边坡稳定可靠性的随机有限元分析

随机有限元法可以处理土性参数的变异性和空间相关性。对二阶摄动随机有限元法的摄动理论和程序进行了研究，提出了偏导矩阵的组集方法，采用正态分布随机变量的正交变换法来提高计算效率。考虑土性参数随机场作用和土性指标之间的互相关性，建立边坡局部抗剪和总体稳定性可靠度的随机有限元分析模型，对某实际土坡进行了可靠度计算，计算结果较为符合实际。     

Seismic interaction in linearly connected electrical substation equipment

An electrical substation consists of a complex set of equipment items that are interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic excitation. This interaction is believed to be responsible for some of the observed substation equipment damage in recent earthquakes. This paper investigates the interaction between two equipment items connected by a linear spring‐dashpot or spring‐dashpot‐mass element representing a conductor bus. It is found that the interaction between the two equipment items may significantly amplify the response of the higher‐frequency equipment item. The influences of various key parameters on the interaction effect are quantified. Means for reducing the adverse interaction effect are described. Copyright © 2001 John Wiley & Sons, Ltd.     

Preparation and Certification of High-Grade Gold Ore Reference Materials (GAu 19-22)

Two types of gold deposit with both good homogeneity and a high-grade of gold were selected to prepare four gold ore reference materials (GAu-19,GAu-20,GAu-21 and GAu-22) by the Institute of Geophysical and Geochemical Exploration (IGGE),China.Seven laboratories participated in the certification programme. Volumetric methods for GAu19-21 and atomic absorption spectrometry for GAu-22 were used for the homogeneity testing,the coefficient of variation being found to be less than 3%.After sample digestion and preconcentration,the samples were analysed by flame atomic absorption spectrometry (AAS),colorimetry,neutron activation analysis (NAA)and volumetric analysis. The certified values for the gold concentration in GAu19-22 are 18.3 μg g -1, 32.3 μg g -1, 53.0 μg g -1 and 5.72 μg g -1,respectively.     

一种基于马尔可夫随机场的影像纹理分类方法

针对纹理影像先估计出其马尔可夫随机场参数，后运用多元统计分析中模糊聚类分析的数学方法进行定量分类，从而为解决划分上的不确定性现象找出描述方法，获得客观的分类结果     

Cyclic strength and deformation of crushable carbonate sand

Cyclic triaxial tests have been carried out on a skeletal carbonate sand from the west coast of Eire. Results are presented for undrained cyclic shear tests on samples with 80% of relative density consolidated under both isotropic and anisotropic conditions. Failure was defined as a 5% double amplitude cyclic strain and a 5% peak axial strain for stress-reversal and non-reversal stress conditions, respectively. Using this definition the cyclic strength for isotropically consolidated samples was affected by the confining pressure although the angular platey nature of the sand resulted in higher cyclic strengths than for a comparable silica sand. For anisotropically consolidated samples the cyclic strength increased with increasing initial static shear stress while on the other hand the cyclic strength normalised in the usual way with respect to the initial confining pressure decreased as this pressure increased.     

An extreme value analysis of the flow of Burbage Brook

An extreme value analysis of the flow of Burbage Brook is carried out by modelling peaks over a high threshold. The aims are to illustrate recently developed statistical techniques and to report on interesting features of the flow of the brook over a 58-year period. Peak flows are found to show marked seasonal variation and a downward trend. Then-year return level is estimated for various values ofn, and the reliability of the estimates is assessed.     

The Reliability of Using the Iterative Proportional Fitting Procedure*

This paper demonstrates the utility of the iterative proportional fitting procedure (IPF) in generating disaggregated spatial data from aggregated data and evaluates the performance of the procedure. Estimates of individual level data created by IPF using data of equal-interval categories are reliable, but the performance of the estimation can be improved by increasing sample size. The improvement usually is enough to offset the increase in error created by other factors. If the two variables defining the cross-classification have a significant interaction effect and the number of categories in each variable is larger than two, then IPF is preferred over an independent model.     

相对点位中误差及其在工程测量中的作用

阐述相对点位中误差的概念及其在工程测量中的作用,介绍相对点位中误差及相对误差椭园计算方法,以示例说明点位中误差和相对点位中误差的意义和作用。     

夏季青藏高原地区降水和低涡的数值预报试验

本文首先分析了１９７９年６—７月的ＦＧＧＥIIIｂ级资料风场和相对湿度场在青藏高原地区的偏差，指出在高原西部应予以订正。然后利用一有限区域模式，通过综合订正初始风场和相对湿度场，改进模式部分物理过程，并提高其水平分辨率，共设计了６组预报试验，对该年的两例高原低涡切变线降水过程进行了２４小时预报。结果表明，利用改进了的初始场和部分物理过程，可明显改善高原地区的降水预报，并在一定程度上改善了流场的预报，即上述改进方案是可行的；但在高原地区嵌套预报方案尚待修改，还应继续努力提高模式对高原低涡流场的预报能力。