18 June 2013, Volume 33 Issue 3
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jgg. 2013, 33(3): 1-4.
Seismic tomography is used for processing the data of temporary seismostations networks in Tangshan region, and the velocity images of upper and mid crust in this earthquake region are obtained. The results show that, in the upper crust image, the velocity of two sides between the Tangshan fault zone are different，where the northwest side is high velocity zone while the southeast side is low and the Tangshan fault is
belt with sharp velocity variety. Besides in the mid crust velocity image, it shows that there is low velocity belt
near EW strike in the centre of the studied area, and its location and strike are corresponding with the FengtaiYejituo fault which is near EW strike and in Tangshan epicenter region, along both of the depth and horizon, sharp velocity variety in crust exsits too. -
jgg. 2013, 33(3): 5-10.
Based on the newly obtained GPS data and the “block loading” FEA method, the crustal movement of Shanxi rift zone within two time span (1999—2007, 2007—2009) , which before and after the Wenchuan earthquake are simulated, respectively. The results show that the stress and strain fields assume opproximately unifrom NWSE extension before the earthquake. However, after the earthquake they are featured with remarkable compression accompanied with notable extension in the south region. Compared with 1999—2007, in 2007—2009 the maximum principal compressive and tensile stress increases 5-6 times and about 2 times,respectively, and from the north region to the south region of Shanxi rift zone, the direcion of the principal compressive stress changes from NW to NEE. Such stress and strain variation is verified by timeseries of acrossfault short level survey, long distance level survey and baseline of GPS continuous site. It indicates that the compressive and strikeslip displacement between Erdos block and North China Plain block increased after the Wenchuan earthquake. As a result, the crustal deformation and tectonic stress field of the Shanxi rift zone,which located in the boundary of the two blocks, change distinctly.
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jgg. 2013, 33(3): 11-15.
Based on the high precision GPS monitoring data from 2006 to 2010 of China Crustal Movement Observation Network, the present crustal threedimensional velocity fields of Datong basin are obtained. Mainwhile by making use of strain analysis of graphical elements combined with significant test method, the present crustal strain parameters and its distribution features are also obtained, then the tectonic origin of ground fissures in Datong is analyzed. The results show that the present crustal movement of Datong basin demonstrates an overall horizontal extension and internal rift subsidence. The interior basin demonstrates overall tensile strain with the NW-SE direction, the most significant strain is at the northwest of the basin, with its value reaching 1.9×10-6/a, and this area is also the typical crack of Datong basin. The ground fissures in Datong basin is controlled by fault activities under the regional tensional stress field with the NW-SN direction.
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jgg. 2013, 33(3): 16-20.
Based on the GPS regional station observations from 1999—2011 in the Tibet and Qinghai areas, using Euler model, multikernel function method and the spherical strain model, the regional NoNetRotation frame motion field and strains are calculated in the central and southern QinghaiTibet Plateau, and compares and analyses the results before and after the Wenchuan earthquake. The results show: The general movement features of the study area did not change greatly over the years. The crust motion is generally the EastWest tensive movement on the whole. In the central area, the crust motion is primarily the NorthSouth compressive movement, and disparts from south to north gradually. The north movement is mainly concentrated in the central Himalaya block and Lhasa block, and obviously weakened in the north Lhasa block. While in boundary of the Lhasa block and Qiangtang block, the motion changes obviously as the EastWest movement. The eastward motion is strengthened in the study area after the Wenchuan earthquake.
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jgg. 2013, 33(3): 21-24.
The characteristics of crustal deformation and strain allocation in Fujian region are studied with continuous observation GPS data. The results of principal strain rate show that the direction of the principal extrusion deformation is NW in the coastal areas, and strain rate values is the largest in the southeast coastal area of Fujian,the strain rate values decreased gradually from the coastal areas to inland areas, at the same time, its direction deflected gradually. Meanwhile, deformation in two sides of the ZhengheHaifeng fault is obviously different. On its west side the direction of the principal extrusion deformation is NW, while on the east side of the southeast coastal areas ( south of 26 ° N ), the direction is NWEW, and in the northeast coastal area ( north of 26 ° N ), the direction is NWNS. On the other hand, there is a distinct shear deformation near the fault. The movement characteristics of some GPS stations in coastal area of Fjuian show that shear deformation is obvious in the region.
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jgg. 2013, 33(3): 25-29.
The EOF method was used to extract coseismic gravity signals from GRACE monthly gravity field data. Because the GRACE satellites can't sensor the gravity changes due to vertical displacement of the Earth's surface, the gravity disturbance is used as the target signal. First, the temporal gravity disturbances at the grid points, with 0.5° resolution, on the Earth’s surface were calculated according to the GRACE monthly gravity field results, in which the 300 km fanfilter was used. And then the EOF method was applied to these temporal gravity disturbances to obtain the coseismic signals. The results show that the coseismic signals due to the recent 3 huge earthquakes, i.e. occurred in Sumatra, Chile and Japan, were successfully extracted, whereas the coseismic signals due to the Wenchuan earthquake, with relatively smaller magnitude, was not extracted because the signals are inundated by other signals and the error of GRACE data. In order to obtain the knowledge of how large an earthquake whose coseismic signal can be extracted from GRACE data should be, a simulation study was carried out by adding a known signal which was calculated in terms of the focal parameters of the Wenchuan earthquake according to dislocation theory, but with different magnitude. The simulation shows that the coseismic signal can be extracted when the magnitude reaches to Mw8.8 or larger; it is difficult to be extracted when the magnitude is smaller than
Mw8.6; and it is possible to be extracted when the magnitude is between Mw8.6 and Mw8.8. -
jgg. 2013, 33(3): 30-33.
Using the technology of ionospheric tomography, threedimensional ionospheric electronic density maps from April 1st to 15th in 2012 were reconstructed near the epicenter of Sumatra, The electron density anomaly detection is based on the doubled standard deviation. After excluding the solar activity and geomagnetic disturbance, the abnormal ionospheric electron density happened at the UT 10:00 on 11th, UT 6:00 on 13th, UT 6:0014:00 on 14th, UT 14:0016：00 on 15th, and they distributed mainly near the epicenter. The anomalies are likely a premise of the Sumatra earthquake in April.
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jgg. 2013, 33(3): 34-40.
We present a joint inversion analysis of the GPSderived radial (vertical) deformation and GRACEderived gravity rates in North America to examine whether the icesheet models (ICE5G and ICE3G) can fit the satellite based observations. The results show that the existing icesheet models can not correctly predict the concentration of gravity change observed by GRACE in two areas of west and southeast of Hudson Bay. Tests of modifying ICE5G show that a reduction of ice thickness by about 20% in the west area of Hudson Bay and an increase by about 40% in the southeast are required to fit both observed vertical deformation and gravity changes by GPS and GRACE.The results of joint inversion demonstrate that the estimated effective lithosphere thickness (150 km, under a statistical confidence level of 80%) is apparently larger than that valuation (chouq 90 km) inferred from relative sealevel data, while the upperand lowermantle viscosity estimates (3.7 × 1020 Pa s; 1.9 × 1021 Pas; 90% confidence level) are about 20% smaller than those derived from sealevel indicators.
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jgg. 2013, 33(3): 41-43.
The highfrequency signal was often used by groundbased radar as a communication signal, but it was susceptible to atmospheric effects. An environmental correction of radar signal was required to obtain the monitoring accuracy of better than millimeter in precision deformation monitoring using groundbased radar interferometry. A correction method based on the discrete stable point in the whole environment was proposed. The experiment proved that this method can optimize the measurement results for the smallscale scene.
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jgg. 2013, 33(3): 44-47.
Using the theoretical relationship satisfied by atmospheric parameters between two points in the ray path, the influence of the atmosphere layer to astronomical atmospheric refraction was obtained. It not only considered the contribution of electronic displacement polarization of the dry air to astronomical atmospheric refraction, but also considered contribution of electronic displacement polarization and dipole steering polarization of water vapor. The integral representation is given, it does not depend on atmospheric distribution models, and it could adapte the calculation of different directions and meet the demand for highprecision.
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jgg. 2013, 33(3): 48-51.
On the basis of the theory of SVM, different parameter optimization methods of SVM modeling were discussed. Through three practical schemes of GPS height conversion, the characteristics and applied effects on SVM with the different parameter optimization methods were analyzed by the targets of optimization time and conversion accuracy.
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jgg. 2013, 33(3): 52-55.
Curve surface fitting methods have been extensively utilized for the task of conversion GPS elevation to normal elevation. However, errors of the coordinates of GPS observations maybe propagate into the transformed normal elevation during estimating the curve surface parameters. To analyze the influence of these errors in the observation data on the transformed elevation, we employed three models: the quadratic polynomial curve surface, cubic polynomial curve surface and moving quadratic curve surface, to study the accuracy of the converted normal elevation. LeastSquares and two algorithms: Total LeastSquares and Weighted Total LeastSquares to estimate the parameters of these curve surfaces. The results from numerical experiments confirm that the accuracy of normal elevation have been considerably improved when errors of the coordinates of GPS observations data were modeled during the process of transformation.
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jgg. 2013, 33(3): 56-58.
The effect of aging factors on displacement was studied on the basis of the survival regression model. Firstly, the numerical sequence of displacement data obtained by the original monitoring data were transformed to the “event status” sets {s(p)i|0, 1}. Secondly, the aging factors were divided into “months”, “quarters” and “years” , respectively. Finally, the “event status” sets are substituted into the survival regression model, and the effect on the displacement data was researched. The results show that the calculation results are slightly different with the different aging factors when calculating their effect on the displacement.
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jgg. 2013, 33(3): 59-63.
In order to solve the problem that the InSAR atmospheric correction is limited by the number of SAR image and weather conditions, a new tropospheric delay estimation method is proposed, which is based on the terrain and meteorological elements. The zenith tropospheric delay model is constructed and the zenith tropospheric delay is estimated by taking the GPS network in Beijing as an example. The result shows that the precision of the model is similar to the GPS tropospheric delay, which is amounted to mm, and can meet the requirements of InSAR atmospheric correction.
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jgg. 2013, 33(3): 64-67.
The block matrix is obtained by the detailed decomposition of vectormatrix that consists of exceptional conjugate points. The mathematical model of exceptional conjugate points detection is derived; the condition and minimum of exceptional points detection are given through the decomposed block matrix. The case study demonstrates that it is feasible to calculate the registration parameters after detecting and eliminating the exceptional conjugate points through this method, and it will be helpful to improve the accuracy of points cloud registration.
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jgg. 2013, 33(3): 68-71.
To compare the performance of the three slope correction methods(the direct method, the indirect method and the relocation method), ERS1 data over the Vostok region in the Antarctic are processed based on the RAMP DEM model. The results show that the relocation method performs better than the other two methods. The accuracy of the direct method is the worst in the three methods.
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jgg. 2013, 33(3): 72-78.
〗The meteorological data are obtained by pressure interpolation for the estimation of GPS precipitable water vapor (PWV) due to the lack of meteorological parameters at GPS sites. The pressure interpolation formula based on segmented height difference is derived by analyzing the relationship between the interpolated pressure at the GPS sites and the pressure at the nearby radiosonde (RS) stations, and the relationship between the interpolated pressure of the GPS sites and the height difference between the IGS stations and the nearby radiosonde stations using the standard atmosphere (SA) model. The new pressure interpolation formula has the same accuracy as the SA model, and the former is simple when the height difference is less than 100 m. GPS PWV is derived from the new pressure interpolation formula, Saastamoinen zenith hydrostatic delay (ZHD) model and the local weighted mean temperature of the atmosphere (Tm). By comparing with RS PWV, the results show that the new pressure interpolation model can be used to calculate GPS PWV with no meteorological data at GPS stations which the RMS error between GPS PWV obtained from the pressure interpolation formula based on segmented height difference and RS PWV is 13 mm.
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jgg. 2013, 33(3): 79-82.
In order to reestablish the initial value for GM (1,1) model, we proposed a new approach to improve prediction accuracy of GM(1,1) model through optimization of the initial value, which is comprised of the first and the nth vector as the initialization, and derived from a method of least error summation of square. Then we discussed the parameter which affects the fitting results. By contrasting the improved one to the GM(1,1) about the simulation and prediction, we can conclude that the improved one is superior in prediction and simulation, and it is proved that the optimum one widen its suitable range.
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jgg. 2013, 33(3): 83-86.
Highperformance Beidou2/GPS receiver is used to acquire Beidou2 and GPS data at the end of 2011. Then, the navigation and positioning features are analyzed under different movement modes, different regions and different satellite navigation systems. The results show that the separate Beidou2 navigation system can meet the demand of standard positioning in China and surrounding seas.
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jgg. 2013, 33(3): 87-91.
According to the problems in the landslides monitoring using InSAR technique in practical applications, the research was carried out to monitor the landslides based on InSAR technique and multisource observations data. It monitored the landslides comprehensively using highresolution PALSAR data and multisource observations data on the basis of the method of radar interferometry. The landslides in Shijiaying which located in Fangshan region of Beijing were selected as the test area. Then it selected 7 PALSAR images during 2008 to 2010 to build 4 InSAR pairs. The monitoring precision can be achieved to 1 cm. The result proved that InSAR technique combined multisource observations data is a powerful and effective tool to measure surface deformation and study landslides.
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jgg. 2013, 33(3): 92-92-96.
According to the value of the classification and coding of geographic features in these aspects, such as organization of geographic information, data conversion, etc., a strategy was brought forward which could construct fundamental geographic database. In accordance with the principle of the present geographic feature classification, feature datasets were built in the major categories, and feature classes were built in the middle categories with geodatabase. On this basis, the mapping mechanism was established between feature classification code and feature class, and it was used to develop the DLG data software. Through the seamless integration between ArcGIS engine and ObjectArx, this software embedding in the process of AutoCAD was realized, and it can realize the warehousing of DLG data automatically and efficiently.
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jgg. 2013, 33(3): 97-101.
Tightly coupled INS/GNSS based on Robust Extended Kalman Filter algorithm is researched aiming at the observation outliers of GNSS in the INS/GNSS integrated navigation. Firstly, the INS error equations resolved into the Local Lever Frame as well as the INS/GNSS tightly coupled measurement equations are given. Secondly, the resolved model based on leastsquare algorithm is constructed according to the measurement equations and the equal weight covariance is constructed by the least square residual statistic, then calculation steps are given. Finally, measured data are processed to verify the algorithm. Results show that: when the outliers exist in GNSS observations, the tightly coupled INS/GNSS integration based on Robust Extended Kalman Filter can weaken the impact of the observation outliers effectively, and can improve the precision of integrated navigation system.
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jgg. 2013, 33(3): 102-105.
We analyze the correlation between GLONASS IFDB and receiver types and predict GLONASS IFDB based on derived model. By introducing GLONASS IFDB, several tests are performed using observations from several IGS stations. Results show that the navigation accuracy isremarkably improved by adding GLONASS IFDB.
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jgg. 2013, 33(3): 106-110.
The inversion of strain (rate) parameters based on total least squares (TLS) is studied, not only considering the error of observation(displacement or velocity field), but also considering the error effects of the coefficient matrix generally composed of monitoring points coordinates. All calculation formulae of crust strain (rate) parameters inversion based on total least squares (TLS) using monitoring points displacement or velocity field are deduced. Because there are constant part independent from monitoring points coordinates and coordinates part in the coefficient matrix, it is divided into two parts. The stochastic model of strain parameter inversion using coordinate displacement with TLS is solved by matrix vec operator. Through a simulated example, the comparisons and analysis of strain (rate) parameters are carried out between the total least squares (TLS) results and least squares (LS) results. The rationality and effectiveness of total least squares (TLS) in crust strain (rate) parameters inversion are confirmed.
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jgg. 2013, 33(3): 111-115.
A method of the extraction of ridge lines and valley lines from mountainous LIDAR ground point cloud is presented. We extracted the normal vector and curvature of ground data based on differential geometry theory and local polynomial fitting，acquied the ridge points and valley points by computing extremum coefficient of curvature, generated ridge lines and valley lines based on the principle of minimum spanning tree. The results show that the method is feasible and effective.
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jgg. 2013, 33(3): 116-120.
In order to improve the accuracy and reliability of forecasting deformation rnonitoring data, two kinds of combination prediction model structure, series combination（SC)and parallel combination(PC） are proposed.In the SC time series model, grey model and neural network to predict are separately used and then
the predicting results are combined. In the PC the weight is used to combine different models, and the performance of the linear and nonlinear weight combination forecast are compared. Finally, a practical prediction case in building safety monitoring forecast used to explain the method. According to the experimental results, the proposed SC and PC combined method obviously can improve the prediction accuracy and therefore can be applied to deformation data analysis. -
jgg. 2013, 33(3): 121-124.
We take the combination of GPS and Beidou as the information transmission method to meet the accuracy in command and control applications in the special background. Meanwhile,we propose a method of command and control by network Beidou commander, so a serverside Beidou commander can command and monitor multiclient user machines remotely. The establishment of a “one to more” communication model increases the Beidou commander’s utilization. The system uses the combination of B / S and C / S as the WebGIS model which expanding the functions of the system and compatibility. Finally, on the basis of the above key technical the paper designs and completes a WebGIS monitoring system based on network Beidou commander, and the system has made a good application in practice.
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jgg. 2013, 33(3): 125-128.
The global ionospheric maps and international reference ionosphere as common ionosphere model are described. Observations in 2011 derived from three ionosondes in China are analysed. Comparative analysis between the measured data in China with global ionospheric maps and international reference ionosphere are represented in the work. The result indicates that global ionospheric maps is better than international reference ionosphere to describe the variation of electron content of ionosphere, and the accuracy of IRI2011 which is the latest version of international reference ionosphere is much higher than IRI2007.
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jgg. 2013, 33(3): 129-132.
The ability of polynomial fitting for detecting and correcting cycle slips is strongly affected by the errors of the carrier phase observations and the intervals of the observation data. The observation data being divided into several pieces will improve the results, however, the efficiency will be decreased.A method for combining epochdifferenced with robust estimation to improve the method of polynomial fitting is proposed. The numerical experiment is performed by using the real data of GPS /GLONASS. The results indicate that the method of robust polynomial fitting is more rigorous in theory and more powerful in practice for detecting and correcting cycle slips comparing with the normal polynomial fitting method.
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jgg. 2013, 33(3): 133-135.
In order to guarantee the reliability and availability of users’ positioning of Hebei CORS, ionosphere residual integrity monitoring indicator and ionosphere residual interpolation uncertainty indicator are used to conduct ionosphere integrity monitoring of the data of this network. The results show that the ionosphere delay calculated by these data within the decimeter level, and they are stable
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jgg. 2013, 33(3): 136-140.
A mathematic model of combined GPS/GALILEO single point positioning (SPP) is developed. On the basis of error corrections, the combined GPS/GALILEO SPP model is tested using the data of the MGEX tracking stations. The results indicate that the accuracy of the GPS/GALILEO SPP is not significantly improved when adding only one or two GALILEO satellites when the GPS observation satellites are sufficient. However, in the condition of insufficient number of GPS satellites, the accuracy of the combined GPS/GALILEO SPP is better than the GPSonly SPP.
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jgg. 2013, 33(3): 141-143.
According to the poor precision of the triangular meshes geometry information extraction and the complicated local highorder surface fitting program of the scattered point cloud, the local nth order surface fast fitting method and its curvature estimation formulas are deduced, which are on basis of the parametric local point cloud data, and the curvature calculation accuracy of the local quadric, cubic and fourth surface fitting has been compared by two practical examples. The comparison results verify that the theoretical formula is not only convenient to programming implementation, but also can ensure the calculation accuracy.
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jgg. 2013, 33(3): 144-147.
A soil pressure meter based on the principle of forcefrequency linear relationship of ATcut quartz crystal resonator was introduced. The pressure meter consists of three perpendicular pressure sensors，a temperature sensor and an acquisition. The test results show that the sensor range is 0 ~ 1.0 MPa; the nonlinearity is less than 1.0%, the repeatability error is less than 0.05%; the dely error is less than 0.1%, and the temperature measurement accuracy is better than 0.01 ℃
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jgg. 2013, 33(3): 148-150.
A highaccuracy horizontal reference device is very important for verification of instrument of surveying and metering. At present the debugging of highaccuracy horizontal reference device is menmade，which wastes much time and with large error，therefore，it is necessary to make this equipment automation retrofits.
The uncertainty analysis image measurement system after upgrading was studied by the combination of evaluation methods using standard of class A and class B,the results show that the transformation accuracy can meet the requirements of metrological verification. -
jgg. 2013, 33(3): 151-154.
To recognize the magnetic storms automatically from the horizontal component
of geomagnetism, a combined method of magnetic storms recognition based on Fisher and kernel Fisher discriminant analysis is presented. The data used in the study are derived from Ming tombs of Beijing geomagnetic station. In the case of the little number of the data samples, the average rate of this combined method for magnetic storms recognition is above 85%, and the recognition rate will be improved by the increasing amount of data samples. -
jgg. 2013, 33(3): 155-157.
We have designed an automatic monitoring system for railway roadbed subsidence. The monitoring system is composed of sensor subsystem, data acquisition, transmission subsystem and data management subsystem. By means of remote realtime monitoring, it can monitor and issue the situations of subsidence of railway roadbed.
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jgg. 2013, 33(3): 158-159.
Gravity measurements in Laos and Myanmar are reported.
