利用GPS连续观测资料进行强震危险性预测的探讨   总被引：1，自引：0，他引：1  

杨国华  张风霜  武艳强  韩月萍  沈午春  杨博 《地震》2008,28(1):33-39

中国地壳运动观测网络基准站自1999运行以来已经积累了8年多的观测资料,目前针对地震预测、观测对象和数据处理方法,广义地提出了"点、线、面"的分析方法。实际应用表明,利用"线"的分析方法可能是比较好的方法,它最大的优点是在恰当的空间范围内不但可降低噪声,而且可突出异态信息。在目前较低测控能力的基础上,可通过全空间扫描与现象分析发现:①距昆仑山口西地震震中最近的德令哈观测站相对于拉萨观测站在震前较早的时间,其EW向就出现了缓慢变化,乃至闭锁(或无差异变化),直至地震发生为止,持续时间超过2年,闭锁数值10 mm以上,震后恢复正常;②云南地区数次强震震前下关观测站相对于泸州观测站EW向出现了闭锁或低于正常的变化,2003年强震之后恢复正常;最近的普洱强震自2006年初EW与SN向均出现了相对闭锁,两个方向的数值分别接近和达到10 mm;此外,每阶段异常的持续时间均超过1年;③塔什—乌什间EW向在新疆巴楚地震前出现了闭锁性活动,时间2年以上,数值约10 mm,震后恢复正常;目前SN向有相对闭锁迹象,并正在趋于明朗;④鼎新—西宁间EW方向有相对闭锁的迹象,但时间尚短;⑤通过寻找相对"闭锁"区段有可能成为判定强震危险性存在与否的主要方法。由此推测,若普洱6.4级地震后闭锁不解除,川滇菱形块体的西边界构造带及周围地区仍是近期强震最有可能发生的地区,其次是新疆的西天山地区,目前青藏高原东北缘尚不明朗。  相似文献   

The spatial ecology of deer–vehicle collisions     

Rusty A. Gonser  Ryan R. Jensen  Samuel E. Wolf 《Applied geography (Sevenoaks, England)》2009,29(4):527-532

Deer–vehicle collisions (DVCs) are a constant problem in North America that cost millions of dollars of damage and loss of human life. This study investigated the spatial relationship of DVCs for a county in western Indiana using nearest neighbor analysis, chi-square test of independence, and a landscape metric: the percentage of like adjacencies. The study was able to show that DVCs are not randomly located, and that habitat type and structure may play an important role in the location of DVCs.  相似文献   

A positive definite continuous FEM model for advection     

Pablo Ortiz 《Advances in water resources》2009

This work introduces a continuous and sign-preserving finite element model (FEM) for advection problems. The model is formulated by integrating flux corrected transport technique (FCT) with the characteristic based (CB) FEM. Low order solution for the FCT has the form of element contribution and derives from an upwind monotone scheme with the minimum necessary diffusion for positivity. Selected numerical experiments illustrate the efficacy of the method by comparing results with some successful models, by demonstrating an approximate conservation of the accuracy of original CB algorithm once the complete procedure is operating, and by testing the model for severe time dependent advective flows.  相似文献   

Delineation of geological facies from poorly differentiated data     

Brendt Wohlberg  Daniel M. Tartakovsky 《Advances in water resources》2009

The ability to delineate geologic facies and to estimate their properties from sparse data is essential for modeling physical and biochemical processes occurring in the subsurface. If such data are poorly differentiated, this challenging task is complicated further by the absence of a clear distinction between different hydrofacies at locations where data are   available. We consider three alternative approaches for analysis of poorly differentiated data: a k$k$-means clustering algorithm, an expectation–maximization algorithm, and a minimum-variance algorithm. Two distinct synthetically generated geological settings are used to analyze the ability of these algorithms to assign accurately the membership of such data in a given geologic facies. On average, the minimum-variance algorithm provides a more robust performance than its two counterparts, and when combined with a nearest neighbor algorithm, it also yields the most accurate reconstruction of the boundaries between the facies.  相似文献   

Calanus finmarchicus in the North Atlantic: the year of Calanus in the context of interdecadal change   总被引：1，自引：0，他引：1  

Planque  B.; Batten  S. D. 《ICES Journal of Marine Science》2000,57(6):1528-1535

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Sinkhole hazard assessment in Minnesota using a decision tree model     

Yongli Gao  E. Calvin AlexanderJr 《Environmental Geology》2008,54(5):945-956

An understanding of what influences sinkhole formation and the ability to accurately predict sinkhole hazards is critical to environmental management efforts in the karst lands of southeastern Minnesota. Based on the distribution of distances to the nearest sinkhole, sinkhole density, bedrock geology and depth to bedrock in southeastern Minnesota and northwestern Iowa, a decision tree model has been developed to construct maps of sinkhole probability in Minnesota. The decision tree model was converted as cartographic models and implemented in ArcGIS to create a preliminary sinkhole probability map in Goodhue, Wabasha, Olmsted, Fillmore, and Mower Counties. This model quantifies bedrock geology, depth to bedrock, sinkhole density, and neighborhood effects in southeastern Minnesota but excludes potential controlling factors such as structural control, topographic settings, human activities and land-use. The sinkhole probability map needs to be verified and updated as more sinkholes are mapped and more information about sinkhole formation is obtained.  相似文献   

如何利用化石植物定量研究古海拔？     

孙启高 《地质论评》2008,54(2):145-154

古海拔问题是当前古植物学与古环境研究领域中的难点之一,属于化石植物生物学与地球科学和环境科学相互交叉、相互渗透的前沿性研究。定量研究古海拔的变化对阐述诸如青藏高原抬升历史等重大科学问题具有十分重要的意义。应用生物学的思想和方法,利用化石植物研究地质历史时期古海拔的变化是当前研究的一个热点。化石植物既是研究地质历史时期植被演替的直接证据,又是研究古海拔变化的珍贵材料。本文简述了利用化石植物定量研究古海拔的3类主要方法,即最近亲缘种分析、共存因子分析和叶相分析的基本原理和实际应用,侧重分析中国地区（如西藏南部南木林盆地）古海拔的研究进展和存在问题,并结合近年来的研究实践展望了将来的工作。  相似文献   

核密度法的南京苏果超市分布热点探测     

吴嘉逸  席唱白  苑振宇  芮一康  王结臣 《测绘科学》2017,42(11)

针对超市经营者进行选址优化和空间配置问题,该文以南京市主城区内苏果超市为例,利用平面核密度方法,对城市内零售超市的空间结构与分布模式进行分析,系统地研究不同类型超市的空间分布特征并进行热点区域的探测。研究表明,热点区域的探测结果符合商业网点分布的一般规律,南京主城区内不同类型苏果超市的空间分布表现出较大的空间区域分异:购物广场的热点分布于中心城区外围的次一级中心,社区店和标准超市的热点分布于居住区,便利店的热点大多分布于人口密集区域。  相似文献   

灰度直方图与K-最近邻的影像分割算法     

杨帆  郭建华  谭海  王竞雪 《测绘科学》2017,42(3)

针对灰度直方图在影像分类时需要考虑阈值和K-最近邻分类算法分类效率低等问题,提出了一种基于灰度直方图与KNN相结合的影像分割算法:首先对待分割的影像进行灰度直方图统计;其次利用灰度直方图对影像进行硬阈值的划分,得到已知类别样本和未标记样本;然后选择一定数量已知类别的样本对KNN分类器进行训练;最后利用KNN分类器对未标记样本进行类别划分,得到最终分割图像。实验结果表明,该算法结合了灰度直方图高效性和KNN高精度的优势,避免了直方图分割最佳阈值的选取;与传统的KNN算法相比,本文算法大大提高了分类效率,且精度相当,满足实际生产应用的需求。  相似文献   

Auswirkung von Schwermetallgemischen auf die biologische Behandlung naphthalinsulfonsäurehaltiger Abwässer     

H. Pack  D. C. Hempel 《洁净——土壤、空气、水》1997,25(6):306-310

Effect of Mixtures of Heavy Metals on the Biological Treatment of Sewages Containing Naphthalenesulfonic Acid Biological wastewater treatment processes can be destabilized considerably by heavy metals. In this investigation, the effect of loadings of heavy metals on the degradation of naphthalene-2-sulfonic acid (2NS) by immobilized bacteria in continuously operated airlift-loop reactors was studied. Shock loadings with mixtures of cadmium and nickel, or cadmium and zinc, respectively, resulted in increases in inhibition compared to those observed with the single metals. In contrast, the 2NS-degradation was less inhibited by shock loadings with mixtures of nickel and zinc than by the single metal ions. Repeated shock loadings up to 100 mg L^?1 nickel and 1000 mg L^?1 zinc effected an adaptation of the microorganisms. Continuous loadings with up to 10 mg L^?1 cadmium and nickel each, or with 50 mg L^?1 nickel and 210 mg L^?1 zinc, respectively, did not inhibit the degradation of 2NS. The permanent loadings led to an adaptation of the bacteria with an increased biosynthesis of proteins from 0.2 to 0.5 g g^?1 cell dry weight. However, if the immobilized cells were incubated with mixtures of cadmium and nickel, the specific polysaccharide content decreased to less than 0.2 g g^?1 cell dry weight, resulting in a detachment of the biofilms.  相似文献