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基于3S技术的宝天高速公路虚拟地理环境系统设计与实现 总被引：3，自引：3，他引：0
要建设兼顾交通、环保、生态等多方面要求的高标准山区高速公路,必须重视和加强地质环境工作,而遥感技术(RS)、地理信息系统(GIS)、全球定位系统(GPS)和虚拟地理环境技术可以在其中发挥巨大的辅助作用.依托宝(鸡)天(水)高速公路(牛背至天水段)项目,对3S(RS,GIS和GPS)技术支持下的道路虚拟地理环境设计与实现方法展开研究.讨论了系统建设的设计思路、方案和技术实现工作流程,以及数据建设工作流程,针对实际应用的需求,探讨了对系统整体性能进行优化的方法.研究表明,通过采用新的技术支持与实现手段,虚拟地理环境技术可以在道路工程建设过程的信息管理与信息可视化方面发挥巨大的辅助作用. 相似文献
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考虑地层变异特征一致性的围岩变形不确定性分析 总被引：1，自引：0，他引：1
目前地层变异性分析大多基于地层重复性沉积和变异特征一致性假设,而未考虑地质构造和风化作用的影响,忽略了地层变异性特征一致性的检验。为此,提出地层变异特征一致性的检验和分区方法,采用岩土相局部状态转移概率矩阵的相关系数作为一致性的定量判据,基于耦合Markov链模型模拟地层分布,并通过Monte Carlo方法分析隧道围岩变形的不确定性。利用青岛轨道交通某斜井的地质钻孔数据,探讨了地层变异特征一致性对地层分布和变形模拟精度的影响,分析了所提方法的有效性。结果表明,当地质构造和风化作用导致地层变异特征不一致时,增加钻孔数量无法提高地层分布模拟精度,采用所提方法对地层变异特征一致性检验并分区后,可避免状态转移概率矩阵中局部地层分布特征缺失的问题,提高围岩变形不确定性分析的准确性。 相似文献
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《Chinese Astronomy and Astrophysics》2022,46(3):249-263
The direct-imaging exploration can obtain comprehensive physical information of exoplanets, which is a key technology to search for extraterrestrial life in the future. In this paper, based on our recent high-contrast imaging data of ground-based telescope, the newly discovered multi-star candidates are presented. In the early stage, combined with the ability of high-contrast imaging equipment for the exoplanets in the ground-based system, we select about 1000 targets from published works which are compiled using the catalogs released by Gaia. These targets are distributed in different young star clusters. Recently, we used Hale Telescope at Palomar Observatory to carry out high-contrast imaging observation on 42 of the above targets in the K-band. Most of the observed targets are 7.5–14 in the V-band. In 2019, after two rounds of observation, we discover six multi-star system candidates. It is however difficult to find out whether these targets are single-star or multi-star systems in Gaia DR2 (Data Release 2) catalog and Gaia EDR3 (early Data Release 3) catalog. 相似文献
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《Journal of Atmospheric and Solar》2007,69(12):1459-1470
A new empirical model for the lower ionosphere in the auroral zone, called IMAZ, has been developed, tested and refined for use in the International Reference Ionosphere (IRI) global model. Available ionospheric data have been used to train neural networks (NNs) to predict the high latitude electron density profile. Data from the European Incoherent Scatter Radar (EISCAT), based near Tromsø, Norway (69.58°N, 19.23°E), combined with rocket-borne measurements (from 61° to 69° geomagnetic latitude) make up the database of reliable D- and E-region data.NNs were trained with different combinations of the following input parameters: day number, time of day, total absorption, local magnetic K index, planetary Ap index, 10.7 cm solar radio flux, solar zenith angle and pressure surface. The output that the NNs were trained to predict was the electron density for a given set of input parameters. The criteria for determining the optimum NN are (a) the root mean square (RMS) error between the measured and predicted output values, and (b) the ability to reproduce the absorption they are meant to represent. An optimum input space was determined and then adapted to suit the requirements of the IRI community. In addition, the true quiet electron densities were simulated and added to the database, thus allowing the final model to be valid for riometer absorptions down to 0 dB.This paper discusses the development of a NN-based model for the high-latitude, lower ionosphere, and presents results from the version developed specifically for the IRI user community. 相似文献
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震后崩塌是强烈地震造成的震裂山体在后期余震、降雨及重力作用下变形不断发展并再次发生的崩塌。基于对四川省省道S303线映秀-卧龙段震后公路边坡崩塌灾害的调查,通过空间分布、崩塌与物质组成、岩性、失稳斜坡坡度、坡高、坡形、坡向和崩塌形成机理的关系等方面的分析,得到了震后崩塌灾害的发育规律:1.震后崩塌分布规律与地震时引发的崩塌的规律一致,即地震时易发生崩塌的地段地震后仍然易发生崩塌。2.按照边坡物质组成,以岩质边坡崩塌占绝大多数,岩土组合体边坡次之;较坚硬岩石中发生的崩塌多而较弱岩石中发生崩塌少,沿线发生崩塌最多的是岩性为闪长岩、辉长岩和变质砂岩等坚硬岩石组成的斜坡。3.失稳斜坡坡度在36°～85°之间,主要分布在41°～60°之间,即震后崩塌灾害主要发生在40°以上的斜坡。映秀-耿达段和耿达-卧龙段发生崩塌的边坡坡度有明显的差别,映秀-耿达段集中在坡度为46°～60°的斜坡,而耿达-卧龙段集中在在坡度为41°～55°的斜坡。4.绝大多数崩塌发生在坡高150 m以内的斜坡上,映秀-耿达段和耿达-卧龙段发生崩塌的边坡高度有明显的差别,映秀-耿达段集中在高度为51～350 m的斜坡,而耿达-卧龙段集中在在高度<200 m的斜坡,尤以高度<100 m的最多。5.阳坡和阴坡的崩塌数量有明显的差异,阳坡发生崩塌的数量远远大于阴坡崩塌发生的数量。6.震后边坡崩塌的形成机理以滑移式崩塌和倾倒式为主。映秀-耿达段和耿达-卧龙段地处不同地质构造单元,由于岩性的差异,发生崩塌的斜坡的坡度、高度和主要形成机理具有差异性。 相似文献
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Z.-J. Hu H. Yang D. Huang T. Araki N. Sato M. Taguchi E. Seran H. Hu R. Liu B. Zhang D. Han Z. Chen Q. Zhang J. Liang S. Liu 《Journal of Atmospheric and Solar》2009,71(8-9):794-804
Observations acquired from three-wavelength (427.8, 557.7 and 630.0 nm) all-sky imagers (ASIs) at Yellow River Station (YRS) in Ny-Ålesund, Svalbard, are used to examine the synoptic distribution of dayside aurora. The results demonstrate that the maximum emission regions (MERs) at each wavelength are all located in the postnoon sector, but have rather different magnetic local time (MLT) distributions from each other. The so-called 15 MLT “hot spot” is the overlapping region of the MERs at three wavelengths, and the prenoon “warm spot” is characterized uniquely by an increase of emissions at the 557.7 nm wavelength. The detailed dayside auroral spectra and morphology as a function of MLT are discussed. 相似文献
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《Quaternary Science Reviews》2005,24(1-2):173-194
The climate history and dynamics of the Greenland Ice Sheet are studied using a coupled model of the depositional provenance and transport of glacier ice, allowing simultaneous prediction of the detailed isotopic stratigraphy of ice cores at all the major Greenland sites. Adopting a novel method for reconstructing the age–depth relationship, we greatly improve the accuracy of semi-Lagrangian tracer tracking schemes and can readily incorporate an age-dependent ice rheology. The larger aim of our study is to impose new constraints on the glacial history of the Greenland Ice Sheet. Leading sources of uncertainty in the climate and dynamic history are encapsulated in a small number of parameters: the temperature and elevation isotopic sensitivities, the glacial–interglacial precipitation contrast and the effective viscosity of ice in the flow law. Comparing predicted and observed ice layering at ice core sites, we establish plausible ranges for the key model parameters, identify climate and dynamic histories that are mutually consistent and recover the past depositional elevation of ice cores to ease interpretation of their climatic records. With the coupled three-dimensional model of ice dynamics and provenance transport we propose a method to place all the ice core records on a common time scale and use discrepancies to adjust the reconstructed climate history. Analysis of simulated GRIP ice layering and borehole temperature profiles confirms that the GRIP record is sensitive to the dynamic as well as to the climatic history, but not enough to strongly limit speculation on the state of the Greenland Ice Sheet during the Eemian. In contrast, our study indicates that the Dye 3 and Camp Century ice cores are extremely sensitive to ice dynamics and greatly constrain Eemian ice sheet reconstructions. We suggest that the maximum Eemian sea-level contribution of the ice sheet was in the range of 3.5–4.5 m. 相似文献
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土工合成材料在多年冻土地区路基病害处治中的应用技术研究 总被引：10，自引：3，他引：7
纵向裂缝与不均匀变形是多年冻土地区路基病害的主要类型,成因复杂,久治不愈.综合国内外现有成果,对于路基不均匀变形,根据其成因,分别提出了土工合成材料处治不均匀变形技术与土工合成材料处治路基阳坡变形技术等处治措施.对于路基纵向裂缝,根据其不同分类与不同严重程度,分别提出了土工合成材料处治纵向裂缝技术、柔性枕梁处治技术、边坡分层加筋处治技术等处治措施;根据多年冻土地区路基特点与环境条件,从土工合成材料的强度特性、构造特性、耐久性及抗施工损伤性能等方面,提出了土工合成材料选择时的原则.结合青藏公路纵向裂缝处治工程,研究了土工合成材料处治病害施工技术,解决了该地区使用土工合成材料时的工程关键技术. 相似文献
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