渤海LZK06孔25万年沉积物粒度特征及沉积环境意义          下载免费PDF全文

王忱沛  李琰  商志文  姜兴钰  李建芬  胡克  王宏 《海洋科学进展》2022,40(1):66-78

对渤海北岸大凌河冲积平原的LZK06孔上部60 m沉积物开展了粒度测试,分析了粒度特征变化规律,探讨了控制粒度特征变化的因素及其对环境演化的指示.结果 显示,LZK06孔沉积物以下部陆相沉积和上部海陆交互相沉积为特点.LZK06孔沉积物粒度整体较粗,指示了较强的沉积水动力.整体上海相沉积物粒度略粗于下伏陆相沉积物.地层...  相似文献   

Reduced complexity models for probabilistic forecasting of infiltration rates     

Peng Wang Daniel M. Tartakovsky 《Advances in water resources》2011,34(3):375-382

Soil heterogeneity and data sparsity combine to render estimates of infiltration rates uncertain. We develop reduced complexity models for the probabilistic forecasting of infiltration rates in heterogeneous soils during surface runoff and/or flooding events. These models yield closed-form semi-analytical expressions for the single- and multi-point infiltration-rate PDFs (probability density functions), which quantify predictive uncertainty stemming from uncertainty in soil properties. These solutions enable us to investigate the relative importance of uncertainty in various hydraulic parameters and the effects of their cross-correlation. At early times, the infiltration-rate PDFs computed with the reduced complexity models are in close agreement with their counterparts obtained from a full infiltration model based on the Richards equation. At all times, the reduced complexity models provide conservative estimates of predictive uncertainty.  相似文献   

矢量地图数据数字水印技术综述     

杨辉  闵连权  侯翔 《测绘与空间地理信息》2014,(3):9-12,30

矢量地图数据在网络环境下的共享机制,给各个领域都带来了极大的便利,但是其安全和版权保护问题也日益突出。数字水印技术作为版权保护的一种有效方法,成为人们关注的一个焦点。本文分析了矢量地图数据自身特点和常见处理方式;从建立映射关系、构造嵌入域、嵌入方式等3个步骤对空间域水印算法进行了详细分析,分析每种算法的优缺点,为下一步水印算法提供指导;对频率域水印算法进行了研究,并指出了频率域水印算法存在的问题;指出了矢量地图数据水印进一步的研究方向。  相似文献   

浅议高精度遥感正射影像的获取     

赵丽梅 《东北测绘》2014,(2):106-109

阐述了应用高分辨率卫星WorldView-2获取的地球表面沈阳市域影像数据制作沈阳市正射遥感影像图的工艺,并介绍了VirtuoZo NT（全数字摄影测量系统）及ENVI（遥感地物定量化工具）、EPT（易拼图）在制作正射影像图过程中的应用。  相似文献   

Damage identification using inverse analysis in coupled thermo‐hydro‐mechanical problems applied to masonry dams          下载免费PDF全文

Long Nguyen‐Tuan  Carsten Könke  Volker Bettzieche  Tom Lahmer 《国际地质力学数值与分析法杂志》2018,42(2):256-273

In this paper, we propose a method to detect the damage and estimate the degree of damage by means of a multifield‐based inverse analysis. The fields being considered are displacement, temperature, and water pressure. Furthermore, the uncertainties due to the size of the damage, the errors in the measurement data, and the errors in the model parameters are also investigated. The uncertainty due to the measurements is quantified by assuming different sources of noise in the measurements. The inverse problem is solved repeatedly by a sampling process. The uncertainties in the inverse solutions can be quantified by their probability distributions. This method can be applied to identify damages in masonry dams using coupled nonlinear thermo‐hydro‐mechanical problems.  相似文献   

基于改进的数量化理论和RBF神经网络组合方法的地下水水质预测     

杨平  王新民  路来君 《地学前缘》2016,23(3):151-155

文中首先运用了一种改进的数量化理论I模型作为预处理工具,对影响地下水水质的20个因子进行定性数据转换、数据降维,随后将8个重要特征因子作为RBF（径向基函数）神经网络模型的输入,进一步对监测井的采样数据进行学习、训练,揭示地下水污染质迁移转化规律。尝试用经过改进的数量化理论与RBF神经网络方法二者结合,对沈阳李官水源地研究区监测井地下水水质变化进行模拟与预测,其仿真结果覆盖了现有的绝大部分实测数据,适用范围广泛,具有一定的推广价值。  相似文献   

全新世以来浙江余姚河姆渡—田螺山遗址的古环境演变及人类活动^*   总被引：1，自引：0，他引：1       下载免费PDF全文

郑丽波  郝秀东  禚彬  柳云龙  王小龙  朱立新  余新波  张甬江 《古地理学报》2016,18(5):879-894

通过对浙江余姚河姆渡—田螺山遗址附近的HMD1501和HMD1502两个钻孔的微体古生物学研究,揭示了该地区全新世以来的植被演变、气候变化、海平面变迁及人类活动。孢粉、海相沟鞭藻、淡水藻类及有孔虫内衬的记录表明: (1)在早全新世(对应于镇海组下部),植被群落属于常绿阔叶和针叶混交林,气候温暖潮湿,研究区属于海侵阶段。(2)在中全新世(对应于镇海组中部),植被群落虽仍为针阔叶混交林,但气候转为温和湿润,研究区仍属于海侵阶段。(3)由于人类活动的进一步加剧,在晚全新世(对应于镇海组上部)的植被群落中草地的面积也随之扩大,并在滨海地区开始有一些以莎草科为主的沼泽地形成,植被群落属于针阔叶混交林—草地,气候更加凉爽干燥,研究区转为海退阶段。(4)在~7235—3327 cal. yr B.P.期间,草本花粉的含量激增,特别是一些粒径不小于35,μm 的禾本科栽培作物花粉的含量增加,说明此时人类活动开始增强,河姆渡—田螺山遗址附近出现较多的水稻种植区。  相似文献   

An integrated field and numerical modelling study of controls on Late Quaternary fluvial landscape development (Tabernas,southeast Spain)          下载免费PDF全文

Martin R. Geach  Willem Viveen  Anne E. Mather  Matt W. Telfer  William J. Fletcher  Martin Stokes  Odile Peyron 《地球表面变化过程与地形》2015,40(14):1907-1926

The variability of Quaternary landforms preserved in the Tabernas basin of southeast (SE) Spain raises numerous questions concerning the roles of external forcing mechanisms (e.g. tectonics and/or climate) and internal landscape properties (e.g. lithological controls) in the evolution of the basin‐wide fluvial system over Late Quaternary timescales. In this study, we apply the FLUVER2 numerical model to investigate the significance of these landscape controls upon patterns of landscape evolution. We highlight the complications of generating realistic input datasets for use in the modelling of long‐term landscape evolution (e.g. discharge and runoff datasets). Model outputs are compared to extensive field mapping of fluvial terraces, their sedimentary architecture and optically stimulated luminescence dating results of the terraces. The results demonstrate the significance of non‐linear rates of flexural tectonic uplift towards the west of the Tabernas Basin which have controlled base levels throughout the Quaternary and promoted the formation of a series of diverging fluvial terraces. Our numerical model results further highlight the importance of climate cycles upon river terrace formation. Basin‐wide aggradation events were modelled during the transition from Marine Isotope Stage (MIS) 6 to 5 and the Last Glacial Maximum (LGM) as supported by field evidence. This aggradational pattern supports the regional hypothesis of terrace formation during global glacial cycles and cold‐to‐warm stage transitions and supports the use of sea surface temperature climate proxy data in the modelling exercise. The availability of sediments derived from the surrounding hillslopes and adjacent alluvial fans explains the generation of substantial terrace aggradations. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

数量化理论Ⅲ在瓦斯突出预测敏感地质指标筛选中的应用   总被引：2，自引：0，他引：2  

吴财芳  秦勇  张许良 《工程地质学报》2005,13(2):263-268

论述了数量化理论及数量化理论Ⅲ的基本原理,提出了反应标度的概念和计算方法,扩展了原来反应取值的适用范围和科学性。以中马村矿区为研究实例,研究了影响煤与瓦斯突出的地质因素,并采用统计单元划分结合数量化理论Ⅲ的方法,从11个地质因素中筛选出8个瓦斯突出预测敏感地质指标,并据此对中马村矿已采区进行了瓦斯地质区划。实践表明:将数量化理论Ⅲ应用于瓦斯地质学是可行的,为瓦斯突出预测敏感地质指标的筛选提供了新的思路。  相似文献   

孟加拉湾中部表层沉积物常微量元素地球化学:物源指示意义     

李景瑞  刘升发  冯秀丽  孙兴全  石学法 《海洋学报(英文版)》2017,36(3):82-90

通过对取自孟加拉湾中部的110个表层沉积物样品进行了常微量元素测试分析,探讨了其物质来源。在所有测试元素中,Si含量最高,其次为Al,且这两种元素的分布特征基本一致。化学蚀变指数（CIA^*）平均值为72.07,指示研究区沉积物风化程度位于喜马拉雅源区和印度源区沉积物之间。因子分析和判别函数计算分析表明研究区沉积物主要来自喜马拉雅源区和印度源区。使用Ti标准化后的元素比值反演模型估算的喜马拉雅源区和印度源区对研究区沉积物的相对贡献比例分别为83.5%和16.5%。其中,喜马拉雅源区对研究区东部沉积物贡献相对较大,而在研究区西部印度源区贡献比例相对东部为高。喜马拉雅源区物质向研究区输运的主要动力机制包括浊流及其溢流、表层季风环流携带的河流冲淡水,而印度源区物质主要通过表层季风环流特别是东印度沿岸流向研究区输运  相似文献