At the EAST tokamak, the ion temperature(T_(i)) is observed to be clamped around 1.25 keV in electron cyclotron resonance(ECR)-heated plasmas, even at core electron temperatures up to 10 keV(depending on the ECR heati...At the EAST tokamak, the ion temperature(T_(i)) is observed to be clamped around 1.25 keV in electron cyclotron resonance(ECR)-heated plasmas, even at core electron temperatures up to 10 keV(depending on the ECR heating power and the plasma density). This clamping results from the lack of direct ion heating and high levels of turbulence-driven transport. Turbulent transport analysis shows that trapped electron mode and electron temperature gradient-driven modes are the most unstable modes in the core of ECR-heated H-mode plasmas. Nevertheless, recently it was found that the T_(i)/T_(e)ratio can increase further with the fraction of the neutral beam injection(NBI) power, which leads to a higher core ion temperature(Ti0). In NBI heating-dominant H-mode plasmas, the ion temperature gradient-driven modes become the most unstable modes.Furthermore, a strong and broad internal transport barrier(ITB) can form at the plasma core in high-power NBI-heated H-mode plasmas when the T_(i)/T_(e)ratio approaches ~1, which results in steep core Teand Tiprofiles, as well as a peaked neprofile. Power balance analysis shows a weaker Teprofile stiffness after the formation of ITBs in the core plasma region, where Ticlamping is broken,and the core Tican increase further above 2 keV, which is 80% higher than the value of Ticlamping in ECR-heated plasmas. This finding proposes a possible solution to the problem of Ticlamping on EAST and demonstrates an advanced operational regime with the formation of a strong and broad ITB for future fusion plasmas dominated by electron heating.展开更多
Carbon capture and storage(CCS)technology is an imperative,strategic,and constitutive method to considerably reduce anthropogenic CO_(2)emissions and alleviate climate change issues.The ocean is the largest active car...Carbon capture and storage(CCS)technology is an imperative,strategic,and constitutive method to considerably reduce anthropogenic CO_(2)emissions and alleviate climate change issues.The ocean is the largest active carbon bank and an essential energy source on the Earth's surface.Compared to oceanic nature-based carbon dioxide removal(CDR),carbon capture from point sources with ocean storage is more appropriate for solving short-term climate change problems.This review focuses on the recent state-of-the-art developments in offshore carbon storage.It first discusses the current status and development prospects of CCS,associated with the chailenges and uncertainties of oceanic nature-based CDR.The second section outlines the mechanisms,sites,advantages,and ecologic hazards of direct offshore CO_(2)injection.The third section emphasizes the mechanisms,schemes,influencing factors,and recovery efficiency of ocean-based CO-CH_(4)replacement and CO_(2)-enhanced oil recovery are reviewed.In addition,this review discusses the economic aspects of offshore CCS and the preponderance of offshore CCs hubs.Finally,the upsides,limitations,and prospects for further investigation of offshore CO_(2)storage are presented.展开更多
Dielectric capacitors have a high power density,and are widely used in military and civilian life.The main problem lies in the serious deterioration of dielectric insulation performance at high temperatures.In this st...Dielectric capacitors have a high power density,and are widely used in military and civilian life.The main problem lies in the serious deterioration of dielectric insulation performance at high temperatures.In this study,a polycarbonate(PC)-based energy storage dielectric was designed with BN/SiO_(2)heterojunctions on its surface.Based on this structural design,a synergistic suppression of the carrier injection and transport was achieved,significantly improving the insulating properties of the polymer film.In particular,the composite film achieves optimal high-temperature energy-storage properties.The composite film can withstand an electric field intensity of 760 MV m^(-1)at 100℃and obtain an energy storage density of 8.32 J cm^(-3),while achieving a breakthrough energy storage performance even at 150℃(610 MV m^(-1),5.22 J cm^(-3)).Through adjustment of the heterojunction structure,free adjustment of the insulation performance of the material can be realized;this is of great significance for the optimization of the material properties.展开更多
A transient numerical model was established to predict the dispersion,distribution,and circulation behavior of the powder injected through the up snorkel in a Ruhrstahl–Heraeus(RH)degasser.The effects of the powder d...A transient numerical model was established to predict the dispersion,distribution,and circulation behavior of the powder injected through the up snorkel in a Ruhrstahl–Heraeus(RH)degasser.The effects of the powder diameter,the lifting gas flow rate,and the powder injection rate on the powder transport were investigated.Local powder concentration was measured by a cold model.The results showed that the predicted powder concentration agreed well with the measured.The powder injection process is divided into three periods,named dispersion period,aggregation and circulation period,and dynamically stable period according to the powder transport behavior.The powder diameter has a great effect on the particle dispersion.When the particles size changes from 30 to 500μm,the powder dispersion characteristic index changes from 0.110 to 0.741,and the ladle top zone powder mass ratio changes from 0.118 to 0.685.The powder circulation mass flow rate increases to 101.0 kg min^(-1)(150μm)and then decreases to 46.6 kg min^(-1)(500μm).Powders with a diameter of more than 220μm can change the steel flow mode in the RH degasser.Increasing the lifting gas flow could slightly improve the powder dispersion.Variation in the powder injection rate has almost no effect on the powder dispersion.展开更多
The spin relaxation time is long in organic semiconductors because of the weak spin-orbit and hyperfine interactions,leading to intensive study on spin transport in organic semiconductors.The rapid progress towards ut...The spin relaxation time is long in organic semiconductors because of the weak spin-orbit and hyperfine interactions,leading to intensive study on spin transport in organic semiconductors.The rapid progress towards utilizing spin degree of freedom in organic electronic devices is occurring.While the spin injection,transport and detection in organic semiconductors are demonstrated,the fundamental physics of these phenomena remains unclear.This paper highlights recent progress that has been made,focusing primarily on present experimental work.展开更多
Considering the special carriers in organic semiconductors, the spin polarized current under electric field in a ferromagnetic/organic semiconductor system is theoretically studied. Based on the spin-diffusion theory,...Considering the special carriers in organic semiconductors, the spin polarized current under electric field in a ferromagnetic/organic semiconductor system is theoretically studied. Based on the spin-diffusion theory, the current spin polarization under the electric field is obtained. It is found that electric field can enhance the current spin polarization.展开更多
The deposition profile of the impurity pellet is measured by a two-dimensional fast- framing vacuum ultraviolet （VUV） camera system in the large helical device （LHD）. The fast framing camera selectively measures t...The deposition profile of the impurity pellet is measured by a two-dimensional fast- framing vacuum ultraviolet （VUV） camera system in the large helical device （LHD）. The fast framing camera selectively measures the emission from the hydrogen-like ions of carbon （C VI） with a frame rate of several kHz. From the emission profile of the hydrogen-like carbon ions, which are in the process of ionization, the initial deposition profile of the carbon is estimated using a simple one-dimensional transport model.展开更多
This paper describes a radioactive tracer experiment carried out at the landward spoil site of the North Passage in the Yangtze Estuary in June, 1991. Scandium -46 was selected as the tracer, the total activity releas...This paper describes a radioactive tracer experiment carried out at the landward spoil site of the North Passage in the Yangtze Estuary in June, 1991. Scandium -46 was selected as the tracer, the total activity released was 179.45 GBq and the amount of the Sandium-46 glass was 495 g. The purpose of the experiment was to determine the sediment movement direction, path, velocity and transport rate, and therefore, to provide direct evidence for using the landward spoil site in the future. The experimental results showed that the sediment movement was governed by the ebb tide current during the period of mean and neap tides when the radioactive tracer was injected both on the flood and ebb tides, and the sediment moved from the release point to the middle of the North Passage near navigation buoy No. 269. The direciton of the sediment movement was 110 ° , the particle velocity was 758 m/d, and the sediment transport rate per unit width was 47.8 m3 / md.展开更多
The dynamical processes of the electric charge injection and transport from a metal electrode to the copolymer are investigated by using a nonadiabatic dynamic approach. The simulations are performed within the framew...The dynamical processes of the electric charge injection and transport from a metal electrode to the copolymer are investigated by using a nonadiabatic dynamic approach. The simulations are performed within the framework of an extended version of the one-dimensional Su-Schrieffer-Heeger （SSH） tight-binding model. It is found that the electric charge can be injected into the copolymer by increasing the applied voltage. For different structures of the copolymer, the critical voltage biases are different and the motion of the injected electric charge in the copolymer varies obviously. For the copolymer with a barrier-well-barrier configuration, the injected electric charge forms a wave packet due to the strong electron-lattice interaction in the barrier, then comes into the well and will be confined in it under a weak electric field. Under a medium electric field, the electric charge can go across the interface of two homopolymers and enter into the other potential barrier. For the copolymer with a well-barrier-well configuration, only under strong enough electric field can the electric charge transfer from the potential well into the barrier and ultimately reach a dynamic balance.展开更多
Carbon-based spintronics refers mainly to the spin injection and transport in carbon materials including carbon nanotubes,graphene,fullerene,and organic materials.In the last decade,extraordinary development has been ...Carbon-based spintronics refers mainly to the spin injection and transport in carbon materials including carbon nanotubes,graphene,fullerene,and organic materials.In the last decade,extraordinary development has been achieved for carbon-based spintronics,and the spin transport has been studied in both local and nonlocal spin valve devices.A series of theoretical and experimental studies have been done to reveal the spin relaxation mechanisms and spin transport properties in carbon materials,mostly for graphene and carbon nanotubes.In this article,we provide a brief review on spin injection and transport in graphene,carbon nanotubes,fullerene and organic thin films.展开更多
基金supported by National Natural Science Foundation of China(No.12135015)the Users with Excellence Program of Hefei Science Center,CAS(No.2021HSCUE012)+3 种基金the National Key R&D Program of China(No.2022Y FE03010003)the Major Science and Technology Infrastructure Maintenance and Reconstruction Projects of the Chinese Academy of Sciences 2021the Special Funds for Improving Conditions for Scientific Research in National Scientific Institutions 2022the China Scholarship Council。
文摘At the EAST tokamak, the ion temperature(T_(i)) is observed to be clamped around 1.25 keV in electron cyclotron resonance(ECR)-heated plasmas, even at core electron temperatures up to 10 keV(depending on the ECR heating power and the plasma density). This clamping results from the lack of direct ion heating and high levels of turbulence-driven transport. Turbulent transport analysis shows that trapped electron mode and electron temperature gradient-driven modes are the most unstable modes in the core of ECR-heated H-mode plasmas. Nevertheless, recently it was found that the T_(i)/T_(e)ratio can increase further with the fraction of the neutral beam injection(NBI) power, which leads to a higher core ion temperature(Ti0). In NBI heating-dominant H-mode plasmas, the ion temperature gradient-driven modes become the most unstable modes.Furthermore, a strong and broad internal transport barrier(ITB) can form at the plasma core in high-power NBI-heated H-mode plasmas when the T_(i)/T_(e)ratio approaches ~1, which results in steep core Teand Tiprofiles, as well as a peaked neprofile. Power balance analysis shows a weaker Teprofile stiffness after the formation of ITBs in the core plasma region, where Ticlamping is broken,and the core Tican increase further above 2 keV, which is 80% higher than the value of Ticlamping in ECR-heated plasmas. This finding proposes a possible solution to the problem of Ticlamping on EAST and demonstrates an advanced operational regime with the formation of a strong and broad ITB for future fusion plasmas dominated by electron heating.
基金the financial support from the Science and Technology Commission of Shanghai Municipality(No.21DZ1206200)the Shanghai Agriculture Science and Technology Program(No.2022-02-08-00-12-F01176)the financial support from the National Natural Science Foundation of China(Nos.52006135 and 72140008),respectively.
文摘Carbon capture and storage(CCS)technology is an imperative,strategic,and constitutive method to considerably reduce anthropogenic CO_(2)emissions and alleviate climate change issues.The ocean is the largest active carbon bank and an essential energy source on the Earth's surface.Compared to oceanic nature-based carbon dioxide removal(CDR),carbon capture from point sources with ocean storage is more appropriate for solving short-term climate change problems.This review focuses on the recent state-of-the-art developments in offshore carbon storage.It first discusses the current status and development prospects of CCS,associated with the chailenges and uncertainties of oceanic nature-based CDR.The second section outlines the mechanisms,sites,advantages,and ecologic hazards of direct offshore CO_(2)injection.The third section emphasizes the mechanisms,schemes,influencing factors,and recovery efficiency of ocean-based CO-CH_(4)replacement and CO_(2)-enhanced oil recovery are reviewed.In addition,this review discusses the economic aspects of offshore CCS and the preponderance of offshore CCs hubs.Finally,the upsides,limitations,and prospects for further investigation of offshore CO_(2)storage are presented.
基金This research was funded by the National Natural Science Foundation of China(No.U20A20308,52177017,and 51977050)Natural Science Foundation of Heilongjiang Province of China(No.YQ2021E036 and ZD2020E009)+3 种基金China Postdoctoral Science Foundation(No.2020T130156)Heilongjiang Postdoctoral Financial Assistance(No.LBHZ18098)Fundamental Research Foundation for Universities of Heilongjiang Province(No.2019-KYYWF-0207 and 2018-KYYWF-1624)University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2020177).
文摘Dielectric capacitors have a high power density,and are widely used in military and civilian life.The main problem lies in the serious deterioration of dielectric insulation performance at high temperatures.In this study,a polycarbonate(PC)-based energy storage dielectric was designed with BN/SiO_(2)heterojunctions on its surface.Based on this structural design,a synergistic suppression of the carrier injection and transport was achieved,significantly improving the insulating properties of the polymer film.In particular,the composite film achieves optimal high-temperature energy-storage properties.The composite film can withstand an electric field intensity of 760 MV m^(-1)at 100℃and obtain an energy storage density of 8.32 J cm^(-3),while achieving a breakthrough energy storage performance even at 150℃(610 MV m^(-1),5.22 J cm^(-3)).Through adjustment of the heterojunction structure,free adjustment of the insulation performance of the material can be realized;this is of great significance for the optimization of the material properties.
基金supported by the National Natural Science Foundation of China(Grant No.U20A20272)the Fundamental Research Funds for the Central Universities,NEU(No.N2025017).
文摘A transient numerical model was established to predict the dispersion,distribution,and circulation behavior of the powder injected through the up snorkel in a Ruhrstahl–Heraeus(RH)degasser.The effects of the powder diameter,the lifting gas flow rate,and the powder injection rate on the powder transport were investigated.Local powder concentration was measured by a cold model.The results showed that the predicted powder concentration agreed well with the measured.The powder injection process is divided into three periods,named dispersion period,aggregation and circulation period,and dynamically stable period according to the powder transport behavior.The powder diameter has a great effect on the particle dispersion.When the particles size changes from 30 to 500μm,the powder dispersion characteristic index changes from 0.110 to 0.741,and the ladle top zone powder mass ratio changes from 0.118 to 0.685.The powder circulation mass flow rate increases to 101.0 kg min^(-1)(150μm)and then decreases to 46.6 kg min^(-1)(500μm).Powders with a diameter of more than 220μm can change the steel flow mode in the RH degasser.Increasing the lifting gas flow could slightly improve the powder dispersion.Variation in the powder injection rate has almost no effect on the powder dispersion.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10974084,11222435 and 11023002)the National Basic Research Program of China (Grant Nos. 2010CB923402 and 2013CB922103)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities
文摘The spin relaxation time is long in organic semiconductors because of the weak spin-orbit and hyperfine interactions,leading to intensive study on spin transport in organic semiconductors.The rapid progress towards utilizing spin degree of freedom in organic electronic devices is occurring.While the spin injection,transport and detection in organic semiconductors are demonstrated,the fundamental physics of these phenomena remains unclear.This paper highlights recent progress that has been made,focusing primarily on present experimental work.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10574082 and 10474056, and the Natural Science Foundation of Shandong Province under Grant No Z2005A01.
文摘Considering the special carriers in organic semiconductors, the spin polarized current under electric field in a ferromagnetic/organic semiconductor system is theoretically studied. Based on the spin-diffusion theory, the current spin polarization under the electric field is obtained. It is found that electric field can enhance the current spin polarization.
基金supported by the NIFS budget code ULPP021,the Ministry of Education Science,Sports and CultureGrant-in-Aid for Scientific Research(B)23340184partially supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics(No.11261140328)
文摘The deposition profile of the impurity pellet is measured by a two-dimensional fast- framing vacuum ultraviolet （VUV） camera system in the large helical device （LHD）. The fast framing camera selectively measures the emission from the hydrogen-like ions of carbon （C VI） with a frame rate of several kHz. From the emission profile of the hydrogen-like carbon ions, which are in the process of ionization, the initial deposition profile of the carbon is estimated using a simple one-dimensional transport model.
文摘This paper describes a radioactive tracer experiment carried out at the landward spoil site of the North Passage in the Yangtze Estuary in June, 1991. Scandium -46 was selected as the tracer, the total activity released was 179.45 GBq and the amount of the Sandium-46 glass was 495 g. The purpose of the experiment was to determine the sediment movement direction, path, velocity and transport rate, and therefore, to provide direct evidence for using the landward spoil site in the future. The experimental results showed that the sediment movement was governed by the ebb tide current during the period of mean and neap tides when the radioactive tracer was injected both on the flood and ebb tides, and the sediment moved from the release point to the middle of the North Passage near navigation buoy No. 269. The direciton of the sediment movement was 110 ° , the particle velocity was 758 m/d, and the sediment transport rate per unit width was 47.8 m3 / md.
基金supported by the National Basic Research Program of China(Grant No.2009CB929204)the National Natural Science Foundation of China(Grant No.11074146)+1 种基金the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2010AM037 and ZR2010AM026)the Independent Innovation Foundation of Shandong University,China(Grant No.2009TS097)
文摘The dynamical processes of the electric charge injection and transport from a metal electrode to the copolymer are investigated by using a nonadiabatic dynamic approach. The simulations are performed within the framework of an extended version of the one-dimensional Su-Schrieffer-Heeger （SSH） tight-binding model. It is found that the electric charge can be injected into the copolymer by increasing the applied voltage. For different structures of the copolymer, the critical voltage biases are different and the motion of the injected electric charge in the copolymer varies obviously. For the copolymer with a barrier-well-barrier configuration, the injected electric charge forms a wave packet due to the strong electron-lattice interaction in the barrier, then comes into the well and will be confined in it under a weak electric field. Under a medium electric field, the electric charge can go across the interface of two homopolymers and enter into the other potential barrier. For the copolymer with a well-barrier-well configuration, only under strong enough electric field can the electric charge transfer from the potential well into the barrier and ultimately reach a dynamic balance.
基金supported by the National Basic Research Program of China(Grant Nos. 2013CB934500 and 2012CB921302)the National Natural Science Foundation of China (Grant No. 91223204)the "100 Talents Project" of Chinese Academy of Sciences
文摘Carbon-based spintronics refers mainly to the spin injection and transport in carbon materials including carbon nanotubes,graphene,fullerene,and organic materials.In the last decade,extraordinary development has been achieved for carbon-based spintronics,and the spin transport has been studied in both local and nonlocal spin valve devices.A series of theoretical and experimental studies have been done to reveal the spin relaxation mechanisms and spin transport properties in carbon materials,mostly for graphene and carbon nanotubes.In this article,we provide a brief review on spin injection and transport in graphene,carbon nanotubes,fullerene and organic thin films.
