High Precision Ru, Pd, Ir, Pt, Re and REE Determinations in the Stevns Klint Cretaceous-Tertiary Boundary Reference Material (FC-1) by Isotope Dilution Multiple Collector Inductively Coupled Plasma-Mass Spectrometry

We present high precision Ir, Ru, Pt, Pd, Re and rare earth element (REE) determinations by isotope dilution multiple collector-ICP-MS on the Cretaceous-Tertiary boundary sedimentary reference material FC-1. Samples for platinum-group element measurements were digested in Carius tubes followed by acid digestion. The platinum-group elements were subsequently separated by anion exchange chemistry and determined by multiple collector-ICP-MS. The accuracy of the platinum-group element analyses have been verified by comparative analyses of the reference materials WITS-1 and GP13 (sample size 0.5-1 g). Replicate analyses of FC-1 (sample size 0.2 g) exhibit good reproducibility (RSD < 5%) for all the analysed platinum-group elements. REE data also exhibit excellent reproducibility (RSD < 0.5%), which indicates that this sample is homogeneous for the determination of the platinum-group elements and REE at the 0.2 g level.     

弹性模量、波速与应力的关系及其应用

为充分了解不同尺度地质系统的岩石动力学特征,更好利用不同规模勘探资料有效解释地质系统的特征,在岩石物理实验对岩石弹性模量、波速与应力的关系进行研究总结的基础上,探讨野外实际地震勘探中地震波速与地应力的关系。研究表明,岩石、岩体或地质系统是多相(固液气)、多种矿物、各种构造的综合体,不论尺度如何均可以用多重介质孔隙裂隙地质模型描述,而波速是一定尺度不均匀地质体的等效波速,在一定地质条件下,各种尺度介质波速、岩石弹性模量与有效应力存在依存关系。坚硬的岩石通常很脆,如果岩石处于很大的应力之下,应力的释放将在岩石中产生微裂隙,微裂隙会降低地震速度。只要把岩石恢复到原来的应力状态就可能消除所引发的微裂隙。在岩体未达到破坏时,应力越大,波速愈高。压力释放引发的微裂隙有助于现场确定最大/最小水平应力方向,波速的椭圆长轴即为主应力方向。而上覆地层压力不变(或变化很小),净储层压力的影响正好与储层压力对地震特性的影响相反。随着净储层压力的增加,所有岩石的地震特性都增高。这种增高的量级取决于若干其它的因素(孔隙形状、孔隙度、孔隙流体、岩性等等)。不论野外地震勘探还是实验研究,地震波速与地应力的一致性为地质系统的正反演解释提供了宏观控制依据:通过测量弄清     

水利水电地下工程发展现状

随着西部大开发的进展,水利水电地下工程也出现迅猛的发展势头。其特点是规模不断向大型化与洞室群的复杂化发展。同时,施工机械化程度的不断提高,使得施工速度和施工质量的提高都是前所未有的,特别是近十年来的发展,将我国的地下工程的设计与施工水平推向一个崭新的高度。     

初始地应力场多方程回归分析

在初始地应力场分析问题中,采用了多方程回归方法。该模型同时考虑了一组变量(包括自变量与因变量)之间的所有关系。在此基础上,采用逐步回归法进行计算,进一步提高了计算精度。由此,得到了回归效果更显著的初始地应力场。     

基于 BP神经网络和回归分析的隧洞塌方高度预测模型

隧洞塌方的发生与多种因素有关,本文以小关子水电站引水隧洞为例来讨论如何用相关的因素建立隧洞塌方高度的预测模型。经过分析后认为该隧洞塌方高度主要与断层在洞向上的视倾角和厚度,水电围岩分类评分和围岩的RQD值有关。先以此四个因素为自变量,塌方高度为因变量建立起隧洞塌方高度的多元回归模型,利用回归模型的结果对BP神经网络预测模型所需的样本进行扩充,进而建立起BP神经网络塌方高度预测模型。     

南极和北极地区在全球变化中的作用研究

多次波问题是海洋地震勘探中最突出的问题之一 ,如何有效地压制多次波是解决问题的关键。多次波数据处理的压制方法和技术分为运动学的滤波方法和动力学的波动方程方法两大类。波动方程方法由于几乎不需要先验信息和具有较好的压制效果 ,已经成为多次波压制方法和技术发展的主要趋势。文章首先对波动方程方法进行了较全面的综述 ;然后 ,对波动方程方法中的反馈迭代反演方法做了深入的讨论 ;最后 ,通过理论模型的正反演计算 ,验证了运用波动方程反馈迭代反演法不需要知道震源函数、地下岩层结构和岩性等先验信息。此方法适用于压制多种类型的多次波 ,具有优异的振幅保真性等独特的优点。     

Managing spatial uncertainty using attribute,geometric, and neighborhood measures in an empirical rule-based model approach

 A rule-based model for managing uncertainty in spatial databases is presented. The overall goal of the model is to allow a user to assign to a single map class each polygon whose class is not entirely certain using more information than only the map class attributes of such polygons (that are herein termed abjects). This situation might arise when multiple map realizations of an area are available and interpreters/cartographers are not in agreement as to what class is present at a given location or when a digital image is classified by algorithmic/probabilistic means. The scale-based model developed relies on attribute, geometric, and neighborhood measures of abjects arranged in a hierarchical rule-based structure. Structural knowledge of these measures leads to the procedural knowledge that determines what action – e.g., merge, reclassify, retain – is to be taken for a given abject. The wider applicability of the model and associated methodology is also discussed. Received: 5 July 2001 / Accepted: 11 April 2002     

冈底斯岩带热演化史的MDD模式新证据Ⅰ

本文首次报道在我国实验室利用特定的40Ar/39Ar阶段加热程序和MDD械处理得到的钾长石冷却曲线，加之黑云母和磷灰石的年龄测定结果进一步讨论了冈底斯岩带的热演化史。     

两类多河道河流的形式模式及河道稳定性比较

在多河道河流中，网状河流作为有别于分汊河流和辫状河流的河型而提出已经引起人们的注意，但它与分汊河流的区别常常被忽略。为了阐明二者的根本差别，力求从多河道形成模式上对二者进行比较研究。通过对长江下游分汊河流及荆江风状河流特定河段形成历史及方式的探索，提出河道内的江心洲化模式和河漫滩上的河道化模式分别是分汊河流和网状河流形成的基本途径。由此而决定了网状河道具有分汊河流更高的稳定性。     

Flood hazard in Hunan province of China: an economic loss analysis

Natural and man-made disasters have been increasing and affecting millions of people throughout the world. Floods are the most common natural disasters affecting more people across the globe than all other natural or technological disasters and also are the most costly in terms of human hardship and economic loss. In order to explore the total economic loss, components of economic loss, and factors influencing economic loss during flooding, a retrospective study was carried out in year 2000 in areas that suffered floods in 1998 in Hunan province, China. A total of 10,722 families were investigated using a multistage sampling method. We found that the total economic loss to the 10,722 families investigated was US$ 8.925 million; translating into an average economic loss of US$ 832.45 per family and US$ 216.75 per person. Economic loss related to property loss, income loss, and increased medical cost accounted for 57.38%, 40.00%, and 2.62% of the total economic loss, respectively. Economic loss was significantly related to a family’s pre-flood income; duration of the flood; severity of flood; and type of flood. River floods yielded the highest economic loss and drainage problem floods yielded the lowest loss. We recommended that flood-related preventive measures should focus on the prevention of river floods and shortening the duration of floods with the view of significantly minimizing economic losses associated with floods.