基于ArcGIS Objects的带状图生成算法研究

带状图具有折点难处理、生成算法复杂等特点,是城市地下管线信息系统建设的难点之一。本文提出了一种通过计算带状图图幅顶点坐标以生成带状图的方法,并对折线、折点处理进行了重点阐述,简单介绍了带状图的打印出图,最后利用ArcGIS Object平台与C#编程实现了地下管线数据带状图生成的实验验证。     

华东南地区5.5级以上地震前的地震活动图像异常研究

对华东南地区1970年以来5.5级以上地震前的地震活动空间图像进行了分析, 发现震前多有不同程度的地震条带、 空区或增强异常出现。 所研究的9次地震中, 有4次震前出现了地震条带异常, 3次出现了地震空区异常, 4次出现了地震活动增强, 出现2种以上异常的地震有4次。 条带、 空区与主震的相对位置表明, 主震发生在条带内部的比例与边缘及外侧相当, 主震全部发生在空区内部。 条带、 空区相对于发震断层走向的角差小于30°的比例分别为33%和60%。     

露天矿采场时空数据模型的构建与应用

以地理信息系统技术为核心,建立露天矿采场时空数据库,通过构建采场的时空数据库,动态描述露天矿生产的剥、采、排过程,为露天开采的规划、设计、生产调度管理的优化预控决策提供全方位的空间信息支持。提出考虑台阶特征的不规则三角网（TIN）的露天矿采场三维建模理论与方法,采用基于基态修正和时间快照模型构建露天矿采场时空数据库,通过地理信息系统和虚拟现实技术,实现开采过程的回放和生产计划的超前演示,为数字露天矿建设构建基础的地理空间信息框架与平台。     

基于地形频谱分析提高多波束条带拼接效果应用

针对多波束测深系统条带拼接中的系统性残差问题,提出基于地形频谱分析的方法来削弱系统性残余误差的影响。该方法相对于传统的拼接方法,无需进行相邻条带ping(激发)连续匹配,避免ping误匹配所产生的地形长波项不符的问题,并且所采用的多面函数不仅可获得所测条带的重叠区长波项信号,还可获得非重叠区的拟合信号。结果表明,采用地形频谱分析法所处理后,多波束测深数据残余误差的影响得到了显著的削弱,拼接精度显著提升。     

带状数字线划图（DLG）坐标转换方法研究

带状地形图狭长,带状数字线划图坐标转换涉及坐标转换参数和接边问题。本文采用多项式拟合法和分区块重叠带,确定区块坐标转换参数,实现了带状数字线划图坐标转换,解决了分区图形坐标转换的接边问题。并采用实测带状数字线划图数据进行坐标转换实验,转换精度高,能够满足大比例尺带状数字线划图坐标转换要求。     

Mechanical responses of metallic strip flexible pipes subjected to pure torsion

Metallic strip flexible pipes (MSFP), a relatively new style of unbonded flexible pipes, are considered as an attractive alternative to traditional submarine pipes. Pipelines will inevitably confront torsion load which may affect the integrity and safety during their installation and application. Throughout this paper, the mechanical behavior of MSFP subjected to pure torsion is investigated by both experimental and numerical methods. Results from these two methods are essentially in agreement with each other. The finite element method (FEM) can be adopted to predict the failure torque of MSFP under torsion and analyze the detailed stress conditions of each layer. In addition, the effects of boundary conditions, layout manners of steel strips, friction coefficients between contact surfaces, twist directions and tension loads are discussed. The obtained conclusions will benefit cross-section design of MSFP and relative practical engineering.     

顶部条形基础作用下加筋挡墙性能的试验研究

针对加筋挡墙顶部受条形基础载荷作用时的工作性能开展试验研究,分析条形基础距挡墙面板距离对基础极限承载力、加筋挡墙变形特点、筋材应变和破坏模式的影响。试验结果表明：基础极限承载力随基础偏移距离 增加呈现先增大后减小的趋势,且在 为 （ 为挡墙高度）时达到最大值;条形基础加载至破坏前一级载荷时,基础沉降与挡墙高度比值均小于2%,面板水平位移与挡墙高度比值均小于1%,且当 小于0.6时,面板顶部水平位移明显大于中底部;各层筋材中应变最大值随 增加而逐渐向远离面板方向发展,且筋材最大应变由最初出现在顶层而转向中间层;顶部受条形基础载荷作用下加筋挡墙破坏以3种模式为主,即顶层面板挤出的浅层破坏、破坏面沿基础边缘发展并向深部推进和加筋挡墙整体破坏。     

基于GNSS浮标的海岛礁稀少控制DOM生产技术

针对远海岛礁多为不可登岛,开展远海岛礁大比例尺测图难度大的问题,该文提出了利用GNSS浮标作为海上控制点,探讨GNSS浮标在海岛礁1∶2 000DOM生产中发挥的作用。采用长航时无人机获取试验岛礁高分辨率影像,在无人机常规航线并加摄构架航线的前提下,结合PPP技术,在海岛四周布设GNSS浮标的控制组合方式进行区域网平差和影像生产。试验结果表明,利用此种方法进行远海岛礁大比例尺DOM生产是切实可行的,精度基本满足海岛1∶2 000DOM生产精度要求,研究成果为远海岛礁1∶2 000DOM生产提供了一套合理的解决方案,为远海岛礁大比例尺测图提供参考。     

Modelling flow and sediment trapping upstream and within grass buffer strips

Grass buffer strips impact the hydrology of flow and consequently the fate of sediment. A complex process‐based model is developed to predict flow characteristics as well as sediment deposition and transport upstream, and within grass strips. The model is capable of estimating the proportion and amount of different sediment particle size classes in the outflow. The modified Green–Ampt equation was used to simulate infiltration. Gradually varied flow and kinematic wave approximation were used to model flow characteristics upstream and within grass strips. The GUEST model approach has been modified in order to use its basic approaches in sediment transport module in grass strips. Model predictions agree well with the results of two sets of controlled experiments. The bias, coefficient of model efficiency and the root mean squared error of the modelled efficiency of grass strips in reducing sediment concentration were 0.93–0.99, 0.58–0.99 and 8.9–12.7, respectively. The sensitivity analysis showed that the initial soil moisture and flow rate are the most sensitive parameters in predicting runoff loss. Increasing the slope steepness and flow rate dramatically decreases the efficiency of grass strips in reducing sediment concentration and mass. Copyright © 2015 John Wiley & Sons, Ltd.     

机载LiDAR点云时间纹理信息航带重叠区消冗

机载LiDAR获取的完整测区点云数据中包含了丰富的信息,同时也伴随着大量冗余数据,本文提出基于机载LiDAR点云时间纹理信息的航带重叠区消冗方法。首先按点云时间信息划分航带,再按点云纹理信息提取航带边缘,接着提取高地物遮挡空洞,最后去除重叠区冗余数据。实验结果表明,该方法无需航线信息辅助,并能在保留遮挡空洞区域点云的同时,高效地去除航带重叠区中精度较低的点云。