Experimental investigation on the effect of the mode of deposition on the pore-access size distribution of sand

It is well known that the specimen preparation method and the resulting sand fabric significantly affect sand behaviour and sand liquefaction resistance. In this study, a simple experimental method namely tensiometric method is presented for evaluation of the effect of the samples reconstituting methods on microstructure and the pore-access size distribution of sands. Specimens were prepared using dry funnel pluviation (DFP) and wet deposition (WD) at two densities Dr = 40% (loose state) and Dr = 80% (dense state). The water-retention curve of a sand specimen is evaluated using a technique similar to the hanging column method by application of a step-by-step variation of suction and measure of the corresponding changes in water content. The pore-access size distribution is then evaluated from the water-retention curve. In this experimental study the effects of the mode of deposition and the uniformity coefficient on the pore-access size distribution are investigated. It was found that the specimen generated by the WD method contained a higher percentage of pore size, contrary to the specimen prepared by the DFP which contained a limited percentage of pore size, causing a great influence on the mechanical behaviour of the specimens.     

Quantitative Risk Assessment of Catastrophic Debris Flows through Numerical Simulation

The risk assessment is not only the one of the most effective soft measures in natural hazard prevention, but also is the base of hazard risk management. On account of the specificity of various elements at risk and debris flow mechanism, the theoretical system and technical procedure of debris flow quantitative risk assessment for buildings and roads were established in the mountaineous area of Southwest China, which included three sections: ①To represent debris flow hazard quantitatively using the intensity index IDF through FLO-2D simulation; ②To build debris flow physical vulnerability curve based on the loss exceedance-probability from Qipan gully debris flow case; ③To quantify the expected loss of the important elements at risk based on their database after setting the future debris flow scenarios. The case study of Yangling catchment indicated that the responding mechanism between elements at risk and debris flow physical mechanism was described quantitatively by this quantitative risk assessment system, which can contribute to the construction planning and prevention measure making in the southwestern mountainous area.     

动线法自动制图的关键算法设计与实现

动线法(即运动符号法),能综合表达空间实体或现象的作用方向、运动路线、数量增减、质量变化等,是计算机地图制图的重要方法之一。本文分析了直线动线符号在信息表达中存在的局限性,以及曲线动线符号所具有的优势,对曲线动线符号的组织形式、位置、颜色、方向、宽度、曲率等方面作了分析,同时对曲线动线符号提出了制图算法,具体包括:曲线符号模型算法、避障路径算法、汇流与分流算法等;并以MapServer开源软件作为平台,利用C++语言进行程序设计,建立了Web的动线法自动制图算法实验系统,且以河南省流动人口数据为例,进行算法应用分析。结果表明:该算法极利于时空数据的可视化表达,具有很好的应用前景。     

中国人口空间分布不均匀性分析及其可视化

中国人口空间分布的不均匀性是一种客观存在的现象,自从1935年胡焕庸先生提出"爱辉-腾冲线"以来,中国人口东西部的不均匀现象并没有发生显著的变化。这种不均匀不仅仅存在于"胡焕庸线"两侧,而是广泛存在的。本文引用经济学家研究收入分配平均程度常用的LORENZ曲线方法,结合相关图、表,对中国人口空间分布的不均匀性进行研究。通过对曲线特征点的分析,结合地图可视化可以形象地反映人口空间分布的特点,同时对人口空间分布进行定量化描述。     

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基于离散傅里叶变换的线要素节点压缩方法

相较于传统删减顶点的线要素综合方法,基于傅里叶变换的线要素综合更能保留曲线的全局特征,但现有的傅里叶综合方法无法自动减少和控制点数,更多适用于曲线的平滑及多尺度表达。因此本文提出一种利用离散傅里叶变换进行线要素综合的方法。对曲线进行离散傅里叶变换,获得有限项傅里叶描述子;根据期望的压缩比对傅里叶描述子进行截断;根据截断后的描述子项进行离散傅里叶逆变换获得化简曲线。本文提出的这种傅里叶方法能够减少化简后曲线顶点数,适用于地图综合领域。本文通过四组实验验证了算法的可行性,展示其如下优点：① 能够在相应尺度上对线性地物进行平滑、渐进的化简和表达② 在现有傅里叶变换法的基础上能够保留曲线原顶点;③ 以顶点数作为综合过程参数,能够自动减少曲线顶点数;④ 相较于传统节点压缩方法,更注重整体形态的化简,在综合过程中能更好地保留曲线的整体特征;⑤ 在转换尺度较大的综合过程中,相较于传统节点压缩方法所保留的几何精度更高。     

瞬态瑞雷面波法研究及其在边坡工程中的应用

瞬态瑞雷面波法作为一种新的物探方法,它的原理主要是通过激发和接收不同频率的瑞雷波的传播速度,来探测不同深度或者距离的岩石的物理力学性质,为了解地下岩石性质提供理论依据。本文结合工程实例对瑞雷面波的基本原理和数据解释的方法进行深入的探讨,利用瑞雷波的频散曲线对浅部的岩层进行分层,为寻找潜在滑动面提供理论依据。     

求算界限温度日期的一种新方法──样条函数插值法

本文根据某站点各月平均气温,通过计算机,用样条函数插值法模拟年温变化曲线,进而直接求算出主要界限温度初终日期、间隔日数及其相应积温,并与用滑动平均法得出的结果进行了比较检验。     

改进二值LFI医学图像分割模型

基于区域活动轮廓模型在处理医学特定分割目标时,受到图像背景影响较大,难以提取目标边界轮廓.针对这一问题,提出一种改进LFI模型.该模型构造出局部适当图像来逼近原图像,且引入吸附因子约束曲线演化方向,恢复曲线演化渐进性,使得分割具有针对性.采用二值水平集方法实现整个分割过程,避免了传统水平集数值不稳定性.实验结果表明该方法可以快速有效地分割特定医学图像目标.     

蛇纹石物相的X射线衍射定量分析方法

X射线衍射分析法虽然是部分国家测定蛇纹石的标准方法,但由于现有方法缺乏试验数据的支撑,其检测质量的监控得不到保证,我国目前仍未采用X射线衍射法作为蛇纹石物相定量分析的标准方法。应用X射线衍射仪,根据不同含量分别采用标准曲线法和K值法定量测定蛇纹石含量,通过精密度试验及其协作试验、准确度（包括加标回收）试验等一系列测试,对结果进行统计分析。研究成果可为分析质量的监控及分析方法的评价等提供依据,为建立我国蛇纹石物相定量分析标准方法提供技术支撑。