The loess plateau in northwestern China with an area of 640 000km^2, which has developed the loess deposits with a thickness up to 200m in typical areas, is regarded as a huge carbon stock like the karst area in south...The loess plateau in northwestern China with an area of 640 000km^2, which has developed the loess deposits with a thickness up to 200m in typical areas, is regarded as a huge carbon stock like the karst area in southwestern China, and plays an important role in regional(even global) carbon cycle. But the spring discharging from loess is poorly known compared with karst spring so far. The objective of this study is to ascertain the characteristics and origin of spring at Qiushe Village, Lingtai County, Gansu Province by hydro-chemical and isotopic methods. The results show that the springs including LGQ, HMQ, YYQ and CZQ are the depression spring and belong to the same shallow aquifer with the well water JZJ. There are not distinct seasonal/diurnal-scale variations on the hydro-chemical characteristics of the spring water(LGQ, HMQ, YYQ, CZQ) and groundwater(JZJ). The hydro-chemical type of groundwater is Ca·Mg-HCO_3. The D and O isotope ratios indicate that the precipitation is the main recharge source of groundwater in study area. And the results of tritium(TU) and Cl concentration suggest that the recharge cycle of groundwater may be more than 60 yrs. Our study shows that the water cycle in loess plateau including rainfall, infiltration, recharge and discharge exerts a continuous impact on carbon stock in loess, which should be paid more attention to in future research on the quantitative reconstruction of paleoclimate.展开更多
3D IC integration allows multiple two-dimensional circuits to be stacked vertically as single die,improved integration density,noise immunity,and superior performance resulting in high reliability performance[1-3].
瑞利阻尼模型广泛应用于结构的多维抗震计算中,阻尼系数计算方法影响地震响应。因此,有必要对多维地震作用下结构的瑞利阻尼系数实用计算方法进行研究。首先,基于单维地震激励应变能时程响应,求得任意阶振型对应应变能响应的最大值,并...瑞利阻尼模型广泛应用于结构的多维抗震计算中,阻尼系数计算方法影响地震响应。因此,有必要对多维地震作用下结构的瑞利阻尼系数实用计算方法进行研究。首先,基于单维地震激励应变能时程响应,求得任意阶振型对应应变能响应的最大值,并结合完全平方和平方根(Complete Quadratic Combination,CQC)振型组合方式,得到单维地震激励应变能响应计算方法。在此基础上,利用平方和平方根(Square Root of Sum of Square,SRSS)多维组合方法和等价处理,构建振型阻尼比变化量平方的新型权重因子,并提出了瑞利阻尼系数实用计算方法。分别以带楼板的塔式结构和不带楼板的K8单层球面网壳结构为例,对瑞利阻尼系数实用计算方法和已有基于应变能响应阻尼系数算法进行了比较。结果表明:应用瑞利阻尼系数实用计算方法求得的各类结构的节点位移和杆件内力误差均较小,且计算效率更高;所提出的瑞利阻尼系数实用计算方法是合理的,可应用于结构多维抗震计算。展开更多
基金supported by the Chinese National Natural Science Foundation (No.414 03107 and No.41325010)the Basic Science Research Fund from the Institute of Hydrogeology and Environmental Geology (No. SK201208)China Geological Survey Projects (No. 1212011 3005900)
文摘The loess plateau in northwestern China with an area of 640 000km^2, which has developed the loess deposits with a thickness up to 200m in typical areas, is regarded as a huge carbon stock like the karst area in southwestern China, and plays an important role in regional(even global) carbon cycle. But the spring discharging from loess is poorly known compared with karst spring so far. The objective of this study is to ascertain the characteristics and origin of spring at Qiushe Village, Lingtai County, Gansu Province by hydro-chemical and isotopic methods. The results show that the springs including LGQ, HMQ, YYQ and CZQ are the depression spring and belong to the same shallow aquifer with the well water JZJ. There are not distinct seasonal/diurnal-scale variations on the hydro-chemical characteristics of the spring water(LGQ, HMQ, YYQ, CZQ) and groundwater(JZJ). The hydro-chemical type of groundwater is Ca·Mg-HCO_3. The D and O isotope ratios indicate that the precipitation is the main recharge source of groundwater in study area. And the results of tritium(TU) and Cl concentration suggest that the recharge cycle of groundwater may be more than 60 yrs. Our study shows that the water cycle in loess plateau including rainfall, infiltration, recharge and discharge exerts a continuous impact on carbon stock in loess, which should be paid more attention to in future research on the quantitative reconstruction of paleoclimate.
文摘3D IC integration allows multiple two-dimensional circuits to be stacked vertically as single die,improved integration density,noise immunity,and superior performance resulting in high reliability performance[1-3].
文摘瑞利阻尼模型广泛应用于结构的多维抗震计算中,阻尼系数计算方法影响地震响应。因此,有必要对多维地震作用下结构的瑞利阻尼系数实用计算方法进行研究。首先,基于单维地震激励应变能时程响应,求得任意阶振型对应应变能响应的最大值,并结合完全平方和平方根(Complete Quadratic Combination,CQC)振型组合方式,得到单维地震激励应变能响应计算方法。在此基础上,利用平方和平方根(Square Root of Sum of Square,SRSS)多维组合方法和等价处理,构建振型阻尼比变化量平方的新型权重因子,并提出了瑞利阻尼系数实用计算方法。分别以带楼板的塔式结构和不带楼板的K8单层球面网壳结构为例,对瑞利阻尼系数实用计算方法和已有基于应变能响应阻尼系数算法进行了比较。结果表明:应用瑞利阻尼系数实用计算方法求得的各类结构的节点位移和杆件内力误差均较小,且计算效率更高;所提出的瑞利阻尼系数实用计算方法是合理的,可应用于结构多维抗震计算。
