面向多分辨率DEM的河网相似性测度与分析

河网是地形结构的核心要素,能够有效地反映DEM对地表形态的刻画能力.实现不同分辨率条件下DEM河网相似性测度对DEM地形综合、DEM质量评估及DEM不确定性分析等研究具有重要意义.基于此,本文以黄土高原典型样区为研究区,基于5 m高精度DEM建立的多分辨率DEM数据集,构建了地形特征自适应的DEM河网自动提取方法,建立...     

机械光栅式测缝计应用于无砟轨道板上拱监测的可行性分析

高速铁路轨道的稳定性和平顺性是高速铁路正常运营的关键,因此对运营期高速铁路的轨下结构持续地开展变形监测是十分必要的。当前我国对轨道板变形的检测主要是依靠人工肉眼观察式的现场检查和常规水准测量方式进行监测,效率低下,难以在有限的天窗时间内完成辖区内轨道结构的全覆盖检测。基于此,从理论分析和实验测试两方面探讨机械光栅式测缝计应用于无砟轨道板上拱自动化监测的可行性,结果表明机械光栅式测缝计能够抵抗高温、淋水和振动等不良条件的影响,满足轨道板上拱监测的精度要求。     

巩乃斯避暑旅游气象指数分析与评价

根据巩乃斯、和静站2009—2018年6—8月的逐日平均气温、最高气温、相对湿度、风速等气象观测资料,采用对比分析、通径分析及模糊综合评价等方法对巩乃斯地区夏季避暑旅游气象资源优势进行分析和评价.结果表明:巩乃斯夏季气候凉爽、湿度适宜、风速不大,人体感觉凉爽、舒适,适合避暑旅行.人体舒适度与空气温度呈显著正相关,与相对...     

Particle manifold method (PMM): A new continuum‐discontinuum numerical model for geomechanics

Particle manifold method (PMM) is a new extension of the numerical manifold method (NMM). PMM uses a mathematical cover system to describe the motion and deformation of a particle‐based physical domain. By introducing the concept of particle into NMM, PMM takes the advantages of easy topological and contact operations with particles. In this article, the methodology, formulations and implementation of the method are presented, together with modelling examples for validation. It is found that good solutions for both continuous and discontinuous problems are obtained by the new developed PMM. Due to the underlying coupled continuum‐discontinuum property of PMM, it has great potential for modelling of geomechanical problems. Copyright © 2012 John Wiley & Sons, Ltd.     

Fuzzy Optimization Neural Network Approach for Ice Forecast in the Inner Mongolia Reach of the Yellow River/Approche d'Optimisation Floue de Réseau de Neurones pour la Prévision de la Glace Dans le Tronçon de Mongolie Intérieure du Fleuve Jaune

Abstract

In ice forecasting, a key problem is the forecast of freeze-up and break-up dates. Ice-water mechanics and the principle of heat-exchange were mainly adopted in previous research. However, the mathematical models in these studies are complex and many parameters are required in relation to upstream and/or downstream gauging stations. Moreover, too many assumptions or simplifications for these parameters and constraints directly lead to low accuracy of the models and limitations as to their practical applications. This paper develops a fuzzy optimization neural network approach for the forecast of freeze-up date and break-up date. The Inner Mongolia reach lies in the top north of the Yellow River, China. Almost every year ice floods occur because of its special geographical location, hydrometeorological conditions and river course characteristics. Therefore, it is of particular importance for ice flood prevention to forecast freeze-up date and break-up date accurately. A case study in this region shows that the proposed methodology may allow obtaining useful results.     

An integrated procedure to evaluate hydrological models

The growing concern for health‐related problems deriving from pollutants leaching is driving national and international administrations to support the development of tools for evaluating the effects of alternate management scenarios and identifying vulnerable areas. Cropping systems models are powerful tools for evaluating leachates under different environmental, social, and management conditions. As percolating water is the transport vehicle for pollutants transport in soil, a reliable evaluation of water balance models is a fundamental prerequisite for investigating pesticides and nitrate fate. As specific approaches for the evaluation of multi‐layer evolution of state variables are missing, we propose a fuzzy‐based, integrated indicator (I_SWC: 0, best; 1, worst) for a comprehensive evaluation of soil water content (SWC) simulations. We aggregated error metrics with others quantifying the homogeneity of errors across different soil layers, the capability of models to reproduce complex dynamics function of both time and soil depth, and model complexity. We tested I_SWC on a sample dataset where the models CropSyst and CERES‐Wheat were used to simulate SWC for winter wheat systems. I_SWC revealed that, in the explored conditions, the global assessment of the two models' performances allowed identification of CropSyst as the best (average I_SWC = 0·441, with a value of 0·537 obtained by CERES‐Wheat), although each model prevailed for some of the metrics. CropSyst presented the highest accuracy (average agreement module = 0·400), whereas CERES‐Wheat's accuracy was slightly worse, although achieved with a simplified modelling approach (average Akaike Information Criterion = − 230·44), thereby favouring large‐area applicability. The non‐univocal scores achieved by the models for the different metrics support the use of multi‐metric evaluation approaches for quantifying the different aspects of water balance model performances. Copyright © 2010 John Wiley & Sons, Ltd.     

梯级水库运行期设计洪水理论和方法

人类活动和气候变化显著地改变了河川径流及洪水的时空分配过程，直接影响下游断面的设计洪水。本文综述水库对下游水文情势的影响，提出梯级水库运行期设计洪水理论方法和研究内容；重点探讨非一致性洪水频率分析和基于Copula函数的最可能地区洪水组成法，比较各种方法的实用性；推荐采用运行期设计洪水及汛控水位指导水库调度运行，建议进一步加强水库运行期设计洪水计算理论和方法研究。     

Rangeland production: use of models incorporating aggregated knowledge and fuzzy construction

This work reports on a method using fuzzy membership functions to construct an aggregated interaction matrix in which the summation of variables is scaled according to the way rainfall and soil variables affect water availability to plants and hence influence rangeland productivity. Aggregation of the variables gives a comprehensive value which can be used to predict production. The model increases the predicability of production to 81% compared to models using rainfall alone and a multiplicative parametric one which give predictibilities of 61 and 76% respectively. The results showed that (1) the importance of rainfall in determining production was most important at lower rainfalls i.e. <350 mm; (2) soil texture and particularly slope were important through out the rainfall range (149–700 mm) investigated; and (3) soil depth was only important at the higher >350 mm rainfalls. The aggregated interaction matrix gives a measure of land productive capability.     

点、线符号相关处理的代数方法

本文阐述了采用地图代数的理论自动地处理各类地学信息系统编绘地图中点、线符号相关问题的技术方法——交会运算。