像方和物方结合的线阵卫星核线影像生成方法

针对线阵卫星影像核线纠正问题,本文简要分析了现有方法的优劣势,并在此基础上提出一种将基于像方和物方相结合的核线纠正方法。其分为两步：首先在影像空间内对左影像进行分块并逐区域纠正,利用局部仿射拟合的方法实现左影像的核线纠正;然后利用物方投影基准面生成与左影像分辨率一致的右核线影像。试验结果表明,本文方法既能获取上下视差接近于零且优于对比方法的核线影像产品,又能够保证核线影像左右视差与高程的线性比例关系,尤其是3组较大核线曲率数据试验结果,证实了本文方法具有较好的稳健性和适用性,能够较好地应用到不同传感器的数据处理系统中。     

基于无人机影像密集匹配点云的传统村落地面点提取及DEM生成——以湘西德夯村为例

目前,针对利用无人机技术在山地起伏大、山体植被密集区域,难以获取地面点及DEM等问题,本文提出了一种结合布料模拟算法和改进的局部最大值算法,利用树顶点、树高等植被信息,提取地面点,进而生成整个区域的DEM的方法。以中国传统村落德夯村为例,利用植被系数和高程信息将点云分割为植被密集区和非植被密集区两个部分。在非植被密集区,通过布料模拟算法和改进的局部最大值算法分别提取地面点和树顶点,计算平均树高;在植被密集区,通过该区域的树顶点推算得到植被密集区的近似地面点,最终将两部分的地面点云进行TIN插值得到该地区的DEM。试验结果表明,利用此方法生成的DEM均方根误差,在非植被密集区达0.037 m,植被密集区可达1.606 m,整体平均误差达1.492 m,总体精度较好,基本可以满足村落尺度空间分析的需求。     

Determination of the Backward Predictability Limit and Its Relationship with the Forward Predictability Limit

In this work, two types of predictability are proposed—forward and backward predictability—and then applied in the nonlinear local Lyapunov exponent approach to the Lorenz63 and Lorenz96 models to quantitatively estimate the local forward and backward predictability limits of states in phase space. The forward predictability mainly focuses on the forward evolution of initial errors superposed on the initial state over time, while the backward predictability is mainly concerned with when the given state can be predicted before this state happens. From the results, there is a negative correlation between the local forward and backward predictability limits. That is, the forward predictability limits are higher when the backward predictability limits are lower, and vice versa. We also find that the sum of forward and backward predictability limits of each state tends to fluctuate around the average value of sums of the forward and backward predictability limits of sufficient states.Furthermore, the average value is constant when the states are sufficient. For different chaotic systems, the average value is dependent on the chaotic systems and more complex chaotic systems get a lower average value. For a single chaotic system,the average value depends on the magnitude of initial perturbations. The average values decrease as the magnitudes of initial perturbations increase.     

基于RMAPS的一次局地强降水过程成因分析

2017年8月8日午夜,天津北辰区出现局地短时强降水,小时雨强超过70mm·h~(-1)。利用RMAPS(Rapidrefresh Multi-scale Analysis and Prediction System)和观测资料,通过多种资料叠加、雷达回波参数量化和低层风场反演等方法分析了降水成因,结果表明:①降水是由M_βCS(Meso-β-scale Convective System)后向传播过程中尾部的多单体雷暴造成的,传播过程中单体合并对雷暴系统的结构及增强有重要影响,合并后系统的回波体积参数V_(40)(反射率≥40dBz的体积)增长了23.3%,在V_(40)增长之前,变率参数F_(V40-up6)(6km以上40dBz回波体积6min的变化)出现了"突降",这对雷暴系统即将发展有预警意义;②冷池出流与地面东南风形成的辐合线是对流系统维持的关键,中低层切变线也为对流的发生发展提供了有利的动力条件;伴随着强降水,对流有效位能CAPE由峰值急速下降,低层垂直风切变指数α骤增,这揭示了不稳定能量、垂直风切变与对流过程之间的关系;③降水落区与不稳定参数SWEAT的大值区对应,预警时间3h,来自渤海的地面暖湿带与假相当位温密集带的交汇处也是落区临近预报的关注点。     

Power interplay between actors: using material and ideational resources to shape local adaptation plans of action (LAPAs) in Nepal

Deliberation over how to adapt to short or long-term impacts of climate change takes place in a complex political setting, where actors’ interests and priorities shape the temporal dimension of adaptation plans, policies and actions. As actors interact to pursue their individual or collective interests, these struggles turn into dynamic power interplay. In this article, we aim to show how power interplay shapes local adaptation plans of action (LAPAs) in Nepal to be short-term and reactive. We use an interactional framing approach through interaction analyses and observations to analyse how actors use material and ideational resources to pursue their interests. Material and ideational resources that an actor deploys include political authority, knowledge of adaptation science and national/local policy-making processes, financial resources and strong relations with international non-governmental organizations and donor agencies. We find that facilitators and local politicians have a very prominent role in meetings relating to LAPAs, resulting in short-termism of LAPAs. Findings suggest that there is also a lack of female participation contributing to short-term orientated plans. We conclude that such power interplay analysis can help to investigate how decision making on the temporal aspects of climate adaptation policy takes place at the local level.

Key policy insights

• Short-termism of LAPAs is attributed to the power interplay between actors during the policy design process.

• Improved participation of the most vulnerable, especially women, can lead to the preparation of adaptation plans and strategies focusing on both the short and long-term.

• It is pertinent to consider power interplay in the design and planning of adaptation policy in order to create a level-playing field between actors for inclusive decision-making.

• Analysis of dynamic power interplay can help in investigating climate change adaptation controversies that are marked by uncertainties and ambiguities.

     

中国地区城市热岛环流研究进展

城市热岛环流是由城市热岛激发的、存在于边界层的局地环流。这一环流常影响城市区域污染物的扩散及城市降水,是城市气象学的重点研究对象。在过去30多年间,中国城市热岛环流的研究不断取得突破,研究成果丰富。为了今后更有效地开展相关研究,本文从观测分析、理论与数值模拟研究两方面,回顾并总结了我国在热岛环流研究方面取得的成果,包括热岛环流的时空特征、产生机制,以及热岛环流与其他局地环流的相互作用。此外,本文总结了热岛环流对城市及其周边地区污染物水平和垂直分布的影响。     

车载激光扫描数据的结构化道路要素自动提取方法

道路识别是无人驾驶、机器导航等领域的关键问题之一。本文利用局部特征约束方法进行点云的预处理分割,基于多尺度聚类方法实现道路要素的点云提取,并在结构化道路实例的识别中进行应用。结果表明,该方法效果良好,是一种合理有效的道路识别手段。     

甘肃省地方标准“绿色矿山建设规范”编制说明

论述了甘肃省地方标准《绿色矿山建设规范》（煤矿、金属矿、非金属矿、石油天然气、砂石粘土矿5个部分）的编制背景、编制过程、编制原则、主要内容、主要特点、使用《规范》的几点说明。重点从基本条件、资源开发利用、节能减排、科技创新与智能化建设、矿区环境、企业管理与企业形象等绿色矿山建设的6个主要方面进行简要论述;与行业标准进行对比分析,总结《规范》的共性特点和各部分特点。     

知识异质性视角下的地方产业演化理论前沿研究

地方产业演化是在全球化和知识经济背景下地方参与全球分工、累积地方性知识并获取价值的过程。知识是演化理论研究的核心,但是对于产业演化过程中涉及到多种类型的知识及其在演化过程中的地位和作用目前缺乏系统研究。为了深化对地方产业演化路径的认知,基于知识异质性视角对地方产业在全球化背景下演化的相关研究进行梳理和归纳。地方产业演化理论建设中,知识异质性是研究的基础,知识关系是研究的核心领域,知识异质性具有空间尺度。演化理论地方化的前沿研究领域主要集中于知识的地方化、知识异质性的测度、开放环境下的地方产业演化路径比较研究、地方产业演化的知识动力研究、演化的方法与工具的创新等方面。理论前沿的研究有助于指导分析地方产业演化基础、方向与动力,将促进地方产业发展从"基于资源的发展观"向"基于知识的发展观"转变,为改变产业增长方式提供基础理论支撑。     

一种基于局部曲率特征的点云精简算法

平均曲率是分析三维表面的重要几何特征之一。根据平均曲率进行海量散乱点云数据的精简,首先通过空间包围盒法建立K邻域,然后对K邻域内的点拟合二次曲面计算平均曲率,最后以邻近区域内点的平均曲率中误差为阈值,结合点的精简概率判定点是否保留。通过与传统方法对比,证实了文中方法在保留特征点和压缩上具有较好的优势。