长江上游输沙尺度效应研究

利用长江上游DEM、降雨、土地利用、土壤类型数据库,计算出通用土壤流失方程中代表影响侵蚀产沙的各因子,建立这些因子以及流域面积与长江上游268个水文站以上流域输沙模数回归关系,探讨上游侵蚀输沙的尺度效应。结果显示长江上游输沙模数与流域面积之间呈负幂函数单元回归关系,而且这一关系主要产生于降雨侵蚀力因子和土壤可蚀性因子随流域面积的变化。长江上游输沙模数随流域面积增大而降低主要发生在大约1×10⁴~1.58×10⁵km²之间。在考虑了影响侵蚀产沙因子对输沙模数的作用后,输沙模数与流域面积之间呈正幂函数相关,反映出上游输沙近源沉积的特征。分析还发现长江上游各主要支流输沙模数变化与流域尺度大小的关系和原因有明显不同。     

自动气象站现场校准过程处理经验

结合鹿寨县气象局2013年自动气象站现场校准过程实例,从自动气象站现场校准前的准备工作、正点地面观测数据维护处理、自动气象站现场校准后续工作三个方面记录分析国家一般气象站地面测报员如何配合现场校准、如何处理现场校准期间异常数据,确保数据上传质量.     

真实和有效叶面积指数及聚集指数的尺度效应

尺度效应是地球科学和定量遥感中的重要研究课题,目前的许多研究大多集中在估算尺度效应带来的误差,而对一些关键的植被结构参数是否存在尺度效应及其尺度转换方法尚存在诸多不同见解.本文针对真实和有效叶面积指数(LeafAr-ea Index,LAI和Effective LAI,LAIe)以及聚集指数(Clumping Inde...     

自动观测与人工观测数据差异的初步分析

利用2004—2007年内蒙古地区50个地面自动气象站与人工平行观测期间的数据,对自动与人工观测的气温、相对湿度、地表温度进行了差异分析,统计了两种观测之间的对比差值。对各要素观测差异在全区的分布特点进行了分析。结果表明:自动观测与人工观测各气象要素均存在一定的差异,但大部分地区各要素的差异都在自动站误差允许范围之内;造成差异的原因是多方面的,包括仪器本身存在缺陷及观测方法不一致等。     

Surveying and modeling of rock discontinuities by terrestrial laser scanning and photogrammetry: Semi-automatic approaches for linear outcrop inspection

Rock face diagnosis is a monitoring operation that is used to optimize rock-risk treatment works in terms of ensuring that safety requirements are met at the lowest cost. Diagnoses require measuring the location and orientation of rock discontinuities at the surface of the rock mass. These measurements are then entered into a structural model that extrapolates the data collected at the surface to the inner part of the rock mass. Currently, most surveys are empirical and are carried out manually using a compass-clinometer. In addition, they tend to examine only the most highly fractured area of a rock face, even though safety considerations demand an exhaustive study of the whole face. These deficiencies can be overcome by using dense 3D measurement techniques such as terrestrial laser scanning and optical imaging to obtain a more complete 3D model and structural statement. Hence, we have developed a semi-automatic process that allows 3D models to be combined with the results of field surveys in order to provide more precise analyses of rock faces, for example, by classifying rock discontinuities into subsets according to their orientation. Further research is being carried out in order to combine 3D data and 2D digital images as a support for structural survey. Trials carried out in a limestone quarry in the French Alps allowed us to compare data sets obtained using manual surveying methods, the well-known laser scanning method and the lower-cost photogrammetric survey method.     

守时系统故障实时诊断

对守时系统故障诊断的基本思想作了阐述,重点介绍了基于VB 6.0开发的守时系统故障自检软件,该软件具有可视化、自动化、智能化等特点.采用类似示波器的图形绘制方法,可以实时显示国家授时中心(NTSC)的时间基准实验室中各钟、授时部工作钟和BPL长波授时信号与NTSC主钟(MC)的比对结果的数据曲线,并对守时系统出现的各种故障,代替维护人员完成异常分析、故障诊断和故障定位任务,自动给出实时的诊断结果,为守时系统故障的快速修复提供依据.     

Catchment transit times and landscape controls—does scale matter?

Mean transit times (MTTs) can give useful insights into the internal processes of hydrological systems. However, our understanding of how they vary and scale remains unclear. We used MTT estimates obtained from δ¹⁸O data from 20, mostly nested, contrasting catchments in North East Scotland, ranging from 1 to 1700 km². The estimated MTTs ranged between 270 and 1170 days and were used to test a previously developed multiple linear regression (MLR) model for MTT prediction based on metrics of soil cover, landscape organization and climate. We show that the controls on MTT identified by the MLR model hold with the independent data from these 20 sites and that the MLR can be used to predict MTT in ungauged montane catchments. The dominant controls also remain unchanged over four orders of magnitude of catchment size, suggesting no major change of dominant flow paths and mixing processes at larger scales. This is consistent with the fact that only the variance of MTT, rather than MTT, showed a scaling relationship. MTTs appeared to converge with increasing catchment scale, apparently due to the integration of heterogeneous headwater responses in larger downstream catchments. Copyright © 2009 John Wiley & Sons, Ltd.     

桩靴连续贯入过程的动态模拟方法研究

采用CEL方法(耦合的欧拉-拉格朗日分析法)对比研究桩靴下沉速度不同对计算结果的影响,分析不同桩靴下沉速度下附近桩基础的响应,研究质量放大方法的适用性。结果表明:无桩时桩靴贯入速度不同对土体阻力影响较小,土体的破坏形态和剪应力水平略有不同;桩靴贯入速度对桩身水平位移影响较小,桩靴贯入速度越大,桩身最大应力越小;质量放大系数的增加对桩身最大位移的影响较小,但对桩身最大应力有较大影响,因此建议谨慎使用质量放大方法。     

Sensitivity analysis of hydraulic conductivity and Manning's n parameters lead to new method to scale effective hydraulic conductivity across model resolutions

Hydrological modelling is an important tool for research, policy, and management, but uncertainty remains about parameters transferability from field observations made at small scale to models at the catchment scale and larger. This uncertainty compels the need to develop parameter relationships that are translatable across scale. In this study, we compare the changes to modelled processes as resolution is coarsened from 100‐m to 1‐km in a topographically complex, 255‐km² Colorado River headwater catchment. We conducted a sensitivity analysis for hydraulic conductivity (K) and Manning's n parameters across four orders of magnitude. Results showed that K acts as a moderator between surface and subsurface contributions to streamflow, whereas n moderates the duration of high intensity, infiltration‐excess flow. The parametric sensitivity analysis informed development of a new method to scale effective hydraulic conductivity across modelling resolutions in order to compensate for the loss of topographic gradients as resolution is coarsened. A similar mathematical relationship between n and lateral resolution changes was not found, possibly because n is also sensitive to time discretization. This research provides an approach to translate hydraulic conductivity parameters from a calibrated coarse model to higher resolutions where the number of simulations are limited by computational demand.     

基于车辆导航的路径分析与应用

在目前前的车辆自导航系统（VANS）中,普遍存在着路径分析功能不强的问题,本文围绕这个问题,从其相关技术方面进行了研究,并通过实例进行了验证。