"三联式"资源定量预测与评价--数字找矿理论与实践探讨

随着信息技术的发展,矿产勘查已步入数字化,定量化研究的新阶段。“三联式”成矿预测及资源评价途径正是“数字找矿”的创新探索。“三联式”成矿预测以地质异常分析为基础,以成矿多样性分析与矿床谱系研究为指导,将地质异常,成矿多样性及矿床谱系三方面定量化研究紧密结合形成矿产预测及定量评价的有机切入点,是实现全面数字找矿的必由之路,也是矿产勘查评价领域应用信息技术的基础和前提。     

流域物质与水系及产沙间非线性关系实验研究

在３５．５６ｍｍ／ｈ．ｃｍ＾２定雨强的人工降雨条件下,组成物质中径分别为０．０２１ｍｍ、０．０６６ｍｍ及０．０７６ｍｍ的发育对比实验表明,产沙过程具有波动振荡衰减特征;水系发育以增加河道（沟道）数目及弯曲拉伸长度两种方式进行最小消能。水系分形维数正是这种消能的量度。水系分数维值随时间呈不对称上凹型曲线。对比分析表明：产沙过程的振荡性、衰减率,随物质变粗而加强,水系河道数目随物质变细而增多,河道随物     

岩石矿物组份质量转移的模糊聚类定量计算

本文根据岩石矿物组份质量分数值的定和特性 ,提出定量计算组份质量转移的新方法。该方法运用模糊动态聚类分析技术 ,通过计算复原定和差并判定差值类型 ,辅以相应的判别参数 ,逐步从中筛选出真恒量组份 ,再利用真恒量组份定值系数 ,计算出变组岩石矿物各组份的真实质量分数值和转移量值。笔者将该方法称为真恒量组份定值法 (TCF法 )。     

基于主成分分析和贝叶斯正则化方法的神经网络年最大洪峰流量预测模型探讨

针时水文预测建模中输入因子过多而导致神经网络结构规模过大,泛化能力差的问题,利用主成分分析和贝叶斯正则化方法对神经网络进行改进,优化网络结构,从而提高泛化能力。以洮儿河流域镇西站年最大洪峰流量预测为例,研究结果表明,改进的神经网络预测方法与传统的神经网络方法相比,泛化能力有显著提高,而且网络的收敛也比较稳定,实际预测中效果良好。     

主成分估计在多项式曲面拟合GPS高程中的应用

阐述了多项式曲面拟合GPS高程中参数数目对结果的影响,比较了传统最小二乘平差、主成分估计和岭估计在不同参数时的计算结果,主成分回归在不同参数时都可以取得比较满意的结果。     

Statistical empirical index of chemical weathering in igneous rocks: A new tool for evaluating the degree of weathering

Chemical weathering indices are useful tools in characterizing weathering profiles and determining the extent of weathering. However, the predictive performance of the conventional indices is critically dependent on the composition of the unweathered parent rock. To overcome this limitation, the present paper introduces an alternative statistical empirical index of chemical weathering that is extracted by the principal component analysis (PCA) of a large dataset derived from unweathered igneous rocks and their weathering profiles. The PCA analysis yields two principal components (PC1 and PC2), which capture 39.23% and 35.17% of total variability, respectively. The extent of weathering is reflected by variation along PC1, primarily due to the loss of Na₂O and CaO during weathering. In contrast, PC2 is the direction along which the projections of unweathered felsic, intermediate and mafic igneous rocks appear to be best discriminated; therefore, PC1 and PC2 represent independent latent variables that correspond to the extent of weathering and the chemistry of the unweathered parent rock. Subsequently, PC1 and PC2 were then mapped onto a ternary diagram (MFW diagram). The M and F vertices characterize mafic and felsic rock source, respectively, while the W vertex identifies the degree of weathering of these sources, independent of the chemistry of the unweathered parent rock.

The W index has a number of significant properties that are not found in conventional weathering indices. First, the W index is sensitive to chemical changes that occur during weathering because it is based on eight major oxides, whereas most conventional indices are defined by between two and four oxides. Second, the W index provides robust results even for highly weathered sesquioxide-rich samples. Third, the W index is applicable to a wide range of felsic, intermediate and mafic igneous rock types. Finally, the MFW diagram is expected to facilitate provenance analysis of sedimentary rocks by identifying their weathering trends and thereby enabling a backward estimate of the composition of the unweathered source rock.     

Analysis on the noises from continuously monitoring GPS sites

In this paper,we analyze the time series of site coordinates of 27 continuously monitoring GPS sites covered bythe Crustal Movement Observation Network of China over the whole country.The data are obtained in the periodfrom the beginning of the observation to the November of 2005.On the basis of data processing,we analyze thepower spectrum density of coordinate component noise at each site and calculate the spectral indexes manifestingthe noise property of each component.The spectral indexes indicate that for most sites,the noise of time series ofeach coordinate component can be addressed by the model of white noise flicker noise;and for a small amountof sites,it can be described by the model of white noise flicker noise random walk noise.We also quantita-tively estimate each noise component in the model by using the criterion of maximum likelihood estimation.Theresult shows that the white noise in the time series of GPS site coordinates does not constitute the main part ofnoise.Therefore,the error estimation of site movement parameters is usually too small,or too optimistic if weconsider the white noise only.Correspondingly,if this factor is not fully considered in explaining these movementparameters,it might mislead the readers.     

Implications of broad dose distributions obtained with the single-aliquot regenerative-dose method on quartz fine-grains from loess

Six samples were collected from a section of Peoria Loess in Eustis, North America, for optically stimulated luminescence (OSL) dating of quartz, and all except one (LV90) produced narrow dose distributions. A comparative study was conducted on this sample and on a ‘well-behaved’ sample (LV91), involving other dating methods and examination of the quartz OSL. These investigations revealed differences in the quartz OSL growth with dose, OSL response to thermal treatments and the range of components within the OSL signals. An ultra-fast component was found in LV90 that displayed a higher rate of sensitivity change than the fast component and this had a malign influence on the determination of the equivalent dose. The distinctive luminescence characteristics of LV90 imply either a change in wind dynamics and/or the source area for the silt.     

提高地磁绝对观测数据精度的有效途径

经过长期观察发现用CZM-2型核旋仪(及其同类仪器)进行定点观测读数时,运用分量仪线圈“单向”旋转的方法进行分量观测,再加上做好一些其它辅助措施,能够充分消除人为因素和仪器本身误差所带来的影响,明显提高仪器的观测精度,达到使观测资料更加准确的目的。     

一种简化的Helmert方差分量估计算法

Ｈｅｌｍｅｒｔ方法是通过求出两类观测值的单位方差,来修正其先验权,用迭代法最终求得正确的权。本文提出,如果已知两类观测值的单位方差之比,即可定出正确的权,从而使计算简单化。