应用测距三角高程法进行跨河水准测量

为将三角高程法跨河水准测量的技术规范要求对应到工程案例中,有效指导技术人员实际操作,本文通过工程实例,按测距三角高程法跨河水准测量的作业流程、计算公式、各未知数据求值展开,逐层解构分析,细致阐述跨河水准测量中测距三角高程法的要点,实例验证了利用测距三角高程测量实现二等跨河水准测量的可行性。同时对“跨河垂直角观测时视线长”的简易计算公式进行了推导,探讨了计算结果的准确性和有效性,对跨河二等水准测量具有较好的推广价值。     

单向三角高程测量在大坝变形监测中的应用

简述了单向三角高程测量原理,通过相关项目的应用论述了单向三角高程测量的可行性,再利用项目实例,论证了利用高精度的测量仪器通过单向三角高程测量进行大坝垂直变形监测是成功的。该方法减轻了常规的水准测量或静力水准测量的劳动强度,节约了成本,提高劳动效率,可作为后期项目的借鉴。     

三角高程测量在基坑监测中的研究及应用

采用一种新的三角高程测量方法进行变形监测,该方法可以使全站仪在任意点设站,减少了工作量,在测量中,不用量取仪器高、棱镜高,减少了三角高程测量中的误差来源,提高了精度。通过分析三角高程测量的精度,验证了精密三角高程测量代替几何水准测量的可行性与可靠性,结合基坑监测实例,将三角高程测量的数据与几何水准测量的数据进行比较,比较的结果显示,该三角测量方法结合精密全站仪可以替代几何水准测量,在实际工作中具有一定的适用性和参考价值。     

高原地区精密三角高程测量实践

简要介绍了精密三角高程测量的原理及方法;结合"青海省藏区现代测绘基准体系基础设施建设"兴海至同德二等水准测量项目,介绍了测区具体的测量条件,提出了在高原地区进行精密三角高程测量需采取的措施。通过分析测量结果,证明了精密三角高程测量代替二等几何水准测量在高原地区的可行性。     

井下三角高程代替水准测量的可行性

通过对全站仪三角高程测量精度的分析,论证了井下三角高程测量可以作为井下高程控制的一种手段。并通过一些三角高程测量在实际矿山测量中的应用实例,验证了利用全站仪三角高程测量代替井下水准测量实施井下高程控制的可行性结论。     

基于精密三角高程测量的基坑变形监测方法研究

传统的基坑监测中,几何水准测量工作效率低,任务量大。针对这些不足,本文采用一种新的三角高程测量方法进行变形监测,该方法可以使全站仪在任意点设站,减少了工作量,在测量中,不用量取仪器高、棱镜高,减少了三角高程测量中的误差来源,提高了精度。通过分析三角高程测量的精度,验证了精密三角高程测量代替几何水准测量的可行性与可靠性,结合基坑监测实例,将三角高程测量的数据与几何水准测量的数据进行比较．比较的结果显示,该三角测量方法结合精密全站仪可以替代几何水准测量,在实际工作中具有一定的适用性和参考价值。     

精密三角高程在长距离一等跨河水准测量中的应用

通过分析长距离跨河水准测量的高差计算模型,针对三角高程测量中各精度影响因素制定合理的施测方案,并通过工程实例予以可行性验证。结果表明:采用高精度仪器、特制的觇灯,并遵循科学的观测方法,能够有效减弱垂直角观测及大气折光对三角高程测量精度的影响,并使其满足长距离跨河水准测量的精度要求。     

中间法电磁波测距三角高程代替精密水准测量的研究

本文在简要介绍中间法电磁波测距三角高程测量原理基础上,推导了高差计算及精度估算公式;分析了中间法测量代替精密水准测量的必要条件、重要条件和次要条件。通过大量实测数据对比分析,验证了中间法测量代替精密水准测量的可行性,最后给出了中间法测量的实施方案。     

精密三角高程代替二等水准实现跨河水准测量的研究与应用

本文对精密三角高程测量的理论与方法、误差来源及精度指标进行了分析研究，探讨了其代替二等水准进行跨河水准测量的可行性及关键问题，提出了采用两台高精度自动照准全站仪对向观测进行跨河水准测量的具体操作方法及要求，并在重庆轨道交通环线建设中进行了多次应用，证明了精密三角高程测量在一定条件下能够满足二等水准测量的精度要求，具有较高的经济效益。     

单标三角高程法跨河水准测量设计与实验分析

针对现行规范中2 km以上距离的三角高程法跨河水准测量应采用双觇板的规定,进行了单标三角高程法跨河水准测量的观测设计,并通过实验与双标三角高程法及已知高差进行比较分析。结果表明:单标三角高程法可用于2 km以上距离的跨河水准测量,其半测回中的垂直角观测组数宜增至双标法的2倍。     

光电测距三角高程测量在山区代替三,四等水准的可行性探讨

本文作者根据自己在工作实践中的尝试，对在山区用光电测距三角高程测量代替三、四等水准问题，谈了几点体会．     

三角高程法超长距离跨海高程传递实验研究

针对三角高程法跨海高程传递测量误差的来源问题,该文提出了基于三角高程法的超长距离跨海高程传递方法,设计了具体的测量方案,包括跨海场地选定与布设,观测标灯设计与制作,跨海观测时段数、测回数及组数设计,观测程序与观测方法、观测成果的限差验算与成果取舍等,并提出了跨海高程传递精度评定的两种方法。在平潭海峡公铁两用大桥工程现场选定两条跨海线进行了实验研究,实验结果表明,13.9km和18.0km跨距的跨海高差平差值与已知高差的较差均小于二等水准测量限差,每千米跨海高程测量中数的中误差分别为±0.68mm和±0.63mm。     

FORMULAE FOR THE ADJUSTMENT OF SURVEY ERRORS

Abstract

The formulae given in this paper can be used for a station adjustment at a trigonometric station and also for the adjustment of errors in a level survey. As applied to levelling, the problem consists in finding the most probable values of the reduced levels of a number of points where the observed level differences between the points are not consistent with each other. It can be shown that the required values of the reduced levels are those which reduce the sum of the squares of the residual errors to a minimum, where the residual error is defined as the difference between the calculated and observed levels.     

Curvature correction in electronic distance measurement

The usual methods for curvature correction, which consist of a geometric and a velocity component, are based on standard atmospheric conditions and thus take no account of variable refraction. A formula has been developed expressing the correction as a function of atmospheric refraction: K=(1-k_² S²/(24 R²) whereS is the measured distance, R is the radius of the earth, and k is the coefficient of refraction. This formula leads to a practical procedure employing trigonometric levelling in the determination of curvature correction for long-range geodimeter measurements.     

基于三角高程对向观测法闭合差的偶然误差检验研究

在三角高程对向观测法理论的基础上,根据对向观测法的闭合差条件,提出其偶然误差特性的检验,并结合数例进行包括闭合差正负号检验、正负误差分配顺序检验、误差数值和的检验和个别误差值的检验.最后得出三角高程对向观测法闭合差具有偶然误差特性,并具有一定的正确性和现实指导意义.     

精密三角高程测量严密计算的理论研究与初步实验

本文根据水准面、似大地水准面、参考椭球面、高程异常、垂线偏差与正常高之间的关系，推导出了新的普通三角高程测量及光电测距三角高程测量的精密计算公式，并对新公式进行了初步的实验验证。     

电磁波测距三角高程代替四等水准的精度分析

对电磁波三角高程测量的误差进行了详细讨论,模拟数据表明,高差中误差主要取决于测角精度、视线长度和仪器高量测精度。对测角中误差为1″或更高测角精度的仪器,使用对向观测的方法,可用三角高程测量可代替四等水准测量。     

Efficient interpolations to GPS orbits for precise wide area applications

For precise real time or near real time differential GPS positioning in a wide or global area, precise GPS orbits or, alternatively, precise orbital corrections with respect to a reference orbit, such as GPS broadcast ephemerides, must be used. This work tests orbit interpolation methods, in order to represent the GPS orbits and orbital corrections accurately and efficiently for these and other GPS applications. For precise GPS orbits given in the SP3 format at the 15 min interval, numerical tests were conducted using Lagrange and Chebyshev as well as trigonometric polynomial functions. The results have demonstrated that the 19- or 20-term trigonometric function is apparently the most efficient interpolator for a 12 h GPS orbital arc, achieving 1 cm level 3D interpolation accuracy that can meet the requirements of most precise applications. The test results also demonstrated that the 9-term trigonometric function always yields optimal interpolation for a 2 h GPS orbit arc, in terms of interpolation errors, compared to the results when using a different number of terms for the same function or one of the other tested polynomial functions. This is evident from the minimal performance degradation when using the 9-term trigonometric function to interpolate near or at the end of a data interval. By limiting interpolation to the center 15 min to 1.5 h of a 2 h orbit arc, thereby eliminating the need to interpolate near the ends of that interval, users can opt for more terms (11 and 13) or different interpolators to further improve interpolation accuracy. When interpolating the orbital corrections with respect to the GPS broadcast ephemeris, all the tested interpolation functions of 3- to 9-term yield the same suitably accurate results. Therefore, a 3- to 5-term trigonometric function is arguably sufficiently accurate and more efficient for GPS orbital correction messaging in wide area and real time positioning.     

Modelling local GPS/levelling geoid undulations using artificial neural networks

The use of GPS for establishing height control in an area where levelling data are available can involve the so-called GPS/levelling technique. Modelling of the GPS/levelling geoid undulations has usually been carried out using polynomial surface fitting, least-squares collocation (LSC) and finite-element methods. Artificial neural networks (ANNs) have recently been used for many investigations, and proven to be effective in solving complex problems represented by noisy and missing data. In this study, a feed-forward ANN structure, learning the characteristics of the training data through the back-propagation algorithm, is employed to model the local GPS/levelling geoid surface. The GPS/levelling geoid undulations for Istanbul, Turkey, were estimated from GPS and precise levelling measurements obtained during a field study in the period 1998–99. The results are compared to those produced by two well-known conventional methods, namely polynomial fitting and LSC, in terms of root mean square error (RMSE) that ranged from 3.97 to 5.73 cm. The results show that ANNs can produce results that are comparable to polynomial fitting and LSC. The main advantage of the ANN-based surfaces seems to be the low deviations from the GPS/levelling data surface, which is particularly important for distorted levelling networks.