沂水南小尧金矿锆石U-Pb同位素特征及其地质意义

沂水南小尧金矿产于沂沐断裂带汞丹山凸起上,赋矿围岩为古元古代花岗岩。通过对南小尧金矿矿石中的锆石采用LA—CPMS法进行单颗粒锆石微区U—Pb同位素年龄测定,获得锆石谐和年龄（2438±13）Ma的结果,为赋矿围岩的形成年龄;而下交点（116±20）Ma大致为金矿的形成年龄。结合南小尧金矿石中钾长石矿物K—Ar年龄为（94．29±1．38）Ma的结果分析。本区金矿的形成时代应在早白垩世中-晚期。     

A strip adjustment procedure to mitigate the impact of inaccurate mounting parameters in parallel lidar strips

Lidar (laser scanning) technology has been proven as a prominent technique for the acquisition of high-density and accurate topographic information. Because of systematic errors in the lidar measurements (drifts in the position and orientation information and biases in the mirror angles and ranges) and/or in the parameters relating the system components (mounting parameters), adjacent lidar strips may exhibit discrepancies. Although position and orientation drifts can have a more significant impact, these errors and their impact do not come as a surprise if the quality of the GPS/INS integration process is carefully examined. Therefore, the mounting errors are singled out in this work. The ideal solution for improving the compatibility of neighbouring strips in the presence of errors in the mounting parameters is the implementation of a rigorous calibration procedure. However, such a calibration requires the original observations, which may not be usually available. In this paper, a strip adjustment procedure to improve the compatibility between parallel lidar strips with moderate flight dynamics (for example, acquired by a fixed-wing aircraft) over an area with moderately varying elevation is proposed. The proposed method is similar to the photogrammetric block adjustment of independent models. Instead of point features, planar patches and linear features, which are represented by sets of non-conjugate points, are used for the strip adjustment. The feasibility and the performance of the proposed procedure together with its impact on subsequent activities are illustrated using experimental results from real data.     

Authigenic iron oxide formation in the estuarine mixing zone of the Yangtze River

Estuaries are elementary geochemical fronts where river water and seawater mix. Within this mixing zone, iron and other non-conservative elements can undergo complex reactions to form new solid phases. In order to understand authigenic iron oxide formation in the Yangtze River Estuary, two onsite water-mixing sets of experiments were conducted, one by mixing variable amounts of unfiltered Yangtze River water with filtered East China Sea water of different salinity (set 1), the other by mixing variable amounts of filtered Yangtze River water with filtered East China Sea water of different salinity (set 2). In set 2, the minerals newly formed in the course of mixing were investigated by means of a scanning electron microscope fitted with an energy-dispersive X-ray analytical system. It was found that ferrihydrite and lepidocrocite were formed in these mixing experiments, coexisting in nearly equal amounts. These iron oxides appear as aggregated particles with a large grain-size range of several microns to more than 100 μm. The electrolytic properties of seawater played an important role in the formation of these authigenic iron oxides. Kaolinite and organic aggregates were also found in the experimentally mixed pre-filtered waters. Amounts of newly formed suspended matter (set 2) were one to three orders of magnitude lower than those of total suspended matter (TSM) (set 1). This implies that newly formed minerals represent only a very small proportion of TSM in the estuarine mixing zone of the Yangtze River.     

2009年冬、夏季南海北部超微型浮游生物的分布特征及其环境相关分析

2009年2月(冬季)和8月(夏季)在南海北部海域(nSCS)采用流式细胞术对聚球藻、原绿球藻、超微型光合真核生物3类超微型光合浮游生物和异养浮游细菌的丰度和碳生物量的时空分布特征进行了研究,并分析了其与环境因子之间的关系。结果表明,夏季聚球藻和原绿球藻的平均丰度高于冬季,超微型光合真核生物和异养浮游细菌的丰度反之,为冬季高于夏季。聚球藻、超微型光合真核生物和异养浮游细菌在富营养的近岸陆架海域丰度较高,而原绿球藻高丰度则出现在陆坡开阔海域。在垂直分布上,聚球藻主要分布在跃层以上,跃层以下丰度迅速降低;原绿球藻高丰度主要出现在真光层底部;超微型光合真核生物在水层中的高值同样出现在真光层底部,且与Pico级份叶绿素a浓度分布一致;异养浮游细菌在水体中的分布与聚球藻类似。这些分布格局的差异,取决于环境条件的变化和4类超微型浮游生物生态生理适应性的差异。在超微型光合浮游生物群落中,各类群碳生物量的贡献因季节和海域类型的不同而发生变化:聚球藻在夏季近岸陆架区占超微型光合浮游生物总碳生物量的41%,原绿球藻在陆坡开阔海成为主要贡献者(50%),超微型光合真核生物碳生物量以冬季为高(在近岸陆架区占比68%)。冬、夏季异养浮游细菌碳生物量均高于超微型光合浮游生物碳生物量。     

Pore-water geochemistry in methane-seep sediments of the Makran accretionary wedge off Pakistan: Possible link to subsurface methane hydrate

Cold seeps are pervasive along the continental margin worldwide,and are recognized as hotspots for elemental cycling pathway on Earth.In this study,analyses of pore water geochemical compositions of one-400 cm piston core(S3) and the application of a mass balance model are conducted to assess methane-associated biogeochemical reactions and uncover the relationship of methane in shallow sediment with gas hydrate reservoir at the Makran accretionary wedge off Pakistan.The results revealed that approximately 77% of sulfate is consumed by the predominant biogeochemical process of anaerobic oxidation of methane.However,the estimated sulfate-methane interface depth is-400 cm below sea floor with the methane diffusive flux of 0.039 mol/(m~2·a),suggesting the activity of methane seepage.Based on the δ~(13)C_(DIC) mass balance model combined with the contribution proportion of different dissolved inorganic carbon sources,this study calculated the δ~(13)C of the exogenous methane to be-57.9‰,indicating that the exogenous methane may be a mixture source,including thermogenic and biogenic methane.The study of pore water geochemistry at Makran accretionary wedge off Pakistan may have considerable implications for understanding the specific details on the dynamics of methane in cold seeps and provide important evidence for the potential occurrence of subsurface gas hydrate in this area.     

p-y曲线对成层土体中大直径单桩的适用性研究

API规范推荐的p-y曲线是由均质土体得到的,并未考虑土层间相互作用,Georgiadis基于柔性桩提出了等效深度法修正p-y曲线,把均质土p-y曲线延伸到了成层土体中。为了研究p-y曲线和等效深度法对于大直径单桩在成层土体中的适用性,取4种典型地质条件:成层砂土、砂土-黏土-砂土、成层黏土和黏土-砂土-黏土,通过L-PILE软件计算了6 m直径单桩基础的p-y曲线、桩顶水平荷载-位移曲线、桩身位移和弯矩。并与ABAQUS建立的单桩基础三维有限元模型计算结果进行比较。结果表明等效深度法对于成层砂土影响不大;对于成层黏土影响较大;对于中间为软弱土层的成层土体,在荷载较大时影响显著,等效深度法计算结果更加接近FEM结果。在成层土体中,p-y曲线应用于大直径单桩对于砂土高估了初始刚度,低估了极限抗力;对于黏土则低估了初始刚度和极限抗力。     

AUV矢量推进水动力计算及水平回转操纵性试验

针对矢量推进模式下的 AUV 水动力性能和操纵性能,开展了 AUV 矢量推进水动力 CFD 计算, 对矢量推进水平回转操纵性进行了评估,加工了矢量推进样机,并进行湖上操纵性验证。理论计算和试验数据表明：矢量推进具备极高的低速操纵性,该研究为矢量推进在 AUV 上的应用提供了理论和技术基础。     

基于GIS的建筑施工管理信息系统的研究与应用

GIS技术应用于工业民用建筑施工管理信息系统,对于提高施工管理效率,控制施工进度,检验施工质量,节省施工费用等,都显示出了传统的手工管理模式无法比拟的优点,同时能为施工设计人员以及领导决策提供直观的图形显示和分析统计的功能,真正达到施工设计和管理的科学化和规范化。系统将施工过程中的进度、质量、成本、测量作为系统管理的重点,设计了11个子系统,涵盖了大量的空间和属性信息,内容丰富,适应性强。     

Extension of high-order harmonics and generation of an isolated attosecond pulse in the chirped laser field

This paper theoretically investigates the high-order harmonic generation cutoff extension using intense few-cycle linearly chirped laser pulses. It shows that the cutoff of the harmonic can be extended remarkably by optimising the chirping parameters. The time-frequency characteristics of high-order harmonics with different chirping parameters are analysed by means of wavelet transform of the dipole acceleration. It also gives out the classical three-step model pictures of electron. By superposing a properly selected range of the harmonic spectrum, it obtains an isolated 65as pulse.     

1987—2018年西双版纳橡胶林时空变化及其线状特征

基于1987—2018年西双版纳30 m分辨率橡胶林数据集,利用叠置、缓冲区等GIS空间分析方法,对比分析了过去32年橡胶林沿道路、河流和边境线的空间变化特征与区域差异。结果表明：1) 1987—2018年,西双版纳橡胶种植面积在道路、河流沿线5 km以内分别增加了1 874.6和1 484.6 km²,在边境地区(国境线20km缓冲带)增加了1 393.1 km²。2)从道路沿线看,受橡胶种植可达性和交通运输影响,过去32年道路5 km缓冲带内的橡胶林平均占比超过九成。3)从河流沿线看,因灌溉和水源等需求,过去32年河流沿线5 km缓冲带内橡胶林平均占比69.7%。值得注意的是,受天然橡胶价格持续低迷、城镇化与生态环境保护等影响,2010年河流沿线橡胶林种植面积开始下降,沿线2 km内表现尤为显著。4)从边境地区看,西双版纳橡胶林种植呈明显趋边性特征,跨境种植频繁。过去32年边境沿线地区橡胶林平均占比55.6%,且由1987年的35.4%上升到2018年的66.2%,其中,在中缅边境的扩张面积和速率高于中老边境。