In this paper, the anomalies of fault deformation before the Aug. 8th, 2017 Jiuzhaigou MS7.0 earthquake, and their variations after the quake, are analyzed. We use the data of across-fault short-leveling at the northeastern margin of Qinghai-Xizang block, together with added data observed in August and September after the quake, with the aid of observational curves and time-space evolution of the anomalies, as well as the index of feature intensity. The results show that: Over one year before the earthquake, the anomalies are relatively concentrated at the area from western Qinling to Liupanshan tectonic region; 1-3 months before the earthquake, short-term anomalies at the western Qinling tectonic region and nearby display an increasing trend within the distance of 300 km of the epicenter; this mainly reveals abrupt thrust change characteristics, which have medium-short-term and short-term precursory features; one month after this earthquake, most anomalies had adjusted and recovered.

Based on the investigation of observation system, observation environment and auxiliary material, we think that the leveling deformation anomaly of Taiyuan station is credible, but it is affected by the change of water level. Through the investigation on exploitation of the pumping wells with the same layer, the reverse rising of leveling in Taiyuan station is associated with the recovery of water level because of small coalmines that have been shut down since 2009.

On 9th August, 2017, an MS6.6 earthquake occurred in Jinghe county of Xinjiang, China. In this study, ascending and descending tracks of Sentinel-1A/B images are employed to derive the precise coseismic surface displacements, then a two-step inversion strategy with uniform slip model and distributed slip model is used to estimate the fault geometry and coseismic slip distribution. InSAR results show that the coseismic deformation range is about 30 km×40 km. Our model suggests that the distributed slip mode can fit the observations very well. The earthquake fault is a thrust fault with a strike of 83.8°, a dip of 40.6°, a rake of 89.1°, a focal depth of 20.7 km, and the moment magnitude is 6.3, which is consistent with seismological results. The causative fault of Jinghe earthquake is Kusongmuxieke mountain front fault, and this earthquake is caused by the dislocation at the deep of thrust fault zone in the northern Tianshan mountains, Xinjiang.

he Pangusi-Xixiang fault tendency reversed near the Dagao village. The western part is south tendency and east part is north tendency. In order to determine the inversion genesis in the Pangusi-Xinxiang fault tendency reverse regional, we set 3 shallow seismic survey lines across the fault. Based on the high-resolution seismic data acquisition and high-precision data processing technology, the clear underground structure and tectonic imaging is obtained of the fault tendency reverse regional. The results show that there is a hidden uplift in the north edge of the Wuzhi uplift, and the development of the hidden uplift makes the western part of the Pangusi-Xinxiang fault disappeared between L1 and L2. At the same time, the Wuzhi fault became the boundary fault of the Jiyuan sag. From west to east, the hidden uplift scale increases gradually. The east part of the Pangusi-Xinxiang fault and the Pingling fault began to develop at the margin of the hidden uplift. With the hidden uplift increasing, the activity of Pangusi-Xinxiang fault and the Pingling fault gradually increases. It is suggested that the hidden uplift is the main cause of the tendency inverse of the Pangusi-Xinxiang fault. The results provide a reliable basis for the characteristics and activity evaluation of Pangusi-Xinxiang fault.

This study conducts image processing of 33 ENVISAT ASAR data covering the northern area of Langfang city and extracts the annual average velocity and quarterly series information of land subsidence in the time span of 2007-2010. In addition, coupled analysis of subsidence monitoring data and influencing factors information is carried out to analyze causes. The results show: that the higher scale settlement areas are mainly distributed in Songzhuang-Yanjiao, Wubaihu-Dakoutun and other scattered areas with seasonal fluctuation due to rainfall recharge; there appear differential subsidence characteristics exhibiting high subsidence gradients in the mountain frontier and Yanggezhuang-Mafang areas, while monotonous appearances between rather high land subsidence gradient distributions and the -16 mm/a and 0 mm/a contour lines; there are rather high or gradual subsidence gradients on both sides of the faults in the northern and eastern parts of study area, due to the fault activities and significant difference in the thickness and structure of Quaternary aquifers system; an high agreement with the distributions of water head sites and drawdown area, revealing that the overexploitation of deep confined water and urbanization construction are the primary cause of severe subsidence.

A new multi-scale deformation prediction method is proposed based on improved local mean decomposition (LMD) and weighted kernel function relevance vector machine algorithm (RVM). The deformation data is decomposed into several physical deformation components by LMD, and each deformation component is predicted by RVM optimized by genetic algorithm. Finally, a multi-scale deformation prediction method is established and applied to dam deformation prediction by adding the prediction results of each deformation component. The experimental results show that the improved LMD-RVM method is superior to the BP neural network method, RVM method and the improved EMD-RVM method in many precision indexes, which proves the effectiveness and reliability of the new method.

In this paper, based on the STK software, the simulation of the BDS satellite constellation structure in September 2016 is carried out. The average visible satellite number, DOP value and system availability are taken as indexes to evaluate the constellation design structure. After the failure of single satellite and all tilted satellite (IGSO) and geostationary satellite (GEO), the impact of satellite failure on the availability of BDS in mainland China is analyzed. The results show that the latency of the BDS region is weakened by IGSO4 and GEO5 when the threshold is 2.60. Taking the BDS satellite during normal operation of the GDOP region average maximum value (S=2.60) as the system availability threshold, the system availability is decreased by 1.79% and 32.63%. When the threshold is 2S(5.20), 3S(7.80), 4S(10.4), 5S(13.0), the availability of the system can reach 100%. After the failure of GEO as a whole, BDS high-precision positioning can still be partially available, but the availability of BDS system is greatly limited after the failure of IGSO. Therefore, to increase the on-orbit backup of the satellite, we need to focus on the GEO5, IGSO4 satellite backup, and the appropriate increase in the number of IGSO satellites.

A method to improve BDS positioning using GPS antenna phase center correction is introduced, as there is no authority agency provide the information of BDS receiver antenna phase center so far, limiting high precision positioning. They are deduced and argued from two aspects: precise point positioning (PPP) and relative positioning. By using these processing methods, the up component of BDS PPP is improved from 1dm level to several cm, and the up component of relative positioning is improved from cm level to several mm. The results indicate it is reasonable to use these methods.

In this paper, the ill-conditioning diagnosis and processing of Kalman filter are combined. First, the ill-conditioning of Kalman filter and the disadvantage of ridge-type Kalman filter are analyzed. Then, the signal-to-noise ratio (SNR) statistic is introduced to measure how much each parameter suffers from the ill-conditioning. Accordingly, all parameters are divided into two parts: involved parameters and non-involved parameters. Then, the two parts of parameters are corrected with two ridge parameters of different sizes. This method is named double-parameter ridge-type Kalman filter and can reduce the bias introduced in ridge-type Kalman filter, while reducing the variance of the state parameter estimation. Finally, in the simulation, the new algorithm is discussed in detail with a specific mixed navigation constellation of 5 GEO, 3 IGSO 24 MEO. The results show that the new algorithm has higher orbit accuracy relative to ridge-type Kalman filter and the common Kalman filter.

In this paper, the Helmert variance component estimation based on Kalman filter is introduced to adjust the weights of observations in combined GPS/BDS precise point positioning. Meanwhile, the Kalman filter prediction value is taken as a quasi observation; it can be treated using variance component estimation with observations for the difference in unit variance between prediction value weight ratio and observations weight ratio. The experimental results show that this method can reasonably determine various observations weight ratio of the current epoch. Moreover, it can effectively adjust the value of the observation and the value of Kalman filter. Thus, the positioning accuracy and reliability of GPS/BDS combined PPP are obviously improved.

In this paper, the effects of SSR corrections of different update frequency on RT-PPP and the interrupt of SSR corrections will be discussed. The effects of this problem on practical applications are analyzed. According to the experiment, if the update frequency of corrections on the service terminal could be controlled within 30 s, it will obtain the accuracy of centimeter-level positioning. If the interrupt of corrections on the client can be controlled within 150 s, it will also obtain the accuracy of centimeter-level positioning, and 200 s will obtain the accuracy of 20 cm and 300 s will obtain the accuracy of decimeter-level.

Radio occultation technology is an effective means of neutral atmospheric observation. This paper briefly introduces the basic flow of GPS-LEO neutral atmospheric radio occultation inversion. Considering the influence of various error sources on the inversion of atmospheric parameters, we use EGOPS simulation software to simulate 426 occultation events a day using 3D ray tracing method, analyzing the influence characteristics of many error sources. The statistical analysis of the inversion temperature shows that the stability of the satellite clock and the accuracy of the satellite orbit determination can meet the occultation inversion demand. The noise error has a great influence on the inversion, and effective measures are needed. For the multipath effect, the influence of the periodic error is small, but the amplitude has some influence on the inversion result, and it needs to be effectively suppressed.

This paper analyzes the accuracy of Galileo spatial signal and Galileo broadcast ephemeris at the present stage. We examine statistics and analyze 30 days health satellite ephemeris in this paper. The results show that the satellite orbit error of FOC and IOV is better than 0.8 m, and the radial error is the smallest. The accuracy of the Galileo satellite clock bias is 1.0 ns. From the spatial signal ranging error to the Galileo satellite, the accuracy of the broadcast ephemeris is better than 1 m, and the accuracy of FOC is equivalent to that of IOV satellite. Single point positioning using broadcast ephemeris precision can reach up to the decimeter level.

The mesoscale eddies in the South China Sea are extracted and analyzed by geometric velocity method based on sea surface temperature data and sea level anomaly data. The results show that both sea surface temperature and sea level anomaly data can extract eddies; the two extraction capacities are basically the same but there are differences: sea surface temperature data can extract small scale eddies but show instability when tracking eddies, while sea level anomaly data cannot detect small scale eddies but shows stability when tracking eddies. In addition, the temporal and spatial distribution of these eddies extracted by the two data are consistent.

The traditional radiometric distortion correction methods for side scan sonar (SSS) image make it difficult to resolve the problem of fine image acquisition in complex sea bottom sediment and operating environment. Based on radiometric distortion of SSS image, a comprehensive radiometric distortion correction method is proposed. This method has been applied in Jiaozhou bay, eliminating the influence of marine environment, obvious variation of sea-bottom sediment and adjustment of time vary gain (TVG) parameters, realized the high-quality acquisition of images under complex marine environment and noise. Compared with the traditional statistical method, the entropy value of the image is reduced and the peak signal to noise ratio (PSNR) is increased, which indicates that the SSS image quality has been improved effectively.

Traditional waveform fitting algorithms are not robust to noise. Moreover, these algorithms cannot detect water column scatter or weak signal and complex waveform shapes accurately. To overcome these problems, a method based on generalized Gaussian model is proposed. First, the algorithm estimates noise by calculating the difference between the last part of the original waveform and the filtered waveform. Then, it uses the generalized Gauss model to extract surface and bottom reflection signals, and to simulate the residual signal by iterating. At last, the parameters are optimized using the LM algorithm. In order to avoid redundant components, this paper gives some constraints. This algorithm is tested by measured data from the South China Sea, and it can detect weak signals and complex shapes. Whether in shallow or deep water, the fitting precision of this algorithm is better than traditional algorithms and it presents robustness.

Terrain features play an important role in cartography, earthquake geology, terrain classification and DEM production. In order to obtain terrain features more effectively, a rapid terrain features extraction algorithm of airborne LiDAR is proposed in this paper. Firstly, constructing the quadric surface fitting model, the geometric rules of airborne LiDAR data and fitting model are established. Then, the LM(levenberg-marquardt) algorithm is adopted to optimize the parameters of the topography and obtain the optimal results. In addition, the fitting time and fitting precision are calculated. Finally, the terrain features are extracted rapidly based on the terrain fitting model. To verify the algorithm’s efficiency and accuracy, the airborne LiDAR experiment indicates that when the optimal search radius is 2 m, the fitting time is only 0.02 s and RMSE is only 5.09 cm.

Aiming at the problem of circular curve fitting, based on the parametric equation of circular curve, firstly this paper establishes the EIV model of circular curve fitting, and transforms the model into a more reasonable Partial EIV model for the characteristics of the coefficient matrix. Then, the formula is transformed into the least squares form, and the two-step iterative method is used to solve parameters of the model, ensuring that the corrections of the same elements in the coefficient matrix are same, and the corrections of the constant elements equals zero. Finally, combing case data shows the feasibility of this algorithm, and fitting accuracy is relatively superior.

The determination of regularization parameters is the key to the inversion of coseismic earthquake slip distribution. In view of the selection of regularization parameters in seismic slip distribution inversion, the U curve method is proposed in this paper. Using the U curve method and L curve method to design the simulation experiment. Moreover, the two methods are applied to the inversion of Lushan earthquake. The inversion results of simulation experiment and the Lushan earthquake show that the regularization parameters obtained by U curve method has the advantage of high accuracy and no need to rely on data fitting accuracy than L curve method in coseismic slip distribution inversion.

Based on the continuous stress observation data of four component deep borehole in Tangshan from 2016 February to November, we calculate the time-frequency characteristics of tectonic information in the Tangshan area using the S-transform technique. We analyze the consistency between the earthquakes with magnitude larger than 3.5 and the continuous observation data of crustal stress. The results show that there is a high frequency energy cluster existing from the 1 440 min to 720 min cycle range before the earthquake, showing great diversity with the tide factor. We used observations before and after the April 15, 2016 M7.0, Kyushu, Japan, earthquake to study the coseismic effects of large earthquakes in the far field. The results show that the far-field seismic events mainly affect the frequency bands less than 240 min, which means the high frequency energy cluster may come from the dynamic adjustment of regional tectonic stress field. In our opinion, there is a high precursory correlation between the time frequency evolution characteristics of tectonic stress and the earthquake events.

Zero drift stability is an important performance parameter of the CG-5 gravimeter, determining the accuracy of the instrument to a great extent. The zero drift stability can be divided into static zero drift stability and dynamic zero drift stability. Based on the zero drift stability analysis of four CG-5 gravimeters purchased at different times, we evaluate the static zero drift stability of CG-5 gravimeter using the correlation coefficient of the fitted linear, and evaluate the dynamic zero drift stability of CG-5 gravimeter using average dynamic zero drift rate. The experimental results show that the method can effectively evaluate the zero drift stability of the CG-5 gravity meter.