空间科学学报

1994 Vol. 14, No. 3

Previous Issue | Next Issue

Select articles

Display Method:

Cover

SOME CHARACTERISTICS OF TIMING AND ENERGY SPECTRUM OF X-RAY PULSAR 4U 1538-52

Zang Zhi-yun, Hang Heng-rong

1994, 14(3): 169-176. doi: 10.11728/cjss1994.03.169

Abstract(2086) PDF 493KB(657)

Abstract:
The source 4U 1538--52 is one of the well-studied X-ray pulsars. 4 mediumenergy (ME) observations with EXOSATare processed and analyzed, in which 2observations are during the X-ray eclipsing. Combined with the results of the otherobservations, some analyses and explainations are given in this paper. The spin-downof the neutron star is continuing duering the observations. The energy spectrum isthe power law spectrum, the iron line is not seen after Tenma observations. It isassumed that the X-ray dips will occur when the neutron star is eclipsed by a foreground star, a late-type dwarf. The X-ray bursts which sustained about 1 hour areformed by the increasing mass exchange and could occur at the different orbit phase.And there seem to be an emission line at the energy near 1 keV, if it is a cyclotronline, the magnetic field of the surface of the neutron star would be 8.6(1 + z) × 10⁶T.

OH MASERS IN W33A

Zheng Xing-wu

1994, 14(3): 177-182. doi: 10.11728/cjss1994.03.177

Abstract(2215) PDF 387KB(834)

Abstract:
The circular polarization spectra in W33A are observed on emission from the ²Ⅱ_3/2 J=3/2, F=1→1 and F=2→2 transition of OH. The hydrogen density in the masing region is infered about 10⁷ cm^-3 in both the long thin tube and spherical maser,Apump rate of ～1(OH) cm^-3s^-1 is required in both geometries for the photon emission rate of ～10⁴⁶s^-1. The required pump efficiency is higher in the sphericalmaserthan in the thin tube.

EQUATORIAL SPREAD-F INITIATED BY ACOUSTIC-GRAVITY WAVES

Xiao Zuo, Xie Hong

1994, 14(3): 183-190. doi: 10.11728/cjss1994.03.183

Abstract(2435) PDF 445KB(794)

Abstract:
The basic equation discribing Spread--Finstability with the existance of acousticgravity waves in the ionospheric Fregion are derived and the numerical simulationsfor certain cases are conducted. The results show that the Spread-Fwill occur inlarge-scale wavelike structures under the conbined action of acoustic-gravity wavesand the Rayleigh Taylor instability in the equatorial Fregion. This Spread-Fis aquasi-periodic instability moving at certain velocity and at late;developing stage itwill form plumelike plasma density depletions (bubbles) which can rise well abovethe Fpeak and become tilt. The acoustic-gravity wave vector determines the tiltdirection of bubbles. All these results are in agreement with the main observationalcharacteristics. It is thought then that acoustic-gravity waves are not only one ofthe initial sources of large-scale Spread-F, but also play an important role on itswhole evolutions.

THE RELATION BETWEEN THE ONSET TIMES OF THE NEGATIVE PHASE OF IONOSPHERIC STORMS AND THE MAIN PHASE OF MAGNETIC STORMS AT MIDDLE LATITUDES

Wang Jing-song, Xiao Zuo

1994, 14(3): 191-197. doi: 10.11728/cjss1994.03.191

Abstract(2234) PDF 469KB(708)

Abstract:
In this paper, it is assumed that at high latitudes when the air of the auroraloval is heated and then the molecule enriched air rises during the magnetic stormmain phase. This kind of molecule enriched air moves toward middle and low latitudes due to diffusion and interaction with the background neutral wind. Where itarrives, the electron loss coefficient increases and therefore the negative ionosphericstorm occurs. Based on this, a simulation is conducted and the relation between theonset times of the negative phase of ionospheric storms and the main phase of magnetic storms is given. The problem about the "time forbidden zone" of the occurrences of the ionospheric storm negative phase is also discussed. The results of calculation agree rather well with those of statistics.

THE NONLINEAR INTERACTION OF FORCED ROSSBY WAVE PACKETS IN THE MIDDLE ATMOSPHERE I.THEORICAL ANALYSIS

Xiong Jian-gang, Yi Fan, Li Jun

1994, 14(3): 198-204. doi: 10.11728/cjss1994.03.198

Abstract(2294) PDF 489KB(1228)

Abstract:
The problem of the stability of the forced Rossby wave packets which are nonlinearly interacted resonantly in the middle atmosphere is examined analytically.The expression of the stationary state and the condition of the stability are given.When there is only one forced wave packet, if its lengthscale isn't between that ofthe other two, the forced wave will not translate its energy to the others in thestationary state, the others are exhausted by Rayleigh friction. But if the wavelengthof the forced wave is between the other two, the stationary state bifurcates to another stable one as the intensity of the forcing increasing to some value. After thebifurcation, the amplitude of the forced wave will not vary with the forcing, but itincreases with the atmosphere height, the energy increased is translated to otherwave packets eventually. When there are two forced wave packets, the system willtend to stationary states with nonzero wave amplitudes of all three wave. Moreresults will be given through numerical analysis.

A NUMERICAL SOLUTION OF THE DYNAMO EQUATION FOR THE GLOBAL IONOSPHERE

Xu Wen-yao, Xia Qing, Li Wei-dong

1994, 14(3): 205-209. doi: 10.11728/cjss1994.03.205

Abstract(2708) PDF 320KB(1270)

Abstract:
The two-dimensional hemispherical dynamo theory is based on the symmetry aboutthe equator, and has certain inherent theoretical shortcomings and limitations in application. In order to extend the dynamo theory to the globe, the assumption of thesymmetry about the equator is removed in present study, the boundary condition atthe north (or south) pole is also removed. In this way the conventional boundaryproblem becomes "boundary--free" one, which describes more reasonably the physicsof the dynamo process and would show some essential characteristics. For instance,this method can be used to study seasonal and UTvariations of the S_q currentsystem, as well as dynamo effects of the non-dipole magnetic field, all of which areasymmetric about the equator. The global current system obtained by using presentmethod for simple symmetric condition is same as that by using hemispheric symmetric dynamo theory. As for asymmetric condition, the current intensity, focus location, current direction and other characteristics show more complicated features, whichcan not be explained by hemispheric dynamo theory.

EFFECTS OF COMPOUND FACTORS OF SIMULATED WEIGHTLESSNESS (HDT-30°) AND NOISE ON THE NEUROENDOCRINE-IMMUNITY SYSTEM IN RATS

Yang Guang-hua, Wen Xiu-lan, Wang Bac-zhen, Qian Jin-kang

1994, 14(3): 210-213. doi: 10.11728/cjss1994.03.210

Abstract(2275) PDF 276KB(1156)

Abstract:
The results of the experiment show that the rats exposed to the suspension(HDT--30°) and the noise environment of 85 dB(A) for 10 days has a significantdecrease in lympocyte blastogenesis and interleukin--2 (IL2), a significant increase inthe content of plasma corticosterone, a tendency to be raised in the content of dopamine (DA) and noradrenaline (NA) in hypothalamus. These changes may be incoherence with stress alarm reaction. The indices mentioned above in the 85 dB(A)show a similar changes, but are less significant than that of the group which exposed to the noise and suspension. The function disturbance of the causes which makeastronauts suffering from infection diseases in space.

AN ANALOG COMPUTATION OF MEASURING SOLAR DIAMETER BY CCD ASTROLABE AND ITS ACCURACY ESTIMATION AND ANALYSIS

Xu Jin, Xu Jia-yan

1994, 14(3): 214-220. doi: 10.11728/cjss1994.03.214

Abstract(2605) PDF 458KB(964)

Abstract:
Based on the principle of measuring the solar diameter by CCD astrolabe, a method of reducing the data of the solar images is proposed and tested, and 8 frames of the solar images exposed on a CCD chip for each of three seeing conditions areyielded. Based on these frames of exposures, adopting digital image reduction technique, accuracy of measurement of the solar diameter is estimated and analysed. Theresults of simulating observation and computation show that CCD astrolabe couldmeasure the solar diameter with accuracy better than 0.05" for both the scheme ofa single image and the scheme of couble images.

CHAOTIC CHARACTERISTICS OF THE IONOSPHERIC PARAMETERS AND THE PREDICTABLE TIME SCALE

Jiang He-rong, Yang Zeng-yu, Yang Mei-Hua

1994, 14(3): 221-226. doi: 10.11728/cjss1994.03.221

Abstract(2082) PDF 396KB(884)

Abstract:
Using the phase space reconstructing method, taking the time series data ofionosphere to construct m-dimension phase space and to investigate the relationshipbetween phase points, as well as to extract the fractional dimension and Lyapunovindex, the chaotic features of there time series and the maximum time scale pridictable can be revealed.

THE DECONVOLUTION METHOD OF GROUND-BASED ATMOSPHERIC OZONE REMOTE SENSING

Xu Ji-yao, Wang Ying-jian

1994, 14(3): 227-232. doi: 10.11728/cjss1994.03.227

Abstract(2390) PDF 387KB(1044)

Abstract:
In this paper, a new method for atmospheric remote sensing from the ground isproposed. The nonlinear deconvolution method and reference effective instrumentfunction are used to increase the spectral resolution. The nonlinear least Squares method is used to retrieve the atmospheric ozone profile. This method can increasemeasurable altitude range of remote sensing and improve the precision of atmospheric ozone inversion obviously.

THE IMF AND ITS ASSOCIATED GEOMAGNETIC αα INDEX AND STORM

Zeng Xiao-ping, Lin Yun-fang

1994, 14(3): 233-236. doi: 10.11728/cjss1994.03.233

Abstract(2116) PDF 267KB(602)

Abstract:
The influences of the interplanetary magnetic field (IMF) total intensity Bandits sector boundary on the magnetic field of the Earth are investigated by examination of the maximum αα indices during geomagnetic storms. The stroms are classifiedinto three types according to their different linear'correlations between the IMFandthe αα indices. Each type of the storms has its characteristics in association with theappropriate solar wind parameters. There are two geomagnetic effects in response tothe two spiral IMFsector boundaries passing the Earth. It seems that the αα indexmay take the precedence over others in the study of solar--terrestrial couplings.

NUMERICAL PREDICTION OF GEOMAGNETIC ACTIVITIES

Zhou Xiao-yan, Tschu Kang-kun

1994, 14(3): 237-243. doi: 10.11728/cjss1994.03.237

Abstract(2454) PDF 446KB(855)

Abstract:
The recurrence of geomagnetic activities has provided the. possibility for the prediction. Aquantitative, computable. method--self--adaptive filtering, is introducedto forecast Kindex; its objective is, going with the filtering, to estimate and rectifythe model parameters (on--line) continuously by means of the new observations. Twoperiods July 14, 1984—Jan. 18, 1985 and Sept. 15, 1991--Mar.21, 1992 are selected for testing the method. The prediction precision is estimated by covariance(Cov) and standard variance (St). For the first period, Cov= 0.66, St = 4.74; thesecond is Cov = 0.79, St = 6.43. The results also indicate the significance of combining the various observations, forecaster's experience with the theoretical computations.

A SINGLE-FREQUENCY POSITIONING METHOD USING FIVE NAVSTAR FOR SATELLITE NAVIGATION

Song Mao-zhong, Wang Yong-cheng

1994, 14(3): 244-248. doi: 10.11728/cjss1994.03.244

Abstract(3397) PDF 406KB(748)

Abstract:
In this paper, a new single-frequency positioning method using five satellitesand algorithm of selecting these satellites are proposed, with which the propagationzenith time delay error can be estimated authomatically. Simulation results show that,when the source error is only due to ionospheric delay, the positioning error withthis method is less than that of the conventional positioning using four satellites, andis hardly different from the error of the differential positioning.