Using StaMPS technology, based on the images of 133 ascending orbit and 95 descending orbit covering Beijing capital international airport from 2017 to 2021, we research the ground subsidence around the airport and the stability of cracks in the interior of the site. The results show that the image monitoring results of ascending and descending orbit are in good agreement. A subsidence funnel is formed in the south of the airport and the south of the Wenyu river. The maximum deformation rate inside the funnel is over 40 mm/a, and the subsidence funnel is distributed along the Wenyu river. We verify the internal coincidence accuracy of the monitoring results of the ascending and descending orbit images. The results show that the deformation rate difference of more than 90% common pixels is between ±10 mm/a, which proves the consistency of the monitoring results of the images. The time series deformation results of feature points show that the subsidence near Jinzhan township, Fuhao village and Huangjinhuayuan community is serious, and the maximum cumulative shape variables exceed 250 mm, 150 mm and 110 mm, respectively. It can be seen from the overall deformation results of the airport and the time series and profile results on both sides of the ground fractures that the difference deformation of the surface on both sides of the ground fractures is significantly compared, and the boundary of the deformation difference is more consistent with the location of the ground fissures.

In this paper, the glacier deformation is obtained by using offset-tracking technology as a supplement to SBAS-InSAR, and the pre-disaster deformation of Sedongpu basin is calculated by using two technologies from January 2018 to October 2018, and the pre-disaster deformation characteristics and influencing factors are jointly analyzed. The results show that the glaciers and gullies in Sedongpu basin were deformed before the ice avalanche occurred on October 17, 2018. The trend of the main deformation area of glacier is first accelerated, then gentle and then accelerated, with the deformation of -7.69 m from July to September. The sediments in channels showed a long-term downward trend, and the deformation rate accelerated after July. The temperature rise is the main factor for the occurrence of debris flow disaster. The combination of SBAS-InSAR and offset-tracking can meet the monitoring requirements of different deformation magnitudes, and can be used for early identification and deformation inversion of ice avalanche disasters, providing a reference for ice avalanche disaster prevention and control in the Tibetan plateau.

To improve the positioning accuracy of mobile intelligent terminals, we analyze the observation data of multiple satellite systems collected by Xiaomi Mi8 and Huawei Mate20 smartphones, estimate the parameters of signal-to-noise ratio model based on pseudorange residuals of different satellite systems, and finally carry out the static pseudorange single-point positioning experiment. The results show that the pseudorange accuracy of BDS and GPS observed on mobile phones is close to each other and is higher than that of GLONASS. The correlation between pseudorange residual and SNR is stronger compared to elevation angle. In the parameter estimation of SNR model, the fitting effect of Xiaomi Mi8 is better than that of Huawei Mate20. The fitting effect of BDS is worse than that of other satellite systems, and the horizontal positioning and elevation positioning accuracy of SNR model after parameter fitting are 2.37 meter and 8.38 meter, respectively, which is about 10% higher than that of elevation model.

We propose a gait recognition model that fuses long short-term memory(LSTM) and convolutional neural network(CNN), the model can automatically extract activity features and classify them using a small number of model parameters, and we utilize this model for user identification.  The experimental results show that the recognition accuracy of the model is about 97.68 % and the loss value is about 0.05, which significantly improves the recognition rate compared to other models.

Considering the high stability of high-performance hydrogen clocks and the strong correlation between clock offset series epochs, the receiver clock offset with additional prior information constraint is tested for precise point positioning(PPP) timing. The results based on B1C/B2b combination of BDS-3 show that compared to traditional timing models, the precision timing models with additional prior information have higher timing performance, especially for the short-term stability which has an improvement up to 60%. In addition, the PPP accuracy of B1I/B3I and B1C/B2b combinations of BDS-3 is basically equivalent, which can achieve positioning accuracy better than 0.5 cm and about 2 cm in horizontal and vertical direction, respectively. Owing to the better observation data quality of B1C/B2b, the positioning accuracy is improved by 13.8% compared to the B1I/B3I combination.

Using least squares and iterative algorithms for 5 d simultaneous co-location comparison observations at Anqiu seismic station, we process the data of A10-057 absolute gravimeter, FG5-265 absolute gravimeter and superconducting gravimeter(iGrav). The final calibration factor factors of FG5-265 and A10-057 precision measurement iGrav-053 are -883.929 4 ns^-2/V and -884.134 ns^-2/V, respectively, and the calibration accuracy is 0.048 26% and 0.093 7%, which are better than 0.1%. At the same time, we compare the differences between the calibration work of FG5-265 and A10-057 in terms of various measurement indexes and the selected measurement logarithms on the calibration results, and exemplify the requirements of calibration factor for multiple scenarios, which finally proves that the A10 model absolute gravimeter has the capability of calibrating relative gravimeters and provides a reference for the subsequent calibration of relative gravimeters.

We constructed models for changes in atmospheric and terrestrial water mass in the Three Gorges region. Then, using GNSS, GRACE-FO, and environmental mass change models, we calculate and analyze the vertical crustal deformation caused by environmental load from 2019 to 2022 in the region. At last, we discuss the differences in calculating environmental load vertical deformation using the spherical harmonic method based on GRACE-FO data and Green’s function method combined with the mass change model. The research reveals the vertical deformation of terrestrial water load of the two methods exhibits a certain consistency in spatiotemporal distribution, but the mass change model shows higher accuracy and spatial resolution. We calculate the environmental total load vertical deformation at CQWZ and HBZG stations, based on the quality change model. The correlation coefficients between deformation and GNSS measured results reached 0.88 and 0.83, respectively. The vertical deformation rates of the crust in the Three Gorges reservoir area and Dongting lake basin from 2019 to 2022 are 0.5 to 0.7 mm/a and 0.6 to 1.5 mm/a, respectively. We attribute this to the decrease in water level in the region in 2022, leading to crustal rebound. The crust near the Three Gorges reservoir exhibits a pattern of rising in summer and sinking in winter, with vertical deformation amplitudes ranging from -5 to 18 mm, primarily driven by reservoir water storage and atmospheric load.

The original curve analysis method and normalized variation rate method were applied to analyze the data changes of four earth resistivity stations within 400 km of the epicenter of Maduo M_S7.4 earthquake on May 22, 2021. The following results were obtained:1)Before the Maduo earthquake, the data of four earth resistivity stations showed different degrees of anomalous changes, among which the original curve changes of the Maqu NW, Jinyintan EW, Ganzi N10°E, and Lanlongkou EW channels were the most obvious, which manifested hour value jumping changes, accelerated changes in the daily mean values and curve turning changes, as well as trend changes in the monthly mean values of the broken and preserved annual variation patterns;2)The normalized rate curves of Maqu NW, Jinyintan EW, Ganzi N10°E, and Lanlongkou EW all exceeded the threshold before the Maduo earthquake, but their respective normalized rate patterns are different;3)The comprehensive analysis concludes that the anomalous changes in the earth resistivity data of the four stations are related to the gestation and activity of the Maduo M_S7.4 earthquake.

This paper introduces the research progress, standardized test and experimental observation on seismic station of the JCZ series ultra broadband seismometer JCZ-360. The results show that the JCZ-360 ultra broadband seismometer can effectively suppress the influence of external atmospheric pressure, external magnetic field interference and temperature change on the instrument. Its performance is more stable and noise level is lower at the ultralow frequency terminal. The JCZ-360 ultra broadband seismometer can not only observe full-band seismic waves, but also record information such as solid tides and free oscillation of the Earth. It has the comprehensive observation ability of traditional seismic and traditional geophysical field.

To compare the positioning performance of the new signals and old signals of Beidou-3 satellite navigation system, we conduct a comprehensive evaluation of BDS-3 precise point positioning with new signals B1C/B2a using two-week observation data from 17 MGEX stations. The results show that the accuracy in E, N, U directions of static PPP with BDS-3 B1C/B2a was 1.3 cm, 0.8 cm, and 1.9 cm, respectively, while that of kinematic PPP was 2.6 cm, 1.8 cm, and 4.2 cm, respectively. The static positioning accuracy in U direction showed an improvement of 13.6% compared to the BDS-3 B1I/B3I combination, the accuracy in E, N directions were similar. In the kinematic mode, the accuracy in E, N, U directions were similar, with differences within 1 mm. In terms of three-dimensional(3D) error, BDS-3 B1C/B2a static PPP achieved centimeter-level accuracy within 40 minutes, while kinematic PPP achieved decimeter-level accuracy within 5 minutes. The static PPP with the dual-system BDS-3 B1C/B2a+GPS L1/L2 achieved centimeter-level accuracy in three dimensions within 20 minutes, while the kinematic PPP achieved centimeter-level accuracy within 30 minutes. Comparing with dual-system BDS-3 B1I/B3I+GPS L1/L2, the positioning accuracy and convergence speed are basically the same. Overall, the positioning performance of B1C/B2a frequency is superior to that of B1I/B3I frequency.

This paper collects dynamic data from low-cost receivers in three different speed ranges and analyzes the data reception capability, data quality, and navigation positioning performance of multi-system interoperable signals, B1C/L1/E1, and B2a/L5/E5a, within various speed intervals. The results show: 1) As the speed increases, the reception capability of interoperable signals gradually deteriorates. BDS-3 can maintain visibility of more than nine satellites on average. Among the interoperable signals, B1C/L1/E1 exhibits superior data integrity but is more susceptible to data interruptions.2) As the speed increases, the carrier-to-noise ratio of interoperable signals decreases, and cycle slip ration increase. However, the pseudo-range noise, carrier phase noise, and multipath effects are less affected by speed. Notably, B1C/L1/E1 exhibits minimal carrier phase noise and multipath effects. 3) The influence of carrier speed on positioning accuracy has no obvious regularity. The speed and the degree of environmental occlusion affect the positioning accuracy. The multi-system interoperability signals combination positioning has more improvement than the single system positioning performance; BDS-3 has high accuracy in the middle and low speed range, and its precision of PPP is better than other systems by more than 17%.

We use observation data from 5 GNSS/MET stations in Shanghai from July 21 to August 8, 2021 to invert atmospheric precipitable water vapor(PWV) by GAMIT software, and study the relationship between PWV and rainfall in Shanghai and the spatial distribution characteristics of PWV during typhoon “In-Fa”. The results show that the correlation between GNSS PWV and sounding PWV is above 0.9. Before the formation of precipitation, PWV undergoes three obvious rise processes and the precipitation generation time is about 60 h ahead of typhoon landfall.  PWV sharp change will cause a sharp rise or fall in precipitation. After the precipitation, PWV gradually drops below 40 mm. Before typhoon landfall, PWV is basically above 75 mm; PWV above 80 mm is mainly distributed in southern and central areas of Shanghai. After typhoon landfall, PWV is above 80 mm, and higher value areas can reach 90 mm. After the typhoon moved away, the PWV value dropped below 85 mm. The expansion and progression of the high-value area to the northwest is basically consistent with the typhoon path.

The solid tide signal of VP inclinometer is limited by the complex monitoring environment, which contains significant environmental noise. To obtain the real solid tide curve, we propose an improved complete ensemble empirical modal decomposition adaptive noise(ICEEMDAN) based on grey relation analysis for VP inclinometer to suppress signal noise. The method firstly uses ICCEMDAN to decompose the noise-containing signal to obtain several intrinsic mode functions(IMFs), which are sequentially arranged and labeled. Then, based on these IMFs, the evaluation indexes of correlation coefficients, mutual information, R², Adj-R², MSE, SSE, RMSE, MAE, MAPE, we compute sample entropy to construct a reliability evaluation index matrix of the IMFs. Finally, grey relation analysis(GRA) is used to calculate the correlation coefficients and degrees between various evaluation indexes and different IMFs. We sort the IMFs based on the correlation degree, and linearly reconstruct the top ranked IMFs to suppress signal noise. Both the simulation and actual denoising experiments show that the GRA-ICEEMDAN model is better than the classical noise reduction models, such as Kalman filter, 70 order low-pass FIR filter, and Savitzky-Golay. The noise component and effective component can be distinguished significantly, and the reconstruction error and original signal loss after decomposition are very small, so it can be extended to the signal noise reduction of other instruments.

Using seismic data of Jianghan-Dongting basin and its surrounding areas from historical records to 2021 to analyze the spatiotemporal distribution characteristics of earthquakes, we obtain the relationship between deep tectonics and earthquakes by using the hypoDD algorithm to relocate 788 earthquakes, and analyze the characteristics of tectonic stress field by using the P-wave first motion method to calculate the focal mechanism solutions of M_L≥2.8 earthquakes. The results show that earthquakes are distributed unevenly in space, the seismicity of basin boundary is stronger than that inside basin, and there is an obvious periodic rule of alternating quiet and active in time. The relocated earthquakes are distributed in clusters in NW and NE directions in Ningxiang, Shimen, Yuanan-Dangyang, Nanzhang- Jingmen, and Ezhou-Huangshi, and the seismogenesis of this five regions are closely related to fault tectonic activity. The type of focal mechanism solution is mainly thrust fault, the dominant orientation of P-axis is nearly EW, and its plunge angle is almost horizontal, the orientation of T-axis is mainly SN and NE, and its plunge angle is large. The horizontal collision between the Indian ocean plate and the Eurasian plate result in the formation of a nearly EW tension stress field in the Tibetan plateau, which pushes the basin eastward. In addition, the Philippine sea plate subducts northwestward and the Pacific plate subducts westward, resulting in the formation of a nearly EW compression stress field in the basin, which make the regional fault structure prone to vertical differential movement, and then led to the gestation and occurrence of earthquakes in the Jianghan-Dongting basin and its surrounding areas.

By fusing the observation data with the model，data assimilation provides an effective solution for realizing accurate mapping of physical and mathematical models to solid Earth as much as possible. We review the application and research status of data assimilation method in various branches of solid Earth geophysics, and make a preliminary discussion on the urgent problems of data assimilation method in solid Earth geophysics.

We compare and analyze the scale factors of long baseline calibration and datum solution of 5 CG-6 relative gravimeters, and process the data of gravity network in Guizhou of CMONOC in 2022 and 2023 using different scale factors. The results show that the scale factors of CG-6 relative gravimeters vary over time, and the precision of processing results is better by using the datum solutionscale factor.

This paper is based on the AR products from CODE, GFZ, CNES, PRIDE Lab, and in-house AR products for the performance assessment of PPP-AR in terms of convergence time, time to first fix and positioning accuracy. The experiment uses seven-day observation data from 40 IGS stations in 2022 and precise products of each AR product. The results show that under the static solution mode with confidence level of 95%, five products have the most obvious improvement in positioning accuracy at the time of 1 h, which are 46.58%(3.4 cm), 41.10%(3.0 cm), 45.21%(3.3 cm), 34.25%(2.5 cm), and 41.10%(3.0 cm), respectively. In the simulation-kinematic solution mode, the positioning accuracy of the five products in the E and N directions can reach the millimeter level, and the accuracy of the U direction is slightly improved than that of the floating point solution, among which the accuracy of GBM product is the least improved, and 72.73%(2.4 cm), 47.37%(0.9 cm) and 5.41%(0.2 cm) were increased in E, N and U directions. WUM and COM products had better improvement effect. They were 81.82%(2.7 cm), 63.16%(1.2 cm), 24.32%(1.1 cm) and 81.82%(2.7 cm), 63.16%(1.2 cm), 15.58%(0.8 cm).

The precipitable water vapor(PWV) retrieved by MODIS is continuous planar data, but the accuracy is not high. The PWV accuracy of GNSS water vapor detection technology is high, but it is discrete point data. Therefore, we combine the advantages of both, propose a MODIS water vapor correction method that combines inverse distance weighting and Fourier transform, and use GNSS PWV to correct MODIS PWV products. The GNSS data and MODIS water vapor products in Hong Kong are used for experimental verification. Firstly, the spatial interpolation problem is considered to make GNSS PWV and MODIS PWV consistent at spatial points. By comparing the accuracy of six interpolation algorithms with different MODIS pixel points, it is found that the algorithm with 5 interpolation parameters has the best effect, and the inverse distance weighting method has the highest accuracy, with an average deviation of -0.99 mm. Secondly, considering the water vapor correction problem, three models are constructed to correct MODIS PWV. It is shown that the root mean square error improvement rate of Fourier transform model can reach more than 70%. The MODIS water vapor correction method of the new model can weaken the influence of local data, and more accurately reflect the water vapor distribution in the region.

We process 69 Sentinel-1A satellite images using SBAS-InSAR from July 2018 to August 2019, and obtain surface deformation in Shuicheng district, Liupanshui city as dynamic evaluation factors to address the lack of dynamic feature data in traditional landslide susceptibility studies. The results show that, by fusing ten static evaluation factors and InSAR deformation feature data as dynamic evaluation factors, in a weighted information model coupled with analytic hierarchy process(AHP) and information volume method, the model performance improves approximately 13.3% compared to using only static feature data. The area under the ROC curves is 0.756 02 and 0.888 68, respectively. To assess zoning accuracy, we overlay historical disaster sites on two types of zoning maps. Compared to scenarios without the inclusion of deformation features, the introduction of deformation features corrected approximately 12.44% of misclassified areas, significantly enhancing zoning reliability.

The background noise of the second sampling data of four kinds of broadband instruments in Xinjiang during quiet period is analyzed, and the time-frequency characteristics of the signals recorded by various instruments under seismic waves and wind disturbance events are discussed. The results show that the noise level of RZB-2 borehole strainmeter is the best, and the response ability of VP type vertical pendulum to high-frequency signals(microseisms frequency range) is the best. Whether the instrument can record more geophysical signals or high frequency information is not only related to its own noise level, but also related to its response ability to the signal in this frequency band.

This paper introduces the methods and steps for estimating multi-GNSS multi-frequency code biases and validates the effectiveness of estimating inter-frequency code biases using a multi-GNSS ionospheric modeling approach. We compute daily solutions for various code biases using MGEX network observations from January 2019 to July 2023. We further analyze the accuracy of various code biases. The results indicate that the multi-GNSS multi-frequency OSBs calculated in this paper exhibit an average weekly stability ranging from 0.07 to 0.26 ns. Among them, the average weekly stability of BDS-2 and BDS-3 multi-frequency OSBs are 0.17 to 0.26 ns and 0.13 to 0.21 ns, respectively. The consistency of various types of DCBs with products from DLR and CAS can be maintained within 0.3 ns. This research is not dependent on external post-processing products and can calculate code biases with both a rapid turnaround time and high precision.

Starting from the theoretical basis of nonlinear adjustment precision evaluation, we review the current research status of the two types of precision evaluation methods. We describe the basic principles of the corresponding method and analyze the advantages and disadvantages of each method. In addition, we look forward to the research direction of nonlinear adjustment precision evaluation.

Based on the satellite orbit characteristics of BDS GEO, IGSO, and MEO, we use multi-point hemispherical grid model(MHGM) and sidereal filtering(SF) method to establish a multipath error correction model for a mixed constellation of BDS. After applying the model to correct multipath errors, the post-fit carrier phase residuals for BDS precise point positioning(PPP) are significantly reduced, and the positioning accuracy in E, N, and U directions is improved by 41%, 37%, and 38%, respectively, with an overall increase in convergence speed of 31%.

On August 23, 2023, the seismic instrument system of the Hongyanhe Nuclear Power Plant successfully recorded a M4.6 earthquake in Pulandian, Dalian. This is the first complete strong earthquake record around the nuclear power plant area in China. We analyze the seismic data recorded by the system, and the data playback shows that the seismic recorded data was clear and complete, and the peak value of the free field monitoring data is consistent with the calculation result of the seismic attenuation empirical formula. Comparing the peak acceleration values of seven monitoring points data, the result shows that the nuclear power plant building has an amplification effect on seismic acceleration signals, and the amplification coefficient is positively correlated with building elevation. The conclusion of spectral analysis of peak acceleration data shows that predominant frequency points of seismic response data in nuclear power plant buildings are mainly concentrated in the range of 10 to 20 Hz, and seismic acceleration signals in the range of 10 to 20 Hz also have certain destructive effects on the building. This conclusion is inconsistent with the seismic triggering filtering range (1 to 10 Hz) specified in NB/T 20076-2012 seismic instrument criteria, due to the fact that the seismic trigger recognition algorithm of the seismic instrument system is set in a filtering range of 1 to 10 Hz. This defect will reduce the performance of the seismic instrument system’s depth safety defense.

To provide a statistical formula between the shear wave velocity and depth of typical cohesive soil, silt, sandy soil, and gravel soil in Xiangyang area, Hubei Province, based on 102 measured borehole wave velocity data, we use multiple univariate regression models to fit and analyze the relationship between shear wave velocity and depth of common soil layers. Then, we discuss the influence of soil state on the correlation between the two. Finally, we verify the rationality and reliability of the statistical formula using actual drilling data. The results show that: 1) Except for artificial filling, there is a strong correlation between the shear wave velocity and depth of other conventional soil types in Xiangyang area, and the degree of dispersion increases with the increase of depth; 2) As the density or plasticity of the same soil type increases, its average shear wave velocity also increases; 3) Considering the soil state can make the prediction results of the regression model more specific and closer to the true values, but there is uncertainty in the changes in the goodness of fit of the model; 4) Regionality has a significant impact on the statistical relationship between soil shear wave velocity and depth. The shear wave velocity regression models provided in this article for various soil types in the Xiangyang area have better prediction accuracy and error stationarity compared to the national soil type models. They can provide valuable reference basis for seismic disaster risk survey, site soil dynamic properties research, and determination of seismic motion parameters in the Nanxiang basin and surrounding areas.

We conduct PPP experiments using 80 global MGEX stations in September 2021, and compare the results with ZTD product released by the international GNSS service (IGS) as a reference. The results reveal significant advantages in ZTD accuracy of multi-system joint estimation. The average RMSE accuracy of GPS+BDS dual-system is approximately 0.6 mm higher than that of single GPS system, while the GPS+BDS+GLONASS+Galileo four-system exhibits a further improvement of about 0.9 mm than dual-system. The ZTD estimation accuracy of GPS under single-system condition is higher than that of BDS. In terms of spatial distribution, the improvement of ZTD estimation accuracy is more significant with increasing latitude. The four-system PPP ZTD accuracy is better than 5 mm when latitude exceeds 50°. Moreover, elevation increase of observation stations can improve ZTD estimation accuracy while latitude remains unchanged. The ZTD estimation accuracy is significantly improved under ambiguity resolution. The average absolute error (MAE) and root mean square error (RMSE) of ZTD estimated by single GPS system are 7.6 mm and 8.4 mm, respectively, which are about 11% and 12% higher than floating-point solutions. The average convergence time is reduced by 20 minutes.

To obtain high-quality original seismic data of the Wuwei basin of the lower Yangtze block, we conduct experimental research based on the reflection seismic data from 2019 to 2020, such as high density wide line acquisition technology, excitation technology, and tomographic static correction technology. We summarize a set of collection and construction parameters suitable for shale gas seismic exploration in the Wuwei basin, and apply these parameters to the newly deployed seismic exploration work in the research area. We obtained seismic data with high signal-to-noise ratio. By performing Kirchhoff pre-stack time migration on the data, we obtain a high-resolution and high-precision time-domain reflection profile. The target layer(Permian) on the profile has strong reflection wave energy and continuous in-phase axes, which can basically clarify the geological structure framework of the area. This can provide reliable seismic imaging data for the drilling and deployment of shale gas in the Wuwei basin.

The strain observation data of Xuzhou station recorded abnormal phenomena before the M5.5 earthquake in Pingyuan, and the abnormal phenomena continued to return to normal after the M2.6 earthquake occurred in Heze. The timing of the anomaly is highly consistent with the occurrence of two earthquakes. By using precision analysis, difference analysis, minute value anomaly analysis and wavelet analysis, we determine that the abnormal variation of the strain data of Xuzhou platform before and after the earthquake is related to the earthquake.

Aiming at the linear Gaussian state model of integrated navigation system with inaccurate system noise and measurement noise statistics, this paper proposes a modified variational Bayesian adaptive filter(MVBAKF) for integrated navigation system.Firstly, the Wishart distribution is selected as the conjugate priors of Gaussian covariance matrix with known mean value, and the joint probability distribution function of measuring noise variance, state vector and prediction error covariance matrix is given. Then, the formula of measurement noise variance and state vector prediction error covariance matrix is given by using the variable decibels method, and then the MVBAKF algorithm with iterative characteristics is proposed. Finally, the simulation experiment of GNSS/SINS integrated navigation system based on MVBAKF algorithm is carried out. Experimental results show that MVBAKF algorithm can accurately estimate the variance of measurement noise, and can effectively overcome the influence of inaccurate system noise statistics on the filtering accuracy compared with traditional VBAKF algorithm, and thus improve the filtering accuracy of integrated navigation system.

Whether the initial search space is set reasonably or not directly affects the reliability and search efficiency of ambiguity resolution. In view of the constellation characteristics of BDS system, it is necessary to analyze the correlation between ellipsoid volume and the number of candidate points, and the effect of data redundancy for BDS2 and BDS3 under different satellite numbers and frequencies. For the drawback that objective function method is prone to produce too many candidate vectors when determining the ambiguity search space, we propose an optimized search space determination method, and verify the effectiveness of improved method through experiments. The results show that the improved search space determination method significantly reduces the number of actual ambiguity candidate vectors, with average improvement up to 35.02%, and ensures that the number of candidate vectors contained in 94% space satisfies the requirements. The improved search space method improves search efficiency by nearly 33% on average after applying it to different search methods, which is conducive to separating the redundant candidate vectors in initial search space, thus improving the ambiguity search efficiency.

The traditional Kalman filter(KF) of GNSS/SINS integrated navigation system is optimal under the minimum mean square error(MMSE) criterion and under the Gaussian hypothesis. However, when the measurement noise is disturbed by heavy tail pulse noise, the filtering performance of KF is seriously degraded. To solve this problem, we propose a maximum entropy Kalman filter(MCKF) for integrated navigation system. First, we establish the state equation and measurement equation of MCKF. Then, using the principle of maximum entropy, we establish a Kalman filter based on the maximum entropy criterion, and design its filter iteration flow. Finally, we simulate the GNSS/SINS integrated navigation system in the environment of mixed Gaussian noise and heavy tail pulse noise, respectively. The simulation results show that KF performs better than MCKF under mixed Gaussian noise interference, MCKF has better filtering performance than KF under the interference of heavy tail pulse noise, and MCKF is equivalent to KF when the kernel bandwidth tends to infinity.

At present, the seismic stations need to use two sets of acquisition systems to monitor and record weak signals and large seismic signals. To address this problem, this paper proposes a data acquisition method that automatically switches acquisition modes. When monitoring weak signals under normal conditions, the acquisition system uses small-signal channel ADCs for graded sampling, and when large earthquakes and giant earthquakes occur, the system automatically switches to use large-signal channel ADCs for sampling. Experiments show that the dynamic range of the acquisition system reaches 128 dB for single AD data acquisition at 100 Hz sampling, and 158 dB for double AD data acquisition at 100 Hz sampling.The improved data acquisition method effectively improves the dynamic range of seismic signal acquisition, and improves the performance of the data acquisition system to a certain extent without increasing the hardware cost.

Acoustic positioning technology can transfer the position reference frame maintained by GNSS into the ocean. Domestic GNSS-acoustic seabed positioning experiments typically involve the cooperation of multiple hardware devices. However, the observation data outputted by different devices may suffer from time stamp jumps. While time stamp jumps can be resolved through redundant observations, there is currently no effective solution for cases without redundant observations. Therefore, we propose a time stamp jump correction method based on parameter search. By constructing a search space for time stamp deviations and using the unit weight variance of acoustic positioning results as a criterion, the time stamp jump in observation data is searched numerically. The proposed method is validated using measured sea trial data. The results show that the parameter search method successfully detects a time stamp jump of approximately 1 second in acoustic device data and improves the accuracy of acoustic positioning from decimeter-level to millimeter-level by correcting the data time stamps.

Using high resolution remote sensing images, we accurately extract the water body boundary of the head area of the Three Gorges reservoir. A precise discretized numerical model is constructed for the water body to simulate and calculate the gravity effect of the head area of the Three Gorges reservoir at different storage and release water levels. We finely preprocess the continuous observation data of the gPhone 101 gravity gravimeter at Zigui station in 2017 and the gPhone 113 gravity gravimeter at Maoping station in 2019 to 2021. The results show during the water storage process from 145 m to 175 m, the simulation values of gravity change on the bank at different storage levels (distance is 5 m) are 0 to 28 μGal, 0 to 47 μGal, 0 to 60 μGal, 0 to 97 μGal, 0 to 170 μGal, and 0 to 210 μGal, respectively. There is an effect of 10 to 20 μGal within 2 km from the bank at the time when the storage level is elevated by 5 m. When the water storage level increases 30 m, there is an effect of 30 to 40 μGal within 5 km from the bank. The gravity residuals mainly reflect the hydrological gravity effect information, the gravity residuals at Zigui station recorded about 40 μGal of gravity change, and the gravity residuals at Maoping station recorded about 50 μGal of gravity change. The gravity change trend and the water level change show very good consistency, verifying the accuracy of the model simulation results, and provides a reference for the stability monitoring of the head area of the Three Gorges reservoir and its banks.

Based on lithologic characteristics, samples age, sporo-pollen and sedimentary cycle analysis of the controlled drill in northern Taiyuan basin, as well as the known data of sporo-pollen assemblage and strata lithology of late Cenozoic in Taiyuan basin, we divide the Quaternary strata in Taiyuan basin. The Quaternary strata from top to bottom in Taiyuan basin is divided into: from 0 to 31.6 meter is the Holocene; from 31.6 to 95.5 meter is the late Pleistocene, which is further divided into the early(31.6 to 47.8 meter), the middle(47.8 to 78.2 meter) and the late(78.2 to 95.5 meter) periods; from 95.5 to 186.16 meter is the middle Pleistocene; from 186.16 to 250.42 meter is the early Pleistocene. On this basis, we analyze the evolution characteristics of the Quaternary in Taiyuan basin based on the color and particle size features of sediment and sporo-pollen analysis results.

Based on NGA database and using genetic programming techniques, we give a set of prediction equations for PGA, PGV and PGD. On the basis of the explicit prediction formula, the reliability test and model comparison are carried out by establishing the correlation between ground motion parameters and key seismological parameters such as magnitude, fault distance, fault mechanism, and site shear wave velocity within 30 meters. The results show that: 1) Compared with the traditional decay relation-like prediction equations based on nonlinear regression techniques, genetic programming techniques do not need to specify the equation form of the decay relation, can model the complex behaviors of PGA, PGV and PGD, and give explicit formulas to meet engineering needs. 2) Compared with the Campbell-Bozorgnia attenuation relationship, the prediction effect of PGA and PGV based on the genetic programming techniques is slightly better; the RMSE and MAE of the PGD prediction model are 5.47 and 1.64, respectively, which are significantly smaller than those of the Campbell-Bozorgnia model, which are 45.98 and 4.61. 3) The obtained ground motion prediction equations are characterized by magnitude effect, site amplification effect, and saturation effect of near-field large earthquakes, but fail to reflect the soft-soil damping effect, and the maximum site amplification coefficients of PGA, PGV and PGD are about 1.42, 2.53 and 2.64.

We use the catalog of modern earthquakes in the Beijing-Tianjin-Hebei region from 1980 to 2022 as a statistical sample. To grid the study area, we use the incompletely centralized Voronoi segmentation method based on spatial segmentation. Based on the Poisson model, the probability model of earthquake risk is established, and we conduct the probability prediction of small and medium earthquakes at the medium-term scale of the study area. The results show that the calculated probability of relatively high value region has a certain correlation with the occurrence of earthquakes with M_S≥3.0, which can provide a reference for medium and long term earthquake prediction.

Using the three-component teleseismic wave shape data recorded by 85 mobile seismic stations in northwest Yunnan(25.0°N to 26.9°N, 99.20°E to 100.74°E), we extract the P-wave receiving function, and obtain the Moho depth and Poisson’s ratio by H-k scanning method. Then, we apply the receiving function common transformation point(CCP) stacking method, plotting a total of 6 vertical sections NW and NE were plotted. The results show that the crust thickness in the study area varies from 38.5 to 52.4 km, with the crust thickness being thicker in the northwest and thinner in the southeast. Poisson’s ratio varied between 0.24 to 0.34, showing a four-quadrant distribution. The wave velocity ratio decreases with the increase of crustal thickness in the study area, showing a certain negative correlation. Yunlong M5.1, Eryuan M5.5 and Yangbi M6.4 earthquakes all occurred in the high gradient zone of Poisson’s ratio. According to the CCP profile, the Moho in the study area fluctuates significantly in the NW direction, becoming shallower from the north to the south. The uprise amplitude is about 5 to 10 km. The fluctuation of NE toward Moho is relatively smooth, with an average depth of about 42 km. The stratification in the Earth’s crust is complicated, and there are few continuous interfaces. There is a wide negative amplitude band in the middle and upper crust below the Yangbi earthquake, which may provide seismogenic environment for the occurrence of earthquakes. The average depth of the D410 discontinuity plane is about 420 km, the average depth of the D660 discontinuity plane is about 660 km, and the thickness of the mantle transition zone is 210 to 260 km.

We select 38 views of Sentinel-1A SAR images, and obtain the surface subsidence results within 5 km along the Qufu-Heze section of the Lunan high speed railway using SBAS-InSAR technology for the period from February 2019 to November 2022. We analyze the distribution characteristics and patterns, and use the PSO-BP model to predict the subsidence of some feature points. The results show that the annual average deformation rate is between －20 and 15 mm/a, the maximum subsidence velocity is 25.46 mm/a, and the maximum lifting velocity is 17.43 mm/a within 0.1 km along the high speed railway; the RMSE of the subsidence prediction value obtained by the PSO-BP model ranges from 5.8 to 12.4 mm, which can predict the surface subsidence well.

The traditional method of geoid-quasigeoid separation is difficult to meet the accuracy requirements in mountainous regions with complex terrain. We use a strict formula to calculate the geoid-quasigeoid separation in the mount Qomolangma area and analyze spatial changes. The results show that the total correction using the strict formula varies from －3.270 m to －0.119 m, the potential correction reaches 1.272 m, and the gravity gradient correction reaches －0.138 m. The magnitude of these corrections is large enough and needs to be taken into account in mountainous areas. The strict method and the approximate method both have a certain correlation with height, and the former produces smoother results than the latter. Under the influence of Bouguer gravity anomaly and terrain changes, some local features of strict method are negatively correlated with height.