大地测量与地球动力学
 
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2013 Vol.33 Issue.4
Published 2013-08-16

1 BACKGROUND OF VERTICAL DEFORMATION BEFORE WENCHUAN 
Ms8.0 EARTHQUAKE
Ta La,Chen Fuchao,Guo Liangqian,Chen Juzhong,Bo Wanju

Based on the data obtained since 1951 and the crustal vertical deformation rate calculated from the GPS data obtained from 1999 to 2007, the vertical deformation characteristics in QinghaiTibet block and southern China block, and the relationship between the vertical deformation and both of the occurrence and the development of Wenchuan Ms8.0 earthquake was studied. The results show that Wenchuan Ms8.0 earthquake happened in the vertical deformation rate gradient zone that was the dramatic rising area.The accumulation of deformation strain energy was related with collisions of the IndianEurasian plates, and the vertical uplift of the QinghaiTibet block by strong squeeze in NorthSouth direction at the front edge of the collision of the two plates with the substance movement to the East and SouthEast.

2013 Vol. 33 (4): 1-3 [Abstract] ( 1128 ) PDF (719 KB)   ( 3202 )
4 STUDY ON RECONSTRUCTING 3D COSEISMIC DEFORMATLON 
FIELD BASED ON SAR IMAGES
Liu Bin,Zhang Jingfa, Luo Yi, Jiang Wenliang,Li Yongsheng

Taking the 2008 Gaize earthquake as an example, we use InSAR and MAI techniques to measure line of sight (LOS)and azimuth (AZI)deformations, respectively.InSAR+AZI(model 1)and MultiLOS(model 2)models are applied to reconstruct 3D coseismic deformation fields, Compared with simulations, we discover that the deformations in eastwest,vertical directions of the two models are consistent with each other; however, in northsouth direction, the results of model 1 are tally with the actual situation, while massive distortions occur in that of model 2.

2013 Vol. 33 (4): 4-8 [Abstract] ( 1200 ) PDF (2760 KB)   ( 3193 )
9 RESEARCH ON FAULT MOTION AND SEGMENTATION CHARATERISTIC 
OF KOUQUAN FAULT IN DATONG BASIN BY NUMERICAL SIMULATION
Li Yuhang,Wang Qingliang, Cui Duxin,Hao Ming, Ji Lingyun, Qin Shanlan

Using the GPS observation results of 1999—2007 and 2009—2011 as the constraints, and based on the method of threedimensional finite element, the fault motion and segmentation characteristic of Kouquan fault in Datong basin were analyzed. The  results show that the fault is more active in the middle part than the either side. The rightlateral velocity of the fault is 0.8 mm/a and its normal velocity is almost 1.5 mm/a in the middle part of the Kouquan fault.

2013 Vol. 33 (4): 9-12 [Abstract] ( 1247 ) PDF (1459 KB)   ( 2870 )
13 CRUSTAL DEFORMATION CHARACTERISTICS AFTER Ms8.0 
WENCHUAN EARTHQUAKE IN SICHUAN-YUNNAN REGION
Dang Xuehui,Qiao Xuejun, Zhao Bin,Lü Jian,Wang Hengxin,Zhang Yunlong

The velocity field of the 296 stations in the SichuanYunnan region has been obtained with the GPS observation data of the CMONOC from 2009 to 2011. Based on the continuous deformation hypothesis, we use the data of the horizontal velocity field to compute the distribution of horizontal strain field in this region by the triangle method. Preliminary analysis indicates that: 1) In SichuanYunnan region, the crustal movement of north and west is stronger than that of south and east. The SichuanYunnan rhombic block is characterized by clockwise rotation. 2) The directions of the principal compressive strain axis and the P axis of the focal mechanism solution show that tectonic stress field in this region is relatively stable in a long term. 3) The high value areas of the principal strain and the maximum shear strain rate are in the Longmenshan fault zone and its surrounding region. In addition to the above areas, the significant highvalue properties of the maximum shear strain rate can be seen in the south of the Xianshuihe fault zone and the northwest segment of the Red River fault zone.

2013 Vol. 33 (4): 13-16 [Abstract] ( 1285 ) PDF (1241 KB)   ( 2675 )
17 ANALYSIS ON QINGHAI-TIBET PLATEAU STRAIN FIELD BASED 
ON MULTI-SURFACE FUCTION
Wu Xiaolong, Yang Zhiqiang, Wu Jifeng,Hu Yang

Combined the method of curve fitting when calculating a lowerfrequency strain field in a large area with the strain tensor matrix on the earth reference ellipsoid, we put forward a method of calculating strain parameters on reference ellipsoid by using multisurface function. According to the GPS data, we get the QinghaiTibet plateau strain field. The result is in line with both characters of the major tectonic activity within this area and the main direction of P,Taxis from focal mechanism solutions

2013 Vol. 33 (4): 17-21 [Abstract] ( 1065 ) PDF (1304 KB)   ( 2656 )
22 PCA METHOD IN DETECTION OF IONOSPHERIC TEC ANOMALIES 
BEFORE EARTHQUAKE
Tang Jun, Yao Yibin, Chen Peng,Zhang Shun

We analyzed 17 M≥6.0 earthquakes which occurred in the mainland of China from 2007 to 2011 by Total Electron Content (TEC) provided by IGS web. We used Principal Component Analysis(PCA) method to detect the TEC anomalies over the epicenter and compared with the method of sliding window statistics. The results show that the PCA analysis is not affected by geomagnetic storm, and broadly consistent with the results of the analysis of the two statistical methods. There are significant abnormalities in the same time and space. Ionospheric TEC anomalies are mainly concentrated in the 0-5 days before the earthquake.

2013 Vol. 33 (4): 22-25 [Abstract] ( 1259 ) PDF (1097 KB)   ( 2888 )
26 EARTHQUAKE HAZARD ANALYSIS OF DATENGXIA RESERVOIR 
GUANGXI REGION
Zhang Lifen,Li Jinggang,Wang Qiuliang, Zhou Bin,Li Xiguang

Earthquake hazard of Datengxia reservoir in Guangxi region is analyzed using the selfmade software. The whole reservoir is divided into five segments, and eight factors are chosen to calculate the magnitude probability and the corresponding intensity of each segment. The results show that it is possible for the moderatestrong earthquake occurring in Kuwei to Lema and Daduwan to the dam after impoundment, the probabilities are 0.499 and 0.272, respectively. It is less likely to occur earthquake in the three segments between Lema and Daduwan. Under these circumstances, the epicentral intensity of the Kuwei to Lema and Daduwan to the dam segments will reach VI based on the intensity attenuation relationship of reservoir induced earthquake, and the lengths and widths of the isoseismal are 6.7 km, 3.8 km and 5.9 km, 3.3 km, respectively.

2013 Vol. 33 (4): 26-30 [Abstract] ( 1254 ) PDF (591 KB)   ( 2851 )
31 ANALYSIS ON COSEISMIC EFFECT OF GROUNDWATER FROM 
THREE GORGES WELL NETWORK
Zhang Weihua, Wang Qiuliang, Li Jinggang, Luo Junqiu,Guo Xizhi

The paper studies the different coseismic changes of water level caused by the M85 Sumatra earthquake on Sep.12 in 2007, the M90 Japanese earthquake on Mar.11 in 2011 and the M80 Wenchuan earthquake on May.12 in 2008 and local earthquakes in the Three Gorges area between Sep and Nov in 2008 through the Three Gorges well network, the mechanism is explained. Corresponding relationship between coseismic changes of water level and parameters of teleseism and local earthquakes is deduced.

2013 Vol. 33 (4): 31-35 [Abstract] ( 1164 ) PDF (1257 KB)   ( 3219 )
36 RESEARCH ON ACTIVITY OF QINGSHANKOU-HUANGPI FAULT
Hu Jian, Lei Jingya, Wang Xutao, Huang Jiang,Wang Lan

According to the requirements of the project, we undertook research on the activity of QingshankouHuangpi Fault. In this study, we measured gaseous mercury in soil and electromagnetic field along 4 lines accrosing the Fault by XG4 digital mercury analyzer and very low frequency analyzer. The measure data indicate that contenents of intensity of gaseous mercury in soil and electromagnetic is closely related to fault activity. In the active sections of the fault, abnormality of gaseous mercury in soil and electromagnetic field are much higher than that in the stable sections.The results mean that the two methods above can be used not only to confirm the location of faults,but also can be used to analize intensity of an active fault.

2013 Vol. 33 (4): 36-38 [Abstract] ( 1130 ) PDF (787 KB)   ( 2756 )
39 OBSERVATIONAL DATA ANALYSIS OF VERTICAL GEOELECTRIC 
FIELD IN TIANZHU AREA, GANSU PROVINCE
Yan Rui, Wang Lanwei, Zhang Shizhong, Liu Dapeng, Hu Zhe, Zhang Xingguo,Zhu Xu,Zhang Yu

Combining with horizontal geoelectric field data in Hongshawan, Huangyangchuan and Songshan stations in Gansu province, the vertical geoelectric field data of three years observed in the three stations are studied. The results showed that:1)The obvious and stable annual periods of sinusoidal shape were found from vertical geoelectric field data in the three stations, but the value and the phases of an annual variation period are different.2)The impending anomalies before the earthquakes recorded by the vertical geoelectric field from Hongshawan station agreed with the earthquake occurrence in time and space. But whether the anomalies were caused by the earthquakes, a further research is needed.

2013 Vol. 33 (4): 39-43 [Abstract] ( 1134 ) PDF (961 KB)   ( 2680 )
44 ANALYSIS OF LONG-TERM ABSOLUTE GRAVITY CHANGE 
AT JIXIAN DATUM
Xiao Fan, Zhang Weimin, Zhang Songtang, Zhang Hongwei

The yearly rate of gravity change owing to elevation changes and underground material transfer were calculated using 10 years measurement results of absolute gravity and GPS at Jixian datum. The results show that the technology of monitoring tiny vertical crust movement using highprecision absolute gravimeter is rapid, efficient and no error accumulation. In addition, the loss of underground water of Jixian is serious in recent years.

2013 Vol. 33 (4): 44-47 [Abstract] ( 1199 ) PDF (694 KB)   ( 3071 )
48 MODEL OF CRUSTAL VERTICAL MOVEMENT VELOCITY FIELD 
BASED ON HEBEI CORS NETWORK
Chen Xing,Cheng Pengfei,Cheng Yingyan, Fan Wentao,Wang Xiaoming, Wang Fuli

The vertical crustal movement velocity field in Hebei is calculated using the GAMIT/GLOBK software with GPS observational data of the firststage stations of Hebei CORS network in the past four years. The results show that the mainly vertical crustal movement is a downward motion and that southeast plain region is a serious settlement area in Hebei. The cumulative subsidence in the past three years is more than 150 mm in part areas. And the vertical descent rate in November is faster than that in April. The larger difference of rate has more than 10 mm/a. The model of vertical crustal movement velocity field in Hebei is established based on the method of multiquadric functions and 6′×6′grid velocity is calculated and the isoline map of vertical movement velocity is drew.

2013 Vol. 33 (4): 48-51 [Abstract] ( 1124 ) PDF (699 KB)   ( 2984 )
52 FAST CALCULATION OF EARTH’S DISTURBING GRAVITY THROUGH 
POLYNOMIAL FITTING
Wang Jianqiang, Li Jiancheng, Zhao Guoqiang, Xu Xiaobo

An orbit gravity field was simulated through the EGM2008 with ultrahighdegree, and then the gravity field was approximated by polynomial fitting with divided segmentation of the orbit. According to the different segmentations and polynomial fittings, a test was done which focuses on the precision, data storage and calculation speed of the polynomial fitting. The results show that: comparing with traditional methods, the computing speed of the orbit gravity field by the segmentation polynomial fitting approximation improves 3 orders of magnitude, and data storage is less than 100 floating point numbers.

2013 Vol. 33 (4): 52-55 [Abstract] ( 1184 ) PDF (572 KB)   ( 3032 )
56 ON MIXED STRUCTURED TOTAL LEAST SQUARES FOR 
PARAMETERS ESTIMATION
Hu Chuan, Chen Yi,Peng You

〗In this contributions we defined the model of mixed structured total least squares according to the mixed least squarestotal least squares and proposed an iterative algorithm for the mixed structured total least squares problems, which solving by the nonlinear least squares adjustment theory. Three numerical examples are given at last,where assumes the errors of elements in observation vector equal ,greater and lesss than the error of independent elements in coefficient matrix ,respectively. It’s shown that the method represented in this paper would be able to estimate the parameters theoretically closer to the true value and attain the more precise mean square error of weight unit than least squares and mixed least squarestotal least squares, especially when the coefficient matrix which holds more errors than observation vector.

2013 Vol. 33 (4): 56-60 [Abstract] ( 1234 ) PDF (522 KB)   ( 3649 )
61 RELIABILITY STUDY ON SEDIMENTATION MONITORING FOR D-INSAR
BY USING ERA-INTERIM DATA AND NEQUICK MODEL
Ma Zhiquan,Chen Yanling,Chen Qinming,Yang Zhe,Gao Dezheng

Four images for ALOS PALSAR of the track 474 before and after Wenchuan earthquake are processed by the software ROI_PAC, and then  the tropospheric and ionospheric delay are corrected
by ERAInterim data and NeQuick model. The sedimentation is compared with that derived from five GPS observations, the results show that the mean value of the differences between the sedimentation derived from DInSAR and that from GPS observations is 0.104 m, which is 0.057 m when the sedimentation derived from DInSAR which the tropospheric and ionospheric delay are corrected. This illuminates that the accuracy of the sedimentation from DInSAR is improved after the tropospheric and ionospheric delay are corrected.

2013 Vol. 33 (4): 61-64 [Abstract] ( 1489 ) PDF (1028 KB)   ( 2988 )
65 MEAN DYNAMIC TOPOGRAPHY OVER CHINA SEA AND NEIGHBOUR
Peng Lifeng, Zhang Shengjun, Li Dawei, Zhao Qian

Using the GDR data recorded by the Jason1, Jason2 and Envisat altimetry satellites for three years, and on the basis of the geoid calculated by the GOCO02S gravity field model which is combined with GOCE and GRACE, the mean dynamic topography is calculated over China sea and neighbour using Pointwise approuch. The results show that different trends are reflected from mean sea surface and mean dynamic topography, which are consistent with the known results respectively

2013 Vol. 33 (4): 65-68 [Abstract] ( 1051 ) PDF (941 KB)   ( 2800 )
69 PREDICTION OF  LENGTH OF DAY BASED ON LS+AR MODEL  AND  
ACCURACY ANALYSIS OF DIFFERENT CYCLE TERM
Sun Zhangzhen,Xu Tianhe

After reviewing the prediction of LOD based on the LS+AR model, the influence of different cycle term on prediction accuracy is analyzed by using different combination of the main cycle terms. The results show that longterm cycles of 18.6year and 9.3year, the shortterm cycle of onethird year have great impact on LOD prediction accuracy. Therefore, it is recommended that the above three cycle terms should be taken into account in highaccuracy LOD prediction except for annual and semiannual cycle terms

2013 Vol. 33 (4): 69-72 [Abstract] ( 1341 ) PDF (1443 KB)   ( 3416 )
73 RESEARCH ON SPATIO TEMPORA UNIFICATION OF BDS/GPS/GLONASS
MULTIMODE FUSION NAVIGATION AND POSITIONING
Li Hefeng, Dang Yamin,Bei Jinzhong,Yang Fanlin

Time system and coordinate system are the reference datum for navigation and positioning, any form of navigation and positioning are carried out within a certain amount of time and coordinate frame. This paper detailed study spatio tempora unification among Beidou Satellite Navigation System (BDS), GPS and GLONASS, introduces the time frame and coordinate frame of the three navigation systems. Gives spatio tempora unification conversion model and parameters. On the basis of the theory, puts forward the spatio tempora unification method in practical application of multimode navigation and positioning. Based on the Visual C++ platform write multimode combinations positioning program, calculate and analyze BDS/GPS/GLONASS three system receiver data, experimental results show that, multimode fusion positioning have better accuracy and reliability. Verify the correctness and feasibility of spatio tempora unification transformation thought and method in practical application.

2013 Vol. 33 (4): 73-78 [Abstract] ( 1541 ) PDF (1404 KB)   ( 5121 )
79 TERRAIN RENDERING TECHNOLOGY BASED ON GEOMETRY CLIPMAP
Wang Yu, Sun Yongwei, Wang Mingwei, Song Xingshen

An improved Geometry Clipmap algorithm is presented, in which we increase the number of topographic data scheduling module, reconstruct the organization of the note, and introduce the progressive texture update technology. The experiments show that new algorithm improves the work efficiency and display effect of flight simulation system.

2013 Vol. 33 (4): 79-82 [Abstract] ( 1232 ) PDF (844 KB)   ( 2875 )
83 RESEARCH ON ENGINEERING APPROACH TO GENERALIZATION 
OF LAND-USE PARCELS
Chen Mengzhu, Cheng Xiong, Zhang Xinli, Gao Hui

On the basis of the morphological expansion and corrosion principle, we put forward a method and flowprocess in landuse parcels generalization which is suitable to fast engineering application, combining with the general law of map generalization and minimum cartographic area, distances between patches and width of the parcel on landuse map. A typical case study of the difficult part of long and narrow patches proves that it is efficient to obtain the generalization goal using this method.

2013 Vol. 33 (4): 83-87 [Abstract] ( 983 ) PDF (555 KB)   ( 3063 )
88 APPLICATION OF MINIMUM CLOSED LOOPS SEARCHING 
ALGORITHM IN DETECTING INSAR PHASE UNWRAPPING ERRORS
Chen Tao, Qin Tianyi, Chen Xiaosen, Wang Hua

Based on the Minimum Spanning Tree (MST) method, we improved the searching algorithm for minimum closed loops in consideration of multiple connected graphs. A tree and some redundant branches are built up according to the nodes and the length of edges. The minimum spanning condition was satisfied by sequentially selecting the redundant branch which can construct the minimum loop. The independent condition was satisfied by keeping onetoone correspondence between the redundant branch and minimum loop. Finally, we applied the algorithm to detect InSAR phase unwrapping errors which greatly improved the efficiency of InSAR data processing.

2013 Vol. 33 (4): 88-91 [Abstract] ( 1342 ) PDF (709 KB)   ( 2999 )
92 CONTAMINATION RATE ESTIMATION BASED ON ENTROPY
Zhou Fangbin,Zhu Jianjun,Chen Yongqi

An estimation method of contamination rate based on entropy was proposed. It is useful for gross error statistic to avoid limited error selection. Two models of data main distribution were suggested to investigate contamination rate and the estimation methods of contamination rate based on entropy were given out. A numerical simulation was performed to analyze the influence of entropy truncation error on data contamination rate estimation. It is less influence for entropy truncation error to contamination rate estimation based on entropy. When truncation error is 0.01, the variation of contamination rate estimate is only 1%. The examples show that the estimation method of contamination rate based on entropy is reliable and superior to the traditional estimation.

2013 Vol. 33 (4): 92-95 [Abstract] ( 1151 ) PDF (381 KB)   ( 3377 )
96 3D SPACE COORDINATE SYSTEM TRANSFORMATION CONSIDERING 
GEODETIC ELEVATION ERROR
Tao Yeqing,Zhang Sheng,Yang Juan

In the  transformation from national referenceellipsoidcentric coordinate to national geocentric coordinate, the  lack of precise geodetic elevation of control points in referenceellipsoidcentric coordinate makes the rectangular space coordinates of control points contain error. And this factor has an impact on final conversion accuracy. Up to late the 3D space coordinate model based on least squares has not taken into account the
 influence. In this paper,we discuss the method of 3D space coordinate transformation based on total least squares, besides, compare the methods of coordinate transformation based on total least squares and least squares used known data.The result shows that the accuracy of the former is better than the later.

2013 Vol. 33 (4): 96-99 [Abstract] ( 1135 ) PDF (387 KB)   ( 3352 )
100 INFLUENCE OF TROPOSPHERIC REFRACTION CORRECTIONS ON 
PRECISE POINT POSITIONING CONSIDERING VERTICAL DEFLECTION
Lou Nan, Cheng Guangyi, Zhang Jiandong, Zhu Xuan,Yu Liang

The altitude angle of satellite is analyzed, and the influence of vertical deflections on altitude angle of satellite and tropospheric refraction corrections for GPS surverying is researched. The coordinates of stations are calculated using precise point positioning mode. The result shows that the influence of vertical deflection on station coordinate cannot be ignored.

2013 Vol. 33 (4): 100-103 [Abstract] ( 1222 ) PDF (357 KB)   ( 2721 )
104 APPLICATION OF ROBUST ESTIMATION IN PRECISE POINT 
POSITIONING
Li Qiang, Peng Junhuan, Li Shuhui, Zhang Ke,Wang Hongyou

A new strategy derived from robust estimation to improve the convergence time of precise point positioning is presented, and the 24 1hour data are processed to test the strategy. The results show that robust estimation is effective to improve the convergence time of precise point positioning, it also shows the success rate of robust estimation is better than that of least squares. The positioning results show that robust estimation is significant to improve the positioning accuracy of small spans, and could reduce the affection of the observations which their ambiguities aren’t convergent effectively.

2013 Vol. 33 (4): 104-106 [Abstract] ( 1205 ) PDF (342 KB)   ( 2564 )
107 A COMBINED ARIMA AND ANN METHOD FOR PREDICTION OF 
SATELLITE CLOCK ERROR
Liu Jiye,Chen Xihong,Xue Lunsheng,Liu Qiang

Aiming at the poor performance of short term prediction of navigation satellite clock error, a variable weight combined ARIMA and ANN method is proposed, which combines the virtues of ARIMA and ANN. To improve the accuracy of prediction, an additional momentum term is used to modify the weight of the neural network and a sequence relative nearness degree is used to modify the weight of models. The clock data of 4 typical GPS satellites are chosen and respectively used in ARIMA, ANN and variable weight combination models to forecast short term clock error. The results show that the accuracy of variable weight combination model is superior to the other models, especially in the field of rubidium clock, the error of which is half of the other models.

2013 Vol. 33 (4): 107-111 [Abstract] ( 1121 ) PDF (1413 KB)   ( 2757 )
112 A NEW METHOD OF NAVIGATION SATELLITE CLOCK BIAS 
PREDICTION AND INTERPOLATION
Wang Yupu, Lü Zhiping, Chen Zhengsheng, Huang Lingyong

On the basis of quadratic polynomial, the model of leastsquares collocation to estimate satellite clock bias is established by considering the random part of satellite clock bias. To determine the covariance function of this model, the paper selects the empirical function and combines the experiments of clock bias data comparing to the covariance function fitting of leastsquares collocation, then obtains reasonable value ranges of the parameter for the model’s covariance function. Finally, the model is certified to have a good performance in the shortterm prediction of clock bias and can be also served as a new interpolation method by comparing with common algorithms of clock bias prediction and interpolation.

2013 Vol. 33 (4): 112-116 [Abstract] ( 1132 ) PDF (943 KB)   ( 2872 )
117 APPLICATION OF RESIDUAL ERROR FORECASTING SOFTWARE 
FOR GREY SYSTEM
Yan Ziping,Zhang Qingtao,Li Zhenhong,Ding Xuezhi

A forecasting software titled GMRCFS has been developed based on the GM(1,1) residual error model of grey system, and deformation of Geheyan dam has been predicted by five GPS monitoring sites on June 10 to November 28 in 1998. The results show that the GM(1,1) residual error model has high accuracy, it could satisfy the demand of dam deformation forecasting if a step size is chozen reasonably.

2013 Vol. 33 (4): 117-119 [Abstract] ( 1113 ) PDF (623 KB)   ( 2620 )
120 RESEARCH ON 3D TROPOSHPERIC DELAY TOMOGRAPHY BASED ON 
BACKPROJECTION METHOD
Zhao Qingzhi,Zhang Shubi

Tropospheric delay density is resolved with the groundbased GPS monitoring network data in USA solved by the GAMIT/GLOBK software based on tropospheric slant path total delay virtualized by backprojection method. Tropospheric delay 3D feature is analyzed by the method of tomography.The result shows that zenith total delay solved by two methods is small, the maximum error is less than 5 mm, and the mean square is 4.1 mm.

2013 Vol. 33 (4): 120-123 [Abstract] ( 1099 ) PDF (950 KB)   ( 2999 )
124
PS POINT CLOUD SEGMENTATION AND ORBITAL RAMP ESTIMATION
BASED ON DELAUNAY TRIANGULATION AND TARJAN’S ALGORITHM
PS POINT CLOUD SEGMENTATION AND ORBITAL RAMP ESTIMATION
BASED ON DELAUNAY TRIANGULATION AND TARJAN’S ALGORITHM
[J]. Journal of Geodesy and Geodynamics, 2013,33(4): 124-127>')" href="#">
Li Gang, Qiao Xuejun, Nie Zhaosheng, Jia Zhige

The PS point cloud segmentation and orbital ramp correction based on the Delaunay Triangulation and Tarjan’s algorithm was proposed in order to amend the estimation errors of orbital ramp correction during the PSInSAR processing. The PSInSAR results of Kashi prefecture recorded by the Envisat satellite of European Space Agency show that: Comparing with the traditional methods, this algorithm could eliminate the orbital errors effectively and avoid the errors caused by the notunicom unwrapping area. And the algorithm is applicable to the areas with continuous distribution of PS points in the entire images and could be coverd basically.

2013 Vol. 33 (4): 124-127 [Abstract] ( 1226 ) PDF (1557 KB)   ( 2805 )
128 PRECISION ASSESSMENT OF ZENITH TROPOSPHERIC DELAY 
CALCULATED FROM EGNOS MODEL OVER ASIAN AREA
Huang Liangke, Liu Lilong,Zhou Miao,Zhang Tengxu, Zheng Hao, Yao Chaolong

The tropospheric delay is a main error source for the global satellite navigation and positioning, and the EGNOS model can be used to calculate the zenith tropospheric delay.The Zenith Tropospheric Delay (ZTD) data observed from 48 International GNSS system (IGS) sites which distributed in Asian area are used to assess the effectiveness and accuracy of ZTD calculated from EGNOS model in 20092011, and the application of the EGNOS model is also analyzed in Asian area. The results show:1) relative to IGS observed ZTD, the bias and Root Mean Square(RMS) for ZTD calculated from the EGNOS model are -0.18 cm and 5.98 cm respectively in Asian area, and the bias and RMS are 0.81 cm and 6.13 cm respectively in China.2) The bias and RMS show a obvious seasonal variation. The bias generally shows the largest value in the summer and the smallest values in the autumn, while the RMS shows the largest value in the summer and the smallest values in the winter.3) The relation between the bias and the altitude or latitude is not obvious, but the RMS decreases with the increasing altitude or latitude, and the bias and RMS show a relative smaller valves in high latitude of the northern and western areas.4)The daily bias and RMS at low latitude of southern area and eastern area in the summer have a relatively larger variation.

2013 Vol. 33 (4): 128-132 [Abstract] ( 1232 ) PDF (1223 KB)   ( 2784 )
133 A NEW SELENOID MODEL AND REFERENCE TRIAXIAL LEVEL 
ELLIPSOID
Feng Hai, Li Jiancheng, Li Dawei, Liu Zhiyong

〗A new selenoid (lunar geoid) is derived using the lunar gravity model CEGM02 and topography model LRO_LTM02, which approximates the physical surface as closely as possible. The estimated gravity potential value of this selenoid is 2 822 327.8±16.2 m2/s2, denoted as W0 in usual. A triaxial level ellipsoid whose surface gravity potential equals W0 above is calculated and used as a reference ellipsoid, and its semimajor axis, polar flattening, equator flattening and longitude of semimajor axis are 1 737 462 m, 1/2 579, 1/6 863  and -76.8 ″, respectively. Based on this reference ellipsoid, the gravity decreases about 60×10-5ms-2  from the equator to the poles, while the variation along the equator is about 25×10-5ms-2. The selenoid undulations are in the range of -325.9 m to 389.1 m.

2013 Vol. 33 (4): 133-136 [Abstract] ( 1297 ) PDF (673 KB)   ( 2992 )
137 A MULTIPATH CORRECTION METHOD BASED ON WAVELET 
FILTERING AND PCA
Zhang Haonan,Kuang Cuilin, Lu Chenlong,Zhou Yuanhua

According to the noise characteristics, an integrated noise correction method based on wavelet filtering and the Principal Compoment Analysis (PCA) is proposed. The experiment data shows that the combined method is superior to a single filtering method, the former can effectively weaken the multipath effect and high frequency random noise.

2013 Vol. 33 (4): 137-141 [Abstract] ( 1300 ) PDF (818 KB)   ( 2495 )
142 A NEW ALGORITHM FOR DETERMINING SINGLE RECEIVER DCB
Xie Yibing, Chen Junping, Wu Jicang

Based on the variance components estimation, the receivers DCB and VTEC residual values are calculated by the pseudorange data with carrier phase smoothing and the vertical electronic content (VTEC) and the DCB of satellites. By using 35 IGS stations data, the DCB of 40 IGS receivers are estimated. The results show that the accuracy of DCB can be better than 1 nanosecond compared with the DCB provided by the IGS.

2013 Vol. 33 (4): 142-145 [Abstract] ( 1039 ) PDF (761 KB)   ( 3118 )
146 A METHOD FOR ESTABLISHING MEAN FREE-AIR GRAVITY 
ANOMALY BASED ON ISOSTATIC THEORY
Wang Wei, Li Shanshan, Ma Biao,Gao Xinbing

The method of establishing the mean freeair gravity anomaly reference field with rare gravity data has been studied based on the Airy and Heiskanen isostatic theory. The numerical model of the mean freeair gravity anomalies has been established using the regional highresolution topographic data; then for the problem that the systematic errors existed in the computational area, a few of gravimetric points have been chosen as constraint points in order to eliminate errors. Finally, the comparisons have been made among the gravity field model of EGM2008 and interpolation using separate points. As a result, the method could get better precision than two other methods as well as could reduce workloads in gravity measurement in the fields, the method is suitable for establishing the mean freeair gravity anomalies in difficult conditions.

2013 Vol. 33 (4): 146-150 [Abstract] ( 1102 ) PDF (1622 KB)   ( 2782 )
151 INSTRUMENT SITE CALIBRATION CAN NOT BE REPLACED 
BY DATA PROCESSING
Liu Xuyan

The paper analyzed the relative calibration and absolute calibration of four component borehole strain observation. By the theorem “sum of vertical components must be equal”, we can only obtain the ratio of site scale value of 3 sensors and the sensor which is as a constant element, but we cannot get site scale value, so it cannot solve relative calibration. By the relationship between tides and component strain observation value, the coupling coefficient can be calculated, but calibration of the elastic parameters cannot solve the problem of the absolute calibration of strain.

2013 Vol. 33 (4): 151-154 [Abstract] ( 1094 ) PDF (366 KB)   ( 2361 )
155 TEMPORAL AND SPATIAL DISTRIBUTION ANDYSIS ON 
INTERNATIONAL HIGHRATE GNSS DATA SHARING SERVICE
Gao Shuzhao,Chen Qiang

Data sharing services from six international research organizations are summarized with the geographical distribution maps of highrate sites drawn. And the temporal characteristics of observation data are analyzed. This can provide important data resource for seismic activity monitoring research. Finally, an example is illustrated to show the application of highrate GNSS sharing data in the seismic research.

2013 Vol. 33 (4): 155-159 [Abstract] ( 1163 ) PDF (1603 KB)   ( 4529 )
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