In order to explore the advantages of the triangular weir fishway and the influence of the angle of the triangular weir fishway on fish migration,this paper simulates the internal flow field and free surface of the fi...In order to explore the advantages of the triangular weir fishway and the influence of the angle of the triangular weir fishway on fish migration,this paper simulates the internal flow field and free surface of the fishway by using large eddy simulation(LES)and volume of fluid(VOF)method,respectively,and analyzes the hydraulic characteristics of the triangular weir at the three angles,where for the analysis of turbulent structure,omega(Ω)eddy identification is also used.And based on the analysis results,the length of the pool chamber and the height of obstacles were changed to obtain a more stable flow regime.The results show that the main flow is obvious,the turbulent kinetic energy distribution is regular and small in value,and the angle has an effect on the return flow.The vortex structure mainly existed in the mainstream area with high flow velocity,the air-liquid interface and the porosity,and was distributed transversely.90°triangular weir had the largest vortex structure,and 105°triangular weir had the smallest.75°triangular weir fishway could effectively attenuate the energy of the main stream,and the area of high velocity flow was small,which made the migratory conditions more favorable.Adding obstructions to the mainstem area can reduce flow velocity and turbulent kinetic energy.The triangular weir structure can improve the flow structure of the fishway,and the different angles and water depths provide a variety of flow conditions for a variety of fish migrations,providing new ideas for the fishway.展开更多
The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs d...The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs during near-solid-melt treatment(NSMT)process even in the absence of Mn,because of the high saturation of Fe in the melt.Furthermore,in the NSMT process,even a small amount of Mn addition can lead to a sharp deposition of Mn atoms.The NSMT process can increase the growth rate of the Fe-rich particles,and then accelerate their sinking movement.Nevertheless,the addition of Mn hinders the coarsening process of Fe-rich particles.Besides,the corrosion susceptibility of the alloys is mainly affected by the solubility of Fe,which can be significantly reduced by Mn addition.Moreover,the presence of more Fe-rich particles does not necessarily increase the corrosion susceptibility of the alloy.Consequently,in the refining process of Mg−Mn alloys made from magnesium scrap,on the basis of NSMT process and adding an appropriate Mn content(about 0.5 wt.%),the purity of the melt can be improved,thereby obtaining an alloy with excellent corrosion resistance.展开更多
This work successfully developed an energy- saving glass with wavelength selectivity. The glass is composed of a SiO2 substrate and two layers of three- dimensional photonic crystals. Each crystal is composed of ident...This work successfully developed an energy- saving glass with wavelength selectivity. The glass is composed of a SiO2 substrate and two layers of three- dimensional photonic crystals. Each crystal is composed of identical and transparent polystyrene spheres after their self-assembling. The glass then possesses dual photonic band gaps in the near-infrared region to suppress penetration of thermal radiation. Experimental results show that the energy-saving glass decreases temperature increment in a mini-house. Moreover, the temperature after thermal equilibrium is lower than that inside a counterpart using ordinary glass.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52069009).
文摘In order to explore the advantages of the triangular weir fishway and the influence of the angle of the triangular weir fishway on fish migration,this paper simulates the internal flow field and free surface of the fishway by using large eddy simulation(LES)and volume of fluid(VOF)method,respectively,and analyzes the hydraulic characteristics of the triangular weir at the three angles,where for the analysis of turbulent structure,omega(Ω)eddy identification is also used.And based on the analysis results,the length of the pool chamber and the height of obstacles were changed to obtain a more stable flow regime.The results show that the main flow is obvious,the turbulent kinetic energy distribution is regular and small in value,and the angle has an effect on the return flow.The vortex structure mainly existed in the mainstream area with high flow velocity,the air-liquid interface and the porosity,and was distributed transversely.90°triangular weir had the largest vortex structure,and 105°triangular weir had the smallest.75°triangular weir fishway could effectively attenuate the energy of the main stream,and the area of high velocity flow was small,which made the migratory conditions more favorable.Adding obstructions to the mainstem area can reduce flow velocity and turbulent kinetic energy.The triangular weir structure can improve the flow structure of the fishway,and the different angles and water depths provide a variety of flow conditions for a variety of fish migrations,providing new ideas for the fishway.
基金Project(2016YFB0301100)supported by the National Key Research and Development Program of ChinaProject(2018CDJDCD0001)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs during near-solid-melt treatment(NSMT)process even in the absence of Mn,because of the high saturation of Fe in the melt.Furthermore,in the NSMT process,even a small amount of Mn addition can lead to a sharp deposition of Mn atoms.The NSMT process can increase the growth rate of the Fe-rich particles,and then accelerate their sinking movement.Nevertheless,the addition of Mn hinders the coarsening process of Fe-rich particles.Besides,the corrosion susceptibility of the alloys is mainly affected by the solubility of Fe,which can be significantly reduced by Mn addition.Moreover,the presence of more Fe-rich particles does not necessarily increase the corrosion susceptibility of the alloy.Consequently,in the refining process of Mg−Mn alloys made from magnesium scrap,on the basis of NSMT process and adding an appropriate Mn content(about 0.5 wt.%),the purity of the melt can be improved,thereby obtaining an alloy with excellent corrosion resistance.
文摘This work successfully developed an energy- saving glass with wavelength selectivity. The glass is composed of a SiO2 substrate and two layers of three- dimensional photonic crystals. Each crystal is composed of identical and transparent polystyrene spheres after their self-assembling. The glass then possesses dual photonic band gaps in the near-infrared region to suppress penetration of thermal radiation. Experimental results show that the energy-saving glass decreases temperature increment in a mini-house. Moreover, the temperature after thermal equilibrium is lower than that inside a counterpart using ordinary glass.
