This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phe...This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.展开更多
The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s s...The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s surface,suggesting the Hadean crust was lost due to some processes.We investigated the subduction of one of the possible candidates for the primordial crust,anorthosite and KREEP crust similar to the Moon,which is also considered to have formed from the crystallization of the magma ocean.Similar to the present Earth,the subduction of primordial crust by subduction erosion is expected to be an effective way of eliminating primordial crust from the surface.In this study,the subduction rate of the primordial crust via subduction channels is evaluated by numerical simulations.The subduction channels are located between the subducting slab and the mantle wedge and are comprised of primordial crust materials supplied mainly by subduction erosion.We have found that primordial anorthosite and KREEP crust of up to - 50 km thick at the Earth＇s surface was able to be conveyed to the deep mantle within 0.1-2 Gy by that mechanism.展开更多
Magnetic field design is essential for the operation of Hall thrusters.This study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70.A 2D hybrid PIC-DSMC and channel-wall er...Magnetic field design is essential for the operation of Hall thrusters.This study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70.A 2D hybrid PIC-DSMC and channel-wall erosion model are employed to analyze the plume divergence angle and wall erosion rate,while a Farady probe measurement and laser profilometry system are set up to verify the simulation results.The results demonstrate that the genetic algorithm contributes to reducing the divergence angle of the thruster plumes and alleviating the impact of high-energy particles on the discharge channel wall,reducing the erosion by 5.5%and 2.7%,respectively.Further analysis indicates that the change from a divergent magnetic field to a convergent magnetic field,combined with the upstream shift of the ionization region,contributes to the improving the operation of the Hall thruster.展开更多
The Xiaolangdi Hydro-Project is one of the large projects on the main stem of the Middle Yellow River. It has been operated for more than 10 years, since its impoundment in October, 1999. The reservoir has trapped 2.8...The Xiaolangdi Hydro-Project is one of the large projects on the main stem of the Middle Yellow River. It has been operated for more than 10 years, since its impoundment in October, 1999. The reservoir has trapped 2.833 × 10^9 m3 of sediment, and caused the total erosion of 1.891 × 10^9t in the Lower Yellow River from October, 1999 through October, 2010. Not only the serious atrophied situation of the Lower Yellow River （LYR） has been resuscitating, but also many new phenomena of sediment transport and behaviors of channel re-establishing are coming into being. They are illustrated and discussed in detail in this paper.展开更多
文摘This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.
基金supported partly by KAKENHI 26800237 and 26287105
文摘The primordial crust on the Earth formed from the crystallization of the surface magma ocean during the Hadean.However,geological surveys have found no evidence of rocks dating back to more than 4 Ga on the Earth＇s surface,suggesting the Hadean crust was lost due to some processes.We investigated the subduction of one of the possible candidates for the primordial crust,anorthosite and KREEP crust similar to the Moon,which is also considered to have formed from the crystallization of the magma ocean.Similar to the present Earth,the subduction of primordial crust by subduction erosion is expected to be an effective way of eliminating primordial crust from the surface.In this study,the subduction rate of the primordial crust via subduction channels is evaluated by numerical simulations.The subduction channels are located between the subducting slab and the mantle wedge and are comprised of primordial crust materials supplied mainly by subduction erosion.We have found that primordial anorthosite and KREEP crust of up to - 50 km thick at the Earth＇s surface was able to be conveyed to the deep mantle within 0.1-2 Gy by that mechanism.
基金funded by Shanghai Natural Science Foundation(No.12ZR1414700)。
文摘Magnetic field design is essential for the operation of Hall thrusters.This study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70.A 2D hybrid PIC-DSMC and channel-wall erosion model are employed to analyze the plume divergence angle and wall erosion rate,while a Farady probe measurement and laser profilometry system are set up to verify the simulation results.The results demonstrate that the genetic algorithm contributes to reducing the divergence angle of the thruster plumes and alleviating the impact of high-energy particles on the discharge channel wall,reducing the erosion by 5.5%and 2.7%,respectively.Further analysis indicates that the change from a divergent magnetic field to a convergent magnetic field,combined with the upstream shift of the ionization region,contributes to the improving the operation of the Hall thruster.
基金Project supported by the National Basic Research and Development Program of China(973Program,Grant No.2011CB409901)the"12th Five-Year Plan"to Support Science and Technology Project(Grant No.2012BAB02B01)the Special Funds for Public Welfare Project(Grant No.200901014)
文摘The Xiaolangdi Hydro-Project is one of the large projects on the main stem of the Middle Yellow River. It has been operated for more than 10 years, since its impoundment in October, 1999. The reservoir has trapped 2.833 × 10^9 m3 of sediment, and caused the total erosion of 1.891 × 10^9t in the Lower Yellow River from October, 1999 through October, 2010. Not only the serious atrophied situation of the Lower Yellow River （LYR） has been resuscitating, but also many new phenomena of sediment transport and behaviors of channel re-establishing are coming into being. They are illustrated and discussed in detail in this paper.
