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Application of Optimized Fractional Order EGM (1,1) Model in Deformation Monitoring and Forecasting

Information Extraction and Noise Suppression of GNSS Landslide Deformation Based on S-Transformation

Deformation Monitoring of the Baige Landslide in the Jinsha River Using PS-InSAR and Offset Tracking Techniques

On October 11, 2018, a landslide occurred near Baige village, Polo town, Jomda county, Tibet. As a result, flow cut-off occurred in the Jinsha River and a barrier lake formed. Based on the GF-2 and GF-3 imagery, we analyze the influence of the barrier lake on villages and towns upstream. Based on Sentinel-1 and ALOS-2 PALSAR-2 images, we apply separately PS-InSAR and offset tracking techniques to obtain the motion characteristics of the landslide before the occurrence of the disaster. The results show that the Baige landslide has obvious slip before the disaster. According to PS-InSAR results, from 2017 to 2018, the average rate of some PSs in the LOS direction at the edge of the Baige landslide exceeds 2.5 cm/a, and two suspected landslides are found around the Baige landslide; According to offset tracking results, Baige landslide shows the feature of accelerating sliding in the three time periods from July, 2015 to July, 2018; the cumulative sliding distance exceeds 30 m. The application of InSAR can identify active landslides before landslide disaster occurs, providing an important basis for landslide monitoring and warning.

To get the crustal vertical movement rate result, we use linear deformation models based on 13-period first-order leveling observation data from 2006 to 2018 in the Guanzhong region. On the basis of the crust vertical rate results, we make qualitative and quantitative analysis of the research area. It is shown that the vertical rate of Weihe basin, except the Xi’an area, is about -1 mm/a, the vertical rate of southern Ordos block is 3-5 mm/a, the vertical rate of northern piedmont of Qinling is 3 mm/a, and the vertical rate in Qinling is less than 1 mm/a. The dip rate and the locked depth of the main faults in the research area are inversed, based on the vertical movement rate by means of rectangular dislocation model. The inversion results show that the dip rate of Kouzhen-Guanshan fault is 655 mm/a with 4.6 km locked depth, the dip rate of Weihe fault is 3.21 mm/a with 3.4 km locked depth, and the dip rate of north margin of Qinling fault is 5.34 mm/a with 9.8 km locked depth. Finally, we provide reasonable interpretation and analysis about the vertical movement result. Combining with previous research results of this research zone, the relation between the present crustal deformation and dynamic mechanism will be explored for providing certain basic data in regional seismic risk and geodynamic research.

This research aims at the contemporary crustal deformation of northeast Tibet using the GPS three-dimensional strain analysis method, based on the Green function of elastic thin sheet. This study shows that the characteristic of crustal deformation in northeast Tibet is predominated by the NE-SW convergence along the strike-slip fault, while in the blocks between the faults the strain is relatively low. Meanwhile, the vertical strain is very high in the east of Riyueshan fault and south of Haiyuan fault, which may be related to the block rotation and eastward extrusion partitioned by the crustal shortening, as well as the middle-lower crustal flow. Our research provides a new perspective for understanding the dynamic process of tectonic deformation in the continental interior.

Interseismic Deformation Monitoring of Xianshuihe Fault Zone Based on Sentinel-1 Data

In this study, we obtain the interseismic deformation velocity field of Xianshuihe fault from 2015 to 2018 based on Sentinel-1 satellite data by using InSAR technology. Our research shows that the InSAR results are reliable and in good agreement with the GPS monitoring results. The deformation velocity field shows that the Xianshuihe fault has obvious sinistral strike-slip movement characteristics, with a slip rate of about 7-11 mm/a, and shows a decreasing trend from northern to southern segments. What’s more, in the vicinity of the M6.3 Kangding earthquake in 2014-11, the slip rate there reaches 15 mm/a due to the post-earthquake influence.

In this paper, we select eight blasting event waveforms with higher SNR in blasting events as template events using seismic event data from the Inner Mongolia Seismic Network. The recognition algorithm is a template matching method based on waveform correlation coefficient. The results show that when the magnitudes are similar, the correlation coefficients of the corresponding waveform of the same type of earthquake events are relatively large, which can be used as a basis for identifying the types of earthquakes.

Based on the compressed sensing sparse signal sampling and reconstruction theory, the AVO inversion method is used to change the traditional L2 norm to the L1 norm, and the sparse pulse reflection coefficients of the underground stratum under the L1 norm are retrieved. The sparse spikes obtained from the inversion represent the local underground structure by the superposition of a limited number of layered structures, which can improve the longitudinal accuracy. Compared with the traditional AVO inversion algorithm, it improves the inversion effect of thin layers and has a certain anti-noise. The numerical model and actual data results show that the L1 norm AVO inversion method based on the compressed sensing principle is more accurate and has higher resolution.

Precise Real-Time Orbit Determination Model Using Space-Borne Single-Frequency GPS Observations

To eliminate the influence of the ionosphere we construct the group and phase ionosphere correction (GRAPHIC) with single-frequency GPS pseudo-range and phase observations. At the same time, we add pseudo-ambiguity parameter to the orbit determination filter to absorb the broadcast ephemeris errors. We assess the absorption effect and accuracy of real-time orbit determination for space-borne single-frequency GPS with real GPS measurements of 8 different low earth orbit satellites. The results show that the accuracy of real-time orbit determination improves greatly with GRAPHIC measurements. The position accuracy is 0.44-055 m and the velocity is 0.37-0.63 mm/s. The accuracy improvement is about 40% compared to the traditional dual-frequency pseudo-range real-time orbit determination method. We believe that with the real-time orbit determination algorithm mentioned in this paper, high precise orbit determination results can be achieved with low-cost single-frequency GPS receiver.

We analyze and improve the layout of the PCM model. First, we introduced the PCM and the locking depth multiple models. Then, when the minimum effective distance (MED) is equal to 6.31-fold, we compare the results of the two layout modes by the accuracy evaluation method. The results are not much different. We study the optimal selection of the minimum effective distance (MED), then evaluate the advantages and disadvantages of the PCM model and the locking depth multiple layout model. The results show that the 20-fold locking depth of MED is more reasonable than the 6.31-fold locking depth. In the case of 20-fold locking depth in MED area, the PCM model layout mode is better than the locking depth multiple model. The PCM model layout model is applied to the Qiaojia-Dongchuan section of the Sichuan-Yunnan region for inspection. The results show that the results of the PCM model are more accurate than those obtained from the current sites distribution. The research is of great significance for accurately obtaining deformation parameters in fault deformation monitoring.

Preliminary Assessment and Comparison of Positioning Performance between Typical Low-Cost Navigational and Geodetic BDS Terminals

In this work, we compare the BDS positioning performance of a typical low-cost navigational-type terminal with a typical high-performance geodetic terminal, based on the zero-baseline data. The comparisons are carried out by pseudorange-based single point positioning, pseudorange-based single-frequency relative positioning, and carrier phase-based single-epoch single-frequency relative positioning. The results show that the positioning accuracies of the pseudorange-based single point positioning and relative positioning for the Beidou low-cost navigational terminal are slightly lower than that of the geodetic terminal, and the difference of the carrier phase-based relative positioning performances between the geodetic and navigational terminals are very significant since the centimeter-level positioning result cannot be achieved by the navigational terminal.

Based on the data analysis of 4 radiosonde stations in Guangxi and GGOS Atmosphere grid Tm, we establish the temperature decline rate model with the increase of altitude. According to the temperature decline rate model, the inverse distance weighted, bilinear interpolation, new inverse distance weighted and new bilinear interpolation are used to calculate the Tm of the sounding stations. Based on the analysis of interpolation error, we establish the Tm model of non-meteorological parameters in Guangxi and compare it with Bevis model, eastern China model, and Guangxi model. The results show that the interpolation accuracy of the temperature decline rate model is obviously higher than those of the other 3 models. The average absolute error (MAE) and root mean square error (RMSE) of the 4 methods are between 1 and 2 K. We further improve the interpolation accuracy of Tm model of non-meteorological parameters in Guangxi. The MAE of Baise station is about 2 K, and the MAE and RMSE of other stations are about 1 K, which can meet the accuracy requirements of precipitation water vapor inversion.

Accuracy and Applicability of Different Tropospheric Zenith Delay Models in Shaanxi Province

In this paper, we use MATLAB to realize five models of UNB3m, GPT2w+Hopfield, GPT2w+Saastamoinen, GPT3+Hopfield, GPT3+Saastamoinen. We analyze their applicability in Shaanxi. The results show that the model calculation results are generally small in Shaanxi province. The overall accuracy of the GPT2w+Saastamoinen and GPT3+Saastamoinen models is comparable and superior to the other three models, with bias of 1.41 cm and RMS of 4.68 cm and 4.67 cm respectively; the precision improves as elevation increases. The accuracy of the five models varies with the seasons; UNB3m has the most significant change. The bias difference in summer and winter is 7.92 cm, and the RMS difference is 7.67 cm. For higher precision calculation, GPT3 should be used in autumn, while GPT2w works better in spring and summer. When using the same meteorological parameter model, the Saastamoinen model is more suitable for Shaanxi than the Hopfield model, and northern Shaanxi has the best longitude. In the comparison between two latest models GPT3 and GPT2w, we find that the four meteorological parameters calculated by the two models are slightly different, including surface air pressure, surface temperature, surface water pressure and weighted average air temperature. The difference between the total tropospheric delay ZTD and the tropospheric dry delay ZHD calculated by GPT3 or GPT3 is small, and the PWV calculated by the tropospheric wet delay ZWD is almost the same.

Prediction Models of Ionospheric TEC by MEEMD and Elman Recurrent Neural Network

In this paper, we combine modified ensemble empirical model decomposition (MEEMD) algorithm with Elman recurrent neural network (ERNN) to predict TEC by values of different latitudes provided by IGS center. At different latitudes which are under low, medium and high, the experimental results show that the smallest mean square errors of 5 days’ ionosphere TEC is 0.96 TECu and the best relative precision is 95.4%. Our model is better than the EMD-ERNN model and the single ERNN neural network model

Comparative Study of Point Cloud Data Interpolation Based on Ground-Based LiDAR

Taking typical geomorphologic point cloud data on Lenglongling fault as an example, this paper uses five interpolation methods such as nearest neighbor, inverse distance weighting, triangulated irregular network, spline and Kriging, to fill the missing point cloud interpolation. The most suitable interpolation algorithm is discussed. Experiments show that the triangulated irregular network interpolation method not only fills the missing data of point clouds, but also accurately represents the elevation data according to actual topographic changes. This restores the real scene in the field, providing technical guidance and data guarantee for future research.

A Linear Feature Point Cloud Registration Algorithm Based on the Relation between Point and Plane

Aiming at the problem that the traditional point cloud registration algorithm cannot solve the registration problem of missing points with the same point, in this paper we derive a point cloud registration model using the linear features with strong geometric constraints. Our model is based on the geometric relationship of points on a plane, which is represented by unit quaternion and does not need to exactly correspond to the endpoint of a line with the same name. The experimental results show that this model can not only solve the registration parameters synchronously, but also can be applied to the registration problem of large rotation angles, which reduces the requirements of the registration model on the initial value of parameters and enhances the stability and practicability of the registration model.

Truncated Regularized Solution to Ill-Posed Model and ItsUnbiased Estimation of Unit Weighted Variance

The regularized method improves the ill-posedness of the normal matrix by introducing the regularized parameter to correct the singular values. However, it is obviously unreasonable to correct the singular values without distinction. In this paper, we compare the trajectory decomposition expansions of the regularized mean square error and the least squares solution variance, analyze the relationship between the change of the mean square error of the solution caused by the modified singular value and the singular value, and determine the conditions for singular value correction. Based on the residual quadratic expectation formula, an error calculation formula for unbiased unit weights with improved regularization is derived. Finally, numerical examples and ill-trimmed network examples are used to verify the correctness of the formula.

A New Algorithm for Solving Inequality Constrained Rank Deficient Adjustment Problem

We propose a new algorithm for solving the inequality constrained rank deficit adjustment problem. The algorithm expresses the prior information as an inequality form and forms an inequality constrained rank deficit adjustment model with the rank deficit adjustment model. Combined with the Karush-Kuhn-Tucke condition, the model can be transformed into a linear complementarity problem and then solved by the Lemke algorithm. The method overcomes the insufficiency of the necessary starting data in the rank-deficit network, and the calculation is stable and the efficiency is higher. Finally, we simulate the GPS network with rank loss of prior information, and combine several classical rank-loss adjustment methods to verify the effectiveness of Lemke algorithm in dealing with inequality constrained rank-deficient problems.

A New Method to Estimate Gross Errors——Prior-Variance Undecided Parameter Method

In this paper, we introduce a new method, prior-variance undecided parameter method (PVUP), to estimate gross errors using prior variance without Least-Square or hypothesis testing. Starting with fundamental principles, we give the model of this method next. Last, we demonstrate its simplicity and validity using some examples compared with other methods, such as QUAD.

Deformation of the Solid Earth Tides for SNERI Earth Model Based on Spectral-Finite Element Method

This study presents the application of the spectral-finite element method on the solid tide response calculation of SNERI Earth. The weak formulations of Earth tide deformation equations are given respectively, by means of the Hamilton’s principle in the solid Earth and the approximation of neutral stratified fluid in the liquid core. The solution space is divided into a certain number of concentric spherical layers. Hence spherical harmonic functions are used to span the 2-D spherical shell and linear functions are used to interpolate in the radius direction. Compared with the analytical solution of a homogeneous earth, the numerical solution shows that the numerical precision of spectral-finite element method can up to 10-8 magnitude in 1 km equal radial divided interval. As respect to the PREM Earth model, the numerical solution difference of 2nd and 3rd degree tide Love numbers between spectral-finite element method and Runge-Kutta mothed is at about 10-4 magnitude; the average difference of tidal gravimetric factor between the 8 main tidal waves observational results, recorded by superconducting gravity meter in Wuhan station, and theory results, calculated from spectral-finite method, is about 0.15%. The results show spectral-finite method has good convergence and high numerical precision and is more powerful in high precision numerical calculation of complex Earth tidal Love numbers.

Volumetric strain observation data is influenced by pumping more rural living and spring farmland irrigation water. In this paper, three cases of influence by water pumping are analyzed. It is hoped that the study can provide some help in eliminating the interference factors of volumetric strain and to obtain accurate data.

Data Decoding Method of the Displacement Sensor and ItsApplication in Landslide Monitoring