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271.
Binh Thai Pham Dieu Tien Bui Indra Prakash Long Hoang Nguyen M. B. Dholakia 《Environmental Earth Sciences》2017,76(10):371
Landslide susceptibility assessment using GIS has been done for part of Uttarakhand region of Himalaya (India) with the objective of comparing the predictive capability of three different machine learning methods, namely sequential minimal optimization-based support vector machines (SMOSVM), vote feature intervals (VFI), and logistic regression (LR) for spatial prediction of landslide occurrence. Out of these three methods, the SMOSVM and VFI are state-of-the-art methods for binary classification problems but have not been applied for landslide prediction, whereas the LR is known as a popular method for landslide susceptibility assessment. In the study, a total of 430 historical landslide polygons and 11 landslide affecting factors such as slope angle, slope aspect, elevation, curvature, lithology, soil, land cover, distance to roads, distance to rivers, distance to lineaments, and rainfall were selected for landslide analysis. For validation and comparison, statistical index-based methods and the receiver operating characteristic curve have been used. Analysis results show that all these models have good performance for landslide spatial prediction but the SMOSVM model has the highest predictive capability, followed by the VFI model, and the LR model, respectively. Thus, SMOSVM is a better model for landslide prediction and can be used for landslide susceptibility mapping of landslide-prone areas. 相似文献
272.
273.
北京城市休闲商务区的时空分布特征与成因 总被引:12,自引:1,他引:11
城市休闲商务区(Recreational Business District, RBD)作为城市重要的游憩空间,为外来游客和城市居民提供休闲消费的场所,逐渐受到学界和业界重视。目前大多数研究还停留在概念层面,在分类、空间结构、分布规律、分异成因等方面上还缺乏一定的实证和定量研究。结合前人研究经验,重新定义RBD,并依据城市RBD的特征和属性将其分为大型购物中心、休闲商业街、城市休闲区三类。选取1990年、2000年、2014年三个时间截面对北京各类城市RBD点进行统计,采用基尼系数、空间插值、核密度分析、地理探测器等方法,结合ArcGIS软件,对北京城市RBD的时空分布特征和成因进行分析,得出以下结论:① 时序上看,北京城市RBD的数量和规模不断增加,增速变快,不同类型的RBD出现不同幅度的空间扩张;② 北京城市RBD的空间集聚程度不断加强,不同类型的RBD,存在一定的增幅和增速差异;③ 北京城市RBD的整体空间结构呈“单核聚集—双核发展—网状扩散”的发展模式;④ 城市RBD多选址在交通便利、临近旅游景区、居民和游客密度较高、地价相对较高的地区。⑤ 游客密度对各类型的城市RBD规模均有较大影响;对于不同类型的城市RBD,各因素对其规模的影响也有所不同。 相似文献
274.
275.
Margarida Nunes Filipe Martinho Anaïs Vernisseau Philippe Marchand Bruno Le Bizec Henk W. van der Veer Henrique N. Cabral Fernando Ramos Miguel A. Pardal 《Marine pollution bulletin》2014
Contamination levels and profiles of 7 polychlorinated-p-dioxins, 10 polychlorinated furans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (dl-PCBs) were investigated in juvenile European flounder (Platichthys flesus) captured in different nursery areas in the northeastern Atlantic coast across its geographical distribution range. The toxic equivalent concentrations (WHO-TEQfish) were also determined in order to evaluate which P. flesus population was more exposed to dioxin-like toxicity. Juveniles caught in the Sørfjord (Norway) showed the lowest WHO-TEQfish concentration (0.052 pg WHO-TEQfish g−1 wet weight) whereas the highest value was observed in fish from the Wadden Sea (The Netherlands; 0.291 pg WHO-TEQfish g−1 ww), mainly due to the greater contribution of 2,3,7,8-tetrachlorodibenzo-p-dioxin, the most toxic congener. Nonetheless, when comparing the results with existent tissue residue-based toxicity benchmarks, no adverse effects resulting from PCDD/Fs and dl-PCBs are expected to occur in flounder from the studied systems. 相似文献
276.
Victoria A. Bendall Jonathan L. BarberAlexandra Papachlimitzou Thi BolamLee Warford Stuart J. HetheringtonJoana F. Silva Sophy R. McCullySara Losada Thomas MaesJim R. Ellis Robin J. Law 《Marine pollution bulletin》2014
The North-East Atlantic porbeagle (Lamna nasus) population has declined dramatically over the last few decades and is currently classified as ‘Critically Endangered’. As long-lived, apex predators, they may be vulnerable to bioaccumulation of contaminants. In this study organohalogen compounds and trace elements were analysed in 12 specimens caught as incidental bycatch in commercial gillnet fisheries in the Celtic Sea in 2011. Levels of organohalogen contaminants were low or undetectable (summed CB and BDE concentrations 0.04–0.85 mg kg−1 wet weight). A notably high Cd concentration (7.2 mg kg−1 wet weight) was observed in one mature male, whereas the range observed in the other samples was much lower (0.04–0.26 mg kg−1 wet weight). Hg and Pb concentrations were detected only in single animals, at 0.34 and 0.08 mg kg−1 wet weight, respectively. These contaminant levels were low in comparison to other published studies for shark species. 相似文献
277.
为了配合汶川地震科学深钻,弄清楚钻孔附近浅层的断层面结构,中国地震局地球物理研究所分别在四川省绵竹市天池乡和四川省绵阳市南坝镇布设15套南非矿山地震研究所(IMS)生产的矿山地震仪.分析矿山地震仪天然微震监测中仪器布设、数据采集和数据处理等方面遇到的问题,介绍与该仪器对应的数据的文件格式,并实现该数据与通用地震数据格式SAC二进制格式的转换. 相似文献
278.
LuanYun Hu YanLei Chen Yue Xu YuanYuan Zhao Le Yu Jie Wang Peng Gong 《中国科学:地球科学(英文版)》2014,57(10):2293-2304
Remote sensing based land cover mapping at large scale is time consuming when using either supervised or unsupervised classification approaches. This article used a fast clustering method—Clustering by Eigen Space Transformation(CBEST) to produce a land cover map for China. Firstly, 508 Landsat TM scenes were collected and processed. Then, TM images were clustered by combining CBEST and K-means in each pre-defined ecological zone(50 in total for China). Finally, the obtained clusters were visually interpreted as land cover types to complete a land cover map. Accuracy evaluation using 2159 test samples indicates an overall accuracy of 71.7% and a Kappa coefficient of 0.64. Comparisons with two global land cover products(i.e., Finer Resolution Observation and Monitoring of Global Land Cover(FROM-GLC) and GlobCover 2009) also indicate that our land cover result using CBEST is superior in both land cover area estimation and visual effect for different land cover types. 相似文献
279.
对煤矿长斜井盾构机(tunnel boring machine,TBM)施工的风险因素进行了识别,建立了二层次的风险评估指标体系,并确定了风险等级分类标准,利用熵权法确定风险指标的权向量,进而建立了基于集对分析法的煤矿长斜井TBM施工同异反评估模型。在此基础上利用偏联系数的理论确定了文中五元偏联系数的计算方法,根据改进的集对势理论给出风险趋势的预测方法。利用该模型对台格庙矿区煤矿长斜井(1#、2#实验井)TBM施工风险进行了评估与趋势预测。研究表明该模型与方法在煤矿长斜井TBM施工风险分析中是有效的、实用的,可为煤矿长斜井TBM施工风险分析与预测提供一种新的途径。 相似文献
280.
According to the present situation and problems of land use in Huanghua, this article determines the objectives of optimal allocation of land resources. As the basis of gray linear programming approach, we create gray linear programming model and set decision variables. By constructing the objective function and collection of constraint equations in which the main constraints is water resources, we obtain the program of optimal allocation of land resources under different constraints of water resources. The optimal result is analyzed to the present situation and planning of land use, to study feasibility of the program and the effectiveness in the decision of sustainable use of water -soil resources 相似文献