Estimation of groundwater residence time and recession rate in watershed of the Loess Plateau     

ZHU Ruirui  ZHENG Hongxing  LIU Changming 《地理学报》2010,20(2):273-282

Groundwater residence time is an important indicator of hydrological cycle and essential for water resources development and utilization. In this paper, groundwater residence time in non-flood season, flood season and water year has been determined from daily streamflow hydrograph of ten hydrological stations in Wudinghe River Basin located in the middle reaches of the Yellow River Basin. Results have showed that: baseflow recession constant in Wudinghe River Basin ranges from 0.72 to 0.94 with a larger recession rate in flood season than that in non-flood season. Spatially, the recession rate of baseflow in loess area is the biggest, but is the smallest in the sandy area. The half-residence time of groundwater varies from 1.8 to 45.5 days while overall residence time of groundwater is between 34 and 342 days in different sub-basins of the Wudinghe River Basin. The annual average overall residence time of groundwater decreases from 117 days in the upper reaches to 73 days in the lower reaches.  相似文献   

Metal Ion Extraction with Bipyridine Derivatives as Chelating Ligands in Supercritical Carbon Dioxide     

Hai‐Jian Yang  Hakwon Kim  Cun‐Yue Guo 《洁净——土壤、空气、水》2010,38(2):159-166

Three fluorinated bipyridine ligands have been designed and synthesized as chelating agents for the extraction of metal ions in supercritical CO₂ (sc‐CO₂). The ligand solubilities in sc‐CO₂ were investigated at different temperatures and pressures, and the measured data have been correlated using a semiempirical model. The calculated results showed satisfactory agreement with the experimental data. Based on these data, metal ion extraction with the three compounds as chelating agents in sc‐CO₂ was performed from spiked filter paper, whereby ligand 1 showed the highest extraction efficiency, especially for Ni²⁺ and Cu²⁺. The extraction constants, K_ex, of the three chelating ligands were seen to increase with increasing extraction efficiency for the same metal ion in the same extraction system.  相似文献   

陀螺经纬仪的仪器常数随温度漂移规律的研究     

王飞  邓向瑞  李广云  范百兴 《武汉大学学报(信息科学版)》2011,(3):289-292

对某型陀螺经纬仪的仪器常数受环境温度的影响进行实验,利用数理统计方法分析、处理了各温度下仪器常数的数据,发现其变化符合线性规律,从而可实现温度对仪器常数的漂移影响的自动补偿。  相似文献   

Pipe Service Age Effect on Chlorine Decay in Drinking‐Water Transmission and Distribution Systems     

A. O. Al‐Jasser 《洁净——土壤、空气、水》2011,39(9):827-832

Maintaining acceptable quality of water transported in the transmission and distribution system requires the chlorination of water beyond the treatment plant. While flowing through pipes, the chlorine concentration decreases for different reasons. Reaction with the pipe material itself and the reaction with both the biofilm and tubercles formed on the pipe wall are known as pipe wall demand. This varies with pipe parameters. The aim of this paper was to assess the impact of the service age of pipes on the chlorine wall decay constant. One hundred and fifty three pipe sections of different sizes and four different pipe materials were collected and tested for their chlorine first‐order wall decay constants. The results showed that pipe service age was an important factor that must not be ignored. For the range of the 55 years of pipe service age used in this study, the change in the wall decay ranged from 8 to 531% of the corresponding values in the recently installed pipes. The effect of service age on the wall decay constants was most evident in steel pipes. Other important findings were reached.  相似文献   

Effect of hysteretic smoothness on inelastic response spectra with constant‐ductility     

Jong‐Keol Song  Henri P. Gavin 《地震工程与结构动力学》2011,40(7):771-788

This paper presents an efficient methodology for computing constant‐ductility inelastic response spectra. The computation of constant‐ductility spectra involves numerical root‐finding algorithms to find the strongest structure providing a desired ductility response. Smooth inelastic structural behavior is modeled using a first‐order nonlinear differential equation and the transient structural response is solved using an implicit algorithm requiring Newton iterations at each time step. For structural models with smooth hysteretic behavior (not piece‐wise linear), a simple root‐finding method involving a combination of hyperbolic fits, linear interpolation, and Newton's method converges upon the highest strength (conservative) solution with a small number of iterations. The effect of the hysteretic smoothness on the occurrence of multiple roots is examined for two near‐fault and two far‐fault earthquake records, and for two measures of ductility and for normalized hysteretic energy. The results indicate how the smoothness of the hysteretic behavior affects ductility demand and constant‐ductility response spectra. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

基于异常线圈的时间域AEM系统测试和标定方法研究   总被引：3，自引：2，他引：1       下载免费PDF全文

嵇艳鞠  李肃义  于生宝  朱凯光  周逢道  王言章  王世隆  刘焕江  任广群  林君 《地球物理学报》2011,54(10):2690-2697

为了检验和测试时间域航空电磁系统的测量精度和有效性,采用地面铺设闭合的异常线圈模拟地下有限导体的方法,将异常线圈的电磁响应理论值与系统实测数据进行拟合分析,来确定系统误差和飞行几何参数误差.在计算异常线圈电磁响应的基础上,研究了衰减曲线、剖面曲线与线圈的电性、几何参数关系,设计了野外测试实验方案.在长春市大鹅岛附近,采用吊车进行了系统测试,测试结果表明:单点实测数据的平均绝对误差为0.48 mV,系统相对误差小于1%,飞行高度误差为0.4 m、水平偏移误差为0.2 m.基于异常线圈进行时间域航空电磁系统的测试和标定,是一种准确、快速、经济可行的方法,具有野外施工便捷、参数调整灵活等特点,适用于任何时间域电磁测量系统的检测.  相似文献   

Prediction of buried calcite dissolution in the Ordovician carbonate reservoir of the Tahe Oilfield,NW china: Evidence from formation water     

Zhuang Ruan  Bingsong Yu  Lidong Wang  Yinglu Pan  Guanghui Tan 《Chemie der Erde / Geochemistry》2013

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交叉偶极子声测井多频率反演地层三阶弹性常数和地应力研究   总被引：1，自引：0，他引：1       下载免费PDF全文

陈浩  王秀明  赵立新 《地球物理学报》2009,52(6):1663-1674

基于声弹性理论,本文详细论述了利用交叉偶极子多频率相速度反演地层三阶弹性常数和地应力的理论及信噪比对反演结果的影响.定性和定量分析表明在速度应力方程中,不含三阶弹性常数项与含三阶弹性常数项相比对速度的影响可以忽略,由此只利用一次测井资料同时反演地应力和三阶弹性常数是一个严重病态的问题或一个不确定性问题.针对不同的反演模型,详细考察了信噪比对各自简化模型和精确模型反演结果的影响.数值模拟结果表明,利用一次测井采用精确模型反演全部四个参数方法受信噪比影响严重.而利用不同流体压力下的测井资料进行反演时可以采用简化模型取代精确模型以便简化计算和提高反演速度,因为简化模型和精确模型有着几乎相同的精度;同时,分步反演的方法可以较好地反演出原位地应力及三阶弹性常数.  相似文献   

结构动力方程的显式级数积分格式     

郭泽英  李青宁 《地震工程与工程振动》2009,29(4)

将Newmark-β法中常平均加速度法的基本假定与精细指数算法结合,根据指数矩阵的Taylor级数展开式,提出了动力方程的显式级数解,并设计了相应的时程积分算法.该算法的精度可根据Taylor级数展开式的项数进行灵活控制.算例的结果表明:在满足稳定性条件的前提下,随着时间步长的增加,其精度优于传统的时程积分法.通过稳定性的分析,指出其稳定性条件是显然满足的.  相似文献   

高精度恒误差数字频率计设计   总被引：2，自引：0，他引：2  

周欣 《南京气象学院学报》2000,23(3):435-439

基于高精度恒误差测频原理,采用Ｌａｔｔｉｃｅ的在系统可编程器件（ｉｓｐＬＳＩ）进行数字频率计设计。结果表明,高精度恒误差测频原理是合理的,并对所采用的高精度恒误差测频原理作了深入的理论分析,给出了依据此原理实现的硬件电路。  相似文献