On the basis of 900-year integration of a global ocean circulation model-LICOM driven by ECMWF reanalysis wind data with uniform 0.5°-grids, a quantitative estimate of the annual and monthly mean water exchange o...On the basis of 900-year integration of a global ocean circulation model-LICOM driven by ECMWF reanalysis wind data with uniform 0.5°-grids, a quantitative estimate of the annual and monthly mean water exchange of the South China Sea （SCS） with its adjacent oceans through 5 straits is obtained. Among them, the annual transport is the largest in the Luzon Strait, then in the Taiwan Strait, and then in the Sunda Shelf, in the Balabac Strait and in the Mindoro Strait in turn, the largest monthly transport variation appears in the Luzon Strait and Sunda shelf. It is shown that the mass transport through the Taiwan Strait is affected by monsoon, while the transport through the Luzon Strait may be associated with the bifurcation position of the North Equatorial Current off the east Philippines shore; the transports in the Luzon Strait and Sunda Shelf are out of phase in direction but well correlated in magnitude. The annual and monthly mean heat and salinity exchange of the SCS through the straits are also calculated and shown to be in phase with the mass transport. The Kuroshio water carries about 0.43 PW heat transport and 151.33 kt/s salinity transport into the SCS, while most of them is carried out of the SCS through the Taiwan Strait and Sunda Shelf annually. The further model integration based on the 900-year integration for another 44 a from 1958 to 2001 driven by real wind data （ERA40 data） shows that the monthly mean mass transport via these straits varies annually with a large variation range, which may be associated with the seasonal and interannual variations in the current field and sea surface height in the SCS. The mean mass transport through the Taiwan Strait, Luzon Strait, Mindoro Strait, Balabac Strait and Sunda Shelf is 2.012×10^6, -4.063×10^6, -0.124×10^6, -0.083×10^6 and 2.258×10^6 m^3/s, respectively.展开更多
Ice crossings have been used for several reasons.First,due to the active development of the Arctic shelf,supplies and minerals are provided and transferred on special transports on the surface of ice covers.Second,ice...Ice crossings have been used for several reasons.First,due to the active development of the Arctic shelf,supplies and minerals are provided and transferred on special transports on the surface of ice covers.Second,ice crossings across rivers are used to reduce the length of transport routes.Traditional methods of increasing the load bearing capacity of ice are ice freezing from above,ice freezing from below,and ice strengthening through a wooden copepod flooring.Practical experience shows that the physical and mechanical properties of ice covers are unreliable and changeable in time and strongly depend on various external factors.Therefore,ice covers should be strengthened through alternative methods.Thus,predicting the bearing capacity of ice crossings and exploring methods for their strengthening are important.In this study,we consider the results of experimental and numerical studies on the bearing and deformation capacity of ice beams upon destruction from pure bending.Under pure bending,ice breaks down in the ice crossing when transports move along it.Tests were carried out with a specified reinforcement scheme.The results of the model experiments were compared with numerical calculations in the ANSYS software package.Experiments on ice beams reinforced with various composite materials were also performed.Destruction of samples in all cases occurred as a result of the formation of extensive cracks in the ice caused by the bending moment in the middle of the beam span.Based on the experimental and numerical research results,the use of a surface reinforcement in ice with various materials can increase the bearing capacity from 65%to 99%for this reinforcement scheme.展开更多
We consider a new subgrid eddy viscosity method based on pressure projection and extrapolated trapezoidal rule for the transient Navier-Stokes equations by using lowest equal-order pair of finite elements. The scheme ...We consider a new subgrid eddy viscosity method based on pressure projection and extrapolated trapezoidal rule for the transient Navier-Stokes equations by using lowest equal-order pair of finite elements. The scheme stabilizes convection dominated problems and ameliorates the restrictive inf-sup compatibility stability. It has some attractive fea- tures including parameter free for the pressure stabilized term and calculations required for higher order derivatives. Moreover, it requires only the solutions of the linear system arising from an Oseen problem per time step and has second order temporal accuracy. The method achieves optimal accuracy with respect to solution regularity.展开更多
基金This work was jointly supported by the National Natural Science Foundation of China under contract No.40376003the National Key Basic Research of China under contract NOs G1999043808 and G2000078502+1 种基金the National Special Projects of China under contract NOs 908-02-01-03 and 2001DIA50041the Knowledge Innovation Frontier Project of SCSIO under contract No.LYQY200310.
文摘On the basis of 900-year integration of a global ocean circulation model-LICOM driven by ECMWF reanalysis wind data with uniform 0.5°-grids, a quantitative estimate of the annual and monthly mean water exchange of the South China Sea （SCS） with its adjacent oceans through 5 straits is obtained. Among them, the annual transport is the largest in the Luzon Strait, then in the Taiwan Strait, and then in the Sunda Shelf, in the Balabac Strait and in the Mindoro Strait in turn, the largest monthly transport variation appears in the Luzon Strait and Sunda shelf. It is shown that the mass transport through the Taiwan Strait is affected by monsoon, while the transport through the Luzon Strait may be associated with the bifurcation position of the North Equatorial Current off the east Philippines shore; the transports in the Luzon Strait and Sunda Shelf are out of phase in direction but well correlated in magnitude. The annual and monthly mean heat and salinity exchange of the SCS through the straits are also calculated and shown to be in phase with the mass transport. The Kuroshio water carries about 0.43 PW heat transport and 151.33 kt/s salinity transport into the SCS, while most of them is carried out of the SCS through the Taiwan Strait and Sunda Shelf annually. The further model integration based on the 900-year integration for another 44 a from 1958 to 2001 driven by real wind data （ERA40 data） shows that the monthly mean mass transport via these straits varies annually with a large variation range, which may be associated with the seasonal and interannual variations in the current field and sea surface height in the SCS. The mean mass transport through the Taiwan Strait, Luzon Strait, Mindoro Strait, Balabac Strait and Sunda Shelf is 2.012×10^6, -4.063×10^6, -0.124×10^6, -0.083×10^6 and 2.258×10^6 m^3/s, respectively.
文摘Ice crossings have been used for several reasons.First,due to the active development of the Arctic shelf,supplies and minerals are provided and transferred on special transports on the surface of ice covers.Second,ice crossings across rivers are used to reduce the length of transport routes.Traditional methods of increasing the load bearing capacity of ice are ice freezing from above,ice freezing from below,and ice strengthening through a wooden copepod flooring.Practical experience shows that the physical and mechanical properties of ice covers are unreliable and changeable in time and strongly depend on various external factors.Therefore,ice covers should be strengthened through alternative methods.Thus,predicting the bearing capacity of ice crossings and exploring methods for their strengthening are important.In this study,we consider the results of experimental and numerical studies on the bearing and deformation capacity of ice beams upon destruction from pure bending.Under pure bending,ice breaks down in the ice crossing when transports move along it.Tests were carried out with a specified reinforcement scheme.The results of the model experiments were compared with numerical calculations in the ANSYS software package.Experiments on ice beams reinforced with various composite materials were also performed.Destruction of samples in all cases occurred as a result of the formation of extensive cracks in the ice caused by the bending moment in the middle of the beam span.Based on the experimental and numerical research results,the use of a surface reinforcement in ice with various materials can increase the bearing capacity from 65%to 99%for this reinforcement scheme.
基金Acknowledgments. The work is supported by the Natural Science Foundation of China （No. 10671154 and No. 11071184） and the National Basic Research Program （No. 2005CB321703）. It is also supported by Sichuan Science and Technology Project （No. 05GG006-006-2） and Science Research Foundation of UESTC.
文摘We consider a new subgrid eddy viscosity method based on pressure projection and extrapolated trapezoidal rule for the transient Navier-Stokes equations by using lowest equal-order pair of finite elements. The scheme stabilizes convection dominated problems and ameliorates the restrictive inf-sup compatibility stability. It has some attractive fea- tures including parameter free for the pressure stabilized term and calculations required for higher order derivatives. Moreover, it requires only the solutions of the linear system arising from an Oseen problem per time step and has second order temporal accuracy. The method achieves optimal accuracy with respect to solution regularity.
