is presented,and the heaters used in brand vehicles are sorted out.Finally,the perspectives and challenges of AC heating are discussed.This paper can guide the selection of heater implementation methods and the optimization of heating effects for future EV applications. 展开更多
关键词 Lithium-ion battery Low temperature Alternating current heating HEATER Electric vehicle
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Influence of Current Density on the Photocatalytic Activity of Nd:TiO_(2) Coatings
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作者 施渊吉 ZHANG Zhen +2 位作者 DAI Yunzhong LI Jingxiao CHEN Zeyu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第1期32-38,共7页
The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on... The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current density.AFM results revealed that the roughness of the coatings increased with the increasing current density.Phase and composition analysis showed that the Nd:TiO_(2) coatings were mainly composed of anatase and rutile phase.And the anatase phase content has reached the maximum value at the current density of 250 m A/cm^(2).XPS results indicated that Ti2p spin-orbit components of the Nd:TiO_(2) coatings are shifted towards higher binding energy,compared with the pure TiO_(2) coating,suggesting that some of the Nd^(3+)ions are combined with TiO_(2) lattice and led to dislocation.Photocatalytic test showed that the photocatalytic activity of Nd:TiO_(2) coatings varied in the same pattern with the anatase content variation in Nd:TiO_(2) coatings.The photocatalytic experiment results show that the photocatalytic activity of Nd:TiO_(2) coatings can be greatly enhanced with moderate amount of Nd^(3+).However,excessive amount of Nd^(3+)does not have an effective impact on the photoctalytic activity improvement. 展开更多
关键词 PEO current density AFM XPS Nd:TiO_(2) PHOTOCATALYTIC
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Recent advances in design of hydrogen evolution reaction electrocatalysts at high current density:A review
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作者 Zhipeng Li Xiaobin Liu +5 位作者 Qingping Yu Xinyue Qu Jun Wan Zhenyu Xiao Jingqi Chi Lei Wang 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第8期33-60,共28页
The electrolysis of water powered by renewable energy sources offers a promising method of"green hydrogen"production,which is considered to be at the heart of future carbon-neutral energy systems.In the past... The electrolysis of water powered by renewable energy sources offers a promising method of"green hydrogen"production,which is considered to be at the heart of future carbon-neutral energy systems.In the past decades,researchers have reported a number of hydrogen evolution reaction(HER)electrocatalysts with activity comparable to that of commercial Pt/C,but most of them are tested within a small current density range,typically no more than 500 mA cm^(-2).To realize the industrial application of hydrogen production from water electrolysis,it is essential to develop high-efficiency HER electrocatalysts at high current density(HCD≥500 mA cm^(-2)).Nevertheless,it remains challenging and significant to rational design HCD electrocatalysts for HER.In this paper,the design strategy of HCD electrocatalysts is discussed,and some HCD electrocatalysts for HER are reviewed in seven categories(alloy,metal oxide,metal hydroxide,metal sulfide/selenide,metal nitride,metal phosphide and other derived electrocatalysts).At the end of this article,we also pro-pose some viewpoints and prospects for the future development and research directions of HCD electrocatalysts for HER. 展开更多
关键词 ELECTROCATALYST High current density Hydrogen evolution reaction Water electrolysis
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Plasma current tomography for HL-2A based on Bayesian inference
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作者 刘自结 王天博 +5 位作者 吴木泉 罗正平 王硕 孙腾飞 肖炳甲 李建刚 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第5期165-173,共9页
An accurate plasma current profile has irreplaceable value for the steady-state operation of the plasma.In this study,plasma current tomography based on Bayesian inference is applied to an HL-2A device and used to rec... An accurate plasma current profile has irreplaceable value for the steady-state operation of the plasma.In this study,plasma current tomography based on Bayesian inference is applied to an HL-2A device and used to reconstruct the plasma current profile.Two different Bayesian probability priors are tried,namely the Conditional Auto Regressive(CAR)prior and the Advanced Squared Exponential(ASE)kernel prior.Compared to the CAR prior,the ASE kernel prior adopts nonstationary hyperparameters and introduces the current profile of the reference discharge into the hyperparameters,which can make the shape of the current profile more flexible in space.The results indicate that the ASE prior couples more information,reduces the probability of unreasonable solutions,and achieves higher reconstruction accuracy. 展开更多
关键词 plasma current tomography Bayesian inference machine learning Gaussian distribution
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“Flow” Transcranial Direct Current Stimulation (tDCS) for Depression Treatment in a Primary Healthcare General Practice—An Open-Label Cohort Study Measuring Montgomery-Åsberg Depression Rating Scale (MADRS-S) Outcomes
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作者 Chris Griffiths Harmony Jiang +1 位作者 David Smart Azhar Zafar 《Open Journal of Psychiatry》 2024年第4期386-399,共14页
Background: Flow FL-100 is a transcranial direct current stimulation (tDCS) device self-administered by a patient at home in combination with a software application delivered wellbeing behaviour therapy training. tDCS... Background: Flow FL-100 is a transcranial direct current stimulation (tDCS) device self-administered by a patient at home in combination with a software application delivered wellbeing behaviour therapy training. tDCS has evidence of effectiveness in treating symptoms of depression. Purpose/Aim: This post marketing study evaluated the effect of Flow on depression for primary care general practice patients with depression symptoms. Methods: Open-label patient cohort design with no control group. Inclusion criteria were aged 18 years or over and reporting depression symptoms. Participants self-administered five 30 minute tDCS sessions per week for the first three weeks, and then 3 sessions per week following this. Three, six and ten week assessment with participant self-report measure: Montgomery- Åsberg Depression Rating Scale (MADRS-S). Results: MADRS-S remission rates were between 29% - 30% at three weeks, 33% - 34% at six-weeks and 50% at 10-weeks treatment. There was a significant improvement in MADRS-S with large effect sizes at all time points. Conclusions: Flow tDCS can be delivered through a primary healthcare general practice service and patients will choose to use. Flow tDCS provides an effective depression treatment in addition and as an alternative to antidepressants and psychotherapy. tDCS has evidence as an effective depression treatment, and the widespread availability of tDCS in primary care general practice should be considered. 展开更多
关键词 DEPRESSION Transcranial Direct current Stimulation Wellbeing General Practice
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Fault Estimation for a Class of Markov Jump Piecewise-Affine Systems: Current Feedback Based Iterative Learning Approach
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作者 Yanzheng Zhu Nuo Xu +2 位作者 Fen Wu Xinkai Chen Donghua Zhou 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第2期418-429,共12页
In this paper, the issues of stochastic stability analysis and fault estimation are investigated for a class of continuoustime Markov jump piecewise-affine(PWA) systems against actuator and sensor faults. Firstly, a n... In this paper, the issues of stochastic stability analysis and fault estimation are investigated for a class of continuoustime Markov jump piecewise-affine(PWA) systems against actuator and sensor faults. Firstly, a novel mode-dependent PWA iterative learning observer with current feedback is designed to estimate the system states and faults, simultaneously, which contains both the previous iteration information and the current feedback mechanism. The auxiliary feedback channel optimizes the response speed of the observer, therefore the estimation error would converge to zero rapidly. Then, sufficient conditions for stochastic stability with guaranteed performance are demonstrated for the estimation error system, and the equivalence relations between the system information and the estimated information can be established via iterative accumulating representation.Finally, two illustrative examples containing a class of tunnel diode circuit systems are presented to fully demonstrate the effectiveness and superiority of the proposed iterative learning observer with current feedback. 展开更多
关键词 current feedback fault estimation iterative learning observer Markov jump piecewise-affine system
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Revisiting aluminum current collector in lithium-ion batteries:Corrosion and countermeasures
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作者 Shanglin Yang Jinyan Zhong +1 位作者 Songmei Li Bin Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第2期610-634,I0014,共26页
With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary m... With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be disregarded.Therefore,it is necessary to conduct a comprehensive review in this field.In this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures.Firstly,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components.Furthermore,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating conditions.Subsequently,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail.Lastly and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs. 展开更多
关键词 Lithium-ion battery Aluminum current collector CORROSION Electrochemical performance ELECTROLYTE Protective layer
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