In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall ...In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall conditioning,long-lasting fully noninductive current and divertor heat/particle flux.The fully noninductive current is driven by pure radio frequency(RF)waves with a lower hybrid current drive power of 2.5 MW and electron cyclotron resonance heating of 1.4 MW.This is an excellent experimental platform on the timescale of hundreds of seconds for studying multiscale instabilities,electron-dominant transport and particle recycling(plasma-wall interactions)under weak collisionality.展开更多
Phase-change memory(PCM)has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems.However,a key challenge in harnessing the advantages of PCM devices is achieving h...Phase-change memory(PCM)has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems.However,a key challenge in harnessing the advantages of PCM devices is achieving high-speed operation of these devices at elevated temperatures,which is critical for the efficient processing and reliable storage of data at full capacity.Herein,we report a novel PCM device based on Ta-doped antimony telluride(Sb2Te),which exhibits both high-speed characteristics and excellent high-temperature characteristics,with an operation speed of 2 ns,endurance of >106 cycles,and reversible switching at 140℃.The high coordination number of Ta and the strong bonds between Ta and Sb/Te atoms contribute to the robustness of the amorphous structure,which improves the thermal stability.Furthermore,the small grains in the three-dimensional limit lead to an increased energy efficiency and a reduced risk of layer segregation,reducing the power consumption and improving the long-term endurance.Our findings for this new Ta-Sb2Te material system can facilitate the development of PCMs with improved performance and novel applications.展开更多
This study is to understand the impact of operating conditions, especially initial operation temperature (T<sub>ini</sub>) which is set in a high temperature range, on the temperature profile of the interf...This study is to understand the impact of operating conditions, especially initial operation temperature (T<sub>ini</sub>) which is set in a high temperature range, on the temperature profile of the interface between the polymer electrolyte membrane (PEM) and the catalyst layer at the cathode (i.e., the reaction surface) in a single cell of polymer electrolyte fuel cell (PEFC). A 1D multi-plate heat transfer model based on the temperature data of the separator measured using the thermograph in a power generation experiment was developed to evaluate the reaction surface temperature (T<sub>react</sub>). In addition, to validate the proposed heat transfer model, T<sub>react</sub> obtained from the model was compared with that from the 3D numerical simulation using CFD software COMSOL Multiphysics which solves the continuity equation, Brinkman equation, Maxwell-Stefan equation, Butler-Volmer equation as well as heat transfer equation. As a result, the temperature gap between the results obtained by 1D heat transfer model and those obtained by 3D numerical simulation is below approximately 0.5 K. The simulation results show the change in the molar concentration of O<sub>2</sub> and H<sub>2</sub>O from the inlet to the outlet is more even with the increase in T<sub>ini</sub> due to the lower performance of O<sub>2</sub> reduction reaction. The change in the current density from the inlet to the outlet is more even with the increase in T<sub>ini</sub> and the value of current density is smaller with the increase in T<sub>ini </sub>due to the increase in ohmic over-potential and concentration over-potential. It is revealed that the change in T<sub>react</sub> from the inlet to the outlet is more even with the increase in T<sub>ini</sub> irrespective of heat transfer model. This is because the generated heat from the power generation is lower with the increase in T<sub>ini </sub>due to the lower performance of O<sub>2</sub> reduction reaction.展开更多
The future of optoelectronics is directed towards small-area light sources,foremost being microLEDs.However,their use has been inhibited so far primarily due to fabrication and integration challenges,which impair effi...The future of optoelectronics is directed towards small-area light sources,foremost being microLEDs.However,their use has been inhibited so far primarily due to fabrication and integration challenges,which impair efficiency and yield.Recently,bottom-up nanostructures grown using selective area epitaxy have garnered attention as a solution to the aforementioned issues.Prof.Lan Fu et.al.have used this technique to demonstrate uniform p-i-n core-shell InGaAs/InP nanowire array light emitting diodes.The devices are capable of voltage and geometry-controlled multi-wavelength and high-speed operations.Their publication accentuates the wide capabilities of bottom-up nanostructures to resolve the difficulties of nanoscale optoelectronics.展开更多
This paper addresses the control design for automatic train operation of high-speed trains with protection constraints.A new resilient nonlinear gain-based feedback control approach is proposed,which is capable of gua...This paper addresses the control design for automatic train operation of high-speed trains with protection constraints.A new resilient nonlinear gain-based feedback control approach is proposed,which is capable of guaranteeing,under some proper non-restrictive initial conditions,the protection constraints control raised by the distance-to-go(moving authority)curve and automatic train protection in practice.A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains.The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability,no adaptations of unknown parameters,function approximation of unknown nonlinearities,and attenuation of external disturbances in the proposed control strategies.Finally,rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.展开更多
We present two protocols for the controlled remote implementation of quantum operations between three-party high-dimensional systems. Firstly, the controlled teleportation of an arbitrary unitary operation by bidirect...We present two protocols for the controlled remote implementation of quantum operations between three-party high-dimensional systems. Firstly, the controlled teleportation of an arbitrary unitary operation by bidirectional quantum state teleportaion (BQST) with high-dimensional systems is considered. Then, instead of using the BQST method, a protocol for controlled remote implementation of partially unknown operations belonging to some restricted sets in high-dimensional systems is proposed. It is shown that, in these protocols, if and only if the controller would like to help the sender with the remote operations, the controlled remote implementation of quantum operations for high-dimensional systems can be completed.展开更多
A novel high-κ~ A1203/HfO2/AI203 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibit...A novel high-κ~ A1203/HfO2/AI203 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibits excellent program-erasable characteristics. A large memory window of ~4 V, a small leakage current density of ~2 ×10-6 Acre-2 at a gate voltage of 7V, a high charge trapping density of 1.42 × 1013 cm-2 at a working vo]tage of 4-10 V and good retention characteristics are observed. Furthermore, the programming (△ VFB = 2.8 V at 10 V for 10μs) and erasing speeds (△VFB =-1.7 V at -10 V for 10μs) of the fabricated capacitor based on SiGe substrates are significantly improved as compared with counterparts reported earlier. It is concluded that the high-κ Al2O3/HfO2/Al2O3 nanolaminate charge trapping capacitor structure based on SiGe substrates is a promising candidate for future nano-scaled nonvolatile flash memory applications.展开更多
The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, ...The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.展开更多
High-speed trains linking Xi’an,capital of Northwest China’s Shaanxi Province,and southwestern metropolis Chengdu,capital of Sichuan Province,began operation on December 6,2017.The 658-km-long railway is China’s fi...High-speed trains linking Xi’an,capital of Northwest China’s Shaanxi Province,and southwestern metropolis Chengdu,capital of Sichuan Province,began operation on December 6,2017.The 658-km-long railway is China’s first high-speed rail to run through the Qinling Mountains,the dividing line of the country’s northern and southern regions.The展开更多
This paper describes the control software together with the operational hardware, which successfully realizes the operation of a new fully programmable imaging system with high spatial and temporal resolutions on the ...This paper describes the control software together with the operational hardware, which successfully realizes the operation of a new fully programmable imaging system with high spatial and temporal resolutions on the KT5D magnetic torus, for observing the visible l ight emission from the plasma discharge.展开更多
In this article,we derive the Lp-boundedness of the variation operators associated with the heat semigroup which is generated by the high order Schrodinger type operator(—Δ)^2+V%2 in R%n(n≥5)with V being a nonnegat...In this article,we derive the Lp-boundedness of the variation operators associated with the heat semigroup which is generated by the high order Schrodinger type operator(—Δ)^2+V%2 in R%n(n≥5)with V being a nonnegative potential satisfying the reverse Holder inequality.Furt her more,we prove the boundedness of the variation operators on associated Morrey spaces.In the proof of the main results,we always make use of the variation inequalities associated with the hea t semigroup genera ted by the biharmonic operator(-Δ)2.展开更多
Medical equipments related to life safety of human, it is important to detect by a high precise method. Image mosaic which based on Harris corner operator is a commonly used method in this area;Harris operator has low...Medical equipments related to life safety of human, it is important to detect by a high precise method. Image mosaic which based on Harris corner operator is a commonly used method in this area;Harris operator has low calculation burden, it is simple and stable, so it is more effective comparing with other feature point extracted operators. But in this algorithm, corner points can only be detected in a single-scale, there may be losing information of corner points, causing corner point location offset, extracting false corner points because of noise. In order to solve this question, the acquired images should be processed by dilation and erosion operation firstly, then do image mosaic. Results show that image noise can be eliminated effectively after those morphological processes, as well as the false positive noise generated by image glitch. The success rate of image mosaic and detection accuracy can be greatly improved through the Morphology-Harris operator. Measurement of precision instruments which based on this new method will improve the measurement accuracy, and the research in this area will promote the further development of machine vision technology.展开更多
The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even le...The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).展开更多
The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power...The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this paper,we discuss our design and demonstration of a water management strategy that supports high current and long cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water management approach is based on water vapor feeding in the hydrogen electrode,and water evaporation in the iron electrode,thus enabling the high current density operation of 300 mA cm^(-2).展开更多
Development of lead-free halide perovskites that are innocuous and stable has become an attractive trend in resistive random access memory(RRAM)fields.However,their inferior memory properties compared with the lead-ba...Development of lead-free halide perovskites that are innocuous and stable has become an attractive trend in resistive random access memory(RRAM)fields.However,their inferior memory properties compared with the lead-based analogs hinder their commercialization.Herein,the lead-free Cs_(3)Bi_(2)Br_(9)perovskite quantum dot(PQD)-based RRAMs are reported with outstanding memory performance,where Cs_(3)Bi_(2)Br_(9)quantum dots(QDs)are synthesized via a modified ligand-assisted recrystallization process.This is the first report of applying Cs_(3)Bi_(2)Br_(9)QDs as the switching layer for RRAM device.The Cs_(3)Bi_(2)Br_(9)QD device demonstrates nonvolatile resistive switching(RS)effect with large ON/OFF ratio of 105,low set voltage of-0.45 V,as well as good reliability,reproducibility,and flexibility.Concurrently,the device exhibits the notable tolerance toward moisture,heat and light illumination,and long-term stability of 200 days.More impressively,the device shows the reliable light-modulated RS behavior,and therefrom the logic gate operations including"AND"and"OR"are implemented,foreboding its prospect in logic circuits integrated with storage and computation.Such multifunctionality of device could be derived from the unique 2D layered crystal structure,small particle size,quantum confinement effect,and photoresponse of Cs_(3)Bi_(2)Br_(9)QDs.This work provides the strategy toward the high-performance RRAMs based on stable and eco-friendly perovskites for future applications.展开更多
基金the National Key R&D Program of China(No.2022YFE03010003)National Natural Science Foundation of China(No.12275309).
文摘In 2021,EAST realized a steady-state long pulse with a duration over 100 s and a core electron temperature over 10 keV.This is an integrated operation that resolves several key issues,including active control of wall conditioning,long-lasting fully noninductive current and divertor heat/particle flux.The fully noninductive current is driven by pure radio frequency(RF)waves with a lower hybrid current drive power of 2.5 MW and electron cyclotron resonance heating of 1.4 MW.This is an excellent experimental platform on the timescale of hundreds of seconds for studying multiscale instabilities,electron-dominant transport and particle recycling(plasma-wall interactions)under weak collisionality.
基金supported by the National Key Research and Development Program of China(2017YFA0206101,2017YFB0701703,2017YFA0206104,2017YFB0405601,2018YFB0407500)the National Natural Science Foundation of China(91964204,61874178,61874129)+1 种基金the Science and Technology Council of Shanghai(20501120300,18DZ2272800)the Shanghai Sailing Program(19YF1456100).
文摘Phase-change memory(PCM)has considerable promise for new applications based on von Neumann and emerging neuromorphic computing systems.However,a key challenge in harnessing the advantages of PCM devices is achieving high-speed operation of these devices at elevated temperatures,which is critical for the efficient processing and reliable storage of data at full capacity.Herein,we report a novel PCM device based on Ta-doped antimony telluride(Sb2Te),which exhibits both high-speed characteristics and excellent high-temperature characteristics,with an operation speed of 2 ns,endurance of >106 cycles,and reversible switching at 140℃.The high coordination number of Ta and the strong bonds between Ta and Sb/Te atoms contribute to the robustness of the amorphous structure,which improves the thermal stability.Furthermore,the small grains in the three-dimensional limit lead to an increased energy efficiency and a reduced risk of layer segregation,reducing the power consumption and improving the long-term endurance.Our findings for this new Ta-Sb2Te material system can facilitate the development of PCMs with improved performance and novel applications.
文摘This study is to understand the impact of operating conditions, especially initial operation temperature (T<sub>ini</sub>) which is set in a high temperature range, on the temperature profile of the interface between the polymer electrolyte membrane (PEM) and the catalyst layer at the cathode (i.e., the reaction surface) in a single cell of polymer electrolyte fuel cell (PEFC). A 1D multi-plate heat transfer model based on the temperature data of the separator measured using the thermograph in a power generation experiment was developed to evaluate the reaction surface temperature (T<sub>react</sub>). In addition, to validate the proposed heat transfer model, T<sub>react</sub> obtained from the model was compared with that from the 3D numerical simulation using CFD software COMSOL Multiphysics which solves the continuity equation, Brinkman equation, Maxwell-Stefan equation, Butler-Volmer equation as well as heat transfer equation. As a result, the temperature gap between the results obtained by 1D heat transfer model and those obtained by 3D numerical simulation is below approximately 0.5 K. The simulation results show the change in the molar concentration of O<sub>2</sub> and H<sub>2</sub>O from the inlet to the outlet is more even with the increase in T<sub>ini</sub> due to the lower performance of O<sub>2</sub> reduction reaction. The change in the current density from the inlet to the outlet is more even with the increase in T<sub>ini</sub> and the value of current density is smaller with the increase in T<sub>ini </sub>due to the increase in ohmic over-potential and concentration over-potential. It is revealed that the change in T<sub>react</sub> from the inlet to the outlet is more even with the increase in T<sub>ini</sub> irrespective of heat transfer model. This is because the generated heat from the power generation is lower with the increase in T<sub>ini </sub>due to the lower performance of O<sub>2</sub> reduction reaction.
文摘The future of optoelectronics is directed towards small-area light sources,foremost being microLEDs.However,their use has been inhibited so far primarily due to fabrication and integration challenges,which impair efficiency and yield.Recently,bottom-up nanostructures grown using selective area epitaxy have garnered attention as a solution to the aforementioned issues.Prof.Lan Fu et.al.have used this technique to demonstrate uniform p-i-n core-shell InGaAs/InP nanowire array light emitting diodes.The devices are capable of voltage and geometry-controlled multi-wavelength and high-speed operations.Their publication accentuates the wide capabilities of bottom-up nanostructures to resolve the difficulties of nanoscale optoelectronics.
基金supported jointly by the National Natural Science Foundation of China(61703033,61790573)Beijing Natural Science Foundation(4192046)+1 种基金Fundamental Research Funds for Central Universities(2018JBZ002)State Key Laboratory of Rail Traffic Control and Safety(RCS2018ZT013),Beijing Jiaotong University
文摘This paper addresses the control design for automatic train operation of high-speed trains with protection constraints.A new resilient nonlinear gain-based feedback control approach is proposed,which is capable of guaranteeing,under some proper non-restrictive initial conditions,the protection constraints control raised by the distance-to-go(moving authority)curve and automatic train protection in practice.A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains.The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability,no adaptations of unknown parameters,function approximation of unknown nonlinearities,and attenuation of external disturbances in the proposed control strategies.Finally,rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11074088)
文摘We present two protocols for the controlled remote implementation of quantum operations between three-party high-dimensional systems. Firstly, the controlled teleportation of an arbitrary unitary operation by bidirectional quantum state teleportaion (BQST) with high-dimensional systems is considered. Then, instead of using the BQST method, a protocol for controlled remote implementation of partially unknown operations belonging to some restricted sets in high-dimensional systems is proposed. It is shown that, in these protocols, if and only if the controller would like to help the sender with the remote operations, the controlled remote implementation of quantum operations for high-dimensional systems can be completed.
基金Supported by the National Science and Technology Major Project of China under Grant No 2013ZX02303007the National Key Research and Development Program of China under Grant No 2016YFA0301701the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2016112
文摘A novel high-κ~ A1203/HfO2/AI203 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibits excellent program-erasable characteristics. A large memory window of ~4 V, a small leakage current density of ~2 ×10-6 Acre-2 at a gate voltage of 7V, a high charge trapping density of 1.42 × 1013 cm-2 at a working vo]tage of 4-10 V and good retention characteristics are observed. Furthermore, the programming (△ VFB = 2.8 V at 10 V for 10μs) and erasing speeds (△VFB =-1.7 V at -10 V for 10μs) of the fabricated capacitor based on SiGe substrates are significantly improved as compared with counterparts reported earlier. It is concluded that the high-κ Al2O3/HfO2/Al2O3 nanolaminate charge trapping capacitor structure based on SiGe substrates is a promising candidate for future nano-scaled nonvolatile flash memory applications.
文摘The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.
基金The project supported by the Scientific Research Fund of the Education Bureau of Hunan Province under Grant No. 05B041, the Key Project of the Ministry of Education under Grant No. 206103, the China Postdoctoral Science Foundation under Grant No. 2005037695, National Natural Science Foundation of China under Grant Nos. 2001CB309310, 10325523, and 90203018, and the Natural Science Foundation of Hunan Province under Grant Nos. 04JJ3017 and 05JJ30012
文摘High-speed trains linking Xi’an,capital of Northwest China’s Shaanxi Province,and southwestern metropolis Chengdu,capital of Sichuan Province,began operation on December 6,2017.The 658-km-long railway is China’s first high-speed rail to run through the Qinling Mountains,the dividing line of the country’s northern and southern regions.The
基金The project supported by Chinese National Science Foundation (Nos. 10335060, 10235010) and Creative Project Grants of ChineseAcademy of Science
文摘This paper describes the control software together with the operational hardware, which successfully realizes the operation of a new fully programmable imaging system with high spatial and temporal resolutions on the KT5D magnetic torus, for observing the visible l ight emission from the plasma discharge.
基金supported by the National Natural Science Foundation of China(11701453)Fundamental Research Funds for the Central Universities(31020180QD05)+2 种基金The second author was supported by the National Natural Science Foundation of China(11971431,11401525)the Natural Science Foundation of Zhejiang Province(LY18A010006)and the first Class Discipline of Zhejiang-A(Zhejiang Gongshang University-Statistics).
文摘In this article,we derive the Lp-boundedness of the variation operators associated with the heat semigroup which is generated by the high order Schrodinger type operator(—Δ)^2+V%2 in R%n(n≥5)with V being a nonnegative potential satisfying the reverse Holder inequality.Furt her more,we prove the boundedness of the variation operators on associated Morrey spaces.In the proof of the main results,we always make use of the variation inequalities associated with the hea t semigroup genera ted by the biharmonic operator(-Δ)2.
文摘Medical equipments related to life safety of human, it is important to detect by a high precise method. Image mosaic which based on Harris corner operator is a commonly used method in this area;Harris operator has low calculation burden, it is simple and stable, so it is more effective comparing with other feature point extracted operators. But in this algorithm, corner points can only be detected in a single-scale, there may be losing information of corner points, causing corner point location offset, extracting false corner points because of noise. In order to solve this question, the acquired images should be processed by dilation and erosion operation firstly, then do image mosaic. Results show that image noise can be eliminated effectively after those morphological processes, as well as the false positive noise generated by image glitch. The success rate of image mosaic and detection accuracy can be greatly improved through the Morphology-Harris operator. Measurement of precision instruments which based on this new method will improve the measurement accuracy, and the research in this area will promote the further development of machine vision technology.
文摘The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).
基金support primarily from the U.S.Department of Energy Advanced Research Projects Agency-Energy 2015 OPEN program under Contract No.67995support by Energy Storage Materials Initiative(ESMI),which is a Laboratory Directed Research and Development Project at Pacific Northwest National Laboratory(PNNL).PNNL is a multiprogram national laboratory operated for the U.S.Department of Energy(DOE)by Battelle Memorial Institute under Contract no.DE-AC05-76RL01830.
文摘The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this paper,we discuss our design and demonstration of a water management strategy that supports high current and long cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water management approach is based on water vapor feeding in the hydrogen electrode,and water evaporation in the iron electrode,thus enabling the high current density operation of 300 mA cm^(-2).
基金supported by the National Natural Science Foundation of China(21374106)National Natural Science Foundation of China(11774318,12074347,and U1304212)National Key Research Program of China(2016YFA0200104).
文摘Development of lead-free halide perovskites that are innocuous and stable has become an attractive trend in resistive random access memory(RRAM)fields.However,their inferior memory properties compared with the lead-based analogs hinder their commercialization.Herein,the lead-free Cs_(3)Bi_(2)Br_(9)perovskite quantum dot(PQD)-based RRAMs are reported with outstanding memory performance,where Cs_(3)Bi_(2)Br_(9)quantum dots(QDs)are synthesized via a modified ligand-assisted recrystallization process.This is the first report of applying Cs_(3)Bi_(2)Br_(9)QDs as the switching layer for RRAM device.The Cs_(3)Bi_(2)Br_(9)QD device demonstrates nonvolatile resistive switching(RS)effect with large ON/OFF ratio of 105,low set voltage of-0.45 V,as well as good reliability,reproducibility,and flexibility.Concurrently,the device exhibits the notable tolerance toward moisture,heat and light illumination,and long-term stability of 200 days.More impressively,the device shows the reliable light-modulated RS behavior,and therefrom the logic gate operations including"AND"and"OR"are implemented,foreboding its prospect in logic circuits integrated with storage and computation.Such multifunctionality of device could be derived from the unique 2D layered crystal structure,small particle size,quantum confinement effect,and photoresponse of Cs_(3)Bi_(2)Br_(9)QDs.This work provides the strategy toward the high-performance RRAMs based on stable and eco-friendly perovskites for future applications.