Existing problems in the process of identifying gravity anomalies include cumbersomeness and complication of calculation, along with lack of uniformity in parameters and coordinate system.We develop a cross platform, cloud computing software system (OnGra) of the gravity anomaly field in order to resolve these issues. In accordance with the norms of the regional gravity survey and large scale scale gravity exploration specification, we design, reconstruct and integrate the existing gravity anomaly field processing algorithm with an adaptive extraction algorithm of regional digital terrain model. The software system can batch and automaticallycalculatethe air anomaly, the Bouguer gravity anomaly and the isostatic gravity anomaly from the field observation of gravity/GNSS. It can also calculate these anomalies based on satellite gravity field models in the specific region.

In this paper, using GPS observations of crustal movement observation network of China(CMONOC) from 1999 to 2015, we obtain the horizontal velocity field of the western Yunnan rhombic block, which is located in southeast of the Qinghai-Tibet plateau. It turns out that direction of the present-day crustal movement of this area, relative to the Eurasia plate, generally shows a clockwise rotation from east to southeast and from southeast to southwest. The magnitude of velocity in this research area shows that the value of velocity in the middle of rhombic block is greater than that on the sides, and the value shows a reducing tendency from north to south. The maximum shear strain rate of this area, calculated by triangle method, shows that higher valuesare concentrated in the east and west border of rhombic block. The direction of principal strain shows the state of east-west compression and north-south stretch. The fault zone on the east side of western Yunnan rhombic block presents sinistral movement and the fault zone on the west side presents right-lateral movement, which is identical to the results from geological survey.

Based on 2009-2015 GPS velocity field data, the crustal strain field of Yunnan province is calculated and strain accumulation characteristics of two GPS stations selected at Honghe and Qujiang faults are analyzed. The results show that: (1) The Honghe, Qujiang, Xiaojiang main fracture strain fields contain tension and compression about time and space evolution characteristics. Recently, the south section of the Qujiang fault presents tension east-west. The northern section of the Honghe fault extension is larger, about 12.0×10-8/a, and the main performance of the southern Yunnan is pressure changes in NNE. (2) From the GPS profile, the Honghe, Qujiang faults show dextral strike slip and extensional variation in the two directions. However, from the value, the movement rate is larger in the north of the Honghe fault, where the strike slip rate is about 8.90 mm/a.

Using GPS, borehole strain and digital seismic data, we study the horizontal deformation and tectonic stress fields in the Chongqing area. The results show that the inside of the Chongqing region presents relative motion of 0~3 mm/a and presents certain features of the dextral. The region as a whole performs as pressure characteristic. The predominant principal compressive strain direction of the local region is in a NWW direction, the direction of the tectonic stress field direction is consistent, the direction of the part of the region near the impact fracture appears to be a NNE direction, and the maximum shear strain contour line is southwest of Chongqing. Northeast and southeast Chongqing show a high gradient zone, and the gradient belt corresponds to the Chongqing area of the main area of seismic activity.

According to the force mechanism, the control fissures of shear-type unstable rocks are classified into compression-shear and tension-shear types. A calculating method of cracking angle (θ0) and fracture toughness (GIC) are put forward using a maximum strain energy release criterion. Taking Shoulishan typical unstable rocks in Wanzhou district of Chongqing, China, as examples, the calculation results show that the cracking angles with maximum strain energy release criterion are the same as those with maximum circumferential stress criterion. The cracking direction of the control fissures points to the free face.

Geodesy data usually contains many uncertainties with unknown statistical information, possibly causing morbid theory model and affecting the accuracy and reliability of parameter estimation. This paper researches the mechanical principle of the nonlinear time series evolution system of slope displacements, and improves the original model by using polynomial fitting. In the process of parameters calculation, the negative influences of results caused by uncertainties of measurement data are considered. The accuracy ofparameters calculation is improved by restricting uncertainty and using the min-max criterion. Comparing the forecasting results with displacement observational data shows that the results of the least-squares with uncertainty (ULS) approach are closer to measurement data, as compared with least-square (LS) and total least-square(TLS). It is also indicated that the effectiveness of predicting displacements by improved nonlinear time series evolution system of slope displacements.

Least squares estimation and partial errors-in variables total least squares donot have the ability to resist gross errors. As gross error may also appear in the observed value and the coefficient matrix in differential equations, this paper puts forward a partial errors-invariables total least squares model based on IGGⅢ differential resistance. This paper also compares the robust least squares,partial errors-in variables total least squares with the new algorithm systematically,usingparameter estimation results, stability through simulation data, and high-speed railway observations data. The results show that the new algorithm's accuracy is high, which can be applied to the high-speed railway subsidence prediction.

This paper uses the fixed stations of wideband digital seismic waveform data, and calculates the focal shock parameters of the MS4.3 earthquake sequence in Badang county in June 16, 2017. We determine focal shock parameters,including apparent stress, corner frequency and source radius,of 16 earthquakes greater than ML1.8. The relationship between the stress and the parameters is analyzed systematically. Results show that the apparent stress value and the magnitude of earthquakes are positively correlated, the seismic source spectrum of high frequency components is not rich, corner frequency and apparent stress values are far less than the tectonic earthquake, and the underground structure is more complicated in the earthquake source area.

Based on comparative analysis of petroleum seismic and high-resolution shallow seismic profiles, combined with the focal mechanism solution and earthquake location results, we establish the shallow-deep faults distribution below the Taikang MS4.7 earthquake zone. Combining regional tectonic evolution from the late Cretaceous to Paleogene, NWW and NE-NNE shear strike slip movement in Taikang uplift makes the uplift break up into alternately tectonic conditions.Since the Neogene,under the background of the whole deposition of the Taikang uplift, tectonic activity has weakened, but tectonic deformation style alternately continues, showing sustained activity of rift boundary fault control.Furthermore, the formation of a series of Neogene Quaternary normal faults indicates the existence of deep strike slip extension.The deep source structure of the Taikang earthquake area is near NW and NE high angle faults, and the shallow structural performance is alternately tectonic style controlled by near NW strike slip faults. The deep and shallow structures controls the occurrence of the Taikang MS4.7 earthquake and its aftershocks.

We investigate the regional characteristics of the slope of the initial part of the P-wave envelope, which is used to determine epicentral distances in the Japan Meteorological Agency and Japan Railway Company earthquake early warning (EEW) systems. The Tohoku region is chosen as the study region. 265 events are collected. By fitting the function Bt·exp(－At) to the initial part of P-wave envelopes, we obtain sets of the parameters of A and B. Then, the intercepts of the above formula for each event are determined, keeping the slope to -2.27 to investigate the regional characteristics. Two tendencies emerge: shallow events have lower values of c, and deeper events have higher values of c.

This paper selects 14 moderate earthquake (6.5<MW<7.5) events near mainland of China occurred during 2004 to 2015. Analyzing records from Enshi, Kunming and Xi’an stations which are equipped with STS-1 broadband seismographs and records from Lijiang and Wuhan stations which are equipped with superconducting gravimeters, we can obtain observed spheroidal modes. According to the focal mechanism solution of seismic events and lateral homogeneous earth model, we calculate the synthetic values of spherical modes of each station. Then we compare discrepancy in the amplitudes and frequencies between observations and synthetic values to analyze lateral features of underground structure of areas covered by Chinese mainland stations. Results show that the observed amplitudes agree well with synthetic modes at 3.0~6.0 mHz, it’s a clear evidence that there is not large scale lateral inhomogeneous structure in the upper mantle below 200~660 km especially in those areas around selected stations in Chinese central mainland.

In this article, we study the ground motion peak acceleration and spectrum characteristics through the loess valley earthquake site.Results show that under the effect of topography and soil, common PGA magnification is roughly equal to separate under the action of PGA amplification factor of the product. At the same time, analyzing the Fourier spectrum and spectrum of peaks and valleys, we find that topography amplification effects under the action of the topography and soil is equal to the product of their individual topography amplification effects.

Static precise point positioning can reach the centimeter level, but the positioning is an average of many epochs’ coordinates in any ITRF. The point coordinates in any ITRF and epoch can be obtained by the conversion of frame and epoch. In this paper, 93 d of data from the continuously operating reference station are processed by online GNSS data processing software, including APPS, CSRS, GAPS, magicGNSS and AUSPOS. Then, the positioning is converted into the CGCS2000 coordinate system by the conversion of frame and epoch. The results show that the average precision of the PPP results of 24 h is 1.7 cm. When we transform the PPP results of 24 h into CGCS2000 coordinate system with the velocity field in ITRF2008 provided by crustal movement observation network of China and the natural neighbor interpolation method, the transformed precision is 1.6 cm.

Compared to the single satellite system, the multi-GNSS could improve the visible satellites’ geometry distribution outstandingly, and further enhance the reliability of ambiguity resolution. This article analysis the products and methods used in PPP ambiguity resolution (PPP-AR) which provided by analytic centers. Then corresponding experiments are conducted to verify the performance of multi-GNSS PPP-AR. It turns out that satellites orbit products provided by analytic centers are highly consistent, and these could provide a better precision datum for PPP. This could accelerate the process of PPP-AR, and also enhance the positioning accuracy when the initial fixed of PPP-AR.

The convergence speed and the precision of integrated multi satellite systems have a great relationship with the number and the space configuration of visible satellites and efficiency of system algorithm. The traditional selection algorithm cannot rapidly obtain the ideal spatial configuration, so, in this paper, the influence factors of the positioning accuracy calculation model and the GDOP value of integrated multi systems are discussed. An algorithm of convex hull with Graham’s scan is analyzed and then a fast satellite selection algorithm based on convex hull with Graham’s scan for multi satellite systems is achieved by programming. Meanwhile, simulation experiments are carried out on the selection effect and positioning efficiency of the proposed algorithm. Experimental results show that the number of selected satellites in this algorithm can be stabilized at 8 to 10, the constellation GDOP is obviously optimized and the spatial configuration is obviously improved.The optimization rate of convergence time reaches 40%, 20% and 7% corresponding respectively to X, Y, H with the traditional algorithm, and the positioning accuracy is higher. These results hold important significance in quick repair of ambiguity and improving positioning efficiency.

BDS is composed of three different heights of orbital satellites and broadcasts three-frequency signals, which may lead multipath to present new features. These characteristics cause the multipath error of BDS observations to possibly differ between constellation and the frequency.Based on this, by using the 17 GNSS multimode observatory data from the MGEX and iGMAS,the diversity of BDS multipath error is analyzed from five aspects of elevation angle, signal frequency, receiver type, tracking station distribution and satellite constellation. At the same time, the multipath errors of GPS observations are compared with that of homologous observation stations. The conclusions are as follows:the multipath error of the B3 is lowest ; the multipath error of the GEO satellite is less than that of IGSO’s and MEO’s in the three constellations;there is no significant difference in the multipath errors between the GEO and the IGSO;compared to the multipath error of GPS, the result of B3 is slightly better than the results of GPS three frequency points,the results of B1 and B2 are equivalent to that of the L1 and L2 in accuracy.

By analyzing the multipath (MP) combination of BDS-2 satellite, the code bias of BDS-2 satellites is confirmed as elevation, satellite, and frequency dependent. For BDS-3 satellites, the MP combination is calculated and the elevation-dependent model is developed for each satellite on different frequencies by the polynomial fitting method. The observation data of BDS-2 satellites are from IGS station JFNG, while the data of BDS-3 satellites are from self-test data SGG0. The results of BDS-3 satellites show that the code bias is ignorable.

In this paper, several key techniques of ground-based GNSS water vapor tomography are optimized using ERA-Interim reanalysis data. First, a regional atmospheric weighted mean temperature model is established using atmospheric products provided by ERA (each-re-analysis)-Interim. We give the humidity conversion factor, which varies with time and surface temperature. Then, based on the high vertical resolution water vapor products provided by ERA-Interim, we analyze the law of the change of water vapor stratification roof with time, and propose a new method to divide the vertical grid. Data from 12 CORS stations in Hong Kong, China in June, 2014 are selected for trial. The experimental results show that compared with conventional tomographic results, the precision of the optimized tomography results is 12% higher in areas under 6 km and 17% higher in areas greater than 6 km.

We firstly derive the algorithm to retrieve the true cloud location and cloud top height by use of the FY2 stereoscopic observation, and the algorithm to compute the apparent cloud parallax from the true cloud location and its cloud top height. Based on the geostationary satellite stereoscopic algorithm, a simulation is performed on the distribution feature of the apparent cloud parallax and the relationship between the apparent cloud parallax and the cloud top height under two cases of FY2 stereoscopic observation. The analysis shows that the linear model may cause larger errors that cannot be ignored near the conjugate region edge. We accordingly propose a nonlinear cloud height retrieval algorithm which could be used on the full region of stereoscopic observation. The average height resolution is about 1.28 km for 86.5E/104.5E and 0.93 km for 86.5E/112E, when the spatial resolution of the applied data are both 0.01 degree. The combination of 86.5E/112E has better height resolution than 86.5E/104.5E. A stereo cloud height retrieval test is performed to a case from the northwest Pacific and the test results are compared with the CTH observed by Cloudsat CPR microwave radar.

When GNSS outage occurs in a land vehicle GNSS/INS integrated navigation system, INS navigation error will be cumulated quickly. In order to improve positioning precision and integrity, odometer speed information and non-holonomic data are utilized to aid the integrated navigation system. We derive the output model of the odometer in consideration of the scale factor error of the odometer and the misalignment angle of IMU. The model, based on Kalman filter for the GNSS/INS integrated navigation aided by odometer, is deduced. A vehicle experiment is performed to verify the proposed method. The results show that the odometer can effectively restrain the error divergence of the navigation system. In case of GNSS outage of 60 s or 10 minutes, the positional accuracy is increased by more than 90%.

In order to get accurate 3D geometric information of the tunnel, the extraction of the central axis of the tunnel plays a key role. Firstly, the data of the tunnel point cloud are pretreated and divided into different sections according to the direction of the tunnel. Then, the less accurate central axes are extracted according to the vertical relationship between the axes and normal line of the surface point cloud. Finally, the more accurate axis is extracted by using cylindrical multi-segment fitting. The experimental results show that the proposed method has good applicability to straight and curved circular tunnels, and the algorithm is reliable and accurate.

When solving EIV model for the three-dimensional small-angle coordinates transformation, the weight matrix of observation vector and coefficient matrix may be inaccurate because of the difference between their unit weight variances. So, the Helmert variance components estimation method is applied to resolve the problem with posterior estimation in the weighted total least squares (WTLS). Thus, the weight matrix of observation vector and coefficient matrix should be redistributed, so that the calculation model will be more reasonable. The calculated example proves that the new method can improve the precision of the coordinate transformation parameters and the parameter estimations are closer to true values.