Multivariable spatial prediction

For spatial prediction, it has been usual to predict one variable at a time, with the predictor using data from the same type of variable (kriging) or using additional data from auxiliary variables (cokriging). Optimal predictors can be expressed in terms of covariance functions or variograms. In earth science applications, it is often desirable to predict the joint spatial abundance of variables. A review of cokriging shows that a new cross-variogram allows optimal prediction without any symmetry condition on the covariance function. A bivariate model shows that cokriging with previously used cross-variograms can result in inferior prediction. The simultaneous spatial prediction of several variables, based on the new cross-variogram, is then developed. Multivariable spatial prediction yields the mean-squared prediction error matrix, and so allows the construction of multivariate prediction regions. Relationships between cross-variograms, between single-variable and multivariable spatial prediction, and between generalized least squares estimation and spatial prediction are also given.     

龙口油页岩半焦和煤混合燃烧特性研究

通过对龙口褐煤、油页岩和半焦进行混合试验,研究了混合前后发热量、挥发分、灰分、水分、硫分和灰熔融性软化温度的变化特征,掌握了性价比最高的最佳配比,为小颗粒油页岩、煤和半焦的混合燃烧发电提供了科学依据。     

利用点云切片提取技术分析桥梁形变

三维激光扫描技术作为近年来发展迅速的测绘手段,在桥梁健康监测中,已经成为监测技术的重要组成部分。本文以武汉市某跨江大桥为例,首先采用Trimble SX10三维激光扫描仪对桥梁进行长期监测扫描,并对桥梁钢结构和桥墩的点云进行切片;然后在Trimble Business Center 和 Trimble RealWorks软件的帮助下对每期的扫描点云进行处理,提取桥拱断面点坐标并对桥墩切片点云进行最佳垂直圆柱体拟合,获取拟合平面中心点坐标;最后对比分析每期特征点平面坐标的偏差和三维偏移量。本文研究成果验证了三维激光扫描仪在桥梁变形监测中的可行性,丰富了桥梁监测数据的表现形式,可以为相关研究提供依据和参考。     

关于奇异线性模型最好线性无偏估计的计算

讨论了奇异线性模型最好线性无偏估计(BLUE)的计算问题。利用分块求逆的技术，给出BLUE的一种新的表达式，其计算量比直接利用C．R．Rao所给公式的小。对新表达式的计算，给出半正定矩阵广义逆的分块求逆算法及消去变换算法。     

黄泛区路基强夯时超孔隙水压力变化规律试验研究

滨德高速公路所经地区主要由黄河冲积而成,场区地层以粉土和粉质黏土为主。在试验区不同地层深度处埋设孔隙水压力计,通过观测、分析强夯各个过程中超孔隙水压力的变化规律,得出以下结论:在2 000 kN.m夯击能的作用下,第1～2遍夯击时最佳夯击数为8～9击,第3遍夯击时最佳夯击数为6～8击;夯击后,浅层的超孔隙水压力基本均大于深层的超孔隙水压力,消散时间也相对较长,并且浅层孔隙水压力受夯击影响的水平距离较深层的大;在2 000 kN.m夯击能的作用下,强夯最大影响深度为8～9 m,有效加固深度为6～8 m,有效加固深度系数α=0.134～0.179;6～7 m深处孔隙水压力水平最大影响距离小于10 m,有效影响宽度基本为5～7 m。     

Suspended solid yield from forest harvesting on upland blanket peat

Forest harvesting activities, if not carefully carried out, can disturb the forest soils and can cause significant suspended solid concentration increases in receiving water. This study examined how harvesting, following forestry guidelines, influenced suspended solid concentrations and loads in the receiving water of a blanket peat salmonid catchment. The study site comprised of two forest coupes of 34‐year‐old conifers drained by a first‐order stream. The upper coupe was not felled and acted as a baseline ‘control’ catchment; the downstream coupe was completely harvested in summer 2005 and served as the ‘experimental’ catchment. Good management practices such as the proper use of brash mats and harvesting only in dry weather were implemented to minimize soil surface disturbance and streambank erosion. Stream flow and suspended solid measurements at an upstream station (US) and a downstream station (DS) in the study stream commenced over a year before felling took place. The suspended solid concentrations, yields and release patterns at US and DS were compared before and after harvesting. These showed that post‐guideline harvesting of upland blanket peat forest did not significantly increase the suspended solid concentrations in the receiving water and the aquatic zone need not be adversely affected by soil releases from sites without a buffer strip. Copyright © 2010 John Wiley & Sons, Ltd.     

人工边坡治理设计最优坡角确定方法浅析

人工边坡治理包含削坡开挖、坡体加固、土地征用、工程环境等内容，各子项工程成本均与设计开挖坡角有密切关系。作者阐述了设计最优坡角的工程意义，并通过工程技术与成本诸要素分析，提出了最优坡角的确定方法。     

稳健最优不变二次无偏估计

导出了稳健最优不变二次无偏估计、稳健最小范数二次无偏估计、稳健Helmert估计,并说明了最优不变二次无偏估计、最小范数二次无偏估计以及Helmert估计等均是稳健最优不变二次无偏估计的特例。     

具有更佳分辨率小波分解的遥感影像纹理分类*

首先提出了具有更佳分辨率的小波分解,然后研究了基于该小波分解特征的影像纹理分类,并对25类地貌遥感影像在两种不同分解方式、两种不同滤波器长度及三种不同分辨率下进行了分类试验,取得了较高的分类正确率。     

最优小波包变换在地震信号去噪中的应用

应用最优小波包变换,采用取决于节点噪声时频特征的相关阈值,对模拟地震波到达的加噪合成信号、SDAES数字声发射仪采集的微震实验信号、NIED观测台站记录的日本2007年能登半岛地震信号进行去噪,并和基于小波变换的其他方法进行了去噪效果比较.结果表明,该方法获得的信号信噪比(SNR)高、失真低,体现出了总体优越性.