二维渗流有限元法在潮州水库浸没分析中的应用   总被引：1，自引：0，他引：1  

朱杰  王汇明 《四川地质学报》2006,26(2):121-124

通过对潮州市意东堤、北堤及东厢堤段的二维渗流计算,了解在潮州供水枢纽建成前后的潮州市城区地下水位变化情况,从而判断在枢纽建成后,在长期处于正常蓄水位的情况下,潮州市城区的浸没情况。同时复核在采取工程措施的情况下,对堤后浸没区的影响,确保在枢纽建成后,潮州市不产生浸没。  相似文献   

矿物聚合材料基体相的形成过程研究   总被引：6，自引：0，他引：6       下载免费PDF全文

王刚  马鸿文 《岩石矿物学杂志》2005,24(2):133-138

基体相在矿物聚合材料结构中起与其他矿物表面键合的作用 ,是材料强度的来源。本实验以富钾岩石提钾后的硅铝质溶胶相加NaOH固体 ,在 6 0℃下制备矿物聚合材料基体相 ,并采用XRD、SEM、IR、NMR等分析手段研究了不同固化时间基体相的结构。研究结果表明 ,在基体相的形成过程中 ,没有新的结晶相产生 ,说明基体相为一种半晶质到非晶质物相 ;随着固化时间的变化 ,其自身 [SiO4]4-四面体发生解聚又重新聚合 ,聚合后基体相形成了致密完整的块体  相似文献   

Presidential Address 2003: Why concrete cracks — geological factors in concrete failure     

William J. French 《Proceedings of the Geologists' Association. Geologists' Association》2005,116(2):89-105

  相似文献   

2D Monte Carlo versus 2D Fuzzy Monte Carlo health risk assessment   总被引：15，自引：4，他引：11  

E. Kentel  M. M. Aral 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(1):86-96

Risk estimates can be calculated using crisp estimates of the exposure variables (i.e., contaminant concentration, contact rate, exposure frequency and duration, body weight, and averaging time). However, aggregate and cumulative exposure studies require a better understanding of exposure variables and uncertainty and variability associated with them. Probabilistic risk assessment (PRA) studies use probability distributions for one or more variables of the risk equation in order to quantitatively characterize variability and uncertainty. Two-dimensional Monte Carlo Analysis (2D MCA) is one of the advanced modeling approaches that may be used to conduct PRA studies. In this analysis the variables of the risk equation along with the parameters of these variables (for example mean and standard deviation for a normal distribution) are described in terms of probability density functions (PDFs). A variable described in this way is called a second order random variable. Significant data or considerable insight to uncertainty associated with these variables is necessary to develop the appropriate PDFs for these random parameters. Typically, available data and accuracy and reliability of such data are not sufficient for conducting a reliable 2D MCA. Thus, other theories and computational methods that propagate uncertainty and variability in exposure and health risk assessment are needed. One such theory is possibility analysis based on fuzzy set theory, which allows the utilization of incomplete information (incomplete information includes vague and imprecise information that is not sufficient to generate probability distributions for the parameters of the random variables of the risk equation) together with expert judgment. In this paper, as an alternative to 2D MCA, we are proposing a 2D Fuzzy Monte Carlo Analysis (2D FMCA) to overcome this difficulty. In this approach, instead of describing the parameters of PDFs used in defining the variables of the risk equation as random variables, we describe them as fuzzy numbers. This approach introduces new concepts and risk characterization methods. In this paper we provide a comparison of these two approaches relative to their computational requirements, data requirements and availability. For a hypothetical case, we also provide a comperative interpretation of the results generated.  相似文献   

利用走时反演二维多孔介质渗透率   总被引：2，自引：1，他引：2       下载免费PDF全文

李树勇  张关泉  LIU Jun 《地球物理学报》2002,45(6):870-879

综合利用直接方法和优化方法研究二维多孔介质渗透率反演问题. 问题的提法与前人不同,是由区域内各点流体渗透的走时来反演渗透率. 该反问题的求解可分成两步进行,归结为两个相应的子问题进行研究. 首先由流体走时反演二维多孔介质速度场的数值算法,然后由二维多孔介质速度场反演二维多孔介质渗透率的数值算法,最后给出数值例子. 数值结果表明了所用数值方法的正确性和有效性.  相似文献   

油田污水中Fe2+,S2-,DO及pH值对无机交联体系HPAM-Cr3+CDG成胶性能影响的研究   总被引：1，自引：2，他引：1  

陈艳玲  范畴  杨问华  谭中良  费琪 《地质科技情报》2002,21(2):83-86

在对河南油田下二门矿区油田污水进行全面分析的基础上，研究了污水中Fe^2 ，S^2-，溶解氧（DO）及污水的pH值对无机交联体系聚丙烯酰胺（HPAM）－Cr^3 胶成分散凝胶（CDG）成胶性能的影响。研究结果表明，对于HPAM－Cr^3 体系，污水中Fe^2 ，DO对其成胶性能没有影响；S^2-和污水的pH值对其成胶性能有影响。pH值增大，凝胶强度增强；S^2-浓度增加，则凝胶强度减弱。  相似文献   

夏季北极海冰激发的500hPa遥相关型   总被引：11，自引：0，他引：11  

方之芳  谭友邦  隋学海 《大气科学》1991,15(1):53-60

本文应用统计方法,分析7月、8月北极海冰与北半球500hPa位势高度场的相关场,7月、8月500hPa基点相关图,多冰年与少冰年的1000—500hPa厚度差图等,得到如下结论: 夏季极冰冷源的存在,可激发北半球大气产生遥相关型,这种遥相关型可以看成二维Rossby波列,具有相当正压结构,在西风带中沿着固定的波导自高纬向低纬分布,从而影响北美的环流和天气。表现为极冰偏多年份,极涡加强而偏心,加拿大高压脊和北美大槽亦同时加强;反之,极冰偏少年份,上述系统均减弱。  相似文献   

山谷风环流控制下的大气污染物输送和扩散过程:二维数值模拟研究   总被引：3，自引：0，他引：3  

邱崇践  蒲朝霞 《高原气象》1991,(4)

本文以兰州地区的实际地形为背景,建立了一个二维小尺度数值模式,并用它对山谷之间热力差异造成的山谷风环流及其控制下山谷中高架源排放的污染物输送和扩散过程进行了模拟研究。结果表明,在山谷风环流控制下,造成山谷内高污染浓度的主要因素有两个:一是日出前和日落后山谷风的转换;二是在白天由于山谷风环流所造成的山谷上空较强的下沉气流。  相似文献   

Use of ultrasonic treatment for extraction of humic acid with inorganic reagents from soil     

A.U. Ramunni  F. Palmieri 《Organic Geochemistry》1985,8(4):241-246

The use of ultrasonic vibrations (1 hr) on the extraction of humic acids (HA) from a brown soil has been compared with the extraction by mechanical stirring (24 hr) with two extractants: 0.5 N and 0.1 M Na₄P₂O₇, followed by extraction with 0.5 N NaOH. In the pyrophosphate extraction, ultrasonic and mechanical treatments produced the same yield of HA. Further extraction with NaOH and mechanical stirring gave higher yields.The elemental composition of HA changed remarkably with both ultrasonic and mechanical systems. The HA extracted with ultrasonic treatment showed a higher ash content and a lower content of COOH and phenolic OH groups. These HA's showed higher optical density at 260 and 450 nm when pyrophosphate-extracted, and lower optical density when NaOH-extracted. Moreover the ultrasonic-treated HA in both extractants showed a lower E₄₀₀/E₆₀₀ ratio.Infrared examination confirmed the difference in chemical characteristics of extracted HA. The HA distribution in the different classes of nominal molecular weights by Sephadex gel filtration was influenced by both ultrasonic and mechanical systems, specially for molecular weights between 5000 and 150,000. It has been noted that the differences due to both systems are less marked than those caused by ssing different extractants.  相似文献   

二维地震资料波动方程非线性反演   总被引：3，自引：3，他引：3       下载免费PDF全文

陈小宏  牟永光 《地球物理学报》1996,39(3):401-408

针对反演的要求和实际问题的需要，提出利用地震资料叠前数据进行二维波动方程反演，采用最小平方拟合修正模型参数的非线性反演方法，构造了问题的加速迭代算法．反演算法充分利用了冗余的叠前数据和多道相关性，可以分离噪声和信号，使噪声不参与或很少参与反演，算法抗噪能力强．数值模拟例子表明算法有效和稳定，得到了令人满意的结果．  相似文献