Soil erosion due to rainfall impact with no inflow: a numerical solution with spatial and temporal effects of sediment settling velocity characteristics

Dynamic changes take place in the nature of sediment eroded from bare soil at low slopes by rainfall impact when there is no inflow of water at the top of the eroding slope. This relates initially to fine soil sediment not settling back onto the soil after the rainfall impact. Coupled partial differential equations describing such dynamic changes have been solved numerically for a bed of soil, bounded at its upper end, and subject to a constant rainfall rate. This solution allows prediction of the change with time and downslope distance in the concentration and settling velocity (or size) characteristics of eroding sediment, allowing critical evaluation of the assumption of space-independent sediment characteristics made in prior approximate analytical solutions of the equations involved. Following the determination of as yet unpredictable soil-related parameters in the equations, the solution was tested by comparison with experimented data on two soils of contrasting structural stability, namely a vertosol [The Australian Soil Classification (1996)] and a aridisol. Investigations included the determination of a minimum number of sediment size classes required to adequately describe the settling velocity characteristics, based on the shape of the underlying basic settling velocity characteristic, which is used to predict the dynamics of sediment deposition. The effect on the solution of observed structural breakdown in soil aggregation due to rainfall impact was investigated, leading to more accurate predictions of the settling velocity characteristics of eroded sediment. Other sources of discrepancy between theory and observation remain to be determined.     

提高卫星遥感资料利用率的方法

从NOAA及EOS／MODIS资料的几何精校正、云检测与合成滤云、数据融合等方面分析了提高遥感资料利用率的几种有效的方法。     

阿深高速公路湖北省南段控制基准检测与精度分析

介绍了阿深高速公路湖北省南段控制网基准检测的外业实施和数据处理与分析,并用F检验方法对原测量成果和检测成果差异进行了显著性检验,得出了一些建议和结论。     

1：50万数字航空图质量检查软件设计

1：50万数字航空图生产及建库已全面启动。本文介绍了航空图的特点，根据生产实际重点论述了数字航空图质量检查软件MapCheck50的设计原理、采用的技术方法。     

广义点摄影测量及其应用

将传统的点摄影测量与当代发展的线摄影测量以及无穷远点理论综合升华为广义点摄影测量理论。论述了广义点摄影测量理论。介绍了其应用。包括由灭点计算影像参数及单像建模。由矢量与影像的匹配确定影像的参数，钣金件的检测与由轮廓线匹配确定飞机的姿态等。     

AN ANALYTICAL ONE-DIMENSIONAL MODEL OF MOMENTUM TRANSFER BY VEGETATION OF ARBITRARY STRUCTURE

An analyticalone-dimensional model of momentum transferby vegetation with variable foliage distribution,sheltering and drag coefficientis developed. The model relies on a simpleparameterization of the ratio of theabove-canopy friction velocity, u*, to thewind speed at the top of the canopy,u(h), to predict vegetation roughness length(z0) and displacement height(d) as functions of canopy height (h) and dragarea index. Model predictionsof d/h and z/h compare very favorably withobserved values.A model sensitivity analysis suggests that shelteringeffects for momentum transfertend to make canopies with non-uniform foliagedistribution resemble canopies withmore uniform foliage distribution and that anyinfluence wind speed has on d/hand z0/h is more likely to be related to theinfluence that wind speed may haveon u*/u(h) rather than the influence windspeed may have on the foliage dragcoefficient. Model results indicate that z0/hand d/h are sensitive to uncertaintiesin the numerical values of the model parameters,foliage density and distribution,sheltering effects and variations in drag coefficientwithin the canopy. In additionz0/h is also shown to be sensitive to thepresence or absence of the roughnesssublayer. Given the simplicity of the model it issuggested that it may be of usefor land surface parameterizations in large scalemodels.     

桩基质量分析及动力检测方法研究

本文分析了两类常见的沉管灌注桩和人工挖孔灌注桩的工艺特点，桩基质量问题的产生原因及动力检测方法，同要准确地判断两类桩基质量问题，必须准确计算缺陷的位置，对桩基的工艺特点和施工过程有深刻的认识，对动力检测理论有透彻的理解。同时，对人工挖孔灌注桩动力检测的特殊性进行了专门分析。     

Parachute-assisted gravity sediment corer (Algonquin Corer)

Details are outlined for the construction and use of an easily constructed and inexpensive parachute-assisted, gravity-driven, sediment coring device. This corer has been named the Algonquin corer since it was designed, tested and constructed at École Secondaire Algonquin, North Bay, Ontario. This corer utilizes an underwater parachute to effectively control and stabilize its descent, and a driving mechanism (hammer) to increase the penetration of the corer. Other innovative features are its corrective mercury and magnetic switches, which allow the user to precisely monitor both the position of the driving mechanism and the corer's angle of sediment penetration. These optional features may be constructed for use with this particular corer or constructed separately to enhance existing coring devices. Details of these features are provided and their functions outlined. The versatile features, cost-effectiveness and ease of construction of the Algonquin corer make it an effective and practical tool for conducting sediment analysis studies at all levels. It is also well suited for the instruction of coring techniques and paleolimnological methods at both the university and high school level.     

宗地识别原理

借助图论知识论述了宗地的组成及分离原理,并给出了宗地自动识别递归算法。     

自组织学习联想神经树在多金属成矿预测中的应用

本文运用自组织学习联想神经树，对鄂东南地区４４个铁帽进行了计算机识别，识别成功率达１００％，结果表明，该方法性能良好，可望成为多金属成矿预测的一种有效的辅助手段。