A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration (ET0) to perturbation of four climate variables in Tao'er River Basin of the northeaste...A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration (ET0) to perturbation of four climate variables in Tao'er River Basin of the northeastern China. Mean monthly ET0 and yearly ET0 from 1961 to 2005 were estimated with the FAO-56 Penman-Monteith Equation. A 45-year historical dataset of average monthly maximum/minimum air temperature, mean air temperature, wind speed, sunshine hours and relative humidity from 15 meteorological stations was used in the analysis. Results show that: 1) Sensitivity coefficients of wind speed, air temperature and sunshine hours were positive except for those of air tem- perature of Arxan Meteorological Station, while those of relative humidity were all negative. Relative humidity was the most sensitive variable in general for the Tao'er River Basin, followed by sunshine hours, wind speed and air tem- perature. 2) Similar to climate variable, monthly sensitivity coefficients exhibit large annual fluctuations. 3) Sensitivity coefficients for four climate variables all showed significant trends in seasonal/yearly series. Also, sensitivity coefficients of air temperature, sunshine hours and wind speed all showed significant trends in spring. 4) Among all sensitiv- ity coefficients, the average yearly sensitivity coefficient of relative humidity was highest throughout the basin and showed largest spatial variability. Longitudinal distribution of sensitivity coefficients for air temperature, relative hu- midity and sunshine hours was also found, which was similar to the distribution of the three climate variables.展开更多
由于螺纹复杂的几何结构,在对螺纹部件进行有限元分析时,螺纹部件的内外螺纹面往往难以啮合,常造成螺纹结构有限元建模困难、模型数值计算收敛性差等问题。本文基于垂直于螺纹轴线的任意横截面几何形状相同的事实,选取国际标准化组织(In...由于螺纹复杂的几何结构,在对螺纹部件进行有限元分析时,螺纹部件的内外螺纹面往往难以啮合,常造成螺纹结构有限元建模困难、模型数值计算收敛性差等问题。本文基于垂直于螺纹轴线的任意横截面几何形状相同的事实,选取国际标准化组织(International Organization for Standardization,ISO)制定的标准螺旋线公式,采用3维8节点单元,精确建立了螺纹连接件有限元模型。该模型不仅考虑了螺纹螺旋升角对模型的影响,且模型中组成每个节距的单元层排列整齐,每层单元上的节点编号分布有序,内外螺纹面上的节点相互贴近。这些特质使得模型能够准确映射工程中螺纹连接结构的力学特性,优化模型数值计算收敛性,便于对模型数值计算结果开展力学剖面分析。为验证本文螺纹连接结构有限元建模方案的有效性,首先,在理论分析方面对螺纹连接结构中拧紧转角与轴向力的关系和螺纹连接结构中轴向力的分布进行了计算推导,并以M12标准螺栓为例,计算其轴向力分布。然后,通过数值模拟的方法先后验证了该螺纹连接结构拧紧转角和轴向力关系与理论分析结果的一致性、M12螺栓的轴向力分布与理论计算结果的一致性、螺纹齿根处应力集中系数状态与实验结果的一致性,以及应力分布和塑性应变分布与实际工程测量的一致性。基于螺纹连接结构有限元模型生成的方案开发了一款螺栓螺母有限元参数化建模软件,软件可根据输入的螺纹直径、节距数量等参数快捷地查看和生成不同型号的螺栓螺母3维有限元模型;在工程分析和优化设计中,使用该软件既避免了设计人员繁琐的重复劳动,又提高了设计精度和工作效率,能更好地满足实际工程需要。展开更多
The Taoer River basin is the epitome in the west of Northeast China and it is one of the most fragile and sensitive ecoregions. Thus, protection of water quality of the Taoer River is important. Not only point source ...The Taoer River basin is the epitome in the west of Northeast China and it is one of the most fragile and sensitive ecoregions. Thus, protection of water quality of the Taoer River is important. Not only point source pollution but non-point source (NPS) pollution results in deteriorating water quality. In this study, long-term hydrologic impact assessment model was used to evaluate the impacts of land use change impacts on NPS pollution, and the replacement cost method was used to calculate the economic loss caused by NPS pollution. Through analyzing the NPS pollutant loads of different land categories and the economic loss, the article puts forward that there exists a close relationship between land-use types and NPS pollution, and agricultural pollution is the main component of the NPS pollution in this area. The results of this study can provide decision-making basis for agricultural development and land-use change.展开更多
基金Under the auspices of National Natural Science Foundation of China (No. 40571029)
文摘A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration (ET0) to perturbation of four climate variables in Tao'er River Basin of the northeastern China. Mean monthly ET0 and yearly ET0 from 1961 to 2005 were estimated with the FAO-56 Penman-Monteith Equation. A 45-year historical dataset of average monthly maximum/minimum air temperature, mean air temperature, wind speed, sunshine hours and relative humidity from 15 meteorological stations was used in the analysis. Results show that: 1) Sensitivity coefficients of wind speed, air temperature and sunshine hours were positive except for those of air tem- perature of Arxan Meteorological Station, while those of relative humidity were all negative. Relative humidity was the most sensitive variable in general for the Tao'er River Basin, followed by sunshine hours, wind speed and air tem- perature. 2) Similar to climate variable, monthly sensitivity coefficients exhibit large annual fluctuations. 3) Sensitivity coefficients for four climate variables all showed significant trends in seasonal/yearly series. Also, sensitivity coefficients of air temperature, sunshine hours and wind speed all showed significant trends in spring. 4) Among all sensitiv- ity coefficients, the average yearly sensitivity coefficient of relative humidity was highest throughout the basin and showed largest spatial variability. Longitudinal distribution of sensitivity coefficients for air temperature, relative hu- midity and sunshine hours was also found, which was similar to the distribution of the three climate variables.
文摘由于螺纹复杂的几何结构,在对螺纹部件进行有限元分析时,螺纹部件的内外螺纹面往往难以啮合,常造成螺纹结构有限元建模困难、模型数值计算收敛性差等问题。本文基于垂直于螺纹轴线的任意横截面几何形状相同的事实,选取国际标准化组织(International Organization for Standardization,ISO)制定的标准螺旋线公式,采用3维8节点单元,精确建立了螺纹连接件有限元模型。该模型不仅考虑了螺纹螺旋升角对模型的影响,且模型中组成每个节距的单元层排列整齐,每层单元上的节点编号分布有序,内外螺纹面上的节点相互贴近。这些特质使得模型能够准确映射工程中螺纹连接结构的力学特性,优化模型数值计算收敛性,便于对模型数值计算结果开展力学剖面分析。为验证本文螺纹连接结构有限元建模方案的有效性,首先,在理论分析方面对螺纹连接结构中拧紧转角与轴向力的关系和螺纹连接结构中轴向力的分布进行了计算推导,并以M12标准螺栓为例,计算其轴向力分布。然后,通过数值模拟的方法先后验证了该螺纹连接结构拧紧转角和轴向力关系与理论分析结果的一致性、M12螺栓的轴向力分布与理论计算结果的一致性、螺纹齿根处应力集中系数状态与实验结果的一致性,以及应力分布和塑性应变分布与实际工程测量的一致性。基于螺纹连接结构有限元模型生成的方案开发了一款螺栓螺母有限元参数化建模软件,软件可根据输入的螺纹直径、节距数量等参数快捷地查看和生成不同型号的螺栓螺母3维有限元模型;在工程分析和优化设计中,使用该软件既避免了设计人员繁琐的重复劳动,又提高了设计精度和工作效率,能更好地满足实际工程需要。
基金supported by the Key Project of Knowledge Innovation Program of CAS(Grant No.KZCX2-YW-Q06-1)
文摘The Taoer River basin is the epitome in the west of Northeast China and it is one of the most fragile and sensitive ecoregions. Thus, protection of water quality of the Taoer River is important. Not only point source pollution but non-point source (NPS) pollution results in deteriorating water quality. In this study, long-term hydrologic impact assessment model was used to evaluate the impacts of land use change impacts on NPS pollution, and the replacement cost method was used to calculate the economic loss caused by NPS pollution. Through analyzing the NPS pollutant loads of different land categories and the economic loss, the article puts forward that there exists a close relationship between land-use types and NPS pollution, and agricultural pollution is the main component of the NPS pollution in this area. The results of this study can provide decision-making basis for agricultural development and land-use change.
