Applied Mechanics and Materials Vols. 90-93

Abstract: In view of the deficiency of algorithm for VRS (Virtual Reference Station) based on the triangular network, a novel algorithm for VRS which is based on star network is proposed. Firstly, a kind of baseline solution method of network RTK/VRS based on star structure is established and an ambiguity resolution method is also proposed in this paper. Then further research is done to analyze the algorithm of ionospheric and tropospheric correction separately. Finally, the network ambiguity resolution and correction calculation in both star structure network and traditional triangular network are verified and analyzed through two tests. These tests indicate that the Network RTK (VRS) based on star structure this paper proposed can obviously accelerate the fixed time of network ambiguity resolution, which can be up to 50%, and can achieve higher precision and reliability in the generation of network correction.

Abstract: This paper introduces a theory of selecting weight iteration applied to line type identification, image recognition, etc. We deduce the method of Selecting Weight Iteration Based on LS-TLS which having remarkable advantage when both independent variable x and dependent variable y are containing errors gross errors. And we propose its common calculation procedures, carry on accuracy evaluation. At last, this method has proved its availability by a practical example.

Abstract: In order to extract ground information more accurately, it is important to find an image segmentation method to make the segmented features match the ground objects. We proposed an image segmentation method based on mean shift and region merging. With this method, we first segmented the image by using mean shift method and small-scale parameters. According to the region merging homogeneity rule, image features were merged and large-scale image layers were generated. What’s more, Multi-level image object layers were created through scaling method. The test of segmenting remote sensing images showed that the method was effective and feasible, which laid a foundation for object-oriented information extraction.

Abstract: This paper analyzes the reason and condition of the generation of moire effect when taking photos with a digital camera, further studies a new tilt measurement method based on moire effects of SLR digital camera and then develops the general application of moirefringetechnique.

Abstract: In this paper, multinomial curved surface fitting method is used to analyze the feasibility of the GPS leveling height fitting and applicability of all kinds of models in depth. With project cases, according to the comparison and analysis based on fitting precision evaluation and the criterions of model optimization, the main applications and particular analysis methods of fitting model optimization is revealed, by which means the optimal model for the certain surveyed area is offered, conclusions of practical meaning are given, which could have positive influence on GPS practical industrialization.

Abstract: In this paper, gravity anomaly in China’s western region is computed using GOCE data and GRACE data respectively. The result shows the gravity anomaly computing by GOCE data can reflect the spatial distribution characteristics of regional tectonics and seismic activity. This new technology provides a new observed method to study seismic activity. The spatial resolution of GOCE is more higher than GRACE.

Abstract: The south line of Jinan Qingdao highway (which is short of Ji-Qing south line) spans 281km, whose geomorphy is mainly composed by mountain lands and hills. Approximately, it runs from east to west and straddles several projection zones. Systemic conformance of its layout and measurement, high precision in company with multifunctional planes and vertical control nets make up this project’s key technological problems. The report tells of the selection of central meridian in different areas of Ji-Qing south line and the layout, observation, adjustment, height fitting and precision statistics of GPS control network; the layout, observation, adjustment and precision counting of vertical control nets; Meanwhile, it analyses and discusses that how to guarantee the systemic conformance of coordinate system and vertical datum, together with eliminating the division of points’ coordinates and elevation values’ steps when primary survey design are being made synchronously in two super highways or in different areas of the same expressway.

Abstract: Due to the soft and hard threshold function exist shortcomings. This will reduce the performance in wavelet de-noising. in order to solve this problem，This article proposes Modulus square approach. the new approach avoids the discontinuity of the hard threshold function and also decreases the fixed bias between the estimated wavelet coefficients and the wavelet coefficients of the soft-threshold method．Simulation results show that SNR and MSE are better than simply using soft and hard threshold，having good de-noising effect in Deformation Monitoring.

Abstract: Based on satellite dynamics, 1 year’s CHAMP geometric precise orbit data are used in this paper to fit the satellite orbits by Cowell II numerical integral and partitioned Bayesian least square parameter estimation. Time series of low degree geopotential coefficients and are respectively calculated, which reflects obviously seasonal variations of and . The results / month, /month indicate the geodynamical shape of the earth is getting rounder and rounder and at the same time its pear-shaped component adds gradually.

Abstract: Accurately estimating the deformation of tunnel surrounding rock is a very important work for surveyors, and we adopted grey model as a forecasting means because of its fast calculation with as few as four data inputs needed, however, the original GM (1, 1) model is not fit for dynamic and long data prediction. For this purpose, we propose a novel approach to improve prediction accuracy of GM(1,1) model through optimization of the initial condition and adoption the technique of rolling modeling, the new forecasting model termed RnGM(1,1). By using the optimized model to analyze and predict the deformation of tunnel surrounding rock and comparing this optimized model with other models, we finally draw a conclusion that this optimized model is able to improve the precision of prediction and therefore can be applied to deformation data analysis.