The high-resolution and nondestructive co-reference measurement of the inner and outer threedimensional(3D)surface profiles of laser fusion targets is difficult to achieve.In this study,we propose a laser differential...The high-resolution and nondestructive co-reference measurement of the inner and outer threedimensional(3D)surface profiles of laser fusion targets is difficult to achieve.In this study,we propose a laser differential confocal(LDC)–atomic force probe(AFP)method to measure the inner and outer 3D surface profiles of laser fusion targets at a high resolution.This method utilizes the LDC method to detect the deflection of the AFP and exploits the high spatial resolution of the AFP to enhance the spatial resolution of the outer profile measurement.Nondestructive and co-reference measurements of the inner profile of a target were achieved using the tomographic characteristics of the LDC method.Furthermore,by combining multiple repositionings of the target using a horizontal slewing shaft,the inner and outer 3D surface profiles of the target were obtained,along with a power spectrum assessment of the entire surface.The experimental results revealed that the respective axial and lateral resolutions of the outer profile measurement were 0.5 and 1.3 nm,while the respective axial and lateral resolutions of the inner profile measurement were 2.0 nm and approximately 400.0 nm.The repeatabilities of the rootmean-square deviation measurements for the outer and inner profiles of the target were 2.6 and 2.4 nm,respectively.We believe our study provides a promising method for the high-resolution and nondestructive co-reference measurement of the inner and outer 3D profiles of laser fusion targets.展开更多
The character of the deformation zone on pair cross rolls is different from that of the regular 4-high mill. Considering comprehensive influences of normal stress and shear stress in rolling direction, width direction...The character of the deformation zone on pair cross rolls is different from that of the regular 4-high mill. Considering comprehensive influences of normal stress and shear stress in rolling direction, width direction and thickness direction, the rolling force calculation model of the PC （pair crossed） hot strip mill is built. Taking the entry stress and the exit stress of strip as the boundary conditions, the longitudinal and transverse distribution of rolling force is worked out by the differential method. Then the total rolling force is calculated, and calculated results are verified by experimental data.展开更多
Different types of urban construction land are different in terms of driving factors for their expansion.Most existing studies on driving forces for urban construction land expansion have considered the construction u...Different types of urban construction land are different in terms of driving factors for their expansion.Most existing studies on driving forces for urban construction land expansion have considered the construction urban land as a whole and have not examined and compared the differentiated driving forces for different types of construction land expansion.This study explored the differentiated driving mechanisms for two types of urban construction land expansion by selecting key driving factors and using spatial econometric regression and geographical detector models.The results show that there are significant differences in the driving forces for expansion between the two types of urban construction land.The driving factors of urban land expansion do not necessarily affect industrial parks.And the factors acting on expansion of both types are different in influence degree.For urban expansion,economic density growth,the value-added growth of tertiary industries,and proximity to urban centers have a negative effect.However,urbanization levels and value-added growth of secondary industries have a positive effect.The explanatory power of these factors is arranged in the following descending order:value-added growth of tertiary industries,value-added change of secondary industries,urban population growth,economic density growth,and proximity to urban centers;road network density has no significant effect.For industrial parks expansion,the value-added growth of secondary industries and road network density has a positive effect,while economic density growth has a negative effect.The explanatory power is arranged in the following descending order:value-added growth of secondary industries,road network density,and economic density growth.The findings can help implement differentiated and refined urban land use management policies.展开更多
In this study, coupled equations of the motion of a particle in a fluid forced vortex were investigated using the differential transformation method （DTM） with the Pad6 approximation and the differential quadrature ...In this study, coupled equations of the motion of a particle in a fluid forced vortex were investigated using the differential transformation method （DTM） with the Pad6 approximation and the differential quadrature method （DO_M）. The significant contribution of the work is the introduction of two new, fast and efficient solutions for a spherical particle in a forced vortex that are improvements over the previous numerical results in the literature. These methods represent approximations with a high degree of accuracy and minimal computational effort for studying the particle motion in a fluid forced vortex. In addition, the velocity profiles （angular and radial） and the position trajectory of a particle in a fluid forced vortex are described in the current study.展开更多
基金supported by the National Natural Science Foundation of China(52327806 and U22A6006).
文摘The high-resolution and nondestructive co-reference measurement of the inner and outer threedimensional(3D)surface profiles of laser fusion targets is difficult to achieve.In this study,we propose a laser differential confocal(LDC)–atomic force probe(AFP)method to measure the inner and outer 3D surface profiles of laser fusion targets at a high resolution.This method utilizes the LDC method to detect the deflection of the AFP and exploits the high spatial resolution of the AFP to enhance the spatial resolution of the outer profile measurement.Nondestructive and co-reference measurements of the inner profile of a target were achieved using the tomographic characteristics of the LDC method.Furthermore,by combining multiple repositionings of the target using a horizontal slewing shaft,the inner and outer 3D surface profiles of the target were obtained,along with a power spectrum assessment of the entire surface.The experimental results revealed that the respective axial and lateral resolutions of the outer profile measurement were 0.5 and 1.3 nm,while the respective axial and lateral resolutions of the inner profile measurement were 2.0 nm and approximately 400.0 nm.The repeatabilities of the rootmean-square deviation measurements for the outer and inner profiles of the target were 2.6 and 2.4 nm,respectively.We believe our study provides a promising method for the high-resolution and nondestructive co-reference measurement of the inner and outer 3D profiles of laser fusion targets.
基金Item Sponsored by ("863"Program) of China National High Technology Research and Development Program(2009AA04Z143)
文摘The character of the deformation zone on pair cross rolls is different from that of the regular 4-high mill. Considering comprehensive influences of normal stress and shear stress in rolling direction, width direction and thickness direction, the rolling force calculation model of the PC （pair crossed） hot strip mill is built. Taking the entry stress and the exit stress of strip as the boundary conditions, the longitudinal and transverse distribution of rolling force is worked out by the differential method. Then the total rolling force is calculated, and calculated results are verified by experimental data.
文摘By a Riccati transformation, we establish some new oscillation criteria which im-prove and generalize some known results in the previous literatures.
基金National Natural Science Foundation of China,No.42071158,No.42130712,No.41801114。
文摘Different types of urban construction land are different in terms of driving factors for their expansion.Most existing studies on driving forces for urban construction land expansion have considered the construction urban land as a whole and have not examined and compared the differentiated driving forces for different types of construction land expansion.This study explored the differentiated driving mechanisms for two types of urban construction land expansion by selecting key driving factors and using spatial econometric regression and geographical detector models.The results show that there are significant differences in the driving forces for expansion between the two types of urban construction land.The driving factors of urban land expansion do not necessarily affect industrial parks.And the factors acting on expansion of both types are different in influence degree.For urban expansion,economic density growth,the value-added growth of tertiary industries,and proximity to urban centers have a negative effect.However,urbanization levels and value-added growth of secondary industries have a positive effect.The explanatory power of these factors is arranged in the following descending order:value-added growth of tertiary industries,value-added change of secondary industries,urban population growth,economic density growth,and proximity to urban centers;road network density has no significant effect.For industrial parks expansion,the value-added growth of secondary industries and road network density has a positive effect,while economic density growth has a negative effect.The explanatory power is arranged in the following descending order:value-added growth of secondary industries,road network density,and economic density growth.The findings can help implement differentiated and refined urban land use management policies.
文摘In this study, coupled equations of the motion of a particle in a fluid forced vortex were investigated using the differential transformation method （DTM） with the Pad6 approximation and the differential quadrature method （DO_M）. The significant contribution of the work is the introduction of two new, fast and efficient solutions for a spherical particle in a forced vortex that are improvements over the previous numerical results in the literature. These methods represent approximations with a high degree of accuracy and minimal computational effort for studying the particle motion in a fluid forced vortex. In addition, the velocity profiles （angular and radial） and the position trajectory of a particle in a fluid forced vortex are described in the current study.
