龙首二级面板堆石坝三维真非线性地震反应分析和评价     

赵剑明  常亚屏  陈宁 《岩土力学》2004,25(Z2):388-392

基于土石料三维粘弹塑性动力本构模型,并采用新型三维各向异性有厚度薄单元来模拟面板和堆石的接触面特性,建立了高面板堆石坝地震反应分析的三维真非线性动力分析方法.利用坝料动力特性的大型三轴试验成果,分析计算了龙首二级(西流水)面板堆石坝的地震反应,主要包括加速度反应、堆石体应力反应及坝体单元抗震安全系数、面板应力反应和变形及接缝位移、高趾墙动力反应等.为大坝的抗震设计提供了有力的技术依据.  相似文献   

基于EM算法和单幅雷达图像阴影的控制点坡度校正   总被引：1，自引：0，他引：1  

钱俊  舒宁 《武汉大学学报(信息科学版)》2004,29(12):1089-1092

对在我国现有的条件下进行控制点坡度校正的必要性进行了阐述，并分析了EM算法。根据EM算法以及基于区域增长的余弦散射模型建立了控制点坡度校正模型，并用河北省张北地区的雷达影像进行了实验，取得了较高的精度初值。  相似文献   

基于光谱空间密度分析的边缘提取     

刘楠  舒宁 《武汉大学学报(信息科学版)》2004,29(12):1093-1096

针对传统的边缘提取方法大部分不适应高光谱数据的特点，提出了基于光谱空间密度分析边缘提取的思想。在分组主分量变换提取第一主分量作为特征维的基础上，采用面向对象的二次判别边缘的方法，通过立体判决将光谱空间中低密度超椭球体集群视为真实边缘点集群。试验表明，此方法是合理可行的。  相似文献   

Impact of inner core rotation on outer core flow: the role of outer core viscosity     

J. Y. Guo  P. M. Mathews  Z. X. Zhang  J. S. Ning 《Geophysical Journal International》2004,159(1):372-389

  相似文献   

GFC-120型自走式反循环钻机的研制          下载免费PDF全文

张西坤  宋秋锋  杨杰  张军  李建民 《探矿工程》2005,32(12):35-37

GFC-120型钻机为自走式动力头回转反循环钻机，用于降水井和护坡桩基础孔以及小型水井的施工。介绍了其性能特点、主要技术参数、结构及工作原理。  相似文献   

Discussion on influence of cavern’s span on surrounding rock classification     

ZHOU Jian-min  JIN Feng-nian  WANG Bin  ZHAO Pei-sheng 《岩土力学》2005,26(Z1):303-305

The influence of cavern’s span on surrounding rock classification is getting more and more recognition along with large span underground working’s increasingly coming forth. The authors analyse the timbering expense of cavern in jointed rock mass, the radius of plastic loosened zone and the size effect of macroscopical mechanical parameters of rock mass. Based on the complexion of depressing of surrounding rock’s stability due to increment of cavern’s span, the authors pinpoint attaching importance to the influence of cavern’s span on surrounding rock classification; and suggest reckoning the factor of cavern’s span in surrounding rock classification scientifically by studying the size effect of rock mass’s physico-mechanical parameters.  相似文献   

松花江上游地区汞污染的化学生态效应   总被引：5，自引：0，他引：5  

王宁  朱颜明  朴明玉  孟丹 《地理科学》2005,25(6):737-741

采样分析了吉林省东部松花江上游金矿开采区及其附近水、土壤、动植物及河流沉积物样品中汞的含量，发现河流沉积物中汞的污染相当严重；受其影响当地的植物和两栖类动物——中国林蛙体内总汞和甲基汞含量也明显高于对照组。实验表明，林蛙内脏对汞的富集能力大于肌肉；秋季对汞的富集大于春季；河流沉积物中甲基汞的含量与林蛙体内甲基汞的含量有较好的正相关。汞污染的来源与区域内个体金矿的滥采滥排有直接关系，表明人类活动所产生的有毒重金属在地表过程中出现了化学生态效应。  相似文献   

Validating the ability of the discontinuous deformation analysis method to model normal P‐wave propagation across rock fractures          下载免费PDF全文

Wenjun Gong  Yunsheng Wang  Youjun Ning  Yonghong Luo  Yujie Wang 《国际地质力学数值与分析法杂志》2017,41(10):1267-1282

The effects of fractures on wave propagation problems are increasingly abstracting the attention of scholars and engineers in rock engineering field. This study aims to fully validate the ability of discontinuous deformation analysis (DDA) to model normal P‐wave propagation across rock fractures. The effects of a single fracture and multiple parallel fractures are all tested. The results indicate that DDA can accurately reflect the fracture effects, including the fractures stiffness, the fracture spacing and the fracture number, and the effects of incident wave frequency on one‐dimensional P‐wave propagation problems. Thus, DDA is able to deal well with normal incident P‐wave propagation problems. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Effects of temporal scales and space mismatches on the TRMM 3B42 v7 precipitation product in a remote mountainous area          下载免费PDF全文

Shiva Ebrahimi  Cheng Chen  Qiuwen Chen  Yinsheng Zhang  Ning Ma  Qammerul Zaman 《水文研究》2017,31(24):4315-4327

The accurate measurement of precipitation is essential to understanding regional hydrological processes and hydrological cycling. Quantification of precipitation over remote regions such as the Tibetan Plateau is highly unreliable because of the scarcity of rain gauges. The objective of this study is to evaluate the performance of the satellite precipitation product of tropical rainfall measuring mission (TRMM) 3B42 v7 at daily, weekly, monthly, and seasonal scales. Comparison between TRMM grid precipitation and point‐based rain gauge precipitation was conducted using nearest neighbour and bilinear weighted interpolation methods. The results showed that the TRMM product could not capture daily precipitation well due to some rainfall events being missed at short time scales but provided reasonably good precipitation data at weekly, monthly, and seasonal scales. TRMM tended to underestimate the precipitation of small rainfall events (less than 1 mm/day), while it overestimated the precipitation of large rainfall events (greater than 20 mm/day). Consequently, TRMM showed better performance in the summer monsoon season than in the winter season. Through comparison, it was also found that the bilinear weighted interpolation method performs better than the nearest neighbour method in TRMM precipitation extraction.  相似文献   

Real-time retrieval of precipitable water vapor from GPS and BeiDou observations   总被引：3，自引：2，他引：1  

Cuixian Lu  Xingxing Li  Tobias Nilsson  Tong Ning  Robert Heinkelmann  Maorong Ge  Susanne Glaser  Harald Schuh 《Journal of Geodesy》2015,89(9):843-856

  相似文献