基于GIS和RS的蓄滞洪区和谐发展的技术路线

应用遥感与地理信息系统技术构建基于GIS模型的蓄滞洪区空间数据库,对蓄滞洪区内的基础地理数据进行存储、管理,并对空间数据进行可视化和空间分析等操作;运用RS技术对蓄滞洪区内的土地利用、生态环境变化等情况进行动态监测,建立蓄滞洪区发展指标体系;探求蓄滞洪区的和谐发展模式,为蓄滞洪区的可持续发展提供科学依据。     

A model of West African millet prices in rural markets

In this article we specify a model of millet prices in the three West African countries of Burkina Faso, Mali, and Niger. Using data obtained from USAID’s Famine Early Warning Systems Network (FEWS NET) we present a unique regional millet price forecasting model that takes advantage of the panel nature of our data and accounts for the distance of rural markets from capital cities. Another novel aspect of our analysis is our use of the Normalized Difference Vegetation Index (NDVI) to detect and control for variation in conditions for productivity. We find that including NDVI information significantly improves price forecasts.     

基于多源数据融合的地表覆盖数据重建研究进展综述

地表覆盖数据对于全球环境变化、生物多样性和发展政策制定有着重要意义。遥感已成为获取地表覆盖数据的重要手段。而目前的地表覆盖数据产品,如Globe Land30、FROM-GLC、MODIS Collection5、MODIS Cropland、Glob Cover、GLC2000等,存在数据精度不高、数据间一致性较差、与统计数据差异较大等问题。因此,基于多源数据融合的数据重建方法成为目前研究中的热点问题。文章检索了近10年关于多源数据融合在地表覆盖数据重建中的应用的相关文献,概括了多源数据在数据重建中的应用现状,并对基于多源数据融合的地表覆盖数据重建方法进行了归纳总结,重点评述了不同方法的特点及应用情况,阐明了各种方法的优势与不足,同时对存在的问题进行探讨并展望了未来基于多源数据融合的地表覆盖数据重建研究的发展方向。基于多源数据融合的数据重建方法包括基于多源遥感数据融合法以及基于多源遥感和非遥感数据融合法。该文在对基于多源遥感数据融合的数据重建方法进行论述时,主要讨论了其中应用最广泛的两种融合方法:基于数据一致性的融合法和基于回归分析的融合法。对于其他基于多源遥感数据融合的数据重建方法,如基于D-S证据理论融合法、基于数据集成融合法、基于统计模型融合法,也列举了最具代表性的相关文献进行论述。在对基于遥感数据和非遥感数据融合的数据重建方法进行论述时,主要讨论了其3种空间分配方法:完全依赖法、部分依赖法、动态依赖法。在对目前研究进行探讨的过程中,该文对其研究区域、数据源、地表覆盖类型、空间分辨率、融合方法和文献来源进行总结分析,并重点就融合方法展开讨论。围绕各种融合方法在数据重建中的运用,该文归纳出目前研究中存在的主要问题:研究对象和区域上的不足,研究区多为全球及欧美,其他区域的研究过少,研究对象多为所有地表覆盖类型和森林,对耕地和草地的研究过少;融合算法上的不足、重建结果精度上的不足。最后,指出基于多源数据融合的数据重建方法未来的发展方向,即综合运用两类方法,得到具有详细完整空间信息的长时间序列的地表覆盖数据集。     

城市三维形态与热环境的相关关系研究——以大连市金普新区为例

由城市各种实体空间结构所构成的三维形态是城市形态的重要组成部分。而城市的空间结构与城市空间环境的热场分布也有着密不可分的关系。本文运用地理信息系统与遥感技术,获取三维形态指标与地表温度,对各因子进行回归分析,建立城市空间形态热场分布研究的回归模型。分析了金普新区空间实体的占空度、错落度、建筑密度等空间形态对城市亮度温度的影响,发现占空度与城市亮温成正相关并且相关性较高,绿化率与亮温成负相关,而建筑密度与错落度对城市热场的影响较小。     

Implications of land use transitions on soil nitrogen in dynamic landscapes in Tanzania

Land use transitions are rated among the leading sources of greenhouse gas emissions in the tropics. They significantly challenge the functioning of ecosystems and affect multi-temporal stability of greenhouse gases such as N₂O and soil properties. Studies on dynamics in nitrogen balances are essential in understanding greenhouse gas emissions such as N₂O and to manage their impacts on productivity. In this study, multi-temporal Landsat images (1975, 1995 and 2012) were classified to determine land use transitions and potential drivers. The classified images were categorized into degraded and non-degraded lands and eighty sampling plots generated within the entire study area. Soil samples were then collected at 0–15, 15–30 and 30–60 cm depths on each plot and soil nitrogen determined. A regression analysis was developed to determine the influence of forest and grassland degradation on soil nitrogen. Results indicated a significant change in major land use and land cover types. Specifically, there was a decrease in areas covered by forests, woodland and grassland, however, area covered by less dense forest increased. Results also indicated variability in mean nitrogen content between degraded and non-degraded areas and depths. Furthermore, levels of degradation influence nitrogen content up to a soil depth of 30 cm. The present study is relevant in the detailed assessment of the extent of damage and threats posed to biodiversity hotspots in sub-Saharan Africa. These results are transferable to other parts of the world characterized by dynamic ecological transformation.     

黑土典型区有机质高光谱预测模型

土壤有机质(SOM)是鉴别土壤肥力的重要指标,是土壤肥力的物质基础,其含量预测模型研究对于土壤肥力评价、土壤碳库估算、土壤资源利用与保护具有重要意义。该文以黑龙江省黑土带典型区为例,采集区域土壤样本,基于有机质含量与土壤反射率的定量关系,对光谱反射率进行一阶微分和倒对数的处理,建立偏最小二乘法模型(PLSR)、一元线性回归模型和多元线性逐步回归模型。结果表明:(1)土壤有机质敏感波段位于650-750nm。(2)通过比较建模样本与检验样本的决定系数(R2)和均方根误差(RMSE)的大小,得到反射率和倒对数处理后的数据最优模型都为PLSR模型,一阶微分处理后的最优模型为多元线性逐步回归模型。(3)PLSR模型的建模效果优于回归模型,但其预测效果却并不理想。该研究将为改进土壤理化参数、遥感反演、土地质量评价等工作方法提供理论与技术支持。     

Urban Sensing by Crowdsourcing: Analysing Urban Trip behaviour in Zurich

The research on which this essay is based sought to provide a deeper understanding of live urban activities. The main idea was to obtain in‐depth trip information by integrating sensing technology with crowdsourcing‐based methods. Location and acceleration sensors embedded in smartphones can deliver useful trip information. Research had previously been conducted to find an accurate data analysis algorithm for high‐level data mining, an efficient sensing method for power saving. As a proof of concept, this essay presents a case study of Zurich that successfully implemented previous research achievements in the real environment. It established that urban travel behaviour can, in fact, be collected by sensors embedded in mobile devices, and that the data thus obtained can be used to measure the characteristics of trip behaviour in cities by means of an advanced classifying algorithm and analysis. The strength of this research is its pioneering role in clearing the ground for future urban data collection methods and planning strategies. Specifically, this study could provide answers to the following key questions: How can crowdsourcing be applied to the collection of urban transportation data? What kinds of information can be extracted from the crowdsourced mobile sensing platform? What kinds of knowledge, within the transportation domain, can be derived from the above?     

农业水循环与水环境遥感应用研究进展

农业生产受环境因素影响大,进入农耕文明以来,农业对气候的高度依赖局面没有得到根本性的改变,频繁的自然灾害给我国的农村经济发展造成了极大的困难。遥感技术是运用各类非接触的主被动的探测设备,对地面目标物的电磁波辐射与反射特性进行探测,通过其特性分析,探明其物体性质、特征及状态的综合性探测技术。它具有覆盖面积广、空间分辨率高、获取信息大、重访周期短等优点,适用于农业资源调查与自然灾害监测等农业相关领域的研究,对农业生产的指导与相关部门的决策管理意义重大。文章主要针对国内遥感技术在农业水循环与水环境的发展、应用现状进行综述与分析,并对遥感技术在农业水资源领域的发展趋势进行展望。     

基于光谱吸收的光纤瓦斯气体传感系统分析

根据瓦斯气体在一定波段对光有吸收的特性,通过对煤矿瓦斯气体吸收光谱的分析,研究了一种光纤传感瓦斯气体系统。     

污染地域环境水文地质勘查技术应用浅探

随着时代的发展,科技水平的不断进步,社会对水文地质勘察技术的关注程度越来越高,其应用范围也越来越广。