Gravity changes in the earthquake source area and the surrounding area before and after 1 month, 6 months and 1 year of Japan MW9.0 earthquake on March 11, 2011 were calculated by using GRACE RL05 time variable gravity field models.We find that a plus or minus alternate phenomenon is more obvious within 1 year before the earthquake. By calculating the coseismic gravity changes based on the earthquake dislocation theory and these of upward continuation to the satellite altitude, the results show that the coseismic gravity changes of the earthquake can be clearly detected by the GRACE satellite. Combined with the GMT best double couple focal mechanism, time series gravity changes of four feature points in the surrounding region are analyzed. We find that dynamic change status of surrounding material of the focal region revealed by the two methods are consistent.

In order to find out the characteristics of crustal material migration in Shanxi rift and its adjacent areas, we got the crustal material density changes based on gravity variations from 1999 to 2008 in the area of Shanxi province, the weight with depth and flatness of the model are taken into account in the inversion process. The result showed the basic characteristic that material accumulation locates in the region of Lüliang Mountain and the middle of Linfen Basin, and material loss locates between the Taihang mountain and the centralsouthern Shanxi rift.

We use the leveling data from 1998—2006 to analyze the dynamic characteristics of land subsidence in Tianjin. The results show that the land subsidence is larger in south of Tianjin than that of north, which the subsidence rate is very small from north boundary of Tianjian to 39.3°N, and the subsidence rate is large from 39.3°N to the south boundary. The results of multisection reveal that the subsidence rate is large in the east region of middle Tianjin from 1998—2002, while it decelerates from 2002—2004 and it increases from 2004—2006.

In order to reduce the influence of EI Nio event on polar motion prediction, the length selection of polar motion fitting series are studied for polar motion prediction. The results show that the accuracy of polar motion prediction can be improved in the time of EI Nio by extending the length of polar motion fitting series to 17-19 years.

The satellite laser altimetry elevation change time series are constructed using Envisat observation from October, 2002 to September, 2007. The elevation change over Enderby Land region of the Antarctica is constructed by the improved dynamic cross over analysis method. The result shows  that there is obviously positive in this area during 20022007, which is up to 6 cm/a.

Several earth gravitational field models are compared and analyzed based on the GPS/leveling data, which are distributed over not only Guangdong region but also densely over two local areas. The result shows that the accuracy of the EGM2008/ EIGEN6C（1420） model is the highest with 0.066 m in Guangdong region.

The tectonic structure and seismicity were analyzed by the space distribution of earthquake, the water level changes and focal depths of seismicity. The result shows that the earthquakes are mainly distributed in the Dongrangkou, Huofeng, Xietan area, and along the Gaoqiao fault and Xiannüshan fault. In the Dongrangkou and Huofeng areas, the earthquakes are mainly caused by Karst collapse. And for the earthquakes in the Xietan area, they are closely related with landslid and coal mine, and the genesis can be contributed to the mine collapse and superficial unloading. Whereas, those earthquakes along the Gaoqiao fault and Xiannüshan fault are mainly caused by the structures.

This paper overall analyzes and summarizes all kinds of errors and their effects on the realtime singlepoint velocity determination using the carrier phase changerate. Then we verified verifies the accuracy of velocity by a static station’s observations processed in kinematic mode, and the result shows that the horizontal component of the velocity can reach several millimeters per second and the vertical one is better than 1 cm/s by using the carrier phase changerate and realtime singlepoint velocity determination of broadcast GPS orbit.

The real time regional ionospheric TEC is modeled using the ionospheric residuals combination observations and the low order spherical harmonic function, 14 IGS stations from Europe are chosen as a net, a VTEC model is calculated every 15 minutes, which is also applied to the experiment of singlefrequency PPP. By comparison with the CODE model, it shows that the difference of the VTEC is less than 2 TECU, the 95% accuracy of forecast model is less than 1TECU. In the test of singlefrequency PPP, the positioning results have 17%-30% improvement in the zenith direction and 15%-30% in the horizontal direction.

The IGU ultrarapid satellite clock provided by IGS can not meet the demand of the realtime precise point positioning (PPP) at present, the method of realtime clock estimation based on the IGU prediction orbit in the regional IGS net is proposed and the positioning precision of the realtime clock estimation using PPP is analyzed. Results show that, the RMS of difference between realtime clock estimation and IGS post precise clock product is less than 0.1 ns; compared to IGU prediction clock, the PPP precision improves 87.1%, 81.8%, 913% respectively in X, Y and Z directions when using the realtime estimated clock, and its 3D precision improves 87.4%, and the precision of realtime PPP can reach cm, the convergence time is shortened in half.

The computation and the accuracy and running time of Lagrange interpolation, Newton interpolation, Neville successive linear interpolation are compared.The result indicates that each algorithm is feasible within the required accuracy range, but it is easy to produce Runge phenomenon in Lagrange interpolation. Coefficients of the interpolating polynomial algorithm is about 45 times faster than Lagrange interpolation and 15 times faster than Newton and Neville interpolations at 50 Hz sampling rate interpolation experiments.

Extreme Learning Machine (ELM) is employed for predicting satellite clock error. The impact of activation functions on prediction accuracy using ELM is analyzed, including Sigmoidal, Sine and Hardlim functions, and ELM model is compared with the grey system model and radial basis function (RBF) neural network(NN) model. The results show that prediction precision of ELM algorithm is best, and can learn faster than RBF neural network. Moreover, the Sigmoidal activation function is best for clock error prediction.

In order to analyze the interference of ultra high voltage (UHV) transmission line on the GPS signals, several GPS stations with different distances to the first 1 000 kv UHV transmission line in Hubei province were constructed. Both live and offline GNSS observations were captured, and then were extracted with the same satellites. According to the GPS orbiting regularity, by using the software TEQC, the multipath of P1 and P2, signaltonoise ratio of L1 and L2, and data perfectness ratio of GPS observation data were analyzed. The results indicated that the obvious interference of the UHV AC transmission line to the GPS signals with difference distance had not been found.

The paper compared and discussed six commonly used interpolation methods. The interpolation methods were evaluated using the parameters such as the root mean square prediction error and the source data root mean square, within different experimental areas in the Antarctica. The result showed that the Kriging interpolation method is more suitable for constructing the Antarctic ice sheet DEM.

Ten gravity field models up to 60 degree and order  are recovered based on one year GOCE orbits data and short arc integral approach. The correlated error among spherical harmonic coefficients is studied. And the mass change within the range of Antarctic 30° is inverted using the recovery gravity field model sequences. The results show that the mass change at B point (-75°, 250°) is approximate -9.15 cm/a which is detected by GOCE satellite, it means that the ice sheet of B point is melting.

The GPS ICD document defined a new group of 18 parameters broadcast ephemeris model, according to the user algorithm of this new parameter model, the partial derivative expression of each parameter is derived, and the linear function model is established between the 18 parameters and satellite position vector. In order to test this algorithm, the Beidou satellite orbit determination data are used to calculate the 18 parameters of Beidou satellite broadcast ephemeris by the principle of leastsquares adjustment. The result verified the correctness of the algorithm, and simultaneously proved 4 hours fitting error is better than 0.01 m.

The separation between geoid and quasigeoid by using observed gravity data and SRTM3 terrain data in some areas of QinghaiTibet plateau was determined. Theory analyses and numerical tests showed that there existed a high correlation between the separation and elevation, and the average correction about first order height terms could be up to 1.76 m, and the maximum correction about second order height terms could be up to 0.03 m.

This paper uses distributed computing technology to achieve parallel processing of the Bernese 5.0 GPS software based on the Bernese processing engine, and we overcome the disadvantage of scale limits and poor timeliness of GNSS observations in a single computer. Then,  the viability and superiority of this method are validated through precise point positioning and doubledifference network solution.

The tropospheric zenith delay was analyzed through the one year of Hong Kong CORS system using GAMIT software, and a tropospheric zenith wet delay correction model was constructed according to the Hong Kong weather elements for the parameters, then we embedded it to the TRACK module. The result showed that the TRACK module improved the accuracy of GPS measurements by using the new model when comparing to the traditional Saastamoinen model.

Based on the QIF and MW methods, a large number of measured data formed different length baselines are calculated to analyze the applicability of the two methods for different length baselines. The results could provide a criterion to select the method of ambiguity decomposition.

We present conjugate closer registration algorithm based on the residuals iterative for the shortcoming of obtain higher registration accurate under the condition of fine scan to few conjugates. The error decomposition of the conjugates by coarse scanning based on the sixparameter model. The target same points are closed to reference conjugates through transfer registration error to the same point by coarse scan. The conjugates of the two coordinate achieve the degree of overlap, and at last realize the process of fine scanning for coarse scanning. The feasibility of the method is verified according to the conjugates’ data which is obtained by fine scanning and coarse scanning to multiple stations.

In order to unify existed foundation geographical information data under the new datum,we designed the coordinate transformation flow between vector data and raster data, and developed a  software to achieve highprecision coordinate conversion for shp format and tif format images on the base basis of GDAL. Experiments show that the results transformation image data are consistent with the accurate known data, which can be concluded that the methods are correct and useful.

In order to optimize the unwrapped result of those mask areas, an improved maskcut phase unwrapping algorithm is proposed. After the mask generation, those nonmask areas are unwrapped directly, then the “circle cancelling” method is performed during those mask areas to minimize the discontinuity, which can remove those “died area” and keep the unwrapped result continuous. The tests performed on InSAR and InSAS interferograms show that the improved algorithm removes the “died area” of the unwrapped result successfully and greatly enhances its quality.

The theoretical formulas and steps of the tilt tide, gravity tide, strain earth tide,which divided into four partial wave: long period wave, wave, semidiurnal wave, 1/3 wave were given by the Laplace series expansion method. The above theoretical values can be calculated using C # programming language, and compiled into a dynamic link library. The results can be used as a crossplatform and crossoperating system calls.

In AutoCAD, clothoid can be fitted only by short straight lines, which cannot be modified and queried, and this method is inefficient in calculation and drawing. The series expansion integration method is improved to ensure the accuracy and efficiency of calculation. With the techniques of ObjectARX custom entity and objectoriented programming, the custom clothoid class is derived from the curve base class. The programming methods for drawing, modifying, querying, storing and dragging of the custom clothoid are stressed and the accuracy control method is discussed. The experimental results show that the above methods can develop the programs for custom clothoid efficiently, which can solve the problems caused by fitting and implement the graphicoriented design.

In order to investigate the detection capability of conventional measurement techniques in the dynamic load test,  Trimble R8 GNSS/RTK technology, TCA2003 automatic tracking 3D coordinates measurement and SPRINTER 200M digital leveling are applied to synchronously monitor the deflection displacement of a damped oscillation, which has a designed frequency of 0.5 Hz and mm level amplitude in this test. Based on the FFT algorithm, spectral information was independently calculated out from these observed data, this paper makes a comparative analysis combined the dynamic deflection. The results show that the TCA2003 automatic tracking measurement techniques can accurately measure and truly reflect the characteristics of the dynamic deformation; the SPRINTER 200M digital leveling can monitor the overall trend of dynamic deflection, but only get a certain harmonic frequency; and GNSS/RTK technology could only acquire a certain harmonic frequency.

Quadratic model is fitted with the nearest history data of 24 hours when the satellite is outofview, and is used to predict clock offset as soon as the satellite is in view. Based on the conventional fit algorithm, the best fit arcs are selected independently for the two fitting parameters of frequency bias and frequency drift according to their respective characteristics at different length of fitting arcs. A twostep fit is proposed using both longand shortterm data sets. The fit and prediction comparisons using the real clock offset data show that the prediction performance of twostep fit is better overall than the conventional method.

According to the relationship between the phase biases and precise point positioning(PPP) model in ambiguity resolution, the estimation model for phase biases is derived based on the directional statisticsnd, and the ambiguity fixing scheme for PPP is designed which can solve the problem of ambiguity fixing for PPP. The results show that, based on phase biases correction, the convergence speed of PPP ambiguity fixed solution is improved by 3/4 compared with floating solution, the Ratio value is improved by three times, and positioning accuracy is also obviously improved.

The GPS data of collocation survey between the GPS and VLBI stations at the Nanshan stations of the Xinjiang astronomical observatory in August, 2011 were used to discuss the layout and observation, data processing method and the measurement accuracy of GPS control network, and coordinate transformation between the GPS measurements and optical measurements in the monitoring network.

Due to external factors such as waves, hurricanes and ship collision, crosssea bridge deformation shows the dynamic nonlinear state, there is also a chaotic phenomenon. Therefore, db10 wavelet threshold denoising and soft law are used to break down and eliminate the gross errors in the data distortion and noise. Phase space is reconstructed by the smooth deformation of the timeseries after wavelet pretreatment, the bridge chaos state is determined by Lyapunov indices, and chaotic time series prediction and exponential smoothing forecast are analyzed and compared, it is proved that chaos prediction has reliable and high precision.

In order to analyze the change law and tendency of height data of IGS continuous operation reference station and predict the future changes of the height data over a period of time, based on the theories of RBF regularization neural network and wavelet filter neural networks, the height component data of Beijing IGS station is dealt with the GRNN function approximation and wavelet decomposition approximation on the basis of the MATLAB7.0 platform. According to the fitting historical height data and hierarchical filtering, the seasonal changes were found in height time series, and seasonal changes included half year cycle changes and year cycle changes, and the year cycle was obvious.

To counter the characteristics of Beidou navigation satellites’ large clock error and signaltonoise, a suitable combined method for cycle slips detection and correction is proposed. Firstly, the limits of two frequency cycle slip can be determined by the combination of singlefrequency and code, then the least squares polynomial fitting would be performed based on dualfrequency data considering the change rate of carrier phase. The cycle slips would be demarcated and outliers would be rejected by the Blewitt method to test fitting results. The cycle slips, being an integer, can be restored by means of minimize the residuals. The test on COMPASSMEO satellites’ data verifies that the proposed algorithm can detect all cycle slips and fix it quickly in static and lowdynamic measurements.

The accuracy estimation of the determination of the calibration factor of a superconducting gravimeter using an absolute gravimeter is discussed in detail. Possible factors affecting the accuracy are analyzed. The result indicates that it can minimize the accuracy to choose the observation period as the large tide period. The linear instrumental drift must be deducted before calculation, and the time shift must be checked and corrected. As an example, the calibration experiment at Wuhan station using an absolute FG5112 gravimeter to calibrate the GWRC032 superconducting gravimeter shows that it is comparatively difficult to achieve a relative calibration accuracy of 0.1%, which need very long time absolute gravity data. However, a relative calibration accuracy of 0.2% can meet the requirements to calibrate most of the superconducting gravimeters, and this accuracy can be reached using about 5 days absolute gravity data.

A modeling method based on the BP neural network is proposed for correcting pointing error of the satellite laser ranging telescope. This experiment makes use of the three groups of stars data observed in Wuhan mobile satellite laser ranging station to calculate and compare root mean square errors by respectively establishing BP neural network model, mount model, spherical harmonics model and basic parameters model. The results show that BP neural network can be applied to pointing error modeling, and modeling accuracy is higher than other three models.

The observed rotor current data of maglev gyro total station directional system can be described as a kind of nonlinear data series relating to time and environment. Practical results show that, by using wavelet decomposition and reconstruction, this method can efficiently extract directional rotor current characteristics from the observed data series which were disturbed by strong noises. Moreover, comparing with traditional processing techniques, it has excellent features for nonstationary and nonlinear rotor series data filtering in directional system. It can effectively improve the instrument orientation results, and also improve the precision of directional angle.

A photoelectric bimetal tube is developed successfully based on the principle of bimetal tube. This instrument is applied to the vertical displacement monitoring system of the Tingzikou hydropower dam. The results show that the instrument operation is stable and reliable, and monitoring effect is good.