巯基棉富集-氢化物发生原子荧光法测定地质样品的总硒含量     

樊海峰  温汉捷  胡瑞忠  畅斌  凌宏文 《矿物学报》2008,28(2):181-186

地球化学标准参考物质和不同的地质样品均分别采用消解方式A(硝酸、高氯酸混合液)、B(硝酸、高氯酸、氢氟酸混合液)体系消解,样品预先用巯基棉(TCF)吸附装置分离富集,通过氢化物发生原子荧光光谱法(HG-AFS)测试.实验优化了Se(Ⅵ) 到 Se(Ⅳ)的还原效果、仪器条件、TCF吸附条件.两种消解体系所测得结果有很好的一致性,相关系数为0.9986.对于含硒量为0.04 μg/g样品,方法的相对标准偏差为10.2%.A、B体系标准加入法的回收率分别为96%～106%和99%～104%.  相似文献   

Correlation Analysis of the Ultrasonic Emission from Loaded Rock Samples – the Study of Interaction of Microcracking Nucleation Centres     

J. Vilhelm  V. Rudajev  T. Lokajíček  J. Veverka 《Rock Mechanics and Rock Engineering》2008,41(5):695-714

Summary.  The locations of fractures within loaded rock samples are distributed irregularly because of the presence of inhomogeneities in the rock sample, the existence of primary microcracks and non-uniformly distributed stress. In the case of brittle fracture, the positions of these fractures can be determined by locating the foci of ultrasonic events that occur during fracturing. In some cases, the foci cluster into clouds that are restricted spatially and are referred to as nucleation centres. The purpose of this research was to determine the mutual relationship between the various nucleation centres, by cross-correlating the time-series of ultrasonic events produced by microcracking in the individual, separate nucleation centres. An additional goal was to assess the effect of the existence of such nucleation centres on the autocorrelation parameters. This study showed that the separate nucleation centres did not appear to influence one another even during the final stages of fracturing. Until now, autocorrelation analysis of acoustic emission time sequences has been applied to evaluate the mutual influence of individual events that occur in the whole sample volume, regardless of their location. In a previous study, it was found that before the total fracturing of the sample, the autocorrelation parameters changed significantly due to the increase in mutual relationship between successive events. In this study the separated nucleation centres determined by locating the ultrasonic events were subjected to autocorrelation analysis. It was demonstrated that, in the case of critical loading of the sample, the mutual influence between the events of a given nucleation centre can be observed. The experiments have demonstrated that the autocorrelation has a precursory nature and have shown that there is a significant difference in the autocorrelation parameters calculated between the set of all recorded events, and the specific sub-set. These differences must be taken into account when applying statistical predictions, for example, in the study of rock bursts. Author’s address: Jan Vilhelm, Charles University in Prague, Albertov 6, 128 43 Prague, Czech Republic  相似文献   

思想决定成败——从信息系统的信息收集机制说起     

叶方涛 《中国勘察设计》2008,(1):45-47

做好信息收集机制,对企业运行数据进行有效加工,促进信息系统高效应用,协助智能决策。  相似文献   

基于统计分析的数据挖掘中数据处理综述   总被引：1，自引：0，他引：1  

陈科  张保明  王宇灵  谢明霞 《测绘科学》2008,(Z1)

数据是一切数据挖掘工作的前提。文章将基于统计分析的数据挖掘中的数据处理工作分为前期处理和后期处理两部分,对其过程和处理方法作了综合论述,并通过实例比较分析进一步证明了数据处理对于知识发现的必要性和重要性。  相似文献   

THE EFFECT OF SAMPLE OPTIMIZATION ON THE ENSEMBLE KALMAN FILTER IN FORECASTING TYPHOON RAMMASUN (2014)     

李霁杭  万齐林  高郁东  肖辉 《热带气象学报(英文版)》2018,24(4):433-447

In a limited number of ensembles, some samples do not adequately reflect the true atmospheric state and can in turn affect forecast performance. This study explored the feasibility of sample optimization using the ensemble Kalman filter (EnKF) for a simulation of the 2014 Super Typhoon Rammasun, which made landfall in southern China in July 2014. Under the premise of sufficient ensemble spread, keeping samples with a good fit to observations and eliminating those with poor fit can affect the performance of EnKF. In the sample optimization, states were selected based on the sample spatial correlation between the ensemble state and observations. The method discarded ensemble states that were less representative and, to maintain the overall ensemble size, generated new ensemble states by reproducing them from ensemble states with a good fit by adding random noise. Sample selection was performed based on radar echo data. Results showed that applying EnKF with optimized samples improved the estimated track, intensity, precipitation distribution, and inner-core structure of Typhoon Rammasun. Therefore, the authors proposed that distinguishing between samples with good and poor fits is vital for ensemble prediction, suggesting that sample optimization is necessary to the effective use of EnKF.  相似文献   

Zinc Isotopic Compositions of NIST SRM 683 and Whole‐Rock Reference Materials          下载免费PDF全文

Sha Chen  Yuchen Liu  Jingya Hu  Zhaofeng Zhang  Zhenhui Hou  Fang Huang  Huimin Yu 《Geostandards and Geoanalytical Research》2016,40(3):417-432

In this study the homogeneity of the zinc isotopic composition in the NIST SRM 683 reference material was examined by measuring the Zn isotopic signature in microdrilled sample powders from two metal nuggets. Zinc was purified using AG MP‐1M resin and then measured by MC‐ICP‐MS. Instrumental mass bias was corrected using the “sample‐standard bracketing” method and empirical external normalisation with Cu doping. After evaluating the potential effects of varying acid mass fractions and different matrices, high‐precision Zn isotope data were obtained with an intermediate measurement precision better than ± 0.05‰ (δ⁶⁶Zn, 2s) over a period of 5 months. The δ⁶⁶Zn_JMC‐Lyon mean values of eighty‐four and fourteen drilled powders from two nuggets were 0.11 ± 0.02‰ and 0.12 ± 0.02‰, respectively, indicating that NIST SRM 683 is a good isotopic reference material with homogeneous Zn isotopes. The Zn isotopic compositions of seventeen rock reference materials were also determined, and their δ⁶⁶Zn values were in agreement with most previously published data within 2s. The δ⁶⁶Zn values of most of the rock reference materials analysed were in the range 0.22–0.36‰, except for GSP‐2 (1.07 ± 0.06‰, n = 12), NOD‐A‐1 (0.96 ± 0.03‰, n = 6) and NOD‐P‐1 (0.78 ± 0.03‰, n = 6). These comprehensive data should serve as reference values for quality assurance and interlaboratory calibration exercises.  相似文献   

车载LiDAR场景中路灯的提取与识别     

张西童  刘会云  李永强  黄腾达  李有鹏 《测绘工程》2016,25(9):50-54

为解决车载LiDAR城市场景中路灯提取和识别问题,文中提出基于样本的路灯提取算法。先通过人机交互的方式提取路灯的样本参数;再依据数学形态学闭运算提取点云场景中疑似路灯的位置,根据样本参数确定疑似路灯范围并提取疑似路灯点云;然后进行路灯样本和疑似路灯点云的匹配;最后,通过建立路灯样本缓冲区实现路灯判断和提取。通过试验验证,算法不仅可以快速自动提取路灯点云,还能完成路灯单一种类的识别。  相似文献   

Spatially simplified scatterplots for large raster datasets     

Bin Li  Daniel A. Griffith  Brian Becker 《地球空间信息科学学报》2016,19(2):81-93

Abstract

Scatterplots are essential tools for data exploration. However, this tool poorly scales with data-size, with overplotting and excessive delay being the main problems. Generalization methods in the attribute domain focus on visual manipulations, but do not take into account the inherent nature of information redundancy in most geographic data. These methods may also result in alterations of statistical properties of data. Recent developments in spatial statistics, particularly the formulation of effective sample size and the fast approximation of the eigenvalues of a spatial weights matrix, make it possible to assess the information content of a georeferenced data-set, which can serve as the basis for resampling such data. Experiments with both simulated data and actual remotely sensed data show that an equivalent scatterplot consisting of point clouds and fitted lines can be produced from a small subset extracted from a parent georeferenced data-set through spatial resampling. The spatially simplified data subset also maintains key statistical properties as well as the geographic coverage of the original data.  相似文献   

浅谈我国某金红石矿采样设计     

卿得成 《国土资源导刊(湖南)》2016,(4):80-83

选矿试验采样设计是一项复杂而又重要的工作,确保试样的代表性是采样设计工作的关键。本文以我国某金红石矿为例,根据矿床地质特征和矿石的性质,综合考虑影响矿石代表性的各种因素,对其进行了采样设计,以确保能够采出满足试验要求、且具有带表性的试验样品。对类似项目具有一定的指导和借鉴意义。  相似文献   

电感耦合等离子体质谱法测定土壤重金属普查样品中铬铜镉铅的关键环节研究   总被引：10，自引：8，他引：2  

李自强  李小英  钟琦  苏文峰  诸堃 《岩矿测试》2016,35(1):37-41

土壤重金属普查样品的基质复杂、数量大、待测元素性质各异,现有土壤中重金属的电感耦合等离子体质谱法(ICP-MS)存在样品分解方式不适宜、上机测定参数需优化等问题。本文采用电热板-酸分解样品,研究了ICP-MS测定土壤中Cr、Cu、Cd、Pb四种主要重金属在分解和上机测定中的关键环节。结果表明采用"硝酸+盐酸+氢氟酸+50%硫酸"体系,样品分解完全且待测元素无损失,并使用工作曲线校准仪器可降低基体效应;优选质谱测定同位素和采用碰撞反应池或数学校正可减少质谱干扰;质谱积分驻留时间和重复次数对痕量元素Cd的精密度有较大影响,宜设为0.4 s和3次。本方法对Cr、Cu、Cd、Pb的检出限分别为1.74、0.89、0.015、0.08μg/g,为普查工作提供了一种可借鉴的分析手段。  相似文献