分布式增量机制下的交通流大数据聚类分析

时空聚类分析是对时空大数据进行利用的一种有效手段。本文提出了一种分布式增量大数据聚类分析方法,利用分布增量机制不但可以减少重复计算和迁移拷贝次数,而且可以持续对聚类结果进行修正,能够在保持聚类准确性的条件下提升整体运算效率。而聚类算法本身通过数据聚集趋势预分析、聚类算法和结果评价3个步骤,构建了一体化时空邻域,在时间和空间维度保证了聚类结果的准确性。经过试验证明该方法可以实现时空大数据的快速高效信息挖掘。     

自然灾害调查数据的多尺度异常检测方法研究及应用

大范围自然灾害调查,涉及区域环境差异大,数据获取方式多样,参与人员多,各级汇总成果中存在一些异常调查单元,需要人工判读其合理性,但单纯依靠人工从海量数据中有效识别异常是不现实的。本文设计了一种自然灾害调查数据的多尺度异常检测方法,综合运用离群检测方法和空间数据挖掘算法,分别进行异常值和异常空间分布模式检测,能够从海量调查数据中快速提取各级尺度的异常值和异常调查单元,支撑人工判读工作。将该方法应用于全国山洪灾害调查评价汇总数据的审核中,以全国历史山洪灾害点和防治区乡镇面积审核为例,分别快速提取了县乡两级区划中的山洪灾害点密度异常单元和面积值异常的乡镇单元,通过对检测结果进行分析,发现是填报口径不一致、单位错误、记录重复等原因造成的。最后分析了该方法在大范围自然灾害调查中的适用条件和方法。     

Selenium and other trace elements in phosphate rock of Bayovar–Sechura (Peru)

Selenium is an essential trace element in regard to human and other animals' health, but it presents a narrow range of dietary deficiency and toxic excess. Some phosphate rocks are rich in selenium. Furthermore it is necessary to control selenium's and other trace elements’ compositions in the phosphate rocks, because phosphorite ores of different geographical sites are varied, and even ores from the same outcrop can vary substantially in trace element levels.     

支持向量机在地球化学勘查中的应用

将K均值聚类和v -SVM结合, 推出一种改进的分类方法。该方法根据指标的相关性, 构建了具有强分辨能力的分类模型, 并将模型应用于内蒙某地勘查地球化学研究, 查明了所研究元素之间的相似性, 建立了v - SVM分类机, 实现了组合异常的圈定。     

Multivariate forecast of winter monsoon rainfall in India using SST anomaly as a predictor: Neurocomputing and statistical approaches

In this article, the complexities in the relationship between rainfall and sea surface temperature (SST) anomalies during the winter monsoon over India were evaluated statistically using scatter plot matrices and autocorrelation functions. Linear, as well as polynomial trend equations were obtained, and it was observed that the coefficient of determination for the linear trend was very low and it remained low even when polynomial trend of degree six was used. An exponential regression equation and an artificial neural network with extensive variable selection were generated to forecast the average winter monsoon rainfall of a given year using the rainfall amounts and the SST anomalies in the winter monsoon months of the previous year as predictors. The regression coefficients for the multiple exponential regression equation were generated using Levenberg-Marquardt algorithm. The artificial neural network was generated in the form of a multilayer perceptron with sigmoid non-linearity and genetic-algorithm based variable selection. Both of the predictive models were judged statistically using the Willmott's index, percentage error of prediction, and prediction yields. The statistical assessment revealed the potential of artificial neural network over exponential regression.     

应用于遥感图像分割的原型提取谱聚类集成算法

针对遥感图像数据量大、类别归属复杂的特点,提出了一种用于遥感图像分割的原型提取谱聚类算法。该算法首先采用广义模糊c-均值聚类算法对遥感图像进行过分割,将得到的聚类中心作为每个分割区域的代表点;然后,通过构造代表点之间的相似性矩阵,利用谱图划分方法对代表点进行聚类;最后,根据代表点的聚类结果对图像像素点进行重新归类来获得遥感图像的最终分割结果。此算法涉及到3个参数,为了克服算法对于参数的敏感性和内在的随机性,进一步引入集成策略,给出了原型提取谱聚类的集成算法。     

基于EM及熵值理论的区域经济与影响因素研究

基于EM算法的聚类方法属于软聚类范畴,在应用中具有较高的灵活性,而熵值理论可以较好地反映出分子对系统凝聚状态的影响度。以河南省为例应用EM聚类方法分析了各地市的经济发展水平,运用熵值理论对影响经济发展的各因素进行了评价,并计算得出各因素的影响度,以此探讨河南省各地市经济发展不平衡的特点和原因,并为经济的全面协调发展提供了对策和思路。     

Fractal Dimension of the 1999 Chamoli Earthquake from Aftershock Studies in Garhwal Himalaya

The Aftershock sequence of Chamoli earthquake (M _w 6.4) of 29 March 1999 is analyzed to study the fractal structure in space, time and magnitude distribution. The b value is found to be 0.63 less than which is usually observed worldwide and in the Himalayas. This indicates that the numbers of smaller earthquakes are relatively less than the larger ones. The spatial correlation is 1.64, indicating that events are approaching a two-dimensional region meaning that the aftershocks are uniformly distributed along the trend of the aftershock zone. Temporal correlation is 0.86 for aftershocks of M 1, indicating a nearly continuous aftershock activity. However, it is 0.5 for aftershocks of M 1.75, indicating a non continuous aftershock activity. From the assessment of slip on different faults it is inferred that 70% displacement is accommodated on the primary fault and the remainder on secondary faults.     

GIS-based landslide susceptibility mapping for a problematic segment of the natural gas pipeline,Hendek (Turkey)

A segment of natural gas pipeline was damaged due to landsliding near Hendek. Re-routing of the pipeline is planned, but it requires the preparation of a landslide susceptibility map. In this study, the statistical index (Wi) and weighting factor (Wf) methods have been used with GIS to prepare a landslide susceptibility map of the problematic segment of the pipeline. For this purpose, thematic layers including landslide inventory, lithology, slope, aspect, elevation, land use/land cover, distance to stream, and drainage density were used. In the study area, landslides occur in the unconsolidated to semi-consolidated clayey unit and regolith. The Wf method gives better results than the Wi method. Lithology is found to be the most important aspect in the study area. Based on the findings obtained in this study, the unconsolidated to semi-consolidated clayey unit and alluvium should be avoided during re-routing. Agricultural activities should not be allowed in the close vicinity of the pipeline.     

Global multiresolution models of surface wave propagation: comparing equivalently regularized Born and ray theoretical solutions

I invert a large set of teleseismic phase-anomaly observations, to derive tomographic maps of fundamental-mode surface wave phase velocity, first via ray theory, then accounting for finite-frequency effects through scattering theory, in the far-field approximation and neglecting mode coupling. I make use of a multiple-resolution pixel parametrization which, in the assumption of sufficient data coverage, should be adequate to represent strongly oscillatory Fréchet kernels. The parametrization is finer over North America, a region particularly well covered by the data. For each surface-wave mode where phase-anomaly observations are available, I derive a wide spectrum of plausible, differently damped solutions; I then conduct a trade-off analysis, and select as optimal solution model the one associated with the point of maximum curvature on the trade-off curve. I repeat this exercise in both theoretical frameworks, to find that selected scattering and ray theoretical phase-velocity maps are coincident in pattern, and differ only slightly in amplitude.