04 May 2017, Volume 37 Issue 5
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jgg. 2017, 37(5): 441-445.
To solve the problem of ill-conditioned normal equation coefficient matrix for big rotation angle’s three-dimensional coordinate transformation model, an improved model is put forward, based on coordinate centralization combined with adaptive scaling. Through analysis of an example, it is verified that the ill-conditioned normal equation coefficient matrix can effectively be improved with the model, with results that are more reliable than the existing model.
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jgg. 2017, 37(5): 446-449.
The paper introduces the definition of ITRF2014, the global distribution of stations, the strategy of processing input data, and the improvements of ITRF2014 relative to ITRF2008.ITRF2014 first applies a non-tidal atmospheric loading model, then enhances the accuracy of the reference framework and optimizes the internal model. On the basis of conventional products, such as station coordinates, speed, residuals and EOPs, ITRF2014 has issued two new products: the geocentric motion model based only on SLR, and the post-seismic parametric model. The improvements on the original model have made advancements in updating and refining the regional coordinates and estimation of earthquakes.
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jgg. 2017, 37(5): 450-456.
We compare and analyze the SCB prediction results of fourteen BDS satellites based on the linear model, the quadratic polynomial model, the grey model (GM (1,1)) and Kalman filtering model, using precise SCB data of BDS to conduct the prediction tests. The SCB prediction performance of the BDS satellites according to corresponding orbit types is discussed and we summarize the characteristics of these models specific to the SCB prediction of BDS.
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jgg. 2017, 37(5): 457-461.
A multipath reduction algorithm based on GPS/BDS measurement is proposed in this paper. With pseudorange and Doppler observations of BDS/BDS, the availability of observations is enhanced. In addition, combined with the robust adaptive Kalman filter, the multipath errors caused by high buildings in urban areas can be efficiently reduced and thus the accuracy and reliability of satellite navigation is improved. Results from a car driving test show that position error is reduced from 4.9 m to 4.3 m with GPS and GPS/BDS point positioning respectively. When the robust filter method is adopted, the position error has been further reduced from 4.3 m to 3.4 m.
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jgg. 2017, 37(5): 462-466.
This paper is concerned with the sidereal day repeat characteristics of the multipath error and high frequency random noise of calculated coordinates for real-time deformation monitoring. First, we apply the EMD and EMD combined with wavelet threshold de-noising methods, to the existing coordinates multipath time series model. Then, based on this model and through sidereal filtering, we weaken the multipath error of subsequent coordinates, which has a strong correlation with the model. The measured data processing results show that the EMD method can remove the high frequency random noise sequence and weaken the effect of multipath error of GPS/BDS real-time monitoring effectively, improving by 50% the accuracy of real-time monitoring. The EMD and wavelet combined method is superior to single EMD filtering method.
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jgg. 2017, 37(5): 467-471.
We assess the orbit quality of BDS GEO and IGSO satellites, based on global navigation satellite system(GNSS) and satellite laser ranging(SLR) observations. When using GNSS observations for BDS orbit determination, the results show that the SLR residuals of C01, C08 and C10 have a certain degree of deviations, and that the values from the satellites are not identical. In combined orbit determination using GNSS and SLR observations, the orbit accuracy with SLR range biases estimated and not estimated are analyzed. The results show that SLR range biases must be estimated for C01 due to a large bias in GNSS-only solution. There is a certain degree of improvement in orbit prediction for C08 and C10, using the combined solution with estimating SLR range, bias or not. In addition, statistics of range biases for C01 is about 50 cm and less than 5 cm for C08 and C10.
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jgg. 2017, 37(5): 472-477.
The application of ground-based GPS PWV inversion has been limited due to the inaccurately calculated the weighted mean temperature because most ground-based GPS fails to detect upper-air meteorological data. This paper analyzes the methods of obtaining the weighted mean temperature by deriving the data from GGOS atmosphere weighted mean temperature grid data in Xinjiang. By using the radiosonde data, this paper evaluates the accuracy of the weighted mean temperature (GTm) derived from GGOS atmosphere weighted mean temperature grid data considering seasonal and geographic variations. We then establish a refined model to correct (GTm). Results show that the (GTm) derived from mean value interpolation after correction using the refined model can meet the requirements of ground-based GPS precision PWV inversion in Xinjiang.
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jgg. 2017, 37(5): 478-481.
ECMWF can provide a wide range of grid on the vertical dimension of water vapor density, temperature, pressure and other profile data, and can also get a wide range of meteorological elements inversion. GPS could get the PWV of one single point, but the accuracy and time resolution can be very high. This article integrates the advantages of two methods of inversion to study a typical frontal rainfall in Taiwan, by detailed analysis of the changed characteristics of the meteorological elements before and after the rain. Results show that the ECMWF inversion can be used to judge whether there are the kinetics conditions for rainfall in a certain period. According to the results of GPS inversion, the forecast could be guided by higher time resolution.
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jgg. 2017, 37(5): 482-486.
Through the study of relaxation parameter, access order, stop rule, non-negativity constraints, as well as the characteristics of water vapor tomography, this paper proposes water vapor tomography constraint ART algorithm (WVTART) based on grouping and sorting. In order to obtain the global solution efficiently and robustly, observation equations should be sorted by the principle of un-correlation. The results verify that the WVTART method can improve the convergence speed and the accuracy of the solution.
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jgg. 2017, 37(5): 487-491.
In this paper a complementary ensemble empirical mode decomposition (CEEMD) de-noising algorithm for MEMS-gyro, is proposed to alleviative the drawbacks of the present empirical mode decomposition (EMD) forced de-noising method. The proposed method readily conditions signal distortion based on intrinsic mode function (IMF), as selected by composite evaluation; the results can be transferred into the linear combination of sample entropy (SE) and similarity. The filtering thresholdings are calculated by the signal noise parameters, and the relevant IMFs are filtered by those thresholdings. Simulation and test results show that the effect improves greatly as compared with the forced algorithm. In particular, the MEMS-gyro’s bias instability decreases by 76.4%, the MEMS-gyro’s rate ramp decreases by 62.3% and the MEMS-gyro’s RMSE decreases by 67.5%, after filtering by the proposed method. Furthermore, the filter improves the positioning accuracy of MEMS-IMU pedestrian navigation.
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Evolution of P Wave Velocity Structure before and after the Xinyuan-Hejing MS 6.6 Earthquake in 2012jgg. 2017, 37(5): 492-496.
Based on the phase observation report from Xinjiang regional seismic network, we use the finite difference tomography method to invert the P-wave velocity structure of the central and eastern segments of Xinjiang Tianshan mountain. We then acquire the half-annual scale for the evolution of P wave velocity structure before and after the Xinyuan-Hejing earthquake. The results show that the zone of high P-wave velocity difference is produced before the earthquake in the epicenter and the surrounding area at a depth of 12 km, with an anomaly amplitude up to 0.3 km/s. The apparent difference in speed reflects changes of the crust medium by half-annual scale of different time in the same depth of P-wave velocity differential analysis.
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jgg. 2017, 37(5): 497-501.
In order to analyze deformation trends, we use the four-period reiteration precision level data of the capital circle to calculate the ground vertical deformation rate for 2001-2005, 2005-2007 and 2007-2014, draw the vertical deformation rate map and the profile map, combining these with the main fracture distribution and activity. The results show that the deformation characteristics mainly give priority to trend movement in the first two periods, presenting ‘east and west to up, north and south to down’, while the latest data show that deformation appears trend turning in both east and west, with an especially sharp sinking in the Zhangjiakou-Bohai tectonic belt. We predict a tendency of strengthening stress field for this area.
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jgg. 2017, 37(5): 502-506.
We collect and calculate the GPS continuous station data, regional station data and leveling data of the Jiangsu area between 2011 and 2015. The characteristics of horizontal deformation in this area are researched by using the time series of GPS baseline and the strain rates. The fitting method considering annual and semi-annual periods is adopted to calculate the velocity of the Maoshan fault vertical deformation. We analyze the vertical deformation of this area. The results show that Jiangsu is controlled by the stress field extrusion of the crust and that the main strain direction in most areas is east-west. The Jiangsu section of the Tanlu fault zone is located in the north-south gradient with tension and extrusion. The vertical velocity of this area is normal. The horizontal and vertical results show that Maoshan fault is the tension fault.
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jgg. 2017, 37(5): 507-510.
In this paper, the subsidence of Tangshan mine during the period from December 2012 to February 2014 is monitored with PSI technique using thirteen high resolution TerraSAR-X acquisitions. The overall deformation analysis is carried out on coherent targets with strong intensity stability and high spectral coherence, which are extracted from 47 interferograms with short temporal and spatial baselines, to obtain the subsidence velocity and time-series. The monitoring results show that there are two subsidence centers separately in the northeast and west directions, with a maximum subsidence velocity 58.2 mm/a. It is also found that ground rebound took place from June 2013 to September 2013, yet ground subsidence is approximately linear in the other observation period. Finally, by comparing two elevation error histograms before and after correction, we conclude that the two times regression method used in this paper is perfectly effective for the reduction of topographic residual errors.
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jgg. 2017, 37(5): 511-515.
In this paper, a method for predicting the deformation of rock surrounding a tunnel is put forward based on the weighted composite quantile autoregressive model, giving the principle and algorithm of the method. Using a case study of Yangzong tunnel in Kunming, the weighted composite quantile autoregressive prediction model is calculated and compared with other models. The results show that the forecast effect is better than that of the AR(2) model of the non-weighted composite quantile estimation, the auto regression prediction based on least square parameter estimation, the support vector machine optimized by genetic algorithm and some other prediction methods.
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jgg. 2017, 37(5): 516-520.
In this paper, the range, angle, spot and registration error are analyzed, and the point cloud error ellipsoid model is given. According to the relationship between the error ellipsoid half shaft and limit value of point error, the deformation monitorable indicator is deduced. The proposed method is verified according to the simulated landslide.
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jgg. 2017, 37(5): 521-526.
A phenomenon of “frequency hopping” occurs when processing non-stationary seismic signals by wavelet packet. The existing method of decomposing seismic signals in high level based on wavelet packet cannot rapidly obtain the arrangement rule of frequency band numbers and node numbers. To rectify this disadvantage, a fast algorithm for converting frequency band to node numbers is proposed, based on wavelet packet transform and XOR algorithm. For analysis, we use the MATLAB platform, take Tangshan (north-south) seismic wave as an example and set the corresponding procedures. Our results get the same arrangement rule as the existing method from frequency band numbers to node numbers, verifying the correctness of the proposed conversion algorithm.
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jgg. 2017, 37(5): 526-530.
In this paper, the situation of different operation states of Tai’an PET gravimeter is introduced, and the anomaly of the grid is judged by comparison with the very wide band digital seismograph. At the same time, the main interference factors of the observation data are eliminated, and the relative objective gravity observation trend information is extracted. It is found that there is a negative trend drift of the gravity meter in Tai’an seismic station from 2013-09~12 and 2014-02~04.
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jgg. 2017, 37(5): 531-535.
Based on the data from a typical drilling profile in Hankou and the results of a dynamic triaxial test, the equivalent linear method is used to describe the nonlinear characteristics of soil layers. An one-dimensional wave method is used in soil seismic response. Then, the possibilities of liquefaction for the soil layers within the depth ranging from 10 to 36 m, under different intensities of earthquakes, are analyzed. The results show that: 1) liquefaction is still possible for the sand layers with a depth more than 20 m when the intensity of earthquake is above Ⅶ or Ⅷ degrees; 2) the possibility of soil liquefaction decreases as the depth increases; 3) the spectral characteristics and stationary duration of the inputted ground motion are possible factors that may affect the results of liquefaction. We suggest the method in this paper can provide reference for liquefaction evaluation in deep soil layers.
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jgg. 2017, 37(5): 536-540.
Using the continuous and uniform micro-tremor test, data are collected in Chengxian. We analyze the spectrum characteristics of micro-tremor test data using a single point of spectrum ratio method, then the recommended value of the site predominant period is obtained according to the classification of the spectrum type results. Based on existing drilling data, the correlation between site predominant period and the thickness of the overlay is established. Using the actual engineering data to verify the accuracy and the universality of the relationship. Due to its economy, simplicity and speed, the micro-tremor test provides basic data for the seismic safety evaluation of region engineering sites, earthquake seismic micro-zoning, the categories of site classification, site selection and evaluation.
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jgg. 2017, 37(5): 541-545.
The results of simulation experiments show that SSA can separate and extract the periodic signal and trends, effectively reduce noise of which the standard deviation is lower than the signal amplitude, and detect singular points in signals. Through applying SSA to data processing of earth tilt and strain in Dandong, Xuzhou and Jingxian stations, the results indicate that SSA can extract components of long trends of the data, separate tidal waves effectively, and identify the rain interference components of which the periodic signal is about 7 to 15 days. These results have some reference implications for disturbing rejection and extracting exception. Finally, after significant data validation, we summarize choice of the experience embedding dimension when SSA is used for tilt and strain data.
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jgg. 2017, 37(5): 546-550.
This paper introduces the design and implementation of system architecture, service architecture, database and system functions on earthquake industry user oriented seismic data sharing service platform. This platform provides an effective, convenient, sustainable, highly scalable and visual data sharing service by interactive portal. Based on national scientific data sharing project requirements, a platform that provides standard data searching, data visualization, and data sharing for users can beneficially facilitate the exchange and sharing of seismic data.
