GPS技术在山区石油地震勘探测量中的应用

针对GPS技术在山区石油地震勘探测量中的工作方式,结合2007年度南盘江一桂中地区二维地震大剖面资料采集应用GPS的工程实例,介绍GPS技术应用的新进展。通过GPS静态测量和应用RTK技术放样物理点,从测前准备、数据处理、精度分析等方面,阐述提高作业精度、有效进行质量控制的方法,旨在最大限度地发挥GPS技术在山区施工中的作用。     

基于光谱和纹理的SVM矿化蚀变信息提取研究

针对传统矿化信息提取方法单一,利用光谱或纹理、信息量相对较少、需要大量样本的缺陷,利用基于光谱和纹理的支持向量机(SVM)原理,建立矿化信息提取模型.选择青海泽库县析界日地区作为典型研究区.首先提取研究区光谱和纹理信息,选取训练样本;然后求解最优超平面,进而确定决策函数;最后泛化推广识别其他待识别的样本.通过所提取的遥感蚀变异常信息与重砂异常点叠加分析,叠加基本吻合;从野外实地验证来看,均发现了不同程度的矿化现象,并指出了5个重点异常区.     

区域似大地水准面确定的最小二乘支持向量机方法

支持向量机(SVM)是近年来发展起来的机器学习的新方法,它较好地解决小样本、非线性、高维数、局部极小点等实际问题.文中研究支持向量机的拓展算法--最小二乘支持向量机(LSSVM),并将其应用于确定大面积复杂似大地水准面.通过工程实例并与神经网络模型和二次曲面多项式拟合模型相比较,验证确定区域似大地水准面的LSSVM方法的有效性.     

球面线要素的多分辨率实时简化方法

在分析球面3维数据可视化特点的基础上,提出了视点相关的球面矢量数据LOD简化方法,基本原理是：以视点为基础在屏幕空间获取投影误差,反投影到模型空间得到动态简化阈值,并结合Douglas—Peucker算法,对矢量数据进行多分辨率实时简化表达。最后,开发实验系统并对相关方法进行了验证。结果表明：在不影响球面图形可视化效果下,数据量减少了约4-5倍,有效地提高了图形渲染速度和效率。     

Using Topological Relationships to Inform a Data Integration Process

When spatial datasets are overlaid, corresponding features do not always coincide. This may be a result of the datasets having differing quality characteristics, being captured at different scales or perhaps being in different projections or datums. Data integration methods have been developed to bring such datasets into alignment. Although these methods attempt to maintain topological relationships within each dataset, spatial relationships between features in different datasets are generally not considered. The preservation of inter‐dataset topology is a research area of considerable current interest. This research addresses the preservation of topology within a data integration process. It describes the functional models established to represent a number of spatial relationships as observation equations. These are used to provide additional information concerning the relative positions of features. Since many topological relationships are best modelled as inequalities, an algorithm is developed to accommodate such relationships. The method, based on least squares with inequalities (LSI), is tested on simulated and real datasets. Results are presented to illustrate the optimal positioning solutions determined using all of the available information. In addition, updated quality parameters are provided at the level of the individual coordinate, enabling communication of local variation in the resultant quality of the integrated datasets.     

Modelling Positional Uncertainty of Line Features by Accounting for Stochastic Deviations from Straight Line Segments

The assessment of positional uncertainty in line and area features is often based on uncertainty in the coordinates of their elementary vertices which are assumed to be connected by straight lines. Such an approach disregards uncertainty caused by sampling and approximation of a curvilinear feature by a sequence of straight line segments. In this article, a method is proposed that also allows for the latter type of uncertainty by modelling random rectangular deviations from the conventional straight line segments. Using the model on a dense network of sub‐vertices, the contribution of uncertainty due to approximation is emphasised; the sampling effect can be assessed by applying it on a small set of randomly inserted sub‐vertices. A case study demonstrates a feasible way of parameterisation based on assumptions of joint normal distributions for positional errors of the vertices and the rectangular deviations and a uniform distribution of missed sub‐vertices along line segments. Depending on the magnitudes of the different sources of uncertainty, not accounting for potential deviations from straight line segments may drastically underestimate the positional uncertainty of line features.     

附加约束条件的序贯平差

从观测量分组的参数平差出发,详细推导了附加约束条件的序贯平差及其精度估计,讨论了附加约束条件的抗差序贯平差的计算过程.算例表明,推导的公式正确有效,简单实用,附加约束条件的序贯平差抗差估计能有效地抵制粗差的影响.     

动态最小二乘支持向量机学习算法

针对大样本集的训练问题和动态训练样本的模型更新问题,提出了动态最小二乘支持向量机学习算法.该算法充分利用已建好的模型,逐渐加入新样本,并可删除位于任何位置的非支持向量,避免了矩阵求逆运算,保证了算法的高效率.大坝变形及电离层延迟两个时间序列的预报实例表明,该算法具有计算时间短、预报精度高的特点.     

等截面单桩抗拔承载性状试验研究

在基坑中对等截面单桩进行了抗拔静载试验，在桩身设置应变式钢筋计，成功测得桩身各截面的应变数据。分析试验所得数据，对试验抗拔桩抗拔系数的取值、侧摩阻力的发挥、混凝土桩身的开裂等进行了探讨，相应给出了抗拔桩的设计建议。     

复合土钉墙支护技术在某大型软土基坑围护中的应用

根据拟建建筑基坑的工程地质条件、周边环境条件、基坑开挖深度等特点综合考虑，对基坑分段采用超前微型桩支护加土钉墙、放坡加土钉墙2种复合支护方案。实践证明，该工程所采用的多种复合式支护实施方案，技术安全可靠，经济合理。