大型斜拉桥缆索管精密定位的研究

结合现代大型斜拉桥的施工测量实践，阐述了斜拉桥的大型构件──缆索管精密定位的原理和方法，分析了缆索管的定位精度与质量，指出了为保证缆索管的定位质量，设计和施工中值得改进的问题。     

可变形网络与迁移学习相结合的电力塔遥感影像目标检测法

电力塔是电力基础设施的重要组成部分,对其进行检测是必不可少的工作。针对当前遥感影像电力塔检测算法精度低,效果差的问题,本文基于可变形网络和迁移学习对Faster R-CNN进行改进,提出一种基于遥感影像的电力塔检测框架。该框架主要分为两个部分:①特征提取子网络,即利用可变形网络模型改进卷积层,来提高模型对于电力塔几何形变的特征提取能力;②目标检测子网络,即通过模型迁移,将由特征提取子网络训练获得的模型参数迁移至此子网络,由RPN网络和可变形区域池化结合非极大值抑制(NMS)精确获取电力塔位置,利用Fine-tuning技术快速训练此子网络,最终实现高精度的遥感影像电力塔检测。本文算法在测试集中对电力塔检测结果为AP_(0.5) 0.886 1,AP_(0.6) 0.839 6,ACC 0.894 8,与SSD、YOLOv3、Faster R-CNN等相比,各检测指标至少高0.2。由对比试验可以看出,该框架对电力塔遥感影像可以实现较高精度检测,表明该方法在电力塔检测上拥有较大应用潜力。     

机载激光点云中高压电塔自动识别方法

提出了一种基于格网特征的机载激光点云高压电塔自动识别方法。首先对机载激光点云数据进行滤波去噪处理；然后对点云数据进行规则格网化特征分析获得高压电塔粗识别区域；最后对粗识别区域进行外接邻域网格线性特征悬空点集检测以确定电塔识别结果，并以分层切片法分析获取电塔平面中心坐标。采用大型无人机实际线路巡检获取的机载点云数据对本文算法进行验证，试验结果表明本算法可实现高压电塔的快速自动识别，对无人机电力巡检智能诊断具有一定的促进作用。     

通过控制点布设探究航测精度

航测数字化生产的数字地形图,其质量和精度是非常重要的。利用摄影测量的方法测图,需要一定数量的像片控制点,而控制点的布设,是影响航测精度的重要因素,测区内控制点立体、均匀地分布,及避开山谷、建筑物和电磁波干扰等因素,均有利于提高航测精度。     

悬索桥主缆架设测量方法与误差修正

分析了悬索桥主缆架设测量的主要误差来源,提出了几种相应的改进方法。在主缆基准索股架设测量过程中,综合考虑测量误差,采取反推仪器高法修正仪器高量取误差;垂度测量时,采用上下安装棱镜的夹具工装,即通过测上下棱镜的标高,取其平均值推算出基准索股垂度;一般索股采用改进的相对基准索股法进行测量调整。上述方法在实际应用中获得了较好的结果,能满足主缆架设测量的精度要求,可供类似桥梁工程借鉴。     

CCTV新台址主楼变形监测分析

以钢结构为主体的CCTV新台址的主楼造型独特,两塔楼双向向内倾斜6°,顶部外挑形成14层的＂L＂形悬臂。施工过程中,塔楼自重、温度等外界因素引起的变形对钢结构的安装质量有着重要的影响,决定着结构稳定后的最终状态。针对这一特殊结构,分析塔楼施工过程中的变形因素,介绍利用测量机器人进行塔楼变形监测的过程,并研究变形和施工进度的关系、以及日照作用引起的周日变形,其结果可为悬臂安装质量的控制提供技术依据。     

高速滑轨控制测量网的建立及精度评估

针对火箭滑橇轨道准直度精密测量任务,该文分析了工程建设初期利用传统控制网布设方案存在的缺陷与不足,并提出了三级轨道控制网设计思想。首先选择高精度的一级控制网点,然后将控制网由原来的直线等距布设调整为面域均匀布设,最后将控制网布设方式由直线布设调整为东西对称布设,建立了高速轨道平面控制网的精度估算模型,分析了优化控制网的网点精度。结果表明:改进布网方式能够较好地实现对横、纵两个方向的精度控制。     

CCTV新台址主楼的倾斜变形特性研究

CCTV新台址主楼的塔楼双向倾斜6°,在自重恒荷载作用下,塔楼向倾斜方向变形。倾斜变形影响测量基准垂直传递的稳定性,导致施工测量存在系统偏差。文中介绍基于测量机器人的塔楼倾斜变形监测过程,分析倾斜变形规律,利用最小二乘拟合法求得塔楼的日变形速度,并根据测量基准垂直传递的限差,通过误差传播定律,确定测量基准合理的检核频率,保证了塔楼的施工测量质量,也可为其它类似的高层建筑施工提供参考。     

A new method for precise astro-azimuths

The theodolite used in this method is completely leveled by using autocollimation from a free mercury surface. This eliminates the need for striding or hanging levels which are in conventional use to level the trunion axis of the theodolite. Mercury leveling is more accurate and can be performed in a much shorter time than leveling by the striding or hanging levels. In addition, this new method removes the unavoidable axis wobbles contaminating the observed horizontal angles between the star and the azimuth mark. The uncontrolled wobble errors affecting azimuths can be up to three arc seconds. The axis wobbles are removed by using autocollimation from an axis mirror which is perpendicular to the trunnion axis of the theodolite. Autocollimation coincidences from the mercury and from the axis mirror can be made within one or two tenths of an arcsecond. This new method and instrumentation surpasses the obtainable precision by the conventional first-order astro azimuth observations by reducing the unknown systematic wobble and level errors by one order of magnitude.     

转台几何参数测量的实践

探讨了转台几何参数的测试方法，确定了通过让旋转轴转起来、测量与旋转轴对应的点来复现旋转轴进而计算其参数的测试思路，采用了由电子经纬仪构成的工业测量系统，方便快捷，精度较高，结果可靠。     

Digital Surface Development of Large Cylindrical and Conical Structures With a Single-Image Technique

Normally, regular surfaces of architectural or archaeological interest can be accurately mapped with single-image techniques. Whenever possible, such surfaces are developed digitally, or they are presented as suitable cartographic projections. This paper describes the raster development of two large towers, one conical and one cylindrical, with heights of 19m and 12 m, and diameters of approximately 10m and 8m, respectively. The towers, dating from circa 300 BC, are situated on Greek islands and are accessible only on foot. The first tower was imaged from its surrounding hills with several lenses, including powerful telephoto lenses. The other tower was recorded from up to 9m above ground level by means of a modified fishing rod carrying a lightweight 35mm camera. All the non-metric photographs, taken at a negative scale of approximately 1:350 which allowed an overall accuracy of 3 cm to 4 cm to be achieved, were developed digitally and then mosaicked. The raster products are described and discussed.     

Monitoring global land surface drought based on a hybrid evapotranspiration model

The latent heat of evapotranspiration (ET) plays an important role in the assessment of drought severity as one sensitive indicator of land drought status. A simple and accurate method of estimating global ET for the monitoring of global land surface droughts from remote sensing data is essential. The objective of this research is to develop a hybrid ET model by introducing empirical coefficients based on a simple linear two-source land ET model, and to then use this model to calculate the Evaporative Drought Index (EDI) based on the actual estimated ET and the potential ET in order to characterize global surface drought conditions. This is done using the Global Energy and Water Cycle Experiment (GEWEX) Surface Radiation Budget (SRB) products, AVHRR-NDVI products from the Global Inventory Modeling and Mapping Studies (GIMMS) group, and National Centers for Environmental Prediction Reanalysis-2 (NCEP-2) datasets. We randomly divided 22 flux towers into two groups and performed a series of cross-validations using ground measurements collected from the corresponding flux towers. The validation results from the second group of flux towers using the data from the first group for calibration show that the daily bias varies from −6.72 W/m² to 12.95 W/m² and the average monthly bias is −1.73 W/m². Similarly, the validation results of the first group of flux towers using data from second group for calibration show that the daily bias varies from −12.91 W/m² to 10.26 W/m² and the average monthly bias is −3.59 W/m². To evaluate the reliability of the hybrid ET model on a global scale, we compared the estimated ET from the GEWEX, AVHRR-GIMMS-NDVI, and NECP-2 datasets with the latent heat flux from the Global Soil Wetness Project-2 (GSWP-2) datasets. We found both of them to be in good agreement, which further supports the validity of our model's global ET estimation. Significantly, the patterns of monthly EDI anomalies have a good spatial and temporal correlation with the Palmer Drought Severity Index (PDSI) anomalies from January 1984 to December 2002, which indicates that the method can be used to accurately monitor long-term global land surface drought.     

Ground movements caused by deep underground mining in Guan-Zhuang iron mine,Luzhong, China

It is difficult to calculate the accurate ground movement due to deep underground mining because of the complexity of the geotechnical environment. Guan-Zhuang iron mine is a pillarless sublevel caving mine operated by Luzhong Metallurgical Mining Company, south-east of Jinan, PR China. It mines the Zhangjiawa Seam at a depth of approximately 520 m. Although the towers are outside the conventional ‘angle of draw’ subsidence influence criteria, and have seen only negligible vertical displacement as a result of deep mining, there has been widespread evidence of regional horizontal displacement of the land surface, large distances away from the mining area. Possible explanations of these displacements include one or a combination of mechanisms such as pre-mining stress relaxation, regional joint patterns, soft rock strata, displacement toward active goaf areas. Luzhong Metallurgical Mining Company have been making precise measurements of distances near the shaft towers in the Guan-Zhuang iron mine since 2003. The results show horizontal displacements of up to 96 mm occur even when underground mining is about 0.8 km from the survey displacements. From an analysis of these and other survey results it is concluded that mining effects extend a long way from deep mining. The results also show that ground horizontal displacements are typically at least as great as the vertical component, that the maximum horizontal displacement occurs soon after undermining.     

基于飞机场特殊高边坡填筑施工放样

填筑的高边坡不平行于飞机杨跑道纵轴线,由于有两个坡比,给施工放样样找点带来困难.建立空间平面方程,计算坡顶线的法向线坡比,编程计算施工放样,这种方法的效果是较明显的,工作简单、便捷、高效,放样数据计数准确、可靠.     

雷达卫星影像中输电导线散射斑的相位时间序列稳定性分析

分析输电导线散射斑相位的几何关系,选取20幅时间跨度约为1年的TerraSAR条带模式影像,对其中两基铁塔之间6条输电导线形成的散射斑相位时间序列进行分析。文中统计分析构成导线散射斑像元的相位离散度,其标准差约为0.2弧度,表明单个散射斑相位稳定。选取铁塔顶部点的导线散射斑为参考点,与另外5个导线散射斑做差分相位时间序列分析,分析导线之间高程差的理论计算值与实际值的一致性。分析结果显示,导线散射斑差分相位序列的波动可达2弧度以上,与导线间高程差产生的相位不一致。     

基于正弦拟合的三轴磁力仪标定方法

三轴磁力仪是一种常用的磁场测量工具，在地磁导航、海洋磁测、地磁勘探等领域应用较为广泛。作为一种磁场矢量测量工具，三轴磁力仪的磁测误差主要来源于三轴非正交、敏感轴灵敏度不一致及零偏误差等方面，磁力仪的标定优劣影响磁力仪的测量性能。为解决三轴磁力仪的标定问题，建立了磁力仪误差补偿模型，提出了基于正弦拟合的三轴磁力仪标定方法。将磁力仪沿平面旋转时的三轴输出数据拟合成正弦曲线，利用正弦曲线的幅值、初相角和平移量等信息计算出磁力仪的标定参数。仿真结果表明:该方法无需非线性优化过程即可实现标定参数的求解，得到的标定参数与设定值吻合度高；磁测噪声对三轴灵敏度系数及非正交角的计算结果影响较小。     

利用GPS定位技术建立沛县地籍测量控制网

随着GPS定位技术的快速发展，GPS定位技术在工程测量领域的应用越来越广泛，从控制测量、地形测图，到施工放样都发挥了重要的作用。本文主要叙述了利用GPS定位技术建立沛县地籍控制网的情况。     

具有孔洞的地下电缆工井模型拓扑重构研究

城市地下电缆工井是发挥城市功能和确保城市快速协调发展的重要基础设施，但地下管线结构复杂、信息量大，对其进行三维显示、管理与分析具有一定的难度。激光雷达技术出现后，因其快速、不接触、高密度、高精度等特征，被逐步应用于建筑物逆向重建，基于激光雷达点云数据的地下电缆工井三维重建也逐渐成为主流方法。提出了一种针对具有孔洞的地下工井的三维模型拓扑重构算法，以地下工井三维激光点云为数据源，建立具有孔洞的地下工井三维模型，可解决直接采用点云进行构网时模型不完整及速度较慢的问题。三维模型的构建采用与常用的管线化地下管网结构不同的CSG-BREP（constructive solid geometry-boundaryrepresentation）拓扑模型结构，整体上将工井分为墙面、电缆、井筒等，此模型可更加细致地表达地下电缆工井模型的内部拓扑结构。实验证明，该算法可以对多种类型的墙壁进行拓扑重构，在表达模型拓扑关系时突破了传统管网中单一的管孔与管线的点线关系及管线间的线线关系，增加管孔与墙壁的点面关系以及管线与墙壁的线面关系，更加细致准确地对模型进行描述。     

Ashtech扼流圈天线相位中心稳定性的检验

接收机天线相位偏差是GPS定位中一项重要的误差源，其影响值可达数毫米至数厘米，为了解接收机天线性能及稳定性等方面的情况，在出测前后一般对相位中心的稳定性进行检验。目前已采用两种方法对Ashtech扼流圈天线相位中心稳定性进行了测试，证明了AshtechZ-12型接收机天线满足限差要求及试验方法的可行性，本文将就此作具体介绍。     

无定向点优化布局的多边交会测量精度分析

多边交会系统利于提高激光跟踪仪坐标测量精度,但测量精度易受测站布局和系统参数标定精度的影响。引入球心拟合的无定向点系统参数标定法,避免传统系统参数标定精度受定向点分布的影响,根据无定向点系统参数标定模型推导出多边交会的最佳测站布局——直角正三棱锥,从而保证多边交会测量精度。仿真结果表明,在5 m范围内,球心拟合的无定向点系统参数标定中误差为0.006 4 mm,最佳测站布局下多边交会的点位中误差为0.005 mm。经标准尺长度测量验证和四面体标准器坐标测量验证,优化后多边交会的长度测量中误差为0.003 6 mm,坐标测量中误差为0.005 3 mm。在无定向点系统参数标定和直角三棱锥布局下,激光跟踪仪多边交会能够实现微米级三维坐标测量。