Adopting the strategy of fuzzy control with self tuning factor within whole universe of discourse, a kind of fuzzy control method for jigger discharging is put forward. This method has many advantages over the convent...Adopting the strategy of fuzzy control with self tuning factor within whole universe of discourse, a kind of fuzzy control method for jigger discharging is put forward. This method has many advantages over the conventional PID controller in terms of response speed, stability and robustness. It is effective to restrain the jig bed from over thick or empty, and the stability of the bed is markedly improved. The good results are obtained in factory tests.展开更多
While renewable power generation and vehicle electrification are promising solutions to reduce greenhouse gas emissions, it faces great challenges to effectively integrate them in a power grid. The weather-dependent p...While renewable power generation and vehicle electrification are promising solutions to reduce greenhouse gas emissions, it faces great challenges to effectively integrate them in a power grid. The weather-dependent power generation of renewable energy sources, such as Photovoltaic (PV) arrays, could introduce significant intermittency to a power grid. Meanwhile, uncontrolled PEV charging may cause load surge in a power grid. This paper studies the optimization of PEV charging/discharging scheduling to reduce customer cost and improve grid performance. Optimization algorithms are developed for three cases: 1) minimize cost, 2) minimize power deviation from a pre-defined power profile, and 3) combine objective functions in 1) and 2). A Microgrid with PV arrays, bi-directional PEV charging stations, and a commercial building is used in this study. The bi-directional power from/to PEVs provides the opportunity of using PEVs to reduce the intermittency of PV power generation and the peak load of the Microgrid. Simulation has been performed for all three cases and the simulation results show that the presented optimization algorithms can meet defined objectives.展开更多
In this work,a series of experiments are carried out to investigate the effect of charge/discharge rates(1,2,3 and 4 C)and state of charges(SOCs,namely 0%,50%,75%and 100%)on thermal runaway(TR)and fire behavior of lit...In this work,a series of experiments are carried out to investigate the effect of charge/discharge rates(1,2,3 and 4 C)and state of charges(SOCs,namely 0%,50%,75%and 100%)on thermal runaway(TR)and fire behavior of lithium iron phosphate(LFP)batteries.The TR process caused by overheating LFP batteries is usually divided into four stages,with high temperatures and fire risks.High-rate charge and discharge damage the internal morphology and structural stability of materials seriously.The TR behavior of battery is fully aggravated,which is further manifested by the advanced opening of the safety vent,release of gas and occurrence of TR.With the increase of charging rate,the deteriorated TR characteristics can be discerned,such as the lower TR temperature,the shorter TR time,and the more serious TR consequences.Such changes can be assigned to the decline of battery stability.In addition,the battery SOC greatly impacts safety,especially the flame temperature and the severity of consequences.As for the 100%SOC battery cycled at 4 C,there is still a high risk of thermal runaway propagation at the position 1 m far away from the battery.This work helps to realize the TR and fire features of battery in-depth,enlightening the safety protection of battery.展开更多
Semiconductor electronic devices are prone to charge accumulation during production and transportation,which usually causes device breakdown.Ionizers are widely used for electrostatic elimination,and utilizing semicon...Semiconductor electronic devices are prone to charge accumulation during production and transportation,which usually causes device breakdown.Ionizers are widely used for electrostatic elimination,and utilizing semiconductor silicon for the discharge needle material in ionizers can effectively prevent metal contamination.To investigate the discharge characteristics of silicon needles and their mode modulation mechanism,this study has established an experimental platform for silicon needle-plate discharge under positive polarity voltage.Discharge pulse parameters and optical signals were measured at varying electrode spacings.The experimental results reveal that silicon needle discharge progresses through four regimes:the spontaneous streamer,the periodic streamer,the cluster streamer,and the glow discharge.Among these,the pulse amplitude is most uniform and stable in the periodic streamer regime.In addition,shorter-gap discharge exhibits higher pulse amplitude and repetition frequency but is easier to transition into the filament regime.The formation process of a single pulse is closely related to the field strength in the ionization region near the needle tip.Hence,parameters such as the pulse rising edge time and falling edge time show minimal variation with voltage.The amount of charge generated per unit time is primarily influenced by the repetition frequency.Consequently,the electrostatic ionizer produces the highest,most stable,and most uniform charges if it operates in the periodic streamer regime.展开更多
Fast-charging technology is indeed a critical technical problem for electric vehicles today.Improving the conductivity of electrode materials is one of the effective ways to solve this technical bottleneck.Here,we inc...Fast-charging technology is indeed a critical technical problem for electric vehicles today.Improving the conductivity of electrode materials is one of the effective ways to solve this technical bottleneck.Here,we incorporated highly conductive MXene and carbon nanotubes into the electrode materials of Li_(4)Ti_(5)O_(12)(LTO)and LiFePO_(4)(LFP)to construct the composite electrode material 3D-LTO-CNT-MXene and 3D-LFP-CNT-MXene(named 3D-LTO and 3D-LFP).The 3D-LTO we synthesized demonstrated an impressive capacity of 146.2 mAh g^(-1)at a 20C rate(where 1C=175 mA g^(-1)),the 3D-LFP material exhibited a capacity of 104.6 mAh g^(-1)at a 20C rate(where 1C=170 mA g^(-1)).This remarkable rate capability can be attributed to the constructed three-dimensional conductive network,which facilitates enhanced electrical conductivity and electron migration rates,thereby promoting rapid charging and discharging of the batteries.Furthermore,we assembled a 3D-LTO‖3D-LFP full cell,which demonstrated exceptional performance at a high rate of 10C(1C=170 mA g^(-1)),achieving an energy density of 68.34 Wh kg^(-1)and a power density of 1547.5 W kg^(-1).This work demonstrates the feasibility of constructing 3D highly conductive electrode materials for rapid charging and discharging at high rates.It paves the way for the commercial application of truly ultra-fast charging in electric vehicles.展开更多
Charge and discharge characteristics of Ni/MH batteries are investigated with experiments. During battery’s working, the voltage, capacity, temperature and internal resistance were recorded, corresponding curves were...Charge and discharge characteristics of Ni/MH batteries are investigated with experiments. During battery’s working, the voltage, capacity, temperature and internal resistance were recorded, corresponding curves were depicted. Variations of the aforementioned four parameters are differently obvious. Ending criteria of charge and discharge of Ni/MH batteries are discussed on the basis of the curves. Voltage, capacity and temperature of a battery can be used as ending criteria during charge. When discharge takes place, voltage, capacity and internal resistance can be chosen as ending criteria. As a whole, capacity is more suitable for being used as ending criteria of charge and discharge than the other three parameters. At last, the capacity of a battery is recommended to be ending criteria of charge and discharge. The conclusions will provide references to different capacity Ni/MH batteries for electric vehicles.展开更多
In this study, using a comprehensive numerical simulation of charge and discharge processes, we investigate the formation and evolution of negative charge and discharge characteristics of a grounded PMMA film irradiat...In this study, using a comprehensive numerical simulation of charge and discharge processes, we investigate the formation and evolution of negative charge and discharge characteristics of a grounded PMMA film irradiated by a non- focused electron beam. Electron scattering and transport processes in the sample are simulated with the Monte Carlo and the finite-different time-domain （FDTD） methods, respectively. The properties of charge and discharge processes are presented by the evolution of internal currents, charge quantity, surface potential, and discharge time. Internal charge accumulation in the sample may reach saturation by primary electron （PE） irradiation providing the charge duration is enough. Internal free electrons will run off to the ground in the form of leakage current due to charge diffusion and drift during the discharge process after irradiation, while trapped electrons remain. The negative surface potential determined by the charging quantity decreases to its saturation in the charge process, and then increases in the discharge process. A larger thickness of the PMMA film will result in greater charge amount and surface potential in charge saturation and in final discharge state, while the electron mobility of the material has little effects on the final discharge state. Moreover, discharge time is less for smaller thickness or larger electron mobility. The presented results can be helpful for estimating and weakening the charging of insulating samples especially under the intermittent electron beam irradiation in related surface analysis or measurement.展开更多
In an insulating system including solid and gas dielectrics, discharge type has a strong impact on charge accumulation at the interface between two dielectrics, and hence charge decay. In order to clarify the influenc...In an insulating system including solid and gas dielectrics, discharge type has a strong impact on charge accumulation at the interface between two dielectrics, and hence charge decay. In order to clarify the influence, a surface charge measurement system was constructed, and three types of discharge, i.e. surface discharge, and low intensity and high intensity coronas, were introduced to cause surface charge accumulation. The decay behavior of surface charges after different types of discharge was obtained at various temperatures. It was found that total surface charges monotonically decreased with time, and the decay rate became larger as temperature increased. However, after a surface discharge or a high intensity corona, surface charge density in the local area appeared to fluctuate during the decay process. Compared with this, the fluctuation of surface charge density was not observed after a low intensity corona. The mechanisms of surface charge accumulation and decay were analysed. Moreover, a microscopic physical model involving charge production, accumulation, and decay was proposed so that the experimental results could be explained.展开更多
Carbon-based electric double layer capacitors(EDLCs)hold tremendous potentials due to their high-power performance and excellent cycle stability.However,the practical use of EDLCs is limited by the low energy density ...Carbon-based electric double layer capacitors(EDLCs)hold tremendous potentials due to their high-power performance and excellent cycle stability.However,the practical use of EDLCs is limited by the low energy density in aqueous electrolyte and sluggish diffusion kinetics in organic or/and ionic liquids electrolyte.Herein,3D carbon frameworks(3DCFs)constructed by interconnected nanocages(10-20 nm)with an ultrathin wall of ca.2 nm have been fabricated,which possess high specific surface area,hierarchical porosity and good conductive network.After deoxidization,the deoxidized 3DCF(3DCFDO)exhibits a record low IR drop of 0.064 V at 100 A g^−1 and ultrafast charge/discharge rate up to 10 V s^−1.The related device can be charged up to 77.4%of its maximum capacitance in 0.65 s at 100 A g^−1 in 6 M KOH.It has been found that the 3DCF-DO has a great affinity to EMIMBF4,resulting in a high specific capacitance of 174 F g^−1 at 1 A g^−1,and a high energy density of 34 Wh kg^−1 at an ultrahigh power density of 150 kW kg^−1 at 4 V after a fast charge in 1.11 s.This work provides a facile fabrication of novel 3D carbon frameworks for supercapacitors with ultrafast charge/discharge rate and high energy-power density.展开更多
Using a unipolar pulse with the rise time and the pulse duration in the order of microsecond as the primary pulse, a nanosecond pulse with the repetitive frequency of several kilohertz is generated by a spark gap swit...Using a unipolar pulse with the rise time and the pulse duration in the order of microsecond as the primary pulse, a nanosecond pulse with the repetitive frequency of several kilohertz is generated by a spark gap switch. By varying both the inter-pulse duration and the pulse frequency, the voltage recovery rate of the spark gap switch is investigated at different working conditions such as the gas pressure, the gas composition as well as the bias voltage. The results reveal that either increase in gas pressure or addition of SF6 to the air can increase the voltage recovery rate. The effect of gas composition on the voltage recovery rate is discussed based on the transferring and distribution of the residual space charges. The repetitive nanosecond pulse source is also applied to the generation of large volume, and the discharge currents are measured to investigate the effect of pulse repetition rate on the large volume streamer discharge.展开更多
To investigate the effect of the rib structure on the discharge characteristics of the plasma display panel, the potential distribution, particles density distribution and ions incident angle distribution were examine...To investigate the effect of the rib structure on the discharge characteristics of the plasma display panel, the potential distribution, particles density distribution and ions incident angle distribution were examined by simulation of a two-dimensional particle-in-cell/Monte Carlo collision, with two kinds of rib structure： the stripe rib structure and the Waffle rib structure. The results showed that the distribution of electric potential at the corner of the discharge cell was almost the same for these two rib structures while in the centre there was a difference between these two rib structures. The striation phenomenon could be observed in both cases. The distribution of density also indicated that the striation phenomenon was accompanied by the firing of discharge, and the Waffle rib structure might reduce the density humps. In the cell with a stripe rib structure, the profiles of the surface charge density along the sustained dielectric layer presented a better fluctuating distribution than that in the cell with a Waffle rib structure. The spatial potential and particle density in the discharge bulk showed that the Waffle ribs could weaken the striation phenomenon, which could be explained by the decrease in the particle numbers in the discharge cell. The simulation results of the ion incident angle showed that most ions impacted the sustained dielectric layer in the normal stripe rib cell with an incident angle in the range of 6° to 19° while with the Waffle rib structure the incident angle of most ions was in the range of 4° to 19°. The Waffle rib structure did not affect the angle distribution of incident ions significantly.展开更多
The corona discharges provide an efficient way to induce precipitation or eliminate fog by increasing ion density in the open air.In this paper,one bipolar corona discharge array(positive and negative high voltage cou...The corona discharges provide an efficient way to induce precipitation or eliminate fog by increasing ion density in the open air.In this paper,one bipolar corona discharge array(positive and negative high voltage coupled simultaneously)which can generate high densities of positive and negative ions is developed.The comparison between bipolar corona discharge array and unipolar corona discharge array(positive or negative coupled only)indicates that bipolar corona discharge array can generate~3 times higher ion density than unipolar corona discharge array.More charged aerosols are produced through collisions between ions and aerosols.The collision rate between aerosols is increased substantially by the attractive forces between positively and negatively charged aerosols.The deposition of aerosols induced by bipolar discharges is 25.7%higher than that of unipolar discharges at the humidity super-saturation condition.Therefore,the bipolar corona discharge system is a new option for the large scale ion sources used for artificial weather modification.展开更多
Spherical Ni（OH）2 particles were prepared by an aqueous solution precipitation route. The structure of spherical Ni（OH）2 was investigated by scanning electron microscopy and transmission electron microscopy and co...Spherical Ni（OH）2 particles were prepared by an aqueous solution precipitation route. The structure of spherical Ni（OH）2 was investigated by scanning electron microscopy and transmission electron microscopy and compared with that of traditional Ni（OH）2. The results show that the spherical nickel hydroxide consists of （Ni（OH）2） spheres with a reticulate structure of platelet-like, which is almost arranged radially and the crystalline grains intervene and connect with each other to form a three-dimensional net. The spherical Ni（OH）2 particle is full of pores, crannies between cleave planes. It is supposed that this structure is beneficial to the structural stability for the spherical particles during the charge/discharge processes and can improve the cycle life of the electrode; the pores and the crannies in spherical particles can shorten the proton diffusion distance and speed its velocity, which may result in that the local polarization is lowered. The electrochemical performances of the spherical Ni（OH）2 are improved by enhancing the conducting properties of the crystalline lattice due to its quick proton diffusion.展开更多
Valve-regulated-lead-acid (VRLA) battery charging performed in high-temperature environments is extremely risky under overcharge conditions, and may lead to a subsequent thermal runaway. A new pressure-controlled char...Valve-regulated-lead-acid (VRLA) battery charging performed in high-temperature environments is extremely risky under overcharge conditions, and may lead to a subsequent thermal runaway. A new pressure-controlled charging method was adopted and the charging characteristics of the pressure-controlled VRLA battery in high-temperature environments were ex-perimentally studied. The concept was tested in a large temperature gradient to obtain more details about the effects of users' accustomed charging and discharging modes on battery capacity. The premature capacity loss (PCL) phenomenon under high temperature exposure was analyzed. The results showed that the capacity loss could be recovered by charging using a large current.展开更多
Theoretical study on the electronic structures and related properties of 2,2,6,6-tetramethyl- l-piperidinyloxy （TEMPO） and its cationic lipid derivates in the charge/discharge processes has been carried out using th...Theoretical study on the electronic structures and related properties of 2,2,6,6-tetramethyl- l-piperidinyloxy （TEMPO） and its cationic lipid derivates in the charge/discharge processes has been carried out using the density functional theory （DFT） at the （U）B3LYP/6-31G（d,p） or 6-31＋G（d,p） level. The changes and regularities of geometric and electronic properties of these compounds in the charge/discharge processes were revealed in detail. The compu- tational results show that the substitute group plays a very important role in the electronic structures and related properties of TEMPOs during the charge/discharge processes. It is very interesting to find that after getting an electron, TEMPO is more stable in singlet state but the lipid is more stable in triplet state. For TEMPO, both the charge and the discharge processes greatly influence the electronic properties of N and O atoms of the radical part. For the cationic lipid, the discharge process mainly influences the pyridinium head and the charge process mainly influences the free radical head. Moreover, the solvent effect plays an important role in some bond lengths and the charge population of the free radical head. In addition, the UV-Vis absorption spectra simulated using TDDFT at the 6-31G（d,p） with the experimental ones. of TEMPO and the lipid were calculated and or 6-31＋G（d,p） level, in satisfying agreement展开更多
Mechanochemical synthesis of α-MnO2 was carried out with KMnO4 and Mn(CH3COO)2 in 1:1 mole ratio. The electrochemical performance of MnO2 electrode was investigated by cyclic voltammograms and alternating current imp...Mechanochemical synthesis of α-MnO2 was carried out with KMnO4 and Mn(CH3COO)2 in 1:1 mole ratio. The electrochemical performance of MnO2 electrode was investigated by cyclic voltammograms and alternating current impedance. The charge-discharge process of MnO2 supercapacitor in 6 mol/L KOH was studied within 1.2 V at 200 mA/g, suggesting that it displays double-layer capacibility in low potential scope and pseudo-capacitance properties in high potential scope. It is found that Mn3O4, an electrochemical inert, mainly forms in the initial 40 charge-discharge cycles. During cycling, the pseudo-capacitance properties disappear and the discharge curves are close to ideal ones, indicating double-layer capability. The maximum capacitance of MnO2 electrode is as high as 416 F/g, and retains 240 F/g after 200 cycles. The equivalent series resistance increases from 17 to 41 Ω.展开更多
Dielectric barrier discharge(DBD) is widely investigated in order to obtain uniform low-temperature plasma.Many studies have proved that some barrier materials,especially electrets,can improve the uniformity of discha...Dielectric barrier discharge(DBD) is widely investigated in order to obtain uniform low-temperature plasma.Many studies have proved that some barrier materials,especially electrets,can improve the uniformity of discharge.It is regarded as an available way to get atmospheric pressure glow discharge(APGD).In this paper,discharge forms with 4 different barrier materials(alumina,quartz,PTFE and PET) are investigated,and the transition of discharge form depending on the air pressure are recorded to estimate the influence of barrier materials on discharge.By using electrets as barrier materials,homogeneous discharges can be obtained in a more wide pressure range.Under the same experimental conditions,discharges with electrets are more uniform or have larger uniform areas due to the storage and desorption of charges on the surface of electrets.The electrons deposited in the surface layer can be released on next half cycle when the polarity of the applied voltage changes,and provide a number of seed electrons,which makes the discharge more homogeneous.The capacitance and the permittivity of barrier materials have no effect on the discharge form directly.展开更多
The space charge behavior of a dielectric under HVDC is influenced by the charge trap energy distribution in it. Hence, we in- vestigated the charge trap distributions in several kinds of typical polymer materials usi...The space charge behavior of a dielectric under HVDC is influenced by the charge trap energy distribution in it. Hence, we in- vestigated the charge trap distributions in several kinds of typical polymer materials using thermally stimulated discharge (TSD) and photo-stimulated discharge (PSD) methods, respectively. The experimental results show that,there is a significant difference between the trap energy distributions obtained by the two methods, but the difference decreases with the increase of the melting point of polymers. This is attributed to the change of the trap center environment during TSD caused by the increasing movements of both main chains and branched chains in polymers. PSD method is more accurate for investigating charge trap distribution in dielectrics, especially for polymers with low melting points.展开更多
The electrical and thermal characterization of near-surface electrical discharge plasma driven by radio frequency voltage are investigated experimentally in this paper. The influences of operating pressure, electrode ...The electrical and thermal characterization of near-surface electrical discharge plasma driven by radio frequency voltage are investigated experimentally in this paper. The influences of operating pressure, electrode distance, and duty cycle on the discharge are studied. When pressure reaches 60 Ton. （1 Torr= 1.33322 x 102 Pa） the transition from diffuse glow mode to constricted mode occurs. With the operating pressure varying from 10 Tort to 60 Torr, the discharge energy calculated from the charge-voltage （Q-V） Lissajous figure decreases rapidly, while it remains unchanged between 60 Torr and 460 Torr. Under certain experimental conditions, there exists an optimized electrode distance （8 mm）. As the duty cycle of applied voltage increases, the voltage-current waveforms and Q-V Lissajous figures show no distinct changes.展开更多
Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than ...Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms） were observed, and the interaction between associated lightning discharges was analyzed. All these three pairs of associated lightning discharges were found to involve three or more charge regions （the ground was considered as a special charge region）. Moreover, at least one charge region involved two lightning discharges per pair of associated lightning discharges. Identified fl＇om electric field changes, the subsequent lightning discharges were suppressed by the prior lightning discharges. However, it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge. The third case provided evidence of this possibility. Together, the results suggested that, if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions, lightning accidents on the ground could be greatly reduced, on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.展开更多
文摘Adopting the strategy of fuzzy control with self tuning factor within whole universe of discourse, a kind of fuzzy control method for jigger discharging is put forward. This method has many advantages over the conventional PID controller in terms of response speed, stability and robustness. It is effective to restrain the jig bed from over thick or empty, and the stability of the bed is markedly improved. The good results are obtained in factory tests.
文摘While renewable power generation and vehicle electrification are promising solutions to reduce greenhouse gas emissions, it faces great challenges to effectively integrate them in a power grid. The weather-dependent power generation of renewable energy sources, such as Photovoltaic (PV) arrays, could introduce significant intermittency to a power grid. Meanwhile, uncontrolled PEV charging may cause load surge in a power grid. This paper studies the optimization of PEV charging/discharging scheduling to reduce customer cost and improve grid performance. Optimization algorithms are developed for three cases: 1) minimize cost, 2) minimize power deviation from a pre-defined power profile, and 3) combine objective functions in 1) and 2). A Microgrid with PV arrays, bi-directional PEV charging stations, and a commercial building is used in this study. The bi-directional power from/to PEVs provides the opportunity of using PEVs to reduce the intermittency of PV power generation and the peak load of the Microgrid. Simulation has been performed for all three cases and the simulation results show that the presented optimization algorithms can meet defined objectives.
基金supported by the National Key Research and Development Plan(2023YFC3009900)the National Natural Science Foundation of China(52104197,52272396,52474233)+3 种基金Hongkong Scholar Program(XJ2022022)Research Grants Council of the Hong Kong Special Administrative Region(City U11214221)Natural Science Foundation of the Jiangsu Higher Education Institutions(21KJB620001)the Open Fund of the State Key Laboratory of Fire Science(SKLFS)Program(HZ2022-KF04)。
文摘In this work,a series of experiments are carried out to investigate the effect of charge/discharge rates(1,2,3 and 4 C)and state of charges(SOCs,namely 0%,50%,75%and 100%)on thermal runaway(TR)and fire behavior of lithium iron phosphate(LFP)batteries.The TR process caused by overheating LFP batteries is usually divided into four stages,with high temperatures and fire risks.High-rate charge and discharge damage the internal morphology and structural stability of materials seriously.The TR behavior of battery is fully aggravated,which is further manifested by the advanced opening of the safety vent,release of gas and occurrence of TR.With the increase of charging rate,the deteriorated TR characteristics can be discerned,such as the lower TR temperature,the shorter TR time,and the more serious TR consequences.Such changes can be assigned to the decline of battery stability.In addition,the battery SOC greatly impacts safety,especially the flame temperature and the severity of consequences.As for the 100%SOC battery cycled at 4 C,there is still a high risk of thermal runaway propagation at the position 1 m far away from the battery.This work helps to realize the TR and fire features of battery in-depth,enlightening the safety protection of battery.
基金financially supported by Wuxi Yanping Electronic Technology Co.Ltd.
文摘Semiconductor electronic devices are prone to charge accumulation during production and transportation,which usually causes device breakdown.Ionizers are widely used for electrostatic elimination,and utilizing semiconductor silicon for the discharge needle material in ionizers can effectively prevent metal contamination.To investigate the discharge characteristics of silicon needles and their mode modulation mechanism,this study has established an experimental platform for silicon needle-plate discharge under positive polarity voltage.Discharge pulse parameters and optical signals were measured at varying electrode spacings.The experimental results reveal that silicon needle discharge progresses through four regimes:the spontaneous streamer,the periodic streamer,the cluster streamer,and the glow discharge.Among these,the pulse amplitude is most uniform and stable in the periodic streamer regime.In addition,shorter-gap discharge exhibits higher pulse amplitude and repetition frequency but is easier to transition into the filament regime.The formation process of a single pulse is closely related to the field strength in the ionization region near the needle tip.Hence,parameters such as the pulse rising edge time and falling edge time show minimal variation with voltage.The amount of charge generated per unit time is primarily influenced by the repetition frequency.Consequently,the electrostatic ionizer produces the highest,most stable,and most uniform charges if it operates in the periodic streamer regime.
基金supported by Xinjiang Uygur Autonomous Region Graduate Research Innovation Project (No.XJ2024G195)Xinjiang Key Research and Development Project (No.2021B01001-1)+2 种基金the National Natural Science Foundation of China (No.22169020)the Natural Science Foundation of University in Jiangsu province (No.22KJB150003)the National Natural Science Foundation of China (No.22309068)
文摘Fast-charging technology is indeed a critical technical problem for electric vehicles today.Improving the conductivity of electrode materials is one of the effective ways to solve this technical bottleneck.Here,we incorporated highly conductive MXene and carbon nanotubes into the electrode materials of Li_(4)Ti_(5)O_(12)(LTO)and LiFePO_(4)(LFP)to construct the composite electrode material 3D-LTO-CNT-MXene and 3D-LFP-CNT-MXene(named 3D-LTO and 3D-LFP).The 3D-LTO we synthesized demonstrated an impressive capacity of 146.2 mAh g^(-1)at a 20C rate(where 1C=175 mA g^(-1)),the 3D-LFP material exhibited a capacity of 104.6 mAh g^(-1)at a 20C rate(where 1C=170 mA g^(-1)).This remarkable rate capability can be attributed to the constructed three-dimensional conductive network,which facilitates enhanced electrical conductivity and electron migration rates,thereby promoting rapid charging and discharging of the batteries.Furthermore,we assembled a 3D-LTO‖3D-LFP full cell,which demonstrated exceptional performance at a high rate of 10C(1C=170 mA g^(-1)),achieving an energy density of 68.34 Wh kg^(-1)and a power density of 1547.5 W kg^(-1).This work demonstrates the feasibility of constructing 3D highly conductive electrode materials for rapid charging and discharging at high rates.It paves the way for the commercial application of truly ultra-fast charging in electric vehicles.
文摘Charge and discharge characteristics of Ni/MH batteries are investigated with experiments. During battery’s working, the voltage, capacity, temperature and internal resistance were recorded, corresponding curves were depicted. Variations of the aforementioned four parameters are differently obvious. Ending criteria of charge and discharge of Ni/MH batteries are discussed on the basis of the curves. Voltage, capacity and temperature of a battery can be used as ending criteria during charge. When discharge takes place, voltage, capacity and internal resistance can be chosen as ending criteria. As a whole, capacity is more suitable for being used as ending criteria of charge and discharge than the other three parameters. At last, the capacity of a battery is recommended to be ending criteria of charge and discharge. The conclusions will provide references to different capacity Ni/MH batteries for electric vehicles.
基金supported by the National Natural Science Foundation of China(Grant Nos.11175140 and 11004157)the Foundation of National Key Laboratory of Space Microwave Technology of China(Grant No.9140C530101130C53013)
文摘In this study, using a comprehensive numerical simulation of charge and discharge processes, we investigate the formation and evolution of negative charge and discharge characteristics of a grounded PMMA film irradiated by a non- focused electron beam. Electron scattering and transport processes in the sample are simulated with the Monte Carlo and the finite-different time-domain （FDTD） methods, respectively. The properties of charge and discharge processes are presented by the evolution of internal currents, charge quantity, surface potential, and discharge time. Internal charge accumulation in the sample may reach saturation by primary electron （PE） irradiation providing the charge duration is enough. Internal free electrons will run off to the ground in the form of leakage current due to charge diffusion and drift during the discharge process after irradiation, while trapped electrons remain. The negative surface potential determined by the charging quantity decreases to its saturation in the charge process, and then increases in the discharge process. A larger thickness of the PMMA film will result in greater charge amount and surface potential in charge saturation and in final discharge state, while the electron mobility of the material has little effects on the final discharge state. Moreover, discharge time is less for smaller thickness or larger electron mobility. The presented results can be helpful for estimating and weakening the charging of insulating samples especially under the intermittent electron beam irradiation in related surface analysis or measurement.
基金the financial support from National Natural Science Foundation of China (No. 51607128)Natural Science Foundation of Hubei Province (No. 2016CFB111)China Postdoctoral Science Foundation (No. 2016M602353)
文摘In an insulating system including solid and gas dielectrics, discharge type has a strong impact on charge accumulation at the interface between two dielectrics, and hence charge decay. In order to clarify the influence, a surface charge measurement system was constructed, and three types of discharge, i.e. surface discharge, and low intensity and high intensity coronas, were introduced to cause surface charge accumulation. The decay behavior of surface charges after different types of discharge was obtained at various temperatures. It was found that total surface charges monotonically decreased with time, and the decay rate became larger as temperature increased. However, after a surface discharge or a high intensity corona, surface charge density in the local area appeared to fluctuate during the decay process. Compared with this, the fluctuation of surface charge density was not observed after a low intensity corona. The mechanisms of surface charge accumulation and decay were analysed. Moreover, a microscopic physical model involving charge production, accumulation, and decay was proposed so that the experimental results could be explained.
基金the financial support from the National Natural Science Foundation of China(51672033,U1610255,U1703251).
文摘Carbon-based electric double layer capacitors(EDLCs)hold tremendous potentials due to their high-power performance and excellent cycle stability.However,the practical use of EDLCs is limited by the low energy density in aqueous electrolyte and sluggish diffusion kinetics in organic or/and ionic liquids electrolyte.Herein,3D carbon frameworks(3DCFs)constructed by interconnected nanocages(10-20 nm)with an ultrathin wall of ca.2 nm have been fabricated,which possess high specific surface area,hierarchical porosity and good conductive network.After deoxidization,the deoxidized 3DCF(3DCFDO)exhibits a record low IR drop of 0.064 V at 100 A g^−1 and ultrafast charge/discharge rate up to 10 V s^−1.The related device can be charged up to 77.4%of its maximum capacitance in 0.65 s at 100 A g^−1 in 6 M KOH.It has been found that the 3DCF-DO has a great affinity to EMIMBF4,resulting in a high specific capacitance of 174 F g^−1 at 1 A g^−1,and a high energy density of 34 Wh kg^−1 at an ultrahigh power density of 150 kW kg^−1 at 4 V after a fast charge in 1.11 s.This work provides a facile fabrication of novel 3D carbon frameworks for supercapacitors with ultrafast charge/discharge rate and high energy-power density.
基金National Natural Science Foundation of China(No.50477027)
文摘Using a unipolar pulse with the rise time and the pulse duration in the order of microsecond as the primary pulse, a nanosecond pulse with the repetitive frequency of several kilohertz is generated by a spark gap switch. By varying both the inter-pulse duration and the pulse frequency, the voltage recovery rate of the spark gap switch is investigated at different working conditions such as the gas pressure, the gas composition as well as the bias voltage. The results reveal that either increase in gas pressure or addition of SF6 to the air can increase the voltage recovery rate. The effect of gas composition on the voltage recovery rate is discussed based on the transferring and distribution of the residual space charges. The repetitive nanosecond pulse source is also applied to the generation of large volume, and the discharge currents are measured to investigate the effect of pulse repetition rate on the large volume streamer discharge.
文摘To investigate the effect of the rib structure on the discharge characteristics of the plasma display panel, the potential distribution, particles density distribution and ions incident angle distribution were examined by simulation of a two-dimensional particle-in-cell/Monte Carlo collision, with two kinds of rib structure： the stripe rib structure and the Waffle rib structure. The results showed that the distribution of electric potential at the corner of the discharge cell was almost the same for these two rib structures while in the centre there was a difference between these two rib structures. The striation phenomenon could be observed in both cases. The distribution of density also indicated that the striation phenomenon was accompanied by the firing of discharge, and the Waffle rib structure might reduce the density humps. In the cell with a stripe rib structure, the profiles of the surface charge density along the sustained dielectric layer presented a better fluctuating distribution than that in the cell with a Waffle rib structure. The spatial potential and particle density in the discharge bulk showed that the Waffle ribs could weaken the striation phenomenon, which could be explained by the decrease in the particle numbers in the discharge cell. The simulation results of the ion incident angle showed that most ions impacted the sustained dielectric layer in the normal stripe rib cell with an incident angle in the range of 6° to 19° while with the Waffle rib structure the incident angle of most ions was in the range of 4° to 19°. The Waffle rib structure did not affect the angle distribution of incident ions significantly.
基金supported by National Key Research and Development Plan of China(No.2016YFC0401001)。
文摘The corona discharges provide an efficient way to induce precipitation or eliminate fog by increasing ion density in the open air.In this paper,one bipolar corona discharge array(positive and negative high voltage coupled simultaneously)which can generate high densities of positive and negative ions is developed.The comparison between bipolar corona discharge array and unipolar corona discharge array(positive or negative coupled only)indicates that bipolar corona discharge array can generate~3 times higher ion density than unipolar corona discharge array.More charged aerosols are produced through collisions between ions and aerosols.The collision rate between aerosols is increased substantially by the attractive forces between positively and negatively charged aerosols.The deposition of aerosols induced by bipolar discharges is 25.7%higher than that of unipolar discharges at the humidity super-saturation condition.Therefore,the bipolar corona discharge system is a new option for the large scale ion sources used for artificial weather modification.
基金Project(50134020) supported by the National Natural Science Foundation of China
文摘Spherical Ni（OH）2 particles were prepared by an aqueous solution precipitation route. The structure of spherical Ni（OH）2 was investigated by scanning electron microscopy and transmission electron microscopy and compared with that of traditional Ni（OH）2. The results show that the spherical nickel hydroxide consists of （Ni（OH）2） spheres with a reticulate structure of platelet-like, which is almost arranged radially and the crystalline grains intervene and connect with each other to form a three-dimensional net. The spherical Ni（OH）2 particle is full of pores, crannies between cleave planes. It is supposed that this structure is beneficial to the structural stability for the spherical particles during the charge/discharge processes and can improve the cycle life of the electrode; the pores and the crannies in spherical particles can shorten the proton diffusion distance and speed its velocity, which may result in that the local polarization is lowered. The electrochemical performances of the spherical Ni（OH）2 are improved by enhancing the conducting properties of the crystalline lattice due to its quick proton diffusion.
文摘Valve-regulated-lead-acid (VRLA) battery charging performed in high-temperature environments is extremely risky under overcharge conditions, and may lead to a subsequent thermal runaway. A new pressure-controlled charging method was adopted and the charging characteristics of the pressure-controlled VRLA battery in high-temperature environments were ex-perimentally studied. The concept was tested in a large temperature gradient to obtain more details about the effects of users' accustomed charging and discharging modes on battery capacity. The premature capacity loss (PCL) phenomenon under high temperature exposure was analyzed. The results showed that the capacity loss could be recovered by charging using a large current.
文摘Theoretical study on the electronic structures and related properties of 2,2,6,6-tetramethyl- l-piperidinyloxy （TEMPO） and its cationic lipid derivates in the charge/discharge processes has been carried out using the density functional theory （DFT） at the （U）B3LYP/6-31G（d,p） or 6-31＋G（d,p） level. The changes and regularities of geometric and electronic properties of these compounds in the charge/discharge processes were revealed in detail. The compu- tational results show that the substitute group plays a very important role in the electronic structures and related properties of TEMPOs during the charge/discharge processes. It is very interesting to find that after getting an electron, TEMPO is more stable in singlet state but the lipid is more stable in triplet state. For TEMPO, both the charge and the discharge processes greatly influence the electronic properties of N and O atoms of the radical part. For the cationic lipid, the discharge process mainly influences the pyridinium head and the charge process mainly influences the free radical head. Moreover, the solvent effect plays an important role in some bond lengths and the charge population of the free radical head. In addition, the UV-Vis absorption spectra simulated using TDDFT at the 6-31G（d,p） with the experimental ones. of TEMPO and the lipid were calculated and or 6-31＋G（d,p） level, in satisfying agreement
文摘Mechanochemical synthesis of α-MnO2 was carried out with KMnO4 and Mn(CH3COO)2 in 1:1 mole ratio. The electrochemical performance of MnO2 electrode was investigated by cyclic voltammograms and alternating current impedance. The charge-discharge process of MnO2 supercapacitor in 6 mol/L KOH was studied within 1.2 V at 200 mA/g, suggesting that it displays double-layer capacibility in low potential scope and pseudo-capacitance properties in high potential scope. It is found that Mn3O4, an electrochemical inert, mainly forms in the initial 40 charge-discharge cycles. During cycling, the pseudo-capacitance properties disappear and the discharge curves are close to ideal ones, indicating double-layer capability. The maximum capacitance of MnO2 electrode is as high as 416 F/g, and retains 240 F/g after 200 cycles. The equivalent series resistance increases from 17 to 41 Ω.
基金Project Supported by National Natural Science Foundation of China(50537020,50507003)Specialized Research Fund for the Doc-toral Programof High Education of China(20050079006).
文摘Dielectric barrier discharge(DBD) is widely investigated in order to obtain uniform low-temperature plasma.Many studies have proved that some barrier materials,especially electrets,can improve the uniformity of discharge.It is regarded as an available way to get atmospheric pressure glow discharge(APGD).In this paper,discharge forms with 4 different barrier materials(alumina,quartz,PTFE and PET) are investigated,and the transition of discharge form depending on the air pressure are recorded to estimate the influence of barrier materials on discharge.By using electrets as barrier materials,homogeneous discharges can be obtained in a more wide pressure range.Under the same experimental conditions,discharges with electrets are more uniform or have larger uniform areas due to the storage and desorption of charges on the surface of electrets.The electrons deposited in the surface layer can be released on next half cycle when the polarity of the applied voltage changes,and provide a number of seed electrons,which makes the discharge more homogeneous.The capacitance and the permittivity of barrier materials have no effect on the discharge form directly.
基金Project supported by National Natural Science Foundation of China （51077101, 51277133）, National Basic Research Program of China （973 Program） （2009CB 724505）.
文摘The space charge behavior of a dielectric under HVDC is influenced by the charge trap energy distribution in it. Hence, we in- vestigated the charge trap distributions in several kinds of typical polymer materials using thermally stimulated discharge (TSD) and photo-stimulated discharge (PSD) methods, respectively. The experimental results show that,there is a significant difference between the trap energy distributions obtained by the two methods, but the difference decreases with the increase of the melting point of polymers. This is attributed to the change of the trap center environment during TSD caused by the increasing movements of both main chains and branched chains in polymers. PSD method is more accurate for investigating charge trap distribution in dielectrics, especially for polymers with low melting points.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11472306,51407197,and 51507187)
文摘The electrical and thermal characterization of near-surface electrical discharge plasma driven by radio frequency voltage are investigated experimentally in this paper. The influences of operating pressure, electrode distance, and duty cycle on the discharge are studied. When pressure reaches 60 Ton. （1 Torr= 1.33322 x 102 Pa） the transition from diffuse glow mode to constricted mode occurs. With the operating pressure varying from 10 Tort to 60 Torr, the discharge energy calculated from the charge-voltage （Q-V） Lissajous figure decreases rapidly, while it remains unchanged between 60 Torr and 460 Torr. Under certain experimental conditions, there exists an optimized electrode distance （8 mm）. As the duty cycle of applied voltage increases, the voltage-current waveforms and Q-V Lissajous figures show no distinct changes.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41075002, 41005022, and 40775004)
文摘Using a 3D lightning radiation source locating system （LLS）, three pairs of associated lightning discharges （two or more adjacent lightning discharges following an arbitrary rule that their space-gap was less than 10 km and their time-gap was less than 800 ms） were observed, and the interaction between associated lightning discharges was analyzed. All these three pairs of associated lightning discharges were found to involve three or more charge regions （the ground was considered as a special charge region）. Moreover, at least one charge region involved two lightning discharges per pair of associated lightning discharges. Identified fl＇om electric field changes, the subsequent lightning discharges were suppressed by the prior lightning discharges. However, it is possible that the prior lightning discharge provided a remaining discharge channel to facilitate the subsequent lightning discharge. The third case provided evidence of this possibility. Together, the results suggested that, if the charges in the main negative charge region can be consumed using artificial lightning above the main negative charge regions, lightning accidents on the ground could be greatly reduced, on the condition that the height of the main negative charge region and the charge intensity of the lower positive charge region are suitable.
