Home Table of Contents
29 August 2012, Volume 32 Issue 4
-
Select all|
-
. 2012, 32(4): 1-4.On the basis of vertical deformation rate and the activities rate of main fault zone which calculated from leveling data during 2000-2008, the vertical movement character of crustal blocks and the activity of main fault zone in BeijingTianjinTangshan area were studied. There was a rising vertical deformation in the north and a declining one in the south of BeijingTianjinTangshan area in past ten years. These vertical deformation roughly matched the topography and the landform, it reflected that the tectonic activities was a kind of inheritable movement. Most of the blocks had tilting activities.The activities of main fault were different, some of them were normal faulting activities, some of them were reverse faulting activities, some of them were turn twitching activities at vertical plane.The vertical activity rate of fault zone in BeijingTianjinTangshan area were between 1.00-2.00 mm/a.
-
. 2012, 32(4): 5-9.A part of the aftershocks of Yushu earthquake occurred from April 14 to December 31, 2010, were relocated by means of the double difference algorithm. These following conclusions can be obtained from the results. The area changing of stress growth led to aftershocks distribution shifting over time. The aftershock distribution presents spatial inhomogeneity. On both sides of Longbao, the intensity,width and the focal depth of the aftershocks are different. The seismogenic fault of aftershocks of Yushu earthquakes is the northern branch of Garzê-Yushu fault zone, i.e. YushuLongbao fault, which dips to northeast with high-angle left-lateral strike-slip.
To the northwest of Longbao town, the intensively distributed aftershock group is not only due to Yushu-Longbao fault zone, the more important seismogenesis is that the northwest “weak plane” is nearly vertical to the fault. -
. 2012, 32(4): 10-14.Several issues concerning the problrms and their concrete solutions that need to be solved in the application of elevation component time series of GNSS continuous operation station coordinates in vertical crustal movement studying are introduced.
-
. 2012, 32(4): 15-19.The reference station selecting during the earthquake is very important for the differential positioning software like TRACK in GAMIT/GLOBK. Some comparisons and analysis about Wenchuan earthquake are done, then we conclude that the for reference station select is most important.In the selection,the observations should be of high quality, the multipath effect should be less than 0.2 m
and the distance between rover station and reference station should be more than the product of the velocity of seismic wave propagation multiple by the lasing time. Compared with two undifferenced software GIPSY and PANDA, the results with this method are reliable. -
. 2012, 32(4): 20-24.The ground vertical deformation fields during the two times of huge deformation anomaly are figured out by DInSAR technique,along with the results of highdensity electric exploration around No BM3 benchmark, we drew several conclusions. Firstly, the InSARderived deformation fields indicate there is no continuous deformation anomaly that is related to the fault strike. In another word, the anomaly only showed in a local small area.
The other fact is that the No BM3 benchmark was built on the Holocene secondary loess, with the subsidence velocity of 5.11mm/a which is four times of the No BM4. And the anomaly time is consistent with that of the tomb construction.
Secondly, the anomaly at No BM3 benchmark should be related to the newly made tomb. The tomb construction may break the impermeable layer, which created a conduit between ground surface and the deepth. Thus, the No BM3 benchmark showed a rapid subsidence during the irrigation season when the subsurface erosion action made upper soil loose. -
. 2012, 32(4): 25-28.The measurements of FG5/232 absolute gravimeter in the course of the third European Comparison of Absolute Gravimeters in Walfdange, Luxembourg (ECAG-2011) are reported. The results showed that the standard deviation of the FG5/232’s results is less than 2.5×10 -8 ms -2, and it is consistent with others.
-
. 2012, 32(4): 29-32.On the basis of geological tectonic background and borehole structure, the relation between the characteristic difference of earth tide of well water level and physical parameters of confined aquifers at 8 stations of the ground water monitoring well network in the Three Gorges was analysised.The following conclutions are drawn that the earth tide of well water level varies inversely as the parameters of confined aquifers, with the porosity of the aquifer being constant;The earth tide of well water level varies inversely as porosity of the aquifer, with the the parameters of confined aquifers being constant, in addition,it was related to coefficient of transmissibility of confined aquifers,fault type,distance between well point and fault.
-
. 2012, 32(4): 33-36.On the basis of the “digital seismic network engineering” GPS monitoring results, and combined with regional tectonic features,
the 2D finite element model of the Weihe basin central region is built. According to the above, the present crustal deformationstrain distribution characteristics of the studied area are obtained. The results show that the Xi’anXianyang area is of significantly high value of the surface expansion and mainly tensile strain within the area, the value respectively reaches more than 2.0×10 -6 /a and 3.5×10 -6 /a. Thus
the present crustal tensile tectonic activity of Xi’anXianyang area is strong. -
. 2012, 32(4): 37-40.The observed data of 363 wells belong to China water level net for earthquake monitoring are collected and analyzed one by one. 9 parameters determinated by the day average value fitting,NAKAI fitting and monthly tidal factor are used to quantify the observed data.
On the basis of these results, the general standard parameters of the observation of these water wells are given. The five levels (A, B, C, D, and E) are defined according to the statistic results. The estimation results for each well are also calculated. The results could be referred by construction of well water level and the users of the data. -
. 2012, 32(4): 41-45.Through analyzing deformation data in Shanxi province, perturbations frequently appeared before M≥4 earthquake in range of 400 km or M≥5 earthquake in range of 500 km. It is shown in two aspects: 1)response of vertical pendulum in Hanzhong
seismostation, water tube tiltmeter at Qianxian station and Xi’an station, vertical pendulum at Ningshan station to large aftershocks of Wenchuan Ms8.0 earthquake, 2)response of vertical pendulum at Qianxian station to Hejing Ms4.8 earthquake. -
. 2012, 32(4): 46-50.On the basis of analysis of the tectonic landform and geologic features and TL dating,as well as drainage offset, we can draw some conclusions as follows.The Fangxian segment of Qingfeng fault was predominantly active in the Early Quaternary and weakly active in the Late one，and TL dating results range from 5×10 4 a to 7×104 a. The segment sufferred from two regime different tectonic movement,which is characterized by thrusting movement in the Early Quaternary and normal faulting and left-lateral slip movement in the Late Quaternary. Furthermore,the moving segment dislocated the branch drainage of the Malan river,with an average displacement of 1.7 km.The leftlateral movement dominates the development and evolution of Fangxian basin.
-
. 2012, 32(4): 51-56.In order to eliminate the effect from the topside ionosphere above LEO, it is necessary to retrieve electron density profiles based on the calibrated TEC below LEO, which introduces the approximation that the LEO and GPS orbit are close to being coplanar. In this paper, firstly an improved technique is proposed to eliminate this approximate error based on the noncalibrated TEC, and then the technique is applied in the inversion of simulated data and real observation data respectively. The results show that:1) whether the simulated data or real observation data are used, the inversion results derived from the noncalibrated TEC are better than those derived from the calibrated TEC technique, especially it is more obvious for low LEO altitudes;2) based on the above data, some serious errors occur while the electron density profiles are retrieved from the calibrated TEC, on the contrary, the inversion results derived from noncalibrated TEC are reasonable.
-
. 2012, 32(4): 57-60.By using the undifferenced ionospherefree model,the realtime satellite clock is estimated based on regional GPS continuously operating reference stations (CORS) data and IGU predicted orbit and then the realtime clock is respective compared with IGS final product and applied to the realtime PPP. The experimental results show that the accuracy between the estimate clock bias and IGS final product is better than ±0.2 ns, the kinematical accuracy of PPP is better than ±1 cm in horizontal direction, ±2 cm in the vertical direction.
-
. 2012, 32(4): 61-66.The data of Shanxi region CORS nearly two years are processed and then Shanxi CORS sites coordinates time series can be abtained subsequently.For the work,the CATS software is used to analyzed the noise characteristics of sites coordinates time series with Maximum Likelihood Estimation(MLE) and following useful conclusions are drawn.
Firstly，there are not only white noise but also colored noise in CORS coordinates time series.Secondly，the noise model in the directions N, E, U of CORS coordinates time series is not identical. In the N, E direction,the “WN + FN” noise model is oplimum and the “WN + FN + RWN” noise model in the U direction. Finally, when CORS coordinates time series are used to fit velocity, not only white noise but also colored noise should be considered for more correct relocity valuations. -
. 2012, 32(4): 67-70.Highland lakes have complex terrain features. During engineering survey and research trials, due to natural conditions, capital and human resource constraints, when a fixedpoint sampling is needed on the lake surface,it is difficult with the conventional measurement methods to achieve accurate depth and the horizontal distance. Taking the mapping process of 8 m isobath near Yangzonghai lake
gushing point as an example, a new simple method is suitable to the lake isobath and surface horizontal distance measurement is put forward and analyzed. The new method has great reference value for nonmapping professionals to map lake isobath lines and lake surface horizontal distance.Highland lakes have complex terrain features. During engineering survey and research trials, due to natural conditions, capital and human resource constraints, when a fixedpoint sampling is needed on the lake surface,it is difficult with the conventional measurement methods to achieve accurate depth and the horizontal distance. Taking the mapping process of 8 m isobath near Yangzonghai lake
gushing point as an example, a new simple method is suitable to the lake isobath and surface horizontal distance measurement is put forward and analyzed. The new method has great reference value for nonmapping professionals to map lake isobath lines and lake surface horizontal distance. -
. 2012, 32(4): 71-75.According to the respective characteristics of polar motion and length of day, combining LS and AR model, a suitable prediction model for the Earth Rotation Parameter (ERP) was builded. In order to reduce the strong correlation, the difference before establishing AR model was down and ERP 1-10 days were predicted. The results show that the prediction accuracy has reached an international leading level.
-
. 2012, 32(4): 76-78.GPS Double-difference observations were decomposed through wavelet analytical method and the areas where biggish perturbation will occur were determined by the reconstructed high frequency signal.According to the theory and method of Kalman filtering ,then the observations of iffy areas were detected and corrected for cycle slip.The results indicate this method can repair small cycle slip primely,and has a good result for continuous cycle slips.
-
. 2012, 32(4): 79-82.Taking the software of GAMIT/GLOBK as an example, this paper discusses and deduces the principle and implementation process of datum definition with HELMERT transformation, and poses the concept of system constraints, then verifies these conclusion using field data.
-
. 2012, 32(4): 83-86.Because the transfer function between the geodetic coordinate system and the Cartesian coordinate system is a multiimplicit function, whose explicit expression is more complex and the unit of the parameters is not uniform in the GNSS positional error conversion. This paper uniformly converts the angle error to length error in geodetic coordinate system by radius of parallel circle and curvature radius of meridian, and the transformation matrix has been derived. The results show that the matrix is not only simple in form but also an orthogonal matrix.
-
. 2012, 32(4): 87-89.A method of gridbased DEM construction in terms of Coons patch has been presented. Two examples including a numerical test and a real-world example were employed to comparatively analyze the simulation errors of Coons patch and the classical interpolation methods including IDW, SPLINE and KRIGING. Gaussian synthetic surfaces with various terrain complexity controlled by coefficient parameters were simulated and the results indicated that with the increase of terrain complexity, the simulation errors of all the methods will increase as well. The Coons patch is much more accurate than the classical methods. The real-world example was used to test the effect of sampling interval on the simulation accuracies of all the interpolators. The results indicate that sampling interval has a negative effect on the simulation accuracy. However, the Coons patch is more accurate than the classical interpolation methods regardless of sampling interval. In terms of simulation accuracy and computing speed, Coons patch can be considered as an alternative method for DEM construction.
-
. 2012, 32(4): 90-93.The author analyzes the different remote sensing data source in the interpretation of fault structures, by using ETM+ image,SPOT5 image and DEM data.
Remote sensing data from different sources for the fault structure interpretation results was carried out and verified. The results show that ETM + image is suitable to extract the fault structure with tonal or ribbon anomaly, SPOT5 images to the fault structure with linear
morphological characteristics.DEM data is suitable to extract other remote sensing image with geomorphology / microgeomorphology information and buried fault. -
. 2012, 32(4): 94-98.The authors found difference images based on the contrast can stand out changed information better
using texture features extraction of SAR images based on gray level coocurrence matrix, to analyze the principle of the GLCM, feature vectors and the characteristic parameters determined,logarithmic ratio operator constructed difference images,
we made the difference images based on the contrast as the base of change detection. As the images in accordance with the Gaussian mixture model,
so we estimate the parameters of the Gaussian mixture model with expectation maximum (EM) algorithm, and then use Bayesian minimum error rate to extract change information,finally compare it with the change detection results based on the pixel grayscale value. The test proved that the change detection method based on GLCM texture features has the lower false alarm rate, the lower missing rate, the smaller overall error and better detection effect. -
. 2012, 32(4): 99-102.The variation function of Geostatistics is introduced to analyze the characteristics of GPS deformation monitoring sequence. This paper not only simulates the periodical deformation sequence by use of the 3D dynamic simulter for deformation vector and analyzes the fitting data by use of the vriation model of noisy period sequence,but also simulates the variation function of the measured sequence.
The results of the experiment indicate that the dynamic deformation sequence of high building measured by GPS has Gauss and autocorrelation characteristics which can serve to further analysis and modeling. -
. 2012, 32(4): 103-105.In a mining area, the data of normal height and geodetic height are used to build model with Radial Basis Function(RBF) network based on genetic algorithm optimization. The results show that the model established by RBF network based on genetic algorithm optimization is more appropriate to achieve this transformation.
-
. 2012, 32(4): 106-110.Due to the availability of multisatellite altimetry and advances in numerical simulation methodologies in recent 20 years, recent global ocean tide models are well known to 2 cm RSS(root square of the sum of the squares of the 8 rms values) and with a spatial resolution of 50 km in deep ocean. The paper is aimed to validate the performance of five models by using tide gauge data. The results show that the performance of NAO99b is best in China sea areas, its RSS is 14.86 cm. Compared with other contemporary models, EOT10a fit the tide gauge data in global distribution better.
-
. 2012, 32(4): 111-115.On the basis of a regional CORS reference network, single differenced OMC between satellites were modeled with polynomial fitting model. Rover receiver within the network coverage can get OMCs by interpolation,
widelane phases. Widelane phase observation can be corrected with the OMCs.With the corrected widelane observations and ionospherefree code observations, widelane ambiguities can be fixed instantaneously. Once the widelane ambiguities were fixed, widelane phase observations become precise code observations, with ionospherefree phase, instantaneous PPP convergence can be achieved. The strategy is validated experimentally with Jiangsu CORS reference network,
whose baseline lenths are 49 km and 110 km respctively. The validation confirms that with regional enhancement, widelane can be fixed in two epochs, PPP convergence can be achieved simultaneously. -
. 2012, 32(4): 116-119.We introduce a quadratically linearized LAMBDA method considering the baseline length. The experimental simulation results are given and they show the effectiveness of the proposed method. Apart from its efficiency, under proper conditions the method is shown to have the same success rates of ambiguity resolution as the constrained LAMBDA method.
-
. 2012, 32(4): 120-124.To improve the GPS leveling fitting accuracy of complex terrain, the authors analyzed the accuracy and application state of EGM2008. Through taking two test areas in Northwest China as examples, the accuracies of height fitting were studied with the method of removingrestoring Earth gravity field combined with conventional GPS leveling fitting and comparison with the result only with conventional method. The results show that the removingrestoring method based on Earth gravity field can achieve better accuracy in complex terrain areas.
-
. 2012, 32(4): 125-128.Taking the analysis of the surface deformation monitoring of Beijing through 31 ENVISAT image from 2004-2010,as an example, the result of analysis show that the SBAS timeseries of the deformation of PS points is little more continuous in space than that of PS and the experimental results show that the result of SBAS and PS are in good agreement and close radically to the monitoring result of Beijing subsidence monitoring site warning forecast system so the result of PS and SBAS is reliable.
-
. 2012, 32(4): 129-134.A method of POSsupported indoor fixedorbit mobile photogrammetry based on RFID technology had been researched. RFID, relying on its noncontact identification function, can locate exposure position, and meanwhile, separate and identify electronic tags according to the unique code stored inside, so that it could determine, at the moment of exposure, the elements of exterior orientation obtained beforehand and which will be taken as weighted measurements to engage in bundle block adjustment, and the corresponding error equations can be given. The method can solve the problem of indoor fixedorbit mobile photogrammetry under certain circumstances in which only fewer control points can be placed.
-
. 2012, 32(4): 135-138.Ordinary digital camera is a kind of nonmetric camera, it has large image distortion but the method for photogrammetric measurement has a certain adaptive. The relative orientation is the key measurement of aerial photogrammetry, the method of successive iterative relative orientation and the direct relative orientation their quality have been studied and evaluated. Summing up the particularity of nonmetric camera’s relative orientation of closerange digital imagery in engineering application, we proposed two methods of joint calculation of the relative directional orientation elements.
-
. 2012, 32(4): 139-143.Satellite and receiver’s Initial Phase Biases (IPBs) have a significant influence on ambiguity resolution and convergence time of precise point positioning (PPP).The current receiver IPB is experimentally confirmed to be different when the receiver is turned off and back on. However, its underlying characteristics are seldom investigated in available literatures. On the basis of receiver design and carrier phase measurement mechanism, the article analyzed the impacts of frequency synthesizer, mixer, digital down converter and tracking loop on carrier phase measurement generation. Meanwhile, the mathematical models of carrier phase measurement and IPB are derived. Finally, the receiver IPB’s longterm stability and characteristics according to loss of lock, time adjust and poweron cycle are validated by experiment using navigation signal source and receiver platform.
-
. 2012, 32(4): 144-147.The tracking performances of three discriminator functions based on Delay Lock Loop (DLL) were studied: Early Minus Late Power (EML Power), Early Minus Late Envelope (EML Envelope) and Dot Power (DOT). A new mode that shifting discriminator function based on the tracking state is proposed to improve the performance of tracking loop. The experimental results tested by actual IF data show modified discriminator tracking signal effectively.
-
. 2012, 32(4): 148-151.Aimming at the ambiguity float solution of reducing the correlation and its variance arrary,
a new ambiguity search algorithm based on improved particle swarm optimization (IPSO) was proposed.
For the integer nature of double difference ambiguity,real code were modified to round in coding and made up of particle individual.Through
adaptive calculation of inertia weight and particle mutation,IPSO has improved the global convergence and robustness of standard particle swarm optimization to search carrier phase integer ambiguity.The testing example indicates that the new method not only increased the success rate of fixing ambiguity,but also improved the search efficiency,and it spent the same amount of time with LAMBDA,and less time than that genetic algorithm did.The new method is fast and reliable,and will make great application significance to ambiguity resolution of GPS shortbaseline. -
. 2012, 32(4): 152-155.VP Vertical Pendulum Tiltmeter is a new seismological observation instrument used in recording earth tides. A new calibration platform based on the PZT made in German is designed. The platform meets the design requirements that the accuracy is up to 10 nm.
-
. 2012, 32(4): 156-159.The main research focuses on the errors effect of vertical pendulum tiltmeter platform leveling in three aspects,and proposes the improved methods. On the basis of the existing platform leveling tiltmeter data, the structural and environmental factors in the systematic errors arising from tiltmeter are analyzed and calculated. By improving the mechanical structure and the platform components parameters to reduce errors,the technical requirements is achieved.
