The shallow seismic reflection method is used in the geophysical exploration of the Danjiang fault in the southern Qinling mountains tectonic belt. Through data processing and analysis, high resolution shallow seismic profiles with characteristics of geometric distribution, breakpoint burying depth and fault properties are obtained. In this paper, the results of seismic profiles and drilling data of part lines are verified by comparison. The results show that the shallow seismic reflection is effective for the hidden detection in this area, and this method can provide reference for the detection of buried active faults.

This paper is based on 3D seismic data. According to the principle of division of structural belts, we classify the tectonic belt into three categories: the fault, salt structure, and buried hill, in total 25. This paper selects a typical tectonic belt in these three categories for discussion.

This paper considers the lithosphere magnetic field of eastern-Dabie area (115~117.5°E,29.5~32.5°N). Through analysis and inversion, we get geomagnetic structure models of underground media, such as the shallow model of lithosphere geomagnetic field, deep model of lithosphere geomagnetic field and the depth distribution model of Curie interface. By analyzing features of distribution of some related magnetic anomalies, we discover that the positive anomaly magnetic field of lithosphere in eastern-Dabie area is in the structural unit of Jianghuai promontory, Tancheng-Lujiang fault zone and the depression of lower Yangtze platform; a huge EW trend geomagnetic negative anomaly passes through the northern Huaiyang fold belt. Comparing the magnetic field of lithosphere and the shallow model of lithosphere, we are able to discover some trends of hidden fault and depth of cut. The deep model of lithosphere magnetic field, to some extent, reflects the distribution and structure of the lithosphere basement in this area. Furthermore, the depth of Curie interface could reveal the distribution of magma activities in this area.

In order to study the location and the spatial distribution of buried faults and the crustal shallow structure in the eastern part of Wuzhong area in Ningxia, we lay several high resolution shallow seismic reflection lines where the Chongxing fault may exist. The results show that the Chongxing fault is a NNE-trending normal fault. The interpretation of shallow reflection seismic sections shows that the fault extends about 12 km in length and has a steeper, nearly upright, dip angle. The breakpoint FP1 on the southern WJQ line reveals that the Quaternary bottom interface TQ is broken by the Chongxing fault, while the breakpoint FP5 on the northern SJDD line and the breakpoint FP6 on the WJZ line reveal that the fault intrudes upwards to the Quaternary internal interface T02, which seems to reflect that the fault activity is relatively strong in the northern section and relatively weak in the southern section.

Based on reliability theory, a reliability analysis method for bedding rock slope is established, considering the effect of blasting load. The calculation expressions of the reliable index and failure probability are obtained. Taking a high-cutting slope as an example, the steady state and failure probability  are analyzed, and the change rules of failure probability are discussed under diverse cohesion, internal friction angle, explosive charge and distance to burst center. The calculated results show that cohesion has a great influence on failure probability, and that failure probability decreases linearly with the increase of internal friction angle. When the single-hole dose increases from 10 kg to 160 kg, the failure probability increases to 97.10%. When the distance to burst center is less than 20 m, the failure probability decreases rapidly, but the decreases reduce while distance exceeds 20 m. Finally, considering the timeliness of blasting vibration, it is found that blasting load makes the failure probability increase 49.61%, and the impact time of single blasting vibration is about 6 seconds.

We solve the problem of low efficiency and heavy workload in the selection of traditional GNSS carrier phase combination observations. On the basis of error analysis of the wavelength standard, ionospheric delay standard and observation noise standard of the BDS triple-frequency carrier phase combination observations, with long wavelength, weak ionosphere and weak observation noise standard as the clustering indexes, the fuzzy C-means clustering algorithm is used to optimize the data of the BDS triple-frequency carrier phase combination observations. Then, through the matrix transformation method and measured data, the integer ambiguity of the optimized combination is resolved, and the variance-covariance matrix of the combination ambiguity and the ambiguity difference between each epoch is analyzed, proving the feasibility and reliability of the method.

Three BD-2 satellites in different orbits are analyzed in this paper. Based on the clock bias of two-way satellite-ground time comparison by wireless radio in some periods, the frequency accuracy, stability and drift of their primary atomic clocks are calculated. The results indicate that their frequency accuracy, stability and drift are respectively better than 1011,1013 and 1014, respectively. In addition, for the GEO-1 satellite, the performance of atomic clock meets the design requirements and is still healthy enough to not influence the service quality of the BD-2, even as it is about to reach its projected lifespan.

The atmospheric water vapor conversion factor K is an important parameter in the progress of retrieving precipitable water vapor(PWV) from the zenith wet delay(ZWD) of the GPS. In this paper, four years of atmospheric water vapor conversion factor K values are calculated using radiosonde profiles derived from 19 radiosonde stations distributed in southwest China. The Emardson model is refined using K values from 2011 to 2013; finally, two refined K factor models are developed: the Emardson-I model(elevation independent) and the Emardson-H model(elevation dependent). These two new models are validated using 2014 K values. The results are:(1) Emardson-H model yields more accurate and stable results than Emardson-I model for predicting the K factor; (2) the performance of the Emardson-H model is significantly better than the Emardson-I model in high-altitude areas, indicating that elevation is an important factor for the K value calculation in these areas. In addition, the two new models are used for retrieving GPS-PWV at Lhasa station, with results showing that the Emardson-H model has excellent performance in retrieving GPS-PWV, and both models can achieve GPS-PWV retrieval precision of better than 2 mm.

We propose a method of simultaneous ambiguity resolution based on multi-antenna network for single epoch, applying the following steps. Firstly, wide lane ambiguities from each baseline with length constraints are resolved synchronously, and the approximate baseline vector of the dm~cm level precision is obtained. Then, the basic frequency ambiguities of each baseline are resolved with the wide-lane baseline components constraints, and the mm level baseline components are derived. The key of this approach is to verify that wide lane ambiguities are correct, namely, the priori information for resolving the basic frequency ambiguities is accurate. Owing to few observations for one epoch, the tested ambiguity using only ratio is not reliable. A comprehensive judging criterion combining baseline error, mean square error of weight unit, the closed loop of baseline network, and ratio value is proposed; this can avoid accepting the wrong ambiguity and rejecting the correct ambiguity. The successful rate of ambiguity resolution using the above-mentioned algorithm is increased by 1%~2%. More navigational information for the mobile platform can be obtained and its service ability can be improved.

Based on the geometrical layout of satellite constellation, a three-dimensional convex hull satellites selection algorithm for multi-GNSS precise point positioning is constructed. In order to further improve the positioning performance of multi-GNSS PPP, we propose the idea of three-dimensional convex hull satellites selection algorithm considering the quality of observations. Finally, the selection effect and positioning performance of the proposed algorithms are verified and analyzed by employing the measured data.

In order to explore the influence of antenna tilt attitude on multipath delay of satellite signals, the relative position between satellites and tilt antenna is established. According to the comprehensive index of multipath effect, theoretical analysis and experimental verification are carried out. The results show that when the antenna attitude is tilted, the multipath effect obviously increases, the number of effective observations decreases, and positioning accuracy deteriorates. The multipath delay is related to the tilt direction and angle of the antenna and the multipath of satellite signals in different azimuths and altitudes. Delays have different patterns of variation.

This paper analyzes the observation quality of the low-cost single-frequency u-blox receiver and evaluates its attitude determination precision by experimental comparison. The results, based on real data, show that the SNR of GPS, BDS observations collected by u-blox is slightly lower than a surveying receiver; pseudorange accuracies of GPS, BDS observations are 0.91 m, 0.56 m, phase accuracies are 1.13 cm, 1.20 cm, respectively. The orientation precision of the u-blox receiver can reach 0.2°/m and 0.4°/m of heading and pitch in a static environment, while in a dynamic environment it can reach 0.3°/m and 0.6°/m, which is slightly worse than that of the single-frequency resolution of high-cost surveying receiver.

Based on the geometrical layout of satellite constellation, a three-dimensional convex hull satellites selection algorithm for multi-GNSS precise point positioning is constructed. In order to further improve the positioning performance of multi-GNSS PPP, we propose the idea of three-dimensional convex hull satellites selection algorithm considering the quality of observations. Finally, the selection effect and positioning performance of the proposed algorithms are verified and analyzed by employing the measured data.

Applying the method of harmonic wave amplitude ratio, we calculate the minute-value data derived from Heilongjiang Tonghe geomagnetic station.The results show that before the January 2, 2016 MB6.4 deep source earthquake in Linkou of Heilongjiang province, the harmonic wave amplitude ratio of Tonghe geomagnetic station, about 150 km from the epicenter, presents obvious abnormality. There are four anomaly characteristics: (1) the abnormal change of the harmonic wave amplitude ratio YZHx  in the north-south and YZHy in the east-west show the characteristics the form of "down-turning-recovery"; (2) The transition features have the characteristics of migration from deep (long period) to shallow (shorter period) in the abnormal change of harmonic wave amplitude ratio; (3) from March 2014 to January 2016, dielectric properties of the harmonic wave amplitude ratio YZHy  data in Tonghe geomagnetic station have a different abnormality at different depths; (4) abnormal amplitude of the harmonic wave amplitude ratio YZHy  in Tonghe geomagnetic station is greater than YZHx. The reason for abnormal characteristics is that the western Pacific plate dived under the Eurasian continent at a high speed with a small dip before the MB6.4 deep source earthquake in Linkou. The stress change of the seismogenic body led to electrical properties of the local medium changing near the Tonghe geomagnetic station.

A MS6.4 earthquake struck Ning’er county of Pu’er city in Yunnan, China on June 3, 2007. In this paper, we extract the coseismic deformation field by two-pass differential interferometric SAR(D-InSAR) technology from ALOS PALSAR data. Based on the Okada half-space elastic model, the fault geometry of such earthquake and the corresponding fault slip distribution parameters are then calculated, as well as the changes of Coulomb stress around the fault after the earthquake. The results show that the maximum deformation occurred in the west wall of the fault, with a 51.6 cm deformation in the line-of-sight direction. And the epicenter of the inversion is located in 23.05°N, 101.02°E, of which the focal depth is 3 km, the strike is 145°, the dip is 49.5° and the rake is 153°. We infer that the NNW direction of Pu’er fault is a causative fault, where the main motion characteristics are right-lateral strike-slip, with thrusting component, of which the maximum value of slippage is 1.2 m, and the inversion magnitude is MW6.19. According to the Coulomb stress field, we find that the Mohei fault is located in the area of increasing Coulomb stress, while Jinggu earthquake is located in the area of negative Coulomb stress. In addition, considering both the field investigation data and experimental results, as a shallow earthquake, there is no rupture zone on the surface of Ning’er earthquake.

Velocity estimation by inversion of real seismic data has its intrinsic defect such as acquisition geometry, low signal to noise ratio. In this paper, we discuss the simultaneous joint inversion of seismic and gravity data, which minimizes the combination of single-domain objective functions, in order to reduce the non-uniqueness of inversion and improve the accuracy of seismic velocity. To solve the limitation of petrophysical approach, geological structural constraint which expressed by cross-gradient was adopted to complement the empirical relation between velocity and density. The area under analysis is in south Taiwan strait. The identification of consistent refraction patterns becomes extremely difficult due to the presence of volcanic intrusions and high noise level. Consequently, conventional first arrival tomography can only give a poorly defined velocity model for the basement. The shipborne gravity data along this profile provides a key indicator of the sediment. We fit simultaneously both gravity and seismic datasets by finding the best velocity and density models, subject to two sets of constrains. As illustrated by the presented case, compared to using seismic data only, joint inversion could improve the velocity model, reduce the uncertainty of inversion and thus enhance the resolution of tomography.

We studied the method of computing the horizontal tectonic stress field by the earth gravity field, and then the horizontal tectonic stress field in western Sichuan is computed with the EGM2008. The results show that we can quickly obtain the tectonic stress field using gravity field data. The horizontal tectonic of the Longmenshan and Xianshuihe-Anninghe fault zones is greater, and the accumulation degree is higher than any other area, which reflects that tectonic movement is more active in these areas. The horizontal tectonic stress from the Bayanhar block to the southern China block to the Sichuan-Yunnan block shows clockwise rotation. In the Bayanhar block and southern China block boundary, the strong stop of Sichuan basin in the south China block results in the formation of Longmenshan foreland thrust zone. The tectonic stress field gradually decreases with the increase of depth, and the frequency of seismic activity decreases accordingly. The tectonic stress field is densely distributed with active tectonic activity and frequent seismic activity, which indicates that there is a corresponding relationship between seismic activity and tectonic stress accumulation.

The forward modeling formulae for third-order gradient tensor of gravitational potential caused by the right rectangular prism is derived in this paper. Then, two different approaches are utilized to verify the obtained analytic expressions. One is the comparison between calculating results by our proposed formulae and by the central difference of second-order gradient tensor of the gravitational potential. The other is whether the computing results of the theoretic model meet the Laplace equation.

This article summarizes the history of mobile gravimetry network construction in Yunnan. The grid space and spatial resolution of the gravimetry network in Yunnan and its adjacent areas are calculated according to the principle of fractal geometry. The results show that the optimum grid spacing is 69 km and spatial resolution is 61 km. According to gravity observations in recent years, we prepare a series of images of gravity field changes. The gravity changes for Ludian M6.5 earthquake on August 3, 2014, Jinggu M6.6 earthquake on October 7, 2014, and some earthquakes with magnitude larger than 5 in Dali-Baoshan region, are analyzed. In conclusion, the gravity changes for earthquakes with magnitude greater than 5 can be identified by mobile gravimetry in Yunnan and its adjacent areas, and the network should be improved in the future.

With increasingly higher precision requirements for workpiece manufacturing and assembly, measurement accuracy of instruments also need to be improved accordingly. In order to increase the measurement accuracy of laser trackers, which are characterized by high repeatability, a method of calibration based on length standard device is proposed. By establishing the function and stochastic models of the laser tracker and the laser interferometer observation in the process of the calibration, the correction value and the adjusted value of the observation for the calibration points are obtained according to the least squares principle. With interpolation on the correction value and adjusted value of the observation for the calibration points, we determine the correction value of observations for the practical points, and finally achieve the error compensation for the laser tracker. Horizontal direction calibration and accuracy testing are carried out for the Leica AT401 laser tracker with the length standard device, and the distances measured by laser tracker are compared with those measured by laser interferometer. After error compensation, the RMS of the distance differences is changed from 195 μm to 10.2 μm, verifying the feasibility of this method.