华北陆块东南缘凤台组时代的讨论

华北陆块东南缘凤台组归属于震旦系或寒武系尚无定论,影响了对华北陆块震旦纪与寒武纪转折时期的古构造、古地理和古生物的重大质变事件的探讨。本文根据下震旦统顶部与凤台组之间裂离不整合的发现及其意义的讨论,以及凤台组夹层粉砂质泥岩620Ma的Pb-Pb等时线年龄,基本厘定出凤台组时代为晚震旦世。     

青海高原近43年夏季水汽分布及演变特征

通过对青海高原近43年夏季空中水汽分布及演变的研究,结果表明:(1)夏季来自孟加拉湾的暖湿水汽在东亚夏季风的驱动下向东北方向输送,与沿中纬度的西风环流输送的水汽在青海高原会合,但受高原大地形阻挡,到达该区的水汽含量较源区大大减小;(2)青海高原水汽通量场自西界向东界增加,水汽通量高值区基本分布在青海东部的边坡地带;(3)近43年青海高原净水汽通量收支有正有负,但整体上却呈增加趋势;(4)旱年青海高原水汽通量比平均状况偏少10~40 kg.m-1.s-1;涝年偏多10~20 kg.m-1.s-1;无论旱涝年,青海高原空中净水汽通量均呈正值,但旱年比平均状况偏少21.88%,涝年偏多53.99%。     

与澜沧大震可能相关的震磁效应——小波分析一例

用小波法分析了与1988年澜沧大震相关的通海台地磁Z分量资料。小波分析结果显示地震前“日变幅差”ΔTg(24)存在可能的异常变化;异常为正异常,异常幅度很大,异常结束后立即发生了地震。     

水准测量野外数据处理采用手机取代PC1500的研究

通过易县地震台水准数据处理手机程序的设计,研究了用手机取代PC1500的可行性。结果表明,用手机取代PC1500,进行水准数据的存储计算是完全可行的。     

“一带一路”建设背景下重庆与东盟国家贸易格局演变和影响因素分析

“贸易畅通”是“一带一路”建设的重要内容,重庆作为中国西部地区内陆开放高地,贸易发展优势明显。运用贸易强度指数和HM指数,分析2001—2017年重庆与东盟国家贸易格局和贸易依赖程度,并分析影响重庆与东盟国家贸易格局的影响因素。结果表明：①重庆与东盟国家贸易联系紧密,增长速度快,贸易总额在“一带一路”沿线六大区域中始终保持领先地位;②马来西亚和泰国成为重庆与东盟国家中最重要的贸易伙伴,越南、新加坡、菲律宾和印度尼西亚紧随其后,而与缅甸、柬埔寨、老挝和文莱的贸易总额较少;③在进口方面,形成以马来西亚、泰国和越南为首的多元进口格局,泰国和越南进口伙伴地位上升。在出口方面,形成以马来西亚为首的多元出口新格局,越南出口地位下降;④在市场相互依赖程度方面,重庆出口对东盟国家特别是马来西亚和新加坡贸易市场的重要性程度上升,而对东盟国家市场依赖程度较小;⑤产业结构、贸易通道、文化交流和政策等是影响重庆与东盟国家贸易格局的重要影响因素。     

Tree species identification within an extensive forest area with diverse management regimes using airborne hyperspectral data

Information on tree species composition is crucial in forest management and can be obtained using remote sensing. While the topic has been addressed frequently over the last years, the remote sensing-based identification of tree species across wide and complex forest areas is still sparse in the literature. Our study presents a tree species classification of a large fraction of the Białowieża Forest in Poland covering 62 000 ha and being subject to diverse management regimes. Key objectives were to obtain an accurate tree species map and to examine if the prevalent management strategy influences the classification results. Tree species classification was conducted based on airborne hyperspectral HySpex data. We applied an iterative Support Vector Machine classification and obtained a thematic map of 7 individual tree species (birch, oak, hornbeam, lime, alder, pine, spruce) and an additional class containing other broadleaves. Generally, the more heterogeneous the area was, the more errors we observed in the classification results. Managed forests were classified more accurately than reserves. Our findings indicate that mapping dominant tree species with airborne hyperspectral data can be accomplished also over large areas and that forest management and its effects on forest structure has an influence on classification accuracies and should be actively considered when progressing towards operational mapping of tree species composition.     

Lidar-aided analysis of boreal forest backscatter at Ku band

This paper analyzes the backscatter of the microwave signal in a boreal forest environment based on a Ku -band airborne Frequency-Modulated Continuous Waveform (FMCW) profiling radar—Tomoradar. We selected a half-managed boreal forest in the southern part of Finland for a field test. By decomposing the waveform collected by the Tomoradar, the vertical canopy structure was achieved. Based on the amplitude of the waveform, the Backscattered Energy Ratio of Canopy-to-Total (BERCT) was calculated. Meanwhile, the canopy fraction was derived from the corresponding point cloud recorded by a Velodyne VLP-16 LiDAR mounted on the same platform. Lidar-derived canopy fraction was obtained by counting the number of the first/ the strongest returns versus the total amount of returns. Qualitative and quantitative analysis of radar-derived BERCT on lidar-derived canopy fraction and canopy height are investigated. A fitted model is derived to describe the Ku-band microwave backscatter in the boreal forest to numerically analyze the proportion contributed by four factors: lidar-derived canopy fraction, radar-derived canopy height, the radar-derived distance between trees and radar sensor and other factors, from co-polarization Tomoradar measurements. The Root Mean Squared Error (RMSE) of the proposed model was 0.0958, and the coefficient of determination R2 was 0.912. The fitted model reveals that the correlation coefficient between radar-derived BERCT and lidar-derived canopy fraction is 0.84, which illustrates that lidar surface reflection explains the majority of the profiling /waveform radar response. Thus, vertical canopy structure derived from lidar can be used for the benefit of radar analysis.     

利用水准数据的天津市地面沉降时空特征分析

地面不均匀沉降可能对城市的发展与人民的安全造成危害,天津市的地面沉降情况尤为严重。针对该问题,本文收集天津市2005—2012年、2016—2017年水准观测数据,以固定水准点位的沉降量、沉降速率、沉降加速率为状态向量,构建卡尔曼滤波模型,对天津市历年的水准观测数据进行滤波;根据滤波后的结果,本文利用多项式加权内插的方法,以距离、沉降速率、沉降加速率信息确定权值大小,对地面沉降情况进行内插;并以中误差作为精度评定参数,比较多种内插方法的精度。通过对内插结果的试验分析发现,2005—2017年天津市地面累计平均沉降量为394.477 5 mm,最大沉降量为1 143.5 mm;主要沉降区域为北辰、大港、塘沽等地区,且随着时间的增长,这些区域呈现漏斗式下沉。试验证明本文结合卡尔曼滤波与多项式加权内插的方式能够较好地反映地面沉降的时空特征分布情况并对未来一段时间的沉降情况进行预测,对天津市的城市发展及建设有一定的参考意义。     

地面沉降监测多源数据融合分析

地面沉降是区域性地面高程下降的一种地质现象,一般是由自然因素和人为因素的共同作用导致的。目前地面沉降监测的方法很多,各有优劣。本文结合武进中心城区地面沉降监测系列工程案例,对不同沉降监测方法产生的多源数据进行了分析、对比和融合,使成果兼具各种方法的优点,其不仅能更好地描述地面沉降的现状及预测地面沉降的发展趋势,而且可为后期地面沉降监测提供更加准确且丰富的数据基础。     

球面小波模型在GPS高程拟合中的应用

本文利用某地共99个GPS水准点的大地高和正常高求取高程异常,使用DOG球面小波模型和多面函数,分别对高程异常进行拟合。拟合时剔除模型残差大于2倍中误差的点,并在剔除粗差后重新进行拟合。通过比较外部检核点的已知高程异常值和球面小波模型值、多面函数拟合值之间的均方差评价模型的精度。数据结果表明,以外部检核均方差最小为准则,球面小波模型拟合精度较优,其拟合精度为1.65 cm,多面函数拟合精度为2.35 cm。