空间科学学报

1997 Vol. 17, No. 4

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INTERACTION BETWEEN INTERPLANETARY STRUCTURE AND QUASI-PARALLEL COLLISIONLESS SHOCK

LU Quanming, LI Yi, WANG Shui

1997, 17(4): 289-293. doi: 10.11728/cjss1997.04.289

Abstract(2249) PDF 328KB(644)

Abstract:
Using an onerdimension hybrid code, we numerically studied the interachorbetween tWo kinds of interplanetary structures (the plasmoid with high density andinterpanetary shock) and the quasi-parallel collisionless shock. The results show thatdue to the scarering of large-amplitude ultralow-frequency upstream waves, theplasmoid with high density begins to diffuse in the upstream, and it diffusesconhnuously in the downstream besides a little compression when it passes through theshock ramp. When the interpanetary shock close to the quasiparallel collisionlessshock,large-amplitude ultralow-frequency waves are formed in the upstream of theinterplanetary shock, and the sbength of the interplanetary shock are enhanced. Finallythe two shocks merge as a new shock which excites large-amplitude ultralow-frequencywaves in the upstream.

NUMERICAL SIMULATION FOR MAGNETIC SPONTANEOUS RECONNECTION IN SOLAR ATMOSPHERE(Ⅰ)

ZOU Limin, TANG Yuhua, DI Xiaohua, FANG Cheng, HU Youqiu

1997, 17(4): 294-302. doi: 10.11728/cjss1997.04.294

Abstract(1790) PDF 537KB(1009)

Abstract:
Under the considerahon of heat conduhvity, Joule's dissipation and abnormalresistance, thes paper studies numerically the spontanous reconnction can heat theatmosphere by Joule's dissipation of abnormal resisthee, and thes effect is dependentclosely on the value of β When β is 0.05, 0.1 and 0. 5, the heated atmospheretemperature can rise to 2.0×10⁶K, 1.0×10⁶Kand 4.0×10⁵K respectively, this mayaccount for the achve regions stahc heating and the preheating process of flares.Whn the bottom border is fixed, it will form naatly the helmetJike structure dueto the line-tied effect and the matter will fill down along two "legs" with thevelocity of more than 40km/s. this will lead to redshift of the spectrum.

INFLUENCE OF CHARGE FLUCTUATION ON DUST MAGNETOACOUSTIC WAVE IN SPACE DUST PLASMA

SHI Zhidong, LI Zhongyuan

1997, 17(4): 303-308. doi: 10.11728/cjss1997.04.303

Abstract(2424) PDF 359KB(1173)

Abstract:
Charging processes of dust gndns in plasma are analyzed. Aset of self-consistenttaewflulds equahons are given for dust Plasma. From these equaons, fluctuation ofcharge on dust grain is stUdied and dispersion relations are derived for dustmagnetoacoustic waves in magnehzed dust plasma The influence of charge fluctuationon dust waves is discussed for some dust plasma in space.

A STUDY ON TOPOLOGICAL FEATURE OF THE EQUATORIAL SPREAD-F UNDER THE EXISTENCE OF ACOUSTIC-GRAVITY WAVES

XIE Hong, XIAO Zuo, WANG Xianmin

1997, 17(4): 309-316. doi: 10.11728/cjss1997.04.309

Abstract(2071) PDF 460KB(892)

Abstract:
In this paper, a qualitative discussion and numerical calculations are made for thetopological characteristics of the nonlinear govehong equations of the excitations ofequatorial Spread-Funder existence of acoustic-gravity waves. The results show thatin detendning the pertUrbahon features of Spread-Fthe amplitudes of asoustic-gravitywaves take an important role. When the amplitude of acoustic-gravity wave is small,features of the equations' singularity are similar tOsituations without AGWs, i. e.,nonlinear resoluhons will finally stabilized to two fixed ponts, as the amplitude ofAGWs becomes larger, there will be a crihcal value. Above this value, soluhons showchaotic characterishcs, and Spread-Fwill have rich spectral components. When theamplitude of AGWs getting even larger than a second crihcal value, the soluhons ofthe system recovers from chaohc to Periodic and the features of solutions are mainlydetermined by AGWs as extemal driving souree.

THE VLBI TIME DELAY MODEL APPLIED TO THE OBSEBVATIONS OF THE OBJECTS IN THE SOLAR SYSTEM

PING Jingsong, YANG Zhigen, QIAN Zhihan

1997, 17(4): 317-321. doi: 10.11728/cjss1997.04.317

Abstract(1844) PDF 285KB(864)

Abstract:
When the general VLBItime delay model is appied for the observations of theodo obects in the solar system the systematical errors will be introduced. This kindof errors is estimated for both of the groun and space VLBI. In order to solve thisproblem. a new hme delay model with 1ps of Precision is suggested in BSfor thenear radio obectSobserved by the Earth's ground surface VLBIsites. Also, thepossibility for this model is analyzed.

THE DATA REDUCTION OF RADIO OBSERVATIONS WITH SUB-ARCSECOND RESOLUTION

SU Bumei, LI Yongshen

1997, 17(4): 322-328. doi: 10.11728/cjss1997.04.322

Abstract(1996) PDF 472KB(981)

Abstract:
An extragalaactic radio source -NGC 5929 is obeerved by MERLINand VLAat multiple frequencies. The radio images achieved a resolution of the sub-arcsecond.There are serious disturbanes of the phase in the visibility at 408 MHz, due to theatmospheric effects above the antenna of MERLIN In addition, MERLINconsists ofseven telescopes. The array missed some information in (u, v) plane and causeddifficulty for mapping. The self-calibration and clean techniques are used to improvethe dynamic range of the images. The Hubble space telescope made the photographsof NGC5929 by the Planetary camra. In order to compare the optical line emittinggas with the edo endning plasma The 1.6 GHz contour map is superimposed on the[OⅢ] image. The paper introduces the data reduction method for NGC5929.

THE RELATION BETWEEN LH SPIKELETS AND DENSITY CAVITONS IN OBSERVATIONS OF FREJA

HUANG Guanli, WAN Deyu, Domilique L. Q., Bengt H

1997, 17(4): 329-336. doi: 10.11728/cjss1997.04.329

Abstract(2021) PDF 486KB(952)

Abstract:
The plasma density dePlehons may be resulted from four mechanisms, evidencesof which are shown by the observations of FREJAsatellite. The density cavitonscaused by different mecheanisms may trap the dsent waves at low-hybrid freqdency.The lower-hybrid spikelets are observed with electwtatic and electromagnetic modes.It is suggested that the electric component of the elecromagnetic low-hybrid turbulenceis trapped by the density cavitons.

NUMERICAL MODELING OF THE IONOSPHERIC VARIATIONS OVER THE GREAT WALL STATION, ANTARCTICA

Zhu Minghua, Cao Chong, Wu Jian

1997, 17(4): 337-342. doi: 10.11728/cjss1997.04.337

Abstract(1830) PDF 413KB(2033)

Abstract:
The diurnal variations of the ionosphere over the deat Wall Station reveal theWeddell Sea Anomaly in the summer. In this paper, the diumal variations of f₀F₂ andhm are simulared by using a one-dimensional and hme-dependent theorehcal model.We studied the effects of the neutral wind and O⁺ flux on f₀F₂ and h_m and concludedthat one reason why simulated f₀F₂ are greater than measurements is the upperboundary values are overeshmated by IRI. In the last part of the paper, a method forobtaining the actual f₀F₂ and h_m is presented.

TURBULENCE SPECTRUM OBSERVED FROM A CHAFF ROCKET

WU Yongfu

1997, 17(4): 343-347. doi: 10.11728/cjss1997.04.343

Abstract(1653) PDF 319KB(923)

Abstract:
Spectrum of the venical velocity fluctuations for the height interval in which anenormously strong horizontal wind velocity and an extremely large wind shear areobserved indicates some qulte important fetas. (1) The spectrum shows two regions,one at lower frequencies has spectral slope of -1.65, which is close to -5/3 expectedin an inenial subrange, the other at higher frequencies has spectral slope of-7. 11,which is close to -7 expected in a viscous subrange. (2) The spectrum has abreakpoint which occurs at about 70m. This observation is in good agreement withthe inner scale calculated. (3) Tuthulence energy dissipahon rate obtained from thespectrum is about 0.087 W/kg, which is about an order of magnitud higher thanthose measured during the MAP/WINE campaign.

THE MEASUREMENTS OF MESOPAUSE TEMPERATURE BY THE SYNTHETIC SPECTRA METHOD

WANG Yongmei, WANG Yingiian

1997, 17(4): 348-352. doi: 10.11728/cjss1997.04.348

Abstract(1830) PDF 333KB(1192)

Abstract:
Amethod of calculating the synthetic spectra by using the comb function isproposed. By using a weighted leastsquare method to fit the synthetic spectra withthe observed spectra of OH(9,4) nightglow at Beijing suburb, the rotationaltemperature of mesopause is derived. The variations of the nightglow intensity andthe rotahonal temperature with time are analyzed.

A SPECIAL OSCILLATION OF THE MIDDLE ATMOSPHERE

MA Ruiping, ZHANG Feng, MU Xiangming

1997, 17(4): 353-359. doi: 10.11728/cjss1997.04.353

Abstract(1909) PDF 449KB(958)

Abstract:
Throuh the analysis of SAMStemperature data of the Nimbu S7 satellite, a specialoscillation of the zonal mean temperatUre superimposed on the seasonal variation, whosecharacter is to oscillate synchronously in the horizontal direction and to be the standingwaves in the venical direchon, is found It is proposed that this oscillation may be acharacteristic mode the atmosphere with the zonal wavenumber m=0 and meridionalwavenumber n=0, corresponding to the eigenfuntion P₀⁰, which is exhibited as a simplevertical motion of the atmosphere. The formation of the standing waves and the harmonicoscillation may te due to the existence of the reflective levels in the vertical direction.

OPTIMAL CONTROL OF STRETCHING PROCESS OF SOLAR WINGS ON SPACECRAFT

GE Xinsheng, LIU Yanzhu

1997, 17(4): 360-366. doi: 10.11728/cjss1997.04.360

Abstract(2541) PDF 452KB(1122)

Abstract:
The optimal attitud control problem of speecraf during the sbetehing Process ofsolar wings is discussed in mis paper Amathematical model of the systom isestabished by use of the mulhbody dynamics and oPtical control theory. An algorithmof contro for the stretching process is proposed, considering the nonhlonomic behavior of the system. The effectiveness of the apprach is shown by numerical simulation.

ATTITUDE STABILITY OF LIQUID-FILLED SATELLITE WITH FLEXIBLE APPENDAGE IN GRAVITATIONAL FIELD

CHENG Gong, LIU Yanzhu

1997, 17(4): 367-371. doi: 10.11728/cjss1997.04.367

Abstract(1832) PDF 301KB(927)

Abstract:
The atutude stability of an asymmetrical liqind-filled satellite with a flexible barin the gravitational field by using the Energy-Casimir method is discussed in presentPaper. Asufficient condihon of stability of the relative equllibritim of the rigidelashc- liquld system in the orbtal coordinates is obtained. It is shown that thestablity condihon for such a system has a formal idenhty with the condihon of arigid satellite in the gravitahoal field.

A NOTE FOR FORECASTING SOLAR FLARES ACCORDING TO PLANETARY TIDE FORCE

DONG Shilun

1997, 17(4): 372-373. doi: 10.11728/cjss1997.04.372

Abstract(2280) PDF 156KB(863)

Abstract:
In thes note it is pointed out that the probability of flare-occurrence at different heliographic longitudes is related to the planetary tide force. There is a maximum flare-occurringprobability on the maximum phase of the tide force and a sub-maximum occurring probabilityon the minimun phase. This could be used as a reference in forecasting solar flares.

THE RELATIONSHIP BETWEEN Li ISOTOPE ABUNDANCE IN INTERPLANETARY DUST PARTICLES AND THE EVOLUTION ORDEROF SOLAR NEBULA

XIE Ping, XU Ynlin

1997, 17(4): 374-376. doi: 10.11728/cjss1997.04.374

Abstract(1769) PDF 207KB(642)

Abstract:
⁷L/⁶Li in 11 interpanetary dust partcles (IDPs) is measured- The average valueis 11.88. This paper describes the relahonship betWeen ⁷L/⁶Li isotope abundan andthe evoluhon order of Solar Nebula before the formation of the solar system.

DYNAMICS AND CONTROL OF FLEXIBLE SPACE MANIPULATOR

GU Xiaoqin

1997, 17(4): 377-381. doi: 10.11728/cjss1997.04.377

Abstract(1874) PDF 316KB(966)

Abstract:
Equahons of motion of flexible space medpulator are described. The influence ofdeflechon of the medpulator on payload positioning error is discussed. The controlstrategy is also designed as to insure payload tracking of prescribed traectories.