In this paper, a global gravity field model entitled TJGOCE01 up to the degree and order 250 is recovered from about 6 months of GOCE gravity gradient data and 12 months of GOCE orbit data, using a direct approach. The gravity gradient data are filtered by an infinite impulse bandpass digital filter, and gross errors are detected and removed using the threshold and a moving window threshold methods. The gravity gradient observational equations are established in the gradiometer coordinate system directly and the kinematic orbit observation equations are established by using a modified short-arc approach. The weights of the two kinds of observations are determined based on their prior accuracies, and the regularization approach based on Kaula’s rule is applied to solve the normal equation. The geoid error and cumulative geoid error up to degree and order 250 of TJGOCE01 model with respect to EIGEN6C2 model are 19.4 mm and 177.9 mm, respectively. The test results with the GPS leveling data in North America show that the root mean square error of TJGOCE01 model is 0.544 m, which is superior to the second generation models developed by the European Space Agency using time-wise and space-wise approaches.

This paper studies the issues of linearization errors in regional gravity field modeling and introduces the high-order global gravity model as reference gravity field to reduce the corresponding linearization errors. As an example, we analyze the effects on regional gravity field modeling introduced by different reference gravity fields. To do so, we use Poisson wavelets radial basis functions based on terrestrial and shipboard gravity anomaly andon airborne gravity disturbance. The results show that the incorporation of global gravity field model, instead of GRS80-derived normal gravity field, as the reference gravity field leads a better approximation of the real gravity field. The corresponding linearization errors are also reduced. Compared to the quasi-geoid computed from the GRS80-derived normal gravity field, the accuracy of the quasi-geoid based on DGM1S-derived reference gravity field is improved by 1.5 mm, 3.3 mm and 9.0 mm at Germany, England and Norway respectively, where the topography show more undulation.

The combination of EMD and wavelet analysis is used to detect the period of VTEC. The possible period of ionospheric activity is detected by analyzing the IMFs under multi-scale with wavelet analysis. The probability can be increased with this new method. The VTEC series at different latitudes released by IGS is used as an example. The feasibility and validity of the method promoted in this paper is proven. The possibility of 6 d, 24 d and others is discovered and a new approach is proposed for period detection of VTEC.

This paper calculates slip and pressure amounts and the cumulative amount of change for studying the fault activity characteristics in the Yunnan region, using the cross fault baseline and leveling observation data from 1982 to 2013. Combined with analyzing earthquakes at magnitude 7 and above in this region, the results show that there are obvious segmentation features during the time of fault activity in the Yunnan area, and that there are obvious differences in space activity. The relationship between faults and earthquakes mainly shows that: when the pre-earthquake fault activity is enhanced, the coseism fault activity can be changed, and the after earthquake, activity will be weakened or strengthened.

In this paper, we inversed for the slip rate and spatial fault locking of the Anninghe-Zemuhe-Xiaojiang fault zone based on a negative dislocation with horizontal GPS velocity data from 1999 to 2007 and 2009 to 2014. Using the inversion result and the historical earthquakes, we analyze the potential for a large earthquake. The result shows the Wenchuan earthquake enhanced the locking of Xiaojiang and the middle segment of Zemuhe, but didn’t affect the locking of Anninghe or the southern and northern segment of Zemuhe. Moreover, the northern section of Anninghe, the southern and northern segment of Zemuhe , the southern segment of Xiaojiang are strongly locked before and after the Wenchuan earthquake, with a locking depth of more than 20 km. Considering historical earthquakes and other results, we conclude that these segments are seismogenic faults with large earthquake potential.

In order to inspect the change form of schema transformation and the stress form of Hetao seismic stress field, we use amplitude ratio and CAP methods to calculate 224 focal mechanism solutions, based on normalized frequency statistics and analysis of fault slip type.The results show that the advantage distribution of compressive stress orientation is NE, the advantage distribution of tensile stress orientation is NW, and the rake angleis distributed nearly horizontally. Further, the whole stress field shows inheritance features, horizontal shear and tension control the stress form of faults in Hetao seismic belt, and the main outputs are strike-slip type earthquakes. Throughout the whole study period, a steady stress model is presented. Combining peripheral dynamic properties withregional tectonic movement determines that, under the joint action of the westward subduction of the Pacific plate and the Qinghai-Tibet block northward migration, Yinshan uplift and Ordos block relative to do spin twist.Finally, the NE-EW distribution faults present horizontal and rotary shear, and constitute a relatively stable evolution model of stress field.

We analyze the relationships between filter bandwidth, density of stations in the study area, threshold for correlation coefficient, and recognition rate. We also discuss the differences between “repeating events” by cross-correlation of seismic waveforms and the overlap of rupture zone semi-quantitatively. The results indicate that: more stations, local earthquake data, a 0.2-20 Hz bandpass filter and a detection threshold over 0.8 should be used. Furthermore, if MS≥4.5 for two repeating events, there is at least some overlap between their source zone.

The soil radon (Rn) concentration of the Macheng-Tuanfeng fault has been measured through radon measurement. A comparison of the measuring results and regional geological section leads to discussions of the geographical location, scale and occurrence of the Macheng-Tuanfeng fault. The result reveals that the major fault generally strikes NNE across the Fuzihe town and Yanjiahe town, dipping north and with a high dip angle, and the width of fracture zone ranges from tens of meters up to one hundred meters. Combined with the measured data and the available soil radon appraisal methods of fault activity, we consider that the Macheng-Tuanfeng fault still has a high level of activity. The data also indicates a soil radon anomaly with an imbalance between south and north; we supposed this for two reasons: 1) the activity of the Macheng-Tuanfeng fault presents a weakening tendency from north to south; 2) due to the Macheng magnitude 6.0 earthquake, the release rate of radon gas has increased near the earthquake area.

This article takes time of observation into account on trend surface fitting, as a dynamic trend surface fitting model. The land subsidence data from the GPS monitoring system of Nansha is analyzed using the dynamic trend surface model.  Our results indicate that the model could reflect the overall tendency of the settlement and have good spatial interpolation effects.

We construct the hyperbolic curve model and then use the least square method to obtain its parameters. These parameters are regarded as state vectors to contain dynamic noises to erect a Kalman filter model based on the hyperbolic curve model. On the basis of this model we forecast settling amounts of the building. Since the parameters of the Kalman filter model change continuously, its ability to suit the observation data is increased, and the fitting error of the model is reduced. An example of calculation shows that the forecast error is small, and this suggests that it is best to use the Kalman filter model based on the hyperbolic curve model to forecast settling amounts of the building.

This paper uses discontinuous deformation analysis and FEM to study the earthquake response analysis on masonry structures. In the modeling process, the bricks, columns, lintels and floors in the masonry structure are regarded as independent elastomer. Each elastomer is classified as a finite element. Movement among the elastomers is based on the opening, closure and slide control of the contact interface. To prevent the intrusion of elastomer we correct the results of least-square of displacement and strain to the simulation system. We use Coulomb-Moore’s law to control the function and failure of mortar’s forces among elastomers. We input the peak acceleration equal to the seismic intensity of  Ⅸ degrees of Qianan wave in the masonry structure model for dynamic analysis and to study the whole seismic response process. The analysis of the example shows the methods of DDA and FEM can simulate the dynamic response process of masonry structure subjected to earthquake very well. Under the effect of a large earthquake, the bottom of masonry structure firstly began to show cracks and then led to structural collapse. This agrees with the earthquake damage phenomena seen in rural masonry structures in real large earthquakes.

Based on the relationship between multi-path and SNR, in this paper we give the basic principle of GPS-MR based SNR to detect snow depth. Data in P360 are used to verify the validity of GPS-MR. The result is in good agreement with the measured snow depth data, and the correlation coefficient is greater than 0.97.

In this paper, considering the geometric TCAR (three carrier ambiguity resolution) algorithm, BDS/GLONASS mode is brought into wide lane and narrow lane calculation. Then the model of single epoch and multi-frequency BDS/GLONASS RTK positioning is presented. The mathematical model and its feasibility are verified with the measured data, and the result shows that compared with other models, the proposed model is optimal in ambiguity resolution efficiency and positioning accuracy.

To analyze its influence, 6 sets of experimental network are selected based on the CORS of America. The averages of the height and distance between the stations in the experimental network aredifferent from each other. By applying GAMIT/GLOBK data processing software, we analyze the impact of the height difference on the baselines solutions from 4 aspects, including comparisons with the true baselines values, baselines repeatability, NRMS and precision. The results show that it will bring about 1 cm error in the ‘up’ component of the baselines solution, if the height difference between stations is more than 100 m. However, the error can be decreased to 1 cm if a tropospheric delay parameter is introduced. In this way we can get a high precision baselines solution.

This paper compares the comprehensive noise of code-phase combination and phase integer, which considers ionospheric delay, choosing the minimum noise combination (1,－3,2) and the combination (4,－3,－2),in which the sum of coefficient is unequal to zero. It combines the combination of (0,1,－1) to detect and correct BDS triple-frequency cycle slip. Analysis with BDS triple-frequency data provided by IGMAS considers three differenced constellations, which validates the hypothesis that it is possible to detect and correct all kinds of undifferenced cycle slip in real time.

This paper is concerned with the problem of suboptimal and divergence in distributed filtering for autonomous orbit determination of satellite navigation systems. This paper proposes a concentrated filtering method, in which the navigation satellite constellation is considered as a whole, and essentially, theories of pseudo-inverse adjustment and spacecraft dynamic orbit determination are combined. First of all, differences between free network adjustment of geodetic survey and that of spacecraft network are discussed.Then a method of satellite constellation orbit determination which combines pseudo-inverse adjustment theory and satellite orbit dynamics is constructed, and the relevant technological process is given primarily. Finally, an example of network of typical walker constellations is given. The simulation results show that the user range error (URE) of any satellite is less than 0.8 m, mean URE of the satellite network is less than 0.5 m after five days’ autonomy operation.This verifies the efficiency of the method.

This paper studies a pedestrian navigation algorithm based on zero velocity update(ZUPT) aided MIMU. Considering the problem of the increasing error of MIMU over time,according to the assumption that the pedestrian’s velocity can maintain zero in a short time in every foot stance phase,the virtual noise observations are constructed to estimate system error. Noting that the zero-velocity detector is the key technology in ZUPT,we compare four detectors and evaluate their efficiency and accuracy.The four detectors are the acceleration moving variance detector, the acceleration detector, the angular rate detector, and a combined detector.The experimental results show that under the circumstance that the distance is short and step is slow,the four detectors can all reach high accuracy. However, the combined detector give the highest performance.

In this paper, the similarity transformation method and the strong constraint method are used in processing the extended 260 CGCS2000 skeleton points with the GAMIT/GLOBK software. Coordinates of stations in the ITRF2008 are obtained through adjustment calculation adopting three schemes. The comparison result of the three schemes shows that different constraints on the original data will result in different positioning precision, and that inappropriate constraints may lead to network deformation and distortion with the strong constraint method. The similarity transformation method is more reliable and can avoid the above-mentioned problems. Its average mean square error is less than 1 mm.

This paper analyses the CG-5 gravimeter’s drift characteristics from dynamic and static drift rate bases on large experimental data. Our research shows that the CG-5 gravity meter’s zero drift rate is comprehensively high, its variation magnitude becomes smaller as time goes by, but trends to stable eventually; the dynamic and static drift rates show a general trend of decrease as spatial latitude increases (gravity reading section increase),but with significant individual variations.

The quadrature coupling error of broadband electrostatic feedback tiltmeter is analyzed and calculated. It is shown that quadrature tilting has a negative influence on measurement results. Measures should be taken to reduce quadrature coupling error.