全站仪坐标导线的施测与平差探讨     

赵琴霞  法维刚 《测绘与空间地理信息》2011,34(5):242-245

提出了全站仪坐标导线外业施测时的检核方法和内业几种严密平差方法。  相似文献   

2010年早春浙江罕见连阴雨天气环流特征及成因分析   总被引：4，自引：0，他引：4  

张建海  曹艳艳 《高原气象》2011,30(6):1543-1553

利用客观分析资料分析了2010年早春浙江连阴雨天气的环流特征和热力、动力条件,并与历史同期天气状况进行了对比,结果表明：（1）乌拉尔山地区长波脊前偏北气流为连阴雨天气提供了冷空气条件,西太平洋副热带高压偏北偏西有利于其西北侧建立持久、稳定的水汽通道。（2）南北温差分布的变化导致高空西风急流出现分支,浙江位于北支急流南侧...  相似文献   

Optimal design of superelastic‐friction base isolators for seismic protection of highway bridges against near‐field earthquakes     

Osman E. Ozbulut  Stefan Hurlebaus 《地震工程与结构动力学》2011,40(3):273-291

The seismic response of a multi‐span continuous bridge isolated with novel superelastic‐friction base isolator (S‐FBI) is investigated under near‐field earthquakes. The isolation system consists of a flat steel‐Teflon sliding bearing and a superelastic NiTi shape memory alloy (SMA) device. The key design parameters of an S‐FBI system are the natural period of the isolated bridge, the yielding displacement of the SMA device, and the friction coefficient of the sliding bearings. The goal of this study is to obtain optimal values for each design parameter by performing sensitivity analysis of a bridge isolated by an S‐FBI system. First, a three‐span continuous bridge is modeled as two‐degrees‐of‐freedom with the S‐FBI system. A neuro‐fuzzy model is used to capture rate‐ and temperature‐dependent nonlinear behavior of the SMA device. Then, a set of nonlinear time history analyses of the isolated bridge is performed. The variation of the peak response quantities of interest is shown as a function of design parameters of the S‐FBI system and the optimal values for each parameter are evaluated. Next, in order to assess the effectiveness of the S‐FBI system, the response of the bridge isolated by the S‐FBI system is compared with the response of the non‐isolated bridge and the same bridge isolated by pure‐friction (P‐F) sliding isolation system. Finally, the influence of temperature variations on the performance of the S‐FBI system is evaluated. The results show that the optimum design of a bridge with the S‐FBI system can be achieved by a judicious specification of design parameters. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Implementation of a second‐order paraxial boundary condition for a water‐saturated layered half‐space in plane strain     

John L. Tassoulas 《地震工程与结构动力学》2011,40(5):531-550

A half‐space finite element and a transmitting boundary are developed for a water‐saturated layered half‐space using a paraxial boundary condition. The exact dynamic stiffness of a half‐space in plane strain is derived and a second‐order paraxial approximation of the stiffness is obtained. A half‐space finite element and a transmitting boundary are then formulated. The development is verified by comparison of the dynamic stiffness of impermeable and permeable rigid strip foundations with other published results. The advantage of using the paraxial boundary condition in comparison with the rigid boundary condition is examined. It is shown that the paraxial boundary condition offers significant gain and the resulting half‐space finite element and transmitting boundary can represent the effects of a water‐saturated layered half‐space with good accuracy and efficiency. In addition, the numerical method described herein maintains the strengths and advantages of the finite element method and can be easily applied to demanding problems of soil–structure interaction in a water‐saturated layered half‐space. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

VTI介质中准P波方程叠前逆时深度偏移   总被引：3，自引：0，他引：3       下载免费PDF全文

韩令贺  何兵寿  张会星 《地震学报》2011,33(2):209-218

根据具有垂直对称轴的横向各向同性（VTI）介质中的一阶准P波方程,导出了该方程在交错网格中逆时延拓的高阶有限差分格式,给出了其稳定性条件,采用完全匹配层吸收边界条件解决边界反射问题,分别应用下行波最大能量法和归一化互相关成像条件, 实现了VTI介质中准P波方程的叠前逆时深度偏移．各向异性Marmousi模型的试算结果表明,VTI介质准P波方程叠前逆时深度偏移算法不受地下构造倾角和介质横向速度变化的限制,对复杂模型具有良好的成像能力;应用归一化互相关成像条件能得到更好的成像效果．对比该模型的各向异性和各向同性逆时偏移剖面表明,在各向异性地区采集的纵波数据用各向异性偏移算法理论上能得到更好的成像结果．   相似文献   

地震数据模型优化过程方法及初步应用          下载免费PDF全文

杜军辉  闫丽莉  屈春燕  刘治  单新建 《地震地质》2011,33(3):706-718

由于地震数据种类繁多且数量不断增大,使得地震数据共享和数据服务面临的困难越来越大.针对这个问题,提出了基于PowerDesigner建模工具对已有的地震数据模型进行优化的过程方法.并将此方法初步应用于现有的1/400万活动断层GIS数据库中,针对该库目前存在的问题,实现了对断层数据模型的优化,结合具体的实例,应用了优化...  相似文献   

基于满意度的液体质量双调谐减振器参数优化及应用     

王波  汪正兴  陈开利  郭翠翠 《地震工程与工程振动》2011,31(6):186-190

为探讨多重液体质量双调谐阻尼器(MTLMD)参数优化算法,引入满意度理论,以满意度水平为目标函数,建立了主结构与MTLMD系统动力放大系数的三参量改进型加权满意度方程.对南京大胜关长江大桥吊杆结构MTLMD系统最优阻尼比及频率比等参数进行优化分析,得出了满意度水平、信心指数及最优参数之间的相互关系.研究结果表明:以满意...  相似文献   

山东Ⅱ、Ⅲ类场地地震动峰值加速度放大效应分析   总被引：1，自引：0，他引：1  

刁颋 《中国地震》2011,27(1):92-98

利用山东地区实测的Ⅱ类场地358个钻孔和Ⅲ类场地140个钻孔的地震动峰值加速度,计算了各个钻孔不同超越概率的土层地震动峰值加速度的放大系数ks,结果表明:(1)同类场地土层放大系数ks值总体符合正态分布,既有相对集中性,也有离散性;(2)随着基岩面输入地震动强度的增大,ks值降低,且Ⅲ类场地ks值降低较Ⅱ类的更为明显;(3)Ⅱ类场地随着基岩输入面埋深的增加,ks值呈增加趋势,约达20m深后基本趋于稳定,而Ⅲ类场地基岩输入面埋深的增加对ks值的影响不甚显著;(4)Ⅱ类场地50年超越概率10％的平均ks值(1.47)略高于《中国地震动参数区划图》使用的全国平均ks值.本文尝试讨论了山东地区Ⅱ、Ⅲ类场地不同强度基岩峰值加速度输入的ks调整值.  相似文献   

汶川8．0级特大地震汉源县震害特点与烈度异常成因探讨   总被引：1，自引：0，他引：1  

雷东宁  蔡永建  李恒  陈蜀俊 《四川地震》2011,(4):35-39

本文在汉源县地震灾害调查的基础上,通过收集前人在该区已取得的成果资料,采用综合分析、类比等方法,对汉源县地震烈度异常区震害及造成异常的原因进行了分析探讨。汉源县建筑物破坏形式以水平地震作用造成的“X”型剪切破坏为主,竖向地震造成的破坏较少。地震波传播路径、场地土层条件和地形地貌条件三者的耦合是造成汉源县烈度异常的主要原因,其中场地土层中占优势厚度的砾石层是造成场地地震波放大的主要内因。本文取得的初步结论为更加深入地科学研究本区地震烈度异常的原因提供了新思路。  相似文献   

A Method of Initial Vortex Relocation and Numerical Simulation Experiments on Tropical Cyclone Track   总被引：3，自引：2，他引：1  

袁金南  宋丽莉  黄燕燕  陈子通  刘春霞  丁伟钰 《热带气象学报(英文版)》2011,17(1):36-42

Using the technique of smooth filtering and cylindrical filtering, the initial vortex circulation and large-scale environmental field were separated from the background field. Then the separated initial vortex circulation was translated and reinserted in the location where it was observed. This led to the determination of a method of initial vortex relocation. For seven tropical cyclones at 23 points of measurement time in the years of 2006 and 2007, two schemes, either directly adding a tropical cyclone bogus model in the background or adding it after the relocation of the initial vortex in the background field, were employed. Simulation experiments were compared. The results showed that the mean errors of the simulated tropical cyclone tracks at 24 and 48 hours were both smaller with the scheme of adding tropical cyclone bogus model after the relocation of the initial vortex in the background field. The relocation method of the initial vortex decreases the error caused by the deviation of the initial tropical cyclone location in tropical cyclone models. The relocation method is conducive to improving the track forecast of tropical cyclone models and has a good perspective for operational application.  相似文献