Inspired by biological systems that have the inherent skill to generate considerable bioelectricity from the salt content in fluids with highly selective ion channels and pumps on cell membranes, herein, a fully abiot...Inspired by biological systems that have the inherent skill to generate considerable bioelectricity from the salt content in fluids with highly selective ion channels and pumps on cell membranes, herein, a fully abiotic, single glass conical nanopores energy-harvesting is demonstrated. Ion current rectification （ICR） in negatively charged glass conical nanopores is shown to be controlled by the electrolyte concentration gradient depending on the direction of ion diffusion. The degree of ICR is enhanced with the increasing forward concentration difference. An unusual rectification inversion is observed when the concentration gradient is reversely applied. The maximum power output with the individual nanopore approaches 10^4pW. This facile and cost-efficient energy-harvesting system has the potential to power tiny biomedical devices or construct future clean-energy recovery plants.展开更多
The impurity iron in silicon material will seriously affect the photoelectric conversion efficiency of silicon solar cells.However,the traditional silicon purification method has the disadvantages of long cycle,high e...The impurity iron in silicon material will seriously affect the photoelectric conversion efficiency of silicon solar cells.However,the traditional silicon purification method has the disadvantages of long cycle,high energy consumption and serious pollution.In this study,an efficient and green pulsed electric current purification technology is proposed.The electromigration effect of iron elements,the current density gradient driving of iron phase,and the gravity of iron phase all affect the migration behavior of iron phase in silicon melt under pulsed electric current.Regardless of the depth of electrode insertion into the silicon melt,the solubility of iron in silicon decreases under the pulsed electric current,which helps to form the iron phase.At the same time,the iron phase tends to sink toward the bottom under the influence of gravity.When the electrode is shallowly inserted,a non-uniform electric field is formed in the silicon melt,and the iron phase is mainly driven by the current density gradient to accelerate sink toward the bottom.When the electrode is fully inserted,an approximately uniform electric field is formed in the silicon melt,and iron elements are preferentially migrated to the cathode by electromigration,forming iron phase sinking at the cathode.The study of impurity iron migration behavior in silicon melt under pulsed electric current provides a new approach for the purification of polycrystalline silicon.展开更多
Using a Finite-Volume Community Ocean Model, we investigated the dynamic mechanism of the South China Sea Warm Current(SCSWC) in the northern South China Sea(NSCS) during winter monsoon relaxation. The model reproduce...Using a Finite-Volume Community Ocean Model, we investigated the dynamic mechanism of the South China Sea Warm Current(SCSWC) in the northern South China Sea(NSCS) during winter monsoon relaxation. The model reproduces the mean surface circulation of the NSCS during winter, while model-simulated subtidal currents generally capture its current pattern. The model shows that the current over the continental shelf is generally southwestward, under a strong winter monsoon condition, but a northeastward counter-wind current usually develops between 50-and 100-m isobaths, when the monsoon relaxes. Model experiments, focusing on the wind relaxation process, show that sea level is elevated in the northwestern South China Sea(SCS), related to the persistent northeasterly monsoon. Following wind relaxation, a high sea level band builds up along the mid-shelf, and a northeastward current develops, having an obvious vertical barotropic structure. Momentum balance analysis indicates that an along-shelf pressure gradient provides the initial driving force for the SCSWC during the first few days following wind relaxation. The SCSWC subsequently reaches a steady quasi-geostrophic balance in the cross-shelf direction, mainly linked to sea level adjustment over the shelf. Lagrangian particle tracking experiments show that both the southwestward coastal current and slope current contribute to the northeastward movement of the SCSWC during winter monsoon relaxation.展开更多
Based on a general review of marine renewable energy in China, an assessment of the development status and amount of various marine renewable energy resources, including tidal energy, tidal current energy, wave energy...Based on a general review of marine renewable energy in China, an assessment of the development status and amount of various marine renewable energy resources, including tidal energy, tidal current energy, wave energy, ocean thermal energy, and salinity gradient energy in China＇s coastal seas, such as the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea, is presented. We have found that these kinds of marine renewable energy resources will play an important role in meeting China＇s future energy needs. Additionally, considering the uneven distribution of China＇s marine renewable energy and the influences of its exploitation on the environment, we have suggested several sites with great potential for each kind of marine energy. Furthermore, perspectives on and challenges related with marine renewable energy in China are addressed.展开更多
The geotemperature gradient is considered as taking main part in generating the Earth’s magnetic field. It is shown that geotemperature gradient functions as a generator of both nuclear and mantle thermoelectrical cu...The geotemperature gradient is considered as taking main part in generating the Earth’s magnetic field. It is shown that geotemperature gradient functions as a generator of both nuclear and mantle thermoelectrical currents thanks to the great temperature difference between the core and the mantle. The movement of those currents is close to the radial direction towards the Earth’s crust. However, the nuclear thermocurrents movement tends to cyclically change into opposite one. If the mantle and core thermocurrents move oppositely, the Earth’s crust cools down globally and ice age comes, but if they move unidirectionally then global warming comes. The calculation show that the Earth’s surface can warm up to not more than 10°C. The latter, considering how human factor affects the warming of Earth, is incomparably great. There are calculations that show power of the Earth’s thermocurrents being enough to generate and maintain the Earth’s magnetic field, its modern dynamics and the poles inversion.展开更多
为了更好地设计高压直流(high voltage direct current,HVDC)交联聚乙烯(crosslinked polyethyline,XLPE)绝缘海底电缆,加快高压直流海底电缆绝缘国产化进程,结合电缆绝缘电导率试验方法测定某高压直流海底电缆XLPE绝缘材料在不同温度...为了更好地设计高压直流(high voltage direct current,HVDC)交联聚乙烯(crosslinked polyethyline,XLPE)绝缘海底电缆,加快高压直流海底电缆绝缘国产化进程,结合电缆绝缘电导率试验方法测定某高压直流海底电缆XLPE绝缘材料在不同温度及不同电场强度下的电导率;利用COMSOL多物理场仿真软件,采用分步式耦合分析方法,在相同敷设条件、不同负载电流下,对高压直流海底电缆绝缘内部的温度场、电场强度及空间电荷分布情况进行表征。仿真结果表明:采用分步式耦合分析方法可大幅减少模型求解时间,提升计算效率;在正常工作条件下,直流海底电缆绝缘内部会产生温度梯度和电场强度梯度,导致电导率发生变化,并进一步影响绝缘内部电场强度的分布;在电缆线芯的负载电流增大至一定程度时,出现场强反转现象;在绝缘内、外表面均会产生空间电荷积聚现象。文中仿真结果可为高压直流海底电缆的结构设计和国产绝缘材料开发提供理论依据和参考。展开更多
针对埋地钢套钢蒸汽管道,提出一种检测方法,即采用开天窗形式,利用多频管中电流法(Pipeline Current Mapper,PCM)和交流电位梯度检测技术(Alternating Current Voltage Gradient,ACVG)检测防腐层状况,之后采用超声波测厚和数字化X线摄影...针对埋地钢套钢蒸汽管道,提出一种检测方法,即采用开天窗形式,利用多频管中电流法(Pipeline Current Mapper,PCM)和交流电位梯度检测技术(Alternating Current Voltage Gradient,ACVG)检测防腐层状况,之后采用超声波测厚和数字化X线摄影(Digital Radiography,DR)技术,查验管道在280℃工作环境下的焊缝及母材腐蚀情况。应用上述埋地钢套钢蒸汽管道检测方法,能够在满足《压力管道安全技术监察规程》要求的前提下,排查隐患和缺陷,确保蒸汽管道安全运行。展开更多
基金financial support from the National Natural Science Foundation of China(Nos.21375111,21127005,20975084)the Ph.D.Programs Foundation of the Ministry of Education of China(No.20110121110011)
文摘Inspired by biological systems that have the inherent skill to generate considerable bioelectricity from the salt content in fluids with highly selective ion channels and pumps on cell membranes, herein, a fully abiotic, single glass conical nanopores energy-harvesting is demonstrated. Ion current rectification （ICR） in negatively charged glass conical nanopores is shown to be controlled by the electrolyte concentration gradient depending on the direction of ion diffusion. The degree of ICR is enhanced with the increasing forward concentration difference. An unusual rectification inversion is observed when the concentration gradient is reversely applied. The maximum power output with the individual nanopore approaches 10^4pW. This facile and cost-efficient energy-harvesting system has the potential to power tiny biomedical devices or construct future clean-energy recovery plants.
基金financially supported by the National Natural Science Foundation of China(No.U21B2082)Natural Science Foundation of Beijing Municipality(No.2222065)and Fundamental Research Funds for the Central Universities(No.FRF-TP-22-02C2).
文摘The impurity iron in silicon material will seriously affect the photoelectric conversion efficiency of silicon solar cells.However,the traditional silicon purification method has the disadvantages of long cycle,high energy consumption and serious pollution.In this study,an efficient and green pulsed electric current purification technology is proposed.The electromigration effect of iron elements,the current density gradient driving of iron phase,and the gravity of iron phase all affect the migration behavior of iron phase in silicon melt under pulsed electric current.Regardless of the depth of electrode insertion into the silicon melt,the solubility of iron in silicon decreases under the pulsed electric current,which helps to form the iron phase.At the same time,the iron phase tends to sink toward the bottom under the influence of gravity.When the electrode is shallowly inserted,a non-uniform electric field is formed in the silicon melt,and the iron phase is mainly driven by the current density gradient to accelerate sink toward the bottom.When the electrode is fully inserted,an approximately uniform electric field is formed in the silicon melt,and iron elements are preferentially migrated to the cathode by electromigration,forming iron phase sinking at the cathode.The study of impurity iron migration behavior in silicon melt under pulsed electric current provides a new approach for the purification of polycrystalline silicon.
基金Supported by the National Natural Science Foundation of China(Nos.41606005,41430963)the National Science Foundation for Post-Doctoral Scientists of China(No.2015M582133)the Fundamental Research Funds for the Central Universities(No.201713023)
文摘Using a Finite-Volume Community Ocean Model, we investigated the dynamic mechanism of the South China Sea Warm Current(SCSWC) in the northern South China Sea(NSCS) during winter monsoon relaxation. The model reproduces the mean surface circulation of the NSCS during winter, while model-simulated subtidal currents generally capture its current pattern. The model shows that the current over the continental shelf is generally southwestward, under a strong winter monsoon condition, but a northeastward counter-wind current usually develops between 50-and 100-m isobaths, when the monsoon relaxes. Model experiments, focusing on the wind relaxation process, show that sea level is elevated in the northwestern South China Sea(SCS), related to the persistent northeasterly monsoon. Following wind relaxation, a high sea level band builds up along the mid-shelf, and a northeastward current develops, having an obvious vertical barotropic structure. Momentum balance analysis indicates that an along-shelf pressure gradient provides the initial driving force for the SCSWC during the first few days following wind relaxation. The SCSWC subsequently reaches a steady quasi-geostrophic balance in the cross-shelf direction, mainly linked to sea level adjustment over the shelf. Lagrangian particle tracking experiments show that both the southwestward coastal current and slope current contribute to the northeastward movement of the SCSWC during winter monsoon relaxation.
基金supported by the National Natural Science Foundation of China(Grants No.51079072 and 51279088)the National High Technology Research and Development Program of China(Grant No.2012AA052602)the Tsinghua University Initiative Scientific Research Program(Grant No.20101081791)
文摘Based on a general review of marine renewable energy in China, an assessment of the development status and amount of various marine renewable energy resources, including tidal energy, tidal current energy, wave energy, ocean thermal energy, and salinity gradient energy in China＇s coastal seas, such as the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea, is presented. We have found that these kinds of marine renewable energy resources will play an important role in meeting China＇s future energy needs. Additionally, considering the uneven distribution of China＇s marine renewable energy and the influences of its exploitation on the environment, we have suggested several sites with great potential for each kind of marine energy. Furthermore, perspectives on and challenges related with marine renewable energy in China are addressed.
文摘The geotemperature gradient is considered as taking main part in generating the Earth’s magnetic field. It is shown that geotemperature gradient functions as a generator of both nuclear and mantle thermoelectrical currents thanks to the great temperature difference between the core and the mantle. The movement of those currents is close to the radial direction towards the Earth’s crust. However, the nuclear thermocurrents movement tends to cyclically change into opposite one. If the mantle and core thermocurrents move oppositely, the Earth’s crust cools down globally and ice age comes, but if they move unidirectionally then global warming comes. The calculation show that the Earth’s surface can warm up to not more than 10°C. The latter, considering how human factor affects the warming of Earth, is incomparably great. There are calculations that show power of the Earth’s thermocurrents being enough to generate and maintain the Earth’s magnetic field, its modern dynamics and the poles inversion.
文摘为了更好地设计高压直流(high voltage direct current,HVDC)交联聚乙烯(crosslinked polyethyline,XLPE)绝缘海底电缆,加快高压直流海底电缆绝缘国产化进程,结合电缆绝缘电导率试验方法测定某高压直流海底电缆XLPE绝缘材料在不同温度及不同电场强度下的电导率;利用COMSOL多物理场仿真软件,采用分步式耦合分析方法,在相同敷设条件、不同负载电流下,对高压直流海底电缆绝缘内部的温度场、电场强度及空间电荷分布情况进行表征。仿真结果表明:采用分步式耦合分析方法可大幅减少模型求解时间,提升计算效率;在正常工作条件下,直流海底电缆绝缘内部会产生温度梯度和电场强度梯度,导致电导率发生变化,并进一步影响绝缘内部电场强度的分布;在电缆线芯的负载电流增大至一定程度时,出现场强反转现象;在绝缘内、外表面均会产生空间电荷积聚现象。文中仿真结果可为高压直流海底电缆的结构设计和国产绝缘材料开发提供理论依据和参考。
文摘针对埋地钢套钢蒸汽管道,提出一种检测方法,即采用开天窗形式,利用多频管中电流法(Pipeline Current Mapper,PCM)和交流电位梯度检测技术(Alternating Current Voltage Gradient,ACVG)检测防腐层状况,之后采用超声波测厚和数字化X线摄影(Digital Radiography,DR)技术,查验管道在280℃工作环境下的焊缝及母材腐蚀情况。应用上述埋地钢套钢蒸汽管道检测方法,能够在满足《压力管道安全技术监察规程》要求的前提下,排查隐患和缺陷,确保蒸汽管道安全运行。
