长江口新桥水道动力地貌变化过程研究

以泰国湾 T155号柱状沉积物为研究对象,利用地球化学和矿物学手段探讨了全新世以来泰国湾古气候演化历史。(La/Sm)UCC-(Gd/Yb)UCC指示了全新世以来泰国湾西南部物质来源较为稳定,主要来自于马来半岛,季风控制下的沿岸流是其主要驱动力。通过对高岭石/(绿泥石+伊利石)(ωk/(ωc+ωl))、化学蚀变指数(CIA)和钾铝质量分数比值(ωK/ωAl)的变化规律进行综合研究,将全新世以来泰国湾古气候演化过程划分为两个阶段:①早中全新世(12000~6500calaBP):ωk/(ωc+ωl)值和CIA 值较高,ωK/ωAl值则较低,指示了该段时期强盛的东亚季风;发生于11200~10500calaBP和8500~7500calaBP的冷事件指示了泰国湾对新仙女木事件和8.2ka冷事件的响应;②中全新世(6500calaBP)以来:ωk/(ωc+ωl)值和 CIA 值明显下降,ωK/ωAl值则逐渐上升,指示了该段时间东亚季风呈逐渐减弱的趋势;在3200~1800calaBP时地球化学和黏土矿物指标呈现一个明显低值,对应于热带海域“斜氏普林虫低值事件”,揭示了全球气候变化在泰国湾海域良好的区域性响应特征。     

Sedimentary environment of Late Carboniferous Tangjiatun Formation in Acheng of Heilongjiang

According to the lithological assemblages and elemental geochemistry of the measured Profile,the authors studied the sedimentary and tectonic environment of the Late Carboniferous Tangjiatun Formation ...     

Chemical weathering intensity and element migration features of the Xiashu loess profile in Zhenjiang, Jiangsu Province

The chemical weathering intensity and element migration features of the Xiashu loess profile in Zhenjiang are studied in this paper. (1) The Xiashu loess profile underwent moderate chemical weathering. It seems that the precipitation is a more important factor than the temperature in controlling the process of the chemical weathering. (2) The major elements such as Si, K, Na, Ca, Mg, Mn and P were migrated and leached, while the elements Fe and Ti were slightly enriched. The migration features of the major elements reveal that the Xiashu loess finished the primary process of chemical weathering characterized by leaching of Ca and Na, and almost reached the secondary process characterized by leaching of K. Except the elements Sr and Ga, other trace elements such as Th, Ba, Cu, Zn, Co, Ni, Cr and V were enriched. It might be caused by both the biogeochemical process and the adsorption of trace elements by clay mineral and organic materials. (3) The difference of element migration down the Xiashu loess profile reveals that the climate was warm and wet at the early-middle stage of the middle Pleistocene. At the end of the middle Pleistocene, it became dry and cool. At the early stage of the Late Pleistocene, the paleoclimate became warm and wet again. As a whole, the paleoclimate generally became drier and cooler in this region from the beginning of the middle Pleistocene.     

Selection and quality assessment of Landsat data for the North American forest dynamics forest history maps of the US

Using the NASA Earth Exchange platform, the North American Forest Dynamics (NAFD) project mapped forest history wall-to-wall, annually for the contiguous US (1986–2010) using the Vegetation Change Tracker algorithm. As with any effort to identify real changes in remotely sensed time-series, data gaps, shifts in seasonality, misregistration, inconsistent radiometry and cloud contamination can be sources of error. We discuss the NAFD image selection and processing stream (NISPS) that was designed to minimize these sources of error. The NISPS image quality assessments highlighted issues with the Landsat archive and metadata including inadequate georegistration, unreliability of the pre-2009 L5 cloud cover assessments algorithm, missing growing-season imagery and paucity of clear views. Assessment maps of Landsat 5–7 image quantities and qualities are presented that offer novel perspectives on the growing-season archive considered for this study. Over 150,000+ Landsat images were considered for the NAFD project. Optimally, one high quality cloud-free image in each year or a total of 12,152 images would be used. However, to accommodate data gaps and cloud/shadow contamination 23,338 images were needed. In 220 specific path-row image years no acceptable images were found resulting in data gaps in the annual national map products.     

面向WebGL的矢量数据三维绘制技术

矢量数据的叠加显示能够提高三维虚拟地球的表达效果与分析能力。受限于GPU的计算精度,在三维虚拟地球中矢量数据绘制普遍存在抖动现象和深度冲突现象。对基于WebGL的矢量数据三维绘制中计算精度问题进行了分析,提出了使用CPU RTC技术和GPU RTE技术提高顶点变换的精度,使用多视锥渲染算法和深度平面技术解决深度缓存精度问题。实验证明,这几种技术和算法可以有效缓解抖动现象和深度冲突现象导致的视觉干扰,改善了各种尺度和范围的矢量数据在三维地形上的叠加显示效果。     

兵棋地图概念模型研究

兵棋地图是对战场环境各要素及其对作战行动影响规律的客观描述,构建兵棋地图概念模型能够促使军事人员和技术人员建立对同一问题的统一认知。首先,分析了军事概念模型的基本概念及其形式化描述方法;其次,提出了战场环境仿真概念模型,据此构建了兵棋地图概念模型,并对概念模型中的两类元素和三种交互关系进行了讨论;最后,利用UML对兵棋地图概念模型进行了形式化描述。     

体素模型的战场环境建模研究

针对基于面模型的战场环境建模难以展现战场环境要素的内部属性和规律等的不足,该文提出了利用体素模型实现战场环境建模的基本方法。该方法能够记录战场环境各要素的不同属性,反映其内部属性和规律,准确地模拟战场地理环境的变换过程,可实现战场环境各要素的统一建模。文章利用体素模型实现了对战场环境的认知与抽象,对战场环境体素数据模型进行了分类。最后以战场地形环境要素为例,利用战场环境基本体元实现了对战场地形环境的体素建模。     

地理国情要素数据成果的一致性检查方法

本文结合全国地理国情要素数据成果过程质量控制、质量复核工作,以及地理国情要素数据成果自身、与地表覆盖分类数据成果、与外业调查核查数据、与专题资料的一致性要求,通过分析检查中发现的质量问题,提出了地理国情要素数据成果的质量控制方法。该方法为国情要素数据成果的质量控制提供了技术参考,为质检工作提供了方法依据。     

Material selection for the gas containment system of a compressed natural gas carrier fleet

In this work, the possible exploitation of fiber-reinforced composites in the context of maritime transportation of compressed natural gas (CNG) is investigated. In addition to a more conventional steel configuration, two different fiber materials, carbon and glass, are considered as construction materials for pressure vessels (PVs) to be stored on board ships, with thickness optimized by FEM analysis.The considered scenario is represented by the transportation of CNG from an offshore well to a terminal on shore. Fleets of ships carrying CNG in pressure vessels manufactured with the investigated materials are generated by means of a ship synthesis model (SSM) software and compared on the basis of technical and economical indicators.The choice of the construction material influences considerably the weight of the PVs, which represent a major item of total ship weight and reflects directly on the general transport performances in terms of resistance, seakeeping and reliability in the service. On the other hand, capital as well as operating expenditures are considerably affected by the choice. When exploring the design space, the ship synthesis model is able, at a preliminary stage of the design, to account for the various technical and economical aspects, their implications and relationships. Results are presented of computations carried out in a specific case, identified by the annual gas production and other characteristics of the well terminal and a cruising route for the ships. The comparison is carried out on the basis of the cost per transported unit of gas and of the percentage of success in the transportation process. The computations show that the choice of the PV material has a key influence on the results in terms of optimal number, dimensions and speed of the ships.     

西太平洋Kocebu海山铁锰结壳稀土元素地球化学特征

西太平洋麦哲伦海山区是全球重要的铁锰结壳资源分布区,具有丰富的稀土元素资源潜力。本文对采自麦哲伦海山区Kocebu海山的11个铁锰结壳表层样（＜1 mm）进行稀土元素地球化学研究,探讨其含量特征、成因和影响稀土元素富集的环境因素。结果表明：Kocebu海山铁锰结壳表层样品ΣREY（Rare earth elements and yttrium）平均含量为1 366 mg/kg,低于前人在麦哲伦海山区其他海山以及邻近的马尔库斯–威克海山区的分析结果;样品轻稀土富集和Ce正异常（平均值为1.45）特征以及稀土元素成因图解、配分曲线和分配系数曲线等均表明该海山结壳属于水成成因;海水中稀土元素含量和溶解氧含量是控制结壳生长的关键环境参数,二者在Kocebu海山所在海区的浅水环境中含量较低;结壳ΣREY含量偏低与采样点水深较浅导致的海水稀土元素含量和溶解氧含量较低密切相关,受碎屑矿物的稀释作用影响较小。在开展铁锰结壳地球化学特征研究和资源勘探评价时应充分考虑采样水深的分布范围,局部水深样品的分析结果可能导致研究结果出现较大偏差。