Two-phase flow with complex phase interfaces is commonly observed in both nature and industrial processes.The bubble size distribution(BSD) is a crucial parameter in gas-liquid two-phase flow,impacting various flow ch...Two-phase flow with complex phase interfaces is commonly observed in both nature and industrial processes.The bubble size distribution(BSD) is a crucial parameter in gas-liquid two-phase flow,impacting various flow characteristics including interfacial forces,void fraction distribution,and interfacial area transport.Throughout the flow progression,the BSD changes along the channel due to variations in pressure and interactions among bubbles.Accurately predicting the evolution of BSD can enhance the modeling of two-phase flow.This study presents a novel BSD evolution(BSDE) model,where the governing equation for the probability density function is formulated by considering the conservation of bubbles within a onedimensional control volume in the channel.The downstream BSD is predicted based on the upstream BSD and the effects of pressure variations and bubble interactions along the channel.To account for the multiscale nature of the two-phase flow,the bubbles are categorized into small groups(G_(1)) and large groups(G_(2)).Six distinct source term distributions for intra/inter bubble interactions have been developed.Each source term accounts for the distributions of consumed and generated bubbles,ensuring the conservation of bubble volume through constraints on model coefficients.The model has been tested on a tight-lattice rod bundle using experimental data,with deviations of less than 5% and 15% for G_(1)and G_(2) flow,respectively.Since the model development is independent of specific geometry,the framework of the BSDE model can also be effectively applied to channels of varying shapes.展开更多
China is one of the most populated and rapidly urbanizing countries worldwide and was among the earliest countries to integrate sustainable development into urban construction.To achieve high-quality development and i...China is one of the most populated and rapidly urbanizing countries worldwide and was among the earliest countries to integrate sustainable development into urban construction.To achieve high-quality development and implement the objectives of“Transforming Our World:The 2030 Agenda for Sustainable Development”,it is crucial to measure and analyze the current level of sustainable development of cities in China.Following the principles of relevance,scientific rigor,universality,reliability,and timeliness,this study constructs an assessment index system for sustainable development,covering seven themes corresponding to the UN Sustainable Development Goal 11.Through detailed calculations,we obtained sustainable development indices for 139 Chinese cities from 2016 to 2022 and analyzed them in three dimensions:distribution dynamics,regional differences,and convergence.The key findings are as follows.First,the level of sustainable development showed improvement,with the average score of included cities increasing by 11.88%from 2016 to 2022.Second,the level of sustainable development was relatively balanced,maintaining low Gini coefficients between 0.05 and 0.06.Third,a weak overallσconvergence feature existed,with increased differentiation in 2021.From a regional perspective,aσconvergence feature was observed in the northeastern but not in the western region.Fourth,both overall absoluteβ-convergence and conditionalβeffects were significant.Regional absoluteβ-convergence and conditionalβ-convergence were also significant.This study contributes to the literature by providing evidence of China’s urban sustainable development,offering policy insights for deepening the implementation of development goals in the future,and providing experiential reference for other developing countries to achieve sustainable development.展开更多
In order to investigate the effect of water content on the energy evolution of red sandstone, the axial loading–unloading experiments on dry and water-saturated sandstone samples were conducted, and the distribution ...In order to investigate the effect of water content on the energy evolution of red sandstone, the axial loading–unloading experiments on dry and water-saturated sandstone samples were conducted, and the distribution and evolution of elastic energy and dissipated energy within the rock were measured.The results show that the saturation process from dry to fully-saturated states reduces the strength, rigidity and brittleness of the rock by 30.2%, 25.5% and 16.7%, respectively. The water-saturated sample has larger irreversible deformation in the pre-peak stage and smaller stress drop in the post-peak stage.The saturation process decreases the accumulation energy limit by 38.9%, but increases the dissipated energy and residual elastic energy density, thus greatly reducing the magnitude and rate of energy release. The water-saturated sample has lower conversion efficiency to elastic energy by 3% in the prepeak region; moreover, the elastic energy ratio falls with a smaller range in the post-peak stage.Therefore, saturation process can greatly reduce the risk of dynamic disaster, and heterogeneous water content can lead to dynamic disaster possibly on the other hand.展开更多
This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average r...This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average reanalysis data.The study employs techniques such as empirical orthogonal function(EOF)decomposition,MannKendall mutation and other methods to investigate the spatiotemporal distribution of extreme precipitation index in northern Shanxi and their correlation with atmospheric circulation.The research results show that:the absolute index,relative index,intensity index and sustained dry period index(CDD)in the continuous index appear from southwest to northeast.The spatial distribution characteristics of the central region decrease,while the continuous wet period(CWD)decreases from the central to the east and west.The three indices Rx1day,Rx5day,and CWD mutated in 1978,1975,and 1983 respectively,and other extreme precipitation indices all appeared in a sudden change from a low-value period to a high-value period occurred around 2010.In the high-value years of the summer extreme precipitation index,there is a significant negative anomaly in the height field in the mid-high latitude regions of Eurasia.Northern Shanxi is controlled by a broad low-pressure trough in the Lake Baikal area.Water vapor transported via the east,west,and south routes converges in the northern Shanxi region and encounters cold air from the north.There is a strong upward motion anomaly at 500 hPa in the troposphere,and the dynamic conditions of upper-level divergence and lower-level convergence lead to more summer extreme precipitation in the northern Shanxi region.Conversely,in the low-value years of the summer extreme precipitation index,northern Shanxi is affected by a strong high-pressure ridge north of Lake Baikal.There is a downward motion anomaly at 500 hPa,and the northern Shanxi region lacks water vapor.The cold and warm air cannot converge,and both the water vapor conditions and dynamic conditions are poor,which is not conducive to the production of extreme precipitation in northern Shanxi.展开更多
We investigate the superposition properties of the dipole and quadrupole plasmon modes in the near field both experimentally, by using photoemission electron microscopy(PEEM), and theoretically. In particular, the asy...We investigate the superposition properties of the dipole and quadrupole plasmon modes in the near field both experimentally, by using photoemission electron microscopy(PEEM), and theoretically. In particular, the asymmetric near-field distributions on gold(Au) nanodisks and nanoblocks under oblique incidence with different polarizations are investigated in detail. The results of PEEM measurements show that the evolutions of the asymmetric near-field distributions are different between the excitation with s-polarized and p-polarized light.The experimental results can be reproduced very well by numerical simulations and interpreted as the superposition of the dipole and quadrupole modes with the help of analytic calculations. Moreover, we hypothesize that the electrons collected by PEEM are mainly from the plasmonic hot spots located at the plane in the interface between the Au particles and the substrate in the PEEM experiments.展开更多
In this paper,the type,vertical evolution,and distribution pattern of sedimentary facies of the Paleogene Dainan Formation in the Gaoyou Depression of the North Jiangsu Basin are studied in detail.Results show that fa...In this paper,the type,vertical evolution,and distribution pattern of sedimentary facies of the Paleogene Dainan Formation in the Gaoyou Depression of the North Jiangsu Basin are studied in detail.Results show that fan delta,delta,nearshore subaqueous fan,and lacustrine facies developed during the Dainan Formation period and their distribution pattern was mainly controlled by tectonics and paleogeography.The fan delta and nearshore subaqueous fan facies predominantly occur in the southern steep slope region where fault-induced subsidence is thought to have created substantial accommodation,whereas the delta facies are distributed on the northern gentle slope which is thought to have experienced less subsidence.Finally,the lacustrine facies is shown to have developed in the center of the depression,as well as on the flanks of the fan delta,delta,and nearshore subaqueous fan facies.Vertically,the Dainan Formation represents an integrated transgressiveregressive cycle,with the E2d1being the transgressive sequence and the E2d2being the regressive sequence.This distribution model of sedimentary facies plays an important role in predicting favorable reservoir belts for the Dainan Formation in the Gaoyou Depression and similar areas.In the Gaoyou Depression,sandstones of the subaqueous distributary channels in the fan delta and the subaqueous branch channels in the delta are characterized by physical properties favorable for reservoir formation.展开更多
Purpose： This study aims to reveal the landscape and trends ofgraphene research in the world by using data from Chemical Abstracts Service （CAS）. Design/methodology/approach： Index data from CAS have been retrieve...Purpose： This study aims to reveal the landscape and trends ofgraphene research in the world by using data from Chemical Abstracts Service （CAS）. Design/methodology/approach： Index data from CAS have been retrieved on 78,756 papers and 23,057 patents on graphene from 1985 to March 2016, and scientometric methods were used to analyze the growth and distribution of R＆D output, topic distribution and evolution, and distribution and evolution of substance properties and roles. Findings： In recent years R＆D in graphene keeps in rapid growth, while China, South Korea and United States are the largest producers in research but China is relatively weak in patent applications in other countries. Research topics in graphene are continuously expanding from mechanical, material, and electrical properties to a diverse range of application areas such as batteries, capacitors, semiconductors, and sensors devices. The roles of emerging substances are increasing in Preparation and Biological Study. More techniques have been included to improve the preparation processes and applications of graphene in various fields. Research limitations： Only data from CAS is used and some R＆D activities solely reported through other channels may be missed. Also more detailed analysis need to be done to reveal the impact of research on development or vice verse, development dynamics among the players, and impact of emerging terms or substance roles on research and technology development. Practical implications： This will provide a valuable reference for scientists and developers, R＆D managers, R＆D policy makers, industrial and business investers to understand the landscape and trends ofgraphene research. Its methodologies can be applied to other fields or with data from other similar sources.Originality/value： The integrative use of indexing data on papers and patents of CAS and the systematic exploration of the distribution trends in output, topics, substance roles are distinctive and insightful.展开更多
基金supported by the National Natural Science Foundation of China (12322510 and 12275174)the Shanghai Rising-Star Program (22QA1404500)+1 种基金the Science and Technology Commission of Shanghai Municipality (24DZ3100300)the Lingchuang Project of China National Nuclear Corporation
文摘Two-phase flow with complex phase interfaces is commonly observed in both nature and industrial processes.The bubble size distribution(BSD) is a crucial parameter in gas-liquid two-phase flow,impacting various flow characteristics including interfacial forces,void fraction distribution,and interfacial area transport.Throughout the flow progression,the BSD changes along the channel due to variations in pressure and interactions among bubbles.Accurately predicting the evolution of BSD can enhance the modeling of two-phase flow.This study presents a novel BSD evolution(BSDE) model,where the governing equation for the probability density function is formulated by considering the conservation of bubbles within a onedimensional control volume in the channel.The downstream BSD is predicted based on the upstream BSD and the effects of pressure variations and bubble interactions along the channel.To account for the multiscale nature of the two-phase flow,the bubbles are categorized into small groups(G_(1)) and large groups(G_(2)).Six distinct source term distributions for intra/inter bubble interactions have been developed.Each source term accounts for the distributions of consumed and generated bubbles,ensuring the conservation of bubble volume through constraints on model coefficients.The model has been tested on a tight-lattice rod bundle using experimental data,with deviations of less than 5% and 15% for G_(1)and G_(2) flow,respectively.Since the model development is independent of specific geometry,the framework of the BSDE model can also be effectively applied to channels of varying shapes.
基金supported by the National Key Research and Development Program of China under the theme“Research on urban sustainable development evaluation data fusion management technology” [Grant No.2022YFC3802903].
文摘China is one of the most populated and rapidly urbanizing countries worldwide and was among the earliest countries to integrate sustainable development into urban construction.To achieve high-quality development and implement the objectives of“Transforming Our World:The 2030 Agenda for Sustainable Development”,it is crucial to measure and analyze the current level of sustainable development of cities in China.Following the principles of relevance,scientific rigor,universality,reliability,and timeliness,this study constructs an assessment index system for sustainable development,covering seven themes corresponding to the UN Sustainable Development Goal 11.Through detailed calculations,we obtained sustainable development indices for 139 Chinese cities from 2016 to 2022 and analyzed them in three dimensions:distribution dynamics,regional differences,and convergence.The key findings are as follows.First,the level of sustainable development showed improvement,with the average score of included cities increasing by 11.88%from 2016 to 2022.Second,the level of sustainable development was relatively balanced,maintaining low Gini coefficients between 0.05 and 0.06.Third,a weak overallσconvergence feature existed,with increased differentiation in 2021.From a regional perspective,aσconvergence feature was observed in the northeastern but not in the western region.Fourth,both overall absoluteβ-convergence and conditionalβeffects were significant.Regional absoluteβ-convergence and conditionalβ-convergence were also significant.This study contributes to the literature by providing evidence of China’s urban sustainable development,offering policy insights for deepening the implementation of development goals in the future,and providing experiential reference for other developing countries to achieve sustainable development.
基金provided by the Fundamental Research Funds for the Central Universities(No.2014QNA80)the Project funded by China Postdoctoral Science Foundation(No.2014M550315)+2 种基金a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe National Natural Science Foundation of China(No.11202108)the Natural Science Foundation of Jiangsu Province(No.BK20140189)
文摘In order to investigate the effect of water content on the energy evolution of red sandstone, the axial loading–unloading experiments on dry and water-saturated sandstone samples were conducted, and the distribution and evolution of elastic energy and dissipated energy within the rock were measured.The results show that the saturation process from dry to fully-saturated states reduces the strength, rigidity and brittleness of the rock by 30.2%, 25.5% and 16.7%, respectively. The water-saturated sample has larger irreversible deformation in the pre-peak stage and smaller stress drop in the post-peak stage.The saturation process decreases the accumulation energy limit by 38.9%, but increases the dissipated energy and residual elastic energy density, thus greatly reducing the magnitude and rate of energy release. The water-saturated sample has lower conversion efficiency to elastic energy by 3% in the prepeak region; moreover, the elastic energy ratio falls with a smaller range in the post-peak stage.Therefore, saturation process can greatly reduce the risk of dynamic disaster, and heterogeneous water content can lead to dynamic disaster possibly on the other hand.
基金supported by the National Natural Science Foundation of China (41575091)China Meteorological Administration Training Centre scientific research project (Study on impacting factors of regional climate in China)+1 种基金Shanxi Provincial Meteorological Bureau project (SXKMSQH20236329)Heze University Research Fund Program (Poverty Alleviation Project) (XY18FP08)
文摘This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020,and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average reanalysis data.The study employs techniques such as empirical orthogonal function(EOF)decomposition,MannKendall mutation and other methods to investigate the spatiotemporal distribution of extreme precipitation index in northern Shanxi and their correlation with atmospheric circulation.The research results show that:the absolute index,relative index,intensity index and sustained dry period index(CDD)in the continuous index appear from southwest to northeast.The spatial distribution characteristics of the central region decrease,while the continuous wet period(CWD)decreases from the central to the east and west.The three indices Rx1day,Rx5day,and CWD mutated in 1978,1975,and 1983 respectively,and other extreme precipitation indices all appeared in a sudden change from a low-value period to a high-value period occurred around 2010.In the high-value years of the summer extreme precipitation index,there is a significant negative anomaly in the height field in the mid-high latitude regions of Eurasia.Northern Shanxi is controlled by a broad low-pressure trough in the Lake Baikal area.Water vapor transported via the east,west,and south routes converges in the northern Shanxi region and encounters cold air from the north.There is a strong upward motion anomaly at 500 hPa in the troposphere,and the dynamic conditions of upper-level divergence and lower-level convergence lead to more summer extreme precipitation in the northern Shanxi region.Conversely,in the low-value years of the summer extreme precipitation index,northern Shanxi is affected by a strong high-pressure ridge north of Lake Baikal.There is a downward motion anomaly at 500 hPa,and the northern Shanxi region lacks water vapor.The cold and warm air cannot converge,and both the water vapor conditions and dynamic conditions are poor,which is not conducive to the production of extreme precipitation in northern Shanxi.
基金Japan Society for the Promotion of Science(JSPS)(JP15H00856,JP15H01073,JP15K04589,JP23225006,JP26870014)National Natural Science Foundation of China(NSFC)(11527901)
文摘We investigate the superposition properties of the dipole and quadrupole plasmon modes in the near field both experimentally, by using photoemission electron microscopy(PEEM), and theoretically. In particular, the asymmetric near-field distributions on gold(Au) nanodisks and nanoblocks under oblique incidence with different polarizations are investigated in detail. The results of PEEM measurements show that the evolutions of the asymmetric near-field distributions are different between the excitation with s-polarized and p-polarized light.The experimental results can be reproduced very well by numerical simulations and interpreted as the superposition of the dipole and quadrupole modes with the help of analytic calculations. Moreover, we hypothesize that the electrons collected by PEEM are mainly from the plasmonic hot spots located at the plane in the interface between the Au particles and the substrate in the PEEM experiments.
基金financially supported by the National Natural Science Foundation of China (Grants Nos. 41272124 and 41402092)Natural Science Foundation (Youth Science Fund Project) of Jiangsu Province (BK20140604)+1 种基金the Fundamental Research Funds for the Central Universities (20620140386)the State Key Laboratory for Mineral Deposits Research of Nanjing University (Grant No. ZZKT-201321)
文摘In this paper,the type,vertical evolution,and distribution pattern of sedimentary facies of the Paleogene Dainan Formation in the Gaoyou Depression of the North Jiangsu Basin are studied in detail.Results show that fan delta,delta,nearshore subaqueous fan,and lacustrine facies developed during the Dainan Formation period and their distribution pattern was mainly controlled by tectonics and paleogeography.The fan delta and nearshore subaqueous fan facies predominantly occur in the southern steep slope region where fault-induced subsidence is thought to have created substantial accommodation,whereas the delta facies are distributed on the northern gentle slope which is thought to have experienced less subsidence.Finally,the lacustrine facies is shown to have developed in the center of the depression,as well as on the flanks of the fan delta,delta,and nearshore subaqueous fan facies.Vertically,the Dainan Formation represents an integrated transgressiveregressive cycle,with the E2d1being the transgressive sequence and the E2d2being the regressive sequence.This distribution model of sedimentary facies plays an important role in predicting favorable reservoir belts for the Dainan Formation in the Gaoyou Depression and similar areas.In the Gaoyou Depression,sandstones of the subaqueous distributary channels in the fan delta and the subaqueous branch channels in the delta are characterized by physical properties favorable for reservoir formation.
文摘Purpose： This study aims to reveal the landscape and trends ofgraphene research in the world by using data from Chemical Abstracts Service （CAS）. Design/methodology/approach： Index data from CAS have been retrieved on 78,756 papers and 23,057 patents on graphene from 1985 to March 2016, and scientometric methods were used to analyze the growth and distribution of R＆D output, topic distribution and evolution, and distribution and evolution of substance properties and roles. Findings： In recent years R＆D in graphene keeps in rapid growth, while China, South Korea and United States are the largest producers in research but China is relatively weak in patent applications in other countries. Research topics in graphene are continuously expanding from mechanical, material, and electrical properties to a diverse range of application areas such as batteries, capacitors, semiconductors, and sensors devices. The roles of emerging substances are increasing in Preparation and Biological Study. More techniques have been included to improve the preparation processes and applications of graphene in various fields. Research limitations： Only data from CAS is used and some R＆D activities solely reported through other channels may be missed. Also more detailed analysis need to be done to reveal the impact of research on development or vice verse, development dynamics among the players, and impact of emerging terms or substance roles on research and technology development. Practical implications： This will provide a valuable reference for scientists and developers, R＆D managers, R＆D policy makers, industrial and business investers to understand the landscape and trends ofgraphene research. Its methodologies can be applied to other fields or with data from other similar sources.Originality/value： The integrative use of indexing data on papers and patents of CAS and the systematic exploration of the distribution trends in output, topics, substance roles are distinctive and insightful.
