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排序方式: 共有498条查询结果,搜索用时 15 毫秒
51.
VLBI、SLR、GPS综合数据处理方案研究 总被引:1,自引:0,他引:1
按参与平差观测值类型的选取不同,对VLBI、SLR、GPS综合处理方案进行了分类。给出了各类方案的平差模型,结合当前我国三种技术的实测情况,分析了各种方案的优缺点,提出了较为可行的综合处理方案。 相似文献
52.
53.
Robust估计的算法优化 总被引:2,自引:0,他引:2
本文分析了Robust估计收敛慢的原因,提出以最小二乘平差的残差(V)为初始信息,用L1估计的权函数所计算的权力初始权,根据迭代计算的残差的大小,及残差的变化所提供的信息,构造出加速收敛的算法,计算结果表明,较之一般的方法,迭代次数显著减少,辨识杠杆点含粗差的能力有较大提高,即搜索粗差的效率有很大提高。 相似文献
54.
55.
仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了低纬子午环的观测原理和仪器结构,系统地探讨了它的各种仪器误差的来源、测定和处理方法。为了进一步完善采用组合固定角距法测定对径改正的方法,在第三章,研究了提高对径改正测量精度的方法,重新推导了对径改正的计算公式,并就某些具体的条件,对其进行了模拟验证,得到了较为满意的结果 相似文献
56.
V. P. Singh 《水文研究》1995,9(7):783-796
Error equations for the kinematic wave and diffusion wave approximations with lateral inflow neglected in the momentum equation are derived under simplified conditions for space-independent flows. These equations specify error as a function of time in the flow hydrograph. The kinematic wave, diffusion wave and dynamic wave solutions are parameterized through a dimensionless parameter γ which is dependent on the initial conditions. This parameter reflects the effect of initial flow depth, channel-bed slope, lateral inflow, infiltration and channel roughness when the initial condition is non-vanishing; it reflects the effect of bed slope, channel roughness and acceleration due to gravity when the initial condition is vanishing. The error equations are found to be the Riccati equation. The structure of the error equations in the case when the momentum equation neglects lateral inflow is different from that when the lateral inflow is included. 相似文献
57.
A realistic assessment of the total uncertainty budget of Global Positioning System (GPS) observations and its adequate mathematical treatment is a basic requirement for all analysis and interpretation of GPS-derived point positions, in particular GPS heights, and their respective changes. This implies not only the random variability but also the remaining systematic errors. At present in geodesy, the main focus is on stochastic approaches in which errors are modeled by means of random variables. Here, an alternative approach based on interval mathematics is presented. It allows us to model and to quantify the impact of remaining systematic errors in GPS carrier-phase observations on the final results using deterministic error bands. In this paper, emphasis is given to the derivation of the observation intervals based on influence parameters and to the study of the complex linear transfer of this type of uncertainty to estimated point positions yielding zonotopes. From the presented simulation studies of GPS baselines, it turns out that the uncertainty due to remaining systematic effects dominates the total uncertainty budget for baselines longer than 200 km. 相似文献
58.
Time-relative positioning makes use of observations taken at two different epochs and stations with a single global positioning
system (GPS) receiver to determine the position of the unknown station with respect to the known station. The limitation of
this method is the degradation over time of the positioning accuracy due to the temporal variation of GPS errors (ionospheric
delay, satellite clock corrections, satellite ephemerides, and tropospheric delay). The impact of these errors is significantly
reduced by adding to the one-way move from the known to the unknown station, a back move to the known station. A loop misclosure
is computed from the coordinates obtained at the known station at the beginning and at the end of the loop, and is used to
correct the coordinates of the unknown station. The field tests, presented in this paper, show that using the loop misclosure
corrections, time-relative positioning accuracy can be improved by about 60% when using single frequency data, and by about
40% with dual frequency data. For a 4-min processing interval (an 8-min loop) and a 95% probability level, errors remain under
20 cm for the horizontal components and 36 cm for the vertical component with single frequency data; and under 11 cm for the
horizontal components and 29 cm for the vertical component with dual frequency data. 相似文献
59.
Steffen Schön 《GPS Solutions》2007,11(2):107-117
GPS is a promising tool for real-time monitoring of deformations of slopes or large structures. However, remaining systematic
effects in GPS phase observations after double differencing and application of a priori models affect the resulting coordinates.
They complicate the proper separation of the actual deformations from pseudo-deformations induced by the systematic effects.
This paper shows that for small monitoring networks (baseline lengths <5 km) only affine distortions of the network geometry
are generated by the remaining distance dependent systematic effects, e.g. unmodelled tropospheric and ionospheric propagation
effects, or satellite orbit errors. Hence, a generic correction model is given by a three-dimensional affine transformation
involving a maximum of 12 transformation parameters. For the determination of these parameters, four high quality GPS stations
are necessary which are not affected by the actual deformations to be monitored. Based on the analysis of network geometries
of synthetic GPS networks with large height differences and considering the physics of the GPS observations it is shown, however,
that less than 12 parameters are sufficient for the computation of the corrections. The proposed 8 parameter model was applied
to the GPS monitoring network of the Gradenbach landslide. For this small network with large height differences, it was shown
that the distortions can be reduced by about 75%. 相似文献
60.
不确定度连续传递模型的基本步骤为:①对标准曲线的各点进行不确定度评定,给出各点的标准不确定度;②对标准曲线各点的响应值进行多次测定,得出其平均值和标准不确定度;③以这2个标准不确定度为权重进行拟合,得出双误差拟合方程和标准不确定度的计算公式;④计算标准曲线各点与其校准点的差值,并将其转换成标准不确定度;⑤将以上4项按不确定度传播规律计算总不确定度。实际测量时, ①、②、④步用插值法算得。通过一个实例比较了不同拟合方法间结果的差别,说明了运用X、Y的相对误差作为权重的直线拟和,再加上“不确定度连续传递模型”算得的测量不确定度更为合理。 相似文献