1998 Vol. 18, No. 1

Display Method:
LEVELS OF SOLAR SOFT X-RAY BACK GROUND AND ENHANCED EMISSIONS WITH IMPORTANCE X
WU Hongao, XU Fuying
1998, 18(1): 1-7. doi: 10.11728/cjss1998.01.001
Abstract(1640) PDF 504KB(928)
Abstract:
During the periods of January, 1986-December, 1992, 130 solar soft X-ray events with importance≥ X1 at 1- 8Å wavelengths reported and the corresponding background emissions are analyzed. And it is found that more than 90% of X-ray events with importance ≥X1 appeared at the level≥C1 of background emission. Such a statistical rule may be interpreted as the result that the nonthermal electrons accelerated by solar flare to heat chromosphere plasma.
THE HYBRID SIMULATION OF QUASI-PARALLEL COLLISIONLESS SHOCK
LU Quanming, WANG Shui
1998, 18(1): 8-14. doi: 10.11728/cjss1998.01.008
Abstract(2074) PDF 459KB(657)
Abstract:
The structure of quasi-parallel collisionless shock is numerically studied using one dimensional hybrid simulation. The results show that after upstream protons interact with quasi-parallel collisionless shock, a part of them are reflected and travel far upstream. This leads to the generation of ion beam instabilities which in turn excite large-amplitude right-hand polarized low-frequency resonant waves. These waves are convected back downstream by solar wind and gradually merge with the shock,in the meantime new waves are generated continuously in the upstream. This process is cyclical. For parallel collisionless shock, there exist the large-amplitude right-hand polarized low-frequency non-resonant waves in the downstream. Low-frequency waves in upstream are gradually enhanced while travelling downstream, finally exceed the old shock and form a new shock.
INTERACTIONS OF THE VORTEX INDUCED RECONNECTION PROCESSES IN PERIODIC MULTIPLE CURRENT SHEET SYSTEMS
SHEN Chao, LIU Zhenxing
1998, 18(1): 15-22. doi: 10.11728/cjss1998.01.015
Abstract(1864) PDF 568KB(877)
Abstract:
The vortex induced reconnection(VIR) processes in periodic current sheet systems with shear flows at near and supper Alfvén speed are investigated by using the two dimensional compressible magnetohydrodynamics(MHD) simulation method. The results show that, the VIR processes in the neignbouring current sheets can interact with each other, and their linear growth rate is enhanced and decreased for the cases of antisymmetric and symmetric modes, respectively.
A THEORETICAL MODEL OF THE MIDLATITUDE IONOSPHERE
ZHU Minghua, C. Taieb, CAO Chong, WU Jian
1998, 18(1): 23-31. doi: 10.11728/cjss1998.01.023
Abstract(1618) PDF 573KB(1047)
Abstract:
In the paper, a timeu-dependent and one-dimensional theorehcal model of the mid-latitude ionosphere is established by using the spectral method. The model takes account of major dynamic and photo-chemical processes in the mid-latitude ionosphere.It has the advantage of taking less computing time. We simulated the ionosphere above Wakkanai station in Japan. The results of the simulation are in good agreement with the measurements.
EFFECTS OF THE GEOMAGNETIC ACTIVITY ON THE IONOSMRIC MONTHLY MEDIAN f0F2 AND ON THE IRI PREDICTION PRECISION
WU Jian, SUO Yucheng, QUAN Kunhai
1998, 18(1): 32-38. doi: 10.11728/cjss1998.01.032
Abstract(1878) PDF 478KB(1068)
Abstract:
Vertical sounding data monthly median f0F2 from 1977 to 1986 at 9 Chinese ionospheric observatories in middle and lower latitude region is used in this paper to study the effects of the geomagnetic activity on the average behavior of monthly median f0F2 and on the IRI prediction precision. Data is grouped in two cases, one is for monthly averaged magnetic active index Ap < 15, the other for Ap≥ 15. Averaged diumal variations of monthly median f0F2 without considering season and solar activity shows that the bigger Ap is, the bigger averaged monthly median f0F2 value at all local time, and that the effects of the geomagnetic activity is more important at local noon and in the afternoon, and in lower latitude region. Averaged seasonal variations of monthly median f0F2 without considering local time and solar activity shows that averaged monthly median f0F2 value at higher geomagnetic activity is bigger than at lower geomagnetic activity during spring and summer. The positive deviation is up to 4MHz in March. And it is smaller than at lower geomagnetic activity during fall and winter. The negative deviation is up to 2MHz in September. Comparative study with the IRI indicates that during 0500-1000LT the IRl results are bigger than observations.The lower geomagnetic activity, the bigger the IRI deviation. During 1600-0400LT in lower latitude region, the IRI results are smaller than observations. The higher geomagnetic activity, the bigger the IRI deviation. During 1100- 1500LT the IRI results are between observations of higher geomagnetic activity and of lower geomagnetic activity. The total averaged IRI errors are bigger in higher geomagnetic activity than in lower. Maximum deviation of the averaged IRI errors from higher geomagnetic activity to lower is about 0.8MHz. The standard deviation of the IRI demonstrates an important latitudinal variation. In the lower latitude region south of Lanzhou to Haiou, The total standard deviation increases with the decrease of latitude.The standard deviation increases with the increase of the magnetic activity. In middle latitude from Lanzhou to Manzhouli, the standard deviation keeps stable when latitude increases, and it increases with the increase of the geomagnetic activity. An important conclusion of this study is that the effects of geomagnetic activity on the monthly median f0F2 are considerably important and that ignoring the effects is a main source of IRI errors.
THE NONLINEAR PROPAGATION OF GRAVITY WAVE PACKETS IN COMPRESSIBLE ATMOSPHERE
ZHANG Shaodong, YI Fan
1998, 18(1): 39-51. doi: 10.11728/cjss1998.01.039
Abstract(1711) PDF 610KB(2059)
Abstract:
In this paper, numerical simulation of nonlinear propagation of gravity wave packets with Gaussian distribution in isothermal and compressible atmosphere is presented by using 2-dimentional FICE scheme. The numerical analysis show that though there exists nonlinear reaction, during the propagation process, the phases of waves move downward, the wave packets and the wave-associated energy propagate upward. Wave-associated disturb velocities increase exponentially with the height and the reaction between the waves and the background leads to the enhancement of the mean flow. These agree well with the linear gravity wave theory. The propagation trace of gravity wave packets is consistent with the prediction of linear ray theory, but the average horizontal group velocity and vertical group velocity are obviously smaller than the results given from the linear ray theory. It indicates that the nonlinear process of gravity waves can change the propagation velocities of wave- associated energy. The simulation results show quantitatively that the effect of nonlinearity on propagation of gravity wave packets for the first time, it indicates that the definitions of dynamics of gravity waves given by the linear theory are reasonable.
A NUMERICAL STUDY ON THE SPATIAL AND TEMPORAL EVOLUTION OF INTERACTIONS OF GRAVITY WAVES PACKETS
ZHU Dan, YI Fan
1998, 18(1): 52-61. doi: 10.11728/cjss1998.01.052
Abstract(1692) PDF 659KB(1253)
Abstract:
A numerical model for studying the evolution of interactions among coherent gravity wave packets in a two-dimensional space is developed. With this model the complete evolution of interactions caused by the collision between two large-amplitude wave packets is revealed. Numerical results show that downgoing gravity waves can be excited by upgoing gravity waves through interactions. During the evolution process of these interactions, the energy budget of three wave packets and the intensity of interactions are localized. Since the spatial propagation is included, the interaction process is no longer Periodical and then a new characteristic time arises, which has completely different meaning compared with the previous one. This new characteristic time and the final developing level of interactions are determined not only by wave interaction coefficients and the initial amplitudes of wave packets, but also by wave packet spatial scales and the relative magnitude of wave group velocities.
CONTACT-IMPACT DYNAMIC ANALYSIS OF SPACECRAFT IN THE COURSE OF SPACE DOCKING
YU Dengyun, QU Guangji, ZENG Xin, WANG Ning
1998, 18(1): 62-68. doi: 10.11728/cjss1998.01.062
Abstract(1579) PDF 454KB(1303)
Abstract:
The contact-impact dynamics in the course of spacecraft docking is the basis of research and design of docking mechanism of manned-space vehicle. According to the docking mechanism of androgynous and peripheral type, a contact-impact dynamic model and an explicit expression of impact load are given in this paper by using the vector mechanics and visco-elasticity. The targeting calculation and statistical analysis of an engineering sample is used to illustrate the method, and a satisfying result is obtained.
REAL-TIME KINEMATIC ATTITUDE DETERMINATION OF AIRCRAFT USING GPS CARRIER PHASE
WANG Huinan, HE Feng
1998, 18(1): 69-74. doi: 10.11728/cjss1998.01.069
Abstract(1692) PDF 336KB(923)
Abstract:
The paper describes the basic idea of real-time attitude determination using GPS carrier phase and introduces a mathematical model for attitude determination system. The paper presents an effcient method for resolving single difference phase ambiguities and reveals the meanings of the physics by nature.
A SIMULATION STUDY ABOUT EFFECTS OF MICROGRAVITY ON CELLULAR MORPHOLOGY AND STRUCTURE OF RAT'S CARDIAC MUSCLE
YUE Ming, ZHANG Xiaoyou, WANG Gongzhi, DING Bai, ZENG Yuzhang, TAN Yingjun
1998, 18(1): 75-80. doi: 10.11728/cjss1998.01.075
Abstract(1901) PDF 536KB(1367)
Abstract:
A laboratory simulation is made to show the effects of microgravity on the cellular shape and structure of rat's cardiac muscle. The cell's cultural system is put into a simulated microgravity environment. It is found that cellular morphology changes from slim to round in optical microscope and cytoskeloton changes from columnar morphology to radial morphology through marked Actin in fluorescence microscopy. Cellular area of cardiac muscles becomes significandy decreased by 40% and cellular long-short axes ratio decreased by 70% through micromeasurement.
THE TEMPORAL PROCESSES OF THE SOLAR PROTON EVENTS AFFECTIG THE EARTH ENVIRONMENT
HUANG Yongnian, WANG Zhidan
1998, 18(1): 81-85. doi: 10.11728/cjss1998.01.081
Abstract(2065) PDF 354KB(1067)
Abstract:
The statistical relations between the arrival time, maximum time of proton events and the flare-associated longitudinal position are studied in detail by using data of solar flares and proton events from 1966 through 1992. It is concluded that the above two time processes are the shortest when solar flares are at longitudinal positions which are the footpoints of the large-scale interplanetary magnet field lines connecting with the earth. The result supports the two-stage diffusion model, which asserts that the solar flare protons propagate in the interplanetary space following the coronal transport.
AN ANALYSIS OF THE MILLISECOND FAST FINE STRUCTURES OF SOLAR RADIO BURSTS DURING SOLAR CYCLE 21,22
WANG Shulan
1998, 18(1): 86-90. doi: 10.11728/cjss1998.01.086
Abstract(1667) PDF 347KB(645)
Abstract:
In this paper, 285 fast events at 2545 MHz, 2645 MHz and 2840 MHz recorded during the 21st and 22nd solar activity cycles are analysed. Various kinds of the fast events are found during that period. It is found that the fast fine structures (FFS)observed during the two solar maxim are very different, for example, the discrete and isolated spikes, the clusters of the crowded spikes, the spikes superimposing on the noise background, and the phenomena of absorption occurring in solar cycle 21, and events with more narrow bandwidths, frequency drifts, polarization and the quasi-periodic oscillations occurring in solar cycle 22. In addition, the rate of FFS occurrence are also different for the two cycles. Some events associated with solar flares are analysed, too.
POSITIONAL DETERMINATION OF A STAR WITH RESPECT TO THE EPHEMERIDES OF URANIAN SATELLITES
PENG Qingyu, MAO Wei, YE Binxun
1998, 18(1): 91-93. doi: 10.11728/cjss1998.01.091
Abstract(1676) PDF 228KB(940)
Abstract:
This paper presents an observational routine to determine precisely the barycentric positions of the outer planets (Saturn, Uranus, and Neptune) by CCD observations. It is required according to the routine that the CCD observations are obtained with both a long-focus telescope which is used to observe some satellites of an outer planet and a meridian circle which works in a CCD drift scanning manner. Furthermore, the observations obtained with No. 1 CCD on 1-meter te1escope at the Yunnan Observatory is used to determine the positions of two faint stars with respect to the positions of the ephemerdes of Uranian satellites. The results show that the positional precision for each star is comparable to the best observations of Uranian satellites.
SEASONAL VARIATIONS OF LOW FREQUENCY WAVE OBSERVATIONS AT WUCHANG
HU Xiong, ZHANG Xunxie, HUANG Zerong, RUAN Xueqin
1998, 18(1): 94-96. doi: 10.11728/cjss1998.01.094
Abstract(1538) PDF 217KB(858)
Abstract:
The 11-years'LF phase data at noontime at Wuchang are used to analyse seasonal variations of the D region. The results show that the reflection height of LF in mid-and lower latitudes has a dominant annual variation with the minimum in summer and the maximum in winter, i.e. the electron density of D region is obviously higher in summer than that in winter, which is a little different from that in the mid-and high latitude ionosphere. The amplitudes and phases of this annual variation for each year are calculated. The day with zero degree phase is close to the winter solstice, which suggests that the main reason of the annual variation is the seasonal variation of the zenith angle. And the amplitude due to zenith angle variation is estimated in this paper.The fluctuations of amplitudes of annual oscillation show an interannual variability with little relation to the solar 11-year cycle, but seems to be modulated by a quasi-two year oscillation.