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Table of Content

    24 April 2000, Volume 20 Issue 2 Previous Issue    Next Issue
    论文
    AN APPROACH TO STUDY THE DAY-TO-DAY VARIATIONS OF IONOSPHERIC TEC DIRECTLY BY GPS TIME-DELAY SIGNALS
    XIAO Zuo;ZHANG Donghe
    2000, 20 (2):  97-102.  doi: 10.11728/cjss2000.02.097
    Abstract ( 1664 )   PDF (560KB) ( 1833 )   Save
    In this paper, an approach was presented to deduce the diurnal variation ofionospheric TEC through only the measured data of time-delay (pseudo-range) ofGPS signals without using any phase information. Thus the procedure to studyTEC day-tcaday vaxiations is greatly simpllfied. In this method, satellite clock biascan be removed self consistently in the calculations while the receiver clock erroris corrected by using the average night values from IRI model- In this way someabsolute error due to receiver clock may still exist, but this does not infiuence thestudy of day-to-day vaxiations. The calculated vertical TEC is the average of verticalprojections of all the line-of sight TEC from differellt satellites in a conical angleof 60 degrees around the local vertical direction. An example of three consecutivedays' TEC variation was given, which shows the validity of the method suggestedin this paper. Finally it is pointed out that in the case of large zenith angle ofsatellite, ionospheric irregularities may contribute certain amoullt to the multi-patheffect.
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    A PHYSICAL MODEL FOR IONOSPHERIC VERTICAL PROFILE AND COMPARISON BETWEEN IT AND IRI-90
    DENG Yue;WANG Jingsong;XIAO Zuo
    2000, 20 (2):  103-112.  doi: 10.11728/cjss2000.02.103
    Abstract ( 1486 )   PDF (579KB) ( 1246 )   Save
    A physical model for ionospheric vertical profile is established, taking into ac-count four species of ions and electrons in the region of 80-500 km. Neutral windand ions' motion are both involved in the continuity equations for those five species.Ionospheric proflles in different seasons at low and high solar activities are calcu-lated and compared with the results from IRI-90. Results show that E region is atypical Chapman layer and the depth of E-F valley is generally 0.2-0.5 which isdeeper than that given by IRI-90. That the F1 ledge is most obvious in summerat low solar activity is consistent with widely accepted theories, but the F1 ledgeseldom appear in IRI-90. In F2 region, the electron number density at high solaractivity is greater than that at low solar activity, and in winter is greater than thatin summer. rhese all agree with observations rather well.
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    DETECTION OF SCHUMANN RESONANCE IN THE IONOSPHERE F REGION
    ZHAO Zhengyu;XIE Shuguo;A. Masson;F. Lefeuvre
    2000, 20 (2):  113-120.  doi: 10.11728/cjss2000.02.113
    Abstract ( 1555 )   PDF (500KB) ( 621 )   Save
    In this paper, simultaneous measurements of electron density and ELF elec-tric field by Aureol-3 satellite have been analyzed using high frequency resolutionspectral and cross-bispectral techniques. The detailed analyses of the data shows: first, the peaks in the power spectra of the electric field components are seen at theSchumann resonance frequencies in the high latitude ionospheric topside F regionand second, the harmonics are associated with positive density gradients.
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    NONLINEAR INTERACTION AMONG PLANETARY WAVE AND INERTIALGRAVITY WAVES IN THE MIDDLE AND UPPER ATMOSPHERE
    XIONG Jiangang;YI Fan;
    2000, 20 (2):  121-128.  doi: 10.11728/cjss2000.02.121
    Abstract ( 1839 )   PDF (504KB) ( 1420 )   Save
    The evolution equation of planetary wave and inertial-gravity waves are ob-tained from the anelastic equations based on a weakly nonlinear assumption. nomthe resonance surface and increase rate curve, it is found that the planetary waveprefers to interact with large scale inertial-gravity waves. By using the equivalentgravity wave assumption of tidal wavest the interaction among the typical 2 daysplanetary wave, semidiurnal tide and 9.6 hours inertial-gravity waves are investi-gated in detail. The exchange of energy between planetary wave and semidiurnaltide is found to proceed more strongly than the exchange between them and the9.6 hours inertial-gravity gravity. The variability of tidal and planetary wave am-plitudes may be caused by nonlinear interaction between them.
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    THE INFLUENCE OF BACKGROUND WINDS ON INTERNAL GRAVITY WAVES IN DISSIPATIVE ATMOSPHERE
    DING Feng;WAN Weixing;YUAN Hong
    2000, 20 (2):  129-135.  doi: 10.11728/cjss2000.02.129
    Abstract ( 1737 )   PDF (459KB) ( 1280 )   Save
    By using ray-tracing method, features of propagation of internal gravity wavesunder the influence of winds are calculated- The results indicate that the cut-offregion of gravity waves seems not affected by winds, while reflecting and propagat-ing regions are significantly innuenced. The reflecting region reduces when gravitywaves propagate downwind and expands when against wind. In propagating region,propitions winds shorten the attenuation distance of slow gravity waves and reducetheir propagating height, while converse winds lengthen the attenuation distance ofslow gravity waves and rise the attenuation height. Further analysis shows that thediversity of gravity wave propagation features is caused by the effect of winds onthe processes of gravity wave attenuation and reflection.
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    RELATIONS BETWEEN IMF Bs EVENTS AND INTENSE MAGNETIC STORMS
    GAO Yufen;ZHANG Xiuling
    2000, 20 (2):  136-143.  doi: 10.11728/cjss2000.02.136
    Abstract ( 1639 )   PDF (517KB) ( 820 )   Save
    The relationship between IMF Bs. events (Bs > 10nT, VBs > 5mV/m andboth last more than 3h) and intense magnetic storms (Dst≤ -100 nT) is analyzedusing the solar wind and geomagnetic data from 1978-1988. The results showthat one hundred percent of Bs events can cause magnetic storms, but only 84% areintense storms. Although all the intense magnetic storms correlate to larger IMF Bsclosely only 68% of intense magnetic storms are actually caused by Bs events. Therelationship between Bs events and intense magnetic storms is not in correspondenceof one to one. The effects of magnetospheric background and fluctuations of Bs onthe cause of magnetic storms must be taken into account. Also the attention shouldbe paid to the fact that Dst indices are affected by many electric current systemsafter than ring current.
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    DEPENDENCE OF FIELD-ALIGNED CURRENTS ON THE ORIENTATION OF THE INTERPLANETARY MAGNETIC FIELD
    JIAO Weixin;PU Zuyin
    2000, 20 (2):  144-149.  doi: 10.11728/cjss2000.02.144
    Abstract ( 1612 )   PDF (380KB) ( 1201 )   Save
    Field-aligned currents (FACs) measured in the inner magnetosphere by theISEE-1 and -2 spacecraft are investigated as a function of the Interplanetary Mag-netic Field (IMF) orientation and the level of geomagnetic activity, as indicatedby the AL index. It is found that~75% of the FACs observed are associated withsouthward IMF. The remaining 25% occur during the period of IMF turning fromsouthward to northward- Very few are associated with sustained intervals of north-ward IMF. Approximately 75% of the FACs occur when the AL index is < -150 nT.The current intensity and density are higher for both southward IMF and high gecrmagnetic activity. These results show that the occurrence of FACs within the innermagnetosphere is controlled mainly by the IMF, with the actual occurrence being aconsequence of enhanced electrodynamic coupling between. the solar wind and themagnetosphere- ionosphere system.
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    DRIFT SHELL TRACING METHOD AND THE SECULAR VARIATION OF INNER RADIATION FLUXES
    FANG Xiaohua;PU Zuyin
    2000, 20 (2):  150-158.  doi: 10.11728/cjss2000.02.150
    Abstract ( 1459 )   PDF (496KB) ( 1375 )   Save
    The AE-8/AP-8 models, which were constructed by NASA with satellite obser-vation data in the 1960s and 1970s, have long been considered to be the standardtrapped radiation models. It seems that they will continuously be used for a certainperiod of time in the future. The weakening of the geomagnetic field causes the driftshell of a charged particle to descend and the structure of the Trapped RadiationBelt to deform. Thus it is of importance to correctly use the AE-8/AP-8 models inthe contemporary era. However, up to now there seems to be no consensus on thisissue- On the basis of physical analysis, we propose the Drift Shell Tracing Method(DSTM) in this paper to solve the problem. The DSTM provides a reasonable wayto apply the standard trapped radiation models within the adiabatic approximation. The calculation results indicate that the change of the geomagnetic field playsa significant role in the particle redistribution in the inner zone. It is found that inthe past three decades,the central location of the particle South Atlantic Anomaly(SAA) has drifted westward almost 20° in longitude and northward almost 1Oo inlatitude. In the altitudes of 300-400 kilometers, the intensity of proton flaxes hasvaried dramatically and the flux difference at the same location can even be up to3-4 orders of magnit1lde.
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    CIRCULAR HOLLOW PLASMA WAVEGUIDE IN AN EXTERNAL MAGNETIC FIELD
    HU Binjie;ZHANG Guoji;LAI Shengli
    2000, 20 (2):  159-164.  doi: 10.11728/cjss2000.02.159
    Abstract ( 1591 )   PDF (419KB) ( 1235 )   Save
    The electromagnetic wave propagating along a circular hollow plasma wave-guide immersed in an external magnetic field is presented. Because of the boundaryconditions at all interfaces can be represented by the matrix equations, the char-acteristic equation can be obtained by using the matrix manipulation- The effectsof the plasma thickness of cladding, electron cyclotron frequency, and collision fre-quency on attenuation of the waveguide are investigated.
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    SOME FURTHER DISCUSSIONS FOR A METHOD OF TIME SERVICE WITH SYNCHRONOUS SATELLITE
    XU Jin
    2000, 20 (2):  165-171.  doi: 10.11728/cjss2000.02.165
    Abstract ( 1404 )   PDF (664KB) ( 1126 )   Save
    The time comparison with by means of synchronous satellite is a commonmethod, which has the advalltages of low cost, simple operation and wide scopeof service. The key technique for raising the precision of time comparison withthe method is to determine and predict the orbit of synchronous satellite moreaccurately Based on the improvement of the previous program for orbit determination and prediction, further in vestigations concerning time comparison using thismethod is conducted in this paPer. The experimental results show that the post-processing precision of time comparison obtained with the new program is aboutthe same as that obtained with the previous program, which is better than 1 ps,but the pre-processing precision has been raised greatly as compared to that olytained previously With the new program of orbit determination and prediction, thepre-processing precision of time comparison can keep better than 1 ps in one week.
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    THE SUCCESSFUL APPLICATION BASED ON A NEW AUTOMATIC TRACKING SYSTEM FOR BALLOON-BORNE ASTRONOMICAL OBSERVATION OBJECTS
    LI Xiaoqing;LIU Shanzhao;HANG Hengrong;WANG Nansen;GONG Yizhong;ZHANG Renjian
    2000, 20 (2):  172-176.  doi: 10.11728/cjss2000.02.172
    Abstract ( 1554 )   PDF (311KB) ( 656 )   Save
    This paper introduces the flight experiment based on a new automatic trackingsystem for balloon-borne astronomical observation objects. The tracking resultsof three objects are analyzed and their tracking charts are provided as well. Theworking principle and construction of the system are also described.
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    A STUDY ON LAUNCHING GEOSTATIONARY SATELLITE AT HIGH LATITUDE BY TAKEN ADVANTAGE OF THE MOON'S GRAVITATION
    ZENG Guoqiang;XI Xiaoning;REN Xuan
    2000, 20 (2):  177-184.  doi: 10.11728/cjss2000.02.177
    Abstract ( 1512 )   PDF (505KB) ( 1227 )   Save
    A method of make use of Lunar Gravitation (LG) to launch GeostationarySatellite (GS) at high latitude is preselited- At first, preliminary anaJysis of theproblem of launching GS is given using patchedconic technique. Then, preciseanalysis is given in a mathematical model. It is indicated that less energy is neededto launch GS from launch site with latitude higher than 28° using LG method thanthe traditional. The higher the launching site is, the more energy is saved.
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    AN OPTIMIZED METHOD TO CONTROL THE MOTION PLANNING OF SPACE MANIPULATORS BASE GENETIC ALGORITHM
    GE Xinsheng;ZHANG Qizhi;LIU Yanzhu
    2000, 20 (2):  185-191.  doi: 10.11728/cjss2000.02.185
    Abstract ( 1988 )   PDF (383KB) ( 3632 )   Save
    The problem of nonholonomic motion planning of space manipulator system isdiscussed in this paper. The problem of nonholonomic motion planulng of spacemanipulator is transformed into the optimized colltrol of nonlinear system by usingthe nonholonomic characters of the system. The genetic algorithm is introducedto solve the optimized control problem. Based on genetic algorithm for optimizedcontrol of nonholonomic motion planning of space manipulator is proposed. Theeffectiveness of the method is proved by the numerical simulation examples.
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