Efficiency of regression techniques for ore valuation at Kolar Gold Fields, India     

B. K. Verma 《Mathematical Geology》1972,4(1):25-34

The Kolar Gold Fields are some of the best known gold deposits in India. An example of ore valuation utilizing 49 ore blocks of the Oriental lode of the West Reefs, explored and developed in the Nundydroog mines, is given. In this reef system, there are large ore reserves of sulfidebearing quartz reefs, and the gold distribution is erratic both along strike and downdip. Ore valuation at present is based on the arithmetic mean of samples taken at peripheral positions of the blocks. Samples taken from internal portions of the blocks give a totally different picture of the value. To correct this discrepancy, normal regression and lognormal regression of internal block and total block values, over peripheral block values have been used to evaluate the deposits. The valuation efficiency criterion shows the logarithmic variance for distribution of ratios of unregressed and regressed block values with the corresponding arithmetic mean of internal stope values as observed inside the blocks. The studies have shown that the logarithmic variance is minimum if the logarithmic regression is used, thereby indicating maximum efficiency. Further, the undervaluation and overvaluation of low- and high-grade blocks is less for the logarithmic example. With help of the logarithmic regression equation an effective pay limit of 177.8 in.-dwt has been found for selective mining, for peripheral block values corresponding to the official pay limit of 240 in.-dwt.NGRI contribution number 71-281.  相似文献   

Geostatistical investigations of gabbro occurrences near Savantvadi, Ratnagiri district, India     

V. C. Chavadi  N. W. Gokhale  S. R. Kulkarni 《Mathematical Geology》1972,4(2):147-153

This paper embodies petrographical and statistical investigations of three gabbro occurrences. The Mangaon and Kunkeri gabbros are similar in petrography and petrochemistry, whereas they are completely different from the Vajrat gabbro. Application of recently developed statistical tests help in classifying these gabbros by using three oxides, CaO, FeO, and K₂O.This study shows that the evolution of the Mangaon and Kunkeri gabbros probably proceeded along different lines as compared to the Vajrat gabbro.  相似文献   

我国中东部雷暴活动特征分析     

王婷波  周康辉  郑永光 《气象》2020,46(2):189-199

基于2010—2014年国家闪电监测网的云-地闪电定位数据,利用雷暴识别与追踪算法获得了505 257个雷暴系统,进而统计分析了我国中东部地区的雷暴发生发展特征。考虑地形和气候差异,将我国中东部划分为东北、华北、华中与华东、西南、华南五个区域,对比了上述区域的雷暴中地闪活动持续时间、移动距离、移动速度等特征,并进一步对雷暴发生的环境物理量特征进行了统计分析,最后讨论了雷暴发生与地形的相关关系。结果显示:雷暴具有局地性强、快速生消的特性,超过70%的雷暴移动速度低于60 km·h~(-1),超过80%的雷暴持续时间低于2 h,超过90%的雷暴移动距离低于60 km;东北地区雷暴移动速度相对更快,西南地区移速较慢且雷暴移动距离更短。华中与华东、华南地区雷暴发生的整层可降水量与对流有效位能值最高,西南次之,东北与华北地区最低,而0～6 km垂直风切变则反之;广东、海南等地为雷暴发生最活跃区域,江南、西南地区东部、华南地区西部、华北地区太行山一带等地为雷暴发生较为活跃的地区;雷暴发生与地形密切相关,四川盆地西麓与珠江三角洲地区明显呈现出随地形抬升而导致雷暴触发的情况。  相似文献   

线性矩法与常规矩法对太湖流域降雨频率分析的比较研究   总被引：1，自引：1，他引：0  

梁玉音  刘曙光  钟桂辉  周正正  胡艳 《水文》2013,33(4):16-21

介绍了线性矩法的基本理论,并与常规矩法进行了初步的比较与分析,说明了其理论上的优越性;以太湖流域的雨量资料为例,选取4个站点分别应用线性矩法和常规矩法估计其不同重现期下年极值降雨频率设计值;最后,利用Monte Carlo方法对太湖流域内96个站点数据进行模拟,比较线性矩法和常规矩法所估计的统计参数。结果表明:线性矩法估计的参数在精确性、不偏性及稳健性方面较常规矩法更优。  相似文献   

浅议如何进行地理国情统计分析     

董菲 《东北测绘》2014,(6):186-187

地理国情基本统计是利用地理国情普查成果数据中的地表覆盖数据、国情要素数据、DEM数据进行综合统计分析。本文简单论述了地理国情统计分析的作业流程以及具体的操作方法。  相似文献   

《测绘科学》在中国知网的文献计量分析     

罗玲  王文福 《测绘科学》2013,38(4):209-212

本文运用网络计量学方法,利用CNKI中的《中国引文数据库》,以《测绘科学》2007～2011年论文为统计源,对该刊的一些重要评价指标进行了统计分析,揭示了《测绘科学》的学术水平和办刊质量以及在我国测绘科技期刊领域中的地位和学术影响力。  相似文献   

A study-based ranking of LiDAR data visualization schemes aided by georectified aerial images     

Suddhasheel Ghosh  Bharat Lohani  Neeraj Misra 《制图学和地理信息科学》2013,40(2):138-150

Light Detection and Ranging (LiDAR) collects dense 3D topographic information in the form of points. LiDAR data can be displayed either through direct rendering of the point cloud or by generalizing features extracted through classification or segmentation. We are working in the domain of visualizing LiDAR data sets and have developed certain pipelines for visualization. These pipelines have been presented elsewhere. We present a technique for the evaluation of visualization schemes for LiDAR data, by conducting a visualization experience survey for 13 pre-processing and visualization schemes where 60 participants rated these schemes on a 10 point scale on a questionnaire. The paper establishes a ranking for the different visualization schemes described herein. Finally, this paper establishes that our heuristic-based algorithm (presented elsewhere) performs almost equal to a classification-based visualization pipeline made using professional software. We believe that the presented technique can be used to assess other geospatial visualization schemes.  相似文献   

Morphometric Comparisons Between Rogen Terrain and Hummocky Terrain     

《自然地理学》2013,34(4):319-336

Visual interpretation of aerial photography suggests that certain geomorphological similarities exist between the hummocky terrain of central Alberta, Canada, and the Rogen terrain of Nunavut, Canada. This study statistically compares the two landform types based on measures of depression shapes and ridge orientations. Comparison of depression shapes indicates that two of three sample areas chosen from the hummocky terrain study area are statistically similar to those of the Rogen terrain study area. Analysis of ridge orientations indicates the ridge crests from two of three hummocky terrain sample areas, and ridge crests from within the Rogen terrain study site all exhibit a preferred trend. Variability in the process of formation may explain why only particular areas throughout the hummocky terrain exhibit patterns similar to the Rogen terrain and others do not. Statistical similarities in two-dimensional form between the hummocky terrain of central Alberta and the Rogen terrain of the Northwest Territories however, suggest that these landforms may have a common or similar origin.  相似文献   

Local entropy map: a nonparametric approach to detecting spatially varying multivariate relationships     

Diansheng Guo 《International journal of geographical information science》2013,27(9):1367-1389

The relationship between two or more variables may change over the geographic space. The change can be in parameter values (e.g., regression coefficients) or even in relation forms (e.g., linear, quadratic, or exponential). Existing local spatial analysis methods often assume a relationship form (e.g., a linear regression model) for all regions and focus only on the change in parameter values. Therefore, they may not be able to discover local relationships of different forms simultaneously. This research proposes a nonparametric approach, a local entropy map, which does not assume a prior relationship form and can detect the existence of multivariate relationships regardless of their forms. The local entropy map calculates an approximation of the Rényi entropy for the multivariate data in each local region (in the geographic space). Each local entropy value is then converted to a p-value by comparing to a distribution of permutation entropy values for the same region. All p-values (one for each local region) are processed by several statistical tests to control the multiple-testing problem. Finally, the testing results are mapped and allow analysts to locate and interactively examine significant local relationships. The method is evaluated with a series of synthetic data sets and a real data set.  相似文献   

Role of landscape parameters in riverine run-off,and sediment and organic matter yield on Disko Island,West Greenland     

Morten Rasch  Niels Nielsen  Christian Christiansen  Thomas Balstrøm  Robert Gilbert  Joseph Desloges 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):1-11

Measurements of discharge and suspended sediment and organic matter yield from nine different drainage basins on the island Disko in central West Greenland were carried out in the period 19–30 July 1997. A series of landscape properties (glacier cover, altitude, slope, aspect and vegetation cover) were measured for each drainage basin from a digital elevation model and a satellite image. Principal Component Analysis and regression statistics have been used to examine which landscape parameters dominate the measured discharges and yields. It is concluded that differences in suspended sediment and organic matter yield between the drainage basins can be explained by the measured morphometric properties while differences in water run-off can not. Glacier cover percentage and percent area above 800 m a.s.l. were the most important parameters influencing suspended sediment and organic matter yield in the drainage basins on Disko during the study period.  相似文献