We take Chongqing as an example to analyze reasons for rural population gradient transfer from such factors as social system,industrial development,urban planning,and living costs.Finally,we present four policies and ...We take Chongqing as an example to analyze reasons for rural population gradient transfer from such factors as social system,industrial development,urban planning,and living costs.Finally,we present four policies and suggestions,including promoting urban construction,increasing investment in rural areas,pushing forward construction of labor market,and bringing safeguarding function into full play.展开更多
The heat transfer coefficient h caused by blowing affects the heat transfer of fiber greatly. Especially,unsymmetrical blowing forms the unsymmetrical temperature gradient on the fiber cross.section. Based on the resu...The heat transfer coefficient h caused by blowing affects the heat transfer of fiber greatly. Especially,unsymmetrical blowing forms the unsymmetrical temperature gradient on the fiber cross.section. Based on the results of spinning simulation by computer, the changes of heat transfer coefficient on the cross-section along the spinning line and the effects on distributions of temperature gradients were discussedl It is showed that for the spinning simulation of hollow fiber under strong blowing condition, the heat transfer coetticient should bemodified as: h=0.437×10-4[ G/Vρ ( R2/ R2-n2 ) ] -o.333(V2+ 64( VYsin (θ))2)0.展开更多
The nucleation can be enhanced by decreasing the superheat of molten steel, thus reducing temperature gradient on the solidification front can retard the growth of columnar crystals and enlarge the equiaxed zone in co...The nucleation can be enhanced by decreasing the superheat of molten steel, thus reducing temperature gradient on the solidification front can retard the growth of columnar crystals and enlarge the equiaxed zone in continuous casting strand. The billets with equiaxed zone more than 90% were cast with a combined mould and the heat flux was measured. The heat transfer of the combined mould and traditional mould was compared. The resuits show that under same casting conditions, the temperature gradient on the solidification front in the combined mould is smaller than that in traditional mould at a distance within 0-150 mm from the meniscus.展开更多
Nanofluidics in hydrophilic nanopores is a common issue in many natural and industrial processes. Among all,the mass transport of nanofluidics is most concerned. Besides that, the heat transfer of a fluid flow in nano...Nanofluidics in hydrophilic nanopores is a common issue in many natural and industrial processes. Among all,the mass transport of nanofluidics is most concerned. Besides that, the heat transfer of a fluid flow in nano or micro channels is always considered with adding nanoparticles into the flow, so as to enhance the heat transfer by convection between the fluid and the surface. However, for some applications with around 1 nm channels such as nano filtration or erosion of rocks, there should be no nanoparticles included. Hence, it is necessary to figure out the heat transfer mechanism in the single phase nanofluidics. Via non-equilibrium molecular dynamics simulations, we revealed the heat transfer inside nanofluidics and the one between fluid and walls by setting simulation into extremely harsh condition. It was found that the heat was conducted by molecular motion without temperature gradient in the area of low viscous heat, while it was transferred to the walls by increasing the temperature of fluids. If the condition back to normal, it was found that the viscous heat of nanofluidics could be easily removed by the fluid-wall temperature drop of less than 1 K.展开更多
Reconstructing the distribution of optical parameters in the participating medium based on the frequency-domain radiative transfer equation （FD-RTE） to probe the internal structure of the medium is investigated in t...Reconstructing the distribution of optical parameters in the participating medium based on the frequency-domain radiative transfer equation （FD-RTE） to probe the internal structure of the medium is investigated in the present work. The forward model of FD-RTE is solved via the finite volume method （FVM）. The regularization term formatted by the generalized Gaussian Markov random field model is used in the objective function to overcome the ill-posed nature of the inverse problem. The multi-start conjugate gradient （MCG） method is employed to search the minimum of the objective function and increase the efficiency of convergence. A modified adjoint differentiation technique using the collimated radiative intensity is developed to calculate the gradient of the objective function with respect to the optical parameters. All simulation results show that the proposed reconstruction algorithm based on FD-RTE can obtain the accurate distributions of absorption and scattering coefficients. The reconstructed images of the scattering coefficient have less errors than those of the absorption coefficient, which indicates the former are more suitable to probing the inner structure.展开更多
This paper is concerned with the optimal design of an obstacle located in the viscous and incompressible fluid which is driven by the steady-state Oseen equations with thermal effects. The structure of shape gradient ...This paper is concerned with the optimal design of an obstacle located in the viscous and incompressible fluid which is driven by the steady-state Oseen equations with thermal effects. The structure of shape gradient of the cost functional is derived by applying the differentiability of a minimax formulation involving a Lagrange functional with a space parametrization technique. A gradient type algorithm is employed to the shape optimization problem. Numerical examples indicate that our theory is useful for practical purpose and the proposed algorithm is feasible.展开更多
The excited state intramolecular proton transfer of four derivatives(FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated.The geometries of different substituents are optimized to study the substituent effects on ...The excited state intramolecular proton transfer of four derivatives(FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated.The geometries of different substituents are optimized to study the substituent effects on proton transfer.The mechanism of hydrogen bond enhancement is qualitatively elucidated by comparing the infrared spectra, the reduced density gradient, and the frontier molecular orbitals.The calculated electronic spectra are consistent with the experimental results.To quantify the proton transfer, the potential energy curves(PECs) of the four derivatives in S0 and S1 states are scanned.It is concluded that the ability of proton transfer follows the order: FM > BFM > BFBC > CCM.展开更多
基金Supported by Foundation Project of Chongqing Education College
文摘We take Chongqing as an example to analyze reasons for rural population gradient transfer from such factors as social system,industrial development,urban planning,and living costs.Finally,we present four policies and suggestions,including promoting urban construction,increasing investment in rural areas,pushing forward construction of labor market,and bringing safeguarding function into full play.
文摘The heat transfer coefficient h caused by blowing affects the heat transfer of fiber greatly. Especially,unsymmetrical blowing forms the unsymmetrical temperature gradient on the fiber cross.section. Based on the results of spinning simulation by computer, the changes of heat transfer coefficient on the cross-section along the spinning line and the effects on distributions of temperature gradients were discussedl It is showed that for the spinning simulation of hollow fiber under strong blowing condition, the heat transfer coetticient should bemodified as: h=0.437×10-4[ G/Vρ ( R2/ R2-n2 ) ] -o.333(V2+ 64( VYsin (θ))2)0.
文摘The nucleation can be enhanced by decreasing the superheat of molten steel, thus reducing temperature gradient on the solidification front can retard the growth of columnar crystals and enlarge the equiaxed zone in continuous casting strand. The billets with equiaxed zone more than 90% were cast with a combined mould and the heat flux was measured. The heat transfer of the combined mould and traditional mould was compared. The resuits show that under same casting conditions, the temperature gradient on the solidification front in the combined mould is smaller than that in traditional mould at a distance within 0-150 mm from the meniscus.
基金Supported by the National Basic Research Program of China(2015CB655301)the National Natural Science Foundation of China(21506091)+2 种基金the Jiangsu Natural Science Foundations(BK20150944)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Nanofluidics in hydrophilic nanopores is a common issue in many natural and industrial processes. Among all,the mass transport of nanofluidics is most concerned. Besides that, the heat transfer of a fluid flow in nano or micro channels is always considered with adding nanoparticles into the flow, so as to enhance the heat transfer by convection between the fluid and the surface. However, for some applications with around 1 nm channels such as nano filtration or erosion of rocks, there should be no nanoparticles included. Hence, it is necessary to figure out the heat transfer mechanism in the single phase nanofluidics. Via non-equilibrium molecular dynamics simulations, we revealed the heat transfer inside nanofluidics and the one between fluid and walls by setting simulation into extremely harsh condition. It was found that the heat was conducted by molecular motion without temperature gradient in the area of low viscous heat, while it was transferred to the walls by increasing the temperature of fluids. If the condition back to normal, it was found that the viscous heat of nanofluidics could be easily removed by the fluid-wall temperature drop of less than 1 K.
基金Project supported by the National Natural Science Foundation of China(Grant No.51476043)the Major National Scientific Instruments and Equipment Development Special Foundation of China(Grant No.51327803)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.51121004)
文摘Reconstructing the distribution of optical parameters in the participating medium based on the frequency-domain radiative transfer equation （FD-RTE） to probe the internal structure of the medium is investigated in the present work. The forward model of FD-RTE is solved via the finite volume method （FVM）. The regularization term formatted by the generalized Gaussian Markov random field model is used in the objective function to overcome the ill-posed nature of the inverse problem. The multi-start conjugate gradient （MCG） method is employed to search the minimum of the objective function and increase the efficiency of convergence. A modified adjoint differentiation technique using the collimated radiative intensity is developed to calculate the gradient of the objective function with respect to the optical parameters. All simulation results show that the proposed reconstruction algorithm based on FD-RTE can obtain the accurate distributions of absorption and scattering coefficients. The reconstructed images of the scattering coefficient have less errors than those of the absorption coefficient, which indicates the former are more suitable to probing the inner structure.
文摘This paper is concerned with the optimal design of an obstacle located in the viscous and incompressible fluid which is driven by the steady-state Oseen equations with thermal effects. The structure of shape gradient of the cost functional is derived by applying the differentiability of a minimax formulation involving a Lagrange functional with a space parametrization technique. A gradient type algorithm is employed to the shape optimization problem. Numerical examples indicate that our theory is useful for practical purpose and the proposed algorithm is feasible.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874241,11847224,and 11804195)the Shandong Province Higher Educational Science and Technology Program,China(Grant No.J15LJ03)+1 种基金the Taishan Scholar Project of Shandong Province,China,China Post-Doctoral Foundation(Grant No.2018M630796)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2018BA034)
文摘The excited state intramolecular proton transfer of four derivatives(FM, BFM, BFBC, CCM) of 3-hydroxychromone is investigated.The geometries of different substituents are optimized to study the substituent effects on proton transfer.The mechanism of hydrogen bond enhancement is qualitatively elucidated by comparing the infrared spectra, the reduced density gradient, and the frontier molecular orbitals.The calculated electronic spectra are consistent with the experimental results.To quantify the proton transfer, the potential energy curves(PECs) of the four derivatives in S0 and S1 states are scanned.It is concluded that the ability of proton transfer follows the order: FM > BFM > BFBC > CCM.
