近期准噶尔盆地西北部水利工程影响区土地利用变化特征分析   总被引：3，自引：1，他引：3  

李新琪  郭宇宏  王永嘉  马依尔 《干旱区地理》2003,26(3):269-273

噶尔盆地西北部水利工程设施的建成及运行，对工程沿线区域土地资源的利用方式产生了深远的影响。应用RS和GIS技术作为信息获取与分析工具。通过对噶尔盆地西北部水利工程沿线区域2000年和2002年Landsat TM卫星影像进行解析。对工程沿线区域土地利用现状及工程直接影响区土地利用动态变化特征进行系统分析。并探讨了土地利用变化的驱动因素。结合野外调查验证，文章还指出该区域由于土地利用方式的变化所引起的生态环境问题，并提出了相应的对策建议。  相似文献   

向海湿地孢粉记录及其环境意义   总被引：4，自引：2，他引：4  

王国平  张淑芹 《湿地科学》2003,1(1):57-62

以霍林河下游向海湿地为研究对象,通过对湿地垂直剖面的精细采样,将放射性核素精确计年与孢粉组合特征研究相结合,进行高分辨率剖析。研究结果表明:受沉积环境的影响,不同地表水力梯度与不同地貌单元的孢粉组合特征相差较大。典型剖面孢粉图式、A/C比值与麻黄属花粉丰度分析表明,该区域以草甸草原或草原景观为主,流域大环境以半干旱为特征,局部小环境为水流缓慢或静水沉积环境,并受到风沙的影响。240年以来虽然亦存在短暂的温湿期(1851-1861aA.D.及1890-1920aA.D.),但半干旱的气候特征始终没有改变。对照相邻区域研究成果,本区近代气候具有继承性和相似性。  相似文献   

Optimization with the Gradual Deformation Method   总被引：1，自引：0，他引：1  

Mickaële Le Ravalec-Dupin  Benoît Ntinger 《Mathematical Geology》2002,34(2):125-142

Building reservoir models consistent with production data and prior geological knowledge is usually carried out through the minimization of an objective function. Such optimization problems are nonlinear and may be difficult to solve because they tend to be ill-posed and to involve many parameters. The gradual deformation technique was introduced recently to simplify these problems. Its main feature is the preservation of the spatial structure: perturbed realizations exhibit the same spatial variability as the starting ones. It is shown that optimizations based on gradual deformation converge exponentially to the global minimum, at least for linear problems. In addition, it appears that combining the gradual deformation parameterization with optimizations may remove step by step the structure preservation capability of the gradual deformation method. This bias is negligible when deformation is restricted to a few realization chains, but grows increasingly when the chain number tends to infinity. As in practice, optimization of reservoir models is limited to a small number of iterations with respect to the number of gridblocks, the spatial variability is preserved. Last, the optimization processes are implemented on the basis of the Levenberg–Marquardt method. Although the objective functions, written in terms of Gaussian white noises, are reduced to the data mismatch term, the conditional realization space can be properly sampled.  相似文献   

水工混凝土配合比选择初探     

程海清 《四川地质学报》2002,22(Z1):31-33

介绍了为保证水工隧道混凝土浇注质量所采用的方法，分析了水、水泥、砂子、石子四种材料用量之间的关系，探索出了确定水泥最优用量的一些方法。  相似文献   

城市人口GIS中数据的不确定性研究   总被引：8，自引：0，他引：8  

柳宗伟  王新洲  陈顺清 《武汉大学学报(信息科学版)》2002,27(6):627-631

针对系统数据源、数据模型的不确定性以及分析过程中引入的不确定性等问题进行了系统的研究，并归纳了各种不确定性的影响模型，进而提出了一套人口GIS数据优化建模以及分析过程中人口密度中心建模的思想和实用方法，用于克服人口GIS中数据的不确定性的影响。  相似文献   

Land Use Structure Optimization Under Systematic Framework     

LIU Yanfang HUANG Liangprofessor  School of Resource  Environment Science  Wuhan University  Luoyu Road  Wuhan  China. 《地球空间信息科学学报》2002,5(3):46-52

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｙｓｔｅｍｏｆｌａｎｄｕｓｅｉｓａｖｅｒｙｃｏｍｐｌｅｘｓｙｓｔｅｍ .Ｗｅｄｒａｗｕｐｔｈｅｐｒｏｊｅｃｔｏｆｌａｎｄｕｓｅｐｌａｎｎｉｎｇｓｔｒｕｃｔｕｒｅｔｏｉｍｐｌｅｍｅｎｔｔｈｅｏｐｔｉ ｍｉｚａｔｉｏｎｏｆｌａｎｄｒｅｓｏｕｒｃｅｓ .Ｔｈｅｏｐｔｉｍｉｚａｔｉｏｎｏｆｌａｎｄｕｓｅｓｔｒｕｃ ｔｕｒｅｉｓｔｈｅｋｅｒｎｅｌｏｆｌａｎｄｕｓｅｐｌａｎｎｉｎｇ .Ｔｏｄａｙ,ｍｏｓｔｏｆｔｈｅｕｒｂａｎｌａｎｄｕｓｅｐｌａｎｓｏｎｌｙｃｏｎｓｉｄｅｒｔｈｅｏｐ…  相似文献   

Optimization of Land Use Structure Based on Ecological GREEN Equivalent   总被引：1，自引：0，他引：1  

LIU  Yanfnag  MING  Dongping 《地球空间信息科学学报》2002,5(4):60-67

Optimization of land use structure consists of economic and social and ecological optimization.Applying the minds of system engineering and principles of ecology,this paper presents such thoughts:the optimal forest-coverage rate calculated according to the reality of a district is set as main standard of ecological rationality in the district;through considering the value of ecosystem services of the land with GREEN equivalent(mainly cultivated land and grassland)and based on the rule GREEN equivalent,this paper introduces the area conversion between woodland and cultivated land ,also between woodland and grassland;this paper establishes a multi-dimension controlling model of optimization of land use structure,In addition,a multiobjective linear programming model for optimization of land use structure is designed.In the end,this paper tests and verifies this theory of ecological optimization,taking Qionghai city in Hainan Province as an example.  相似文献   

Obtaining refined first‐order predictive models of linear structural systems     

Hilmi Lu  Raimondo Betti  Richard W. Longman 《地震工程与结构动力学》2002,31(7):1413-1440

This study presents an effective method for identifying predictive models and the underlying modal parameters of linear structural systems using only measured output and excitation time histories obtained from dynamic testing. The system under examination is modelled as a first‐order multi‐input multi‐output time‐invariant system, and the structural model is realized using the Eigensystem Realization Algorithm together with the Observer/Kalman filter IDentification algorithm. The identified state‐space model is further refined using a non‐linear optimization technique based on sequential quadratic programming. The numerical examples show that the developed methodology performs very well even in the presence of inadequate instrumentation and measurement noise, and that the methodology is highly capable of creating realistic predictive models of structural systems, as well as estimating their underlying modal parameters. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

单裂隙面渗流特性及等效水力隙宽   总被引：23，自引：0，他引：23       下载免费PDF全文

王媛  速宝玉 《水科学进展》2002,13(1):61-68

首先讨论了描述单裂隙面几何特性的两个最基本参数——隙宽和粗糙性的确定方法,系统地总结和分析了现有有关单裂隙面渗流特性方面的研究成果,并对不同粗糙性描述下的裂隙等效水力隙宽的确定问题进行了探讨,提出了自已的看法,并指出进一步要解决的问题。  相似文献   

网状河流研究进展述评   总被引：6，自引：2，他引：6  

王随继  谢小平  程东升 《地理科学进展》2002,21(5):440-449

网状河流作为一种新的冲积河流类型已经引起地貌学家、水利学家和沉积学家的关注 ,成为河流地貌领域、河流沉积领域以及河流水动力领域的研究热点之一。本文在介绍网状河流基本概念的基础上 ,综合国内外的研究成果 ,从河流的平面形态、边界条件、沉积特征、水动力条件以及在河型演化序列中的位置等方面 ,对网状河流的研究进展作一较全面的述评 ,并指出目前研究的薄弱环节 ,以利于研究者把握网状河流的研究现状 ,并推动对网状河流的进一步探讨。  相似文献