大地测量与地球动力学
 
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2009 Vol.29 Issue.1
Published 2009-04-08
地壳形变与地震
1 OBSERVED STRAIN CHANGES FROM 4-COMPONENT BOREHOLESTRAINMETER NETWORK BEFORE 2008 WENCHUAN EARTHQUAKE
Qiu Zehua;Tang Lei;Zhou Longshou;and Kan Baoxiang
Following three criteria to testify the precursory anomaly before a great earthquake is adopted, 1) a normal background; 2) not interferences; 3) close correlation to the event. According to these criteria, no obvious abnormal changes related to the Wenchuan earthquake were found in preliminary investigation on the recordings of the 4component borehole strainmeters installed in the Tenth Five Year Project of CEA. A further study on the principal orientations of strain changes before the great shock shows that they did not all point to the epicenter.
2009 Vol. 29 (1): 1-5 [Abstract] ( 2224 ) PDF (2952 KB)   ( 2969 )
6 STUDY ON RELATION BETWEEN VARIATION OF LOCAL GEOIDAND EARTHQUAKE BY REPEATED GRAVITY SURVEY
Wang Shuangxu;Xue Fuping;Liu Liwei;Xu Yunma;and Zhang Xi
On the basis of the repeated observational data of seismic gravity network since 1990s in Qilianshan-Hexi area, the changes of local geoid in different time scale are calculated with Bruns formula and approximately solution of Stokes’ integral those are usually used for getting the difference of geoid from gravity field model. The variation of local geoid and the relation to geologic tectonic and seismicity are researched. The conclusions are that the general shape of local geoid variation in Qilianshan-Hexi area has divisional property, and the evolvement of local geoid for different periods is nonstationary. The detail variation of local geoid is related to the position of earthquakes from the data before several Ms6.0 earthquakes.
2009 Vol. 29 (1): 6-10 [Abstract] ( 2117 ) PDF (1237 KB)   ( 4089 )
11 STRESS TRANSFER BETWEEN 1997 MANYI Mw7.6 EARTHQUAKE AND 2001 KOKOXILI Mw7.8 EARTHQUAKE
Wang Jianjun;and Xu Caijun
The contribution of postseismic relaxation to the induced Coulomb stress and its comparison with that of static Coulomb stress changes imparted by 1997 Mw 7.6 Manyi earthquake were investigated. The results show that standard deviation of combined static and viscoelastic Coulomb stress changes and their means are not larger than 0.005 MPa,which is less than typical triggering value 0.01 MPa, indicating there was no obvious triggering effect on 2001 Kokoxili earthquake caused by static and viscoelastic Coulomb stress imparted by 1997 Manyi earthquake. Stress redistribution due to postseismic relaxation of lower crust or upper mantle didn’t dramatically affect stress environment around the hypocenter of 2001 Kokoxili earthquake. It might be that the dynamic Coulomb stress decaying more slowly than those other two which offered the contribution to triggering the 2001 Kokoxili earthquake.
2009 Vol. 29 (1): 11-14 [Abstract] ( 2222 ) PDF (728 KB)   ( 3594 )
15 ANALYSIS ON EXPLOSIVE SEISMIC WAVE WITH LARGE YIELD
Yang Jialiang;Hu Bin;Wang Xiaoshan; Peng Yuanqian;Ran Zhijie;Wen Chao;and Diao Guiling
Through the analysis on the records of digital seismic network in the Capital area and mobile network of the
Earthquake Administration of Hebei Province, it is found that explosive seismic wave is obviously different in its propagating feature from that of the natural seismic wave. The main characteristics of the explosion are as follows: 1) the explosive energy decayes quickly, wholly with
e -1.5; but the decaying rate is apparently different in near field(<20 km) and far field(>20 km);2) there are phenomenon of increasing energy at part of far field stations; the increase and decrease of the amplitude of explosion wave is not related to the station location of well or ground, but to the site effect, which reflects the overlapping effect of many kinds of waves;3) the S wave velocity of explosion is obvious lower than that of natural earthquake, while P wave velocity is similar, it may be related to the cause that explosion is not favorable to stimulate shear wave.
2009 Vol. 29 (1): 15-19 [Abstract] ( 1992 ) PDF (2826 KB)   ( 3367 )
21 STUDY ON COSEISMIC DEFORMATION OF WENCHUAN EARTHQUAKE BY USE OF L AND C WAVEBANDS OF SAR DATA
Jiang Mi ;Ding Xiaoli ;Li Zhiwei;Zhu Jianjun ;Yin Hongjie ;and Wang Yongzhe
It describes the results of the ground motion monitoring over Wenchuan earthquake sites in the southwest of China
with the ALOS PALSAR and ENVISAT ASAR sensors based on the differential interferometric synthetic aperture radar (DInSAR) technique. In recent the Cband data were mainly used to detect the ground deformation, but the results of interferometry are limited by high vegetated areas and rugged terrains. The study purpose is to demonstrate that these constraints decrease significantly at Lband data due to its spatial resolution and the longer wavelength. The real and simulated data also show Lband data sets are more appropriate for detecting the deformation over the rugged terrain and high vegetation area. Especially, for the large deformation gradient area, PALSAR images are not likely to generate interferometric phase aliasing which goes against the phase unwrap.
2009 Vol. 29 (1): 21-26 [Abstract] ( 2299 ) PDF (4258 KB)   ( 3702 )
27 STUDY ON GRAVITY CHANGE AROUND WENCHUAN Ms8.0 EARTHQUAKE RECORDED IN JI-LU-YU JUNCTION AREA
Xie Ruyi;Li Qinglin;Qin jianzeng;Zhang Ruiming;Xu Shunqiang;and Feng Jianlin
Gravity changes around the Wenchuan Ms8.0 strong earthquake are probed using the gravity data in many period of time from mobile gravimetric observation network which is located at junction area of Hebei, Shangdong and Henan province(Ji-Lu-Yu). The results revealed that in the period of earthquke preparation in a definited area there was a negative gravity
anomaly whose maximum value was 43×10 -8 ms -2, nearly before the earthquake occuring and then gravity should be restored up after the earthquke.
2009 Vol. 29 (1): 27-30 [Abstract] ( 2073 ) PDF (3164 KB)   ( 3126 )
31 STUDY ON MAPPING SEISMIC INTENSITY DISTRIBUTION FROM RS DATA
Cai Shan ;Zhang Jingfa ;Chen Wenkai ;Zhang Lei ;and Dai Yaqiong
Through remote sensing(RS) the damage information of a large area can be obtained in spite of traffic condition, so using remote sensing data to map seismic intensity distribution is of great advantage. Seismic intensity distribution is mapped on the basis of the Chinese Seismic Intensity Scale by analyzing the damage of constructions, roads and bridges, and earthquakeinduced geological disasters.Finally, experiences and problems of mapping seismic intensity distribution by RS data are summarized.
2009 Vol. 29 (1): 31-35 [Abstract] ( 2146 ) PDF (5113 KB)   ( 3572 )
36 IN-SITU CALIBRATION OF GUZA STATION’S 4-COMPONENT BOREHOLE STRAINMETER
Kan Baoxiang ;Qiu Zehua ;and Chi Shunliang
In order to improve the accuracy of observations and make further research, the insitu relative calibration and absolute calibration of the 4component borehole strainmeter at Guza station were made. In these calibrations, the influence of phase lag on the coupling coefficients sufficiently was considered and eliminated, thus the accuracy of the coupling coefficients has been obviously improved after insitu calibration.
2009 Vol. 29 (1): 36-40 [Abstract] ( 2188 ) PDF (1557 KB)   ( 3320 )
41 3D DENSITY INVERSION WITH GENETIC ALGORITHM
Ke Xiaoping;Wang Yong;and Xu Houze
A new inversion method for 3D density structure is proposed, which combines the method of gravity forward of 3D rectangular prism with genetic algorithm, the approach of constructing the objective function and the procedure of genetic algorithm are introduced. The validity and stability of this method are proved by synthetic data. With this method the threedimensional distribution of density in eastern QinghaiTibet plateau is inverted from Bouguer gravity anomaly.
2009 Vol. 29 (1): 41-45 [Abstract] ( 2059 ) PDF (3285 KB)   ( 3471 )
46 ON SPHERICAL MANTLE MIXTURE DRIVEN BY MODERN PLATE TECTONIC MOTION
Shan Bin;Fu Rongshan ;and Zheng Yong
This paper simulated the pattern of mantle convection and its evolution process under the driven force from modern plate tectonic motion based on a 3D mantle convection model and then analyzed the mantle mixture effect further.The results show four main characteritics of mantle mixture: 1) Degree of mantle mixture is mainly controlled by tectonic driven forces. 2) The degree of material mixture in the upper mantle is higher than that in the lower mantle. About 80% elements in the upper mantle and 60% in the lower mantle have been past through by at least two curves. 3) The degree of mantle mixture also depends on the convection time. The longer the time, the higher the degree of mixture, but the trend of mixture increase is getting downward, that makes the existence of mantle heterogeneities under the full mantle convection environment possible. 4) Mantle convection type can affect the mantle mixture in quite a deal. The existence of toroidal convections can make the material travel much longer distance than spheroidal convections, thus increase the mixture effect efficaciously.
2009 Vol. 29 (1): 46-51 [Abstract] ( 1932 ) PDF (2845 KB)   ( 3699 )
52 FAULT PARAMETER INVERSION WITH ANT COLONY ALGORITHM BY DISLOCATION MODEL
Liu Ning;and Zhang Yongzhi
The ant colony algorithm is modified by replacing tour length and visibility based on the characteristics of fault parameters, and combined with the theoretical dislocation model, using the GPS observations in the northeast edge of the QinghaiTibet plateau during 1999—2001, the Qilian fault 3D slip rates are inversed.The results show that the ant colony algorithm is effective for solving the problem of inversion of 3D fault slip rate parameters, the results of the numerical inversion has the good consistency with those of geological methods.
2009 Vol. 29 (1): 52-56 [Abstract] ( 1889 ) PDF (1194 KB)   ( 3372 )
理论方法研究
57 RESEARCH ON FITTING LINE AUTOMATIC EXTRACTION ALGORITHM OF 3D LASER SCANNING
Pan Guorong;Gu Chuan;Wang Suihui;and Cai Runbin
Because of the existence of a large amount of points with gross error in scanned point cloud, many robust algorithms have been adopted to processing range images data. These algorithms often randomly establish a large amount of modules firstly, and then identify them individually,so this course is very inefficient. This paper presents an improved RANCAC algorithm which fully utilizes the intrinsic attributions of scanned line data. The algorithm is both efficient and robust. More rational segmentation results can be obtained using the proposed algorithm.
2009 Vol. 29 (1): 57-63 [Abstract] ( 2115 ) PDF (2386 KB)   ( 3809 )
64 GEOMETRY ORBIT DETERMINATION OF GEO SATELLITE ATTENDING TO SYSTEMATIC ERRORS
Xu Tianhe;and He Kaifei

The basic principle of geometry orbit determination for Geosatinoary Earth Orbit (GEO) satellite is introduced. The mathematical model, parameter estimators and the formula of correlative coefficients between the estimated parameters are derived for geometry orbit determination of GEO satellite with systematic errors. A simulated numerical example is conduced for three types of systematic error, the constant, the linear polynomial, and the quadratic polynomial by using the proposed method. The results show that the influence of systematic errors on the geometry orbit can be efficiently controlled with the new method. There is strong correlativity between the systematic error parameters and X, Y components, and the correlative coefficients change with the variation of PDOP. The correlativity between them and Z component is low. All these result in the precision decrease of X and Y components, and the precision is almost of Z component uninfluenced.
2009 Vol. 29 (1): 64-69 [Abstract] ( 2271 ) PDF (2751 KB)   ( 3324 )
70 MORE STUDY ON PRECISION OF HOMOLOGOUS CENTER PED TO ARBITRARY PEG IN TRAFFIC LINE
Deng Yonghe
On the basis of the error spread law and the theory of position error in arbitrary direction of point，it is put forward and demonstrated that transverse position error equals to zero and longitudinal position error equals to the error of point position.Besides,error curve and error ellipse are analyzed.So, it is shown that error ellipse is inutility, and error curve is useful and effective.
2009 Vol. 29 (1): 70-73 [Abstract] ( 2096 ) PDF (429 KB)   ( 3073 )
74 COMPARATIVE RESEARCH ON EQUALITY CONSTRAINT INVERSION AND JOINT INVERSION
Wang Leyang;and Xu Caijun
Prior information and many kinds of observations are fully used in equality constraint inversion and joint inversion. Definitions, inversion models and objective functions’ formation methods of equality constraint inversion and joint inversion are discussed. The definitions of constraint inversion, equality constraint inversion and inequality constraint inversion are given. At last, some important conclusions are drawn through the calculation and analysis of an example.
2009 Vol. 29 (1): 74-78 [Abstract] ( 2081 ) PDF (497 KB)   ( 3044 )
79 EFFECT OF OBSERVATION NOISE ON DATA FUSION BY FREQUENCY DOMAIN INPUT-OUTPUT METHOD
Cui Lilu ;Luo Zhicai ;Zhong Bo ;and Wang Haihong;
The local geoid or gravity anomaly as an example is refined by the fusion of the simulated geoid height and gravity anomaly data,and the effects of observation noise level and nonstationary noise to the data fusion results are analyzed. Simulation tests show that the satisfactory results can be obtained by the fusion of different observation noise level data or nonstationary noise data with doubleinput singleoutput method.
2009 Vol. 29 (1): 79-82 [Abstract] ( 2176 ) PDF (461 KB)   ( 4039 )
83 REFINEMENT AND APPLICATION OF CHENGDU QUASI-GEOID
Li Chunhua;Huang Dingfa ;Luo Zhicai ;and Deng Fang
By use of 10 314 discrete gravity data, 211 GPS/ leveling data, digital terrain model with 30″×30″ resolution and global earth’s gravity field model WDM94,the quasigeoid of Chengdu with 1′×1′ resolution, is constructed with removerestore technique. The modeled geoid heights are tested with observed 20 GPS/ leveling data that were not applied to the construction of Chengdu quasigeoid. The test results show that the standard deviation of the differences is ±0.009 m. The systematic bias of the two traditional vertical network was detected and analyzed by use of Chengdu quasigeoid.
2009 Vol. 29 (1): 83-87 [Abstract] ( 2101 ) PDF (3111 KB)   ( 3214 )
88 RESEARCH OF IMPROVED FICTIOUS COMPRESS RECOVERY APPROACH FOR APPROXIMATING LOCALLY DISTURBING GRAVITY
Zhou Shichang;Wang Qingbin;and Zhu Leiming
To approximate the disturbing gravity, the fictitious compress recovery approach is used and compared with the approach of point mass.The results show that the accuracies and the computation speed of these two approaches are equivalent to each other.
2009 Vol. 29 (1): 88-90 [Abstract] ( 1935 ) PDF (758 KB)   ( 3008 )
91 LIMITATIONS OF SATELLITE ALTIMETRY AND FUTURE TECHNOLOGY IMPROVEMENTS
Wang Haihong;Zhong Bo ;Wang Wei ;and Yu Dan
Limitations of conventional satellite altimetry are summarized. The principles of four new altimetry techniques including Kaband altimetry, constellation technology, GNSS altimetry and wideswath altimetry are introduced.The advantages and disadvantages of these new techniques are analyzed. The implementation of these techniques will complement the conventional altimetry, and greatly extend the applications of satellite altimetry.
2009 Vol. 29 (1): 91-95 [Abstract] ( 2234 ) PDF (977 KB)   ( 5124 )
96 RESEARCH ON A NOVEL INDEX FOR ASSESSMENT OF INTERFEROGRAM QUALITY
Zhao Chaoying;and Zhang Qin
Interferogram of two coregistrated master and slave images is one of the main products in the SAR interferometric processing, and the filtering of interferogram is a key step for rational unwrapping. So the quality of interferogram can not only be applied to assess the coregistration precision, but also be used to determine the filtering factor and assess the filtering effect. According to the basic principle of the method of sum of phase difference (SPD), this paper puts forward the
phase difference and index with considering the 2π discontinuity and weighted phase difference and index,where the weight is determined by coherence value. This quality map can assess the interferogram with 2π discontinuity and highlight the low coherence area. Finally,the advantage of this quality index is proved by the DEM interferogram of the Xi’an area taken as an example.
2009 Vol. 29 (1): 96-100 [Abstract] ( 2145 ) PDF (6255 KB)   ( 3291 )
101 RESEARCH ON GNSS DATA PRE-PROCESSING METHODS
Yang Xia;Dang Yamin;Cheng Yingyan ; and Yang Zheng
The integration of multiple systems will be the new technical direction of GNSS as the development of GPS, GLONASS, GALILEO. On the basis of the analysis of the timespace reference, orbit standardization, data choice, cycle slips detection, etc. the multisatellite system data preprocessing methods and their program realizations were researched.
This study shows we make if the methods used in single systems extend appropriately then it can be used in integration systems and the preprocessing results will be fine.
2009 Vol. 29 (1): 101-105 [Abstract] ( 2109 ) PDF (1039 KB)   ( 3463 )
106 OPTIMAL SEGMENTATION SCALE MODEL BASED ON OBJECT-ORIENTED ANALYSIS METHOD
He Min;Zhang Wenjun;and Wang Weihong
Objectoriented image analysis method is suitable for information extraction from highresolution remote sensing image, the core issue is to achieve the multiscale segmentation for highresolution remote sensing image. It is proposed an optimal splitscale model of multiscale segmentation based on objectoriented analysis methods, and made the experiment of image segmentation and the evaluation of segmentation quality. The results show that after this model the reliable optimal split scale can be obtained conveniently.
2009 Vol. 29 (1): 106-109 [Abstract] ( 1935 ) PDF (1204 KB)   ( 3980 )
110 STANDARDIZATION OF GPS SATELLITE ORBITS BASED ON MOVING INTERVALS
Chang Liang;and He Xiufeng
It is found that when conventional methods,such as Trigonometric Interpolation,are used for standardization of GPS satellite orbits,
and the order of interpolation or fitting increases, the accuracy will decrease. Thus, a conception of moving intervals is proposed
solving this problem. The results from computing and analyzing the precise ephemeris supplied by National Geodetic Survey of U.S. as an example show that this standardization method based on the moving intervals can solve the problem on accuracy decreasing i.e.,as the order increases, in the same time, the accuracy of standardizing GPS satellite orbits is improved to the level of subcentimeter.
2009 Vol. 29 (1): 110-113 [Abstract] ( 1859 ) PDF (1664 KB)   ( 3087 )
114 ANALYSIS OF RELIABILITY OF DATA PROCESSING OF GNSS NAVIGATION PLATFORM
Xu Changhui;Wang Jian;Gao Jingxiang ;and An Wei
To evaluate the reliability of GNSS navigation platform data processing, their internal and external reliability indices are discussed, and the simulation with Monte Carlo method is used to assess the reliability of dilution of precision. The results show that the dilution of precision, internalreliability and externalreliability are not high in the individual GPS and GLONASS, but they are obviously improved in the combination of the two systems, even the reliability of elevation is not good enough yet. When Galileo’s is introduced, the geometry, the horizontal dilution of precision(HDOP) and its reliability are improved, as well as, the vertical dilution of precision(VDOP) and its reliability are greatly improved.
2009 Vol. 29 (1): 114-118 [Abstract] ( 2264 ) PDF (1746 KB)   ( 3194 )
119 TIME SERIES FORCASTING MODEL OF GROUND SURFACE DEFORMATION CAUSED BY CURTAIN GROUTING FOR COAL MINE SHAFT
Sun Jialong;Guo Shuyan ;and Guo Jinyun;
Some displacements and deformations for the mine shaft working over past many years’ may occur.Curtain grouting is one of efficient methods for protecting the shaft and the surface around the shaft from the harm. The deformation caused by grouting around mine shaft is monitored with a reasonable scheme and the measured data are processed with the timeseries theory to analyze and forecast the dangerous deformation. Through analyzing different time series at different monitoring points, it is found out that the degree of forecasting precision and the accuracy ratio of forecasting model established with meaninterval timeseries are best.
2009 Vol. 29 (1): 119-122 [Abstract] ( 2071 ) PDF (720 KB)   ( 2481 )
123 ALGORITHM FOR GENERATION OF GPS VIRTUAL PHASE OBSERVATION BASED ON VRS
Zhu Chao;Gao Chengfa ;Zhao Yi;and Peng Hui
The key technique of network differential positioning based on virtual reference station，the algorithm the generation
of virtual phase observation and differential corrections was proposed. At the same time，in order to evaluate the feasibility and location precision of the proposed technique，field tests were caried out based on the measured data of a continuous operating reference
station network and by use of selfdeveloped positioning software SeuVRS1.0. The results of test which conducted using regional networks demonstrate that distancedependent errors can be effectively modeled between reference stations.Within the network，real time kinematic positioning based on virtual reference station can be achieved,with better than 4 cm accuracy in horizontal position.
2009 Vol. 29 (1): 123-126 [Abstract] ( 2067 ) PDF (918 KB)   ( 3716 )
127 DETERMINATION OF GPS RECEIVER’S DCB
Song Xiaoyong;Yang Zhiqiang ;Jiao Wenhai ;Mao Yue ; and Feng Laiping
The determination of differential code biases (DCB) plays an important role in many GPS applications supported by code observations which include precise point positioning, ionosphere monitoring and the time transfer among GPS observation stations. The mathematical model for estimating the DCB is presented, which is based on the phase-smoothed code. The DCB for receivers of the reference station in CMONOC were determined with GPS observations of these stations in 2003, and daily and monthly variations of DCB were analyzed. It’s showed that the accuracy of DCB can be better than 1 nanosecond and the DCB of the reference station in the CMONOC have no remarkable variation during the time period considered.
2009 Vol. 29 (1): 127-131 [Abstract] ( 2084 ) PDF (2242 KB)   ( 4839 )
132 APPLICATION OF ADAPTIVE COLLOCATION METHOD TO CRUSTAL DEFORMATION ANALYSIS
Zhao Lihua ;and Zeng Anmin;
As there are relatively few observed points in crustal deformation monitoring, it is hard to deduct the deformation of the unobserved points correctly with conventional methods. On the basis of the characteristics of the crustal deformation, the collocation method is proposed to be used, with which not only the influence of present random variation of observation points can be taken into account and the variation of the observed points can be found properly but also the deformation information of the unobserved point can be obtained.Futhermore,since the common collocation method is difficult to determine properly the weight proportion between the observation noise and stochastic signal, this paper adopts the adaptive collocation method, that is, modulating the proportion of the stochastic signal and observation noise with an adaptive factor to improve the accuracy of the deduction of the variation of the unobserved points. Finally, a measured crustal deformation monitoring network is calculated and analyzed, and the results prove the effectivity of the proposed method.
2009 Vol. 29 (1): 132-134 [Abstract] ( 2163 ) PDF (544 KB)   ( 3008 )
135 APPLICATION OF MOHR-COULOMB EQUIVALENT AREA YIELD CRITERION TO SLOPE STABILITY ANALYSIS
Li Yin ;Su Kai ;and Li Jie;
On the basis of the extended Drucker-Prager yield criterion in ABAQUS program, Mohr-Coulomb equivalent area circle yield criterion is adopted and how the equivalent material parameters are calculated is described. The divergence is assumed as the flag to tell the slope sliding. And the stability of a certain typical soil slope is analyzed by use of MohrCoulomb yield criterion with different circle, such as circumscribed circle, inscribed circle, internal tangential circle and equivalent area circle. When the material parameter k is 0.8, compared by the limit equilibrium methods, the safety factors of slope under MohrCoulomb yield criterion with circumscribed circle and inscribed circle are bigger but that with internal tangential circle less,and that with equivalent area circle closest. Furthemore, with the increasing of k, the iterative computation converges more easily and the safety factor of slope becomes too big, so the value of k is suggested to take from 0.8 to 0.9.
2009 Vol. 29 (1): 135-139 [Abstract] ( 1999 ) PDF (1535 KB)   ( 3302 )
140 GIS ACQUISITION SYSYEM BASED ON PDA FOR REALIZATION OF GPS PRECISE POINT POSITIONING
Li Xingxing ; Luo Tao ;Zhang Xiaohong ;and Liu Wanke
At present, the users need a flexible syetem (without basestation) to provide realtime positioning service of meter level precision in many application fields. The advantages and significance of integration of the mobile technology, GPS precise point positioning and GIS are analyzed and the GIS data acquisition system based on PDA and GPS precise point positioning are realized. The process of realizing the whole system as well as the key technologies is presented. Finally,the experimental results demonstrate that the system is feasible and able to meet the practical needs of GIS data acquisition with meter level precision in horizontal direction.
2009 Vol. 29 (1): 140-143 [Abstract] ( 2148 ) PDF (1195 KB)   ( 3223 )
观测技术
144 A FIBER BRAGG GRATING TEMPERATURE SENSOR WITH ADJUSTABLE SENSITIVITY
Li Kuo;and Zhou Zhenan
As a novel sensing element, Fiber Bragg Grating (FBG) is sensitive to both temperature and strain. On the basis of this character, we designed and manufactured a FBG temperature sensor with adjustable and high sensitivity. By adjuseing its sensitivity, its temperature range can be changed, which enlarges the application field, so the problems of storage and transport is solved.
2009 Vol. 29 (1): 144-147 [Abstract] ( 1997 ) PDF (2301 KB)   ( 3120 )
148 RESEARCH ON METHODS FOR PREDICTING CLOCK ERROR BASED ON DOMECTIC HYDROGEN ATOMIC CLOCK
Zhu Lingfeng;Li Chao;Liu Li;Chen Liucheng;and Dong Enqiang
Grey system model, quadratic polynomial model and simple polynomial model are used for predicting hydrogen atomic clock error made in Shanghai observatory. The calculating results show that the accuracy of predicting clock error of grey system model and simple polynomial model is equal, which exceeds that by quadratic polynomial model.When the time for data sampling is short, the accuracies of predicting clock error by use of grey system model and simple polynomial model exceed quadratic polynomial model obviously.
2009 Vol. 29 (1): 148-151 [Abstract] ( 1911 ) PDF (1317 KB)   ( 3118 )
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