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911.
912.
遥感方程或大气辐射传输方程是属于第一类非线性Fredholm积分方程,这类方程的显著特征是不适定的,尤其此类问题解的不稳定性,增加了反演的难度.因此需要研究控制反演不稳定性和提高反演精度的有效方法.为了使解稳定,光滑参数γ作为约束因子是必要的.文中结合牛顿非线性迭代法反演大气廓线,利用偏差原则来最优选择光滑参数γ,即在同步反演大气廓线的同时对γ采用分步迭代的原则.最后利用中分辨率和成像光谱仪(MODIS)红外资料进行反演试验,反演结果表明采用偏差原则选取γ明显优于经验法,反演的表层温度和大气可降水量与美国国家宇航局(NASA)的MOD07产品类似. 相似文献
913.
阐述了空冷技术发展现状和开展空冷气象观测的原因,介绍了空冷气象观测站的组成、要求和观测内容,以及空冷气象参数对比分析研究的思路和方法,并对风、温度对空冷电厂的影响进行了初步分析.空冷电厂必须在厂址处建立临时气象观测站进行1 a以上的气象观测;空冷气象观测站要按标准规范建站,按电力设计的要求进行不同层次多要素的气象观测;通过厂址气象观测站和临近气象站的对比分析,重建电厂厂址近10 a的气象资料,进行分析研究得出电力设计最终所需的各种气象参数和指标;风和温度是对空冷电厂影响最大的2个气象要素. 相似文献
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916.
Climate change is putting pressure on water systems, and its effects transcend man-made boundaries, making cooperation across territorial borders essential. The governance of transboundary flood risk management calls for solidarity among riparians, as climate change will make river basins more prone to flooding. ‘Solidarity’ means that individuals act to support members of a particular community to which they belong. Recently, the solidarity principle has become institutionalized due to its formalization in the EU Floods Directive. However, it is not clear what solidarity means in the upstream–downstream practices of transboundary flood risk management. Understanding the meaning of solidarity is important for the development of cross-border climate adaptation governance. This article discusses the conceptualization of the solidarity principle and explores its meaning for international cooperation in the Dutch North Rhine–Westphalian border region. Our critical case study reveals that although all actors understand the importance of solidarity, they interpret it differently, often based on self-interest related to their position in the catchment. The formal inclusion of the solidarity principle in the Floods Directive can best be seen as a step in the continuous development of transboundary flood risk governance, as no striking changes in practice have been identified after its formalization.Policy relevanceAs climate change increasingly puts pressure on river basins and other shared resources, cross-border cooperation and solidarity are seen as increasingly important. This article discusses the meaning of solidarity in practice and reveals how this normative principle may contribute to transboundary climate adaptation governance. Understanding its meaning is important for future cross-border climate adaptation governance. 相似文献
917.
Scanning geometry: Influencing factor on the quality of terrestrial laser scanning points 总被引:1,自引:0,他引:1
Sylvie Soudarissanane Roderik LindenberghMassimo Menenti Peter Teunissen 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(4):389-399
A terrestrial laser scanner measures the distance to an object surface with a precision in the order of millimeters. The quality of the individual points in a point cloud, although directly affecting standard processing steps like point cloud registration and segmentation, is still not well understood. The quality of a scan point is influenced by four major factors: instrument mechanism, atmospheric conditions, object surface properties and scan geometry. In this paper, the influence of the scan geometry on the individual point precision or local measurement noise is considered. The local scan geometry depends on the distance and the orientation of the scanned surface, relative to the position of the scanner. The local scan geometry is parameterized by two main parameters, the range, i.e. the distance from the object to the scanner and the incidence angle, i.e. the angle between incoming laser beam and the local surface normal. In this paper, it is shown that by studying the influence of the local scan geometry on the signal to noise ratio, the dependence of the measurement noise on range and incidence angle can be successfully modeled if planar surfaces are observed. The implications of this model is demonstrated further by comparing two point clouds of a small room, obtained from two different scanner positions: a center position and a corner position. The influence of incidence angle on the noise level is quantified on scans of this room, and by moving the scanner by 2 m, it is reduced by 20%. The improvement of the standard deviation is significant, going from 3.23 to 2.55 mm. It is possible to optimize measurement setups in such a way that the measurement noise due to bad scanning geometry is minimized and therefore contribute to a more efficient acquisition of point clouds of better quality. 相似文献
918.
919.
顾及Gestalt认知效应的线性岛屿模式识别 总被引:1,自引:0,他引:1
从岛屿分布的邻近性、延展性、紧凑性、直线性等特征出发,提出了线性岛屿结构识别的新方法。首先,以Delaunay三角网为空间分析工具,计算岛屿群空间邻近关系,生成空间邻近图;然后,在空间邻近图的基础上生成MST图;最后,利用Gestalt原则对线性阵列结构的识别效应,在MST上通过3次剪枝导出线性岛屿结构。实验结果表明,该方法能够识别出具有明显线性岛屿结构的目标集,与肉眼视觉识别基本一致。 相似文献
920.
Adaptive capacity and its assessment 总被引:4,自引:0,他引:4
Nathan L. Engle 《Global Environmental Change》2011,21(2):647-656
This paper reviews the concept of adaptive capacity and various approaches to assessing it, particularly with respect to climate variability and change. I find that adaptive capacity is a relatively under-researched topic within the sustainability science and global change communities, particularly since it is uniquely positioned to improve linkages between vulnerability and resilience research. I identify opportunities for advancing the measurement and characterization of adaptive capacity by combining insights from both vulnerability and resilience frameworks, and I suggest several assessment approaches for possible future development that draw from both frameworks and focus on analyzing the governance, institutions, and management that have helped foster adaptive capacity in light of recent climatic events. 相似文献