计算机辅助绘制流域等流时线   总被引：4，自引：0，他引：4  

王腊春  陈晓玲 《地理科学》1996,16(2):184-190

采用地理信息系统方法，对流域的地形地貌特征进行分析，模拟水质点在流域上的运动轨迹，并根据水质点汇流时间与汇流路径，坡度，坡长的关系，建立了流域汇流等流时线模型，经实例验证，效果较好。  相似文献   

屈曲约束支撑滞回曲线模型和刚度方程的建立   总被引：3，自引：0，他引：3  

李国强  胡宝琳 《地震工程与工程振动》2007,27(2):26-31

针对屈曲约束支撑，本文根据其反复荷载作用下的滞回特征，提出了一种滞回模型，并建立了屈曲约束支撑的弹塑性刚度方程。根据这种模型编制程序模拟绘制了屈曲约束支撑的滞回曲线，将模拟计算曲线与试验所得曲线进行对比，对比结果表明本文所提模型是准确、有效的。  相似文献   

建筑抗震构件中屈曲约束支撑结构研究新进展          下载免费PDF全文

陈剑波  完海鹰 《地震工程学报》2020,42(5):1289-1302

详细介绍了近年来中国学者在屈曲约束支撑研究方面取得的研究成果，着重讨论了屈曲约束支撑构件（核心单元、约束机构、无黏结构造层）和整体抗震性能以及设计方法的研究现状。结果表明：屈曲约束支撑以其良好的耗能性能具有很好的发展潜力，屈曲约束支撑的适用范围不断拓展，结构形式更趋多样化，设计方法不断优化。  相似文献   

Robust biased estimation and its applications in geodetic adjustments   总被引：6，自引：0，他引：6  

Q. Gui  J. Zhang 《Journal of Geodesy》1998,72(7-8):430-435

In this paper, a number of robust biased estimators (e.g. ordinary robust ridge estimator, robust principal components estimator, robust combined principal components estimator, robust single-parametric principal components estimator, robust root-root estimator) are established by means of a unified expression of biased estimators and based on the principle of equivalent weight. The most attractive advantage of these new estimators is that they can not only overcome the ill-conditioning of the normal equation but also have the ability to resist outliers. A numerical example is used to illustrate that these new estimators are much better than the least-squares estimator and various biased estimators even when both ill-conditioning and outliers exist. Received: 14 November 1995/Accepted: 11 February 1998  相似文献   

复杂地质条件下气层的多参数识别   总被引：1，自引：0，他引：1  

张小莉  冯乔 《地球物理学进展》1998,13(3):56-62

在复杂地质条件下,应用单一或两种孔隙测井资料直接识别气层,灵敏度不高,为了准确地识别复杂地质条件下的气层,需从不同角度,应用多参数进行综合识别,本文介绍了声波法,中子－密度法,双孔隙度法,中子－伽玛法,等效弹性模量法等,并应用它们对哈盆地两口井进行了重点分析,效果良好。  相似文献   

P-P波及P-SV波叠前深度偏移速度模型建立方法   总被引：11，自引：1，他引：10       下载免费PDF全文

李录明  罗省贤 《地球物理学报》1998,41(Z1):305-318

针对多波叠前深度偏移速度模型的建立问题,提出在CDP道集上利用互换原理组成伪地集作为叠前偏移速度分析的数据道集,先用叠前时间偏移方法求取层间互不影响的等效偏移速度模型,再用餐前深度偏移方法逐层求取层速度模型．对各层的速度质量、整个速度模型层位结构及速度横向变化,采用人机交互方式进行监控,并在速度叠代中引入全局寻优的遗传算法,使整个速度模型建立过程具有稳定、可靠和可视化的优点．经理论和实际资料处理结果证明,本方法是行之有效的．  相似文献   

带横隔板局部开孔沉箱在斜向波作用下的受力研究          下载免费PDF全文

刘勇  李玉成  滕斌  吴浩 《海洋学报》2008,30(2):137-146

基于线性势流假定,对斜向波作用下带横隔板局部开孔沉箱防波堤的水平波浪力进行了理论研究。给出了开孔沉箱法向水平力和横隔板受力的理论计算方法,在极限情况下波浪力的计算结果与文献中的已有结果一致。利用数值算例分析了开孔沉箱总水平力的主要影响因素。开孔沉箱法向总水平力的减小主要集中于结构上半部分波浪影响范围以内。增加单个开孔沉箱的长度有利于减小结构所受总水平波浪力。当波浪入射角或沉箱前开孔墙孔隙影响系数幅值较大时,开孔沉箱横隔板上总水平力的最大值要超过相应的沉箱法向总水平力,此时要注意横隔板的强度问题。  相似文献   

Effects of brace stiffness on performance of structures with supplemental Maxwell model‐based brace–damper systems     

Yung‐Tsang Chen  Y. H. Chai 《地震工程与结构动力学》2011,40(1):75-92

Shear‐type buildings with Maxwell model‐based brace–damper systems are studied in this paper with a primary emphasis on the effects of brace stiffness. A single‐story building with a viscous damper installed on top of a Chevron‐brace is first investigated. Closed‐form solutions are derived for the simple structure, relating the brace stiffness and damper coefficient to the targeted reduction in response displacement or acceleration. For a given brace stiffness, the solution is minimized to give a set of formulae that will allow the optimal damper coefficient to be determined, assuring the desired performance. The model is subsequently extended to multistory buildings with viscous dampers installed on top of Chevron‐braces. For a targeted reduction in the mean square of the interstory drift, floor acceleration or base shear force, the minimum brace stiffness and optimal damper coefficients are obtained through an iterative procedure. The response reduction, which signifies the improved performance, is achieved by a combination of brace stiffness and viscous damper coefficients, unlike conventional approaches where damper coefficients are typically optimized independent of brace stiffnesses. Characteristics of multi‐degree‐of‐freedom systems are studied using a 2‐story and a 10‐story buildings where the effects of brace stiffness on the overall performance of the building can be quantified. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Effective block diagonal preconditioners for Biot's consolidation equations in piled‐raft foundations     

K. B. Chaudhary  K. K. Phoon  K. C. Toh 《国际地质力学数值与分析法杂志》2013,37(8):871-892

The finite element (FE) simulation of large‐scale soil–structure interaction problems (e.g. piled‐raft, tunnelling, and excavation) typically involves structural and geomaterials with significant differences in stiffness and permeability. The symmetric quasi‐minimal residual solver coupled with recently developed generalized Jacobi, modified symmetric successive over‐relaxation (MSSOR), or standard incomplete LU factorization (ILU) preconditioners can be ineffective for this class of problems. Inexact block diagonal preconditioners that are inexpensive approximations of the theoretical form are systematically evaluated for mitigating the coupled adverse effects because of such heterogeneous material properties (stiffness and permeability) and because of the percentage of the structural component in the system in piled‐raft foundations. Such mitigation led the proposed preconditioners to offer a significant saving in runtime (up to more than 10 times faster) in comparison with generalized Jacobi, modified symmetric successive over‐relaxation, and ILU preconditioners in simulating piled‐raft foundations. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

RESOLUTION OF MULTICOMPONENT FLUORESCENT MIXTURES BY ANALYSIS OF THE EXCITATION-EMISSION-FREQUENCY ARRAY     

DONALD S.BURDICK XIN M.TU Institute of Statistics  Decision Sciences  Department of Mathematics Duke University  Durham  NC  U.S.A.LINDA B.MCGOWN DAVID W.MILLICAN Department of Chemistry  Drake University  Durham  NC  U.S.A. 《地理学报(英文版)》1990,(1)

Fluorescence lifetime provides a third independent dimension of information for the resolution of totalluminescence spectra of multicomponent mixtures.The incorporation of this parameter into theexcitation-emission matrix(EEM)by the phase modulation technique results in a three-dimensionalexcitation-emission-frequency array (EEFA).Multicomponent analysis based on the three-dimensionalEEFA brings a qualitative change for the resolved spectra,i.e.individual spectra can be uniquely resolved,which is impossible with any two-dimensional analysis.In this paper we present a method for analyzingthe EEFA.We show mathematically that with the three-dimensional analysis of the EEFA individualspectra and lifetimes can be obtained.Our algorithm is developed in mathematical detail and isdemonstrated by its application to a two-component mixture.  相似文献