基于等价权抗差估计和线性规划的天线曲面拟合算法     

苏小文  李志静  黄浩 《测绘与空间地理信息》2016,(7):207-209

现有天线曲面拟合算法均基于最小二乘法,难以消除多个粗差对拟合结果的影响。本文基于等价权抗差估计思想,利用线性规划计算残差初值,再进行选权迭代计算。通过算例,证明本文方法能较好地探查多个粗差,且计算结果精度更高。  相似文献   

局部区域模型重力异常快速算法     

邢志斌  李姗姗  曲政豪  王伟  范昊鹏  贾鲁 《测绘科学技术学报》2016,(6):566-571

地球重力场位系数模型可以用于计算局部重力扰动场元。然而随着地球重力场模型阶次的提高、局域重力场计算范围的增大,其计算速度往往不能满足工程需求。针对这一问题,在对位系数模型泰勒级数展开的基础上提出了采用向量运算、混合编程的方法,同时对连带勒让德函数Belikov递推方法中与经纬度无关的量进行了预先计算,有效提高了计算速度。提出的方法对于利用超高阶次重力场模型快速解算大范围、高分辨率重力场元数据以及累加求和计算具有一定的参考与借鉴意义。  相似文献   

基于 DTW 距离的时序 NDVI 数据植被信息提取--以秦巴山区为例     

韩晓勇  韩玲  陈鲁皖 《测绘工程》2016,25(3):11-16

秦巴山区是我国重要的生态屏障,对该区的植被信息提取开展研究,可为区内生态服务功能及自然资源开发利用提供基础数据。通过加窗处理改进DTW距离相似性算法,结合临近度模糊分类方法对2005—2014年的MODIS NDVI时序数据进行植被信息提取。首先利用S-G滤波对MODIS NDVI时序数据进行重建;再利用2013年的采样数据构建各类植被的标准NDVI时序曲线,逐像元计算与标准NDVI时序曲线的加窗DTW距离,利用临近度模糊分类实现植被信息提取;最后验证提取精度。结果表明,算法具有较高的运行效率,可避免错误匹配,以较高的精度(总体精度83.8%,kappa系数0.77)实现长时间序列的植被信息提取。  相似文献   

改进支持向量机的高分遥感影像道路提取   总被引：2，自引：0，他引：2  

朱恩泽  宋伟东  戴激光 《测绘科学》2016,41(12):224-228

针对支持向量机受分类数的限制在高分辨率遥感影像中无法直接获取高精度道路网信息的问题,该文提出一种新的混合的基于支持向量机的方法:首先,利用模糊C均值聚类方法将输入的遥感影像分为3类,以减少支持向量机的错分现象;其次,运用支持向量机将不同类别的像素分为道路类和非道路类;最后,应用马尔科夫随机场对分类结果进行噪声去除,并采用形态学进行后处理,进而得到精确道路网信息。实验结果表明:该算法不仅能够从高分辨率遥感影像中提取出道路网,而且精度优于直接使用支持向量机算法以及对比算法。  相似文献   

Integrating cellular automata,artificial neural network,and fuzzy set theory to simulate threatened orchards: application to Maragheh,Iran   总被引：1，自引：0，他引：1  

Mehdi Azari  Amin Tayyebi  Marco Helbich  Mohsen Ahadnejad Reveshty 《地理信息系统科学与遥感》2016,53(2):183-205

Urbanization processes challenge the growth of orchards in many cities in Iran. In Maragheh, orchards are crucial ecological, economical, and tourist sources. To explore orchards threatened by urban expansion, this study first aims to develop a new model by coupling cellular automata (CA) and artificial neural network with fuzzy set theory (CA–ANN–Fuzzy). While fuzzy set theory captures the uncertainty associated with transition rules, the ANN considers spatial and temporal nonlinearities of the driving forces underlying the urban growth processes. Second, the CA–ANN–Fuzzy model is compared with two existing approaches, namely a basic CA and a CA coupled with an ANN (CA–ANN). Third, we quantify the amount of orchard loss during the last three decades as well as for the upcoming years up to 2025. Results show that CA–ANN–Fuzzy with 83% kappa coefficient performs significantly better than conventional CA (with 51% kappa coefficient) and CA–ANN (with 79% kappa coefficient) models in simulating orchard loss. The historical data shows a considerable loss of 26% during the last three decades, while the CA–ANN–Fuzzy simulation reveals a considerable future loss of 7% of Maragheh’s orchards in 2025 due to urbanization. These areas require special attention and must be protected by the local government and decision-makers.  相似文献   

耦合长期预报的跨流域引水受水水库调度模型          下载免费PDF全文

卢迪  周如瑞  周惠成  彭勇 《水科学进展》2016,27(3):458-466

为提高跨流域引水工程受水水库引水有效性,研究了耦合长期径流预报信息的跨流域引水受水水库调度模型。首先选取汛期径流预报信息,采用径流预报概率修正先验概率来描述径流的不确定性,建立了贝叶斯随机动态规划模型(BSDP-LTF)。然后将模型应用于碧流河水库,并与仅考虑径流相关的随机动态规划模型(SDP-I)、仅考虑长期预报信息的随机动态规划模型(SDP-LTF)进行比较。比较结果得出在供水保证率基本一致且不增加调度风险的情况下,BSDP-LTF模型相比SDP-I、SDP-LTF模型,可分别减少引水8.2%、4.1%。表明贝叶斯随机动态规划模型BSDP-LTF有效改进了径流描述,提高了跨流域引水的有效性。  相似文献   

Possibilities of land use change analysis in a mountainous rural area: a methodological approach     

Szilárd Szabó  László Bertalan  Ágnes Kerekes  Tibor J. Novák 《International journal of geographical information science》2016,30(4):708-726

Decreasing population density is a current trend in the European Union, and causes a lower environmental impact on the landscape. However, besides the desirable effect on the regeneration processes of semi-natural forest ecosystems, the lack of traditional management techniques can also lead to detrimental ecological processes. In this study we investigated the land use pattern changes in a micro-region (in North-Eastern Hungary) between 1952 and 2005, based on vectorised land use data from archive aerial photos. We also evaluated the methodology of comparisons using GIS methods, fuzzy sets and landscape metrics. We found that both GIS methods and statistical analysis of landscape metrics resulted in more or less the same findings. Differences were not as relevant as was expected considering the general tendencies of the past 60 years in Hungary. The change in the annual rate of forest recovery was 0.12%; settlements extended their area by an annual rate of 3.04%, while grasslands and arable lands had a net loss in their area within the studied period (0.60% and 0.89%, respectively). The kappa index showed a smaller similarity (~60%) between these dates but the fuzzy kappa and the aggregation index, taking into account both spatial and thematic errors, gave a more reliable result (~70–80% similarity). Landscape metrics on patch and class level ensured the possibility of a detailed analysis. We arrived at a similar outcome but were able to verify all the calculations through statistical tests. With this approach we were able to reveal significant (p < 0.05) changes; however, effect sizes did not show large magnitudes. Comparing the methods of revealing landscape change, the approach of landscape metrics was the most effective approach, as it was independent of spatial errors and ensuring a multiple way of interpretation.  相似文献   

Parallel cartographic modeling: a methodology for parallelizing spatial data processing     

Eric Shook  Michael E. Hodgson  Shaowen Wang  Babak Behzad  Kiumars Soltani  April Hiscox 《International journal of geographical information science》2016,30(12):2355-2376

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Evaluation of effectiveness of three fuzzy systems and three texture extraction methods for building damage detection from post-event LiDAR data     

Milad Janalipour 《International Journal of Digital Earth》2018,11(12):1241-1268

Building damage maps after disasters can help us to better manage the rescue operations. Researchers have used Light Detection and Ranging (LiDAR) data for extracting the building damage maps. For producing building damage maps from LiDAR data in a rapid manner, it is necessary to understand the effectiveness of features and classifiers. However, there is no comprehensive study on the performance of features and classifiers in identifying damaged areas. In this study, the effectiveness of three texture extraction methods and three fuzzy systems for producing the building damage maps was investigated. In the proposed method, at first, a pre-processing stage was utilized to apply essential processes on post-event LiDAR data. Second, textural features were extracted from the pre-processed LiDAR data. Third, fuzzy inference systems were generated to make a relation between the extracted textural features of buildings and their damage extents. The proposed method was tested across three areas over the 2010 Haiti earthquake. Three building damage maps with overall accuracies of 75.0%, 78.1% and 61.4% were achieved. Based on outcomes, the fuzzy inference systems were stronger than random forest, bagging, boosting and support vector machine classifiers for detecting damaged buildings.  相似文献   

金沙江白格滑坡残留体稳定性分析与防治对策     

朱德明  李鹏岳  胡孝洪  吴新明 《现代地质》2021,35(1):56-63

金沙江白格滑坡在经历了2018年10月和11月的2次滑动堵江后,在其后缘仍存在K1、K2和K3等3处规模较大的残留崩滑体,并有再次失稳堵江的可能。目前关于残留体稳定性的研究还存在较大争议,多从影响因素及成因机制等方面进行定性分析,其结果依赖于评价者的经验,差异较大。在野外调查的基础上,针对白格滑坡所在区工程地质条件及其残留体变形特征,选取坡高、坡度、坡面形态、临空面、地下水出露、裂缝发育和变形等7个因素作为评价因子,基于模糊综合评判模型,运用层次分析法对白格滑坡残留体进行分区稳定性评价,并提出相应的防治对策。评价结果表明:K1与K2残留体稳定性较差;K3残留体基本稳定,与实际调查状况较吻合。研究结果可为同类型滑坡的评价与防治提供参考。  相似文献