The Young's modulus, shear modulus and Poisson's ratio of monolayer arsenene with different sizes were calculated by finite element method, so as to explore the influence of dimension and orientation on the me...The Young's modulus, shear modulus and Poisson's ratio of monolayer arsenene with different sizes were calculated by finite element method, so as to explore the influence of dimension and orientation on the mechanical properties of monolayer arsenene. The calculation results show that the small size has a significant effect on the mechanical properties of the monolayer arsenene. The smaller the size, the larger the Young's modulus and Poisson's ratio of the monolayer arsenene. The size change has a great influence on the Young's modulus of the arsenene handrail direction, and the Young's modulus of the zigzag direction is not sensitive to the size change. Similarly, the size change has a significant effect on the shear modulus of arsenene in the handrail direction, while the shear modulus in the zigzag direction has no significant effect on its size change. For the Poisson's ratio, the situation is just the opposite, and the effect of the size change on the Poisson's ratio of the arsenene zigzag direction is greater than that of the handrail direction.展开更多
In this study,the relationship of tropical cyclone(TC)size change rate(SCR),within 24 hours,with size,intensity,and intensity change rate(ICR)are explored over the western North Pacific.TC size is defined as the azimu...In this study,the relationship of tropical cyclone(TC)size change rate(SCR),within 24 hours,with size,intensity,and intensity change rate(ICR)are explored over the western North Pacific.TC size is defined as the azimuthally averaged radius of gale-force wind of 17 m s−1(R17)based on the Multiplatform Tropical Cyclone Surface Winds Analysis data.The majority of SCRs are mainly distributed in the range from−20 to 80 km d−1.The correlation coefficients between SCR and size(SCR-R17),intensity,and ICR(SCR-ICR)are−0.43,−0.12,and 0.25,respectively.The sensitivity of the SCR-R17 and SCR-ICR relationships to size,intensity,and evolution stage are further examined.Results show that the SCR-R17 relationship is more sensitive to variations of size and evolution stage than that of intensity.The relationship of SCR-ICR is largely modulated by the evolution stage.The correlation coefficient of SCR-ICR can increase from 0.25 to 0.40 when only considering the lifetime stages concurrently before and after the lifetime maximum size(LMS)and lifetime maximum intensity.This demonstrates that ICR is a potential factor in predicting SCR during these evolution stages.Besides,the TC size expansion(shrinkage)is more likely to occur for TCs with smaller(larger)size and weaker(stronger)intensity.The complexity of size change during a TC's lifetime can be attributed to the fact that shrinkage or expansion could occur both before and after LMS.展开更多
ased on the most recent data from the 1990 census, this paper analyses the trend of the changing household size and structure, and the socioeconomic causes beginning in the 1950s. The relationship between the househol...ased on the most recent data from the 1990 census, this paper analyses the trend of the changing household size and structure, and the socioeconomic causes beginning in the 1950s. The relationship between the household size and structure and China's population policy is also analyzed in the paper. Two different categories of socioeconomic factors have been identified which operate in opposition to each other, influencing the increase and decrease in the desirability of co-residence of domestic groups. The future household size and structure is determined by both of them.展开更多
Focusing on the Zengmu-Beikang Basin in the southern South China Sea,we summarized the regional sequence stratigraphic framework and identified mass-transport complex(MTC)that had developed since the Late Miocene(10.5...Focusing on the Zengmu-Beikang Basin in the southern South China Sea,we summarized the regional sequence stratigraphic framework and identified mass-transport complex(MTC)that had developed since the Late Miocene(10.5 Ma),by using high-resolution multibeam bathymetric and 2D seismic datasets.Based on the analysis of high amplitude and continuous seismic reflections within the mass-transport deposits(MTDs),we identified 14 basal shear surfaces(BSS)and divided the MTC into 14 units(MTD1–MTD14 from the youngest to the oldest in numerical order).Two types of seismic facies and five seismic features within the MTDs were recognized,including chaotic and transparent facies(debris flow),chaotic and semi-transparent facies(debris flow),thrust-fold systems,blocks,escarpments,pressure ridges,and normal faults.Analysis of the depositional area,frequency,and vertical extent of the escarpments of the fourteen MTD units revealed their variations in dimensions.Specifically,MTD14–MTD4 exhibited a gradual increase in the size of the deposition unit,with larger-sized MTD7–MTD4;while MTD3–MTD1 showed a gradual decrease in the size.The evolution of the MTDs in the study area is primarily controlled by several factors,including erosion of mass-movement processes(e.g.,slide,slump,and mass flows),sea-level fluctuation and sediment supply,tectonic activity,development of mud diapirs,and topographic influence.It is also plausible that the large-sized MTD7–MTD4 might be formed in the Pliocene due to steep slope gradient and instability caused by the development of mud diapirs,whereas in the Quaternary,the influence of mud diapirs in the shallow strata diminished,and smaller-sized MTD3–MTD1 were formed.展开更多
Based on the data from China Statistical Yearbooks and China’s population cen-suses,this paper provides a systematic introduction to changes in the size of China’s population over the 70 years since the founding of ...Based on the data from China Statistical Yearbooks and China’s population cen-suses,this paper provides a systematic introduction to changes in the size of China’s population over the 70 years since the founding of the People’s Republic of China(PRC)in 1949.It analyzes population size and crude birth rate,crude death rate,natural increase rate and total fertility rate,all of which have an impact on popula-tion size in both the temporal and spatial dimensions.The paper divides China into sluggish Average Annual Growth Rate(AAGR)regions,recovering AAGR regions,and thriving AAGR regions.Challenges that may result from China’s demographic changes and strategies to address those challenges are discussed.展开更多
Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for p...Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for polyhedral particles. In this short communication, a novel approach that locally resolves the particle shapes where needed and uses a simplified representation elsewhere, to accelerate simulations without compromising accuracy, is presented. For this purpose, a method employing a smooth transition of the particle shape representation from analytical spheres to shape-resolving polyhedra is introduced in DEM. The feasibility and correct implementation of this approach are demonstrated through simulations of hopper discharge involving spherical and dodecahedral particles from a flat bottom silo or shaft kiln. The model capabilities, in terms of accuracy as well as reduction in computational effort, are quantified for a moving bed with continuous outflow.展开更多
基金Funded by Project of Liaoning Provincial Department of Education (No.LZGD2019003)。
文摘The Young's modulus, shear modulus and Poisson's ratio of monolayer arsenene with different sizes were calculated by finite element method, so as to explore the influence of dimension and orientation on the mechanical properties of monolayer arsenene. The calculation results show that the small size has a significant effect on the mechanical properties of the monolayer arsenene. The smaller the size, the larger the Young's modulus and Poisson's ratio of the monolayer arsenene. The size change has a great influence on the Young's modulus of the arsenene handrail direction, and the Young's modulus of the zigzag direction is not sensitive to the size change. Similarly, the size change has a significant effect on the shear modulus of arsenene in the handrail direction, while the shear modulus in the zigzag direction has no significant effect on its size change. For the Poisson's ratio, the situation is just the opposite, and the effect of the size change on the Poisson's ratio of the arsenene zigzag direction is greater than that of the handrail direction.
基金This study was supported by the National Natural Science Foundation of China[grant numbers 41975071 and 41775063].
文摘In this study,the relationship of tropical cyclone(TC)size change rate(SCR),within 24 hours,with size,intensity,and intensity change rate(ICR)are explored over the western North Pacific.TC size is defined as the azimuthally averaged radius of gale-force wind of 17 m s−1(R17)based on the Multiplatform Tropical Cyclone Surface Winds Analysis data.The majority of SCRs are mainly distributed in the range from−20 to 80 km d−1.The correlation coefficients between SCR and size(SCR-R17),intensity,and ICR(SCR-ICR)are−0.43,−0.12,and 0.25,respectively.The sensitivity of the SCR-R17 and SCR-ICR relationships to size,intensity,and evolution stage are further examined.Results show that the SCR-R17 relationship is more sensitive to variations of size and evolution stage than that of intensity.The relationship of SCR-ICR is largely modulated by the evolution stage.The correlation coefficient of SCR-ICR can increase from 0.25 to 0.40 when only considering the lifetime stages concurrently before and after the lifetime maximum size(LMS)and lifetime maximum intensity.This demonstrates that ICR is a potential factor in predicting SCR during these evolution stages.Besides,the TC size expansion(shrinkage)is more likely to occur for TCs with smaller(larger)size and weaker(stronger)intensity.The complexity of size change during a TC's lifetime can be attributed to the fact that shrinkage or expansion could occur both before and after LMS.
文摘ased on the most recent data from the 1990 census, this paper analyses the trend of the changing household size and structure, and the socioeconomic causes beginning in the 1950s. The relationship between the household size and structure and China's population policy is also analyzed in the paper. Two different categories of socioeconomic factors have been identified which operate in opposition to each other, influencing the increase and decrease in the desirability of co-residence of domestic groups. The future household size and structure is determined by both of them.
基金Supported by the Guangzhou Marine Geology Survey,China Geological Survey(No.DD 20160155)。
文摘Focusing on the Zengmu-Beikang Basin in the southern South China Sea,we summarized the regional sequence stratigraphic framework and identified mass-transport complex(MTC)that had developed since the Late Miocene(10.5 Ma),by using high-resolution multibeam bathymetric and 2D seismic datasets.Based on the analysis of high amplitude and continuous seismic reflections within the mass-transport deposits(MTDs),we identified 14 basal shear surfaces(BSS)and divided the MTC into 14 units(MTD1–MTD14 from the youngest to the oldest in numerical order).Two types of seismic facies and five seismic features within the MTDs were recognized,including chaotic and transparent facies(debris flow),chaotic and semi-transparent facies(debris flow),thrust-fold systems,blocks,escarpments,pressure ridges,and normal faults.Analysis of the depositional area,frequency,and vertical extent of the escarpments of the fourteen MTD units revealed their variations in dimensions.Specifically,MTD14–MTD4 exhibited a gradual increase in the size of the deposition unit,with larger-sized MTD7–MTD4;while MTD3–MTD1 showed a gradual decrease in the size.The evolution of the MTDs in the study area is primarily controlled by several factors,including erosion of mass-movement processes(e.g.,slide,slump,and mass flows),sea-level fluctuation and sediment supply,tectonic activity,development of mud diapirs,and topographic influence.It is also plausible that the large-sized MTD7–MTD4 might be formed in the Pliocene due to steep slope gradient and instability caused by the development of mud diapirs,whereas in the Quaternary,the influence of mud diapirs in the shallow strata diminished,and smaller-sized MTD3–MTD1 were formed.
文摘Based on the data from China Statistical Yearbooks and China’s population cen-suses,this paper provides a systematic introduction to changes in the size of China’s population over the 70 years since the founding of the People’s Republic of China(PRC)in 1949.It analyzes population size and crude birth rate,crude death rate,natural increase rate and total fertility rate,all of which have an impact on popula-tion size in both the temporal and spatial dimensions.The paper divides China into sluggish Average Annual Growth Rate(AAGR)regions,recovering AAGR regions,and thriving AAGR regions.Challenges that may result from China’s demographic changes and strategies to address those challenges are discussed.
基金funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project-ID 422037413-TRR 287Gefördert durch die Deutsche Forschungsgemeinschaft(DFG)-Projektnummer 422037413-TRR 287.
文摘Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for polyhedral particles. In this short communication, a novel approach that locally resolves the particle shapes where needed and uses a simplified representation elsewhere, to accelerate simulations without compromising accuracy, is presented. For this purpose, a method employing a smooth transition of the particle shape representation from analytical spheres to shape-resolving polyhedra is introduced in DEM. The feasibility and correct implementation of this approach are demonstrated through simulations of hopper discharge involving spherical and dodecahedral particles from a flat bottom silo or shaft kiln. The model capabilities, in terms of accuracy as well as reduction in computational effort, are quantified for a moving bed with continuous outflow.
