ARTIFICIAL NEURAL NETWORK CORRECTION OF ROUGH ERRORS OF OBSERVATIONS*

In the context of tower measured radiation datasets.following the correction principle meeting a diagnostic equation in data quality control and in terms of a technique for model construction on data and ANN (artificial neural network) retrieval for BP correction of radiation measurements with rough errors available,a BP model is presented.Evidence suggests that the developed model works well and is superior to a convenient multivariate linear regression model,indicating its wide applications.     

A bilinear approximation of the surface relief in terrain correction computations

A new method is presented for the computation of the gravitational attraction of topographic masses when their height information is given on a regular grid. It is shown that the representation of the terrain relief by means of a bilinear surface not only offers a serious alternative to the polyhedra modeling, but also approaches even more smoothly the continuous reality. Inserting a bilinear approximation into the known scheme of deriving closed analytical expressions for the potential and its first-order derivatives for an arbitrarily shaped polyhedron leads to a one-dimensional integration with – apparently – no analytical solution. However, due to the high degree of smoothness of the integrand function, the numerical computation of this integral is very efficient. Numerical tests using synthetic data and a densely sampled digital terrain model in the Bavarian Alps prove that the new method is comparable to or even faster than a terrain modeling using polyhedra.     

GPS水汽遥感中的大气干延迟局地订正模型研究

在GPS遥感水汽过程中,大气干延迟模型的精度直接影响水汽遥感的精度。根据广东清远站1995～2001年的气象探空资料,计算了GPS水汽测量中的实际大气干延迟。在此资料基础上,利用地面气象要素建立了大气干延迟的年和分月局地订正模型。分析结果表明,年模型的精度优于目前广泛使用的普适模型;月模型与年模型相比,效果不是很明显,建立局地分月订正模型意义不大;在对高度角的敏感程度上,局地模型略大些;当高度角小于75时,大气干延迟弯曲路径与直线路径之差ΔS随天顶角增大而迅速增大。     

Correcting method of eddy covariance fluxes over non-flat surfaces and its application in ChinaFLUX

Although Eddy Covariance (EC) technique is one of the best methods for estimating the energy and mass exchanges between underlying surface and atmosphere in micrometeorology, errors and uncertainties still exist without necessary corrections. In this paper, we will focus on the effect of coordinate system on the eddy fluxes. Based on the data observed over four sites (one farmland site, one grassland site and two forest sites), the effects of three coordinate system transforming methods (Double Rotation-DR, Triple Rotation-TR and Planar Fit-PF)on the turbulent fluxes are analyzed. It shows that (i) the corrected fluxes are more or less than the uncorrected fluxes, which is related mainly to the sloping degree of surface, wind speed and wind direction; and (ii) pitch angle has a sinusoidal dependence on wind direction, especially in the regular sloping terrain; and (iii) PF method is something like the simplification of TR or DR,and there are not obvious distinctions in correction in sloping grassland and flat farmland, but PF method is not suitable for uneven and irregular forest sites.     

BDS-3新频点单点定位研究

针对目前有关北斗卫星导航系统(BDS-3)中MEO卫星(BDS-3M)增加的B1C、B2a新频点单点定位研究较少的现状,本文开展了基于新频点B1C、B2a的双频单点定位试验,结合国际GNSS监测评估系统(iGMAS)5个跟踪站连续10 d的数据,对BDS-3的新频点进行数据质量分析、双频伪距单点定位(SPP)和双频静态...     

加标回收在水质分析中的应用及回收率计算方法

阐述了水质分析中加标回收分析的方法步骤、条件控制及计算方法。当加标体积影响试样在加标水样中的浓度时,直接使用回收率理论计算公式的计算值,均较其真实的回收率偏低,且其偏低值随加标体积的增加而增大。根据加标回收分析的定义,分别以加标前后被测组分质量浓度(mg/L)的变化或含量(μg)的变化为依据,导出两个计算加标回收率的实用公式。采用该公式,加标体积可以不受严格控制,其计算结果与真实的回收率一致,适用于日常水质分析工作。     

钻孔揭露岩体构造特征确定露天采矿场推荐边坡角的方法应用探讨

文章从处理钻孔所揭露出的岩体构造资料入手,提出了位于类似热带地区的具有基岩露头少、堆积层厚大、矿体埋藏条件适宜露天开采等特征的矿床的露天采矿中确定推荐边坡角的一种方法。通过详细收集弱风化及未风化且节理开启或由方解石、石膏、粘土等软弱矿物充填的岩石的岩体构造特征,图解统计节理发育密度、节理与岩芯轴夹角随钻孔深度变化关系,并以相应钻孔深度倾角标准离差作修正,提出不同露天开采深度与稳定边坡角的关系。     

Analysis of Sediments and Soils by X-Ray Fluorescence Spectrometry Using Matrix Corrections Based on Fundamental Parameters

Wavelength dispersive X-ray fluorescence spectrometry (WD-XRF) is widely used for the analysis of soils and sediments using well characterised procedures. However, difficulties can occur with samples such as unknowns containing small amounts of ore materials and samples collected from contaminated sites where trace elemental concentrations can exceed the concentration range for routine analysis. We studied the performance of a commercially available method, based on fundamental parameters (FP) to correct matrix effects. The spectrometer was originally calibrated with elemental or simple compound calibrants. Samples were analysed as pressed powder pellets. Eighteen sediment and soil reference materials, three of them with certified values for some of their constituents, were used to evaluate accuracy, by comparing results with recommended values and their standard deviations (RV ± 2s) or certified values and their confidence intervals (CV ± Cl). When results fell systematically outside these intervals, calibrations were refined with geochemical reference materials. The best agreement of results with recommended and certified values was obtained when the contents of H₂O and C in each sample were included as matrix constituents during calculations. The detection limits of trace elements tended to be relatively high, because the measuring conditions employed were not maximised for sensitivity. The main advantage of the method tested was that it enabled the analysis of samples with high concentrations of trace elements and the determination of elements such as F, Bi, Sb and W, which are not commonly included in quantitative XRF analysis of geological samples.     

固体潮校正计算方法的改进

Excel被认为是当前功能强大、使用方便的电子表格软件。从1993年起,Excel就开始支持Visual Basic for Applications（VBA）．VBA是一款功能强大的工具,它使Excel形成了独立的编程环境。重力固体潮校正的计算改进前,重力计算中都是通过basic语言的程序设计在dos环境下来完成的。在大量应用windows的今天,dos的应用已经没有象windows那样普及。如果不能了解dos环境下的命令语句,根本就不能完成重力的计算工作。为此作者等对固体潮校正的计算进行改进,改进后达到了简单、高效的效果。