Formal subdivision of the Holocene Series/Epoch: a Discussion Paper by a Working Group of INTIMATE (Integration of ice‐core,marine and terrestrial records) and the Subcommission on Quaternary Stratigraphy (International Commission on Stratigraphy)     

M. J. C. Walker  M. Berkelhammer  S. Björck  L. C. Cwynar  D. A. Fisher  A. J. Long  J. J. Lowe  R. M. Newnham  S. O. Rasmussen  H. Weiss 《第四纪科学杂志》2012,27(7):649-659

This discussion paper, by a Working Group of INTIMATE (Integration of ice‐core, marine and terrestrial records) and the Subcommision on Quaternary Stratigraphy (SQS) of the International Commission on Stratigraphy (ICS), considers the prospects for a formal subdivision of the Holocene Series/Epoch. Although previous attempts to subdivide the Holocene have proved inconclusive, recent developments in Quaternary stratigraphy, notably the definition of the Pleistocene–Holocene boundary and the emergence of formal subdivisions of the Pleistocene Series/Epoch, mean that it may be timely to revisit this matter. The Quaternary literature reveals a widespread but variable informal usage of a tripartite division of the Holocene (‘early’, ‘middle’ or ‘mid’, and ‘late’), and we argue that this de facto subdivision should now be formalized to ensure consistency in stratigraphic terminology. We propose an Early–Middle Holocene Boundary at 8200 a BP and a Middle–Late Holocene Boundary at 4200 a BP, each of which is linked to a Global Stratotype Section and Point (GSSP). Should the proposal find a broad measure of support from the Quaternary community, a submission will be made to the International Union of Geological Sciences (IUGS), via the SQS and the ICS, for formal ratification of this subdivision of the Holocene Series/Epoch. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Calibrating a glaciological model of the Greenland ice sheet from the Last Glacial Maximum to present-day using field observations of relative sea level and ice extent     

Matthew J.R. Simpson  Glenn A. Milne  Philippe Huybrechts  Antony J. Long 《Quaternary Science Reviews》2009,28(17-18):1631-1657

We constrain a three-dimensional thermomechanical model of Greenland ice sheet (GrIS) evolution from the Last Glacial Maximum (LGM, 21 ka BP) to the present-day using, primarily, observations of relative sea level (RSL) as well as field data on past ice extent. Our new model (Huy2) fits a majority of the observations and is characterised by a number of key features: (i) the ice sheet had an excess volume (relative to present) of 4.1 m ice-equivalent sea level at the LGM, which increased to reach a maximum value of 4.6 m at 16.5 ka BP; (ii) retreat from the continental shelf was not continuous around the entire margin, as there was a Younger Dryas readvance in some areas. The final episode of marine retreat was rapid and relatively late (c. 12 ka BP), leaving the ice sheet land based by 10 ka BP; (iii) in response to the Holocene Thermal Maximum (HTM) the ice margin retreated behind its present-day position by up to 80 km in the southwest, 20 km in the south and 80 km in a small area of the northeast. As a result of this retreat the modelled ice sheet reaches a minimum extent between 5 and 4 ka BP, which corresponds to a deficit volume (relative to present) of 0.17 m ice-equivalent sea level. Our results suggest that remaining discrepancies between the model and the observations are likely associated with non-Greenland ice load, differences between modelled and observed present-day ice elevation around the margin, lateral variations in Earth structure and/or the pattern of ice margin retreat.  相似文献   

Ultraviolet Studies of Interacting Binaries     

Boris T. Gänsicke  Domitilla de Martino  Thomas R. Marsh  Carole A. Haswell  Christian Knigge  Knox S. Long  Steven N. Shore 《Astrophysics and Space Science》2006,306(3):177-177

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A long-term volume transport time series estimated by combining in situ observation and satellite altimeter data in the northern South China Sea   总被引：1，自引：0，他引：1  

Xiao-Hua Zhu  Ruixiang Zhao  Xinyu Guo  Yu Long  Yun-Long Ma  Xiaopeng Fan 《Journal of Oceanography》2015,71(6):663-673

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Numerical and Experimental Analysis of A Ducted Propeller Designed by A Fully Automated Optimization Process Under Open Water Condition     

余龙  Markus DRUCKENBROD  Martin GREVE  王珂琦  Moustafa ABDEL-MAKSOUD 《海洋工程》2015,29(5):733-744

A fully automated optimization process is provided for the design of ducted propellers under open water conditions, including 3D geometry modeling, meshing, optimization algorithm and CFD analysis techniques. The developed process allows the direct integration of a RANSE solver in the design stage. A practical ducted propeller design case study is carried out for validation. Numerical simulations and open water tests are fulfilled and proved that the optimum ducted propeller improves hydrodynamic performance as predicted.  相似文献   

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李德前  陈慧杰  魏贵春  孙伶俐  戴苗  贺玉方 《大地测量与地球动力学》2015,35(2):356-359

??????????????????????????????????????????????????????в?????????????????????????????????????????????≤1 nT/m????????????≤0.1 nT?????????????????????????????????????????????????????в???????????????????????????????????  相似文献   

一般地形大光斑激光测高回波模拟研究   总被引：1，自引：0，他引：1  

潘浩  李国元  王华斌  谭天亚  王伶俐 《地理信息世界》2015,(2)

国内对基于陆地模型的地表回波仿真的研究较多,主要分析了三种特定的地表模型:平面、阶梯、斜坡地形,取得了不错的进展,但是却不具有一般性。针对这种情况,本文从一般性地表模型出发,根据实际的地形三维离散点,用Delaunay三角形剖分拟合出地表模型,用剖分后的三角面片返回的能量代表整个地表返回的能量,拟合出回波波形。通过和GLAS系统获取的相同区域的实际回波波形进行相关性比较,结果发现两者具有很好的相关性,验证了算法的正确性。文章结论为后续继续深入开展激光大光斑内精细地形信息分析、激光测高数据与光学影像复合处理提供了理论基础,为发展我国自主的星载激光测高卫星的有关指标论证提供参考。  相似文献   

倾斜摄影技术在丘陵山区大比例尺测图中的应用     

何敏  熊先才  李晓俊  赵龙 《测绘通报》2021,(2):93-97,107

针对丘陵山区大比例尺测图应用的需求,本文探讨了如何通过倾斜摄影的技术方法获取高精度的影像模型。首先通过分析航线布设方法、控制点布设采集要点、空三数据处理关键点等,获取满足丘陵山区大比例尺测图应用的数据模型,基于数据模型获取大比例尺地形图数据;然后通过与实地测量数据进行精度对比分析获取试验结果,结果表明倾斜摄影技术不但能满足丘陵山区1：1000大比例尺测图的精度要求,而且大大提高了工作效率。  相似文献   

面向地图图片识别的两种卷积神经网络分析     

白又达  刘纪平  黄龙  白敬辉  车向红 《测绘科学》2021,46(11):126-134

针对目前多种网络基于小数据集或国际通用的一些标准数据集进行训练与测试,无法满足从互联网图片中高效识别出地图图片的需求,该文构建了一套基于卷积神经网络的互联网图片分类体系,对自动采集的92543张互联网图片经类型标注后形成样本库,将样本输入残差网络ResNet50和轻量级网络SqueezeNet中进行训练及测试.结果 显示:在地图类中,ResNet50的精确率、召回率分别比SqueezeNet高2.01％、0.32％;前者所耗费的训练、测试时间分别为后者的2.51倍、6.43倍,将上述指标进行归一化处理来综合评价两种网络在地图图片识别中的优越性.得出结论:SqueezeNet网络在地图识别应用中更具优越性,可有效提升在互联网地图图片中所包含"问题地图"的审查效率和及时响应服务.  相似文献   

基于Maptalks的外业草图绘制捕捉插件的设计与实现     

钱隆  罗年学  陈烁 《测绘地理信息》2021,46(3):134-136

作为中国为数不多的自主研发的开源地图引擎,Maptalks以其优良的性能和灵活的插件构建方式,在越来越多的项目中得以应用.鉴于其正处于稳步开发的阶段,部分功能还不够完善,还未实现实际项目中的草图绘制编辑所需的捕捉功能.针对此问题,开发了基于Maptalks的捕捉插件,实现了地图编辑中的捕捉功能.此成果一方面满足了外业草图绘制简单捕捉编辑的需求,另一方面完善了Map-talks的功能,扩大了它的应用范围.  相似文献