Weak discontinuity in porous media: an enriched EFG method for fully coupled layered porous media     

M. Goudarzi  S. Mohammadi 《国际地质力学数值与分析法杂志》2014,38(17):1792-1822

In this paper, a series of multimaterial benchmark problems in saturated and partially saturated two‐phase and three‐phase deforming porous media are addressed. To solve the process of fluid flow in partially saturated porous media, a fully coupled three‐phase formulation is developed on the basis of available experimental relations for updating saturation and permeabilities during the analysis. The well‐known element free Galerkin mesh‐free method is adopted. The partition of unity property of MLS shape functions allows for the field variables to be extrinsically enriched by appropriate functions that introduce existing discontinuities in the solution field. Enrichment of the main unknowns including solid displacement, water phase pressure, and gas phase pressure are accounted for, and a suitable enrichment strategy for different discontinuity types are discussed. In the case of weak discontinuity, the enrichment technique previously used by Krongauz and Belytschko [Int. J. Numer. Meth. Engng., 1998; 41:1215–1233] is selected. As these functions possess discontinuity in their first derivatives, they can be used for modeling material interfaces, generating only minor oscillations in derivative fields (strain and pressure gradients for multiphase porous media), as opposed to unenriched and constrained mesh‐free methods. Different problems of multimaterial poro‐elasticity including fully saturated, partially saturated one, and two‐phase flows under the assumption of fully coupled extended formulation of Biot are examined. As a further development, problems involved with both material interface and impermeable discontinuities, where no fluid exchange is permitted across the discontinuity, are considered and numerically discussed. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Experimental study on retrofit of school buildings by adding sandwich columns to partition brick walls     

L. L. Chung  L. Y. Wu  K. H. Lien 《地震工程与结构动力学》2011,40(13):1417-1434

Thousands of buildings were damaged by the devastating Chi‐Chi earthquake on September 21, 1999. Of all the public buildings, school buildings are the most vulnerable to earthquake damage, and the retrofitting of existing school buildings becomes a stringent issue. In addition to cost effectiveness, the impact of retrofitting methods on the functions of the school buildings needs to be considered. This paper therefore proposes the retrofitting of school buildings by adding sandwich columns onto partition brick walls. The sandwich column is divided into two parts and is added to the two sides of the partition brick wall held with pairs of U‐shaped bars. The retrofit does not require the removal of windows or doors in the longitudinal direction making the proposed method cost effective and minimizes the impact on the function of the school buildings. Five full‐scale specimens without and with retrofitting were designed and fabricated for testing based on the partition brick wall frames of the existing school buildings. The specimens were subjected to cyclic loading in the out‐of‐plane direction through a loading frame so that the columns deformed with double curvatures. The experimental results verified the feasibility of the proposed retrofit method. The data showed that the lateral strength of the retrofitted specimen doubled that which was not and that the residual strength of the retrofitted specimen was just as high as the ultimate strength of the specimen without retrofitting. The analytical results in lateral strength yielded conservative figures compared with experimental measurements. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

华北地区极端温度MOS预报的季节划分   总被引：1，自引：1，他引：0       下载免费PDF全文

车钦  赵声蓉  范广洲 《应用气象学报》2011,22(4):429-436

针对极端温度MOS (Model Output Statistics) 预报中的季节划分问题,通过聚类分析方法以华北地区为例进行试验,在此基础上提出一种新的MOS温度预报方程季节分类方式:2月11日—3月20日和11月5日—12月4日定义为早春晚秋类,5月1日—9月30日定义为夏季类,3月21日—4月30日和10月1日—11月4日定义为晚春早秋类,12月5日—2月10日定义为冬季类。由于上述季节分类与传统的季节划分在3—5月和9—11月时间段存在较大差异,因此利用2009年进行试报,就两种时间分类进行对比分析。检验结果表明:利用新分类方法制作的极端温度MOS预报的整体效果好于传统的季节划分得到MOS极端温度预报效果,说明新的分类方式更适合于极端温度MOS预报。  相似文献   

A practical estimation of Clark IUH parameters using root selection and linear programming   总被引：1，自引：0，他引：1  

Kee‐Won Seong  Yong‐Hak Lee 《水文研究》2011,25(23):3676-3687

The values of the parameters of the Clark instantaneous unit hydrograph (IUH) are often relying on the subjective decision of the researcher, which leads to large variations of their values. Therefore, an objective method minimizing the subjective judgement in the IUH modelling procedure while providing a reduced range of acceptable values is proposed. The proposed method uses a basin average IUH to mitigate the robustness problem of the Clark IUH parameters. Using linear system theory, the z‐transform is applied to the average IUH and then the IUH polynomial is factored into the recession and time‐area curve (TAC) components based on a convolution relation between the Clark IUH parameters. During this calculation, the root selection method was adopted to verify the storage coefficient R from the recession component and a linear programming technique was applied for determining the TAC for the basin of interest. The Wi River basin was used to test the applicability of the proposed method. The results showed that the components of a single reservoir and the TAC for Clark IUH were separated effectively, and acceptable values for the parameters were obtained. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

宁夏香山群徐家圈组基本沉积单元   总被引：3，自引：0，他引：3  

李向东  何幼斌  罗进雄  李华  郑昭昌 《地质学报》2011,85(4):516-525

报道了宁夏香山群徐家圈组基本组成单元,即由细砂岩－粉砂岩－页岩构成的沉积序列,并将该沉积序列划分为密度流沉积层（Ⅰ）、牵引流沉积层（Ⅱ）和悬浮沉积层（Ⅲ）,进而探讨其成因。结果表明：①层Ⅰ主要由细砂岩和粉砂－细砂岩组成,且在不同厚度层之间无明显的粒度分异;②徐家圈组岩性系列中明显缺失细砂质粉砂岩,而这种缺失正好构成了层Ⅰ和层Ⅱ之间的粒度中断;③层Ⅱ发育两组交错层理,第一组是平行层理、准平行层理、复合流层理和小型丘状交错层理,第二组是单向交错层理、双向交错层理和平行层理;④层Ⅲ中的薄层泥晶石灰岩具有不平整的底面并在侧向上呈现出长的透镜状。结合相关的浊流沉积研究成果,综合分析上述结果,可得出以下结论：①层Ⅰ可能为具有高悬浮负载降落速率的高密度衰减流沉积形成;②层Ⅱ可能受内波、内潮汐作用的控制;③层Ⅲ可能以深海、半深海垂直降落沉积为主,并辅以缓慢的平流;④沉积时的浊流可能具有双层结构。  相似文献   

一种维护线状地物基本单元属性逻辑一致性的平差方法   总被引：1，自引：0，他引：1  

唐远彬  张丰  刘仁义  刘南 《武汉大学学报(信息科学版)》2011,(7):853-856,876

通过分析线状地物基本单元基本平差准则和方法,细化了变更行为并分析每一种变更类型的数据流向,设计并实现了一种能严格维护基本单元逻辑一致性的平差算法,并在实际应用系统中得到了验证。  相似文献   

附有相对权比的总体最小二乘平差   总被引：3，自引：1，他引：2  

王乐洋  许才军 《武汉大学学报(信息科学版)》2011,(8):887-890

推导了加权情况下附有相对权比的总体最小二乘平差方法,提出了确定相对权比的验前单位权方差法和目标函数最小化法。模拟算例表明,当观测值和系数矩阵的验前单位权方差已知且比较准确时,验前单位权方差法得到的结果与参数真值的差值范数最小;目标函数最小化法的目标函数估值最小,与参数真值的差别比验前单位权方差法的结果稍大。  相似文献   

CASIO fx—4850P计算器高程控制网按间接平差计算程序     

余志贵 《北京测绘》2011,(2):85-87,58

介绍了用CASIO fx—4850P计算器按间接法平差高程控制网,利用法方程中系数矩阵对称正定的特点,直接生成法方程式的系数矩阵。由于CASIO fx—4850P计算器程序容量28500字节,考虑到野外工作受环境制约及其工作的流动性,该计算器能够容纳一般的常用测量计算程序,携带和计算都非常方便。程序经过实例验算,精度很...  相似文献   

相位法激光测距信号源系统研究     

姜明富  曾一凡  杨艳 《测绘科学》2011,36(2):14-16

为了使相位式激光测距获得更好的调制信号源,采用了基于单片机控制DDA芯片AD9851产生频率可调,相位可控的信号源,由于DDS具有噪声低,频率分辨率高,易于编程等优点,根据实际需要,通过给AD9851编程获得不同的频率,满足不同距离的测量.由于获得的信号源中存在着高频杂散信号,设计了最接近理想特性的椭圆低通滤波器,并给...  相似文献   

基于灰色定权聚类的微观水驱油模型实验特低渗透储层流动单元划分及评价     

黄进腊  孙卫 《地质科技情报》2011,30(3):77-82

为研究微观水驱油模型流动单元划分及评价的可行性和效果,应用灰色定权聚类方法,以吴起油田X井区特低渗透长63储层25块样品为例,采用真实砂岩微观水驱油模型实验,以测得的渗透率、水驱前含油饱和度、启动压力、1 PV驱油效率以及孔隙度5项参数为基础,将样品划分为Ⅰ类、Ⅱ类和Ⅲ类流动单元.Ⅰ类、Ⅱ类和Ⅲ类流动单元分别与水下分流...  相似文献