In this study,the water entry of wedges in regular waves is numerically investigated by a two-dimensional in-house numerical code.The numerical model based on the viscous Navier−Stokes(N−S)equations employs a high-ord...In this study,the water entry of wedges in regular waves is numerically investigated by a two-dimensional in-house numerical code.The numerical model based on the viscous Navier−Stokes(N−S)equations employs a high-order different method—the constrained interpolation profile(CIP)method to discretize the convection term.A Volume of Fluid(VOF)-type method,the tangent of hyperbola for interface capturing/slope weighting(THINC/SW)is employed to capture the free surface/interface,and an immersed boundary method is adopted to treat the motion of wedges.The momentum source function derived from the Boussinesq equation is applied as an internal wavemaker to generate regular waves.The accuracy of the numerical model is validated in comparison with experimental results in the literature.The results of water entry in waves are provided in terms of the impact force of wedge,velocity and pressure distributions of fluid.Considerable attention is paid to the effects of wave parameters and the position of wedge impacting the water surface.It is found that the existence of waves significantly influences the velocity and pressure field of fluid and impact force on the wedges.展开更多
Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally si...Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally sintered at 1 000 ℃. By analyzing the thermogravimetric behavior of the MCMB and SFMP powders, their volume shrinkage and weight loss during sintering and the bulk density and flexural strengths of their sintered bulks, it was found that the smaller sizes and the richer β-resin contents of SFMP ha）re facilitated formation of sintered bulks with more compact isotropic structure and higher flexural strengths than MCMB. Because of the filling and bonding effects of SFMP on MCMB bulks, addition of SFMP, albeit a little, can greatly increase the flexural strengths of sintered bulks of MCMB. However, adding MCMB, even a slight amount, into SFMP can severely impair the flexural strength of sintered bulks. This might be attributed to both the crack initiation along the boundaries between MCMB and SFMP and the formation of layered texture of MCMB sphere.展开更多
Based on the background of the second rural land reform in China Taiwan, we analyzed financial support measures and their effects. It comes to the insight into financial support for rural land circulation in China Tai...Based on the background of the second rural land reform in China Taiwan, we analyzed financial support measures and their effects. It comes to the insight into financial support for rural land circulation in China Taiwan for the new round of rural land reform in China mainland. It is proposed to: (i) put forth effort on rural infrastructure construction with financial special fund as major support and credit fund from policy bank as supplementary support; (ii) improve rural land evaluation, registration and guarantee systems and set up special loan for land circulation, to solve the problem of shortage of fund for farmers purchasing land; (iii) grant operating loans for rural large planting and breeding farmer households, to accelerate land circulation becoming effective; (iv) establish development fund for agriculture, farmers and rural areas, to ensure sustainable input into rural areas.展开更多
基金supported by Foundation of Zhejiang Institute of Hydraulic and Estuary(Grant No.Haian A18003)the Science and Technology Plan Projects of Zhejiang water(Grant No.RB1803)+1 种基金Zhejiang Provincial Natural Science Foundation(Grant Nos.LQ19E090004 and LQ16E090004)the Science and Technology Plan Projects of Zhejiang Province(Grant No.2018F10026)and Tang Scholar.
文摘In this study,the water entry of wedges in regular waves is numerically investigated by a two-dimensional in-house numerical code.The numerical model based on the viscous Navier−Stokes(N−S)equations employs a high-order different method—the constrained interpolation profile(CIP)method to discretize the convection term.A Volume of Fluid(VOF)-type method,the tangent of hyperbola for interface capturing/slope weighting(THINC/SW)is employed to capture the free surface/interface,and an immersed boundary method is adopted to treat the motion of wedges.The momentum source function derived from the Boussinesq equation is applied as an internal wavemaker to generate regular waves.The accuracy of the numerical model is validated in comparison with experimental results in the literature.The results of water entry in waves are provided in terms of the impact force of wedge,velocity and pressure distributions of fluid.Considerable attention is paid to the effects of wave parameters and the position of wedge impacting the water surface.It is found that the existence of waves significantly influences the velocity and pressure field of fluid and impact force on the wedges.
文摘Mesocarbon microbeads （MCMB） and super fine mesophase powder （SFMP） were prepared firstly from a coal tar pitch and then hot-condensed into high-density isotropic carbon （HDIC） bulks under 160 MPa and finally sintered at 1 000 ℃. By analyzing the thermogravimetric behavior of the MCMB and SFMP powders, their volume shrinkage and weight loss during sintering and the bulk density and flexural strengths of their sintered bulks, it was found that the smaller sizes and the richer β-resin contents of SFMP ha）re facilitated formation of sintered bulks with more compact isotropic structure and higher flexural strengths than MCMB. Because of the filling and bonding effects of SFMP on MCMB bulks, addition of SFMP, albeit a little, can greatly increase the flexural strengths of sintered bulks of MCMB. However, adding MCMB, even a slight amount, into SFMP can severely impair the flexural strength of sintered bulks. This might be attributed to both the crack initiation along the boundaries between MCMB and SFMP and the formation of layered texture of MCMB sphere.
基金Supported by Soft Science Project of Science and Technology Commission of Chongqing Municipality (cstc2011cx-rkxA011)
文摘Based on the background of the second rural land reform in China Taiwan, we analyzed financial support measures and their effects. It comes to the insight into financial support for rural land circulation in China Taiwan for the new round of rural land reform in China mainland. It is proposed to: (i) put forth effort on rural infrastructure construction with financial special fund as major support and credit fund from policy bank as supplementary support; (ii) improve rural land evaluation, registration and guarantee systems and set up special loan for land circulation, to solve the problem of shortage of fund for farmers purchasing land; (iii) grant operating loans for rural large planting and breeding farmer households, to accelerate land circulation becoming effective; (iv) establish development fund for agriculture, farmers and rural areas, to ensure sustainable input into rural areas.
