川藏铁路西藏昌都段生态保护重要性评价     

王思源  赵敏敏  闫晶  马鑫  刁玉杰  付雷  罗倩 《现代地质》2021,35(1):234-243

生态系统服务功能与生态系统敏感性是衡量生态系统质量及实现高质量生态文明建设的重要依据。川藏铁路沿途跨越多个自然地理单元,生态环境保护是铁路规划、建设及运行过程中面临的关键问题。以川藏铁路西藏昌都段为研究对象,采取资料分析与野外调查结合的手段,运用生态评价模型对研究区的生态系统服务和生态脆弱性进行分析,并基于研究结果对铁路途经区域的生态保护重要性进行评价。结果表明,当前昌都境内川藏铁路涉及的生态保护极重要区、重要区和一般重要区占比分别为42.19%、52.69% 和5.12%。评价结果有助于在铁路规划、建设及运营过程中对工程活动进行合理布局,有针对性地降低对生态系统的负面影响,达到社会经济效益和生态效益双赢的目的。  相似文献   

Response of a loess landslide to rainfall: observations from a field artificial rainfall experiment in Bailong River Basin,China     

Guan Chen  Xingmin Meng  Liang Qiao  Yi Zhang  Siyuan Wang 《Landslides》2018,15(5):895-911

Rainfall-induced landslides are a significant hazard in many areas of loess-covered terrain in Northwest China. To investigate the response of a loess landslide to rainfall, a series of artificial rainfall experiments were conducted on a natural loess slope, located in the Bailong River Basin, in southern Gansu Province. The slope was instrumented to measure surface runoff, pore water pressure, soil water content, earth pressure, displacement, and rainfall. The hydrological response was also characterized by time-lapse electrical resistivity tomography. The results show that most of the rainfall infiltrated into the loess landslide, and that the pore water pressure and water content responded rapidly to simulated rainfall events. This indicates that rainfall infiltration on the loess landslide was significantly affected by preferential flow through fissures and macropores. Different patterns of pore water pressure and water content variations were determined by the antecedent soil moisture conditions, and by the balance between water recharge and drainage in the corresponding sections. We observed three stages of changing pore water pressure and displacement within the loess landslide during the artificial rainfall events: Increases in pore water pressure initiated movement on the slope, acceleration in movement resulting in a rapid decrease in pore water pressure, and attainment of a steady state. We infer that a negative pore water pressure feedback process may have occurred in response to shear-induced dilation of material as the slope movement accelerated. The process of shear dilatant strengthening may explain the phenomenon of semi-continuous movement of the loess landslide. Shear dilatant strengthening, caused by intermittent or continuous rainfall over long periods, can occur without triggering rapid slope failure.  相似文献   

卫星导航系统地面监控站站间通信抗干扰研究     

任小伟  梁思远 《全球定位系统》2014,(3):49-52

全球卫星导航系统中,地面监测站和主控站通信传输容易受到宽带和窄带干扰的影响,导致卫星导航系统精确性和完好性降低。分析研究利用扩频增益抑制宽带干扰和利用陷波滤波器抑制窄带干扰,解决地面监测站和主控站站间通信抗宽带和窄带干扰问题,为增强卫星导航系统精确性和完好性提供了保障。  相似文献   

不同散射模式下S波包络合成          下载免费PDF全文

景月岭  何李浩  李明会  张宇璇  郑司元 《地震学报》2021,43(6):679-689

为揭示地震波在地壳小尺度非均匀介质中的散射过程,更准确地描述地震波的包络展宽现象,本文基于多次各向异性散射理论,采用离散波数法求解能量密度积分方程,选取高斯型自相关函数表征的散射模式,得到S波能量密度包络。基于此,本文首先分析了单次散射和多次散射在形成S波能量密度包络中的贡献规律;然后探讨了吸收系数和总散射系数对合成S波能量密度包络的影响;最后对比了在不同散射模式下合成的S波能量密度包络的差异。结果显示:① 不同的散射模式下单次散射和多次散射对地震波散射过程的贡献规律是一致的,对于近震（震源距小于100 km）,单次散射模型可以近似合成S波能量密度包络;随着震源距增大,多次前散射模型可以更快地接近总能量密度包络;② 吸收系数增大会降低直达S波和尾波幅值,总散射系数增大会降低直达S波幅值,但使得S波尾波幅值升高;③ 前散射模式下S波能量密度包络随震源距的增大会导致峰值延迟,包络展宽,尾波衰减一致性更快等现象产生。   相似文献   

基于三维声呐点云的河口水闸水下结构安全评估     

冯露  李艳  席思远  郑晓东 《测绘通报》2022,(1):100-104

河口水闸水下结构安全对于水闸工程、整个河道,以及周边居民地的安全具有重要意义。在低可视度的水体环境中,采用传统人工潜水探摸方式进行水下结构安全检测效率低下。为提高效率,三维扫描声呐逐步应用于相关水下结构的安全检测中。本文以BlueView BV5000型三维扫描声呐系统在苏州河河口水闸水下结构的实测数据为基础,经滤波、测站拼接等处理过程,利用所得三维声呐点云对该水闸的水下结构进行安全评估。采用人工探摸方式对评估结果进行验证,结果表明,三维扫描声呐在水下结构安全评估中具有优越性,可为后续运维保障提供数据基础。  相似文献   

Delimiting Ecological Space and Simulating Spatial-temporal Changes in Its Ecosystem Service Functions based on a Dynamic Perspective: A Case Study on Qionglai City of Sichuan Province,China     

OU Dinghua  WU Nengjun  LI Yuanxi  MA Qing  ZHENG Siyuan  LI Shiqi  YU Dongrui  TANG Haolun  GAO Xuesong 《资源与生态学报(英文版)》2022,13(6):1128-1142

Delimiting ecological space scientifically and making reasonable predictions of the spatial-temporal trend of changes in the dominant ecosystem service functions (ESFs) are the basis of constructing an ecological protection pattern of territorial space, which has important theoretical significance and application value. At present, most research on the identification, functional partitioning and pattern reconstruction of ecological space refers to the current ESFs and their structural information, which ignores the spatial-temporal dynamic nature of the comprehensive and dominant ESFs, and does not seriously consider the change simulation in the dominant ESFs of the future ecological space. This affects the rationality of constructing an ecological space protection pattern to some extent. In this study, we propose an ecological space delimitation method based on the dynamic change characteristics of the ESFs, realize the identification of the ecological space range in Qionglai City and solve the problem of ignoring the spatial-temporal changes of ESFs in current research. On this basis, we also apply the Markov-CA model to integrate the spatial-temporal change characteristics of the dominant ESFs, successfully realize the simulation of the spatial-temporal changes in the dominant ESFs in Qionglai City's ecological space in 2025, find a suitable method for simulating ecological spatial-temporal changes and also provide a basis for constructing a reasonable ecological space protection pattern. This study finds that the comprehensive quantity of ESF and its annual rate of change in Qionglai City show obvious dynamics, which confirms the necessity of considering the dynamic characteristics of ESFs when identifying ecological space. The areas of ecological space in Qionglai city represent 98307 ha by using the ecological space identification method proposed in this study, which is consistent with the ecological spatial distribution in the local ecological civilization construction plan. This confirms the reliability of the ecological space identification method based on the dynamic characteristics of the ESFs. The results also show that the dominant ESFs in Qionglai City represented strong non-stationary characteristics during 2003-2019, which showed that we should fully consider the influence of the dynamics in the dominant ESFs on the future ESF pattern during the process of constructing the ecological spatial protection pattern. The Markov-CA model realized the simulation of spatial-temporal changes in the dominant ESFs with a high precision Kappa coefficient of above 0.95, which illustrated the feasibility of using this model to simulate the future dominant ESF spatial pattern. The simulation results showed that the dominant ESFs in Qionglai will still undergo mutual conversions during 2019-2025 due to the effect of the their non-stationary nature. The ecological space will still maintain the three dominant ESFs of primary product production, climate regulation and hydrological regulation in 2025, but their areas will change to 32793 ha, 52490 ha and 13024 ha, respectively. This study can serve as a scientific reference for the delimitation of the ecological conservation redline, ecological function regionalization and the construction of an ecological spatial protection pattern.  相似文献   

基于CyGNSS数据的土壤水分与植被光学厚度反演研究     

严清赟  金双根  黄为民  贾燕  魏思远 《南京气象学院学报》2021,13(2):194-203

本文提出了一种仅基于CyGNSS数据,能够同时反演土壤水分与植被光学厚度的方案,该方案使用了神经网络与暴力穷举算法.首先考察了2018年以及2020年的数据,并对结果进行了验证.通过分析发现反演结果与参考数据展现了良好的一致性.土壤水分的反演结果与2018年和2020年的测试数据比较,其相关系数分别高达0.86和0.84,均方根误差分别为0.064和0.071 cm³/cm³;对于植被光学厚度,2018年与2020年的相关系数均为0.98,均方根误差分别为0.079和0.084.研究结果表明,CyGNSS可作为一种新型且独立的泛热带土壤水分与植被光学厚度反演手段.  相似文献   

Snow avalanche susceptibility evaluation in the central Shaluli Mountains of Tibetan Plateau based on machine learning method北大核心CSCD     

文洪  巫锡勇  赵思远  边瑞  周桂宇  孟少伟  孙春卫 《冰川冻土》2022,44(6):1694-1706

Snow avalanches,which are widely and frequently developed at high elevations,seriously threatens the built traffic corridors in the Tibetan Plateau. Susceptibility evaluation of snow avalanche via machine learning model with a high forecast accuracy can be appled to quickly and effectively assess the regional avalanche risk. This paper took the central Shaluli Mountain region as the study area,in which the snow avalanche inventory was established through remote sensing interpretation and field investigation verification. We quantitatively extracted 17 evaluation factors via GIS-based analysis,and these factors were selected through the variance expansion factor（VIF）. Four machine learning models containing SVM,DT,MLP and KNN were used to compile the susceptibility index map of snow avalanches,and kappa coefficient and ROC curve were used to verify the accuracy. The results suggested that the susceptibility indexes obtained from SVM,DT,MLP and KNN were in the range of［0,0. 964］,［0,815］,［0,0. 995］and［0,1］,respectively. The accuracy test results show that these four models all have good prediction accuracy. Among them,the SVM model is the best. The results also indicated that the areas with the high snow avalanche susceptibility mainly distributed in Genie Mountain and Rigong Mountain,most of which were above the planation surface of the Tibetan Plateau. The average altitude of the extremely high snow-avalanche-prone areas is 4 939 m,while the average altitude of the high snow avalanche-prone areas is 4 859 m. The snow avalanche has low perniciousness on the Sichuan-Tibet Highway and the Sichuan-Tibet Railway in the study area. This study can provide theoretical basis and method reference for disaster prevention and mitigation of snow avalanche along Sichuan-Tibet Railway and other major projects across Shaluli Mountains region. © 2022 Science Press (China).  相似文献   

隧道监测数据信息化技术及应用研究     

武胜林  邓洪亮  陈凯江  黄东辉  付思远  朱明岩 《测绘通报》2013,(8):25-27,48

隧道监控量测是隧道施工安全控制的一个十分重要的环节,是铁路客运专线隧道分步验收的重要内容之一,其目的是通过对隧道净空收敛和沉降观测进行数据分析,优化隧道施工方案和设计,确定合理的安全步距和支护时间,保障隧道施工和工后运营安全。虽然国内外对隧道监控量测工作十分重视,但目前监测水平与信息化施工要求还相差甚远。本文讨论隧道监测新技术和新方法,并对监测数据进行统计分析和反分析,提出监测数据信息化分析技术,并在工程实际中得到了应用,取得了较好的应用效果。  相似文献   

强电磁干扰下磁共振地下水探测噪声压制方法研究进展   总被引：1，自引：0，他引：1  

林君  张扬  张思远  舒旭  杜文元  林婷婷 《吉林大学学报(地球科学版)》2016,46(4):1221-1230

磁共振地下水探测方法因具有高分辨力、高效率、信息量丰富和解唯一等优点而备受地球物理工作者关注。近几年,该方法在正演模型和反演解释方面取得了显著的进展,在水文地质勘查方面的应用也进一步拓展。然而,磁共振信号极其微弱、对周围环境中的电磁干扰反映敏感,成为其应用的主要瓶颈。吉林大学地下水磁共振技术课题组针对噪声的产生机理及特性,对影响信号质量最严重的两类噪声--工频谐波噪声和尖峰脉冲噪声进行研究。本文综述了强电磁干扰下磁共振地下水探测噪声压制方法的研究现状及近期研究进展,包括磁共振信号的工频谐波噪声压制方法和尖峰脉冲噪声压制方法,简要介绍了实时参考消噪技术、独立分量分析技术、基于能量运算的尖峰噪声抑制技术以及基于同步压缩小波变换和自寻优非线性阈值补偿技术抑制电磁干扰的研究示例,展望了地下水磁共振探测噪声压制技术的未来发展趋势。  相似文献