Reflection of waves from the boundary of a random elastic semi-infinite medium

In this paper the smooth perturbation technique is employed to investigate the problem of reflection of waves incident on the plane boundary of a semi-infinite elastic medium with randomly varying inhomogeneities. Amplitude ratios have been obtained for various types of incident and reflected waves. It has been shown that an incidentSH orSV type of wave gives rise to reflectedSH, P andSV waves, the main components beingSH andP, SV in the respective cases. The reflected amplitudes have been calculated depending upon the randomness of the medium to the square of the small quantity , where measures the deviation of the medium from homogeneity. An incidentP-type wave produces mainly aP component and also a weakSH component to the order of ². The reflected amplitudes obtainable for elastic media are also altered by terms of the same order. The direction of the reflected wave is influenced by randomness in some cases.     

青岛市海雾海气通量观测及其作用初探

概述１９９３年６月下旬－７月上旬在青岛市小麦岛东侧进行的风、温、湿梯度观测。其资料经迭代计算得到了黄海北部、青岛市近海平流雾季节海气间动量、热量和水汽的通量。并对７月１—２日的一个海雾过程进行了微物理分析。     

经济预测模型在土地规划中的应用与分析

主要介绍土地规划时需用到的几种预测模型 ,具体阐述了几种模型的原理 ,并以抚州地区的总人口历史数据为例 ,进行实际的预测与分析 ,从而总结各种模型的优缺点 ,选择最合适的土地规划预测模型。     

Estimating actual rainfall from satellite rainfall products

The lack of uncertainty measures in operational satellite rainfall (SR) products leads to a situation where users of the SR products know that there are significant errors in the products, but they have no quantitative information about the distribution of these errors. The authors propose a semiparametric model to characterize the conditional distribution of actual rainfall (AR) given measures from SR products. The model consists of two components: a conditional gamma density given each SR, and a smooth functional relationship between the gamma parameters and SR. The model is developed for monthly rainfall, estimated from a satellite with sampling frequency once a day, averaged over an area of 512 × 512 km² in the Mississippi River basin. The conditional distribution results are more informative than deterministic SR products since the whole conditional distribution enables users to take appropriate actions according to their own risk assessments and cost/benefit analyses.     

基于双差观测序列曲线拟合实现GPS静态定位基线实时解算

对于ＧＰＳ静态差分定位的实时算法而言,能否实时地解决观测数据的存储、卫星失锁、载波相位周跳、多径效应以及计算速度等问题是保证基线的实时解算和定位成功率的重要因素。本文利用载波相位双差观测时间序列可用直线或高次曲线进行很好拟合的特性,设计了一种静态定位的实时算法,能解决上述实时定位中的特殊问题。     

Micro-sequential contour blasting—how does it influence the surrounding rock mass?

The optimal delay time between the contour holes in rock blasting has been studied by theoretical and empirical research in Sweden, regarding ground vibrations, increase in crack frequency, radial crack length and finally overbreak (half cast factor). The model test presented in this paper concerns controlled contour blasting in tunnelling and the full-scale blasts concern tunnelling, road cutting, and dimensional stone quarrying. The results indicate that the microsequential contour blasting technique (contour holes fired in sequence and with a delay in the order of 1–2 ms) is superior to simultaneous initiation both regarding blast-induced ground vibrations and crack frequency increase in the rock mass. Both these evaluation methods reflects the conditions deeper in the remaining rock mass. Simultaneous initiation, however, is superior to micro-sequential contour blasting both regarding the half cast factor and the length of radial cracks emanating from the blastholes. These two parameters are more related to the surface conditions after blasting. The industrial applications of this new knowledge are the use of micro-sequential contour blasting when ground vibrations are of greater concern than the contour, for example, in trench blasting or quarrying in urban areas, and the use of simultaneous initiation when an even rock surface is of high priority.     

离散光滑插值方法在地球物理位场中的快速实现

研究并探讨了1种新的插值方法-离散光滑插值方法及其在地球物理位场中的快速实现。首先由待插值点与巳知点之间的拓扑关系建立线性约束，进一步结合场满足Laplace方程，建立离散光滑插值联立方程组，采用预条件共轭梯度求解该方程组。为更好地提高计算效率，在求解过程中采用螺旋坐标系和Wilson-Burg谱分解，将二维数据转换到一维空间处理。通过理论模型和实际资料计算，该方法适合地球物理位场特征，插值效果好，速度快。     

射线类偏移成像中的模型平滑处理研究

本文从能量泛函的角度着手,基于速度梯度,采用最速下降法推导了基于偏微分方程的速度模型平滑公式,用于解决射线类偏移成像过程当中速度模型的平滑处理问题.同时针对偏微分方程速度模型平滑系数中阈值k的选取对速度模型空间结构的影响,在简单的高速体速度模型上分析了不同k值的选取对原始速度模型空间结构的改变,并通过射线路径和时间场的对比分析证明偏微分方程速度模型平滑处理相对于卷积算子平滑的优越性.最后通过在Marmousi、Sigsbee2A原始速度模型以及平滑处理后的速度模型上的成像结果分析验证偏微分方程模型平滑的有效性.     

MAPGIS软件中交互式矢量化的应用

在应用MAPGIS软件进行线条矢量化时存在着常规输入线的耗时及自动矢量化效果太差问题,交互式矢量化利用图形分层、人工干预线条走向、线条抽稀、线条光滑等手段,可有效克服矢量过程中出现的线条重叠和偏离现象,保证图件矢量化的效果。合理使用功能键进行退点、转换线向及图层屏蔽等技巧,可方便、快捷、美观的完成图形矢量化。     

白噪声中f~(-2)随机过程的最优估计

从功率谱的角度分析了白噪声中f-2随机过程的最优估计问题，推导了线性估计方法的精度极限，并通过对若干线性估计方法的精度进行分析和比较，得到了一些有意义的结论。