Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin.It is difficult to identify the sources and to quantify th...Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin.It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source.In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps(S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin.Chemical oxygen demand(COD) and ammonia nitrogen(NH 3-N) loads were estimated.Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively.NH 3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively.Point source pollution was stronger than nonpoint source pollution in the study area at present.The water quality of upstream was better than that of downstream of the rivers and cities.It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin.The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating.展开更多
Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological im...Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological impact evaluation. In this study, throughfall, stemflow and interception were measured in a pure Larix principis-rupprechtii Mayr.（larch） plantation in the Liupan Mountains of northwestern China during the growing season（May–October） of 2015, and simulated using a revised Gash model. During the study period, the total precipitation was 499.0 mm; corresponding total throughfall, stemflow and canopy interception were 410.3, 2.0 and 86.7 mm,accounting for 82.2, 0.4 and 17.4% of the total precipitation, respectively. With increasing rainfall, the canopy interception ratio of individual rainfall events decreased initially and then tended to stabilize. Within the study period, the simulated total canopy interception, throughfall and stemflow were 2.2 mm lower, 2.5 mm higher and 0.3 mm lower than their measured values, with a relative error of 2.5, 0.6 and 15.0%, respectively. As quantified by the model, canopy interception loss（79%） mainly consisted of interception caused by canopy adsorption, while the proportions of additional interception and trunk interception were small. The revised Gash model was highly sensitive to the parameter of canopy storage capacity,followed by the parameters of canopy density and mean rainfall intensity, but less sensitive to the parameters of mean evaporation rate, trunk storage capacity, and stemflow ratio. The revised Gash model satisfactorily simulated the total canopy interception of the larch plantation within the growing season but was less accurate for some individual rainfall events, indicating that some flaws exist in the model structure. Further measures to improve the model’s ability in simulating the interception of individual rainfall events were suggested.展开更多
Rivers in the Liaohe River Estuary area have been seriously polluted by discharges of wastewater containing petroleum pol- lutants and nutrients. In this paper, The Enhanced Stream Water Quality Model （QUAL2K） and i...Rivers in the Liaohe River Estuary area have been seriously polluted by discharges of wastewater containing petroleum pol- lutants and nutrients. In this paper, The Enhanced Stream Water Quality Model （QUAL2K） and its revised model as well as One-dimensional Tide Mean Model （1D model） were applied to predict and assess the water quality of the tidal fiver reach of the Liaohe River Estuary. Dissolved oxygen （DO）, biochemical oxygen demand （BODs）, ammonia nitrogen （NH3-N） and total phosphorus （TP） were chosen as water quality indices in the two model simulations. The modelled results show that the major reasons for degraded rivers remain petroleum and non-point source pollution. Tidal water also has a critical effect on the variation of water quality. The sensitivity analysis identifies that flow rate, point load and diffuse load are the most sensitive parameters for the four water quality indices in the revised QUAL2K simulation. Uncertainty analysis based on a Monte Carlo simulation gives the probability distribution of the four wa- ter quality indices at two locations （6.50 km and 44.84 km from the river mouth）. The statistical outcomes indicate that the observed data fall within the 90% confidence intervals at all sites measured, and show that the revised QUAL2K gives better results in simulating the water quality of a tidal fiver.展开更多
The research is motivated by the ongoing the electromagnetic continuous casting of molten metal. The revised k-ε model considering the effect of magnetic field application was derived. The specific model equations fo...The research is motivated by the ongoing the electromagnetic continuous casting of molten metal. The revised k-ε model considering the effect of magnetic field application was derived. The specific model equations for the electromagnetic braking were used to calculate the velocity distribution in the continuous casting mold of steel. The results show that the revised k-ε model considering the effect of magnetic field application tends to suppress the production of turbulence and difference between the conventional and revised k-e model is small.展开更多
Quasi-elastic neutron scattering(QENS) has many applications that are directly related to the development of highperformance functional materials and biological macromolecules, especially those containing some water. ...Quasi-elastic neutron scattering(QENS) has many applications that are directly related to the development of highperformance functional materials and biological macromolecules, especially those containing some water. The analysis method of QENS spectra data is important to obtain parameters that can explain the structure of materials and the dynamics of water. In this paper, we present a revised jump-diffusion and rotation-diffusion model(rJRM) used for QENS spectra data analysis. By the rJRM, the QENS spectra from a pure magnesium-silicate-hydrate(MSH) sample are fitted well for the Q range from 0.3 ^(-1) to 1.9 ^(-1) and temperatures from 210 K up to 280 K. The fitted parameters can be divided into two kinds. The first kind describes the structure of the MSH sample, including the ratio of immobile water(or bound water) C and the confining radius of mobile water a_0. The second kind describes the dynamics of confined water in pores contained in the MSH sample, including the translational diffusion coefficient Dt, the average translational residence timeτ0, the rotational diffusion coefficient D_r, and the mean squared displacement(MSD) u^2. The r JRM is a new practical method suitable to fit QENS spectra from porous materials, where hydrogen atoms appear in both solid and liquid phases.展开更多
In order to investigate the sand mold strength after the aeration sand filling-high pressure squeeze moldingprocess,a tree-dimentional(3D)numerical simulation was introduced.The commercial finite element method(FEM)so...In order to investigate the sand mold strength after the aeration sand filling-high pressure squeeze moldingprocess,a tree-dimentional(3D)numerical simulation was introduced.The commercial finite element method(FEM)software ABAQUScombined with a revised Drucker-Prager/Cap model was used to simulate the squeeze compaction process.Additionally,the sand bulk density after the aeration sand filling process was tested by a specially designed experiment,which divided the whole sand bulk in the molding chamber into5x9regions and it was used as the input to simulate the squeeze process.During the simulation process,the uniform modeling simulation and the patition modeling simulation methods were used a d the3D numercal simulation results were compared with correlative benchmark testings.From the3D numerica simulation results,it can be concluded that the uniform sand bulk density distribution can obtain a high quality sandmold and the revised Drncker-Pager/Cap model is suitable for handling the situation with the complex paaern.The3D numerical simulation results can predict well the sand mold strength distribution and can be used as guidelines for the production practice.展开更多
Revision is a complex,yet important phase in writing to improve the quality of a text.Some revision models are created to explain its components and the ways these components work.However,analysis of available models ...Revision is a complex,yet important phase in writing to improve the quality of a text.Some revision models are created to explain its components and the ways these components work.However,analysis of available models shows that they are proposed mainly for expert writers,who can complete the complex revision process individually,without the need of support or feedback.Most of the available revision models also do not include audience as a component.Therefore,the purpose of this paper is to introduce an alternative revision model for novice writers at or higher than highschool level with a focus on audience and feedback.First,the definition of revision is made,which is followed by summaries of the importance of audience and feedback in writing.Second,available revision models in literature that serves as the basis of the alternative model are reviewed.Finally,the alternative revision model is introduced with its components and the way these components work is explained.The revision model presented in this paper will contribute to literature on writing by filling the gap in revision models by proposing a model for novice writers and highlighting the importance of audience and feedback.展开更多
Over the past six decades,the implementation of soil and water conservation measures has significantly reduced soil erosion and sediment yield on the Loess Plateau,China.However,while the overall reduction is well-doc...Over the past six decades,the implementation of soil and water conservation measures has significantly reduced soil erosion and sediment yield on the Loess Plateau,China.However,while the overall reduction is well-documented,the dynamic interplay between soil erosion potential and sediment connectivity,specifically how they spatially covary under land use/cover changes,remains insufficiently understood.To address this gap,this study established a model framework by integrating the revised universal soil loss equation(RUSLE),index of connectivity(IC),and sediment delivery ratio(SDR)to evaluate the spatio-temporal variations in soil erosion and sediment yield in the Hantaichuan Watershed,northern Loess Plateau,China,from 1995 to 2020 and to estimate the effects of land use/cover changes and check dam construction on sediment yield.The results revealed that the soil erosion in the Hantaichuan Watershed decreased by 43.90% from 1995 to 2020 and the sediment yield decreased by 69.28% under the combination of land use/cover changes and check dam construction.The IC and soil erosion(IC-SE)map revealed both the coupling and decoupling covariation relationships between sediment connectivity and soil erosion.By 2020,areas with high connectivity and high erosion(I-E)covered only 18.67% of the watershed,while contributed more than 40.00% to the total erosion.The I-E zones were mainly located in the central part of the watershed where aeolian sands derived from the Hobq Desert are concentrated and were identified as critical areas for soil and water conservation.This study provides support for priority management of watershed conservation measures as well as a valuable reference for future studies.展开更多
基金Under the auspices of Major State Basic Research Development Program of China (973 Program) (No. 2004CB418502,No. 2007CB407205)the Knowledge Innovation Programs of Chinese Academy of Sciences (No. KSCX1-YW-09-13)
文摘Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin.It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source.In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps(S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin.Chemical oxygen demand(COD) and ammonia nitrogen(NH 3-N) loads were estimated.Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively.NH 3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively.Point source pollution was stronger than nonpoint source pollution in the study area at present.The water quality of upstream was better than that of downstream of the rivers and cities.It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin.The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating.
基金supported by the National Key Research and Development Program of China(2016YFC0501603)the National Natural Science Foundation of China(Nos.41671025+2 种基金413904614123085241471029)
文摘Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological impact evaluation. In this study, throughfall, stemflow and interception were measured in a pure Larix principis-rupprechtii Mayr.（larch） plantation in the Liupan Mountains of northwestern China during the growing season（May–October） of 2015, and simulated using a revised Gash model. During the study period, the total precipitation was 499.0 mm; corresponding total throughfall, stemflow and canopy interception were 410.3, 2.0 and 86.7 mm,accounting for 82.2, 0.4 and 17.4% of the total precipitation, respectively. With increasing rainfall, the canopy interception ratio of individual rainfall events decreased initially and then tended to stabilize. Within the study period, the simulated total canopy interception, throughfall and stemflow were 2.2 mm lower, 2.5 mm higher and 0.3 mm lower than their measured values, with a relative error of 2.5, 0.6 and 15.0%, respectively. As quantified by the model, canopy interception loss（79%） mainly consisted of interception caused by canopy adsorption, while the proportions of additional interception and trunk interception were small. The revised Gash model was highly sensitive to the parameter of canopy storage capacity,followed by the parameters of canopy density and mean rainfall intensity, but less sensitive to the parameters of mean evaporation rate, trunk storage capacity, and stemflow ratio. The revised Gash model satisfactorily simulated the total canopy interception of the larch plantation within the growing season but was less accurate for some individual rainfall events, indicating that some flaws exist in the model structure. Further measures to improve the model’s ability in simulating the interception of individual rainfall events were suggested.
基金Under the auspices of Water Pollution Control and Management Key Project of Science and Technology of China(No.2013ZX07202-007)Liaoning Hundred-Thousand-Ten Thousand Talents Program
文摘Rivers in the Liaohe River Estuary area have been seriously polluted by discharges of wastewater containing petroleum pol- lutants and nutrients. In this paper, The Enhanced Stream Water Quality Model （QUAL2K） and its revised model as well as One-dimensional Tide Mean Model （1D model） were applied to predict and assess the water quality of the tidal fiver reach of the Liaohe River Estuary. Dissolved oxygen （DO）, biochemical oxygen demand （BODs）, ammonia nitrogen （NH3-N） and total phosphorus （TP） were chosen as water quality indices in the two model simulations. The modelled results show that the major reasons for degraded rivers remain petroleum and non-point source pollution. Tidal water also has a critical effect on the variation of water quality. The sensitivity analysis identifies that flow rate, point load and diffuse load are the most sensitive parameters for the four water quality indices in the revised QUAL2K simulation. Uncertainty analysis based on a Monte Carlo simulation gives the probability distribution of the four wa- ter quality indices at two locations （6.50 km and 44.84 km from the river mouth）. The statistical outcomes indicate that the observed data fall within the 90% confidence intervals at all sites measured, and show that the revised QUAL2K gives better results in simulating the water quality of a tidal fiver.
文摘The research is motivated by the ongoing the electromagnetic continuous casting of molten metal. The revised k-ε model considering the effect of magnetic field application was derived. The specific model equations for the electromagnetic braking were used to calculate the velocity distribution in the continuous casting mold of steel. The results show that the revised k-ε model considering the effect of magnetic field application tends to suppress the production of turbulence and difference between the conventional and revised k-e model is small.
文摘Quasi-elastic neutron scattering(QENS) has many applications that are directly related to the development of highperformance functional materials and biological macromolecules, especially those containing some water. The analysis method of QENS spectra data is important to obtain parameters that can explain the structure of materials and the dynamics of water. In this paper, we present a revised jump-diffusion and rotation-diffusion model(rJRM) used for QENS spectra data analysis. By the rJRM, the QENS spectra from a pure magnesium-silicate-hydrate(MSH) sample are fitted well for the Q range from 0.3 ^(-1) to 1.9 ^(-1) and temperatures from 210 K up to 280 K. The fitted parameters can be divided into two kinds. The first kind describes the structure of the MSH sample, including the ratio of immobile water(or bound water) C and the confining radius of mobile water a_0. The second kind describes the dynamics of confined water in pores contained in the MSH sample, including the translational diffusion coefficient Dt, the average translational residence timeτ0, the rotational diffusion coefficient D_r, and the mean squared displacement(MSD) u^2. The r JRM is a new practical method suitable to fit QENS spectra from porous materials, where hydrogen atoms appear in both solid and liquid phases.
基金The National Natural Science Foundation of China(No.51575304)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2012ZX04012011)
文摘In order to investigate the sand mold strength after the aeration sand filling-high pressure squeeze moldingprocess,a tree-dimentional(3D)numerical simulation was introduced.The commercial finite element method(FEM)software ABAQUScombined with a revised Drucker-Prager/Cap model was used to simulate the squeeze compaction process.Additionally,the sand bulk density after the aeration sand filling process was tested by a specially designed experiment,which divided the whole sand bulk in the molding chamber into5x9regions and it was used as the input to simulate the squeeze process.During the simulation process,the uniform modeling simulation and the patition modeling simulation methods were used a d the3D numercal simulation results were compared with correlative benchmark testings.From the3D numerica simulation results,it can be concluded that the uniform sand bulk density distribution can obtain a high quality sandmold and the revised Drncker-Pager/Cap model is suitable for handling the situation with the complex paaern.The3D numerical simulation results can predict well the sand mold strength distribution and can be used as guidelines for the production practice.
文摘Revision is a complex,yet important phase in writing to improve the quality of a text.Some revision models are created to explain its components and the ways these components work.However,analysis of available models shows that they are proposed mainly for expert writers,who can complete the complex revision process individually,without the need of support or feedback.Most of the available revision models also do not include audience as a component.Therefore,the purpose of this paper is to introduce an alternative revision model for novice writers at or higher than highschool level with a focus on audience and feedback.First,the definition of revision is made,which is followed by summaries of the importance of audience and feedback in writing.Second,available revision models in literature that serves as the basis of the alternative model are reviewed.Finally,the alternative revision model is introduced with its components and the way these components work is explained.The revision model presented in this paper will contribute to literature on writing by filling the gap in revision models by proposing a model for novice writers and highlighting the importance of audience and feedback.
基金supported by the National Natural Science Foundation of China(42077076,42177323)the National Natural Science Foundation of China and Yellow River Water Science Research Joint Fund(U2243211).
文摘Over the past six decades,the implementation of soil and water conservation measures has significantly reduced soil erosion and sediment yield on the Loess Plateau,China.However,while the overall reduction is well-documented,the dynamic interplay between soil erosion potential and sediment connectivity,specifically how they spatially covary under land use/cover changes,remains insufficiently understood.To address this gap,this study established a model framework by integrating the revised universal soil loss equation(RUSLE),index of connectivity(IC),and sediment delivery ratio(SDR)to evaluate the spatio-temporal variations in soil erosion and sediment yield in the Hantaichuan Watershed,northern Loess Plateau,China,from 1995 to 2020 and to estimate the effects of land use/cover changes and check dam construction on sediment yield.The results revealed that the soil erosion in the Hantaichuan Watershed decreased by 43.90% from 1995 to 2020 and the sediment yield decreased by 69.28% under the combination of land use/cover changes and check dam construction.The IC and soil erosion(IC-SE)map revealed both the coupling and decoupling covariation relationships between sediment connectivity and soil erosion.By 2020,areas with high connectivity and high erosion(I-E)covered only 18.67% of the watershed,while contributed more than 40.00% to the total erosion.The I-E zones were mainly located in the central part of the watershed where aeolian sands derived from the Hobq Desert are concentrated and were identified as critical areas for soil and water conservation.This study provides support for priority management of watershed conservation measures as well as a valuable reference for future studies.
