21 April 2014, Volume 34 Issue 2
-
Select all|
-
jgg. 2014, 34(2): 1-5.
Based on computation of grey relation degree，using observation data of mobile crossfault deformation up to May 2013，new synthetic norms for striketensilevertical activity parameters
of Xianshuihe，Longmenshan and Anninghe fractures，within radius of 300 km from the Lushan earthquake，are given，in order to search for the possible middleshortterm abnormities and timespace features，analyze coseismic deformation or influence.The results show that，1）About a few months to one year before the Lushan earthquake，at the region within radius of 300 km from the epicenter，there existed fault deformation abnormities to some degree，mainly located at the Xianshuihe fracture，Baoxing site of the southern segment of Longmenshan fracture and the vicinity of the southern end of Anninghe fracture； The obvious and concentrate turning deformation possibly had shortterm prediction meaning.2）Baoxing site only 26 km away from the epicenter displayed obvious coseismic thrust deformation； Totally the influence from this earthquake to other sites was weaker； Recently continued turning and jumping abnormities of this study area also possibly reflected the relationship with future strong earthquakes to some degree. -
jgg. 2014, 34(2): 6-9.
Taking the ground subsidence in Taiyuan city as an example，we employ PSInSAR technique with 20 scenes of ENVISAT ASAR images acquired between August 2008 and September 2010.Twodimensional linear regression analysis method is applied to achieve the annual vertical deformation rate map and timeseries deformation maps.It proves PSInSAR results are highly consistent with insitu leveling measurements.
-
jgg. 2014, 34(2): 10-13.
Difference between geoid and reference ellipsoid called geoid undulation.Bouguer gravity anomalies are widely used in density inversion，however，the effects of geoid undulation on gravity were not considered in traditional gravity corrections during the calculation of bouguer gravity.Effects of geoid undulation on gravity were calculated，and bouguer gravity anomalies under consideration of the effects were obtained，as well as，the gravity effects and its relative ratios to bouguer anomalies were analyzed.The results indicate that both of them is coherent with terrain distributions，the largest effects of geoid undulation on gravity locate in basins while the largest relative ratios locate in the third terrain ladder of China mainland.It is suggested that the gravity effects of geoid undulation should be considered when bouguer gravity anomalies were used to invert and interpret density structures，especially in the third terrain ladder of China mainland and basin areas.
-
jgg. 2014, 34(2): 14-17.
In frequency domain，the gravity isostasy on Shatsky Rise was studied by 3D admittance analysis of gravity anomalies and bathymetry，referenced to Airy and Flexural isostatic models respectively.According to Airy model，it indicates that the mean crust thickness of Shatsky Rise is about 15 km，and the depth of Moho discontinuity beneath Tamu massif is about 26 km，which is consistent with the result that given by seismic studies.According to flexural isostatic model，it shows that the effective elastic thickness of lithosphere around Shatsky Rise is 1~5 km.That means the rise is an “On Ridge” structure.Taking into account both the topography and material loading at the bottom of the crust，the result shows that the amplitude of material loading at the bottom of the crust is about 50 ％ of the topography，and the average loading depth is 20 km.Shatsky Rise may be supported by the buoyancy of bottom loading mainly.
-
jgg. 2014, 34(2): 18-22.
《Specification for the first and second order leveling》 stipulates that the field of rivercrossing GPS leveling has to be flat.An experiment on both embankments of Chaobai River，where elevation difference of observing sites is less than 1 meter，was finished for verifying retionality of the specification.The result shows that the same embankment with height anomaly change rate （α）meets requirements.Two sides of the river with the height anomaly change rate of （α）is beyond the limit of the provisions，and elevation difference between calculated and actual measurement is 26.98 mm.So，first order rivercrossing leveling must abide the specification.
-
jgg. 2014, 34(2): 23-26.
Present crustal velocity field and distribution features of present tectonic strainin in Bayan Har block and its surroundings were calculated with GPS data of CMONOC and GNSS continuous tracking station，using the graphic element strain model.The calculaed results were compared with the geodynamic background.
-
jgg. 2014, 34(2): 27-30.
The results of simulation and ground measurements show that there is obvious nonlinenar variation in vertical gradient of gravity from the ground surface to a height of 80 cm and 130 cm，the amount is more than 002×10-8ms-2/cm，and the variation of gradient increscent with the changes of elevation.Therefore，the difference caused by height has to be paid attention in gravity measuring with FG5 and A10 absolute gravitymeter
-
jgg. 2014, 34(2): 31-35.
The results of the influence of seasonal variations of temperature and sunshine on the observation pier’s stability were introduced，based on the analysis of GNSS continuous observations data from different types of observation piers in GNSS Tangshan test field.The results indicate that：1）The variation of the observation pier includes long term tendency variation and a significant annual variation which is mainly caused by seasonal changes of precipitation and temperature.2）Stability of the observation pier is affected by external environment.For instance，the annual changes of the pier in the indoor is smaller than the outdoor.3）In the current observation condition and precision，the pier with a height of 3.5 m outdoor can not reflect any diurnal periodicity motions related to the sun.
-
jgg. 2014, 34(2): 36-40.
Characteristics of crust motion，locking ratio and fault activity of the study area were analized based on a negative dislocation with horizontal GPS velocity data from 2009 to 2011.The study area is divided into 4 blocks by YadongGulu rift and YarlungZangbo Suture.Taking the Southwest Block as a reference point，Euler pole（EP）of Southeast Block is 89.37°，27.91°，-2.56°/Ma，EP of Northeast Block is 89.02°，28.94°，-2.87°/Ma，and EP of Northwest Block is 85.03°，27.98°，-0.93°/ma.Difference of velocity between sites in the north side of YarlungZangbo Suture and the sites in the south side of YarlungZangbo Suture indicates that the Suture is a strikeslip fault with a rate of 6.75±0.9 mm/a in the southern section，and 4.72±0.8 mm/a in the narthern section both of them are larger than that from geological observation.According to the inversion result，the locking depth of YadongGulu rift is 10 km，less than most faults.
-
jgg. 2014, 34(2): 41-44.
Laser tracker with high accuracy is often used to survey with known control points in process of application.For meeting the demands of track geometry parameter measurements，a kind of connection device and surveying method was introduced.The device connects SMR target sphere and track control points installed optical reflector SMR target sphere and is used in the place where the track control points are known.The method is to survey the position difference between SMR target sphere and the center of Leica prism.The relevant specifics precision index of the two kinds of prisms is given.
-
jgg. 2014, 34(2): 45-50.
Evolution of horizontal displacement of nodes at the internal side of a fault is modeled numerically by use of FLAC3D，and distribution and evolution of regions where the sign of horizontal or vertical displacement of monitored nodes changes are also presented，based on the proposed heterogeneous and strain softening constitutive model.Result indicates that the reverse displacement phenomenon occurs during the jog failure for both echelon faults.However，the reverse displacement regions differ greatly for different echelon faults.For extensional echelon faults，the regions are large，and basically distribute outside the jog.For compressive echelon faults，the regions only locate in the jog and its adjacent faults.
-
jgg. 2014, 34(2): 51-54.
Atmospheric refraction index is one of the primary problems in theoretical atmospheric refraction research.A theoretical formula of the relationship between atmospheric refraction index and meteorological parameters was presented，based on the consideration for the influence of quadratic term in the ratio of the pressure and temperature on refractive index.The result indicates that it has to consider present precision measurement range.Moreover，according to electromagnetic medium dispersion theory，a theoretical model of group and phase refraction index with wavelength change，which could be transformed reciprocally for the same or different band was proposed.That means that it is feasibe to study atmospheric refraction delay in radio waveban using boptical astronomical observation
-
jgg. 2014, 34(2): 55-59.
The propagation law of errors in total least squares（TLS）was proposed. The covariance matrix of the first column vector can be determined when the first column vector equals the product of one variable matrix and the second column vector, and the variance and covariance of all the elements in the variable matrix are known. The propagation law of errors between two relevant variable matrixs can be reducted. Some examples indicate that the law is effective.
-
jgg. 2014, 34(2): 60-63.
According to the extraction of GPS coordinate series in Sutong Bridge, db6 wavelet function decomposes the same monitoring point time series for different time observations into five layers and denoising processes, and gets noise sequences. Then we analyze the signal noise characteristics of GPS coordinate component by using the method of maximum entropy spectrum estimation, and compared with the method in traditional spectrum analysis. The results indicate that GPS coordinate time series mainly contain white noise and flicker noise, the random walk noise is not obvious. So that, analyzing the time series obtained by the GPS observation, the noise property should be taken into account and the observations should be weighted correctly in order to fit the actual situation.
-
jgg. 2014, 34(2): 64-68.
Ambiguity resolution based on conventional ionosphereweighted model usually needs prior information about ionoshperic delay.A new ambiguity resolution for network RTK based on improved ionosphereweighted model is proposed for the situation without prior information.Firstly，the ionospheric pseudoobservations and stochastic model are constructed through carriersmoothed code.Then，the Kalman filter mode based on ionosphereweighted function is established.at last，the adaptive Kalman filter algorithm is introduced，so as to adjust parameters evaluation tolerance caused by model inaccuracy.Experiment shows that this new method possesses fast convergence and well stability.It is suitable to longrange network RTK，particularly to the satellites with 20°or more elevation angle.
-
jgg. 2014, 34(2): 69-73.
This paper aims at sharing map symbols.We first compare structures between ArcGIS point symbol and Path Based（PB） point symbol.And then we analyze morphemic structures of point symbols and evaluate the versatility of path based point symbol model.Based on the PB symbol model,we present the mapping modes of symbol data and propose the ArcGIS point symbol sharing method from primitive symbol,character symbol and picture symbol class.The experiments suggest that ArcGIS point symbols can be shared by using path based point symbol model.The approaches will help us improve symbol sharing between cartogaphic systems.Therefore,efficiency of map production can also be improved.
-
jgg. 2014, 34(2): 74-78.
Static data were conversed as dynamic modal using dynamic Precise Point Positioning（PPP）technique.Comparison of the Zenith Tropospheric Delay（ZTD）of the dynamic PPP to the ZTD of static PPP indicates that the dynamic PPP technique by using higher sampling interval SCBs（30s or higher）can also obtain highprecision ZTDs.This study provides a new method to achieve water vapor acquisition.
-
jgg. 2014, 34(2): 79-83.
A new signal denoising method based on ensemble empirical mode decomposition is presented.Firstly the signal is decomposed by EEMD.The boundary of signal and noise is identified primarily based on consecutive mean squared error criterion.Finally the indexes of mean period and energy density also their product are used for the signal denoising.The denoising effect is presented and valid through GPS height time series experience of two national CORS stations.
-
jgg. 2014, 34(2): 84-89.
A new approach based on theoretical reflectivity seismograms gainning Moho structure was proposed in the paper. The ratio of PmP and Pn’s wave amplitude and adjusts model were used to fit the predicted PmP/Pn curve with measured PmP/Pn curve. Experimental tests indicate that there exists significant difference among the theoretical PmP/Pn curves of Single Layer structure, Gradient Layers structure，layers stacked with high and low velocities structure. SL structure is similar to GLS structure’s PmP/Pn curve in the shape, however, the value of the former is roughly twice that of the latter, and HLVS structure’s PmP/Pn curve appears in concave shape. All shows that this method is sensitive to Moho structure and can be used to identify effectively of Moho structure.
-
jgg. 2014, 34(2): 90-94.
To improve the data classification effect of LiDAR points filtering, a method of morphological opening by reconstruction is proposed on the basis of traditional morphological filtering algorithms. In this method, marker image will be got from grid DSM by erosion firstly, then opening by reconstruction process is finished through geodesic dilating on the marker image repeatedly. Finally, nDSM is achieved by white tophat reconstruction to realize correct classification of ground objects and ground points. The experimental results with ISPRS data show that this approach is able to classify ground and nonground points effectively. Mean error of typeⅠis 351%, mean error of type Ⅱ is 7.20% ,and total error is 4.26%. Under the condition of error of typeⅡkeeps the same level, mean error of typeⅠand total error are minimum, compared to traditional filtering methods.
-
jgg. 2014, 34(2): 95-99.
By Euler’s theory, the plate motion error model was established. According to robust estimation, a new method was proposed,which can both detect the abnormal stations automatically and acquire motion parameters quickly at the same time. For global 9 plates，the position and size of the abnormal stations was detected accurately and global plate motion model based on ITRF2008 was constructed successfully.The results show that the robust estimation before removing abnormal stations are as good as the least squares after removing the abnormal stations. Comparing with the models that other scholars researth, it’s consistant as a whole and higher obviously at accuracy.
-
jgg. 2014, 34(2): 100-104.
提出一种加权半参数模型，对半参数模型中的参数分量与非参数分量分别加权，针对数据的不同特点合理确定权重。分别对模拟数据和GPS真实数据进行处理，并与最小二乘法、岭估计法和半参数模型进行对比，通过残差、均方误差等指标的对比分析可见，加权半参数估计模型得到的估计值与真值最接近，估计残差浮动平缓，均方误差小。
-
jgg. 2014, 34(2): 105-110.
Taking 2012 January data as an example，effect of model order and observation data sampling intervals on global ionospheric modeling time and accuracy of the model，and the correlation between the magnetic field intensity and the accuracy of the model were analized.The results show that the model order and the sampling interval affect greatly modeling time and accuracy of the model，and there is a strong correlation between the geomagnetic intensity and the accuracy of the model.Therefore，reducing model order and sampling rate can greatly reduce the modeling time required duaring the geomagnetic quiet perids.
-
jgg. 2014, 34(2): 111-114.
A novel model based on empirical mode decomposition and gene expression programming for landslide deformation prediction is presented.From the perspective of timefrequency analysis，firstly，deformation time series was decomposed into different frequency component through the empirical mode decomposition.Then，a program is constructed for the approximate series and detail series using gene expression to get prediction results.Finally，the results were composed.Experimental result indicates that the prediction presision is higher than GM(1，1)，AR and LSSVM.
-
jgg. 2014, 34(2): 115-119.
Ionospheric delay was obtained with day’s observation data from Compass GEO satellite，based on dualfrequency ionospheric correction model.The robust spectral analysis method was applied to analize ionosphere delay data for detaching the long term，period terms and random errors and controlling the effects of error on the terms.In order to control the influences of colored noises，the residuals are fitted by using an AR model.The result shows that the ionospheric correction is effected by not only trend term and period term changes，but also by color noises.After being fitted by piecewise polynomial，period terms and color noise，the ionospheric correction residual terms turn out to be white noises.The result proves the method is seffective.
-
jgg. 2014, 34(2): 120-123.
Effects of fog and haze weather on GPS zenith tropospheric delay and precipitable water vapor was presented in the paper，based on the data of GPS continuous observation network in Beijing.The results of the study show that zenith tropospheric delay and precipitation water vapor rise in the fog and haze weather，zenith tropospheric delay and precipitation water vapor keep in the peak when fog and haze continue，and zenith tropospheric delay and precipitation water vapor decreased when fog and haze process ends.
-
jgg. 2014, 34(2): 124-127.
A method to solve a synthetic adjustment of absolute and relative gravity network using weighted constrains is presented.Robust estimation is applied to eliminate gross errors，and χ2 statistic is applied to a posteriori variance testing，and Student’s t test is adopted to test statistically the relevance of gravimeter’s parameters and to test whether the examination stations’ gravities are evidently changed.Some computing results show that，the ratio between the posteriori variance after adjustment and the priori variance of unit weight is 1.08，which satisfies a χ2 test，and the average error estimate of the unknown gravity values is ±13.6×10-8 ms-2，17 exterior examination stations’ gravities aren’t evidently changed.
-
jgg. 2014, 34(2): 128-131.
Synthesis method of ndays orbit with oneday orbit based on pseudostochastic parameters is present.The method is validated using GPS real data.The calculated results show that the method is correct and effective.The precision and smoothness of oneday orbit solution is improved effectively.Especially，the phenomenon of orbit jump is improved obviously by added pseudostochastic parameters at the edge of one day.
-
jgg. 2014, 34(2): 132-136.
The accuracy of 30 and 365 days prediction value of ERP were respectively analyzed，as well as their impact to astronomical geodesy were analyzed.Analysis results show that：the 365 days prediction values of polar motion and 30 days prediction values of length of day（LOD）could be used in astronomical longitude and latitude measurement，and 365 days prediction values of ERP could be used in astronomical azimuth measurement.
-
jgg. 2014, 34(2): 137-141.
The differences among SINS mechanization methods of rotation vector, quaternion and Taylor expansion were analyzed, the results indicate that the posture expression and the appropriation degree of algorithm are main reasons caused different calculation precision in those methods. A velocity constraints method and corresponding Kalman filter model were proposed. Test results show that higher accuracy can be obtained by Taylor expansion method for high accuracy analog data, and greatly delay navigation time cab be delayed by velocity constraint method for low accuracy analog data.
-
jgg. 2014, 34(2): 142-145.
Simulation of onboard GPS data was completed using the simulation model of Bernese software.With the observation data obtained from simulation，The influence of different gravity field models（GEMT3、JGM3、EGM96、TEG4、EIGEN2 and EIGENGL04C）on the accuracy of orbit determination in loworbit satellites was analized by simplified dynamic orbit determination method.The results show that the simulation data is consistent with actual situation，which can meet the need of a variety of experimental analysis.The influences of different gravity field models and degree on the accuracy of orbit determination are different，and the best result with the models generated from CHAMP’s and GRACE’s gravity data were achieved.Compared to the other gravitational field models，the accuracy difference of orbit determination with the method is in centimeter level.
-
jgg. 2014, 34(2): 146-149.
Generally，GPS users often apply no estimation of the tropospheric delay to short baselines.To study the influence of the estimation of the tropospheric delay on the short baseline with big height difference，20 hours of continual GPS observation data of a 1.2 km short baseline with the height difference of 156m were collected by 2 leica1200 GPS receivers.The result from GAMIT 10.4 shows that there is a no apparent influence on the horizontal components，and the height repeatability is still good，without the estimation of atmospheric delay，however，in which condition，systematic errors on the up direction will be included.
-
jgg. 2014, 34(2): 150-154.
Highfrequency observations of 12 Continuous Operational Reference System（CORS）GPS stations in Tianjin were processed with precise point positioning（PPP）and relative difference positioning（PRP）to estimate the absolute and relative epochbyepoch positions.The Modified sidereal filtering was used to correct multipath effect of highfrequency position time series.Positioning precision of PPP for east，north and vertical components are 7.3 mm，7.1 mm and 16.0 mm，respectively.The precision of PRP for east，north and vertical components are 5.0 mm，5.2 mm and 14.7 mm，respectively.Compare to PPP，the precision of PRP is improved as 1.3 mm to 2.3 mm.According to the power spectral density，the noise is not only white noise.For PPP，the noise at frequencies below 0.1 Hz decreases with frequency and becomes flat at higher frequencies.However，for PPP，the noise at whole frequency band decreases with frequency.The difference of noise between PPP and PRP occur at high frequencies up 01HzAnd then，the spectral indexes of power law noise are estimated simultaneously with amplitude of white noise using maximum likelihood estimation.The white noise amplitude of PRP is much larger than PPP’s.The noise of PRP can be best described by a combination of white noise plus random walk noise.However，the noise of PPP can be best described by a combination of flicker noise plus white noise.
-
jgg. 2014, 34(2): 155-160.
According to GOCE and GRACE are complementary in the spectrum of earth gravity field，spectral combination method combined GOCE and GRACE geopotential coefficients was studied.The spectral combination formulas are established based on the coefficients’ error degree variance weighting，error variance weighting and block diagonal error covariance weighting.As a test，the GRACE gravity field model ITGGRACE2010s and GOCE gravity field model GO_CONS_GCF_2_DIR_R1 are used for calculating and checking the spectral combination method.The results show that the accuracy of the combined gravity field models established by these three kinds of spectral combination methods is higher than the GRACE or GOCE’s independent model，and their total accuracy is superior to GOCO01S model which is based on GOCE and GRACE.Spectral combination method based on the block diagonal error covariance weighting is relatively optimal in these three kinds of weighting schemes，because it considers the correlation among the coefficients of same order m.
-
jgg. 2014, 34(2): 161-164.
Regional GPS continuous observation data combined CMONOCGPS data and IGS data were processed with different satellite ephemeris and reference frames，and coordinate series repetition rate and velocity are compared.The results show that，if global distribution sites are selected as a reference frame，the station coordinates and velocity calculated are more close to absolute geocentric datum，however the periodic variation of each station is treated as error in the processing，the coordinate repetition is relatively poor; if the sites near the research region are selected as a reference adjustment datum，the periodic variation is weaken by the similar transform parameters，part of the regional common mode error is eliminated，and the selfconsistent of results are improved.A reasonable calculation scheme to get regional deformation information is to build a stable reference frame by adding the regional results into global solutions step by step.
-
jgg. 2014, 34(2): 165-168.
The relation of residual GPS site vertical residuals distribution and geographic location of GPS sites were analized with ITRF2008 data.The result indicates close relation of residual distribution to geographic location of GPS sites，and which is caused by seasonal temperature change.
-
jgg. 2014, 34(2): 169-174.
Precise satellite clock corrections over 1 year provided by IGS are analyzed to find out the periodical character of satellite clock corrections.The modified Allan deviation（MDEV）of each GPS and GLONASS satellite is calculated to analyze the timefrequency stability and the type of noise in the atomic clock.Periodic character of satellite clock corrections and temporal variation of amplitude corresponding to each peak are analyzed in detail.Results show that：1）Spectral peaks are found on amplitude spectrum of GPS and GLONASS satellites with periods corresponding to 1 circle，1/2 circle，1/3 circle，1/4 circle of the satellite orbit period respectively while GPS’s peaks are clear and GLONASS’s are not；2）Removing the periodic signal，obvious changes are visible in the MDEV of GPS satellite clock corrections，but not in GLONASS.This indicates that the periodic signal is strong in GPS satellite clock corrections，but not in GLONASS；3）Comparisons of amplitude of satellite clock corrections over different time shows that variation of amplitude varies with time.
-
jgg. 2014, 34(2): 175-178.
A regression model of spatial relationship between different continuous stations was constructed using a multiple linear regression method，based on the GNSS continuous data of Yunnan Province.The results show that the multiples linear regression models can simulate the relationship between stations；before earthquake events occur，the relationship will be changed.
-
jgg. 2014, 34(2): 179-182.
In order tosatisfy actual demands，a set of auxiliary observation device was designed to measur environment parameters for relative gravimeter e.g.，temperature，pressure，tilting.Result of tests，indicates that the device meets the design requirements.
