基于水稻特征波段的决策树分类研究   总被引：1，自引：0，他引：1  

李杨  江南  吕恒  张瑜  苗翠翠  王妮 《地理与地理信息科学》2010,26(2)

针对种植结构复杂、地形复杂的水稻种植面积遥感提取精度不高现象,结合多时相遥感影像中反映水稻物候规律的特征波段,以南京江宁丘陵山区为例,选择典型水稻物候期时相的TM数据,基于多特征波段构建决策树分类提取水稻种植面积。结果表明:纹理、植被指数、湿度因子、坡度因子等多特征参与决策树分类能够提高总体精度;在具有两期物候数据时提取精度和效率较好,而加入了地形特征的水稻抽穗期数据比水稻灌浆期数据获取效果略好。因此,利用合理的作物物候期数据和该遥感影像的特征波段可有效提高分类精度,为地块破碎区作物种植面积提取提供有效手段。  相似文献   

中国海岛县(区)产业结构演进研究   总被引：2，自引：1，他引：1  

孙兆明  马波 《地域研究与开发》2010,29(3)

海岛可持续发展的核心问题之一是产业结构优化和主导产业选择。通过对我国海岛县(区)三次产业相对竞争能力、产业结构与经济增长关系的分析,认为其产业结构层次低,竞争力弱,地域经济系统呈现经济脆弱性、环境脆弱性和社会脆弱性相互交织的状态。海岛经济发展必须以海岛生态环境的承载许可为前提,不存在统一的产业结构演进目标。海岛县(区)需要在市场开放、产业转移以及区域发展一体化的推动下,优化产业分工,稳定发展第一产业,有限发展第二产业,优先发展第三产业;在海洋生物资源、港口资源、旅游资源、空间资源等共同开发的基础上,因岛制宜,培育竞争能力强、生态环境友好型的主导产业。  相似文献   

Simplified inelastic seismic analysis of base‐isolated structures using the N2 method     

Vojko Kilar  David Koren 《地震工程与结构动力学》2010,39(9):967-989

In the paper a simplified nonlinear method has been applied to the analysis of base‐isolated structures. In the first part, a three‐linear idealization of the capacity curve is proposed. The initial stiffness is defined based on the first yielding point in the superstructure, whereas the secondary slope depends on the failure mechanism of the superstructure. A consequence is a much more pronounced secondary slope, which does not correspond to the presumptions used in the originally proposed N2 method. A parametric nonlinear dynamic study of single degree of freedom systems with different hardening slopes and damping has been performed for an ensemble of seven EC8 spectrum‐compatible artificial accelerograms. It was concluded that, in the long‐period range, the equal displacement rule could be assumed also for the proposed systems with non‐zero post‐yield stiffness. In the second part, the proposed idealization was used for the analysis of isolated RC frame buildings that were isolated with different (lead) rubber‐bearing isolation systems. The stiffness of the isolators was selected for three different protection levels and for three different ground motion intensities, which have resulted in elastic as well as moderately and fully damaged superstructure performance levels. Three different lateral load distributions were investigated. It was observed that a triangular distribution, with an additional force at the base, works best in the majority of practical cases. It was concluded that the N2 method can, in general, provide a reasonably accurate prediction of the actual top displacement, as well as of the expected damage to the superstructure. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

岩溶水饮用水水源保护区划分技术方法——以邯郸市羊角铺水源地为例   总被引：1，自引：1，他引：0  

翟立娟 《中国岩溶》2011,30(1):47-52

位于峰峰矿区内的羊角铺水源地日开采奥陶系岩溶地下水达为9万m3,为一个大型的水源地。参照《饮用水水源保护区划分技术规范》大型水源地保护区范围确定应采用数值模型模拟计算的规定要求,本文根据羊角铺水源所在地下水系统的水文地质特征,结合模型技术的要求,利用目前国际上流行的visual modflow软件,采用数值模拟法对地下水系统的溶质运移进行模拟预测,并据之确定出羊角铺水源地不同级别的保护区范围,具体是:以水源地地下水开采井为中心,溶质质点迁移100天的距离为半径所圈定的范围作为水源地一级保护区范围,溶质质点迁移1000天的距离为半径所圈定且除去一级保护区以外的范围为二级保护区,将水源地所在的岩溶水子系统的奥陶系灰岩裸露补给区范围划定为准保护区范围。   相似文献   

永久散射体点目标提取方法研究     

龙四春  李陶  冯涛 《大地测量与地球动力学》2011,31(4):144-148

分析幅度稳定性、相位稳定性、时序相关性及振幅离差阈值等多种PS点提取方法的特点与缺陷,提出基于时序相关系数阈值与振幅离差阈值并集和交集的PS点识别策略,给出其相应模型,并实例验证了该方法的有效性与优越性。  相似文献   

一种卫星遥感图像目标位置快速精校正的新方法   总被引：2，自引：1，他引：2  

汤亚波  徐守时 《遥感学报》2005,9(6):653-658

从遥感图像目标识别处理等应用特点出发,提出一种卫星图像目标位置精校正的新方法。直接在系统级几何校正的遥感图像上检测目标及其附近的地面控制点,然后进行异常控制点检测,最后利用正常控制点对目标地理位置实施精校正。同时提出一种基于局部区域最大团的异常控制点自动检测方法。实验结果表明,所述方法在保证目标定位精度的同时,可显著提高目标地理位置精校正的速度。  相似文献   

双王含金角砾岩带形成机制分析及进一步找矿靶区预测     

闵全收  朱德鹏  郭君  芦正艳 《地质力学学报》2016,22(2):285-293

基于前人的地质资料,结合矿床实际地质情况,对陕西省太白双王金矿床含金角砾岩带的形成机制进行了推演,认为双王含金角砾岩是构造与热液隐爆作用相结合的产物。另外对双王金矿床不同期次角砾岩的含金性、不同标型黄铁矿的含金性及双王金矿床金矿化富集规律等进行了研究和总结,并对双王金矿下一步勘查靶区进行了预测。   相似文献   

The effect of causal parameter bounds in PSHA‐based ground motion selection          下载免费PDF全文

Karim Tarbali  Brendon A. Bradley 《地震工程与结构动力学》2016,45(9):1515-1535

In this paper the effect of causal parameter bounds (e.g. magnitude, source‐to‐site distance, and site condition) on ground motion selection, based on probabilistic seismic hazard analysis (PSHA) results, is investigated. Despite the prevalent application of causal parameter bounds in ground motion selection, present literature on the topic is cast in the context of a scenario earthquake of interest, and thus specific bounds for use in ground motion selection based on PSHA, and the implications of such bounds, is yet to be examined. Thirty‐six PSHA cases, which cover a wide range of causal rupture deaggregation distributions and site conditions, are considered to empirically investigate the effects of various causal parameter bounds on the characteristics of selected ground motions based on the generalized conditional intensity measure (GCIM) approach. It is demonstrated that the application of relatively ‘wide’ bounds on causal parameters effectively removes ground motions with drastically different characteristics with respect to the target seismic hazard and results in an improved representation of the target causal parameters. In contrast, the use of excessively ‘narrow’ bounds can lead to ground motion ensembles with a poor representation of the target intensity measure distributions, typically as a result of an insufficient number of prospective ground motions. Quantitative criteria for specifying bounds for general PSHA cases are provided, which are expected to be sufficient in the majority of problems encountered in ground motion selection for seismic demand analyses. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Risk‐based seismic design for collapse safety          下载免费PDF全文

Nuša Lazar Sinković  Marko Brozovič  Matjaž Dolšek 《地震工程与结构动力学》2016,45(9):1451-1471

Risk‐based seismic design, as introduced in this paper, involves the use of different types of analysis in order to satisfy a risk‐based performance objective with a reasonable utilization rate and sufficient reliability. Differentiation of the reliability of design can be achieved by defining different design algorithms depending on the importance of a structure. In general, the proposed design is iterative, where the adjustment of a structure during iterations is the most challenging task. Rather than using automated design algorithms, an attempt has been made to introduce three simple guidelines for adjusting reinforced concrete frames in order to increase their strength and deformation capacity. It is shown that an engineer can design a reinforced concrete frame in a few iterations, for example, by adjusting the structure on the basis of pushover analysis and checking the final design by means of nonlinear dynamic analysis. A possible variant of the risk‐based design algorithm for the collapse safety of reinforced concrete frame buildings is proposed, and its application is demonstrated by means of an example of an eight‐storey reinforced concrete building. Four iterations were required in order to achieve the risk‐based performance objective with a reasonable utilization rate. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

基于场地特征周期的瑞利阻尼确定方法     

丁海平  马俊玲 《岩土力学》2013,34(Z2):35-40

从地震影响系数曲线的特征周期 出发,提出了分别取 和 作为时域计算瑞利(Rayleigh)阻尼的两个目标频率。通过3种不同厚度的单一土层和1种多层土层模型在3条不同地震动作用下的计算,比较了基于Annie方法和本文方法确定Rayleigh阻尼的时域解,以及基于等效线性化的频域解,结果表明：两种Rayleigh阻尼形式的地表加速度峰值误差都在10%以内,地表加速度反应谱基本一致,但本文方法对土层厚度和输入的地震动不太敏感,即误差随着土层厚度及输入地震动的不同离散性很小,且应用更为简便,无需求土层的自振频率,只需要根据场地类别获得场地特征周期,就可确定Rayleigh阻尼值。  相似文献