大地测量与地球动力学
 
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2009 Vol.29 Issue.4
Published 2009-09-26
地壳形变与地震
1 STUDY ON PRECURSORY STRAIN CHANGES OF WENCHUAN EARTHQUAKE WITH ORA METHOD
Qiu Zehua ;Zhou Longshou ;and Chi shunliang
Frequent pulses, whose period from minutes to hours, were recorded with the YRY4 strainmeter at Guza station before the Wenchuan earthquake in 2008.
Via highpass filtering, strong correlation between the recorded pulses and the main shock is revealed. In order to prove,an Overrun Rate Analysis (ORA) is carried out for a systematic and quantitative examination of the abnormal changes, based on three criteria with respect to the periods for before, during and after the main shock, respectively. The phenomenon does not seem to be close to the so called precursory longperiod wave preceding a macroquake but is similar to the acoustic emission prior to the fracture of rocks.
2009 Vol. 29 (4): 1-4 [Abstract] ( 2002 ) PDF (1937 KB)   ( 2616 )
5 DISCUSSION ABOUT INFLUENCE OF ITRF “FRAME DRIFT” ON GPS CONTINUOUS OBSERVATION
Yang Guohua ;Wang Cuizhi ;Yang Bo ;Zhang Fengshuang ;Liu Xia ;and Han Yueping
Taking GPS continuous observation of Tianjin station as example, the paper does a research and discussion on the influence of ‘frame drift’. Through comparison between the results of weakening and not weakening the influence of ‘frame drift’, we found that, after weakening, the white noise of observations is about 1/2-2/3 of that before weakening.Except for the white noise, the stochastic noise is also discovered as the important part of ‘frame drift’, and it can be weakened in the same processing as well.
2009 Vol. 29 (4): 5-9 [Abstract] ( 1845 ) PDF (2386 KB)   ( 3270 )
10 BASELINE VARIATION OF GPS CONTINUOUS SITESAND CURRENT ACTIVITY OF QINGHAITIBET BLOCK
Guo Liangqian;Hu Xinkang;Zhang Fengshuang;Chen Changyun;and Sun Dongying
On the basis of the GPS observations during 10 years, the variations of the baselines between adjacent GPS continuous sites in the QinghaiTibet block and the surrounding areas are calculated, and then the activities of largescale crustal blocks and tectonic zones are studied on the basis of obtained tendency and nonlinear variations. The NW ward baseline in the western part of the QinghaiTibet block shows a variation of extension and the crust displays a tensile change in the direction.The NE ward baseline in the eastern part shows a large convergent velocity, indicating that the crust contracts intensively in the direction. Before the West Kunlunshan mountain M8.1 earthquake and the Wenchuan M8.0 earthquake, the baselines showed obviously anomalous variations during a period of several months to more than a year, which reflects that the occurrence of large earthquake with shallow focus is associated with the intensification of largearea tectonic movement.
2009 Vol. 29 (4): 10-14 [Abstract] ( 1764 ) PDF (1481 KB)   ( 3011 )
15 RELATIVE MOTIONS OF BLOCKS IN CHINA CONTINENT AND THERE RELATIONS WITH STRONG SEISMIC ACTIVITY
Zhang Yuegang ;Zhang Jing ;and Wang Min
Rigid motion model of China continent blocks is established from several period GPS data, and the relative motions among the blocks in China continent is analyzed. Through analysis of the evolution of blocks’ motion, the variation that crustal deformation offset from background field is studied, and its influence on the seismic activity in China coontinent is also analyzed. The blocks in China continent move eastwards generally, and the rate is defferent from each other, in which the rate of Tibet block is the biggest, and it is gradually weaker towards north and east. Compared to western blocks, the directions of eastern blocks show a clockwise rotation. There is a dynamic diffrence between the blocks’ motion in defferent period. As the motion of one or two blocks shows relatively independence, the variation of block motion is not complately consistent.
2009 Vol. 29 (4): 15-20 [Abstract] ( 1825 ) PDF (2069 KB)   ( 3338 )
21 OBSERVATION OF TRAPPED WAVES IN EASTERN SEGMENT OF HOH SAI LAKE-MAQEN FAULT
Pan Jishun;Zhang Xiankang ;Yao Zhixiang ;and Liu Zhi
The observation of the faultzone trapped waves was conducted on some seismic line with dense receivers across Hoh Sai lakeMaqen fault. It is found that the faultzone trapped waves of long period and big amplitude will appear after S wave so long as the sources and observation points are located in or near the faultzone. The finite difference forward simulation also shows that the surface rupture width of the eastern segment of Hoh Sai lakeMaqen fault is 225 m while the fault width reduce to 175 m in the depth below 150 m.
2009 Vol. 29 (4): 21-25 [Abstract] ( 2218 ) PDF (3321 KB)   ( 3774 )
26 RESEARCH ON RELATIONSHIP BETWEEN TECTONIC STRESSFIELD AND STRONG SEISMIC ACTIVITY IN YUNNAN AREA
Li Yujiang ;Chen Lianwang ;Li Hong ;and Ye Jiyang
On the basis of the 3D velocity structure, the active tectonic blocks, the seismic activity, etc. in Yunnan area, a 3D finite element model is established. By determining the model’s boundary conditions based on the GPS data, the tectonic stress field in Yunnan area is simulated numerically. Through comparing the tectonic stress field with the M6 earthquake distribution in recent one hundred years, it is found that the stress transitional sections correspond well with the occured strong earthquake and three potential seismic risk regions are given.
2009 Vol. 29 (4): 26-29 [Abstract] ( 1841 ) PDF (2232 KB)   ( 3150 )
30 ON MOVEMENTS OF ACTIVE FAULTS BY ANT COLONY ALGORITHM INVERSION USING GRAVITY DATA
Liu Ning;Zhang Yongzhi;Wu Xiaoli;and Liu Feng
On the basis of the gravity change data of the Hexi area in 2002 to 2003 and 2004 to 2005 years, the movements of the HuangchengTaerzhuang fault were inverted by use of the ant colony algorithm(ACA).The inversion result shows that the ACA can be used for solving the 3D slipe rate of a fault effeciently,and the result is in basical accordance with the result obtained with geological method.Moreover,the result shows that the slipe rate of the HuangchengTaerzhuang fault appears spatially unevenness.
2009 Vol. 29 (4): 30-33 [Abstract] ( 1829 ) PDF (1482 KB)   ( 3077 )
34 RESEARCH ON HORIZONTAL CRUSTAL MOTION ANDSTRAIN FEATURES OF WEIHE BASIN WITH GPS DATA
Qu Wei;Zhang Qin ;Wang Qinling ;and　Lin Qing;
On the basis of the GPS data from 2001 to 2004,
the horizontal crustal motion features of the Weihe basin were analyzed.
The relations between earthquakes and the strain distribution features were also discussed.
The following results are obtained: 1)There is difference between the movements,relative to the stable Ordos block,on the eastern and western side of the Weihe basin,
among which the horizontal velocities of the GPS sites located at both sides of Bin CountyXi’anLantian which is in the middle of Weihe Basin are obviously bigger than that in other areas；2)Jingyang Xi’anXianyangLintong area of Guanzhong district is the maximum
zone of high shear strain and also has intensive isogram of high strain, which corresponds to small earthquakesprone areas, namely, TongchuanJingyangLintongWeinan region.
2009 Vol. 29 (4): 34-37 [Abstract] ( 1738 ) PDF (1640 KB)   ( 3823 )
38 CHARACTERISTICS OF LOCAL GRAVITY VARIATION BEFOREAND AFTER DINGYUAN ML4.7 EARTHQUAKE
Xu Rugang ;Zhang Yi ;Gu Chunlei ;Wang Lei ;Zhu Zhichun ;Sun Shaoan ;and Li Hui
By use of mobile gravity data in the northern area of Anhui province during 2005-2007, the dynamical gravity variation features before and after Dingyuan ML4.7 earthquake are analyzed. The results show that Dingyuan earthquake occurred in the
high gradient zone of gravity variation near the area with high negative gravity variation.Before the earthquake, the gravity values around epicenter decreased, at the same time the high gravity gradient belt came into being along active faults;after the earthquake, the gravity field takes on relax and resumption.The dynamic gravity variations clearly reflect the features of source precursor caused by stress field of seismic focus.
2009 Vol. 29 (4): 38-41 [Abstract] ( 2279 ) PDF (2384 KB)   ( 2584 )
42 FOCAL MECHANISM SOLUTIONS OF AFTERSHOCKS OF JIUJIANGRUICHANG EARTHQUAKE
Zeng Wenjing;Zhao Aiping;Tang lanrong;Li Chuanjiang;and Zhou Shuiling
With the point source dislocation model in layered medium and using the records of mobile seismic network,we calculated the focal mechanism solutions of 112 ML≥1.5 aftershocks of the JiujiangRuichang earthquake. By analyzing the results,the conclusions are obtained:1) The predominant rupture strikes of the JiujiangRuichang earthquake aftershocks are NNW and NEE, its predominant dip angle is between 50 and 60°,and its predominant slip angle is between -60 and -100°;2)The pressure axis of epicentre stress field is distributed in the near diretion of EW,and its tensile axis is distributed in the near diretion of NS. The predominant orientation of these solutions is close to the character of tectonic stress field in north Jiangxi.
2009 Vol. 29 (4): 42-47 [Abstract] ( 1786 ) PDF (948 KB)   ( 3067 )
48 ANALYSIS OF TIDAL DATA BEFORE WENCHUAN Ms8.0 EARTHQUAKE
Chen Zhiyao;Lu Pinji;Li Zhengyuan ;Zhao Bin;and Lin Suiping
The data for 5 years observed at 9 fixed crustal deformation stations were used to calculate the tidal factor and phase delay series before the Wenchuan Ms8.0 earthquake.It is shown that at 7 stations there were abnomal changes before the earthquake. The nearer
the station located to epicenteris, the greater of the abnormal signal.However the abnormal signal from the two stations were not obvious
before the earthquak, one was Maoxian which is 100 km away from the earthquake and another was Kangding which is 200 km away from the earthquake. This fully demonstrates the complexity of earthquake precursors.
2009 Vol. 29 (4): 48-50 [Abstract] ( 1994 ) PDF (2020 KB)   ( 3929 )
51 ANALYSIS OF GEOTHERMAL COMPARATIVE OBSERVATION AT SHAHE SEISMOSTATION
He Anhua ;Zhao Gang Xue Na ;Wang Jun ;Guo Miaoxi ;Guo Bailin ;and Fu Zizhong
By use of curve fitting and discretigation analyzing the data of two digital thermometer placed in the same depth at Shahe seismostation,we can conclude that the data are reliable, their change trends keep consistent, the temperature difference from each other is only 0.007 5℃,almost constant and really reflect the downhole temperature variation. The article summarizes the concrete operation method for installing two sets of digital thermometers for comparative observation and solving the difficulty of excluding the instrument trouble when appear abnormal data.
2009 Vol. 29 (4): 51-54 [Abstract] ( 1836 ) PDF (2142 KB)   ( 2893 )
55 CHANGE OF MEAN SEA LEVEL OF LOW-FREQUENCY ON EAST CHINA SEA AND ITS RELATION WITH ENSO
Liu Xueyuan;Liu Yuguang;Guo Lin;and Gu Yanzhen
On the basis of the sea level anomalies (SLA) altimeter data provided by CNES,the mean sea level change on the East China Sea was investigated. In recent 14 years, the rising rates have reached to 0.412 cm/a，0.292cm/a respectively in the northern part and southern part of East China Sea separated by 30°N obviously,they are different. Correlative analysis shows that low frequency components of SLA have good but opposite response to that SOI and zonal wind stress anomalies, over the northern part and southern part of East China Sea. It is obvious that the sea level variation is closely related to SOI and zonal wind stress anomaly and it indicats that sea level in the East China Sea is dominated by El Nio, as well as zonal wind stress.There is also a good relationship between SOI and the wind field over the East China Sea, of which the low frequency components are corresponding to ENSO. By using correlative analysis between SLA and wind stress anomalies u component in the new coordinate system, it is found that the direction of wind stress most strongly affecting the sea level is 70 degrees and 23 degrees south of east separately, over the northern part and southern part of East China Sea. The divergence zone affects the wind field of the East China Sea strongly by atmospheric circulation, and that makes SLA and wind stress anomalies response differently between the northern part and southern part of the East China Sea. Based on the analysis above, a conclusion could be drawn that zonal wind stress affects the sea level significantly, indicating that ENSO impacts on wind filed of the East China Sea by means of atmospheric circulation, hence affecting the sea level. To sum up, ENSO and wind stress contribute to the sea level change over the East china Sea. In detail, ENSO impacts on wind filed of the East China Sea, hence affecting the interannual change of sea level, and sea surface wind responses well to ENSO, showing that ENSO could affect the sea level of the East China Sea, through mechanism of wind stress.
2009 Vol. 29 (4): 55-63 [Abstract] ( 2296 ) PDF (5952 KB)   ( 3016 )
64 ON SEA LEVEL ANOMALIES OF LOW FREQUENCY SIGNALS　IN TROPICAL PACIFIC OCEAN
Guo Lin;Liu Yuguang;Liu Xueyuan;Lv Xuezhu ;and Li Yifei
On the basis of the altimeter data between October 1992 and May 2007, the interannual variations of sea level anomalies (SLA) of the tropical Pacific Ocean are investigated. It is found that:1) Sea level anomalies during the period of 24-42 months (SLA_2442) are associated with the interannual variations of ENSO; 2) SLA_2442 circuit exists not only during strong ENSO terms like the El Nio of 1997/1998, but also with weak El Nio events, such as the El Nio of 1994/1995, and even in normal years; 3) Each circuit of SLA_2442 signals is cyclonic in both of the north and south hemispheres, whose pattern looks like an “O”, but not symmetrical. In addition, the circuit pathways are near 0°, 9.86°N and 8°S,respectively.
2009 Vol. 29 (4): 64-69 [Abstract] ( 1824 ) PDF (2632 KB)   ( 3009 )
70 RESEARCH ON INVERSION OF SEAFLOOR TOPOGRAPHYOF CHINA SEA AND ITS ADJACENT AREAS FROM SATELLITE ALTIMETRIC DATA
Li Dawei;Li Jiancheng;Feng Hai;and Jiang Tao
On the basis of linear relation between gravity anomaly and seafloor topography, the 2′×2′ bathymetry model in China sea and its adjacent areas would be calculated from the satellite altimeterderived gravity anomalies and with ETOPO2v2 model. On the other hand, the calculated result is compared with the ETOPO2v2 model and shipboard depth, and then the following conclusion can be drawn that the bathymetry model calculated by gravity anomaly can reflect the characters of suboceanic structure exactly in China sea and adjacent Areas.
2009 Vol. 29 (4): 70-73 [Abstract] ( 2053 ) PDF (2990 KB)   ( 3445 )
理论方法研究
74 METHODS FOR DETERMINING COVARIANCE FUNCTION OFCHINESE HORIZONTAL MOVEMENT OF MAINLAND
Chai Hongzhou;Cui Yue ;Zhai Tianzeng ;and Ming Feng
For determining the covariance function in the collocation model for analyzing crustal deformation a new method considering the physical characters and spacial attribute of crustal movement is proposed, into which the calculated deformation value is introduced and
centralized and the determination is made in different regions and different directions. Using the observed data and combining the robase estimation we have established the more representative covariance function model of the horizontal movement of the main blocks of China continent.By use of this model the calculated results can be interpreted more reasonably.
2009 Vol. 29 (4): 74-78 [Abstract] ( 1872 ) PDF (929 KB)   ( 2992 )
79 DE-NOISING OF GPS OBSERVATIONS WITH WAVELET THRESHOLD METHOD
Wu Jizhong;
Wavelet transform is usually used to reduce the high frequency noise of carrier phase GPS double differences observation. The computation outputs with soft thresholding and hard thresholding as well as several threshold selection rules are compared. The experiments indicate that ambiguity solutions become more reliable and the coordinates more precise after wavelet threshold denoising,while different threshold selection rules generate different results. In general, the soft thresholding with the universal threshold provides the best results
2009 Vol. 29 (4): 79-82 [Abstract] ( 1938 ) PDF (1960 KB)   ( 3730 )
83 DETECTING CYCLE SLLIPS IN GPS SINGLE FREQUENCY CARRIER PHASE USING AN ADAPTIVE FILTER
Cao Yizhi ;Sui Lifen ;and Wang Wei
Using a twostage adaptive filter with GPS Doppler measurments to estimate L1 carrier phase, and then
the whitening residuals of L1 carrier phase can be obtained comparing it with the actual carrier phase measuments,and considering time correlation of highrate GPS carrier phase measuments error.Finally,by using the whitening residuals the cycle slips in GPS single frequency carrier phase will be detected and repaired. The method is fit for highrate single frequency GPS data. A test using 1 Hz dynamic GPS data reveals that it can detect very small cycle slips.
2009 Vol. 29 (4): 83-87 [Abstract] ( 1982 ) PDF (765 KB)   ( 3100 )
88 APPLICATION OF ACCELERATION DATA TO PRECISE DYNAMIC ORBIT DETERMINATION OF EARTH ORBIT SATELLITE
Kuang Cuilin
The variation of perturbation forces and the complexity of special flying environments of low earth orbit satellites make traditional dynamics orbit determination method can not be competent for cmlevel accuracy. It studies the application of acceleration data as a substitutive method for nonconservative perturbation force to dynamic orbit determination.Experimental results for gravity satellite CHAMP and GRACE show that cmlevel orbit accuracy can be reached by using acceleration observation. The accuracy is the same as compared with the experienced force compensation model method and better than the traditional method which deals with all force by modeling.
2009 Vol. 29 (4): 88-92 [Abstract] ( 2099 ) PDF (1630 KB)   ( 3411 )
93 RESEACH ON APPLICATION OF SEMIPARAMETRIC MODEL IN SYSTEMATIC ERROR
Liu Shuang;Zhang Songlin;and Tong Xiaohua
In order to explain the application of the semiparametric model in surveying data processing,the effects of the systematic errors’ characteristics on the quality of the results were analyzed, the conditions for applying semiparametric model to handle systematic errors were discussed,and a set of simulated examples based on semiparametric model were designed.The simulated results show that if the magnitude of systematic errors is not significantly bigger than random errors,the frequency of systematic errors is not very high and has no relationship with that of the observations,the semiparametric model can be used for processing the systematic errors and improve the accuracy of data processing.
2009 Vol. 29 (4): 93-96 [Abstract] ( 2028 ) PDF (1751 KB)   ( 3123 )
97 FILTERING ALGORITHM FOR NON-GROUND POINT FROM AIRBORNE LASER SCANNER DATA
He Zhengbin;and Tian Yongrui
The point clouds filtering based on scanning lines, which does not need to establish complex data structure, is not only simple in computation structure but also efficient in computation time. It is suitable for departing the terrain points and non-terrain points from the point clouds. In order to leave out the pre-processing before the filtering, a modified filtering of point clouds based on so called “pseudo scanning lines” by slope is proposed in this paper. The modified algorithm not only has the advantages of the point clouds filtering based on scanning lines, but also makes sure that the starting reference point for judging the terrain information is a real terrain point. In addition, a curve fitting method with moving window is used to follow the modified point clouds filtering in order to avoid the difference of neighboring pseudo scanning lines for the same terrain. An actual example shows that the modified point clouds filtering with the corresponding curve fitting is efficient.
2009 Vol. 29 (4): 97-101 [Abstract] ( 1854 ) PDF (4275 KB)   ( 3619 )
102 SPHERE TARGET FIXING OF POINT CLOUD DATA BASED ON TLS
Lu Tieding;Zhou Shijian;Zhang Liting ;and Guan Yunlan
In terrestrial laser scanning, sphere target is an important accessory. With it, multiple point clouds data obtained form different views can be transformed into the same coordinate system frame. In order to complete the task mentioned above, determination of sphere target centre is a key. The common method to locating sphere center coordinate is least square. A new method for determining sphere target centre by total least squares is presented.On the basis of this model, the errors and the coefficient matrix can be corrected at the same time. Experiments using simulation data and real data were conducted. From the real point clouds results,it is shown that the proposed method is effective.
2009 Vol. 29 (4): 102-105 [Abstract] ( 1969 ) PDF (1771 KB)   ( 3451 )
106 IMPROVING POINT POSITIONING ACCURACY USING GPS CARRIER SMOOTHED PSEUDORANGE
Zhang Chengjun;Yang Li;and Chen Jun
The principle and data preprocessing of carrier smoothed pseudorange are discussed and the method which can improve the positioning accuracy and its flow are given.With this method two computation examples are made.
The results show that: 1)the accuracy can be improved efficiently by using smoothed C1 and P2 pseudorange in static data processing, the accuracy can reach 1 m if the time is long and can attain 0.5 m if the precise ephemeris is taken; 2)the accuracy can be boost hardly by using smoothed P1 and P2 pseudorange, but the accuracy can be improved from 0.6 m to 0.3 m if the time is long enough and the precise ephemeris is used; 3)most epochs can reach to the accuracy of 2 m precision in kinematic positions if the smoothed code and precise ephemeris are utilized.
2009 Vol. 29 (4): 106-110 [Abstract] ( 1929 ) PDF (1637 KB)   ( 3509 )
111 RESEARCH ON CLOCK ERROR PREDICTION FOR ATOMIC CLOCKSLOADED ON GPS BLOCK IIR(M) SATELLITE CLOCKS
Dai Wei;Jiao Wenhai ;Li Weipeng ;and Jia Xiaolin
Which models can be used to predict optimum GPS Block IIR(M) satellite clock errors were researched in the case of few surveying data.The research shows that the accuracy for predicting in one day is a 1 ns and it in ten days is 10 ns with the GM(1,1)AR(p) compound model. The prediction results with better than the results with quadratic polynomial model and GM(1,1) model and the accuracy is better than that from IGS(the International GPS Service for Geodynamics) of the accuracy of 7 ns.
Because the atomic clocks of COMPASS satellite navigational system are similar as these satellite atomic clocks, the accuracy can be assured using the GM(1,1)AR(p) compound model in COMPASS satellite clocks error prediction.
2009 Vol. 29 (4): 111-115 [Abstract] ( 2079 ) PDF (920 KB)   ( 3237 )
116 A NEW ESTIMATION METHOD FOR UNCERTAINTY OF CIRCULAR MARK LOCATION OPERATOR
Yan Lili;Gao Jingxiang;and Sun Jiuyun;
A new center positioning algorithm of circular mark was put forward,which can fit the ellipse parameters by nonlinear least squares. It improved the ellipse edge detection method in the subpixel positioning algorithm.

Moreover the estimating formula for mark location uncertainty was derived, and confidence interval in a certain confidence level was calculated by use of the Monte Carlo integration. An example certificates that the new location algorithm can achieve about 0.02 pixel positioning accuracy which rises nearly 10 times than that with the sub-pixel positioning operator when the photogrammetric scale is 1:75.
2009 Vol. 29 (4): 116-119 [Abstract] ( 1723 ) PDF (1002 KB)   ( 3487 )
120 ON KEY TECHNIQUES OF OPEN WEBGIS BASED ON GML SPATIAL DATABASE
Lan Xiaoji and Han Linqin
Achieving spatial data interoperability and services sharing has always been a goal of open WebGIS.In this regard,we suggest that GML can be used for spatial data encoding, and in order to achieve data interoperability the documents of GML are stored in GML spatial database.The technique of Web services can be used to deal with the problems of function interoperability.Finally,the GML documents
can be tranformed into SVG documents by XSLT, so the spatial data can be displayed on the screen.The system from data source to client display are all based on open standards specification,so a completely open system will be achieved.
2009 Vol. 29 (4): 120-123 [Abstract] ( 1887 ) PDF (595 KB)   ( 2724 )
124 APPLICATION OF BP NEURAL NETWORK BASED ON KALMAN FILTERING TO DAM DEFORMATION PREDICTION
Li Jiebin;and Kong Lingjie;
A new dam deformation perdition model of BP neural network based on Kalman filtering are put forward. The filtered sample data is used for BP training, it makes the network have dynamic properties and reduces the possibility of the local minimum value of Neural network. The precision and generalization ability of BP based on Kalman filtering are higher than those of the traditional BP neural network. Through the example it is proved that the new algorithm is of high accuracy and generalization ability in the data processing.
2009 Vol. 29 (4): 124-126 [Abstract] ( 1754 ) PDF (698 KB)   ( 3176 )
127 LANDSLIDE DEFORMATION PREDICTION BASED ON WAVELETANALYSIS AND LEAST SQUARE SUPPORT VECTOR MACHINE
Li Xiao ;and Xu Jinjun
A novel model based on wavelet analysis and Least Square Support Vector Machine(LSSVM) for landslide deformation prediction is presented. Firstly,in the view of timefrequency analysis,through the wavelet transform,deformation time series is decomposed into
components of different frequency and then the reconstructed approximate series and detailed series were predicted respectively by using LSSVM and the results were composed finally. The experimental results indicates that this prediction model has advantage over GM(1,1) ,AR and simple LSSVM as it has higher prediction accuracy and is applicable to predicting landslide deformation.
2009 Vol. 29 (4): 127-130 [Abstract] ( 1989 ) PDF (808 KB)   ( 3225 )
131 APLICATION OF HILBERT-HUANG TRANSFORM IN ANALYSIS OF EARTH TIDE DEFORMATION
Chen Tao ;Li Zhengyuan ;Chen Zhiyao ;Lv Pinji ;Zhao Bin ;and Lin Suiping
Used the tilt tidal data is processing with Hilbert-Huang(HHT).The key strongpoints of this method are that through the empirical mode decomposition (EMD), the signal is decomposed into a series of intrinsic mode function (IMF), and then the Hilbert spectrum in threedimensional timefrequency space is obtained.
2009 Vol. 29 (4): 131-134 [Abstract] ( 2028 ) PDF (3541 KB)   ( 3244 )
135 APPLICATION OF TWO PREDICTION MODELS IN GRID COORDINATE TRANSFORMATION
Guo Chong;Lu Zhiping ;Yu Xingchao ;and Xu Jigang
As China Geodetic Coordinate System 2000(CGCS2000) starts being used,the coordinate of surveying and mapping products need to be transformed and the method of coordinate transformation with high accuracy also need to be studied. Large residuals still remain after the transition by use of Bursa model from the astrogeodetic network of our country to highprecision geocentric coordinate system. In order to improve transformation accuracy,grid coordinate transformation is used to fit residuals further, in which covariance function and multiquadric function prediction model are respectively adopted to predict the coordinate correction of grid node. The experiment shows that the accuracies of these grid coordinate transformations on the two above prediction models are similar, so the two models are able to fit remaining residuals effectively. The residuals which remain after the whole transformation are in a low level and the high transformation accuracy is achieved.
2009 Vol. 29 (4): 135-139 [Abstract] ( 1897 ) PDF (475 KB)   ( 2947 )
140 WAVELET ANALYSIS OF J2 TIME SERIES OF GRACE AND SLR
Zhu Guangbin;Li Jiancheng ;Wen Hanjiang ;and Ding Jian

By use of wavelet power spectrum analysis and discrete wavelet transform, the periods and characteristics of J

2 time series of GRACE timevariable gravity models from CNES/GRGS、CSR、GFZ are analyzed and extracted, and then they are compared with the corresponding results of

J2 time series from SLR tracking data. The resalt shows that, the seasonal variation of J2 time series from SLR is clearer than that from GRACE. In addition,the signal for 161 days is mexed into GRACE J2 time series,which is caused by ocean tide model error in the S2 solar tide
2009 Vol. 29 (4): 140-143 [Abstract] ( 2074 ) PDF (3557 KB)   ( 3122 )
观测技术
144 DEVELOPMENT OF ULTRASHORT BASELINE EXTENSOMETER
Li Jiaming;Yao Zhigui;Zhang Weihua;and Mei Jianchang;
The design idea, the overall structure and the principle of operation of main components of extensometer of USBE1type and the test at stations are introduced. Test results show that thanks to the development of a sealing structure of highprecision capacitance sensor for
microdisplacement the length of instrument baseline can be shortened greatly for example,to not more than 1 m and it
can record the clear response to the solid tides, so can meet the small space and requirement for earthquake emergency.
2009 Vol. 29 (4): 144-147 [Abstract] ( 1965 ) PDF (931 KB)   ( 3889 )
148 PRECISE MEASUREMENT AND 3-D SURFACERECONSTRUCTION OF DEFORMATION STRUCTURE OF BRIDGE
Liao Zhongping ;Shen Yunzhong ;Zhou Zebo and Cai Shiyi

According to limited discrete datum points, a surface fitting method based on Matlab 6.5 for the deformation body is put forward. The steps of this method are, first, applying Delaunay triangulation on the irregular data, then, finding the nearest triangle of every interpolation points (

Xi,Yi) and interpolating this surface at the points to produce Zi based on the theory and method of trianglebased cubic interpolation. The results indicate that with this method
the 3D surface of the deformation body can be reconstructed, and the fitting surface is smooth.
2009 Vol. 29 (4): 148-151 [Abstract] ( 1794 ) PDF (3067 KB)   ( 3225 )
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