运用GVF Snake算法提取水域的不规则边界   总被引：1，自引：1，他引：0  

朱述龙  孟伟灿  朱宝山 《遥感学报》2013,17(4):742-758

GVF Snake是一种改进型主动轮廓提取算法。本文在详细介绍GVF Snake原理的基础上,重点对GVF Snake的内、外部约束力在边界提取中的作用以及初始边界对提取结果的影响进行了实验研究,提出了初始边界和内部约束力权值的合理设置方法,设计并实现了交互式GVF Snake算法,并用于提取遥感影像上水域的不规则边界。该算法采用种子点区域生长法自动给出水域的初始边界,采用人机交互法设置内部约束力权值,然后运用GVF Snake算法搜索水域的实际边界。实验表明：对于形状极不规则的水域,交互式GVF Snake算法也能方便、快速、准确地获取其边界。  相似文献   

Magnetic detection method for seabed cable in marine engineering surveying     

Bo Yu  Yanchun Liu  Guojun Zhai  Gang Bian  Fumin Xiao 《地球空间信息科学学报》2013,16(3):186-190

The detection and identification of the seabed cable is becoming an important task in the marine engineering. The features of the magnetic anomaly can be used to detect the existence of the seabed cable. The magnetic field model is presented, and the consistency of the magnetic anomaly distribution between the simulation of the model and the observed data is verified. The comparison shows that the seabed cable can be effectively detected and identified with reasonable method.  相似文献   

The decision of the optimal parameters in Markov random fields of images by genetic algorithm     

Zheng Zhaobao  Zheng Hong 《地球空间信息科学学报》2013,16(3):14-18

This paper introduces the principle of genetic algorithm and the basic method of solving Markov random field parameters. Focusing on the shortcomings in present methods, a new method based on genetic algorithms is proposed to solve the parameters in the Markov random field. The detailed procedure is discussed. On the basis of the parameters solved by genetic algorithms, some experiments on classification of aerial images are given. Experimental results show that the proposed method is effective and the classification results are satisfactory.  相似文献   

A new method for indentifying the model error of adjustment system     

Tao Benzao  Zhang Chaoyu 《地球空间信息科学学报》2013,16(3):189-192

Some theory problems affecting parameter estimation are discussed in this paper. Influence and transformation between errors of stochastic and functional models is pointed out as well. For choosing the best adjustment model, a formula, which is different from the literatures existing methods, for estimating and identifying the model error, is proposed. On the basis of the proposed formula, an effective approach of selecting the best model of adjustment system is given.  相似文献   

黄河和长江沉积角闪石亲石元素地球化学特征对比与物源辨识     

金秉福  党丽丽  孔庆祥  王孟瑶  岳伟  樊水淼 《沉积学报》2022,40(1):149-165

为辨识黄河和长江入海沉积物中角闪石的物源差异,对采自黄河口段、长江口段以及废黄河口和苏北沿岸,共26个样点、38组粒度粗细不同的碎屑角闪石进行了矿物元素地球化学测试,获得了这些角闪石群体的50种常量和微量元素含量值.结果表明:不同粒级测量的同源角闪石元素含量除少数大离子活泼元素相对偏差较大之外,大部分元素含量差异性较小...  相似文献   

Identification of Convective and Stratiform Clouds Based on the Improved DBSCAN Clustering Algorithm     

Yuanyuan ZUO  Zhiqun HU  Shujie YUAN  Jiafeng ZHENG  Xiaoyan YIN  Boyong LI 《大气科学进展》2022,39(12):2203-2212

A convective and stratiform cloud classification method for weather radar is proposed based on the density-based spatial clustering of applications with noise (DBSCAN) algorithm. To identify convective and stratiform clouds in different developmental phases, two-dimensional (2D) and three-dimensional (3D) models are proposed by applying reflectivity factors at 0.5° and at 0.5°, 1.5°, and 2.4° elevation angles, respectively. According to the thresholds of the algorithm, which include echo intensity, the echo top height of 35 dBZ (ET), density threshold, and ε neighborhood, cloud clusters can be marked into four types: deep-convective cloud (DCC), shallow-convective cloud (SCC), hybrid convective-stratiform cloud (HCS), and stratiform cloud (SFC) types. Each cloud cluster type is further identified as a core area and boundary area, which can provide more abundant cloud structure information. The algorithm is verified using the volume scan data observed with new-generation S-band weather radars in Nanjing, Xuzhou, and Qingdao. The results show that cloud clusters can be intuitively identified as core and boundary points, which change in area continuously during the process of convective evolution, by the improved DBSCAN algorithm. Therefore, the occurrence and disappearance of convective weather can be estimated in advance by observing the changes of the classification. Because density thresholds are different and multiple elevations are utilized in the 3D model, the identified echo types and areas are dissimilar between the 2D and 3D models. The 3D model identifies larger convective and stratiform clouds than the 2D model. However, the developing convective clouds of small areas at lower heights cannot be identified with the 3D model because they are covered by thick stratiform clouds. In addition, the 3D model can avoid the influence of the melting layer and better suggest convective clouds in the developmental stage.  相似文献   

农业种植规模与降水量变化对农用地下水开采量影响识别   总被引：1，自引：0，他引：1  

刘中培  于福荣  焦建伟 《地球科学进展》2012,27(2):240-245

以石家庄平原区作为研究区域,运用相关分析及回归分析阐明农用地下水开采量与降水量及小麦—玉米种植规模之间的关系。降水量与农用地下水开采量之间的相关系数较小,但作为农作物需水的重要水源,降水量通过影响农业地下水开采强度影响地下水开采总量。农业地下水开采强度在丰水年时明显减小,在枯水年时明显增大。小麦和玉米作为主要的耗水型作物,其种植面积与农用地下水开采量关系密切,随小麦—玉米种植面积的增加(减小),农用地下水开采量表现出明显的增加(减小)趋势。1981年之前,小麦—玉米种植面积每增加1×104 hm2,农用地下水开采量平均增加0.69×108 m3;1981年之后,小麦—玉米种植面积每增加1×104 hm2,农用地下水开采量增加0.23×108 m3。  相似文献   

明渠非恒定流流速分布及推移质运动研究进展          下载免费PDF全文

马爱兴  陆彦  陆永军  曹民雄 《水科学进展》2012,23(1):134-142

明渠非恒定流流速分布及非恒定流作用下推移质运动分别是水力学和泥沙运动力学研究中的重要问题之一。近几十年来,国内外许多学者在这些领域做过很多探索,取得了一定进展,也存在较多问题。在总结相关研究成果的基础上,简述了明渠非恒定流试验方法、流速分布、床面切应力、非恒定流输沙与水流运动不同步现象、产生原因、以及非恒定流推移质输沙公式等方面的成果,指出了现有研究中存在的不足,提出了需要进一步研究的关键问题:应用先进的量测仪器,研究非恒定流作用下非均匀沙运动输移规律。  相似文献   

土壤水分对土壤参数的敏感性及其参数优化方法研究   总被引：2，自引：0，他引：2  

张添  黄春林  沈焕锋 《地球科学进展》2012,27(6):678-685

利用2008年1月1日至2009年9月31日黑河流域阿柔冻融观测站的气象和土壤水分数据,采用基于方差的多参数敏感性分析方法研究通用陆面模型(Common Land Model,CoLM)模拟的土壤水分对土壤质地(砂土和黏土)的敏感性,进而采用SCE-UA参数优化算法分别优化土壤质地和土壤水力参数,分析不同优化策略对土壤水分模拟结果的影响。研究结果表明,浅层土壤水分对土壤质地较为敏感,敏感性系数达到了0.45以上,并且砂土含量对土壤水分的影响更为显著;利用SCE-UA算法优化土壤质地或土壤水力参数都可以有效地提高土壤水分的模拟精度,优化土壤水力参数易产生"异参同效"现象,而优化土壤质地能够使土壤水力参数的取值范围更加合理。  相似文献   

城市地铁深基坑开挖实测与数值模拟分析     

刘月涛  杨华伟 《岩土工程技术》2012,26(2):78-81

城市地铁施工中由于周边环境复杂,基坑开挖引起的土层扰动,可能会造成建筑物及地下管线破坏,甚至引起基坑失稳。以某地铁深基坑工程为背景,借助FLAC3D,建立了基坑开挖计算模型。现场实测与模型计算结果表明,计算值和实测值基本吻合,采用的计算模型可以近似模拟实际开挖过程。通过改变模型参数,研究了围护桩刚度、锚索倾角及锚索位置对围护体系受力和变形的影响,得出一些有益的结论,为保证城市深基坑开挖周边环境及围护结构安全,提供一定的参考。  相似文献