一种海洋混合层深度的智能识别方法研究     

张康  郭双喜  黄鹏起  屈玲  鲁远征  岑显荣  于璐莎  周伟东  周生启 《热带海洋学报》2019,38(5):32-41

文章提出了一种识别混合层深度的人工智能方法。该方法在温度(密度)与压强(或深度)间建立线性模型, 并且将其系数和方差做成一组表征廓线特征的统计量。初始时为模型设定一个主观的先验分布, 在一个自海表向下移动的窗口内通过贝叶斯链式法则和最小描述长度原理学习新数据, 得到系数均值的最大后验概率估计。用F-检验识别系数发生突变的位置, 以此确定混合层的存在性及其深度。通过2017年2月太平洋海域的地转海洋学实时观测阵(Array for Real-time Geostrophic Oceanography, ARGO)数据进行测试, 并且以质量因子(Quality Index, QI)值作为判断识别混合层深度结果准确性的依据, 发现该方法相比于梯度法、阈值法、混合法、相对变化法、最大角度法和最优线性插值法在识别结果上具备更大的QI值。表明该方法能够准确识别混合层深度。  相似文献   

Analytical modeling on consolidation of stiffened deep mixed column-reinforced soft soil under embankment     

Zhen Zhang  Fengrui Rao  Guanbao Ye 《国际地质力学数值与分析法杂志》2020,44(1):137-158

Stiffened deep mixed (SDM) column is a new ground improvement technique to improve soft soil, which can be used to increase bearing capacity, reduce deformation, and enhance stability of soft soil. This technique has been successfully adopted to support the highway and railway embankments over soft soils in China and other countries. However, there have been limited investigations on its consolidation under embankment loading. This paper developed an analytical solution for the consolidation of embankment over soft soil with SDM column in which core pile is equal to or shorter than outer DM column. The consolidation problem was simplified as a consolidation of composite soil considering the load shear effect of core pile. The developed solution was verified by a comparison with the results computed by three-dimensional (3-D) finite element analysis. A parametric study based on the derived solution was conducted to investigate influence factors—length of core pile, diameter of core pile, diameter of SDM column, modulus of DM column, and permeability coefficient of DM column—on the consolidation behavior of SDM column-supported embankment over soft soil. The developed solution was applied to a case history of SDM column-supported embankment, and a good agreement was found between the predictions and the field measurements.  相似文献   

深海弯曲水道内部一种特殊的沉积单元:凹岸坝     

冯潇飞  赵晓明  谭程鹏  齐昆  谢涛  张迎春  陆文明  徐睿 《沉积学报》2020,38(2):440-450

在深海水道研究过程中,识别出深海弯曲水道内部存在一种特殊的沉积单元--凹岸坝,基于尼日尔三角洲陆坡区浅层高频三维地震资料,利用地震相分析技术,探究了凹岸坝的沉积结构特征和形成机制,讨论了其与水道弯曲丘(nested mounds)、曲流河凹岸滩坝之间的差异。研究结果表明:凹岸坝是分布于曲率较大、以垂向加积为主的末期水道弯曲凹岸处的坝体沉积单元,该沉积单元在地震剖面上表现为强振幅、连续性较好的反射特征,其内部沉积界面倾向于水道弯曲凸岸处,倾角约1°~20°,且在凹岸弧顶处达到最大值。凹岸坝形成的关键在于惯性作用,其造成水道内部重力流流体在弯曲处发生溢岸,导致流量减少,流体动能相应降低,流体携砂能力小于沉积物负载,造成沉积物快速沉降,从而形成凹岸坝。由于凹岸坝是一种连续性较好的砂体沉积,所以其可成为潜在的、储集性能较好的油气储集体。  相似文献   

CG-6型重力仪零漂特性研究     

郝洪涛  刘少明  韦进  胡敏章 《大地测量与地球动力学》2019,39(10):1086-1090

对中国地震局地震研究所最新引进的4台CG-6型相对重力仪的零漂特性进行测试研究，结果表明，4台重力仪的静态零漂率、混合零漂率和动态零漂率均小于8 μGal/h，满足厂家给出的技术指标。在较长观测时间内，各台仪器的零漂均存在不同程度的非线性特征，因此在进行较长时间的野外观测以及后续数据处理中，不宜将零漂率作为常数进行解算和零漂改正。  相似文献   

南大洋混合层的时空变化特征     

应美佳  刘海龙  王夫常  张召儒  钟贻森 《海洋与湖沼》2019,50(6):1223-1232

过去对南大洋的研究受限于长期观测的缺乏,而现在地转海洋学实时观测阵(Arrayfor Real-timeGeostrophicOceanography,Argo)项目自开始以来持续提供了高质量的温度盐度观测,使系统地研究南大洋海洋上层结构成为可能。本研究使用2000—2018年的Argo浮标观测数据,分析了南大洋混合层深度(Mixed Layer Depth, MLD)的时空分布特征。结果表明:南大洋混合层存在明显的季节变化,冬春两季MLD在副南极锋面北侧达到最高值并呈带状分布,夏秋两季由于海表加热导致混合层变浅,季节变化幅度达到400m以上;在年际尺度上,MLD受南半球环状模(Southern HemisphereAnnularMode,SAM)调制,呈现纬向不对称空间分布特征,这与前人结果一致;本文指出在所研究时段,南大洋混合层在90°E以东,180°以西有加深趋势,而在60°W以西,180°以东有变浅趋势,显示出偶极子分布特征,并且这种趋势特征主要是风场的作用。  相似文献   

福州市地表温度热点及时空变化分析     

陈冰倩  张友水  程璟媛  赵雪 《地球信息科学学报》2019,21(5):710-719

中国作为世界第一大发展中国家,近年来城镇化发展迅速,大量自然地表转化为人工地表,从而引起了一系列环境问题,其中以城市热岛问题最为显著。因此如何缓解因城市化进程的加快引起的城市热岛效应已成为热门研究方向。为精确分析城市空间格局对热集聚的影响,本研究利用2000年5月4日的Landsat ETM+和2016年7月27日获取的Landsat OLI两期遥感影像,获取福州市的土地覆盖信息并进行精度验证。在地表温度（Land Surface Temperature, LST）反演基础上通过热点分析（Getis-Ord Gi*）,并结合不透水面（Impervious Surface Area, ISA）信息来研究城市化进程中福州市16 年来 LST的变化特性,空间集聚特性及其产生的尺度效应。热点分析结果显示：① 通过分析福州市内各地和热点中心的距离与LST的关系可较好地反映空间热聚集。2000 年在距热点中心0.97、1.03、0.95 km范围内热聚集明显;2016 年则增长到分别在距热点中心半径1.89、2.01、2.10、2.05、2.13 km范围内热集聚显著且热点区数量也从3 个增加至5 个。热集聚区（热点区和较热区）总面积在此期间从15.7%增至47.3%;② 由于热点图中的热点区和冷点区的形成不单取决于LST的高低,因此热点分析与空间自相关分析方法相比,能更直观地分析土地覆盖变化对LST的影响,了解城市内部热强度变化的细节。本研究采用的热点分析方法可用于城市环境保护与规划,将来还可作为城市土地规划与热环境影响的分析依据。同时可利用热点分析图模拟城市微气候,估算城市绿地降温程度等。此外,未来还可基于此进一步探讨更多时相以及不同城市的对比分析,特别是对不同城市类型如带状城市,多中心城市及中心城市等的研究。  相似文献   

Depositional processes of the Zhushadong and Mantou formations (Early to Middle Cambrian), Shandong Province,China: roles of archipelago and mixed carbonate–siliciclastic sedimentation on cycle genesis during initial flooding of the North China Platform     

SUNG KWUN CHOUGH 《Sedimentology》2011,58(6):1530-1572

To understand the depositional processes and environmental changes during the initial flooding of the North China Platform, this study focuses on the Lower to Middle Cambrian Zhushadong and Mantou formations in Shandong Province, China. The succession in the Jinan and Laiwu areas comprises mixed carbonate and siliciclastic deposits composed of limestone, dolostone, stromatolite, thrombolite, purple and grey mudstone, and sandstone. A detailed sedimentary facies analysis of seven well‐exposed sections suggests that five facies associations are the result of an intercalation of carbonate and siliciclastic depositional environments, including local alluvial fans, shallowing‐upward carbonate–siliciclastic peritidal cycles, oolite dominant shoals, shoreface and lagoonal environments. These facies associations successively show a transition from an initially inundated tide‐dominated carbonate platform to a wave‐dominated shallow marine environment. In particular, the peritidal sediments were deposited during a large number of depositional cycles. These sediments consist of lime mudstone, dolomite, stromatolite and purple and grey mudstones. These shallowing‐upward cycles generally resulted from carbonate production in response to an increase of accommodation during rising sea‐level. The carbonate production was, however, interrupted by frequent siliciclastic input from the adjacent emergent archipelago. The depositional cycles thus formed under the influence of both autogenetic changes, including sediment supply from the archipelago, and allogenic control of relative sea‐level rise in the carbonate factory. A low‐relief archipelago with an active tidal regime allowed the development of tide‐dominated siliciclastic and carbonate environments on the vast platform. Siliciclastic input to these tidal environments terminated when most of the archipelago became submerged due to a rapid rise in sea‐level. This study provides insights on how a vast Cambrian carbonate platform maintained synchronous sedimentation under a tidal regime, forming distinct cycles of mixed carbonates and siliciclastics as the system kept up with rising relative sea‐level during the early stage of basin development in the North China Platform.  相似文献   

基于混合像元分解提取多种类覆盖区遥感蚀变信息 ——以甘肃省岷县寨上金矿区为例     

陈勇敢 《地质与勘探》2011,47(6):1171-1176

在多种类覆盖区,由于植被、河道、阴影、第四系等干扰因素影响,难于客观有效提取与成矿有关的遥感蚀变信息。应用混合像元分解的方法技术可以区分出混合像元中各类干扰信息的反射率值及其所占丰度值,从混合像元光谱中减去各干扰因素的反射率值及其所占份额,可以获取土壤或岩石的反射率值及其所占丰度值,将土壤或岩石反射率值除以其所占的份额...  相似文献   

长江口外海域表层沉积物微量元素地球化学特征   总被引：1，自引：1，他引：0  

蓝先洪  张志殉  李日辉  王中波  陈晓辉  侯方辉 《现代地质》2011,25(6)

对采自长江口外海域187个表层沉积物的25个微量元素含量进行了标准差系数、相关分析及R型因子分析,探讨了微量元素的来源和分布特征。长江口外海域沉积物微量元素Li、V、Cr、Co、Ni、Ga、Cu、Zn、Th和Rb分布基本相似;Sr分布与Li、Cu、Pb、Zn、Th和Rb相反;研究区东南部Sr分布与生物作用有明显关系;Cd和Mo分布与粒度之间的相关性较差,主要受氧化还原环境的控制;Zr分布反映了长江物源的影响。相关分析和R型因子分析结果表明,沉积作用、粒度控制效应、海洋生物作用、氧化还原环境和源区地质背景等对长江口外海域表层沉积物中微量元素分布起着主要控制作用。  相似文献   

Hybrid Sedimentation in Late Permian-Early Triassic in Western Sichuan Basin,China     

龙胜祥  吴世祥  李宏涛  白振瑞  马金钰  张华 《中国地质大学学报(英文版)》2011,(3)

Mixed carbonate-siliciclastic sedimentation is common in the Upper Permian-Lower Tri-assic in the western Sichuan(四川) basin.The extensional movement was strong in the Late Permian,resulting in differential uplifting of fault blocks.During this period,there was an extensive retrogres-sion.The Kangdian(康滇) ancient land progressive uplifted and enlarged,forming the major prove-nance of terrigenous clastics.In Changxingian age,mixed terrigenous-carbonate sedimentation was dis-tributed in the area between Dafeis...  相似文献