The leaf-vein drip irrigation emitter is a new type of drip emitter based on a bionic structure able to support shunting,sharp turns,and increased dissipation.In the present work,the results of twenty-five tests execu...The leaf-vein drip irrigation emitter is a new type of drip emitter based on a bionic structure able to support shunting,sharp turns,and increased dissipation.In the present work,the results of twenty-five tests executed in the framework of an orthogonal design strategy are presented in order to clarify the influence of the geometrical parameters of the flow channel on the hydraulic characteristics of such emitter.The corresponding flow index and head loss coefficient are determined through numerical simulations and model testing.The results show that the flow index of the flow channel is 0.4970∼0.5461,which corresponds to good hydraulic performances.The head loss coefficient of the flow channel is 572.74∼3933.05,which in turn indicates a good energy dissipation effect.The order of influence of the leaf vein flow channel parameters on the flow index can be represented in a synthetic way as a>b>c>d>e,where(a)is the width of the inlet,(b)is the horizontal distance of the front water inlet,(c)is the vertical distance of the inner edge of the front end,(d)is the horizontal distance of the rear water outlet and(e)is the vertical distance of the outer edge of the front end.The flow index increases with d,decreases with a,first decreases,and then increases with b,and first increases and then decreases with the increase of c and e.The coefficient(R^(2))of the fitted model related to geometric parameters and flow index is 0.9986-0.9999.The relative errors among experimental testing,simulation calculation and predictive estimates are shown to be less than 5%.展开更多
The bionic structure drip irrigation emitter(BSDE)is a new-type emitter,by which better hydraulic performances can be obtained.In the present work,twenty-five sets of orthogonal test schemes were implemented to analyz...The bionic structure drip irrigation emitter(BSDE)is a new-type emitter,by which better hydraulic performances can be obtained.In the present work,twenty-five sets of orthogonal test schemes were implemented to analyze the influence of the geometric parameters of the flow channel on the hydraulic characteristics and energy dissipation efficiency of this emitter.Through numerical simulations and verification tests,the flow index and energy dissipation coefficient were obtained.According to the results,the flow index of the BSDE is 0.4757-0.5067.The energy dissipation coefficient under the pressure head of 5-15 m is 584-1701.The verification test has shown that the relative errors among measured values,simulated values and estimated values are less than 3%,which indicates that the flow index can be estimated reliably.展开更多
The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens'living standards.However,railway construction in seasonally frozen soil ...The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens'living standards.However,railway construction in seasonally frozen soil areas is often faced with frost heave,leading to uneven subgrades which seriously threaten traffic safety.This article summarizes extant research results on frost heave mechanism,frost heave factors,and anti-frost measures of railway subgrades in seasonally frozen soil areas.展开更多
The permafrost of Mohe County and its suburbs in the Daxing′an Mountains has been influenced by the urbanization.Remote sensing,GIS technology and numerical simulation was used to study the temperature variations of ...The permafrost of Mohe County and its suburbs in the Daxing′an Mountains has been influenced by the urbanization.Remote sensing,GIS technology and numerical simulation was used to study the temperature variations of permafrost with the changes in surface vegetation that cover Mohe County and suburban areas,and the law of permafrost degradation on the study area was analyzed.The research results show that the urban area of the study area increased 114.42%from 2000 to 2016,and the urbanization process is continuing to accelerate.The Normalized Difference Vegetation Index map of 2017 in Mohe County and its suburbs was studied and the maximum proportion of vegetation coverage was different in the four seasons.The numerical calculation model results show that the permafrost temperature change in the study area cyclically fluctuates in a cosine form.The annual variation curve of permafrost temperature gradually decreased and its accompanying phase lag increased with depth.The annual temperature change value with the different depths of the town was greater than the natural ground.The maximum permafrost thawing depths of the town and natural ground were 4.2 m and 2.82 m in 50 a,and the degradation rates of the two permafrost are,respectively,0.88 cm/a and 0.46 cm/a.These results show that urbanization has accelerated the degradation of permafrost.展开更多
In the present study,two new Co(Ⅱ)-based coordination polymers(CPs)with chemical formulas of{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)_(3)]·2H_(2)O}n(1)and{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)]·2DMF·3H_(2)O}n(2)have been...In the present study,two new Co(Ⅱ)-based coordination polymers(CPs)with chemical formulas of{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)_(3)]·2H_(2)O}n(1)and{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)]·2DMF·3H_(2)O}n(2)have been successfully prepared by the reaction of Co(NO_(3))_(2)·6H_(2)O withπ-electron-rich polycarboxylate aryl ether ligand 5,5’-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid(H5L)under different solvothermal reaction conditions.Both CPs have been studied via single-crystal X-day diffraction,powder X-ray diffraction(PXRD)and thermogravimetric analysis(TGA).The photophysical studies indicated that complex 2 with good water stability is a potential semiconductive material,which could be applied for the degradation of methylene blue(MB)under UV light irradiation and exhibit good stability and recyclability.展开更多
基金supported by the Basic Scientific Research Fund of Heilongjiang Provincial Universities(2021-KYYWF-0050).
文摘The leaf-vein drip irrigation emitter is a new type of drip emitter based on a bionic structure able to support shunting,sharp turns,and increased dissipation.In the present work,the results of twenty-five tests executed in the framework of an orthogonal design strategy are presented in order to clarify the influence of the geometrical parameters of the flow channel on the hydraulic characteristics of such emitter.The corresponding flow index and head loss coefficient are determined through numerical simulations and model testing.The results show that the flow index of the flow channel is 0.4970∼0.5461,which corresponds to good hydraulic performances.The head loss coefficient of the flow channel is 572.74∼3933.05,which in turn indicates a good energy dissipation effect.The order of influence of the leaf vein flow channel parameters on the flow index can be represented in a synthetic way as a>b>c>d>e,where(a)is the width of the inlet,(b)is the horizontal distance of the front water inlet,(c)is the vertical distance of the inner edge of the front end,(d)is the horizontal distance of the rear water outlet and(e)is the vertical distance of the outer edge of the front end.The flow index increases with d,decreases with a,first decreases,and then increases with b,and first increases and then decreases with the increase of c and e.The coefficient(R^(2))of the fitted model related to geometric parameters and flow index is 0.9986-0.9999.The relative errors among experimental testing,simulation calculation and predictive estimates are shown to be less than 5%.
基金This work was supported by the Basic Scientific Research Fund of Heilongjiang Provincial Universities(2020-KYYWF-1042).
文摘The bionic structure drip irrigation emitter(BSDE)is a new-type emitter,by which better hydraulic performances can be obtained.In the present work,twenty-five sets of orthogonal test schemes were implemented to analyze the influence of the geometric parameters of the flow channel on the hydraulic characteristics and energy dissipation efficiency of this emitter.Through numerical simulations and verification tests,the flow index and energy dissipation coefficient were obtained.According to the results,the flow index of the BSDE is 0.4757-0.5067.The energy dissipation coefficient under the pressure head of 5-15 m is 584-1701.The verification test has shown that the relative errors among measured values,simulated values and estimated values are less than 3%,which indicates that the flow index can be estimated reliably.
基金the Foundation for Excellent Youth Scholars of"Northwest Institute of Eco-Environment and Resources",CAS(grant number:FEYS2019002)the Research Project of State Key Laboratory of Frozen Soil Engineering(grant number:SKLFSE-ZQ-52)the Open Project of State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(grant number:KF2020-02)。
文摘The building of railways on seasonally frozen ground is inevitable as China pursues economic development and the improvement of its citizens'living standards.However,railway construction in seasonally frozen soil areas is often faced with frost heave,leading to uneven subgrades which seriously threaten traffic safety.This article summarizes extant research results on frost heave mechanism,frost heave factors,and anti-frost measures of railway subgrades in seasonally frozen soil areas.
基金Nation Natural Science Foundation of China under Grant No.41071049Project of the State Key Laboratory Frozen Soil Engineering of CAS under Grant No.SKLFSE201802Project of 2017 Harbin Applied Technology Research and Development under Grant No.2017RAXXJ031。
文摘The permafrost of Mohe County and its suburbs in the Daxing′an Mountains has been influenced by the urbanization.Remote sensing,GIS technology and numerical simulation was used to study the temperature variations of permafrost with the changes in surface vegetation that cover Mohe County and suburban areas,and the law of permafrost degradation on the study area was analyzed.The research results show that the urban area of the study area increased 114.42%from 2000 to 2016,and the urbanization process is continuing to accelerate.The Normalized Difference Vegetation Index map of 2017 in Mohe County and its suburbs was studied and the maximum proportion of vegetation coverage was different in the four seasons.The numerical calculation model results show that the permafrost temperature change in the study area cyclically fluctuates in a cosine form.The annual variation curve of permafrost temperature gradually decreased and its accompanying phase lag increased with depth.The annual temperature change value with the different depths of the town was greater than the natural ground.The maximum permafrost thawing depths of the town and natural ground were 4.2 m and 2.82 m in 50 a,and the degradation rates of the two permafrost are,respectively,0.88 cm/a and 0.46 cm/a.These results show that urbanization has accelerated the degradation of permafrost.
文摘In the present study,two new Co(Ⅱ)-based coordination polymers(CPs)with chemical formulas of{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)_(3)]·2H_(2)O}n(1)and{[Co_(3)(μ_(3)-OH)(L)(H_(2)O)]·2DMF·3H_(2)O}n(2)have been successfully prepared by the reaction of Co(NO_(3))_(2)·6H_(2)O withπ-electron-rich polycarboxylate aryl ether ligand 5,5’-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid(H5L)under different solvothermal reaction conditions.Both CPs have been studied via single-crystal X-day diffraction,powder X-ray diffraction(PXRD)and thermogravimetric analysis(TGA).The photophysical studies indicated that complex 2 with good water stability is a potential semiconductive material,which could be applied for the degradation of methylene blue(MB)under UV light irradiation and exhibit good stability and recyclability.