Abstract(0) [PDF 1570KB](0)
Abstract:
Ultra LEO spacecraft has become a hot research field for a wide range of application in military, remote sensing, scientific research, etc. Due to the special space environment of ultra-low orbit, many technical difficulties need to be solved, mainly focusing on atmospheric environment prediction, aerodynamic, aerothermal and so on. This paper introduces the typical mission of ultra LEO spacecraft, the main atmospheric model and inversion method, the aerodynamic design of ultra LEO spacecraft and the stability control method under aerodynamic interference, the aerodynamic thermal protective material and the variable switching technology of thermal insulation and heat dissipation. This review is helpful to promote the key technology research and test demonstration of ultra LEO spacecraft, turning the ultra LEO spacecraft from test mission to space application mission as soon as possible.
Abstract(7) [PDF 857KB](4)
Abstract:
During the nighttime, the 135.6nm spectral line is excited by the radiation recombination process of F region O+ and e- and the mutual neutralization process of O+ and O- in the ionosphere. There is a strong correlation between the intensity of the spectral line and the maximum electronic density of ionospheric F2 layer (NmF2). Based on the physical model in which the OI 135.6 nm emission is proportional to the square of NmF2, we establish a retrieval algorithm suitable for different longitude and latitude, local time, season and solar activity. In this paper, the critical frequency of ionospheric F2 region (foF2) was retrieved from 135.6nm emission observed by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on board the Defense Meteorological Satellite Program (DMSP), and then the estimated results were compared with the detection results of ground-based ionosonde. As the results show, during the high-solar activity year (2013), the data with relative error less than or equal to 20% accounted for 92.99%, and the average relative error was about 7.18%. During the low-solar activity years (2017), the data with relative error less than or equal to 20% accounted for 80.76%, and the average relative error was about 13.02%. Finally, we analyzed the difference of retrieval accuracy of the algorithm during the high and low solar activity years.
Abstract(20) [PDF 826KB](9)
Abstract:
With LEO mega satellites constellation coming into operation, the available spectrum resources are more overcrowded. To improve spectrum utilization, cognitive satellite communication technology composed of GEO relay satellites and LEO satellites has become an important choice. The most critical step in the cognitive satellite communication scenario is the spectrum sensing technology used to quickly determine the presence or absence of the primary user. Since most current spectrum sensing algorithms are model-driven, they rely heavily on the assumed statistical model for their detection performance, which makes it more difficult to model and deploy in variable satellite communication scenarios. In this paper, we firstly analyze the signal-to-noise ratio fluctuations during LEO satellite transit, and secondly propose a spectrum sensing algorithm combining bidirectional long short-term memory network and Bayesian likelihood ratio test for this variable channel environment. The algorithm does not require any a priori knowledge of PU signals and can automatically learn features from PU signal data and make decisions. Simulation results show that the proposed algorithm still achieves 83% detection performance at a signal-to-noise ratio of -14 dB and consistently outperforms convolutional neural networks, multi-layer perceptron, and model-driven energy detection-based algorithms.
Abstract(9) [PDF 1054KB](4)
Abstract:
Understanding the interplanetary propagation of solar storms is the foundation of space environmental forecasting and services. The visualization of numerical model results is an important method to analyze the propagation dynamics process and verify the validity of the model. In order to facilitate the visual analysis of the model results, a transfer function design algorithm for volume rendering of time-varying data(TVTF) is proposed. The algorithm is based on the KNN background subtractor method to extract images including motion regions and motion subsets, and then use frequency-tuned (FT) salient region detection algorithm to detect coronal mass ejection(CME) in motion area images, and according to the CME detection results, a color inverse mapping algorithm is designed to find the boundary threshold between the CME and the background. Finally, the transfer function is adaptively adjusted based on the threshold to realize the fast 3D visualization of CME in the motion region at each time step. The experimental results show that the transfer function can adapt to the numerical model results in static and dynamic backgrounds. Compared with the linear transfer function, the occlusion of the line of sight direction is effectively avoided, the change of relative momentum is intuitively and automatically displayed, and the evolution process of CME in interplanetary space is traced. The extraction of local regions reduces data redundancy, and the process of adaptively adjusting the transfer function by automatically analyzing the data with the help of algorithms avoids the inefficiency of manual adjustment.
doi: 10.117282022-0016
Abstract(14) [PDF 1213KB](12)
Abstract:

Responses of the middle and upper atmospheric (80-100 km ) wind to geomagnetic activities have been investigated using neutral wind data from 2012 to 2018 years, which were observed by Mohe, Beijing and Wuhan Meteor radars. Daily averaged wind data for geomagnetic quiet condition (Kp ≤ 2) and geomagnetic disturb condition (Kp ≥ 4) were chosen for comparison, and the variation characteristics of wind during geomagnetic disturbances were obtained. The observations show that the influence of geomagnetic activity on zonal wind varied with seasons and latitudes. For zonal wind, the effect of geomagnetic activity at higher latitudes tended to be more westerly wind in the upper mesosphere and more easterly wind in the lower thermosphere, and the differences between disturbed and quiet conditions were on the order of 3 m/s; while for the lower latitudes, it tended to be more easterly wind in the 80-100 km region, and the influence were about 5 m/s. In spring, the three stations had similar tendencies, and had no latitude differences. But the easterly wind in the middle atmosphere became stronger with the decrease of latitude in summer/winter. The effect of geomagnetic activities on the meridional wind had seasonal differences. The influence of geomagnetic activities in spring and winter was stronger than that in summer and autumn. In winter, the effect of geomagnetic activity on the meridional wind in middle and low latitudes was stronger than that in higher latitudes. According to the calculation results, the influence on zonal wind was about 5 m/s to 10 m/s, and on meridional wind was about 3 m/s to 5 m/s. The impact of geomagnetic activities on MLT wind can penetrate down to about 80 km. At this height, the influence on zonal wind was the strongest in spring, reaching 8 m/s, and on meridional wind was the strongest in spring/winter, reaching 5 m/s.

doi: 10.117282022-0014
Abstract(20) [PDF 1359KB](7)
Abstract:

The prerequisite of target detection and tracking is to model and represent the target based on multi-dimensional features extracted from the target region. The traditional target feature extraction needs to connect the target region first and then must calculate the target feature, which has still room for improvement in real-time. An advantage of the new method based on the synchronous calculation of pixel-connected domain markers and target features is that the target features can be output when the target region is connected. The process establishes a feature transfer mechanism, creates a marker table, a marker mapping table, and a feature attribute table simultaneously when scanning images, and uses the marker mapping table to associate the marker table and the feature attribute table. The marker merging and feature attribute transfer calculation are performed synchronously at the time of region adjacency, which ensures the real-time target feature extraction. As a result, the method proved to be effective because of an implementation scheme based on an FPGA system design. Simulation test results show that this method has several outstanding features: the time of connected domain markers is close to the theoretical minimum; the storage of images utilizes the circular buffer with low resource consumption; marking and computation are processed in parallel flow to improve detection and tracking efficiency; multi-target features are tested and verified to be accurate, which can effectively support subsequent target tracking detection; and it has theoretical and practical values.

Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
2016, 36(4): 476-480.   doi: 10.11728/cjss2016.04.476
Abstract(850) [PDF 946KB](7)
Abstract:
The linear stability of thermocapillary convection in annular pools is studied through the Chebyshev-collocation method. As Pr=6.8, the ratio of outer radius and inner radius is 0.5, and the range of aspect ratio A is from 0.25 to 1.4, numerical results show that the critical mode of the flow are oscillating. The critical Marangoni number, critical wave number and oscillating frequency decreases as A increases. Energy analysis shows that surface tension in the radial and azimuthal directions plays a leading role in the variation of perturbation energy. And the interaction between perturbation flow and the basic flow is small compared to the two former terms. We find out that the work done by the surface tension in the radial direction reaches minimum were analyzed, while the work done by the surface tension in the azimuthal direction and the interaction between the perturbation flow and the basic flow reach maximum, as A=0.8.
2015, 35(3): 315-323.   doi: 10.11728/cjss2015.03.315
Abstract(1066) [PDF 1816KB](2)
Abstract:
Sprites are the transient luminous events above very active thunderstorms and are the direct evidence of the energy in troposphere coupled to the upper atmosphere. The emissive spectrum study is the important means to understand the energy injected into upper atmosphere and regional ionization, the electron energy distribution during the whole event. These parameters are useful for the study of sprites' physical mechanism, in addition as a kind of natural atmospheric luminous phenomenon, the emissive spectrum study is useful for providing important information to the research of atmospheric radiation background information. Based on the Boltzmann Equation to calculate the time evolution of the electron energy distribution function in a mixture of partially ionized gases with an applied electric field, the paper calculated the spectral intensity in typical emissive band for sprites. Simulation results show that the emissive intensity is more intensive with more intensive E/N and the emissive spectrum is from far ultraviolet to near infrared.
2019, 39(3): 399-406.   doi: 10.11728/cjss2019.03.399
Abstract(2626) [PDF 2123KB](2)
Abstract:
Based on the finite time control, the trajectory tracking and flexible vibration suppression of a free-floating space robot system with two flexible arms and elastic base are discussed. Because of the multiple dynamic coupling relationship between the elastic base and the two flexible arms, the system is a highly nonlinear system. Firstly, the connection between the elastic base and the first arm is regarded as a linear spring, and the dynamic model of the system is derived from the Lagrange equation of the second kind and the assumed mode method. Secondly, by applying the two time-scale assumptions of singular perturbation theory, the system is decomposed into a slow subsystem which represents the rigid motion and a fast subsystem which represents the elastic base and two arms vibration. For the slow subsystem, a finite-time controller based on the nominal model is designed to realize the rigid desired trajectory tracking. Due to the finite time convergence property of the integral sliding mode surface, it has faster convergence speed and stronger robustness than the traditional asymptotic convergence control method. For the fast subsystem, the linear quadratic optimal control method is adopted to suppress the vibration of the elastic base and the two flexible arms simultaneously. Lyapunov theory is used to prove that the proposed control algorithm can enable the tracking error converging to the origin within a finite time. Finally, the simulations verify the effectiveness of the control method.
2019, 39(3): 373-380.   doi: 10.11728/cjss2019.03.373
Abstract(2666) [PDF 3359KB](2)
Abstract:
The on-board VHF system is an important part of the SVOM satellite. It provides a quasi-real-time VHF-band information access channel for the location information and the important data of the scientific target which is detected by payloads. In this paper, the design of VHF system on-board SVOM is introduced. The equipment design, software design and modulation algorithm design are described in detail. SVOM VHF system is the first application of 4CPFSK modulation in VHF band for spaceborne data transmission in China. Test results show that the implementation of the VHF system can meet the application requirements of the satellites and provides a solution for the real-time transmission of important data of space science satellites.
2019, 39(3): 295-302.   doi: 10.11728/cjss2019.03.295
Abstract(2620) [PDF 1514KB](2)
Abstract:
As arriving at the Earth, Interplanetary Coronal Mass Ejections (ICME) will interact with the Earth's magnetosphere and cause geomagnetic storms. The ICME event set is obtained by Richardson and Cane's Near Earth ICME list, and the input features are extracted based on interplanetary solar wind and magnetic data during ICME disturbance. A total of 483 ICME events from 1996 to 2006 are chosen in this study. 13 magnetic and kinetic features are finally selected for the training of the machine learning model. Rank of each feature's Fisher score indicates that the duration of the south-directed interplanetary magnetic field that is larger than 10nT and the increase of solar wind speed at the upstream shock or wave disturbance is closely related to the geoeffectiveness of ICME events, which is consistent with those former statistical results. The trained Radial Basis Function Support Vector Machine (RBF-SVM) can determine whether an ICME event could trigger moderate or stronger geomagnetic storms (Dst ≤ -50nT) effectively with an accuracy of 0.78±0.08. The results show that RBF-SVM can be used as a powerful tool in further analysis, and the better prediction of the geoeffectiveness of ICME will be obtained.
2019, 39(3): 310-315.   doi: 10.11728/cjss2019.03.310
Abstract(2555) [PDF 3071KB](4)
Abstract:
Based on three types of ICME-driven magnetic storms, including fierceness magnetic storm (SA type), strong magnetic storm (SB type) and delayed main phase storm (SC type) from 1995 to 2004, temporal superposition of the solar wind speed, the electric field EK-L, the interplanetary magnetic field and the auroral hemispheric power at the 1AU are conducted, and compared with the -vBz coupling function and the Newell coupling function respectively. The results show that there is a relative quiet period of the solar wind, auroral hemispheric power, interplanetary magnetic field and magnetic layer in the early stage of ICME arrival. However, the background solar wind speed, the southward component of the interplanetary magnetic field and the auroral hemispheric power of the SA magnetic storm are higher than those of the other two magnetic storm types. It indicates that the large coronal mass ejection has an effect on the interplanetary magnetic field, the background solar wind, and HP before the ICME arrives. After the rapid start of the magnetic storm, the low slope, delayed peak of the EK-L electric field of SC type magnetic storm and the northward component enhancement of the interplanetary magnetic field are the manifestations of the main phase delay of the magnetic storm.
2019, 39(3): 283-294.   doi: 10.11728/cjss2019.03.283
Abstract(2819) [PDF 3678KB](2)
Abstract:
A Meteoroid is a small rocky or metallic body in the space. In the solar system, most meteoroids are fragments from comets or asteroids. In the space between Earth and Mars, the speed of meteoroid ranges from 24.13km·-1 to 42.2km·-1. The high speed meteoroid may cause catastrophic damage to Mars probes. In this paper, the meteoroid environment models for the flight from Earth to Mars and the flight in the near-Mars orbits are established respectively. The meteoroid environment models are established based on the zodiacal light observations by the space probes Helios I and Ⅱ, and the observed orbital parameters of comets. The assessment method of meteoroid impact risk for the Mars orbiter mission is also established using the finite element method. A Mars probe with relative anomalous shape is proposed, and the meteoroid impact risk of this assumed Mars probe is predicted for demonstration purpose.
2019, 39(3): 316-325.   doi: 10.11728/cjss2019.03.316
Abstract(2870) [PDF 2941KB](1)
Abstract:
During the recovery of a magnetic storm, the relativistic electrons with MeV energy diffuse from the outer radiation belt to geosynchronous orbit. The electrons which energy are larger than 2MeV could penetrate the surface of satellites and accumulate inside them. Such an electron flux effect could cause satellites to be unable to function properly or to fail completely. Relativistic electrons change very rapidly during the magnetic storm and are very non-stationary. These effects are reduced by empirical mode decomposition method. Data in 2008-2009 are used as the training set, and data in 2010-2013 are used as the testing set. The result shows that the average prediction efficiency of the testing set is 0.81. The solar activity is complex in 2013, and the prediction efficiency is up to 0.81. The prediction efficiency of electron flux has been greatly improved by using empirical decomposition method.
2019, 39(3): 303-309.   doi: 10.11728/cjss2019.03.303
Abstract(2687) [PDF 1659KB](1)
Abstract:
The transport time is defined as the interval time between the occurrence of CME and the maximum value of the geomagnetic storm. In view of the 89 CME-Dst events collected from 1997 to 2015, the impact of CME speed, energy, and flare type on the transport time is analyzed. Using the non-linear fitting and the nonlinear regression of the Support Vector Machine (SVM), the Curve Fitting (CF) model and the Support Vector Machine (SVM) model for the CME transport time are built. In these models, 62 CME-Dst events during 1997-2006 are used as model input, and the remaining 27 CME-Dst events are used to test the model prediction. The results show that the prediction accuracies both of CF model and SVM model reach at about 85.2%, and the average absolute error of CF model is 13.77h while the SVM model is 13.88h. Comparing with the ECA model (its prediction accuracy is 77.8%, and the average absolute error is 14.55h), the accuracy of these two models is higher and the error is smaller than that of the ECA model. Therefore, CF model and SVM model can predict accurately the geomagnetic storm explosion with 1~5 days in advance.
2019, 39(3): 349-353.   doi: 10.11728/cjss2019.03.349
Abstract(2898) [PDF 1177KB](6)
Abstract:
In this paper, the problems about the principle and accuracy in the experiments of space gravitational redshift are analyzed. Firstly, according to Einstein Equivalent Principle (inertial force is equivalent to gravity), the main part of Earth's gravity inside the spacecraft is cancelled out by inertial force, so that the microgravity inside the spacecraft is much smaller than the gravity at its orbit. For this reason, the gravitational potential of the space borne clock should be taken as an effective gravitational potential corresponding to the microgravity. However, in Ref.[4] (GP-A experiment) and Ref.[5] (Radio astron satellite program), the gravitational potential of the clock is simply taken as the gravitational potential at the orbit. Secondly, testing the relativistic redshift requires a comparison between theoretical prediction and experimental measurement. The accuracy of this test is determined by the larger error. Therefore, if improving just the experimental precision but not the accuracy of the Earth Gravitational Model, then the test accuracy cannot be improved.
2019, 39(3): 381-387.   doi: 10.11728/cjss2019.03.381
Abstract(2597) [PDF 2788KB](5)
Abstract:
Atomic clock, as an important part of the navigation satellite, provides high-accuracy and high-stability time frequency source for the satellite. For the continuity and stability of atomic clock operation in orbit, the satellite thermal control system should provide a suitable temperature environment for it. In this paper the thermal control design and the control algorithm of atomic clock are introduced, and the results of thermal simulation and tests based on the atomic clock thermal control for the navigation satellite are provided. Temperature data in orbit show that the thermal design of cabin for atomic clock is suitable. Thermal simulation results and the tests are effective. In addition, the temperature of atomic clocks in orbit meets the requirement and is nearly one order of magnitude better than that of the indicator.
2019, 39(3): 365-372.   doi: 10.11728/cjss2019.03.365
Abstract(2361) [PDF 2733KB](4)
Abstract:
As a passive measurement method, the ground-based photoelectric observation is not limited by the equipment on the satellite and can be used to measure most of Geostationary Earth Orbit (GEO) targets above the station. The ground-based photoelectric observation has the advantages of low operating cost, strong intuition and high measurement precision, hence it can play an important role in monitoring the GEO targets. In order to evaluate the actual monitoring ability for GEO targets based on the photoelectric telescope at one single station, observation experiments of 3 Beidou GEO satellites are carried out by 1.56-meter telescope with CCD drift-scan photoelectric technology of Shanghai Astronomical Observatory. The external precisions are estimated by the precise ephemeris of the satellites. The results show that the accuracy of the celestial positioning of the GEO satellites is better than 0.3" in both azimuth and elevation. In the case of single observation pass, although the accuracy of orbit prediction is low, the orbit determination accuracy during observation arc is better than 100m. The effect of orbit improvement based on multi-pass of observations is obvious. In the absence of orbit control, the orbit determination accuracy is better than 50m, and the prediction precision of extrapolating to 4-day is about the order of hundreds of meters. In addition, the accuracy of the orbit prediction of the GEO target in the case of different observation time span is quantitatively evaluated, which can provide the reference for the practical application of the CCD drift-scan photoelectric telescope at one single station.
2019, 39(3): 388-398.   doi: 10.11728/cjss2019.03.388
Abstract(2721) [PDF 1863KB](5)
Abstract:
Momentum wheel as a key actuator for satellites, its reliability and life span directly affect the success or failure of satellite missions in orbit. For the life prediction and analysis of momentum wheel products, due to the limited number of samples, long test cycle and high cost, it is impossible to obtain enough life sample data. Therefore, combined with engineering experience and existing ground life test data, the Wiener process degradation model is used to model the reliability of the momentum wheel product, and its life expectancy is estimated and analyzed. The results show that this model provides an effective method for predicting the life of a momentum wheel and is suitable for life prediction and analysis of high reliability, long life products.
2019, 39(3): 342-348.   doi: 10.11728/cjss2019.03.342
Abstract(2795) [PDF 4015KB](4)
Abstract:
In order to evaluate the global distribution of atmospheric neutron at 0~100km altitude for real time, the propagation of cosmic rays in the geomagnetic field and the atmosphere is analyzed. By using the TSY05 and MAGNETOCOSMICS model, the real-time calculation of global geomagnetic cut-off rigidities with 1h resolution is realized. The spherical shell geometry model is established at intervals of 1km using NLRMSISE-00 model, and the spectrum distribution of secondary particles generated by different particles is calculated by the Monte Carlo simulation techniques, namely, the Geant4 toolkit, then an atmospheric neutron database is created. Compared with EXPACS model, the validity and reliability of the database are verified. Based on the observed or predicted space environment parameters, the energy spectra of the cosmic ray and the solar proton event in the synchronous orbit are calculated, and the effective vertical cut-off rigidities in function of latitude and longitude at the altitude of 100km. The atmospheric neutron and effective dose are calculated by using linear interpolation per hour.
1995, 15(4): 326-332.   doi: 10.11728/cjss1995.04.326
Abstract(2023) [PDF 560KB](2)
Abstract:
The relationship among solar activity,the sea temperature in the Kuroshio region and the flood and drought in the Middle Reach of the Yangtze River (MRYR)is investigated by using 30 years'data of solar activity,the sea temperature in the Kuroshio region and the rainfall in the MRYR. Results show that the rainfall in the MRYRis obviously controlled by the interannual and seasonal variations of solar activity and the sea temperature in the Kuroshio region.The solar 10.7cm radiation flux is taken as the index of solar activity and the interannual fluctuation curve of the difference of F10.7 between winter and summer oscillates with a period of about 11 years.The flood years(or drought years)frequently occurred when the positive part (or negative part and odd point) of the curve appeared 3 years ago and the last year lay in the peak (or valley,or near zero point)of the seasonal variation curve of the sea temperature in the Kuroshio region.According to these features, the solar activity data in the previous two years and the sea temperature data in the Kuroshio region before this spring can be used to analyze the trend of flood or drought in the MRYRin the coming summer.
2019, 39(3): 326-341.   doi: 10.11728/cjss2019.03.326
Abstract(2706) [PDF 10967KB](1)
Abstract:
Using the temperature profiles between 30°N and 40°N latitude observed by COSMIC satellites from 29 December 2006 to 3 January 2008, the disturbances and potential energy (Ep) of Gravity Waves (GWs) in lower stratosphere are calculated by vertical running windows method, double-filter method and single-filter method, respectively. The altitude and longitude distributions, and multi-time scale variations of these parameters are obtained. The spatial characteristics of background temperature and horizontal wind fields are analyzed to investigate the possible origins of GWs. The disturbances and potential energy (Ep) of GWs in lower stratosphere obtained by the above three methods are compared. The results are as follows. The errors of GW perturbations calculated by vertical running windows method are relatively large, because it can only remove the disturbances with large vertical scales, while can not remove small vertical scales in derived GW disturbances. The double-filter can well suppress both large-scale background and small-scale disturbances in temperature profiles. GW disturbances obtained by a single-filter does not include large vertical scale background, but still contain some small vertical scale disturbances. The double-filter method cannot obtain altitude variations of Ep, while the single-filter method can give altitude variations of monthly averaged Ep. The relationships between GWs' parameters (including disturbances and Ep) and background temperature and horizontal wind fields are revealed.
2019, 39(3): 275-282.   doi: 10.11728/cjss2019.03.275
Abstract(2690) [PDF 1571KB](0)
Abstract:
With the development of technology, space weather has an increasingly impact on global technology infrastructure such as power systems, communication and navigation systems and aerospace assets. Humans need to strengthen their understanding of space weather events, improve space weather forecasting capabilities, and optimize infrastructure designs to mitigate the impact of space weather on society. Based on these requirements, the Committee on Space Research (COSPAR) of the International Council for Science (ICSU) and the International Living With a Star (ILWS) Steering Committee jointly established an expert group to study and develop a global road map for 2015-2025 on space weather. This paper introduces and interprets the roadmap and discusses the implications of the roadmap for the development of space weather in China.
1981, 1(1): 41-46.   doi: 10.11728/cjss1981.01.041
Abstract(1815) [PDF 499KB](3)
Abstract:
In this paper we have studied the possibility to identify different types of the magnetopause discontinuities by means of the characteristics of the discontinuities of the magnetic fields, teh bulk flow velocities and the thermaldynamic parameters.This method itself is independent of the normal directions on the magnetopause.The analysis shows that this method may be used to identify several types of the discontinuities which may occur at the magnetopause.
2019, 39(3): 354-364.   doi: 10.11728/cjss2019.03.354
Abstract(2708) [PDF 5059KB](4)
Abstract:
2014, 34(6): 881-886.   doi: 10.11728/cjss2014.06.881
Abstract(1026) [PDF 633KB](0)
Abstract:
The dynamic equations of a Tethered Satellite System (TSS) with elastic tether were established. This model was linearized at the equilibrium position, and the influence of random perturbation on TSS was considered. In order to fulfill the station-keep control of the TSS along orbits, by integrating Kalman filter with the optimal state feedback control, a control scheme based on the 2nd Young Engineers' Satellite (YES2) project was proposed. Finally, simulation analyses based on the models with considering elasticity and neglecting elasticity were made respectively. Simulation results show that the system under proposed law has good anti-ja mming performance. Besides, the tether tension changes smoothly and its amplitude is small, so that the TSS has superior reliability and security. And with the decrease of stiffness, the tether longitudinal vibration increases, which could provide ideas for selecting the appropriate tether material.
2015, 35(3): 368-380.   doi: 10.11728/cjss2015.03.368
Abstract(929) [PDF 2338KB](2)
Abstract:
The main purpose to use Ethernet in spacecraft is to take advantage of its flexibility to meet the requirement of communication access convenience, simultaneously take into account that Ethernet has high bandwidth and data rates, and expect that it has both real-time and deterministic in control field. Looking for some real time network is the priority of the spacecraft using Ethernet. The deterministic scheduling mechanism of communication and transmission characteristics of real-time Ethernet has become a main determination of whether the Ethernet can meet the demand of spacecraft network traffic characteristics. According to the analysis of data communication characteristics in spacecraft, and comparison of real-time Ethernet communication scheduling strategy, the real-time Ethernet applied in spacecraft should has time synchronization, strong real-time, deterministic, high-bandwidth, containing multiple data types, dual redundant channels, meanwhile it is compatible with standard Ethernet.
2008, 28(2): 114-122.   doi: 10.11728/cjss2008.02.114
Abstract(2472) [PDF 4723KB](1)
Abstract:
The effects of Hall current on the reconnection dynamics and wave behavior are numerically studied in this report. The notable reductions in the openness of outflow region and the reconnection rate are shown as Hall effect weakens. The time series of the out-of-plane magnetic field By and the velocity components vx, vz in the (x, z) plane at the given points are transferred into the power spectra by the Fast Fourier Transformation (FFT) for the cases with various intensive Hall terms. Using the Minimum Variance Analysis (MVA) on E, the propagation directions and the polarized features of waves are determined. It can be found that there exists the whistler wave with the typical features near the magnetic separatrices in the case of the stronger Hall effect and the wave signature weakens substantially as the intensity of Hall effect is reduced. These results indicate that Hall effect has an important influence on the reconnection dynamics and plays a crucial role in generating the whistler-mode wave and fast reconnection rate. Besides, there is a positive coherency between the amplitude of whistler wave and the field-aligned current Jp in the plane near the magnetic separatrices in the case with the strong Hall term. It demonstrates the closed linkage between the whistler wave and Hall effect on the other hand.
2015, 35(4): 381-392.   doi: 10.11728/cjss2014.04.381
Abstract(1376) [PDF 5318KB](2)
Abstract:
Through Fourier transferring of data from the planetary synodic index, it is found that the year, 10-year, 100-year, 1000-year, 10000-year and 100000-year scales of cycles have 10n multiple relationship. More interestingly, if we set the most significant period (4.96488a) on the year scale as the unit time step and put it into the equation of planetary synodic index, 2400 years cycle would be determined stably. On this basis, 2400 years cycle can be also assembled to form 100000 years and 400000～410000 years cycles of the Sun's orbital motion. This is helpful to unveil the relationship between the Sun's orbital motion and solar activity, and is significant to discuss the mechanism of climatic variation on the thousand years and orbital scales.
2015, 35(4): 424-437.   doi: 10.11728/cjss2015.04.424
Abstract(916) [PDF 927KB](3)
Abstract:
In order to describe accurately ion velocity distribution in the auroral ionosphere, the relaxation collision model and the Maxwell molecule collision model is used to describe ion-neutral collisions of Boltzmann equation respectively. The expressions of the ion velocity distribution for 13-moment approximation based on the Maxwell and for 16-moment approximation based on the bi-Maxwell can be obtained by solving the transport equations of the Maxwell molecule collision model and the relaxation collision model respectively. According to Sheffield's theories, the incoherent scatter spectra are calculated using the ion velocity distribution of 13-moment approximation and 16-moment approximation for the relaxation collision model and the Maxwell molecule collision model respectively. Finally, the comparison of results of the incoherent scatter spectra between Maxwell molecule collision model and relaxation collision model are given. It is found that, the Maxwell molecule collision model is better than the relaxation collision model to describe the interaction between ion and neutral component in the ionosphere E layer. The 16-moment approximation is better than 13-moment approximation to describe the ion temperature anisotropy due to increased electric field.
1985, 5(3): 161-167.   doi: 10.11728/cjss1985.03.161
Abstract(1649) [PDF 393KB](5)
Abstract:
The curvature radiation resulting from cosmic monopole is investigated in detail. It is shown that there are suppressed effects for cosmic plasma on the curvature radiation of monopole.
2014, 34(5): 505-515.   doi: 10.11728/cjss2014.05.505
Abstract(1072) [PDF 13448KB](2)
Abstract:
In 1957, the launch of the first artificial satellite ushered in a new era for modern space science.The past 50 years' developments in China's space science have witnessed many major missions, and substantial progress has been achieved in space science study, exploration technology as well as experiment technology. Strategic Priority Program on Space Science was officially started in 2011. Through both self-developed space science missions and those with international cooperation,it is expected that the innovative breakthroughs will be realized, leapfrog development of related high-tech will be achieved to establish the important strategic status of space science in national development. To sum up, the implementation of the Strategic Priority Program on Space Science will definitely promote the rapid development of China's space science endeavor, making contributions to China's development and the progress of human civilization.
2003, 23(3): 197-204.   doi: 10.11728/cjss2003.03.197
Abstract(2144) [PDF 752KB](7)
Abstract:
2017, 37(6): 649-658.   doi: 10.11728/cjss2017.06.649
Abstract(946) [PDF 1047KB](0)
Abstract:
There were totally 128 Solar Proton Events (SPEs) from 1997 to 2016. Their peak flux ranges are from 10pfu to 99pfu, 100 to 999pfu, 1000 to 2999pfu and greater than 3000pfu, and the percentage is 55.15%, 27.94%, 9.56% and 7.35% respectively. The results show that SPEs with different peak flux have different asymmetry. The SPEs with peak flux ranged from 1000pfu to 2999pfu have the largest asymmetry, while those with peak flux greater than 3000pfu have smallest asymmetry. In Solar Cycle 23, the SPEs mainly occurred during the period from the first peak to the second peak and after the second peak of the smoothed monthly mean sunspot numbers. In Solar Cycle 24, the SPEs mainly occurred during the period before maximum of smoothed monthly mean sunspot numbers.
2018, 38(1): 88-93.   doi: 10.11728/cjss2018.01.088
Abstract(1417) [PDF 1338KB](3)
Abstract:
To realize the application of geomagnetic navigation on the low orbit satellite, the complexity, enormous calculation, poor real time ability of traditional Gaussian spherical harmonica function should be solved before being used to calculate the geomagnetic vector. A geomagnetic field approximation function, Geomagnetic Field Approximation Functions (GFAF), is proposed to replace the spherical harmonic function. Dipole model under a pseudo-centers is utilized to replace the main geomagnetic model in GFAF method. And the coefficient of pseudo-center of different latitude-longitude grid is obtained by polynomial fit method. Finally, the geomagnetic field vector of any position can be achieved using different interpolation algorithm. A simulation test is carried out under the condition that the increment of latitude and longitude is 0.5° and the orbital height is from 300 to 500km. The results show that the navigation accuracy of GFAF method is the same to that of geomagnetic field model. However, GFAF method effectively decreases the cost of computing and and improves the calculation efficiency.
2014, 34(5): 565-604.   doi: 10.11728/cjss2014.05.565
Abstract(1035) [PDF 432KB](0)
Abstract:
Solar transients and their related interplanetary counterparts have severe effects on the space environments of the Earth. Therefore, the research of solar corona and interplanetary physics has become the focus of study for both solar and space scientists. Considerable progress has been achieved in these aspects by the solar and space physics community of China during 2012-2014, which will be given in this report. The brief report summarizes the research advances of solar corona and interplanetary physics into the following parts: solar wind origin and turbulence, coronal waves and seismology, solar eruptions, solar energetic particle and galactic cosmic ray, magnetic reconnection, Magnetohydrodynamic (MHD) models and their applications, waves and structures in solar wind, propagation of ICMEs/shocks and their arrival time predictions. These research achievements have been achieved by Chinese solar and space scientists independently or via international collaborations.
2014, 34(5): 518-524.   doi: 10.11728/cjss2014.05.518
Abstract(1553) [PDF 6392KB](2)
Abstract:
With the complete success of the 2nd stage of Chinese Manned Space Program (CMSP), several science researches have been performed on Tiangong-1 experimental spacelab, which was docked with three Shenzhou spaceships one after another. The China's real spacelab, Tiangong-2 will be launched in 2015, docked with a Shenzhou spaceship soon. After six months, it will be docked with the first Chinese cargo ship (Tianzhou-1). More space science researches, involving with space biology, fluid physics, fundamental physics, materials science, Earth science, astronomy and space environmental science, will be operated on Tiangong-2 spacelab, and crewed and cargo spaceships. Furthermore, the considerable large-scale space utilization of Shina's Space Station is planned. The research fields include yet not limited to space medicine and physiology, space life science and biotechnology, fluid physics and combustion in microgravity, space material science, and fundamental physics in microgravity, space astronomy, Earth science, space physics and space environment utilization, technology demonstration.
2014, 34(5): 547-549.   doi: 10.11728/cjss2014.05.547
Abstract(2482) [PDF 1081KB](30)
Abstract:
Quantum Science Satellite is one of the first five space science missions, slated for launch in the framework of Chinese Academy of Sciences (CAS) Strategic Priority Research Program on space science. The project aims to establish a space platform with long-distance satellite and ground quantum channel, and carry out a series of tests about fundamental quantum principles and protocols in space-based large scale. The satellite will be launched at Jiuquan and on orbit for 2 years. The orbit will be circular and Sun-synchronous with an altitude of 600km. It crosses the descending node at 00:00LT. The satellite is under early prototype development currently.
2018, 38(2): 169-177.   doi: 10.11728/cjss2018.02.169
Abstract(776) [PDF 1110KB](1)
Abstract:
Intense magnetic fluctuations are recorded in the magnetosphere near the magnetopause when Flux Transfer Events (FTE) are passed by the THEMIS satellites. The power spectra of these fluctuations obtained by Fast Fourier Transform (FFT) show that the Power Spectra Density (PSD) peaks around the disturbance frequency of FTE (about 0.1Hz), and decreases from the proton gyrofrequency (about 1Hz) to 64Hz following a power law of P0f-α. These fluctuations are interpreted as magnetic turbulences in the kinetic regime in the Low Latitude Boundary Layer (LLBL). The results show that both the PSD and the slopes of the power spectra α decrease when the observing satellite position is more and more away from the magnetopause or the FTE location in the LLBL. However, α and the PSD are independent from the azimuthal position of FTE or local time of the low latitude magnetopause. All these observations suggest that the moving FTEs are the source for these magnetic fluctuations. Large scale perturbations on the magnetopause, e.g. FTEs and the associated magnetic turbulences, provide a hint which may reveal the interaction between the magnetosheath and the magnetosphere in a kinetic scale. Whether the magnetic turbulences can provide enough viscosity for the forming of the flow vortices on the magnetospheric side of FTEs or not need to be further confirmed.
2013, 33(6): 683-689.   doi: 10.11728/cjss2013.06.683
Abstract(941) [PDF 577KB](5)
Abstract:
For free-floating flexible-joint space robot system with uncertain parameters, the dynamics modeling, motion controller design and flexible vibration active suppression are developed. Dynamic equations of the system are established by the system's linear and angular momentum conservation and Lagrange equation. In order to overcome the limitations of that the traditional singular perturbation method only applies to the system with weak joint flexibility, a joint flexibility compensator is designed to improve the flexible-joint's stiffness of space robot system equivalently. On the above basis, the system is decomposed into a slow subsystem and a fast subsystem by singular perturbation method, and the controllers of the subsystems are designed. The slow subsystem's fuzzy robust sliding mode controller can compensate the uncertain parameters, decrease the rotation angle transmission errors caused by the flexible-joint, and realize the asymptotic tracking of the system desired trajectory. The fast subsystem controller can suppress the flexible vibration caused by flexible-joint actively. The simulation experimental results prove the efficiency of the hybrid controller.
2013, 33(6): 672-677.   doi: 10.11728/cjss2013.06.672
Abstract(1182) [PDF 1294KB](7)
Abstract:
The APXS (Alpha Particle X-ray Spectrometer) is installed on the outside of the Lunar Rover, so that the lunar rocks and soil can be studied by the mobility of the Rover and flexibility of the robotic arm. Because of being exposed outside the rover, APXS will have great impact by the complex outer heat flux. In view of this, a reasonable thermal design is necessary for APXS to ensure that the APXS detector and electronic devices operate within the temperature range of its allowance. In this paper, the thermal control designs of APXS and the thermal simulation calculation results based on its thermal control designs are summarized. And the calculation results have been validated by corresponding thermal balance tests.
2018, 38(3): 332-341.   doi: 10.11728/cjss2018.03.332
Abstract(1616) [PDF 4081KB](4)
Abstract:
Fast Magnetosonic (MS) waves are right-hand polarized waves. They propagate both inside and outside the plasmasphere, and the wave vectors are almost perpendicular to the ambient magnetic field. Fast MS waves can lead to local electron acceleration, scattering of outer radiation belt energetic electrons, and scattering of energetic protons etc. Using the fully and high-density approximated dispersion relations, the dispersion curve of fast MS with different wave normal angle is analyzed, and the minimum resonant energy between MS waves and ions (H+, He+, and O+) are calculated. The results show that, as the wave normal angle is relatively small, the minimum resonant energy obtained by the high-density approximated and fully dispersion relation is quite close to each other in a high density and weak magnetic field space plasma. Remarkable error occurs when the high-density approximated dispersion relation is used in the low and medium density space plasma or when the wave normal angle is greater than 88°. Therefore, the fully dispersion relation must be used in these cases.
2018, 38(4): 560-566.   doi: 10.11728/cjss2018.04.560
Abstract(690) [PDF 833KB](2)
Abstract:
The structures and dimensional parameters of space tether significantly affect their survivability against space debris collisions in complex space environment. This work addresses the probability analysis for double tethers and tape tethers severed by debris based on tether-debris collision model and Poisson distribution. The influence of debris on the survivability of space tethers is also studied. A double tether is a pair of parallel strings connected at a certain distance, and tape tethers can be treated as a specific type of single tethers with rectangular cross-sections. The probability of single tethers severed by space debris is modeled, and the survivability functions for double tethers and tape tethers are also formulated. Moreover, the survivability of tethers with different structures and dimensional parameters is calculated based on a cumulative debris flux model. The results show that double tethers and tape tethers are of higher survivability compared with single tethers.
2015, 35(3): 306-314.   doi: 10.11728/cjss2015.03.306
Abstract(923) [PDF 14054KB](0)
Abstract:
The model of ionospheric delay correction is established by only GPS and by fusing BDS, GPS and GLONASS with observations of pseudo distance smoothed by carrier phase and spherical harmonics. And some experiments of the global ionospheric inversion have been done. The variations process of ionospheric is fused daily in January, 2014 to obtain monthly comprehensive differential code bias product and did some analysis on the accuracy of the products. The fusion of the three systems not only increases the number of satellites observation but also improves the geometric distribution of the puncture point. The analysis result shows that the accuracy of inversion of global ionospheric of three system fusions is better than GPS system alone, about 5 to 10 increase in TECU. The Precision of monthly comprehensive differential code bias product of GPS is better than GLONASS, while the BDS stability is poor.
2013, 33(5): 569-576.   doi: 10.11728/cjss2013.05.569
Abstract(1771) [PDF 741KB](1)
Abstract:
This paper discusses the trajectory tracking and vibration suppression of free-floating flexible space manipulator with uncertain system parameters. The conception of virtual control force is used to design a virtual desired trajectory which reflects both flexible vibration and rigid motion. Then, in order to steadily track the trajectories of the base's attitude and the joint angle, the adaptive non-singular terminal sliding mode controller is proposed to track the desired trajectory. The controller integrates the advantages of terminal sliding mode technique, Fuzzy Wavelet Neural Network (FWNN) with good function approximation characteristic and robust control technology to process approximate error. In addition, adaptive algorithm is adopted for fuzzy wavelet neural network to adaptively adjust its all network weights and parameters, so the controller has strong robustness. Simulation results are given to illustrate the effectiveness of the proposed control scheme.
2014, 34(4): 489-496.   doi: 10.11728/cjss2014.04.489
Abstract(992) [PDF 1495KB](5)
Abstract:
This paper presents the dynamic characteristics of repeated fold-unfold and lock-unlock solar array, which is in a topological tree configuration. According to the first modal stiffness analysis, assumptions about solar array multi-body system are proposed. Deduced from Jourdain variation principle, dynamic model of solar array flexible multi-body system is built. Furthermore, the forward-inverse mixed dynamic model is established through forward recursive formulation and motion law of solar array hinges. In order to study the impact of flexible structures on solar array deployment, the motion parameters of solar array panels, such as rotation angle, angular velocity and angular acceleration, are obtained from numerical simulation, which is based on the structure and physical parameters of repeated fold-unfold and lock-unlock solar array prototype. The results can well predict dynamic behaviors of solar array during its deploying process. In conclusion, this study has laid a foundation for subsequent engineering applications of repeated fold-unfold and lock-unlock solar array.
2014, 34(3): 367-376.   doi: 10.11728/cjss2014.03.367
Abstract(878) [PDF 685KB](1)
Abstract:
The impact dynamics of space manipulator system capturing a satellite, and control of post-impact unstable system were discussed. The dynamics model of space manipulator system was derived by the second Lagrange equation. At the impact moment when the space manipulator capturing a satellite, the impact effect for the space manipulator was calculated by momentum impulse method. For stabilizing the post-impact unstable space manipulator and satellite combination system, the linear feedback and linear quadratic optimal composite control algorithm was proposed for the space manipulator stabilization control and flexible link vibration suppression, and there was no need for the position control of the free-floating base under the proposed control algorithm employed, which would save the fuel consumption of free-floating base thruster. Finally, numerical examples are proposed to simulate the impact effect for space manipulator motion state which is caused by the impact, and the effectiveness of above control algorithm is verified.
2015, 35(2): 230-236.   doi: 10.11728/cjss2015.02.230
Abstract(872) [PDF 1692KB](2)
Abstract:
Optimization design of the path of the space manipulator tip is an economic and efficiency way to reduce the attitude disturbance on the basement arising from the motion of manipulator. However, research on the motion trajectory optimization for space robot under the condition of multi-position restraint in the Cartesian space is rare. In this paper, the motion trajectory was parameterized on the basis of revised cubic spline. Disturbance on the basement arising from the motion of manipulator was expressed by the objective function about the interpolating point of the spline and the migration time between two adjacent restrained positions. The global optimization of the objective function was realized using genetic algorithm. Simulation results indicated that the presented approach can effectively reduce the influence of disturbance on the attitude of basement, which was caused by the motion of manipulator. The designed trace in joint space is twice continuously differentiable.
2000, 20(2): 185-191.   doi: 10.11728/cjss2000.02.185
Abstract(2075) [PDF 382KB](5)
Abstract:
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.
2016, 36(1): 92-98.   doi: 10.11728/cjss2016.01.092
Abstract(986) [PDF 1797KB](0)
Abstract:
The traditional folding solar array with large size and big mass, using single deployment and locking mechanism, can cause flutter during the spacecraft attitude adjustment or orbital transfer, and hence a fan-shaped solar array with repeated fold-unfold and lock-unlock mechanism scheme was designed. A virtual prototype model is established based on ProE/Adams co-simulation, and the motion parameter changing rule of the pivot panel at different motor rotational speeds is obtained. The deployment function verification test is carried out using the prototype. By comparing the simulation result with the test data, it can be known that the mechanism can be fully deployed and locked in time when the motor speed is changed in prescriptive range, and can be deployed and locked repeatedly. The simulation result is highly consistent with the test data, which shows that the design can meet the requirements.
2016, 36(2): 237-244.   doi: 10.11728/cjss2016.02.237
Abstract(715) [PDF 918KB](5)
Abstract:
This paper discusses the trajectory tracking and vibration suppression of free-floating flexible space robot with uncertain system parameters, which combines the advantages of time delay estimation control and robust H control. Time-delayed estimation is used to achieve unknown dynamics of space robot system online and to perform a compensation during the tracking control. L2 gain control is employed to achieve L2 interference suppression of time-delay estimation error, which could further improve the robustness of the system. At the same time, theoretical analysis proves that the introduction of L2 gain control can suppress the influence of time delay estimation error on the system to satisfy the robust H performance, and ensures all signals in the closed-loop system to be bounded. In addition, the virtual control force is proposed to transform the original control scheme, which can achieve both tracking the desired trajectory and suppressing the flexible vibration control target through only one control input. Simulation results and comparison chart are given to illustrate the effectiveness of the proposed control scheme and the active vibration suppression of flexible.
2018, 38(2): 147-168.   doi: 10.11728/cjss2018.02.147
Abstract(843) [PDF 3653KB](7)
Abstract:
In this paper the structures with scale of ion inertial length (di) in flux ropes at the magnetopause are studied based on MMS measurements. The results show that currents ( j m) of di scale are found to exist in many flux ropes with different scales, which flow in the -M direction in magnetopause local coordinates (i.e., in the same direction of the Chapman-Ferraro current at the magnetopause) and are carried by electrons' motion in the +M direction ( v em). Within the current structures, magnetosheath and magnetospheric plasma populations are mixed; the magnetic field has open topology; ions are non-magnetized, while electrons are frozen-in with the magnetic field lines; the N-component of electric field ( E n), which is Hall electric field in nature, substantially enhances (up to about 20mV·m-1), accompanying with notable fluctuations. Detailed analysis shows that the current, separation of electrons' motion from ions and the Hall electric field are closely related to each other, and obey the general Ohm's Law. In addition, we have also analyzed the MMS measurements of magnetic reconnection events at the magnetopause. It is found that structures similar to those in flux ropes are also present inside the reconnection region in many cases. Their scales are of di length. The directions (magnitudes) of the Hall electric field E N, current filament j M and electron velocity v eM are as same as (close to) those in flux ropes. On the bases of above observations and making use of the classical flux rope models, how the di-scale structures in flux ropes are formed is studied. It is suggested that they are likely to originate from the corresponding structures in the reconnection region at the magnetopause which play an essential role in the formation process of di-scale flux ropes.
2018, 38(3): 409-417.   doi: 10.11728/cjss2018.03.409
Abstract(1019) [PDF 3773KB](2)
Abstract:
Phase Change Material (PCM) is widely used in energy storage due to its huge latent heat. To overcome its drawback of poor thermal conductivity, a Phase Change Heat Exchangers (PCHE) which combine the advantage of heat exchanger and PCM is designed. It can be used cooling high density of heat flow rate surface in aero-space. Based on the phase change computing methods-Enthalpy method for solidification and melting model, the numerical simulation of a kind of plate PCHE, which used water and paraffin as cooling medium and phase-change material, is studied. The transient temperature distribution, solid-liquid phase interface changes and melting time are obtained under different gravity conditions. The results show the performances of PCHE satisfy the design request. comparing the results under different gravity conditions, Heat Transfer Enhancement Method (HTEM) is used by add fins and metal or ceramic foams to improve the efficiency of the PCHE under microgravity. It is valuable to the design and experiment research of space PCHE.
2010, 30(6): 601-606.   doi: 10.11728/cjss2010.06.601
Abstract(2435) [PDF 595KB](5)
Abstract:
High precision accelerometers are not only used to measure the non-gravitational forces such as thermal radiation pressure, solar radiation pressure and atmospheric drag, but also used to improve the microgravity level of the spacecraft as an inertial reference, namely to achieve the spacecraft's drag-free control. The basic operation principle of inertial sensor or accelerometer is introduced. The principles of several high-precision accelerometers are described, such as MEMS accelerometers based on the capacitive sensor, MEMS tunneling accelerometers, the superconducting accelerometer, the electrostatic accelerometer and inertial sensors with optical position detection and feedback control. The developmental trend and applications in the fields of the geoscience and fundamental physics of high-precision space-borne accelerometers are discussed. The main development trend is: high-precision and miniaturization MEMS accelerometers, weak stiffness and high-precision satellite-borne accelerometers and cold atom inertial sensors.
2014, 34(5): 550-557.   doi: 10.11728/cjss2014.05.550
Abstract(2281) [PDF 5663KB](3)
Abstract:
The Dark Matter Particle Explorer (DAMPE) mission is one of the five scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Science (CAS) approved in 2011. The main scientific objective of DAMPE is to detect electrons and photons in the range of 5GeV-10TeV with unprecedented energy resolution (1.5% at 100GeV) in order to identify possible Dark Matter (DM) signatures. It will also measure the flux of nuclei up to above 500TeV with excellent energy resolution (40% at 800GeV), which will bring new insights to the origin and propagation high energy cosmic rays. With its excellent photon detection capability, the DAMPE mission is well placed for new discoveries in high energy-ray astronomy as well.
2014, 34(1): 109-115.   doi: 10.11728/cjss2014.01.109
Abstract(1296) [PDF 2116KB](4)
Abstract:
Aiming at the relative control problem of reference satellite maneuver-considered formation flying, a finite-time control method based on terminal sliding mode (TSM) is given. Based on the dynamic model of formation satellites relative motion, a finite-time terminal sliding controller is designed, and it is proven that the system state error can converge in finite time under the controller. Lastly, the formation reconfiguration and the formation keeping considering reference satellite maneuver are simulated and analyzed with the control method. The results show that the finite-time control method based on terminal sliding mode has higher formation control precision as well as faster error convergence speed compared with the traditional linear sliding mode.
2018, 38(1): 9-18.   doi: 10.11728/cjss2018.01.009
Abstract(940) [PDF 7542KB](2)
Abstract:
Coronal Mass Ejections (CME) are an important source of Solar Proton Events (SPE). Their speeds and source region locations have significant effects on SPE productions. In this paper, all halo CME in recent five years are statistically analyzed. The results show that fast halo CME with small angle distances are more likely to produce SPE, especially those halo CME with the speed greater than 1200km…-1 and the angle distance less than 60°. Three fast halo CME without SPE are elaborately studied. The results show that CME's main body moving direction and the variations of interplanetary magnetic fields also have important impacts on SPE emerging. Consequently, in daily operational space environment forecasts, an accurate SPE forecast must take various factors into account, such as CME burst speed, source region location, CME main body ejection direction, interplanetary environment, and so on.
2017, 37(4): 499-506.   doi: 10.11728/cjss2017.04.499
Abstract(694) [PDF 859KB](5)
Abstract:
The trajectory tracking control problem of space robot system with uncontrolled base is discussed. Considering the existence of uncertain parameter and unknown dead-zone in the space robot, an L2 back-stepping control scheme based on the disturbance observer is proposed. Firstly, the dynamic model of system in inertia space is established by the combination of the second Lagrange method and Jacobi matrix. Then, the disturbance observer is used to observe and compensate the model error, and the observer error is eliminated by the method of L2 disturbance suppression. Meanwhile, a fuzzy compensator is used to compensate the bad effect caused by dead-zone. The control scheme doesn't need to know the accurate inertia parameters and linearly parameterize the dynamic model. Moreover, it is not necessary to estimate the upper bound of system uncertainties and the dead-zone parameters, which simplifies the system control. A planar space robot with two links is simulated to verify the feasibility of the control scheme.
2018, 38(1): 19-28.   doi: 10.11728/cjss2018.01.019
Abstract(813) [PDF 2367KB](2)
Abstract:
Flux Transfer Events (FTE) are related to magnetic reconnection. The typical characteristic of FTE is bipolar variation of the field component normal to the local magnetopause. There still exist different views about FTE global topology on the magnetopause. In different models, the FTE structures are either reconnected flux tubes, or magnetic flux ropes formed by multiple X-line reconnection or sheared magnetic loops formed by single X-line reconnection. To infer the global configuration of FTE, a statistical study of axial orientations of 505 FTE observed by Cluster during one dayside magnetopause crossing season is performed. The result shows that most FTE have north-south-orientated axes roughly aligned with the local magnetospheric flux tubes at both the low-and middle-latitude flanks. However, most FTE have dawn-dusk-orientated axes which are more consistent with the single or multiple X-line orientations at high latitude, especially near the cusp. These statistical features will improve our understanding about the global topology of FTE.
2017, 37(6): 659-666.   doi: 10.11728/cjss2017.06.659
Abstract(748) [PDF 1265KB](5)
Abstract:
A deep understanding of the relationship between geomagnetic SC (Sudden Commencement) and DPP (Dynamic Pressure Pulse) is important for comprehensively understanding the response characteristics of geomagnetic field to interplanetary disturbance and improving the ability of SC prediction. In this paper, 363 SC events observed between 1994 and 2011 are the objectives. Firstly, whether there are corresponding DPP events associated with the SC events or not are determined by using automatic DPP recognition algorithm. Secondly, the characteristics of the DPP events and the SC events as well as their relationship statistically are analyzed. The results are as follows. 91% of the SC events are associated with the DPP events, and 53% of the SC events are associated with the shocks. The DPP events and the shocks are observed by WIND satellite. This result indicates that DPP is the main cause of SC. Most of the DPP events (70%) that cause the SC events are associated with large scale solar wind structures, such as Interplanetary Coronal Mass Ejections (ICME), Corotating Interaction Region (CIR) and complex projections aused by ICME and/or CIR. And the averaged dynamic pressure amplitude change of the DPP events is 3.9nPa. Strong DPP events account for 42% of all the events. There is an obvious relationship between the amplitude of the SC events and the absolute dynamic pressure change as well as the difference of the square root of the dynamic pressure of the DPP events, and the correlation coefficients are 0.79 and 0.82, respectively. The correlations between them are much stronger when the interplanetary magnetic field is southward. Although the duration, speed and amplitude of DPP have a certain influence on the duration of SC respectively, there is no obvious relationship between them. These results contribute to the prediction of SC based on DPP parameters.
2018, 38(3): 368-372.   doi: 10.11728/cjss2018.03.368
Abstract(868) [PDF 2249KB](0)
Abstract:
Numerical simulations of condensation heat transfer in triangle microchannels are presented. The model is established on the Volume of Fluid (VOF) approach and the user-defined routines which includes heat transfer at the vapor-liquid interface and latent heat. The predictive accuracy of the numerical model is assessed by comparing the heat transfer coefficient with the available empirical correlations in the literature. The influence of gravity and surface tension on the liquid-vapor interface distribution and heat transfer performance are analyzed. No obvious effect of the gravity is observed in the liquid-vapor interface distribution and the average cross sectional heat transfer coefficient. Surface tension, which plays a dominate role during the condensation in non-circular microchannels, leading to reduction of the condensate film thickness at the sides of the channel and accumulation of the condensate at the corners of the channel, giving rise to smaller thermal resistance and better heat transfer performance.
2018, 38(3): 315-331.   doi: 10.11728/cjss2018.03.315
Abstract(697) [PDF 8631KB](3)
Abstract:
A moderately intense substorm from 10:40UT to 12:10UT on 13 March 2008 observed by THEMIS probes is examined to analyze the global evolution of the substorm in the magnetotail. During this substorm, five THEMIS probes are arranged along the x-axis in the vicinity of the midnight, from the radical distance of about 8.7 to 13.2Re. Magnetic field dipolarization and plasma sheet expansions are all observed by different probes after the substorm onset. The average velocity of the plasma sheet expansions is about 140km·s-1. Two types of dipolarization are detected in this substorm. One type is dipolarization front which is associated with the Bursty Bulk Flow (BBF). The other type is global dipolarization which is associated with plasma sheet expansions.The occurrence of Pi2 pulsation can be observed at low, medium and high latitudes 7 minutes later from the substrom onset. The amplitude of Pi2 pulsation gradually increases with the increase of latitude. The ion bulk velocity in the substorm event is mainly caused by the ion drift velocity, and the measured electric field is the induced electric field generated by the change of the local magnetic flux.
2018, 38(3): 307-314.   doi: 10.11728/cjss2018.03.307
Abstract(859) [PDF 4043KB](5)
Abstract:
The responses of the magnetopause in the distant magnetotail to the interplanetary and solar wind conditions, especially to the variation of the solar wind velocity, are studied by WIND and ARTEMIS data. It is found that the properties of sustaining dense high-speed flow were observed by P2 satellite in the magnetosphere on 13 September 2011, which suggests that the satellite passed through the magnetopause and entered the magnetosheath region. The data are analyzed using the minimum variable method. The results show that the normal of the magnetopause is along the direction of the solar wind velocity. According to the similar triangular theorem, it can be deduced that the deflection scale of the magnetopause is about 10Re and 6Re in y and z direction respectively. And the relative position of the P1 and P2 satellites also confirmed this opinion. The analyses suggest that the magnetopause location and shape in this event are mainly affected by the solar wind speed in the distant magnetotail. The result can provide observational evidence for establishing the magnetopause model which includes the effects of the solar wind vy and vz.
2018, 38(5): 585-590.   doi: 10.11728/cjss2018.05.585
Abstract(658) [PDF 3440KB](8)
Abstract:
The Strategic Priority Program on Space Science in 2011-2017 (hereafter referred to as SPP I), which officially went ahead in 2011, marks that a new chapter of Chinese space endeavor has been opened. The 4 satellites, Wukong/DAMPE, SJ-10, Mozi/QUESS and Insight/HXMT, has been achieving promising scientific results since their launch, e.g., Wukong directly detected a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons. To enable the sustainable development of China's space science endeavor, the Strategic Priority Program Ⅱ on Space Science (hereafter referred to as SPP Ⅱ) was officially approved in late 2017. SPP Ⅱ includes 4 satellites-EP, ASO-S, SMILE and GECAM, Intensive Study of Future Space Science Missions, Advanced Research of Space Science Missions and Payloads, Space Science Mission Concept Research, and Data Analysis Research. Dedicated to exploring the unknown, the program is aiming to address scientific questions such as the origin and evolution of the universe and life, search for extraterrestrial life, and the impact of the Sun and the solar system on Earth and human development. Chinese space science community is committed to contributing to the progress of human civilization.
2005, 25(2): 93-98.   doi: 10.11728/cjss2005.02.093
Abstract(2308) [PDF 1746KB](4)
Abstract:
2018, 38(4): 539-545.   doi: 10.11728/cjss2018.04.539
Abstract(588) [PDF 8371KB](3)
Abstract:
Hydroxyapatite (HAP) has excellent biocompatibility and bioactivity. Synthetic HAP can be widely used as medical and eco-friendly materials. In order to know valuable information of study and development of bone tissue engineering, the influence on HAP crystals growth by the changed of fluid field and the chosen of substrates are studied. The composites materials are used as substrates, which are made of Polydimethylsiloxane (PDMS)/HAP, PDMS/bioglass, and pure bioglass, respectively, and the effect of different substrates on HAP growth are analyzed. The results show that HAP crystals growth rates are different on different substrates when the flow rate is zero. HAP crystals growth rate is highest on PDMS/HAP substrate. However, it is lowest on pure bioglass substrate. Moreover, the influence of different flow rates of HAP growth solution (Simulated Body Fluid, SBF) by a homemade flow rate adjustment apparatus is studied. Three different flow rates, 10ml/min, 15ml/min, and 30ml/min, are used in this study. Under SBF flow conditions, the sizes of HAP crystals increased and the amount of amorphous precipitate decreased.
2018, 38(3): 418-426.   doi: 10.11728/cjss2018.03.418
Abstract(624) [PDF 4597KB](2)
Abstract:
In the traditional polar coordinate system, the latitude and longitude grids will undergo serious deformation in the polar regions. This deformation will cause the design matrix of point-mass model equation unsolvable, and the spherical harmonic method is singular near the two polar points. In this paper, the singularity problem in the calculation of disturbing gravity and the instability problem during the construction of point mass model in polar regions is studied. The singularity elimination algorithm is introduced in spherical harmonic method and the construction of point mass model based on pole transform is proposed. Numerical experiment results show that the singularity elimination algorithm can effectively solve the singularity problem near the poles, and the structure of point mass model based on the pole transform method is stable and the model can achieve the same accuracy compared with the traditional one, which provides a new way for disturbing gravity fast calculation of polar region aircraft.
2009, 29(5): 502-507.   doi: 10.11728/cjss2009.05.502
Abstract(2131) [PDF 515KB](2)
Abstract:
The new method of predicting the ionospheric F2 layer in the Asia Oceania region is based on cross-correlation theory of ionospheric parameters and the twelve-month running mean of sunsport number (R12). The R12 is substituted for the ionospheric prediction index Ic produced from f0F2 of Chongqing, and the B coefficients interpolated by three different R12 data are not used, which can reduce the error caused by converting R12 into Ic. Lots of data at several sounding stations have been prudently selected and suplemented based on the old predicting method, and the $B$ coefficients needn't be computed any more, which can avoid interpolation error resulting from the intermediate link. A comparison of several predicting results shows that the new edition is much more accurate.
2010, 30(5): 392-403.   doi: 10.11728/cjss2010.05.392
Abstract(3077) [PDF 2183KB](5)
Abstract:
Chang'E-1 is the first lunar mission in China, which was successfully launched on Oct. 24th, 2007. It was guided to crash on the Moon on March 1, 2009, at 52.36ºE, 1.50ºS, in the north of Mare Fecunditatis. The total mission lasted 495 days, exceeding the designed life-span about four months. 1.37 Terabytes raw data was received from Chang'E-1. It was then processed into 4 Terabytes science data at different levels. A series of science results have been achieved by analyzing and applicating these data, especially "global image of the Moon of China's first lunar exploration mission''. Four scientific goals of Chang'E-1 have been achieved. It provides abundant materials for the research of lunar sciences and cosmochemistry. Meanwhile these results will serve for China's future lunar missions.
2015, 35(6): 653-663.   doi: 10.11728/cjss2015.06.653
Abstract(1699) [PDF 2168KB](14)
Abstract:
A future Chinese mission is introduced to study the coupling between magnetosphere, ionosphere and thermosphere, i.e. the Magnetosphere-Ionosphere-Thermosphere Coupling Small Satellite Constellation (MIT). The scientific objective of the mission is to focus on the outflow ions from the ionosphere to the magnetosphere. The constellation is planning to be composed of four small satellites; each small satellite has its own orbit and crosses the polar region at nearly the same time but at different altitude. The payloads onboard include particle detectors, electromagnetic payloads, auroral imagers and neutral atom imagers. With these payloads, the mission will be able to investigate acceleration mechanism of the upflow ions at different altitudes. Currently the orbits have been determined and prototypes of some have also been completed. Competition for next phase selection is scheduled in late 2015.
2013, 33(1): 1-5.   doi: 10.11728/cjss2013.01.001
Abstract(2468) [PDF 662KB](2)
Abstract:
The Meridian Project is a ground-based network program to monitor solar-terrestrial space environment, which consists of a chain of 15 ground-based observatories located roughly along 120°E longitude and 30°N latitude. The Meridian project started in 2008, and its construction was completed by 2011. The integration and test phase of the Meridian Project conducted in 2011 demonstrated its observation capabilities as expected. The project will be in full operation in 2012. This report gives an overview of the recent development and preliminary results of the Meridian Project since 2010.
2015, 35(1): 116-125.   doi: 10.11728/cjss2015.01.116
Abstract(1348) [PDF 1577KB](5)
Abstract:
Satellite networks have many inherent advantages over terrestrial networks and have become an important part of the global network infrastructure. Routing aimed at satellite networks has become a hot and challenging research topic. Satellite networks, which are special kind of Delay Tolerant Networks (DTN), can also adopt the routing solutions of DTN. Among the many routing proposals, Contact Graph Routing (CGR) is an excellent candidate, since it is designed particularly for use in highly deterministic space networks. The applicability of CGR in satellite networks is evaluated by utilizing the space oriented DTN gateway model based on OPNET(Optimized Network Engineering Tool). Link failures are solved with neighbor discovery mechanism and route recomputation. Earth observation scenario is used in the simulations to investigate CGR’s performance. The results show that the CGR performances are better in terms of effectively utilizing satellite networks resources to calculate continuous route path and alternative route can be successfully calculated under link failures by utilizing fault tolerance scheme.
2009, 29(3): 262-267.   doi: 10.11728/cjss2009.03.262
Abstract(3497) [PDF 805KB](0)
Abstract:
Two particular types of Langmuir wave activities are found within the Magnetic Cloud Boundary Layers (MCBL): Langmuir wave enhancements in entire region of MCBL compared with the adjacent magnetic cloud body and sheath region for majority MCBL and the rapid Langmuir wave burst phenomena associated with broad-band Doppler shifted ion-coustic wave activities for a few MCBL. On 3 Oct., 2000, WIND detected a typical MCBL inside which rapid Langmuir waves burst was observed. The Langmuir waves burst was right corresponded to the magnetic field minimum within the MCBL. The analysis based on high resolution electron distribution function data indicates that the bump-on-tail instability, resulting from the electron beam with beam velocity vb about7×10^3 km/s, is responsible for the rapid Langmuir waves burst.
2014, 34(1): 29-37.   doi: 10.11728/cjss2014.01.029
Abstract(1134) [PDF 4882KB](2)
Abstract:
GPS TEC data are used to analyze ionospheric response to recurrent geomagnetic activity in 2008 and 2009. Periodic analysis indicates that the significant periodicities of 9 and 13.5 days exist in in global mean Total Electron Content (TEC), ap index and solar wind speed but not in solar F10.7 index. This shows that the short period variations in TEC are mainly related to recurrent geomagnetic activity caused by solar high-speed stream. The local time and latitudinal analysis indicates that the positive and negative perturbations always occur at high-latitude of northern and southern hemisphere at nighttime. At middle to low latitudes, there is mainly positive perturbation at night. The amplitude of the nighttime disturbance in high latitude is larger than middle to low latitudes at night. The daytime TEC response at middle to low latitude is generally in-phase with ap's perturbation. There is a time delay between TEC disturbance and ap variations at high-latitude of southern hemisphere. The amplitude of 9-day, 13.5-day periodicities in 2008 are larger than those in 2009.
2007, 27(3): 245-249.   doi: 10.11728/cjss2007.03.245
Abstract(2005) [PDF 2239KB](0)
Abstract:
Currently, TTC （Tracking, Telemetry and Command） for satellites of our country is mainly executed by Ground-Based TTC network. With the increment of requirement for different kinds of purposes, the numbers of satellites in lower orbits increase rapidly. It is very difficult to meet the requirements of the satellites only based on ground-based TTC network. To seek a new, effective and economical mode to TTC lower orbit satellites is absolutely necessary for our country and to apply space-based TTC technology is an appropriate way to solve ground-based equipment shortages. Based on analysis of Tracking and Data Relay Satellite System （TDRSS） of NASA （National Aeronautics and Space Administration of the United States）, a new mode, space-ground-based TTC Mode （SGBM） for lower orbit satellites, is proposed. In this paper, the operating principle of space-ground-based TTC mode is discussed, the simulation system used to simulate space-ground-based TTC mode is designed, and the key technologies need to be solved when using space-ground-based TTC mode is analyzed. The different functions of space-ground-based TTC mode are verified based on the developed simulation system. The simulation results show that the proposed satellite TTC mode is feasible and reliable, and the requirement of lower orbit satellite can be met by using the mode.
2016, 36(3): 245-266.   doi: 10.11728/cjss2016.03.245
Abstract(1023) [PDF 4166KB](11)
Abstract:
The Solar Polar ORbit Telescope (SPORT) project for space weather mission has been under intensive scientific and engineering background studies since it was incorporated into the Chinese Space Science Strategic Pioneer Project in 2011.SPORT is designed to carry a suite of remote-sensing and in-situ instruments to observe Coronal Mass Ejections (CMEs),energetic particles,solar high-latitude magnetism,and the fast solar wind from a polar orbit around the Sun. The first extended view of the polar regions of the Sun and the ecliptic enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere,and the solar high-latitude magnetism giving rise to eruptions and the fast solar wind.Coordinated observations between SPORT and other spaceborne/ground-based facilities within the International Living With a Star (ILWS) framework can significantly enhance scientific output.SPORT is now competing for official selection and implementation during China's 13th Five-Year Plan period of 2016-2020.
2018, 38(3): 373-379.   doi: 10.11728/cjss2018.03.373
Abstract(665) [PDF 4436KB](8)
Abstract:
In order to understand the transition process of thermocapillary convection of low Prandtl number (Pr) fluids, a series of three-dimensional numerical simulations on thermocapillary convection of Pr=0.011 fluid in a shallow annular pool are performed. Results indicate that the flow is axisymmetric steady flow at a small Marangoni number. When Marangoni number exceeds a critical value, the flow destabilizes and bifurcates to the hydrothermal wave. In this case, the wave number decreases and the fundamental frequency increases with the increase of Marangoni number. When Marangoni number continue increasing, the hydrothermal waves are enhanced and bifurcated to the radial waves. During this transition, there exists a sharp drop of the wave number. Finally, the noise on frequency spectrum increases and behaves in multi-frequencies. Therefore, the bifurcation route of thermocapillary convection is from axisymmetric steady flow, hydrothermal wave, radial waves with one frequency to three-dimensional oscillatory flow with multi-frequencies.
2014, 34(5): 703-709.   doi: 10.11728/cjss2014.05.703
Abstract(1081) [PDF 9491KB](4)
Abstract:
FY-3 is the second generation polar-orbiting meteorological satellite of China. The first satellite named FY-3A of this series was launched on 27 May 2008. The first operational satellite named FY-3C of this series was launched on 23 September, 2013. The new generation satellites are to provide three-dimensional, quantitative, multi-spectral global remote sensing data under all weather conditions, which will greatly help the operational numerical weather prediction, global climate change research, climate diagnostics and prediction, and natural disaster monitoring. They will also provide help for many other fields such as agriculture, forestry, oceanography and hydrology. With the abovementioned capability, the FY-3 satellites can make valuable contributions to improving weather forecasts, global natural-disaster and environmental monitoring.
2015, 35(4): 461-472.   doi: 10.11728/cjss2015.04.461
Abstract(1205) [PDF 1655KB](0)
Abstract:
Based on a large database of satellite anomalies containing 2384 anomalies from NGDC (USA) and 263 malfunctions from 19 satellites of China (CHN), and with a large set of hourly space weather condition parameters data over the period of 1963-2012, this paper quantifies statistically space weather conditions which may induce different spacecraft anomalies including Single Event Upset (SEU), Electrostatic Discharge (ESD) induced by surface charging, and Electron Caused Electromagnetic Pulse (ECEMP) resulting from internal, deep dielectric charging. The results are as follows. (1) Most anomalies of SEU, ECEMP occurred on quiet space conditions, whereas geomagnetic storms tended to happen during the 3 days (72h) before or after satellite anomalies started, and the most probable time for anomalies was on the third day (48～72h) after the minimum Dst (Dstmin). (2) Geomagnetic activities and high-energy electrons showed apparent effects on anomalies of ESD. Occurrence probabilities of ESD and ECEMP clearly increased in equinoxes (March, September), and such seasonal characteristic was consistent with that in occurrence probabilities of magnetic storms and Relativistic Electrons Flux Enhancement Events (REFEE). For 93.6% anomalies of ESD, geomagnetic storms tended to happen during 72h before, after ESD started, and the most probable occurring time was 0～48h before Dstmin or 0～24h after Dstmin. 54.9% anomalies occurred on geomagnetic conditions of Dst <-30nT, and intensities of storms seemingly influenced ESD little. 40.6% anomalies occurred at the time when the hourly >2MeV electron flux is above 10^3pfu (1pfu =1cm-2·s-1·sr-1). For 81.9% anomalies of ESD, the hourly maximum of high-energy electron flux, during 72h before or after ESD started, was above 10^3pfu, and the most probable time interval was 48～72h before electron flux maximum, when 33.3% anomalies occurred. (3) High-energy electrons showed apparent effects on SEU of GEO from CHN database, 42.5% of anomalies occurring on conditions of electron flux ≥ 103pfu. For those anomalies, the hourly maximum of > 2MeV electron flux exceeded 103pfu during 72h before or after which started. The anomaly occurrence probabilities at the time of 48～72h before and 48～72h after electron flux maximum, were comparative, being about 23.0%. (4) Solar Proton Event (SPE) showed more influence on SEU of GEO. SPEs seemed no regular seasonal variations based on data during 1975-2013, while occurrence probabilities of SEUs showed little seasonal dependence. For 22.0% SEUs of GEO from CHN database, SPEs occurred during 72h before or after anomalies started, and SEUs might occur at any time of the 72h before or after the maximum of >10MeV proton flux.
2016, 36(6): 925-931.   doi: 10.11728/cjss2016.06.925
Abstract(837) [PDF 1360KB](1)
Abstract:
Solar imaging spectrometer in the extreme ultraviolet band is an important kind of instrument for solar observation. But traditional solar imaging spectrometer cannot observe the Sun in a large field of view simultaneously. Slitless imaging spectrometer allows imaging spectroscopy with high spatial and temporal resolution. Slitless imaging technique is a revolutionary technique for solar research in the extreme ultraviolet band. In this paper, a reconstruction algorithm is studied which has been used in a slitless imaging spectrometer, but it is found that there is a systematic error in the reconstruction result. A new optical design is proposed to solve this problem. By reconstructing the simulated data, the effectiveness of this design is proved. The reconstruction of new design shows better measurement accuracy in Doppler velocity. It will provide more accurate data for space weather studies.
2014, 34(5): 605-647.   doi: 10.11728/cjss2014.05.605
Abstract(1251) [PDF 458KB](0)
Abstract:
In the past two years, many progresses have been made in magnetospheric physics by using the data of Double Star Program, Cluster, THEMIS and RBSP missions, or by computer simulations. This paper briefly reviews these works based on papers selected from the 126 publications from March 2012 to March 2014. The subjects cover various sub-branches of magnetospheric physics, including geomagnetic storm, magnetospheric substorm and magnetic reconnection.
2004, 24(5): 354-359.   doi: 10.11728/cjss2004.05.354
Abstract(1869) [PDF 466KB](2)
Abstract:
2007, 27(5): 420-424.   doi: 10.11728/cjss2007.05.420
Abstract(2076) [PDF 1675KB](1)
Abstract:
A new method was developed to estimate the radar system phase bias and calibrate the radar system. Using the data collected by this radar, the phase differences of the meteor echo between each receiver pairs are estimated, by taking account of the receiver pairs geometries the linear equation matrix is formed, the phase bias between each receiver pairs in the least-squares sense is solved, and finally the location of meteor echoes after calibration is found. Compared with the conventional method, this method can use the history data to find the system phase bias, without the need for additional hardware. It can routinely use for off-line to correct data collected using the bias estimated before. The data of Wuhan Meteor Radar （WHMR） between April 2004 to June 2004 is used as an example, the bias of the radar system is estimated and the data is used after calibration to calculate the location of the meteor echoes. The data calibrated using this method show a more consistent height distribution in terms of number of echoes with the same meridian.
2013, 33(1): 108-114.   doi: 10.11728/cjss2013.01.108
Abstract(1905) [PDF 598KB](5)
Abstract:
Two-stage helical repeated fold-unfold and lock-unlock solar wing is designed. Its function analysis is conducted. Firstly, its working principle is analyzed. Based on the requirement of two-stage helical repeated fold-unfold and lock-unlock solar wing, technological parameters and specific structural parameters are determined. The fold-unfold and lock-unlock solar wing unfolding characteristic is analyzed. According to the transitive relation analysis of repeated fold-unfold and lock-unlock solar wing, the analysis modeling on its deploying kinetic characteristics, including forward kinematics and inverse kinematics, are derived. Simulation results show that plane degree and synchronization degree of the solar wing can meet the requirements of specifications, which lays the theoretical foundation to further research the fold-unfold and lock-unlock solar wing in the future.
2005, 25(1): 76-80.   doi: 10.11728/cjss2005.01.076
Abstract(1689) [PDF 1685KB](3)
Abstract:
2015, 35(4): 438-444.   doi: 10.11728/cjss2015.04.438
Abstract(900) [PDF 3703KB](7)
Abstract:
The D and E regions lie in the lower ionosphere region of 60～110km height. This region is influenced by solar radiation, cosmic noise radiation, atmospheric electrodynamics and many factors, and there exists a variety of incredible variation characteristics. Even in the magnetically quiet day, atmospheric electrodynamics can make a significant effect on this region except solar radiation. In the D region, there exists radio waves strong absorption, which can influence the transmission of high frequency radio waves. Electron and ion density can be obtained from the Incoherent Scatter Radar (ISR) Arecibo, located at Puerto Rico. ISR data can be used to study the movement characteristics of the lower ionosphere in mid-latitude, and get the electron density curves changing with time and height, which present obvious diurnal changing phenomenon. The spectrum of the data is analyzed to probe diurnal effects of electron density changes. Besides the electron density height profiles have been drawn, and observe obvious plasma descending from the base of F-layer to E region. The layer structure characteristics of the lower ionosphere and electron density changing show that there exists different degree of disturbance. By analyzing the influencing factors it is concluded that the atmospheric tides and the acoustic gravity waves can cause disturbance to lower ionosphere, which is coupled with the atmosphere in certain degree.
2008, 28(1): 6-11.   doi: 10.11728/cjss2008.01.006
Abstract(2093) [PDF 3060KB](1)
Abstract:
With electro-magnetic simulating equipment established on the ground Cu-Pb binary immiscible alloy are produced successfully,and microstructure and friction performance of the alloy samples are analyzed and tested.The analyzed results of microstructure show the alloy specimens produced on electro-magnetic simulating microgravity condition overcome severe phase separation due to gravity,the minority phase of simulating samples are well distributed in matrix,the lower contents of the minority phase is,the smaller size of dispersive phase is and the better it are distributed;test results of friction performance show friction performance of simulating samples is evidently better than the matrix metal,friction factor become small and wear properties rapidly reduce first and slowly increase later with increase of the minority phase contents.Simultaneously the test results are analyzed and discussed briefly.
2011, 31(2): 260-268.   doi: 10.11728/cjss2011.02.260
Abstract(2358) [PDF 717KB](0)
Abstract:
A kind of nonlinear dynamics model of free-floating dual-arm space robot system is based on Lagrange method, and the dynamics model of object is presented based on Newton-Euler method. Based on the results and closed kinematic chain constraints, the dynamics model of synthetical system is obtained, and the control problems for object to track the desired trajectory in workspace and adjustment of interactive forces due to the interaction between the object and the end-effectors are discussed. Because of the high complexity of structure and the uncertainty of parameter of such systems, the scheme of variable structure global sliding-mode control with better robustness to uncertainty and disturbance is proposed to track the desired trajectory of object, and the corresponded scheme of internal forces control is proposed synchronously. Therefore, the object position and internal forces can be regulated simultaneously. A fuzzy controller is designed to reduce shiver due to the inherent defect of sliding-mode control and ensure rapid response. The fuzzy controller can tune the sliding-mode control law parameters automatically according to the relationship between the system state and switch surface. The effect of the controllers is testified by computer simulation.
2019, 39(2): 250-266.   doi: 10.11728/cjss2019.02.250
Abstract(1116) [PDF 894KB](5)
Abstract:
2014, 34(1): 11-23.   doi: 10.11728/cjss2014.01.011
Abstract(989) [PDF 854KB](2)
Abstract:
Predicting whether an Interplanetary (IP) shock driven by solar eruptions will encounter the Earth is the prerequisite and foundation to predict its arrival time at the Earth and the geoeffectiveness. Using 542 IP shock events associated with solar eruptions during 1997—2006, the influence of intensity, location, initial shock speed, duration of solar eruptions and Solar Energetic Particles (SEP) flux upon the propagation of IP shocks is investigated statistically, and then key physical parameters mentioned above that obviously influence the IP shock's arrival at the Earth are chosen. Finally, an Earth-directed and Earth-away Shock Prediction Model (EdEaSPM) based on not only solar parameters but also SEP parameters is built. The results of historical prediction show that the success rate of EdEaSPM model is about 66%, which is significantly higher than that of the other prevailing models, STOA, ISPM and HAFv2. The False Alarm Ratio (FAR) of EdEaSPM is less than 50% and the situation that FAR is too high is improved. For the ratio of number of events with shock forecast to that with shock detection, bias, although the value of Bias of all of the models is greater than 1, the Bias of EdEaSPM is the smallest and most close to 1. For the other forecast skill scores, TSS, HSS and GSS, the EdEaSPM performs better than HAFv2 model. In addition, prediction test of 6 IP shock events between Jan. and Oct. 2012 shows that the forecast results are consistent with observations. The EdEaSPM model can forecast whether an IP shock will encounter the Earth about 1 to 3 days in advance, and its accuracy is comparable to that of the other prevailing models. In particular, the success rate and false alarm ratio are improved significantly.
2014, 34(5): 525-534.   doi: 10.11728/cjss2014.05.525
Abstract(1433) [PDF 7409KB](9)
Abstract:
Chang'E-1, the first lunar mission in China, was successfully launched on October 24, 2007, which opened the prelude of China's Lunar Exploration Program. Later on, the Chang'E-2 and Chang'E-3 satellites were successfully launched in 2010 and 2013, respectively. In order to achieve the science objectives, various payloads boarded the spacecraft. The scientific data from these instruments were received by Beijing and Kunming ground stations simultaneously. Up to now, about 5.628 Terabytes of raw data were received totally. A series of research results has been achieved. This paper presents a brief introduction to the main scientific results and latest progress from Chang'E-3 mission.
2018, 38(4): 460-468.   doi: 10.11728/cjss2018.04.460
Abstract(740) [PDF 3465KB](1)
Abstract:
This study uses ECMWF fifth-generation reanalysis, ERA5, which extends to the mesopause, to construct the Initial Conditions (IC) for WACCM (Whole Atmosphere Community Climate Model) simulations. Because the biases between ERA5 and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature data are within ±5 K below the lower mesosphere, ERA5 reanalysis is used to construct IC in the lower atmosphere. Four experiments are performed to simulate a Stratospheric Sudden Warming (SSW) event from 5 to 15 February 2016. The simulation using the WACCM default climatic IC cannot represent the sharp meteorological variation during SSW. In contrast, the 0~4 d forecast results driven by ERA5-constructed IC is consistent with ERA5 reanalysis below the middle mesosphere. Comparing with WACCM climatology ICs scheme, the ICs constructing method based on ERA5 reanalysis can obtain 67%, 40%, 22%, 4% and 6% reduction of temperature forecast RMSE at 10 hPa, 1 hPa, 0.1 hPa, 0.01 hPa and 0.001 hPa respectively. However, such improvement is not shown in the lower thermosphere.
2011, 31(5): 659-665.   doi: 10.11728/cjss2011.05.659
Abstract(2255) [PDF 485KB](0)
Abstract:
Connected-Element Interferometry (CEI) was a passive angular tracking method with the merits of high phase precision, flexible network distribution and nearly real-time processing due to short length of baselines. Firstly, feasibility of ambiguity solution in CEI-based orbit determination for GEO was analyzed. Integer ambiguity must be primarily solved in the orbit determination for TDRS because of its low initial orbit precision. It could be calculated by the high precise range measurement if the master control station could obtain range measurement, while the method of parameter estimation by fixing integer ambiguity was used without high precise range measurement. The simulation results indicated that this method was effective when the systematic error was less than 1.0m. The orbit determination precision for the satellite belt between 80°E and 140°E was gained, when the systematic error was 0.1m, along-track positional error component of the 110°E satellite reached 25 m, while 82m and 34m respectively for the 80°E satellite and 140°E satellite.
2014, 34(1): 53-62.   doi: 10.11728/cjss2014.01.053
Abstract(1109) [PDF 5275KB](1)
Abstract:
Using the continuous observation data of Hainan VHF radar (19.5°N, 109.1°E; dip latitude 8.1°N) on July 15—22, 2011, the characteristics of 3m scale Field-Aligned ionospheric Irregularities (FAI) in Eastern Asia low latitude are analyzed. The main results show the E region FAI echoes almost occur everyday during the whole observation period. They can occur both in day and night and have different complicated structures. According to their occurrence time and structure, the E region FAI echoes can be classified into the following three cases. First is the lower continuous echoes, which mainly occur from the later afternoon to pre-midnight (17:30LT—23:00LT) with evident enhanced echo intensity and negative (downward/southward) Doppler velocities. The second is the upper descend layer structures, which mainly appear from nearly midnight to pre-sunrise (23:00LT°05:00LT) with more enhanced echo intensity and both positive and negative Doppler velocities, where the positive Doppler velocities (upward/northward) dominate in the upper E region echoes. The third is the daytime continuous echoes, which mainly occur from morning to nearly noontime (07:00LT—11:30LT) with reduced echo intensity and both positive and negative Doppler velocities. These low latitude E region echoes mainly are type-I!I, which is similar to that of the Equatorial Electrojet (EEJ) and mid-latitude regions, but their temporal behavior is evidently different from that of the latter two latitudes and also has some differences with that of the other low latitudes.
2013, 33(2): 213-218.   doi: 10.11728/cjss2013.02.213
Abstract(1743) [PDF 470KB](0)
Abstract:
The intelligent control problem of space-based manipulator system with bounded control torques and uncertain parameters is studied. According to the system's momentum conservation and Lagrange's equation, the system's dynamics equation is established. An adaptive control based on saturated velocity filter for space-based manipulator system with bounded control torques and uncertain payload parameters is developed. The proposed control scheme overcomes the influence of the uncertain parameters on the control accuracy by using adaptive controller; limits the control torques by using hyperbolic functions, which lets the control more realistic. And in the control process, it doesn't need to measure and feed back the system's velocity signal by using the velocity filter, which makes the control simpler. The simulation validates the effectiveness of the proposed control scheme.
2012, 32(5): 757-764.   doi: 10.11728/cjss2012.05.757
Abstract(2193) [PDF 558KB](1)
Abstract:
The robust control scheme based on velocity filter of free-floating dual-arm space robot system with uncertain payload parameters was studied. Through the Lagrangian approach, the dynamic equation of the free-floating space robot was modeled as under-actuated system. With the augmentation approach, it was demonstrated that the dynamic equations and the augmented generalized Jacobi matrix of the system can be linearly dependent on a group of inertial parameters, respectively. Based on the results, a robust controller based on velocity filter was developed for dual-arm space robot system with uncertain payload parameters to track the desired trajectories in inertial space. Ascribe to the pseudo-velocity signal acquired through the velocity filter, the proposed control scheme with only accurate positions of the joints and the end-effectors feedback avoid measuring the velocity and acceleration of the end-effectors. And it can avoid the control chatter effectively at the same time. The effect of the controller is testified by computer simulation.
2011, 31(6): 821-828.   doi: 10.11728/cjss2011.06.821
Abstract(2135) [PDF 606KB](0)
Abstract:
The trajectory tracking control for coordinated motion of free-floating space manipulator system with an attitude controlled base is discussed. According to the geometrical relationship and law of conservation of momentum, the dynamic equations of space manipulator system are constituted through Lagrange equation of the second kind. Based on the above, a fuzzy wavelet neural network scheme is designed to control the base attitude and the joint angle of manipulator to track desired trajectories synchronously in joint space on condition that system parameters are unknown. The control scheme needs neither linearly parameterize the dynamic equations of the system, nor know any system parameters. Further more, its network weights are learning online based on errors by back propagation algorithm so the self-learning and self-adapting ability of fuzzy neural network is enhanced and meantime the offline training time is saved. Numerical simulations are presented to verify the feasibility and effectiveness of the proposed control scheme.
2014, 34(1): 81-88.   doi: 10.11728/cjss2014.01.081
Abstract(1110) [PDF 2101KB](2)
Abstract:
The thermospheric densities at the altitude of 410km during the geomagnetic storm on Nov. 20—21, 2003 are calculated by NCAR-TIEGCM model, and the results are compared and analyzed with the observational data from CHAMP/STAR. The results show that the model can exactly represent the distribution and variation of the density during geomagnetic storm, and the model results have a good consistency with the CHAMP data in trends and orders. But some differences do exist in detailed structure and magnitude. The model underestimated the increases of the density during geomagnetic storm with the values of 100%～125%, instead of the 250%～400% observed by CHAMP. The deviations between the model and CHAMP at high latitude are bigger than those of low latitude, and dayside bigger than nightside. It is also found that the density disturbance during geomagnetic storm presents day-night asymmetry and Southern-Northern hemisphere asymmetry. The model can exactly represent the propagation of the density disturbance from high latitude to low latitude, and the time delay in response of the density to geomagnetic storm.
2014, 34(1): 95-103.   doi: 10.11728/cjss2014.01.095
Abstract(952) [PDF 1988KB](2)
Abstract:
The reflectance spectrum of space debris is the interactive result of the space debris material and the solar spectrum, which can reflect the material nature of space debris and provide the basis for studying the optical properties of space debris. In this paper, we preprocess the observed space debris images, extract debris spectral curves, correct spectral data of atmospheric turbulence and then compare the actually observed reflectance spectra of space debris with the known space material reflectance spectra. The optical properties differences between them, such as peak, slope, shape, narrow band characteristics, absorption lines in the continuous reflectance spectrum curve and imaging differences, color indices, characteristic temperature in multiband can be analyzed. Then the space debris can be distinguished from others by its surface materials finally.
2014, 34(5): 648-668.   doi: 10.11728/cjss2014.05.648
Abstract(963) [PDF 2012KB](3)
Abstract:
In this national biannual report, we will outline some recent progresses in ionospheric studies conducted by Chinese scientists since 2012. The mentioned aspects include: the solar activity control of the ionosphere; couplings between the ionosphere, lower atmosphere and plasmasphere; ionospheric climatology and disturbances; ionospheric irregularities and scintillation; models, data assimilation and simulations; unusual phenomena of the ionosphere; possible seismic signatures presented in ionospheric observations, and some methodology progresses. These progresses will enhance our ability to observe the ionosphere, provide more reasonable understanding about the states of the ionosphere and underlying fundamental processes, and stimulate ionospheric modeling, forecasting and related applications.
2014, 34(5): 721-732.   doi: 10.11728/cjss2014.05.721
Abstract(892) [PDF 155KB](0)
Abstract:
Human beings are now facing global and regional sustainable development challenges. In China, Earth observation data play a fundamental role in Earth system science research. The support given by Earth observation data is required by many studies, including those on Earth's limited natural resources, the rapid development of economic and social needs, global change, extreme events, food security, water resources, sustainable economic and urban development, and emergency response. Application operation systems in many ministries and departments in China have entered a stage of sustainable development, and the State Key Project of High-Resolution Earth Observation Systems has been progressing since 2006. Earth observation technology in China has entered a period of rapid development.
2009, 29(1): 39-44.   doi: 10.11728/cjss2009.01.039
Abstract(3140) [PDF 723KB](4)
Abstract:
Flywheel has been identified as one of the main disturbance sources that affect the precision of attitude control system of spacecraft. In this paper, the main sources of vibration disturbances from flywheels were analyzed. The disturbance measuring technology used by some research centers were introduced and reviewed, which included NASA Goddard Space Flight Center, Tsukuba Space Center of the National Space Development Agency of Japan and MIT Space Systems Laboratory. This paper is helpful for establishing flywheel disturbance measuring system.
1991, 11(3): 168-175.   doi: 10.11728/cjss1991.03.168
Abstract(1558) [PDF 535KB](3)
Abstract:
Acombined scheme is developed to solve the ideal MHDequations. Keeping certain precision, this model has ensured stability and small computing capacity. Atwo-dimensional hemlet-streamer solution of the meridian solar wind near the sun is obtained. Using this solution as initial state, the effect of the hemlet-streamer configuration on the propagation of coronal mass ejections is investigated. It is found that the configuration deflects the ejected mass toward equator. This effect can explain some observational results satisfactorily.
2012, 32(6): 897-902.   doi: 10.11728/cjss2012.06.897
Abstract(2116) [PDF 515KB](2)
Abstract:
The model and kinematics equations of a floating redundant spatial robotic manipulator are established. The Jacobian matrices are analyzed, and the inverse kinematics is obtained. Chaotic motions which existed in the floating spatial redundant robotic manipulator's self-motions are proved by simulation. At last, a spatial 3R redundant robotic manipulator is taken as an example, and the links' self-motion has been studied when the end-effector tracking a plane path repeatedly in its workspace for PD controlling by analysis of direct observation, time history method, phase diagram method, and poincare mapping method. Results show that there exist chaotic motions in the self-motion of the floating spatial redundant robotic manipulator when solving the floating redundant robotic manipulator's inverse kinematics based on pseudo-inverse Jacobian matrix.
2012, 32(1): 147-153.   doi: 10.11728/cjss2012.01.147
Abstract(1924) [PDF 572KB](2)
Abstract:
The joint motion control and vibration suppression problems of rigid-flexible space robot with an attitude controlled base were discussed. With Lagrangian method and singular perturbation theory, the singular perturbation model of the system was derived. To guarantee the accurate coordinated motion control of the base attitude and the arm's joints under the effects of unknown system parameters, the compensation control strategy based on Radial Basis Function (RBF) neural network was proposed for the slow subsystem. Simultaneously, the linear quadratic optimal controller was given for the fast subsystem to suppress the elastic vibration of the system. Simulation results demonstrate that the presented control scheme can effectively compensate for the influence of unknown system parameters, and control the system to track the desired trajectory and suppress the elastic vibration preferably.
2015, 35(4): 495-501.   doi: 10.11728/cjss2015.04.495
Abstract(996) [PDF 6225KB](5)
Abstract:
2014, 34(1): 24-28.   doi: 10.11728/cjss2014.01.024
Abstract(1086) [PDF 469KB](1)
Abstract:
The open magnetic flux (Fpc) is a key parameter to study magnetospheric dynamical process, which is closely related to magnetic reconnections in the dayside magnetopause and magnetotail. The dayside reconnection rate controls the amount of the open magnetic flux, which is affected by various solar wind parameters, among which the clock angle θc of the interplanetary magnetic field (IMF) is an important factor that influence the dayside reconnection rate. Using global MHD simulations, we analyze the relationship between θc and Fpc. The results show that the open flux Fpc increases as the clock angle θc approaches 180°(due southward), and the open flux Fpc is proportional to sin3/2 (θc/2). This reflects the physical connection between them, since θc describes the magnitude of the shear between IMF and terrestrial magnetic field, and affects the dayside reconnection rate, thus controlling the open flux Fpc.
2014, 34(5): 558-562.   doi: 10.11728/cjss2014.05.558
Abstract(918) [PDF 253KB](1)
Abstract:
The Experimental Satellite on Electromagnetism Monitoring (ESEM) was proposed in 2003 and proved in 2013 after 10-years' scientific demonstration. The ESEM mission was proposed to be the first satellite of space-based geophysical fields observation system in China with a lot of application prospects in earthquake science, geophysics, space sciences and so on. And coincide with the mission objectives, the satellite decides to use the Circular Sun Synchronous Orbit with an altitude of 507km and descending node time at 14:00LT. The payload assemble includes 8 instruments, Search-Coil Magnetometer, Electric Field Detector, High precision Magnetometer, GNSS occupation Receiver, Plasma Analyzer, Langmuir Probe, Energetic Particle Detector, and Three-frequency Transmitter. According to the planned schedule, the satellite is due to be launched in 2016-2017 and will be onboard operated for 5 years.
2009, 29(1): 1-6.   doi: 10.11728/cjss2009.01.001
Abstract(4992) [PDF 610KB](1)
Abstract:
Upper atmospheric wind and temperature are important basic parameters. Its global high-precision measurement has broad prospects for various applications, so the strong demand to explore them is growing the interferometric spectrometer is characterized with multi-channel, high-throughput and high spectral resolution, it becomes the optimum choice for detecting upper atmospheric wind and temperature. The current successful application of the interferometric spectrometer has two kinds, Fabry-Perot interferometer and wide angle Michelson interferometer. The paper mainly reviews the interferometric spectrometers used in the upper atmosphere wind and temperature field exploration, analysis and compares the feasibility of several interferometers measurement of wind and temperature and their respective advantages and disadvantages. These work lays a foundation for our future on-board detection in China.
2014, 34(5): 710-720.   doi: 10.11728/cjss2014.05.710
Abstract(1099) [PDF 13852KB](1)
Abstract:
During 2012 and 2014, China has two Haiyang (which means ocean in Chinese, referred to as HY) satellites operating normally in space which are HY-1B and HY-2A. HY-1B is an ocean color environment satellite which was launched in April 2007 to observe global ocean color and sea surface temperature, and HY-2A is an ocean dynamic environment satellite which was launched in August 2011 to obtain global marine dynamic environment parameters including sea surface height, significant wave height, ocean wind vectors, etc. Ocean observation data provided by HY-1B and HY-2A have been widely used by both domestic and international users in extensive areas such as ocean environment protection, ocean disaster prevention and reduction, marine environment forecast, ocean resource development and management, ocean investigations and scientific researches, etc.
1993, 13(2): 159-162.   doi: 10.11728/cjss1993.02.159
Abstract(2670) [PDF 329KB](1)
Abstract:
The rat tail-suspension model may be more acceptable for simulating weightlessness than other animal models in the view of its less stressful situation. However, there are problems of injury to the skin and development of abscesses and ischemic necrosis of the tail. Inorder to minimize this traumatic nature of the technique and make longer the suspension period, modifications are made to the Morey-Holton and Wronski's tail-suspension method. The main points are as following: (1) Apart from tincture of Benzoin, tincture of resin is spracyed on the tails, which help to unsmooth the tail surface and firm the attachment of the adhesive tape stripes. (2) The taping places on the tail are changed regularly every 7 days. For this reason, the tail surface is divided into four sides and only two opposite ones (upper and below or left and right) are applied with tape stripes, leaving the other two unattached for the later taping place replacement. (3) The traction force acting on the tail is mainly carried by the tape stripes attached longitudinally with the tail rather than those twining around the tail. These modifications effectively protected the tail from ischemic injures caused by the surrounding tape stripes either by the force acting on the tail or the constriction of the tail as the rat grows. The skin injuries by the irritation or tearing of the tape strips rarely happened and could recovery soon after the taping place replacement. The modified tail-suspension is well tolerated by five groups of male SDstrain rats (10 animals per group)for 90 to 120 days, as evidenced by normal feeding, normal grooming behavier and a continued weight gain kept close to or almost same as that of pair-fed control groups hroughout the suspension period. So it may be a useful model for simulating the effects of long-term weightlessness.
2012, 32(6): 874-880.   doi: 10.11728/cjss2012.06.874
Abstract(2267) [PDF 526KB](3)
Abstract:
In allusion to the problem that the aircraft autonomous celestial navigation is not suitable for the near space vehicles with hypersonic speed, an approach of the autonomous celestial navigation of near space vehicles with hypersonic speed based on non-Keplerian orbits is studied. Mechanism of the autonomous celestial navigation based on non-Keplerian is analyzed, and the dynamic equations are developed by analyzing the strength of near space vehicles with hypersonic speed. The space motion equation is educed using the vector derivatives rules. States model based on non-Keplerian orbits and measurement model using the concept of stellar horizon atmospheric refraction are designed, and the Kalman filter simulation is adopted. Results show that the autonomous celestial navigation of near space vehicles with hypersonic speed based on non-Keplerian orbits can meet the requirement of high precision for position and velocity, which is important for further research on the near space vehicles with hypersonic speed.
1995, 15(1): 73-76.   doi: 10.11728/cjss1995.01.073
Abstract(1839) [PDF 271KB](6)
Abstract:
Using the NIMBUS-7 SAMS GRID-T data,the variations of the middle atmosphere temperature induced by solar flare events classed larger than 3.5 during 1979-1982 is discussed. The results show that the temperature of the upper mesosphere is obviously decreased and that, of the lower mesosphere is obviously increased,while the stratospheric temperature does not varies obviously,within sevaral days around the Ha flare bursts day.
2014, 34(5): 535-543.   doi: 10.11728/cjss2014.05.535
Abstract(1063) [PDF 7143KB](0)
Abstract:
To develop an understanding of near-Earth space's response to solar activities and the coupling among different layers in geospace, China has initiated a ground base program to monitor China's geospace environment called the Meridian Space Weather Monitoring Project (Chinese Meridian Project). The effort consists of a chain of 15 ground-based observatories located roughly along 120°E longitude and 30°N latitude. Each observatory is equipped with multiple instruments to measure key parameters such as the baseline and time-varying geomagnetic field, as well as the middle and upper atmosphere and ionosphere from about 20 to 1000 kilometers. This project started collecting data in 2012. We will give a brief introduction to the Chinese Meridian Project, and present recent scientific results mainly in ionospheric and atmospheric studies.
2014, 34(5): 733-739.   doi: 10.11728/cjss2014.05.733
Abstract(685) [PDF 105KB](1)
Abstract:
Advances of microgravity sciences in China are introduced. The research works include ground-based study and space experiments. In the recent years, the main means still are theoretical analysis, numerical simulation, ground-based experiment, and short-time microgravity experiments of drop tower. Besides, many space experiment projects are arranged. SJ-10 recoverable satellite will carry out 19 scientific experiment projects. Nine of them are for microgravity Sciences. The other ways for space microgravity experiment are with the help of Chinese Shenzhou spacecraft, Chinese Tiangong space laboratory, and Chinese space station in the near future. The Chinese space station will become main platform of Chinese microgravity sciences experiment in space.
2016, 36(5): 620-625.   doi: 10.11728/cjss2016.05.620
Abstract(954) [PDF 122KB](1)
Abstract:
The Chinese Meridian Space Weather Monitoring Project (Meridian Project for short) is a ground-based geospace monitoring chain in China. It consists of a chain of 15 ground-based observatories located roughly along 120°E longitude and 30°N latitude. Each observatory is equipped with multiple instruments to measure key parameters such as the baseline and time-varying geomagnetic field, the middle and upper atmosphere and ionosphere from about 20 to 1000km. This project started collecting data in 2012. Here a brief overview of the Chinese Meridian Project is given, and most recent science results mainly in the ionospheric and atmospheric studies are presented.
2018, 38(5): 650-655.   doi: 10.11728/cjss2018.05.650
Abstract(948) [PDF 556KB](21)
Abstract:
China plans to implement the first Mars exploration mission in 2020. It will conduct global and comprehensive exploration of Mars and high precision and fine resolution detection of key areas on Mars through orbiting, landing and roving. The scientific objectives include studying the Martian morphology and geological structure characteristics, studying the soil characteristics and the water-ice distribution on the Martian surface, studying the material composition on the Martian surface, studying the atmosphere ionosphere and surface climate and environmental characteristics of Mars, studying the physical field and internal structure of Mars and the Martian magnetic field characteristics. The mission equips 12 scientific payloads to achieve these scientific objectives. This paper mainly introduces the scientific objectives, exploration task, and scientific payloads.
2012, 32(2): 270-276.   doi: 10.11728/cjss2012.02.270
Abstract(2789) [PDF 573KB](4)
Abstract:
Aerospace and extra-terrestrial applications on SRAM FPGA are sensitive to SEU which might result in information loss or functional interruption. In this paper, a detailed introduction to TMR and Scrubbing, which are the significant techniques of this design, was given; then, a highly reliable fault-tolerant system based on TMR, Scrubbing and Reload rules was implemented. An anti-fuse FPGA periodically scrubbed the configuration bitstream of SRAM FPGA in milliseconds level, and both FPGAs implemented triple module design redundancy. This fault-olerant design has been adopted in an actual spacecraft electronic system, which can make reference to the design of highly reliable electronic systems.
2014, 34(4): 377-383.   doi: 10.11728/cjss2014.04.377
Abstract(1037) [PDF 2554KB](0)
Abstract:
The difference between Martian atmosphere and Earth atmosphere results in the different flow field and property around the entry vehicles, and the possible change of aerodynamic characteristic on account of chemical non-equilibrium will differ from that in Earth re-entry process. The differences between Martian and Earth atmosphere include species, density and temperature. Three-dimensional Navier-Stokes equations coupling real gas model are solved by a parallel code to analyze the change of aerodynamic characteristic of Mars Science Laboratory (MSL) introduced by CO2 effect as well as the uncertainty of density and temperature in hypersonic entry phase of Entry-Descending-Landing procedure when MSL entering the Martian atmosphere. The results show that the computational data of Viking based on current Martian atmosphere model and numerical methods has a good agreement with both the flight data and LAURA results. Gas species in the model, which are mainly CO2 for Mars, have a great influence on the drag and pitching moment coefficients compared to the air model of Earth, so CO2 correction should be considered while the aerodynamic data is derived from air. Increase of the density in atmosphere model enhances chemical non-equilibrium effect, but produces no distinctness for aerodynamic characteristic; increase of the temperature improves chemical non-equilibrium effect greatly, and has a small influence on aerodynamic characteristic.
2018, 38(1): 6-6.
Abstract(766) [PDF 339KB](3)
Abstract:
2016, 36(5): 639-671.   doi: 10.11728/cjss2016.05.639
Abstract(820) [PDF 355KB](2)
Abstract:
Great progress has been made in the research of solar corona and interplanetary physics by the Chinese scientists during the past two years (2014-2016). Nearly 100 papers were published in this area. In this report, we will give a brief review to these progresses. The investigations include:solar corona, solar wind and turbulence, superhalo electron and energetic particle in the inner heliosphere, solar flares and radio bursts, Coronal Mass Ejections (CMEs) and their interplanetary counterparts, Magnetohydrodynamic (MHD) numerical modeling, CME/shock arrival time prediction, magnetic reconnection, solar variability and its impact on climate. These achievements help us to better understand the evolution of solar activities, solar eruptions, their propagations in the heliosphere, and potential geoeffectiveness. They were achieved by the Chinese solar and space scientists independently or via international collaborations.
1987, 7(1): 73-77.   doi: 10.11728/cjss1987.01.073
Abstract(1800) [PDF 357KB](7)
Abstract:
In this paper the results of thermoluminecence (TL) study on Bo County meteorite are reported. Temperature gradient in the meteorite, produced by heating during its atmospheric passage, is 34.2°C/mm in head, 24.8°C/mm in side. The temperature profiles of the meteorite is closed to the Barwell meteorite, and more reasonably consistent with the steady-state solution to the heat conductivity equation in a case of the ablation rate of 0.10 cm/sec. According to the TLcurve of the meteorite the parameter Ln (LT/HT) is 1.30. So the meteorite belong to type A.
2013, 33(6): 629-636.   doi: 10.11728/cjss2013.06.629
Abstract(1298) [PDF 5097KB](2)
Abstract:
Auroral substorm is a basic energy input, coupling and dissipation process. Complex auroral substorm effects are not to be neglected for the thermospheric neutral wind effects, and has important significance on its in-depth study. A self-developed all-sky Fabry-Perot Interferometer (FPI) has been deployed by Chinese Arctic Yellow River Station (78.92°N, 11.93°E) at Ny-Alesund, Svalbard in November 2010, and formal observation has been carried out, which obtained FPI measured data for the first time in domestic. This paper briefly introduces the observations during winter in 2012. Two auroral substorm events on November 12-14, 2012 and December 9-11, 2012 were selected for data processing, and wind fields corresponded to 5 interference rings were calculated. The comparison and analysis between wind field and geomagnetic activity variations during the periods of auroral substorms indicated that the dramatic change of wind speed may be caused by a violent disturbance of geomagnetic activity. Contrastive analyses between auroral images by an all sky camera and FPI interference fringes corresponding line of sight wind field during November 13, 2012, 00:00UT-02:00UT and December 10, 2012, 05:00UT-07:30UT suggest that the enhanced direction is perpendicular to the aurora arc, and it weakens in the direction paralleled with the arc.
2009, 29(1): 150-153.   doi: 10.11728/cjss2009.01.150
Abstract(4330) [PDF 582KB](2)
Abstract:
Surface tension is one of the most important physical chemistry parameters in material field. Many interface phenomena under microgravity attract scientists and need farther study. Sessile drop method is the main way to measure surface tension of melts, which works well on the earth. However, it is difficult to be used under microgravity environment. The paper expresses new cognition about measurement after thinking of the theory of surface tension, and discusses the difficulty of using sessile drop method under microgravity environment. This paper introduces levitation method to measure the surface tension, especially the electromagnetic levitation method, which avoids the error brought by vessel contacting. Under microgravity environment, the electromagnetic levitation method can improve the measurement precision.
2014, 34(5): 757-764.   doi: 10.11728/cjss2014.05.757
Abstract(916) [PDF 1493KB](0)
Abstract:
During 2012-2014, the main research activities from microgravity material research were focused on, which include study of microgravityeffects on collagen fibrillogenesis and HAP crystallization, microgravity experiments using drop tube, and research of thermoelectric materials for space. This paper summarizes all these activities.
2013, 33(6): 604-607.   doi: 10.11728/cjss2013.06.604
Abstract(944) [PDF 498KB](4)
Abstract:
Based on AMS-01 experiment, the integral fluxes and the energy spectra are investigated for the estimation of background cosmic ray radiation. Using the data from AMS-01 experiment in the Sun quiet phase of June 1998, the integral fluxes of primary protons for the kinetic energy ranges of 0.44～4.31GeV, 4.31～12.38GeV, 12.38～199.06GeV near the Earth at geomagnetic latitude of Yangbajing are achieved respectively. And the integral fluxes of primary for the kinetic energy ranges of 6.92～14.45GV and 14.45～229.9GV are also obtained. Correspondingly, the energy spectra functions for the protons and helium are then fitted for this 5 energy ranges, separately. The integral fluxes for the same energy range above is consistent by the two methods of approximate calculation of integral and the integral of function curves.
2014, 34(5): 516-517.   doi: 10.11728/cjss2014.05.516
Abstract(2515) [PDF 61KB](9)
Abstract:
Focusing on the key scientific questions of deep space exploration which include the origin and evolution of the solar system and its planets, disastrous impact on the Earth by the solar activities and small bodies, extraterrestrial life, this paper put forward a propose about the roadmap and scientific objectives of China's Deep-space Exploration before 2030.
1998, 18(4): 348-355.   doi: 10.11728/cjss1998.04.348
Abstract(1881) [PDF 474KB](0)
Abstract:
The exploring satellite which operates on the high eccentricity orbit has many orbital characteristics. In this paper, SJ-4 satellite is taken as an example to discuss some features in satellite designed general operation, and the emphasis is put on the main characteristics of orbit design, and shows the data and figures which stand for orbital calculation, window, satellite's launching illumination and tracking conditions. It is pointed out that the accuracy of orbit design and initial attitude selection of the SJ-4 satellite has verified by the telemetric data in two months operation.
2010, 30(5): 468-473.   doi: 10.11728/cjss2010.05.468
Abstract(2453) [PDF 490KB](2)
Abstract:
Chinese meteorological satellite, Fengyun (FY) Satellite, has a polar-orbiting series and a geostationary series. Up to now, 5 polar-orbiting (FY-1A/B/C/D and FY-3A) and 5 geostationary (FY-2A/B/C/D/E) satellites were launched. FY data has been being intensively applied not only to meteorological monitoring and prediction but also to many other fields regarding ecology, environment, disaster, space weather and so and. The FY data sharing system, FengyunCast, is now one of the three components of global meteorological satellite information dissemination system, GEONETCast. The first satellite of the new generation polar-orbiting series, FY-3A, was launched on 27 May, 2008, demonstrating the FY polar-orbiting satellite and its application completed a great leap to realize three-dimensional observations and quantitative application. The first of the next generation geostationary series (FY-4) is planned to launch in 2014.
2016, 36(2): 209-214.   doi: 10.11728/cjss2016.02.209
Abstract(1214) [PDF 849KB](7)
Abstract:
The payload of the satellite has different working modes. In order to obtain the optimum working state, it needs to be switched constantly between each mode. When switching, many working state parameters need to be configured, such as, 28 Front Electronic Ends (FEE), neutron acquisition and processing circuit, the trigger system circuit, high voltage powers and payload data management system. To improve the switch flexibility of payload exploration mode and lower the complexity of parameter configuration during switching, the management project is studied for payload self-exploration of the satellite by analyzing the working modes of this explorer. The designing method is based on event-driven which are combined by programming-experts on the ground and perform-units on the satellite. Software realization result is given out for the payload self-exploration. Meanwhile, the reliability and security measures are studied. The test results show that the function is implemented. It can be used on the satellite to explore space anytime and anywhere. It reduces the dependency on the remote control center.
2012, 32(2): 238-244.   doi: 10.11728/cjss2012.02.238
Abstract(1768) [PDF 217KB](0)
Abstract:
Responsive orbits have exhibited advantages in emergencies for their excellent responsiveness and coverage to targets. Generally, there are several conflicting metrics to trade in the orbit design for responsive space. A special multiple-objective genetic algorithm, namely the Nondominated Sorting Genetic Algorithm Ⅱ (NSGAⅡ), is used to design responsive orbits. This algorithm has considered the conflicting metrics of orbits to achieve the optimal solution, including the orbital elements and launch programs of responsive vehicles. Low-Earth fast access orbits and low-Earth repeat coverage orbits, two subtypes of responsive orbits, can be designed using NSGAⅡ under given metric tradeoffs, number of vehicles, and launch mode. By selecting the optimal solution from the obtained Pareto fronts, a designer can process the metric tradeoffs conveniently in orbit design. Recurring to the flexibility of the algorithm, the NSGAⅡ promotes the responsive orbit design further.
2014, 34(1): 127-136.   doi: 10.11728/cjss2014.01.127
Abstract(1528) [PDF 721KB](4)
Abstract:
It is a problem to miniaturize space avionics when we use traditional 1553B bus interface chips. To solve this problem, design of an ASIC chip for spacecraft integrated avionics is proposed. The design of a 1553B IP core with independent intellectual property in this chip is described in detail. The 1553B IP core includes the bus controller module, the remote terminal module, the Manchester decode and encode module, the shared RAM, the RAM arbitration module, the AXI bus slave interface module, the channel select module and the timer module. Each module is introduced. The top-down designing method is used and the program is described by Verilog hardware description language. The 1553B IP core design is tested and verified by the functional simulation, the ASIC system simulation and FPGA test. DDC's 1553B test board is used to test the IP core. The test results indicate that the 1553B IP core design is reasonable. The design of 1553B IP core has good performance in reliability, portability, real-time and less resource occupancy.
2017, 37(6): 675-689.   doi: 10.11728/cjss2017.06.675
Abstract(740) [PDF 4698KB](4)
Abstract:
Flux Transfer Events (FTEs) observed at the Earth's magnetopause are generally believed to be products of transient and patchy magnetic reconnection processes, serving as linkage channels between solar wind and Earth's magnetosphere and therefore playing a crucial role in the exchange of mass, momentum, and energy between these two regions. Magnetic field reconstruction techniques are useful for better understanding FTE's formation and evolution and its interaction with surrounding environment. Traditional techniques such as Grad-Shafranov reconstruction and FTE model fitting methods, however, are confined to specific physical conditions. A new multi-point method applicable to two-dimensional FTEs in various physical condition is devised based on plane linear interpolation. The applications to two FTEs observed by THEMIS and Cluster show that the method can quickly and efficiently reconstruct the spatial distribution of the magnetic field structure, and will help to infer the magnetic field line configurations, understand the temporal variation of measured data and analyze the spatial distribution characteristic of plasma parameters relative to the magnetic field.
1998, 18(1): 39-51.   doi: 10.11728/cjss1998.01.039
Abstract(1691) [PDF 610KB](6)
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.
2014, 34(1): 89-94.   doi: 10.11728/cjss2014.01.089
Abstract(986) [PDF 587KB](7)
Abstract:
An inversion method is introduced to study the variations of the ballistic coefficient for orbital satellites with different geometrical characteristic. Using satellite tracking data and NRLMSISE00 empirical model of the atmosphere, ballistic coefficients B of the selected satellites are compiled out with this new method. The "true" values of B (Bt) were computed by averaging the 31 years of B values obtained for each satellite. These true B values were validated by comparing the Bt values of two spheres and by comparing the Bt values obtained for a pair of satellites having very similar size, shape and mass. The estimated ballistic coefficients B' variations for a number of selected satellites were then averaged over each year, and compared with solar indices. Some interesting results are found. Firstly, there does not appear to be a bias in the Bt values computed using the 31 years' time period. Secondly, the large similarity between the time series of B ratios is apparent and solar activity related variations in the thermosphere increase in amplitude with increasing height, as do the errors in the NRLMSISE00 model. Thirdly, the anti-correlations of B' variations with the F10.7 variations were found in short periods. Finally, the NRLMSISE00 model has failed to produce the low thermospheric density during the 2008 solar minimum. The variations in B' point out that the scaling factor is required to correctly predict the true densities from empirical atmosphere models, especially in solar maxima and minima. It is also shown that changes in B ratios during some major geomagnetic storms cannot be explained by atmosphere model.
2014, 34(2): 226-234.   doi: 10.11728/cjss2014.02.226
Abstract(1119) [PDF 1137KB](4)
Abstract:
Demonstrator of Full Polarization Interferometric Radiometer (FPIR) is a one dimensional microwave interferometric radiometer with high resolution, light weight and low power consumption at X-band. The theory of polarimetry is analyzed to deduce the polarimetric visibility function in FPIR. To obtain the full polarimetric information, two kinds of different antenna arrays are designed in the FPIR system. Corresponding optimal polarization switching sequence for each sparse antenna array is also designed. The minimum degradation in sensitivity is achieved and sensitivities of the horizontal, vertical, and complex cross brightness temperatures are the same in the polarimetric mode of FPIR with the polarization switching sequence.
2014, 34(3): 332-340.   doi: 10.11728/cjss2014.03.332
Abstract(1206) [PDF 1987KB](3)
Abstract:
Four scientific instruments are selected as the payloads for Chinese Chang'E-3 Lunar rover, including panoramic cameras, lunar radar, IR acousto-optic spectrometer, X-ray spectrometer. Panoramic cameras are to acquire the stereo optical image of lunar surface topography around the lunar rover. Lunar radar explores the lunar regolith thickness and structure. IR acousto-optic spectrometer obtains the IR spectrum and image of lunar surface, which can be used to analyze the lunar surface's mineral composition and distribution. X-ray spectrometer analyzes the content of the lunar surface rock to get the rock elements composition. In this paper, Chang'E-3 Lunar rover's scientific exploration objectives, the scientific payload's components and system design are mainly introduced. Each payload's design and main technical index are also described in detail.
2014, 34(4): 398-405.   doi: 10.11728/cjss2014.04.398
Abstract(998) [PDF 5503KB](1)
Abstract:
There are important effects on the electron equipments for the variations of ionosphere, such as it can induce shortwave communications quality decline indeed interrupted, navigation signal scintilla and error increase, space craft orbit change, surface charging up and proton event etc. In a word, it is important to study ionospheric characteristic and its impaction on electronic equipments. Based on Urumchi ionospheric vertical sounders and its more than fifty years data, the daily variations, seasonal changes and long-term trends of the ionosphere over Urumchi were studied. Some meaningful conclusions are given at the end of the paper.
1984, 4(4): 324-330.   doi: 10.11728/cjss1984.04.324
Abstract(2124) [PDF 553KB](3)
Abstract:
In this paper, the author put his emphasis to the importance of brain science research in space flight based, on the flight experinces and laboratory investigationsdur-ing the past twenty years. The theories and techniques developed in author's laboratory for astronaut brain function research are briefly summerized. The viewpoints on brain evolution in the gravitational field, the principle of frontalization of brain function and the problem of extraterrestrial intelligence are also stressed. Finally, a space brain science research program is suggested.
1997, 17(4): 337-342.   doi: 10.11728/cjss1997.04.337
Abstract(1474) [PDF 413KB](2)
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 hm 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 hm is presented.
2017, 37(5): 531-537.   doi: 10.11728/cjss2017.05.531
Abstract(1470) [PDF 2062KB](2)
Abstract:
Compared with vertical heating, oblique ionospheric heating has advantages of higher flexibility, wider effect range and more practicable operability. In this paper, based on the energy conservation equation and continuity equation of electron, the physical model is built for lower ionosphere heated by oblique radio wave by considering Ohm absorption in the non-deviated section, and oblique heating in low ionosphere over Nanjing district is simulated using the background parameters obtained by IRI-2007 and NRLMSISE-00 models. The results show that heating effect increases when incident elevation angle and effective radiated power increase. The rising amplitude of electronic temperature and density decreases when the frequency of radio wave increases. The perturbation amplitudes of electron temperature and density caused by X mode are bigger than those caused by O mode, and X mode can make electron temperature and electron density reach a steady state more quickly than O mode. Within a certain range, the radio wave with smaller incident elevation angle, lower frequency and larger effective power can make electron density reach a steady state more quickly, and the latter two can also accelerate the process of electron temperature to reach stability. The time that electron temperature to reach stability varies singlet with elevation angle of incident electromagnetic wave, and will be a maximum as the elevation angle is 62°.
2003, 23(2): 149-154.   doi: 10.11728/cjss2003.02.149
Abstract(1753) [PDF 1330KB](1)
Abstract:
2015, 35(3): 336-342.   doi: 10.11728/cjss2015.03.336
Abstract(818) [PDF 5777KB](2)
Abstract:
The facility for combustion experiments in space is lightweight, small sized and multi-functional. In this paper, a prototype system used for flame structure display and temperature measurement is presented, which combined the schlieren method, rainbow schlieren deflection method and differential interference method. It is also lightweight and small sized. As for the prototype system, the flame structure display function was checked by schlieren method in microgravity drop tower, and the temperature measurement function was checked by rainbow schlieren deflection and differential interference method under normal gravity condition. Results show that the resolution of flame structure was not less than 1mm, and temperature field measurement was accurate with relative error smaller than 2%. Such prototype system is important to the promotion of space combustion science experiment technology and will be beneficial to the future combustion experiments in space.
2014, 34(2): 160-167.   doi: 10.11728/cjss2014.02.160
Abstract(1097) [PDF 643KB](3)
Abstract:
Accurately determining critical frequency and propagation factor of ionosphere was important to frequency forecast and management of short-wave communication. Oblique sounder provide a valid method for real-time observation of it. A new practicable method was presented for determining f0F2 and M(3000)F2 at the path midpoint from the oblique sounding data, which was based on simple oblique ray theory and only rely on maximum observation frequency and its propagation delay. The inversion from oblique sounding data on the Changchun-Jingyang and Xinxiang-Chifeng path, were compared with the vertical sounding data in Beijing during October 2009. According to analysis, the stability, accuracy and practicability of the new method are validated. The results show that the root-mean-square error of the new inverse method is 0.48MHz, and the relative root-mean-square error is 10.50%. It is obvious that the new inverse method is better than Smith's method and reference ionosphere of China. Moreover, the method is simple and easy to use. It provides the basis for frequency forecast and management of short-wave communication, and help to know ionospheric variational characteristics.
2012, 32(2): 265-259.   doi: 10.11728/cjss2012.02.265
Abstract(2280) [PDF 400KB](1)
Abstract:
A Bayesian reliability assessment method for spaceflight electronic device is put forward. The method combines the reliability information of the whole system and its subsystems. At first, the maximum entropy method is used to syncretize reliability information of subsystems; then the calculation formulas of moments of system reliability are deduced from reliability moments of subsystems and inheritance factor is determined and mixed Beta distribution is built; finally, the posterior distribution is used to assess system reliability. With the new method, the reliability of a spaceflight electronic device is evaluated to reach 0.9991 under the confidence level 0.70 with 240 whole system tests which is one-fifth of system tests needed by the classical method. It is feasible to use the new method to assess reliability of spaceflight electronic device.
2011, 31(5): 549-566.   doi: 10.11728/cjss2011.05.549
Abstract(2252) [PDF 1416KB](7)
Abstract:
The Sun continually radiates electromagnetic wave and particles to Earth, and the solar radiation is the main energy resource for the Earth’s climate system. The response of climate system to the solar variation is very complex, including radiative process, dynamic process and microphysics process. This paper reviews the measurements from satellites and reconstruction results by other proxies of the solar irradiance variation, enumerates some climate observational evidence in the fields of paleoclimate, temperature, atmospheric circulations and clouds affected by the solar activity. The three main possible mechanisms by which the solar variation may influence the global climate include: the variability of total solar irradiance could change the earth surface temperature, and thus change the atmospheric circulation via the ocean-atmosphere couple; the solar ultra violet radiations modulate the stratospheric temperature and wind field by heating ozone, and the stratosphere response could then affect the lower troposphere by stratosphere troposphere coupling; the solar modulates galactic cosmic ray through interplanetary magnetic field, and galactic cosmic ray may change the cloud cover via ionizing the atmosphere, which could further change the earth’s energy budget.
2013, 33(6): 577-603.   doi: 10.11728/cjss2013.06.577
Abstract(917) [PDF 1784KB](0)
Abstract:
In this review, we discuss the structure and dynamics of the magnetospheric Low-Latitude Boundary Layer (LLBL) based on recent results from multi-satellite missions Cluster and Double Star. This boundary layer, adjacent to the magnetopause on the magnetospheric side, usually consists of a mixture of plasma of magnetospheric and magnetosheath origins, and plays an important role in the transfer of mass and energy from the solar wind into the magnetosphere and subsequent magnetospheric dynamics. During southward Interplanetary Magnetic Field (IMF) conditions, this boundary layer is generally considered to be formed as a result of the reconnection process between the IMF and magnetospheric magnetic field lines at the dayside magnetopause, and the structure and plasma properties inside the LLBL can be understood in terms of the time history since the reconnection process. During northward IMF conditions, the LLBL is usually thicker, and has more complex structure and topology. Recent observations confirm that the LLBL observed at the dayside can be formed by single lobe reconnection, dual lobe reconnection, or by sequential dual lobe reconnection, as well as partially by localized cross-field diffusion. The LLBL magnetic topology and plasma signatures inside the different sub-layers formed by these processes are discussed in this review. The role of the Kelvin-Helmholtz instability in the formation of the LLBL at the flank magnetopause is also discussed. Overall, we conclude that the LLBL observed at the flanks can be formed by the combination of processes, (dual) lobe reconnection and plasma mixing due to non-linear Kelvin-Helmholtz waves.
1996, 16(3): 208-215.   doi: 10.11728/cjss1996.03.208
Abstract(1772) [PDF 581KB](6)
Abstract:
The cytstal growth of proteins and other biomacromolecules is an important study in space science'Using tube-like vapour diffusion apparatus made in China,two missions of protein crystallization have been carried out on Chinese re-entry satellites.52% and 80% of 48 samples prepared by 10 different kinds of proteins yielded crystals in the two space experiments respectively,and among them,a few of the proteins preduced better-quality Crystals.The results of the two missions show that the microgravity environment in space benefits improvement of protein crystal growth, and in the case with good enough optimized crystallization conditions,the space-grown protein crystals have larger size,better morphology and higher intend order than the Earth-grown crystals of the same protein.The effect of microgravity on protein crystal growth and its exploitation are also discussed in the paper.
2003, 23(2): 127-134.   doi: 10.11728/cjss2003.02.127
Abstract(1878) [PDF 1610KB](3)
Abstract:
2009, 29(1): 93-97.   doi: 10.11728/cjss2009.01.093
Abstract(4074) [PDF 559KB](4)
Abstract:
Relative to other space missions, space microgravity experiments have such charachteristics as dispersed users, real-time or near real-time process control requirement in experiments, a variety of processing requirements for space scientific data, etc. A framework assumption of ground system platform is proposed, according to the characteristics of space scientific experiments and the requirements for its ground support system, considering some finished ground support systems for space scientific experiments such as Shijian-8 satellite, Double Star and Shenzhou spacecrafts and the requirements of space scientific experiments in the future. This system platform supports status monitoring and control of space scientific experiments, telescience experiments and customizing standard data product. It can meet the need of multi-task in space scientific experiments with commonality and extensibility.
2013, 33(5): 518-524.   doi: 10.11728/cjss2013.05.518
Abstract(2027) [PDF 2583KB](1)
Abstract:
The ionospheric effect from solar activity can be seen as the background in the process of detecting the ionospheric precursor prior to strong earthquakes. The ionospheric variation induced by the forthcoming earthquake can be covered by the strong solar background during the period of high solar activity. The issue of how to remove the ionospheric effect from solar radiation is of outstanding significance. In this paper, a method of Empirical Mode Decomposition (EMD) is used to eliminate the solar background. As a case study, the global ionospheric map TEC before the M9.0 Tohoku earthquake on 11 March 2011 is analyzed. After the effect of solar radiation is removed using the EMD method, the precursor of the imminent earthquake is more obvious. The ionospheric anomaly had a local character and only appeared close to the earthquake epicenter while the useful signals were covered by the solar radiation background with traditional method, which implies that the EMD method is effective in eliminating solar radiation background.
2014, 34(1): 116-126.   doi: 10.11728/cjss2014.01.116
Abstract(759) [PDF 3915KB](1)
Abstract:
The technology of autonomous navigation is an inevitable trend in the development of spacecraft in the future. Based on the integrative platform of multi-sensors composed of sun sensor, moon sensor and the infrared Earth sensor, the observation model of multi-sensors were proposed. In order to construct the autonomous navigation system, the observability of navigation system was analyzed. Then the algorithm of astronomy autonomous navigation was built up based on two modes. One is based on the original astronomy multi-sensors data. The other is based on the analytical single position data calculated by the original astronomy multi-sensors data. Simulation results showed that the navigation precision of the mode based on original astronomy multi-sensors data was higher than that of the mode based on analytical single position data. And the navigation error was approximately within 200m when the observation data contains no system error. The precision of navigation with constant observation error is equal with that of the navigation with only random observation error when the system error estimation method is used.
2014, 34(2): 219-225.   doi: 10.11728/cjss2014.02.219
Abstract(2157) [PDF 2769KB](11)
Abstract:
Four kinds of scientific instruments are chosen as the payloads on Chinese Chang'E-3 Lander, including topography camera, lunar astronomical optical telescope, extreme ultraviolet imager and descending camera. Topography camera is to acquire the optical image of lunar surface topography around the landing area, and observe the rover moving process on the lunar surface. Lunar astronomical optical telescope operates in the near ultraviolet spectrum, which can observe the brightness variations of various stars. Extreme ultraviolet imager works on the wavelength of 30.4nm, and the observation target is the resonance scattering between Earth's plasma He+ layer and 30.4nm solar radiation. Descending camera is to acquire the lunar optical image in the landing region during descending. In this paper, Chang'E-3 Lander's scientific exploration missions, as well as the payloads' system design are introduced. Each payload's design and main technical specifications are also described in detail.
2007, 27(3): 182-191.   doi: 10.11728/cjss2007.03.182
Abstract(2615) [PDF 4375KB](0)
Abstract:
SSC is a result of the interrelation between strong solar wind dynamic pressure or interplanetary shock and the geomagnetosphere. Generally, the rise time of SSC varies from 4 minutes to 10 minutes. So, we refer to the SSC of the rise time which is more than 15 minutes as anomalous SSC event. We identified 5 anomalous SSC events from the geomagnetic index SYM-H data since the observation beginning of the geomagnetic field. Using the multipoint observations of the solar wind from the Wind, ACE, IMP 8, Goes and Geotail, the interplanetary causes of those anomalous SSC events were analyzed. It is found that： （1） all of 5 anomalous SSC events are accompanied with strong interplanetary disturbances, among which there are 4 events corresponding with the forward fast interplanetary shocks, and 3 events corresponding with multi-step solar wind dynamic pressure changes and 1 event corresponding with a sudden direction change and large amplitude variation in interplanetary electric field. （2） the rise time of those resulted from interplanetary shocks desponds on the orientation of the interplanetary shock, i.e., the bigger the angle between the interplanetary shock normal and the Sun-Earth line, the shorter the rise time, and the contribution of the orientation of the interplanetary shock is more remarkable than its speed. （3） There is no explicit relation between the rise time of the anomalous SSC events and the interplanetary field direction.
2013, 33(4): 353-373.   doi: 10.11728/cjss2013.04.353
Abstract(2751) [PDF 251KB](0)
Abstract:
Alfvén waves are found to be ubiquitous in the solar wind. Recent progress in observational studies of the waves is reviewed to formulate a microscopic picture for the Alfvénic fluctuations. The main aspects of the observational properties of these waves, including the wave intervals, propagation, evolution, origin and generation, are presented. Then Alfvén wave heating and acceleration of the solar wind plasma are briefly introduced. The relation of the waves to rotational and tangential discontinuities, magnetic decreases, and other relatively large-scale structures such as flux tubes/ropes, magnetic clouds and interplanetary coronal mass ejections in the solar wind is particularly investigated. Finally, some remaining open questions are also indicated due to their fundamental importance of understanding of the physical nature of Alfvén waves and the role of the waves in heating and accelerating the solar wind.
2014, 34(1): 46-52.   doi: 10.11728/cjss2014.01.046
Abstract(823) [PDF 3049KB](1)
Abstract:
The paper introduces the method of electron density inversion using COSMIC occultation data, and advantages of the inversion method are analyzed using practical calculation. Meanwhile, electron density profiles obtained from ISR (Incoherent Scattering Radar) are compared and analyzed with those from COSMIC occultation. Finally, electron density profiles over the SHAO (IGS station) which is located in Yangtze river region, are reversed using COSMIC occultation measurements during the total solar eclipse and the solar storm, and are compared with electron density profiles during the quite day. Ionospheric anomaly caused by the total solar eclipse and the solar storm are analyzed. The advantages of the inversion method from COSMIC occultation data have been found by using inversion method to monitor the ionosphere anomaly.
2014, 34(5): 544-546.   doi: 10.11728/cjss2014.05.544
Abstract(829) [PDF 3826KB](2)
Abstract:
The Hard X-ray Modulation Telescope (HXMT) is China's first astronomical satellite. It will perform a broad band (1-250keV) scan survey and do pointed observations of X-ray sources to study their spectra and multi-wavelength temporal properties. The pre-flight models of the satellites have been finished, and the flight models are in production. The expected launch date of HXMT is in late 2015.
2005, 25(6): 536-542.   doi: 10.11728/cjss2005.06.536
Abstract(2177) [PDF 2025KB](2)
Abstract:
On the basis of data from the geomagnetic network and ionospheric observatories in China, the geomagnetic low point displacement, diurnal variation anomalies of geomagnetic field and ionospheric f0F2 （critical frequency of F2 layer） anomaly phenomena before large earthquakes have been summarized. Anomaly distribution and characteristics of geomagnetic variation field and ionospheric f0F2 before Mani MS 7.5 earthquake on Nov.8, 1997, and Kunlunshan MS 8.1 earthquake on Nov. 14, 2001, have been comparatively studied. The result shows that the temporal spatial characteristics of short term and imminent anomalies of geomagnetic field and ionosphere are consistent. The obvious anomalies of diurnal variation of geomagnetic field near epicentral area and ionospheric f0F2 at Lhasa observation are found. The geomagnetic low point displacements appeared about one month before the two great earthquakes, the boundary lines of sudden change passed through the epicentral area.
2003, 23(2): 155-160.   doi: 10.11728/cjss2003.02.155
Abstract(2078) [PDF 1414KB](5)
Abstract:
2014, 34(1): 104-108.   doi: 10.11728/cjss2014.01.104
Abstract(859) [PDF 712KB](4)
Abstract:
Polar upflow ions from ionosphere to magnetosphere are crucial for space weather modeling. The origin and the acceleration of the upflow ions are the main scientific objectives for the Magnetosphere-Ionosphere-Thermosphere Coupling Constellation Mission. The constellation is composed of two magnetosphere satellites and two ionosphere/thermosphere satellites to monitor the polar region at different altitude jointly. The in-situ measurement on the source region of the upflow ions is vital for investigating the magnetosphere/ionosphere coupling, and it is also the requirement for designing orbit of the ionosphere/thermosphere satellite. We compared the circular and elliptical orbits based on the observations of other missions, and then choose the orbit of ionosphere/thermosphere satellites to be elliptical.
2014, 34(1): 38-45.   doi: 10.11728/cjss2014.01.038
Abstract(827) [PDF 7870KB](2)
Abstract:
Sporadic E (Es) is the irregular structure of ionosphere occurred in the layer E sporadically, and the highest electron density can exceed the background by more than 100 times. In East Asia, the Es is of frequent occurrence, and the Es morphological characteristics research in this region has the uniqueness and typicality, which is of great significance to explore the cause and reveal the essence of Es. Based on more than fifty years' data from Chinese ionospheric vertical sounders, and combining with the Japanese vertical sounders data, the strength characteristics, spatial distribution characteristics, daily variations, seasonal changes and long-term trends of the Es over East Asia were studied, and conclusions are obtained.
2014, 34(3): 249-261.   doi: 10.11728/cjss2014.03.249
Abstract(1067) [PDF 3248KB](2)
Abstract:
With a selected spot (45.1°-45.5°N, 33.1°-33.5° W) in Sinus Iridum, the measurements by Chang'E Lunar Microwave Sounder (CELMS) at five different lunar local time are analyzed. Then the lunar microwave brightness temperatures at four different frequencies of CELMS are simulated based on the microwave radiative transfer model. Grounded on the analyses for CELMS2 measurement as well as the simulated brightness temperatures in matched longitude, latitude and solar elevation angle, it is suggested that these two kinds of brightness temperature have a high correlation coefficient which can tend to 96%. Therefore, the stability of measurements of CELMS2 is verified.
2009, 29(1): 135-139.   doi: 10.11728/cjss2009.01.135
Abstract(3240) [PDF 605KB](2)
Abstract:
Image quality is the ultimate target for evaluating an optical remote sensing system. This paper introduces the concept and physical intension of resolution, and educes the concept of optical cutoff frequency and image smearing from the diffraction resolution of diffraction-limited incoherent imaging. To evaluate the image quality of sampling imaging system, the IQF (Image Quality Factor) λF/P is used to perform the sampling extension of CCD. This paper discusses the relation between optical remote sensor and SNR (signal to noise ratio) of the image. Taking advantage of image simulation function of ZEMAX software, the image of a space-based remote sensor with 9 m focal length and F number being 18 optical system is analyzed. The pixel size of the CCD is chosen to be 8.75μm and 13μm . The simulation result validates the influence of λF/P and SNR on image resolution. This result will instruct the choice of CCD optical remote sensor parameter.
2013, 33(5): 509-517.   doi: 10.11728/cjss2013.05.509
Abstract(2273) [PDF 2413KB](3)
Abstract:
NRLMSISE-00 model is widely used in orbit determination and prediction of low-Earth orbit satellites. In order to calibrate the atmospheric density of NRLMSISE-00, the density errors of the model were analyzed by comparing with the observations from GRACE and CHAMP satellites. The density of the model was generally larger than that observed by GRACE and CHAMP satellites, especially under low solar activity. The density of the model showed higher accuracy at high latitude and its error varied with latitude and longitude. At the same location on the same orbit, density error of the model varied with local time and reached its maximum at 02:00LT and 15:00LT while reached its minimum at about 10:00LT and 20:00LT relatively. The 10.7cm solar radio flux (F10.7 index) showed high correlation with the density errors. The density of the model showed low accuracy during the solar minimum while good accuracy during the solar maximum. The model density showed better result at CHAMP satellite orbit with lower altitude comparing to the GRACE orbit. The error has less correlation with ap index during relatively quiet period of geomagnetic field (ap< 27).
2005, 25(1): 57-62.   doi: 10.11728/cjss2005.01.057
Abstract(1916) [PDF 1709KB](1)
Abstract:
2014, 34(3): 287-295.   doi: 10.11728/cjss2014.03.287
Abstract(828) [PDF 615KB](2)
Abstract:
A theoretical model of ionospheric electric fields at mid- and low-latitudes is developed. In the geomagnetic dipolar coordinate system, the ionospheric dynamo equations were solved, and the ionospheric electric potential and electric field were derived respectively. Major parameters for the model inputs, such as the neutral winds, the densities and temperatures of electron, ions and neutrals, are obtained from empirical models. The global ionospheric electrical potential and field at mid- and low-latitudes derived from our model are largely in agreement with the results presented by other authors and the empirical model. Using our model, it is found that the diurnal component of the HWM93 wind mainly contributed to the formation of the vertical electric field, while the semidiurnal component mainly contributed to the zonal electric field. Finally, by adjustment of the input F region winds and conductivities, most discrepancies between our model and the empirical one can be eliminated, and it is proved that the F region dynamo is the most significant contribution to the electric fields.
2009, 29(2): 161-165.   doi: 10.11728/cjss2009.02.161
Abstract(4583) [PDF 567KB](2)
Abstract:
In this paper, the solar wind electrons which are moving toward the moon surface are traced to study the reflection of these electrons due to the crustal magnetic field of the moon. The magnetic field in the solar wind Bsw is supposed to be perpendicular with the moon surface, and the crustal magnetic field is supposed as a small dipole field with a moment Mcb, where Mcb are parallel, anti-parallel, and ±90° correspond to the direction of the Bsw. The calculation shows that the reflection number of the electrons varied with the angle between Mcb and Bsw. When Mcb is parallel with Bsw, the number of the reflected particles is the largest. The number decreases when the angle between Mcb and Bsw increases. These results are expected to provide some important information for the remote measuring of the lunar crustal magnetic field by using electron reflectometry technique.
2012, 32(5): 665-680.   doi: 10.11728/cjss2012.05.665
Abstract(2143) [PDF 590KB](4)
Abstract:
The ionosphere varies over multiple time scales, which are classified into two categories: the climatology and weather variations. In this national report, we give a brief summary of recent progresses in ionospheric climatology with focus on (1) the seasonal variations, (2) solar cycle effects, and (3) empirical modeling of the ionosphere. The seasonal variations of the ionosphere have been explored in many works to give a more detailed picture with regional and global features at various altitudes by analyzing the observation data from various sources and models. Moreover, a series of studies reported the response of the ionosphere to solar cycle variations, which revealed some novel and detailed features of solar activity dependence of ionospheric parameters at different altitudes. These investigations have improved our understanding on the states of the ionosphere and underlying fundamental processes, provided clues to future studies on ionospheric weather, and guided ionospheric modeling, forecasting and related applications.
2012, 32(5): 681-692.   doi: 10.11728/cjss2012.05.681
Abstract(2232) [PDF 155KB](7)
Abstract:
This article summarizes the researches on the middle and upper atmosphere by Chinese scientists in 2010?2012. The focuses are placed on the advances in construction of ground-based remote sensing facilities, the mean state and long-term changes in the middle atmosphere circulation, the prevailing dynamical processes, and the coupling of the middle atmospheric layers.
2009, 29(1): 68-72.   doi: 10.11728/cjss2009.01.068
Abstract(3013) [PDF 566KB](4)
Abstract:
Aerospace Relay Mirror System (ARMS) as a new conceptional weapon used in reflection of High Energy Laser (HEL) in space is studied. It extends the attacking range of Ground Based Laser (GBL) weapons enormously. Relevant researches have been carried out for many years. The structure and operating theory of the entire system consists of ground-based high energy laser weapon and space-based relay mirror. The main work of this study was focused on the analysis of relay mirror energy character to deduce the relationship among the attacking range of weapon and diameter of ARMS and target irradiance. Calculation examples are also given. The result further proves the strong points and feasibility of ARMS in principles. It is summarized that more importance should be attached to ARMS development. The results given in this paper can be the reference of actual ARMS system to some extends.
2014, 34(1): 1-10.   doi: 10.11728/cjss2014.01.001
Abstract(1254) [PDF 7054KB](0)
Abstract:
The wavelet analysis method was used to discuss the 27-day periodicities characteristic of the solar wind speed detected by ACE and STEREO-B satellites from the year of 2008 to 2011. Using the method of unary linear regression, the linear equation of solar wind speed is calculated. From the analysis and calculation results detected by ACE and STEREO-B, it is shown that the solar wind speed in 8～16d and 16～32d frequency domain is significant. The solar wind speed detected by the two satellites presents significant 27-day periodicities in parts of the same frequency domain. And it presents better correlation in the year when solar activity is low. As an application example, solar wind data detected by STEREO-B is applied to predict the solar wind speed of ACE from 1 to 17 in October, 2012. The results show that the trend of predicted values and measured values are consistent, although the CME has a certain influence on the predicted values. Through this research, the relationship of solar wind speed detected by ACE and STEREO-B satellites was preliminarily studied, and the solar wind speed was detected by STEREO-B a few days before it came to the Earth. This work laid the foundation to establish the medium-term forecast models for the non-recurrent geomagnetic storms.
2009, 29(2): 183-187.   doi: 10.11728/cjss2009.02.183
Abstract(4863) [PDF 596KB](3)
Abstract:
Dual-frequency GPS receiver can automatically correct time delay error caused by ionospheric Total Electron Content (TEC). But it cannot eliminate signal scintillation error caused by ionospheric irregularities. Even for differential GPS systems, ionospheric error is one of major sources in GPS positioning, for example, error from ionospheric TEC gradient, which will affect accuracy and degrade performance of GPS application system. In this paper, the magnitude of ionospheric TEC horizontal gradient is studied by means of GPS observations. The vertical TEC, and its horizontal gradient and ROTI index over NTUS station, which located in equatorial anomaly region, are derived from GPS observation provided by IGS network. It is found that, between post-sunset and around midnight, the ionospheric TEC has great fluctuation, and intense radio waves scintillation, which is represented by big ROTI index, takes place during this periods. Furthermore, the steep TEC horizontal gradient and its fast variation with respect to time appear. By comparison, the ROTI index, ionospheric TEC horizontal gradient and vertical TEC correlate very well with each other, and their variations characteristics result from density irregularities produced by plasma instability in ionosphere. It is suggested that when scintillation events are investigated, ionospheric TEC gradient is also one of considerable parameters.
2014, 34(2): 168-179.   doi: 10.11728/cjss2014.02.168
Abstract(1287) [PDF 1085KB](3)
Abstract:
The ground-based GPS receivers and hence networks enable studies of the ionosphere on a large regional or global scale by measuring the ionospheric TEC from dual-frequency GPS observations. However, originated in the hardware delay of the GPS satellite and receivers, a systematic bias affects the accuracy of the TEC derivation greatly. For accurate estimation of TEC, satellite and receiver instrumental biases should be removed from TEC measurements properly. This paper gives a comprehensive review of the algorithms on TEC and GPS hardware delays derivations. Starting from ionospheric radio wave propagation, the paper describes how the TEC is related with hardware delays. Then the TEC derivation methods are analyzed, evaluated and categorized into 3 main types. Finally, some suggestions are provided for further research on derivation of TEC and hardware delay.
2007, 27(6): 505-511.   doi: 10.11728/cjss2007.06.505
Abstract(2182) [PDF 1912KB](4)
Abstract:
Geomagnetism Aided Navigation （GAN） is a new branch of the integrated navigation technique. Navigation principle and the development of the GAN system are introduced in the paper. The emphasis is laid on the research of the matching method. Geomagnetic matching is the technique that uses a geomagnetic map to determine the location of the vehicle. The obtained position information can be used to limit error accumulation of the Inertial Navigation System （INS）. An improved correlation matching method based on the contour constraint is proposed. Map contour is used to confine the searching process, changing the uncertainty field to an uncertainty line, which efficiently reduces the computation burden of the system and eliminates the initial position error of INS. A nearest point principle （NPP） is applied in the precision matching part. The NPP technique can bind the error of INS accumulated during the matching process. The simulation results show that the proposed method can greatly improve the efficiency and precision of the whole GAN system. The accuracy of the matching method is less than the unit cell size of the map. In addition, the proposed method is, to some extend, adaptive to the heading error of the INS.
2014, 34(6): 822-829.   doi: 10.11728/cjss2014.06.822
Abstract(1152) [PDF 3347KB](2)
Abstract:
In this paper, the ionospheric perturbations in three parameters have been analyzed around Yushu earthquake, including f0F2 from ionosonde, GPS TEC, and in-situ plasma parameters by satellite. Their temporal and spatial relationship with this event were studied, and the results showed synchronous disturbances in multi-parameters on 13 April, just one day before the Yushu earthquake. The f0F2 abnormally increased 40% relative to its sliding median of 5 days before, and its anomalous center moved from southeast to southwest. GPS TEC with abnormal amplitude of 15TECU (1TECU=1016m-2) concentrated in a longitudinal scale of 15° over the south of the epicenter, and similar anomalies were found at its conjugate areas. While the in-situ observation of oxygen ion density Ni(O+) from DEMETER reached its maximum on April 13 for the four months from January to April in 2010, with the anomalies deviating to the equatorial areas but limited in the longitude scale of 30°-50°. Su mming up the anomalous characteristics in these three parameters, whatever the local feature in space, or the close relevance in time, both exhibited possible relationship with the Yushu earthquake. Combined with other observations, the seismo-ionospheric coupling mechanism was discussed during the preparation process of Yushu earthquake.
2014, 34(5): 747-756.   doi: 10.11728/cjss2014.05.747
Abstract(811) [PDF 148KB](0)
Abstract:
In the past two years, space life science research in China is characterized by a wide area of basic researches for providing foundation for the future China Space Station. The effect of microgravity and radiation was further studied from physiology phenomena to the level of bio-molecule mechanisms. Chinese space life science is maturing in a new era of comprehensive development. Here, we review and summarize researches on space life sciences which were contributed by Chinese scientists.
2009, 29(2): 249-256.   doi: 10.11728/cjss2009.02.249
Abstract(2965) [PDF 378KB](1)
Abstract:
The article presents a structural analysis of a new space probe-solar sail. It was deployed successfully on ground. The loads for an outer space mission was introduced and expressed with equation. As a special state, the largest load around earth was used to analyze the model by the finite element method. Some results about strain and stress was obtained after setting some initial parameters. Compared to the results in the literature, the results presented here are significant.
2014, 34(1): 63-72.   doi: 10.11728/cjss2014.01.063
Abstract(1127) [PDF 1570KB](0)
Abstract:
Currently, GNSS (Global Navigation Satellite System) is widely used in ionospheric TEC monitoring. The traditional method of GNSS monitoring ionospheric TEC is based on the original output measurements of navigation receiver, and then we obtain the ionospheric TEC information through the data conversion. The signal processing algorithm is also the navigation receiver algorithm which is used for navigating. The purpose of this work is to design a new GNSS dual-frequency signals tracking algorithm for the GNSS ionospheric TEC monitoring application, which is called sum-diff joint tracking algorithm. Compared with the traditional method, the algorithm is directly tracking the ionospheric TEC changes, and can improve the sensitivity of dual-frequency tracking and the TEC observation precision, so that it can improve the performance of GNSS monitoring ionospheric TEC.
2010, 30(4): 321-332.   doi: 10.11728/cjss2010.04.321
Abstract(2277) [PDF 321KB](1)
Abstract:
This paper presents a brief summary of our recent work based on global MHD simulations of the Solar wind-Magnetosphere-Ionosphere (SMI) system with emphasis on the electrodynamic coupling in the system. The main conclusions obtained are summarized as follows. (1) As a main dynamo of the SMI system, the bow shock contributes to both region 1 Field-Aligned Current (FAC) and cross-tail current. Under strong interplanetary driving conditions and moderate Alfven Mach numbers, the bow shock's contribution may exceed more than fifty percent of the total of either region 1 or cross-tail currents. (2) In terms of more than 100 simulation runs with due southward Interplanetary Magnetic Field (IMF), we have found a combined parameter f = EswPswMA-1/2 (Esw, Psw, and MA are the solar wind electric field, ram pressure, and Alfven Mach number, respectively): both the ionospheric transpolar potential and the magnetopause reconnection voltage vary linearly with f for small f, but saturate for large f. (3) The reconnection voltage is approximately fitted by sin3/2θIMF/2, where θIMF is the IMF clock angle. The ionospheric transpolar potential, the voltage along the polar cap boundary, and the electric fields along the merging line however defined they may be, respond differently to θIMF, so it is not justified to take them as substitutes for the reconnection voltage.
1989, 9(3): 175-179.   doi: 10.11728/cjss1989.03.175
Abstract(1475) [PDF 359KB](3)
Abstract:
This paper presents a model describing the changes of ion charges and their relaxation process in solar flare phenomena based on the fact of low temperature magnetic loops emerging before solar flare bursts and prompt heation of plasma in impulsive phase of solar flares. Numerical calculations of charge state distributions and mean ionic charges of element C, N, Oare obtained and the results are coincident with the observations.
1998, 18(2): 161-167.   doi: 10.11728/cjss1998.02.161
Abstract(1637) [PDF 289KB](4)
Abstract:
In this paper, the problem of orbital design of vertical hitting moon probe is discussed. The probe starts from a near-earth circular parking orbit and accelerates in the velocity direction of the parking orbit then enters the landing moon orbit and finally hits the moon with free flight, Firstly,in the constraint conditions of the parking orbit,energy limit,and the landing moon point using theories of two-body and double two-boby, not only the approximate initial values of the orbit are given,but also the characteristics of it are illustrated. Then, based on a dynamic model of general restricted four-boby, three point boundary values are searched and the high accuracy orbit of the probe is gained.
2009, 29(3): 338-345.   doi: 10.11728/cjss2009.03.338
Abstract(4219) [PDF 761KB](0)
Abstract:
In this paper, when the case of the attitude of base controlled and its location uncontrolled, we discuss the control for free-floating space manipulator to track desired trajectory in joint space. Combined the relationship of the linear conversation of the system and the Lagrange approach, the full-controlled dynamic equation of free-floating space manipulator are established. Base on above results proposed, aiming at the case of free-floating space manipulator system with uncertain payload parameters, a composite scheme of a computed torque controller plus a fuzzy compensator is proposed to track desired trajectories in joint space. Namely, it will transfer the impact of system's unknown parameters to computed torque controller through fuzzy adaptive compensation system controller, to
ensure the whole closed-loop control system's asymptotic stability with the existence of unknown parameters. The mentioned control scheme can effectively control two joint of space manipulator to stably track the desired trajectory in joint space. It has obvious advantages that with needless feedback and measured the position, velocity, acceleration, attitude angle velocity and attitude angle acceleration of the floating base. At the same time, no requirements for the dynamic equations of the system are linearly dependent on inertial parameters. A two space-based manipulator system is simulated to verify the proposed control scheme.
2014, 34(5): 563-564.   doi: 10.11728/cjss2014.05.563
Abstract(1025) [PDF 67KB](1)
Abstract:
The main activities of Chinese space solar physics in 2012-2014 include: to continue studying the mid and long-term (2016-2030) plan of Chinese space solar physics; to arrange a group of pre-study projects of space solar physics; to initiate and continue a few solar mission-level projects. This paper summarizes all these activities briefly.
2008, 28(5): 395-401.   doi: 10.11728/cjss2008.05.395
Abstract(2402) [PDF 297KB](7)
Abstract:
This paper gives a brief introduction of YingHuo-1 (YH-1), a Chinese Martian Space Environment Exploration Orbiter. YH-1 is a micro-satellite developed by Chinese Aerospace Industry,and will be launched together with Russian spacecraft, Phobos-Grunt, to orbit Mars in September,2009. Four payloads are selected for the mission, plasma package, including of electron analyzer, ion energy and mass analyzer; sat-sat occultation receiver; flux-gate magnetometer; and optical monitor.YH-1 mission focus on the investigation of the characteristics and its evolution of the Martian space Environment, and identifying major plasma processes, which provide channels for Martian volatiles escaping.
2015, 35(5): 647-652.   doi: 10.11728/cjss2015.05.647
Abstract(770) [PDF 2765KB](0)
Abstract:
To simulate the different lunar phases and ensure continuous adjustability of the radiant brightness, a new broad spectrum light and frosted glass were applied and designed in the optical system for lunar simulator with the shapes and radiance being able to be adjusted. According to the engineering demand and index requirements of the optical system, three major design aspects are addressed, including the high reliability and maintainability for broad-spectrum light, heat dissipation in lunar simulator for long working hours, and bearing of the main frame under different working conditions. By designing a reasonable machine structure, and through the structure itself with the matrix arrangement of 48 axial flow fans, an effectively cooling air duct is established. Deformation and temperature were calculated by the finite element software ANSYS. The results showed that the displacement deformation reached 0.33mm and stress deformation reached 0.02MPa at the temperature of 20℃; when the main frame was in the temperature field between 20℃ and 65℃, the maximum displacement deformation reached 13.30mm and maximum stress deformation is 97.90MPa, and the amount of this deformation is very small in considering of the mechanical structure dimensions and weight of the lunar simulator.
2014, 34(2): 235-241.   doi: 10.11728/cjss2014.02.235
Abstract(1358) [PDF 838KB](7)
Abstract:
High precision measurement of the magnetic field is required for in-orbit magnetic field monitoring and mapping. Due to the restrictions of processing technology and installation, the three axes of fluxgate magnetometer cannot be strictly orthogonal and the offsets in three directions are unknown in actual measurement. To solve this problem, it is necessary to determine the alignment and offset of the fluxgate magnetometer in-orbit instead of on the ground. According to the method of calibrating with scalar magnetometer, a method for calibrating the alignment, sensitivity, and offset by an improved least square calibration algorithm is proposed. Results show that considering the noise of detector itself, the error of fluxgate magnetometer can be reduced from about 100nT to less than 0.2nT. This calibration algorithm offers a feasible way of in-orbit high-precision measurements.
2014, 34(1): 73-80.   doi: 10.11728/cjss2014.01.073
Abstract(1022) [PDF 3616KB](0)
Abstract:
The periodic characteristics of solar F10.7 index and the thermospheric density at 250km, 400km and 550km altitude have been investigated. The results show that the thermospheric density correlates well with the solar activities, and both of them have significant period of 27 days and 11 years. Besides, the thermospheric density also has 7～11 days' period, semiannual and annual variations. The response of thermospheric density lags the solar activity for three days. No matter what the level of geomagnetic activity is, the correlation between solar activity and thermospheric density at 400km is larger than 250km, minimum at 550km. The relationships between the neutral density and solar activity show linear, saturation and amplification features. The thermospheric density in higher altitude is more sensitive to the solar activities.
2009, 29(1): 34-38.   doi: 10.11728/cjss2009.01.034
Abstract(3853) [PDF 539KB](1)
Abstract:
Three-DOF air-bearing test-platform is the key test base of simulating the satellite attitude motion for simulating the satellite emulation effective, so as to simulate the torque-free environment in the space. 3-DOF air-bearing test-platform disturber moment is analysed. When there is a shift between the gravity center and the rotary center, the static unbalance appears. While a shift exits between main inertia axes and rotary axis, the dynamic unbalance appears. In addition, the principal and procedure of balancing a 3-DOF air-bearing test-platform and the technology of manual and automatic balancing it are discussed. The equations of kinetics are derived. At last a lot of methods are used to measure the static unbalance moment and disturber moment in order to supply satellites' attitude motion with a model of availability, precisions and efficiency.
2014, 34(5): 688-702.   doi: 10.11728/cjss2014.05.688
Abstract(955) [PDF 7634KB](4)
Abstract:
In this report, we summarize the needs of space weather models, and recommend that developing operational prediction models, rather than transitioning from research to operation, is a more feasible and critical way for space weather services in the near future. Operational models for solar wind speed, geomagnetic indices, magnetopause, plasma sheet energetic electrons, inner boundary of ion plasma sheet, energetic electrons in outer radiation belt, and thermospheric density at low Earth orbit, have been developed and will be introduced briefly here. Their applications made a big progress in space weather services during the past two years in China.
2016, 36(2): 117-138.   doi: 10.11728/cjss2016.02.117
Abstract(1774) [PDF 11002KB](7)
Abstract:
Time-domain astrophysics will enter a golden era towards the end of this decade with the advent of major facilities across the electromagnetic spectrum and in the multi-messenger realms of gravitational wave and neutrino. In the soft X-ray regime, the novel micro-pore lobster-eye optics provides a promising technology to realise, for the first time, focusing X-ray optics for wide-angle monitors to achieve a good combination of sensitivity and wide field of view. In this context Einstein Probe, a soft X-ray all-sky monitor mission, was proposed and selected as a candidate mission of priority in the space science programme of the Chinese Academy of Sciences. This paper reviews the most important science developments and key questions in this field towards 2020 and beyond, and how to achieve them technologically. It also introduces the Einstein Probe mission, including its key science goals and mission definition, as well as some of the key technological issues.
2000, 20(1): 32-39.   doi: 10.11728/cjss2000.01.032
Abstract(1505) [PDF 632KB](2)
Abstract:
Methods of single frequency carrier phase-based relative orbit determination(OD) and kinematic network OD for low-earth satellite are developed. From theresults calculated using L1 data collected by GPS/DR onboard Topex/Poseidon,we can draw following conclusions: (a) the accuracy of single frequency carrierphase-based relative OD may attain the order of a few decimeters; (b) the accuracyof relative OD depends on the data quality of ground tracking stations; (c) theaccuracy of kinematic network OD is equavalent to a weighting among relative ODsof different ground tracking stations and can improve the reliability and precisionof OD due to its redundant condition and good geometric configuration.
2000, 20(2): 97-102.   doi: 10.11728/cjss2000.02.097
Abstract(1727) [PDF 559KB](2)
Abstract:
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.
2013, 33(2): 200-206.   doi: 10.11728/cjss2013.02.200
Abstract(2106) [PDF 632KB](4)
Abstract:
The technical scheme of a dynamic star simulator based on the LCOS optical splicing technology is proposed in order to meet the demands of a star sensor in spacecraft engineering. Optical system parameters of the simulator are calculated by the specification of a LCOS. The two LCOS optical splicing principle and scheme are introduced in detail, method of the dynamic star map realization is given, and its error is analyzed. The simulating results indicate that field of view is of 10.2° × 10.2°, star magnitude simulated is of 2～6.5, the single star field angle is less than 20", and the star diagonal distance error is less than 22". The experimental result can satisfy the system requirements of big field of view, wide magnitude range and update rate, etc.
2009, 29(1): 29-33.   doi: 10.11728/cjss2009.01.029
Abstract(4258) [PDF 508KB](4)
Abstract:
The attitude control problem of certain microsatellites with uncertainty structure and unknown but constant external interference is studied in this paper. Based on Lyapunov method and utilizing the input-output property of Euler-Lagrange systems, a robust adaptive controller without dynamics decoupling is presented. Computer simulation shows that this control algorithm possesses good control performance and robustness.
2015, 35(2): 166-177.   doi: 10.11728/cjss2015.02.166
Abstract(1024) [PDF 4011KB](2)
Abstract:
Monthly mean values of f0F2 parameter, with an hour time interval resolution for diurnal variation, obtained at Guangzhou (23.2°N, 113.3°E) station are used to investigate the variations and comparisons with the International Reference Ionosphere (IRI-2012) model predictions. The results show that generally, IRI-2012 predictions follow well with the diurnal and seasonal variation patterns of the observed values of f0F2, and the predictions with CCIR coefficients is better than URSI. However, there are systematic deviation between observed values and IRI predictions with either CCIR or URSI coefficients. Generally IRI model greatly underestimates the values of f0F2 from about noon to sunrise of the next day, especially at 20:00LT, and slightly overestimates them from sunrise to about noon. The deviation will increase at the time when the nighttime enhancement occurred, especially in spring and autumn. This means that the predictions can not follow well with variation of the observed values of f0F2.
2012, 32(5): 605-617.   doi: 10.11728/cjss2012.05.605
Abstract(2333) [PDF 159KB](1)
Abstract:
In the first part of this paper, we describe briefly the mid and long-term plan of Chinese space astronomy, its preliminary study program, the current status of satellite missions undertaken, and the current status of astronomy experiments in China’s manned space flight program. In the second part, the recent research progress made in the fields of solar physics is summarized briefly, including solar vector magnetic field, solar flares, CME and filaments, solar radio and nonthermal processes, EUV waves, MHD waves and coronal waves, solar model and helioseismology, solar wind and behavior of solar cycle.
2013, 33(4): 458-464.   doi: 10.11728/cjss2013.04.458
Abstract(2195) [PDF 619KB](3)
Abstract:
Based on the linear dynamics model and nonlinear dynamics model, the sun-centred displaced orbits keeping control problem is studied. Firstly, the solar sail dynamics model in cylindrical coordinate form is derived and orbit controllability of the state equation by linearizing the model along the nominal orbit is investigated. Then, by choosing the control weighted matrix R reasonably, a control law for the linear model is designed using the Linear-Quadratic Regulation (LQR) approach. The numerical simulations which are obtained by taking the control law into the nonlinear model indicate that the designed controller which has asymptotic stability and high control accuracy is capable.
2018, 38(5): 598-603.   doi: 10.11728/cjss2018.05.598
Abstract(712) [PDF 2297KB](2)
Abstract:
Through the implementation of China's Lunar Exploration Program (CLEP), a large amount of data has been acquired. This paper will present the latest scientific results based on these data involving the composition, topography, space environment, subsurface structure of the Moon, and asteroid exploration and moon-based observations, etc.
2009, 29(1): 10-16.   doi: 10.11728/cjss2009.01.010
Abstract(3949) [PDF 800KB](1)
Abstract:
A combinatorial method was used to deposit a Zn-Al material library on a low carbon steel substrate by ion beam sputtering. As-deposited film samples were annealed at varied heat treatment conditions to promote the diffusion between the elements for a through-thickness homogenous sample. XRD and EDS analyses were carried out for composition and structure, AFM and TEM images were obtained for morphology observation. Nanoindentation tests were conducted to investigate the mechanical behaviour of samples. Electrochemical corrosion properties of the Zn-Al material library were evaluated by a modified tape test. A relationship among composition-structural phase-property of Zn-Al alloy films was set up by the fast screening method. Results show that the Zn-Al film with a composition of about 30 at % Zn has either the best anti-corrosion property, or better mechanical property.
2009, 29(5): 449-455.   doi: 10.11728/cjss2009.05.449
Abstract(2848) [PDF 688KB](3)
Abstract:
Mars has been one of the most interesting planets in the solar system for human beings due to its orbit characteristics and its geology, and the main attraction is the possibility to find life on it. Since the 1990s, many exploration missions have been sent to Mars. From the beginning of this century, many space power countries have announced their manned Mars program strategy. China was the fifth country in the world to launch its artificial satellite on its own, and the third country to have the ability to carry out independent manned space program. However, China is not a power at all in deep space exploration. To catch up, China and Russia have signed an agreement on a joint Mars exploration program by sending a Chinese microsatellite Yinghuo-1 (YH-1) with Russian's Phobos-Grunt mission. Once YH-1 is in orbit, it will not only carry out its own exploration mission but also conduct joint measurement with Russian Phobos-Grunt spacecraft. In this paper, the scientific background is reviewed, the scientific objectives of YH-1 are given, and the scientific payloads and operation considerations are also briefly described.
2008, 28(5): 361-369.   doi: 10.11728/cjss2008.05.361
Abstract(2223) [PDF 3447KB](4)
Abstract:
Chang'E-1 lunar Orbiter was launched by Long March 3A rocket from Xichang Satellite Launch Center at 18:05 BT (Beijing Time) Oct. 24, 2007. It is the first step of its ambitious three-stage moon program, a new milestone in the Chinese space exploration history. The primary science objectives of Chang'E-1 lunar orbiter are to obtain three-Dimension (3D) stereo images of the lunar surface, to analyze the distribution and abundance of elements on the surface, to investigate the thickness of lunar soil, evaluate helium-3 resources and other characteristics, and to detect the space environment around the moon. To achieve the above four mission objectives, eight sets of scientific instruments are chosen as the payloads of the lunar orbiter, including a CCD stereo camera (CCD), a Sagnac-based interferometer spectrometer (IIM), a Laser Altimeter (LAM), a Microwave Radiometer (MRM), a Gamma-Ray Spectrometer (GRS), an X-ray spectrometer (XRS), a High-Energy Particle Detector (HPD), and two Solar Wind Ion Detectors (SWID). The detected data of the payloads show that all payloads work well. This paper introduces the status of payloads in the first phase and preliminary scientific results.
2013, 33(6): 608-616.   doi: 10.11728/cjss2013.06.608
Abstract(890) [PDF 3183KB](0)
Abstract:
The characters of the Pc3-4 magnetic pulsations and their relationships to interplanetary conditions were studies during the periods of both the magnetic quite (March 20 to 27, 2011) and storm (September 25 to October 1, 2011), using ground-based geomagnetic field measurements from the new-developed Chinese Meridian Project. Preliminary results show there exist significant dawn-dusk asymmetric distribution of the Pc3-4 pulsations in the middle-low latitudes (1.3<L < 2.3), with Pc3-4 pulsations activity are observed mainly in the pre-noon sector, during both time periods. They are closely related to the interplanetary conditions, with high-speed solar wind and solar wind dynamic pressure pulsation leading to enhancement of the Pc3-4. However, Pc3-4 pulsations activity is not observed near the equatorial low latitudes (L <1.3) due to latitudinal effect.
1999, 19(2): 160-166.   doi: 10.11728/cjss1999.02.160
Abstract(1758) [PDF 464KB](1)
Abstract:
Fault diagnostic system is of great importance in monitoring and controllingspacecraft in the ground control center. The bottleneck problem of knowledge acquisition for spacecraft fault diagnosis is solved by using fault tree knowledge. Thepaper presents a fault diagnostic method based on fault tree and neural networkmodel. Based on the hierarchical model of fault tree, knowledge representationmethod based on frame and generalized rule is presented, and the relevant certainand possible reasoning strategies are described. Learning diagnosis based on neuralnetwork model is used to confirm and verify the results from the possible reasoning. By using Borland C++ under Windows, a fault diagnostic prototype systemis developed, and the validity is also demonstrated by diagnosing a satellite powersystem fault imitation bench.
2016, 36(3): 366-372.   doi: 10.11728/cjss2016.03.366
Abstract(732) [PDF 1383KB](2)
Abstract:
Induction magnetometer,based on Faraday's law,is used to measure the magnetic field changes with low frequency in space.It usually has the function of on-orbit FFT spectrum analysis, which can obtain the information of magnetic field fluctuation directly,such as frequency and amplitude.However,when using FFT to process the truncated signal,non-complete period sampling will cause spectrum leakage and fence effect.Namely the spectrum information will generate deviations, which affects the accuracy of real-time monitoring of magnetic field changes.Compared with traditional FFT,the all-phase FFT with phase invariability can effectively prevent spectrum leakage.In this paper,an all-phase time-shift phase difference method (apFFT/apFFT) is used to correct the aveform data of a satellite induction magnetometer.Simulation and experimental results indicate that this method can improve the measurement accuracy.This study also provides a method about on-orbit spectrum analysis for the next generation of spaceborne induction magnetometer.
2010, 30(6): 612-619.   doi: 10.11728/cjss2010.06.612
Abstract(2356) [PDF 760KB](6)
Abstract:
In extreme environment of the space, most of Extra-Vehicular Activity (EVA) has to depend on the aid of robotic manipulator. As a main part of International Space Station (ISS), robotic manipulator is playing a crucial role in the on-orbit assembly, external maintenance and the operations of ISS, and it therefore allays the working time and frequency of astronauts EVA. This paper reviews the development of the robotic manipulator based on ISS member countries' research, including shuttle remote manipulator, space station remote manipulator, European robotic arm, Japanese experiment module remote manipulator and German manipulator. It is expected that the concerning research will provide some references for the design of Chinese robotic manipulator.
2017, 37(3): 270-276.   doi: 10.11728/cjss2017.03.270
Abstract(813) [PDF 4240KB](0)
Abstract:
A Spectral Whitening Method (SWM) is introduced and applied in the study of ionospheric weather disturbances to calculate Js, Jr and Jp indices on the basis of Total Electron Content (TEC) data provided by IGS. These indices can reflect the disturbances of ionospheric weather of single station, latitude circle (integral along longitude) and the whole planet separately. During a geomagnetic storm in March 2015, all three indices well reflect the ionospheric disturbances. The correlation coefficient between Jp and Dst indices reaches -0.72, and the 2D images of ionospheric disturbances can be well captured by Js map. The correlation coefficient between Jp index and Dst index, from 2011 to 2014, reaches -0.67 if Jp is greater than or equal to 2, and the correlation coefficient can reach -0.87 if Jp is greater than or equal to 3. By analyzing the frequencies of different levels of geomagnetic storms under different threshold values of Jp index, the results suggest that Jp index, as a possible characterization parameter of ionospheric weather condition, can well reflect planetary ionospheric disturbances during geomagnetic storms.
2015, 35(5): 525-532.   doi: 10.11728/cjss2015.05.525
Abstract(613) [PDF 5427KB](4)
Abstract:
With a homogeneous model of the Moon, the induced magnetic field caused by step-transient disturbation of interplanetary magnetic field is simulated by the electromagnetic induction theory. As the range of conductivity assigned, the variation from step to calm of both the vectors and magnitudes can be obtained with a fixed permeability μ0. Then the magnetic characteristic transient response function, the field components and total field at 3 different points selected in a longitude line can all be given in different conductivities by numerical inverse Laplace transformation. The calculation provides a reasonable result that components perpendicular to the external step-transient field will disappear in a long-enough time, whereas the parallel component will become unity with it. When the external field step varies, the maximum field value which can be detected in the vicinity of the equator and the polar region are 13.65nT and 2.71nT, respectively. The processes of parallel component change are remarkably different in low latitude and polar region. This phenomenon reflects that magnetometers in different sites of lunar surface may lead to different field curves.
2005, 25(2): 154-160.   doi: 10.11728/cjss2005.02.154
Abstract(1709) [PDF 2577KB](2)
Abstract:
2014, 34(4): 449-459.   doi: 10.11728/cjss2014.04.449
Abstract(897) [PDF 5017KB](3)
Abstract:
Two Line Elements (TLE) is the only publicly available and most complete data sets of Earth orbit objects. The prediction accuracy with SGP4/SDP4 is limited. The TLE+SGP4/SDP4 prediction error sources and improvement method with historical TLE data were analyzed. A pseudo-observation data generation method was introduced. The fitting period of TLE data and the value of Δt used in generating pseudo-observation are dependent on the orbital altitude. An effective area-to-mass ratio (A/M) determination method was obtained. GPS satellites prediction error in case of η estimated or not are also tested. The improved prediction accuracy is prominent in the application of US and Russian satellites collide event. Objects were selected and their orbit were predicted with an improved TLE-numerical method. The statistical results show that the TLE prediction accuracy is greatly improved. The application of the improved TLE and possible problems were also discussed.
2007, 27(4): 279-285.   doi: 10.11728/cjss2007.04.279
Abstract(2508) [PDF 2246KB](3)
Abstract:
In this paper the Kriging method was introduced to map Central and Northern China （30°N-55°N, 70°E-140°E） Total Electron Content （TEC） Map （CNC TEC Map）. Firstly, three popular ionosphere models （Klobuchar model, IRI and JPL GIM） were compared with grid TEC. Then CNC TEC Map using Kriging method with constant drift, linear drift and quadratic drift were compared with each other. Then TEC map derived from nearest neighbor method, polynomial regression method （order=5） and Kriging method with different temporal resolution of 5 minutes, 30 minutes and 120 minutes were compared. The result revealed that even in the mid-latitude area, these popular ionosphere models showed great differences from observation; that the results of the Kriging algorithms were similar which led us go use ordinary Kriging method, i.e. Kriging method with constant drift; and that the Kriging method was begger than other methods, especially when temporal resolution was high.
2009, 29(1): 154-158.   doi: 10.11728/cjss2009.01.154
Abstract(3091) [PDF 693KB](0)
Abstract:
It is summarized in the paper that material science processing experiment furnaces on International Space Station (ISS) prepared by some country. Some features are presented as follows: highly integrated synthesis experiment ability such as preparing materials, measuring, analyzing and managing, higher precision, stability and long lifetime; modularization, standardization and assembled, applying telescience experiment technology. Since 1998, to meet the requirement for China space station in the future, a few kinds of telescience processing furnaces in space and teleoperation prototype furnaces have being developed, which can be used during unmanned long flight and with robotic sample replacement. Proposal is given for design and development aiming at that the function is specialized, the structure is modularized and the interface is standardized. It is also proposed that the future furnace should be able for quick reconfiguration through technical integration.
2014, 34(2): 137-142.   doi: 10.11728/cjss2014.02.137
Abstract(1057) [PDF 539KB](0)
Abstract:
With the Cluster observations of a quasi-parallel shock on 16 March 2005, relationship between the upstream low-frequency waves and the energetic ions (about several keV) has been studied. The observation results show that there are full of waves in the upstream of the shock which can interact with the upstream plasma. The differential energy flux of energetic ions in the upstream is dependent on the magnetic field strength of these waves. The energetic ion energy flux is higher in the regions with a weaker magnetic field. The possible explanation is that the ions can be trapped by the nonlinear upstream waves. Then the energetic ions were accelerated by the electric field every time when they bounced in these nonlinear waves. Our observation results are consistent with the recent hybrid simulation results.
2013, 33(5): 554-560.   doi: 10.11728/cjss2013.05.554
Abstract(1874) [PDF 2473KB](1)
Abstract:
It is important to calibrate the system errors of precise-measurement radar for the aim of ensuring its measurement precision. The satellite calibration method for radar system error is a new method by measuring optical tracking satellites. In this paper, the key algorithm of satellite calibration method based on least-square estimation is analyzed and deduced. Then, the satellite calibration system is designed. Finally, the algorithm is simulated, according to the value of radar system error parameter obtained with traditional calibration method, and the simulation results are analyzed. It shows that the satellite calibration technique based on least-square estimation method is effective.
2014, 34(6): 765-772.   doi: 10.11728/cjss2014.06.765
Abstract(806) [PDF 922KB](3)
Abstract:
Solar active region has close relationship with solar flares and solar proton events. In order to better understand the complicated relations between them as well as to build a concrete foundation for the forecasting of solar flares and solar proton events, the Principal Component Analysis (PCA) method is adopted to analyze the main parameters of solar active regions during 2007-2010. The parameters selected include sunspot magnetic classification, McIntosh classification, sunspot group area, 10.7 cm radio flux, flare index, the position of proton flares and soft X-ray flare intensity. A total of 81 principal component scores are obtained and compared with the solar proton event peak flow and annual average sunspot, 10.7 cm radio flux annual average, and it is found that the similarity is very high. The statistic results show that the principal component scores can represent the strength of solar activity to some extent.
2014, 34(2): 143-153.   doi: 10.11728/cjss2014.02.143
Abstract(1017) [PDF 482KB](0)
Abstract:
Comparison of regular (diurnal, seasonal and solar cycle) variations of high-latitude,mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron density and the peak height. The local empirical models were derived from the hand-scaled ionogram data recorded by DPS-4 digisondes located at Norilsk (69°N, 88°E), Irkutsk (52°N, 104°E) and Hainan (19°N, 109°E) for a 6-year period from December, 2002 to December, 2008. The technique used to build the local empirical model is described. The primary focus is diurnal-seasonal behavior under low solar activity and its change with increasing solar activity. Both common and specific features of the high-latitude (Norilsk), mid-latitude (Irkutsk) and low-latitude (Hainan) regular variations were revealed using their local empirical models.
2018, 38(4): 437-443.   doi: 10.11728/cjss2018.04.437
Abstract(714) [PDF 454KB](3)
Abstract:
The Correlation Coefficients (CC) between the time integral of solar Soft X-Ray (SXR) flux and the intensities of Solar Proton Events (SPE) in 0°W-39°W, 40°W-70°W and 71°W-90°W longitudinal areas have been calculated. The results show that the CC has its largest value. The property of CC is consistent with the concept that the largest flux of flare-accelerated particles can only be observed in the longitudinal area well magnetic connected with the observer. The results suggest that solar flares contribute to the production of SPE, namely that E ≥ 10MeV protons may be accelerated by the concurrent flares at the early phases of SPE.
2009, 29(1): 145-149.   doi: 10.11728/cjss2009.01.145
Abstract(3177) [PDF 613KB](3)
Abstract:
Two experiments on pool boiling in microgravity have been conducted aboard the Chinese recoverable satellites. Ground-based experiments have also been performed both in normal gravity and in short-term microgravity in the Drop Tower Beijing. A thin platinum wire and a plain plate were used as heaters, respectively. Steady boiling of R113 on the wire was studied with a temperature-controlled heating method, while quasi-steady boiling of FC-72 on the plate was investigated with an exponentially increasing heating voltage. In the first case, slight enhancement of heat transfer is observed in microgravity, while diminution is evident for high heat flux in the second one. Lateral motions of bubbles on the heaters are observed before their departure in microgravity. The surface oscillation of the merged bubbles due to lateral coalescence between adjacent bubbles drives it to detach from the heaters. It's also discussed about the Marangoni effect on the bubble behavior.
2008, 28(6): 578-583.   doi: 10.11728/cjss2008.06.578
Abstract(2928) [PDF 916KB](6)
Abstract:
Four-Dimensional 8PSK Trellis-Coded Modulation (4D-8PSK-TCM) is recommended as an efficient coded modulation standard for the Earth Exploration Satellite Service (EESS) 8025-8400 MHz band by the Consultative Committee for Space Data System (CCSDS). The advantage of 4D-8PSK-TCM is that coding gains can be achieved without expanding the bandwidth relative to the un-coded signal set. In this paper, the 4D-8PSK-TCM system with the modulation efficiency of 2.5 bit/symbol and its Viterbi decoding are presented and the Viterbi decoding algorithm is implemented on Matlab Simulink. During the algorithm implementation, an auxiliary trellis is introduced to reduce greatly the number of computations of metrics of each path. In this way, there are only 64 comparisons to compute the metrics in comparing with the 2032 comparisons required in a directly computing approach.
2013, 33(6): 664-671.   doi: 10.11728/cjss2013.06.664
Abstract(977) [PDF 1153KB](1)
Abstract:
SFODB is used to solve the data exchange for payload of high data rates in spacecraft and transmit mass detector data, which is proposed by the United States Department of Defense. It is a high-speed aerospace data bus based on commercial Asynchronous Transfer Mode (ATM). In its physical layer, the fiber link connects many FBIU units and single CFBIU unit to compose a ring network. The distance between each node cannot exceed 100m, and the data rate ranges from 200Mbit·s-1 to 1Gbit·s-1. The data bus has very high real-time performance and reliability, and its network size as well as the performance is better than others. This paper introduces the characteristics and latest development status as well as the technical approach of SFODB up to now. It is suggested that an spacecraft internal data bus should be designed as the backbone data network architecture based on SFODB, such as for the satellites and other spacecrafts. The network can complete spacecraft internal reliable data transmission with hierarchical classification for payload. Finally, we give some guidance for research and application of SFODB in the future, some highly reliable design concepts about internal bus in spacecraft may refer SFODB.
2009, 29(4): 397-401.   doi: 10.11728/cjss2009.04.397
Abstract(2413) [PDF 523KB](2)
Abstract:
Polar Mesosphere Summer Echoes (PMSE) are very strong radar echoes from altitudes near the polar summer mesopause. ECT-02 is carried out when PMSE in polar mesopause was occured. Based on the experiment results of ECT-02, the electron number densities and dust charge number densities are deduced in the paper. The data will provide a good basis to study various features of PMSE. By analyzing the data, one can find that dusty plasma in polar summer mesopause is weakly ionized and weakly coupled. The variable disturbance of electron density is used to explain the generation mechanism of PMSE. The stronger disturbance of the electron density corresponds to the stronger radar echoes, and when the disturbance becomes small, the radar echoes become weak, even disappear.
2011, 31(1): 106-111.   doi: 10.11728/cjss2011.01.106
Abstract(2357) [PDF 704KB](2)
Abstract:
Designers of space-based systems face unique challenges to insure each unit against failure. FPGA are used gradually in the aerospace field since it is invented with abundant I/O pins and flexible design margin. Many manufactures have been improving those space-qualified FPGA devices to adapt the aerospace high-radiation environments. FPGA devices based on SRAMs have to load configuration data from external PROMs on power-up before the logic is activated. However, not each batch or each device can be configured successfully with zero-failure. This paper explores every possible factor such as environment temperature, signal integrality, configuration rate and so on. Aiming at Xilinx FPGA devices, this paper provides a series of safeguard solutions for higher reliability of configuration. It has significant reference value in aerospace application fields for its feasibility and reliability.
2015, 35(4): 415-423.   doi: 10.11728/cjss2015.04.415
Abstract(708) [PDF 3448KB](5)
Abstract:
A statistical study has been conducted on all the geomagnetic storms caused by Coron Mass Ejection (CMEs) which are associated with flares from January 2010 to December 2012. The following results are obtained. The initial locations of CMEs mentioned above are distributed from 45°E to 45°W in solar longitude, accounting 78.95% of the total. Besides, the CMEs located in the west hemisphere are more likely to cause geomagnetic effects. X-class flares are more likely to be geo-effective, while flares in other classes have much lower probability. Geomagnetic storms will be observed in two or three days after 60% of X-class flares eruption. Therefore, more attention should been paid on X-class flares. By analyzing all the X-class flares erupted during this period, it is found that for the X-class flares located from 45°E to 45°W in solar longitude, if there is no disturbance on the solar surface (EUV wave) during eruption, the probability of the occurrence of geomagnetic storms after the flares will be very small. Therefore, a new method for geomagnetic storm forecasting by analyzing the Sun surface observations has been proposed.
2015, 35(5): 556-565.   doi: 10.11728/cjss2015.05.556
Abstract(1057) [PDF 6969KB](0)
Abstract:
In the present work, variations of ionospheric Total Electron Content (TEC) are investigated and compared with applying Empirical Orthogonal Functions (EOF) on the dataset from the Global Ionospheric Maps (GIMs) which are produced by Jet Propulsion Laboratory (JPL) over two concerned areas: the North America (30°N-50°N, 140°W-50°W) and East Asia (42.5°N-57.5°N, 65°E-140°E). The first three EOF components attribute about 99.57% and 99.79% to the total variations separately, and spatial-temporal features manifested by each EOF components are similar for the two areas: the first order EOF component for both areas represents semiannual variation which is strongly modulated by the solar activity; the second order component exhibits pronounced east-west longitude difference to the zero valued geomagnetic declination line, and these east-west longitude differences are coincidently consistent with plasma drift velocity caused by thermospheric zonal wind; the third order component demonstrates latitudinal variations possibly influenced by plasma drift velocity caused by thermospheric meridional wind. Results of the this paper are useful for understanding the physics mechanism of the ionospheric variations.
2005, 25(3): 208-211.   doi: 10.11728/cjss2005.03.208
Abstract(1909) [PDF 1266KB](5)
Abstract:
2013, 33(6): 617-623.   doi: 10.11728/cjss2013.06.617
Abstract(838) [PDF 2624KB](0)
Abstract:
Mastering spatial and temporal distribution of geoelectric field is the premise of researching and preventing adverse effect on technology systems due to geomagnetic induced current. This paper presents a model for geoelectric field on the basis of sparse geomagnetic observation data in China. Firstly, the model of equal Spherical Elementary Currents System (SECS) is used to represent ionospheric current. Then, the hybrid algorithm of SECS and Complex Image Method (CIM) is proposed to calculate the geoelectric field and the magnetic field due to geomagnetic disturbance. The method provided can be used to calculate the fields at any time, any place during magnetic storms. To test and validate the approach put forward, the observation geomagnetic data at Umq, KSH, GRM and JYG were applied, the induced fields in northwest area were calculated, and the errors between the measurement and calculation were analyzed as well. The results of geoelectric field are consistent with that of the plane wave method, which verifies the algorithm proposed. The results can be directly used to calculate the geomagnetically induced currents flowing in power system, which is of great significance in the hazards assessment of power systems.
2010, 30(5): 464-467.   doi: 10.11728/cjss2010.05.464
Abstract(2252) [PDF 137KB](2)
Abstract:
During the past two years, space environment has achieved great development in space environment monitoring, model research, system developing and space environment service in China. In this paper, we mainly introduce space environment safety support for Shenzhou-7 manned spacecraft, two typical space environment operation platforms, and the advance of Re-locatable Atmospheric Observatory (RAO). At the last part of this paper, the Sub-committee on Space Environment(SSE) which was set up in 2009 under the Technical Committee on Space Technology and Operation of Standardization Administration of China is briefly introduced.
1997, 17(3): 212-219.   doi: 10.11728/cjss1997.03.212
Abstract(1711) [PDF 742KB](1)
Abstract:
A theoretical low-latitud ionospheric model is presented. The continuity andmomentum equations of O+, H+ are solved, using operator splitting difference schemeon the fixed grid points distributed along the magnehc fields. Molecular ion densitiesof N2+, O2+, NO+ are calculated under the assumption of photochemical equilibrium.The modeling results fairly reproduced the gross features of daily development ofequatorial anomaly observed in East Asia under equinochal, solar maximum conditions.It is also shown that HWM90 model estimates much too large nighttime windvelocities at low latituds in East Asia, and the vertical drift velocity in East Asiamay be smaller than that in American region.
2008, 28(4): 316-325.   doi: 10.11728/cjss2008.04.316
Abstract(2363) [PDF 4171KB](9)
Abstract:
2015, 35(5): 618-625.   doi: 10.11728/cjss2015.05.618
Abstract(919) [PDF 3091KB](7)
Abstract:
In order to suppress infrared telescope astronomy disturbance caused by the satellite payload, it is needed to design vibration reduction device for the telescope. Therefor a viscous fluid damper used in space is designed, which could be sealed reliably and adapted to the space environment well. Firstly, a damping calculation model based on the theory of fluid mechanics is built. Then, the structure of the damper is designed, and parameters of the spring sheet which was a core component belonging to the damper, are optimized. A set of prototype was manufactured, and a finite element model of the vibration isolation system was created to get the system's first two models. Finally, the simulation results are compared with the experimental results. According to the analysis results, it can be seen that the damper's stiffness characteristics and damping characteristics can meet the design requirement. The theory analysis results coincide with the experimental results, which proves that the finite element model is precise and the prototype has guidance value in engineering design.
2011, 31(4): 482-491.   doi: 10.11728/cjss2011.04.482
Abstract(2835) [PDF 1208KB](5)
Abstract:
The Moon retains the information of initial period, because its geological activity was ceased 3.1billion years ago. This information is very important for us to recognize the formation and evolution of the Moon, the earth and even the solar system. On the basis of initial study and Chang'E-1 CCD images, the geological, topographic and geomorphologic features of the main tectonic patterns on the Moon are introduced. The two important kinds of structures on the moon are circular tectonics and linear tectonics. Circular tectonics are the annular appearances on remote sensing images displayed through architecture and color, which are the most striking features of lunar images. This article studies the formation of Mons Rümker, Hainzel Crater, King Crater and the fracture at the bottom of Humboldt Crater, and then, analyzes the difference in lunar crater both near and far side, the South and North Pole. Linear tectonics refer to those structures extended as linear on lunar surface, which can reflect the global or territorial stress condition and stress field of the lithosphere and tectonic forms on the planets. This article also studies the echelon structure nearby the Cauchy Crater, step scarp of Mare Humorum, regional fault nearby the Hippocrateson Crater, fault structures along Apennine Mountains, crater chain at the bottom of Davy Crater, Rima Hyginus and Vallis Alpes. The result shows that the Chang'E-1 CCD images have sharp details and rich information which are clear enough to research the lunar tectonic features.
2018, 38(4): 452-459.   doi: 10.11728/cjss2018.04.452
Abstract(832) [PDF 2714KB](2)
Abstract:
The ionospheric kinetic numerical model is expressed as the solution to the temporal evolution of the electron density profile. The ion continuity and the momentum equations, the solar ionization, star ionization, coronal ionization, interstellar background ionization and meteor ion flow are all considered. The main kinetic process and photochemical process of Es layer are analyzed synthetically. The effects of neutral component collision, electric field, metal ion and molecular ion on the ion distribution are also included. In the paper, a one-dimensional time-dependent model of the ionospheric Es has been developed on the basis of the wind shear theory. The ion production rate and the distribution of the vertical ion velocity in height and time are simulated by the model. The variations of ion density profile in 24 hours are also obtained. According to the observation results of winds by coherent scattering radar in Kunming station, the time and space dependent of electron density of Es (Ne) is acquired by the model. Then the f0Es are given by the conversion of Ne, and the retrieval results are in good agreement with the contemporaneous ionosonde data in Kunming.
2008, 28(3): 230-235.   doi: 10.11728/cjss2008.03.230
Abstract(2167) [PDF 3688KB](4)
Abstract:
The characteristics of the stratospheric quasi-zero wind layer and its seasonal and geographic variation features over China are obtained by using the ERA-40 reanalyzed wind data which are provided by ECMWF. Results show that quasi-zero wind layer generally exists at the height range of 18--25 km and some variation of the height of the zero wind line would happen when the time or location change. According to the latitudinal variation of the quasi-zero wind layer, the atmosphere over China could be divided into three parts to discuss its features: low-latitude area (5ºN~20ºN), transition area (20ºN~32.5ºN), middle- and high-latitude area (32.5ºN~55ºN). The quasi-zero wind layer may exist in winter and at the beginning of spring in low-latitude area. In middle-and high-latitude area, the quasi-zero wind layer may be found at the end of spring and in summer. The quasi-zero wind layer in transition area relates to the equatorial quasi-biennial oscillation (QBO). During the easterly phase of QBO, the characteristics of the transition area are similar to that of the middle-latitude area, while during the westerly phase of QBO, its characteristics are similar to that of the low-latitude area. The quasi-zero wind layer varies little with the longitude. The longitudinal variation of the height of zero wind line may not exceed 2 km. However, this variation is relatively larger in the transition area.
1998, 18(3): 228-234.   doi: 10.11728/cjss1998.03.228
Abstract(1725) [PDF 467KB](2)
Abstract:
Good prediction results for geomagnetic indices have been obtained with the use of artificial intelligent(AI)technique,especially by the neural networks.While a common Problem is how to increase the advance time of the prediction.It is true that the earlier of the prediction, the less possibility to predict the detail of an impending event.Therefore threshold prediction should be also a very helpful and useful method for early time prediction when forecasting the occurrence of the events which bring disaster on the cormmunication,power transmission and satellite life etc. Threshold prediction means the predicted events are over a threshold,such as-120nT. In this paper BP model of neural networks is used to predict the major storms 4 hours ahead, with the minimum of Dst less than-120nT. The inputs are 13 solar wind parameters and geomagnetic AE and Dst.The ought is I for major storms or 0 for non major storms. The results show that the threshold prediction by neural networks can give accurate prediction for major storm occurrence.
2009, 29(2): 188-194.   doi: 10.11728/cjss2009.02.188
Abstract(3893) [PDF 756KB](1)
Abstract:
This paper presents a new idea to determine polynomial ionosphere model with the circumstance that lacking of real observation data in special region. Besides real observation data, grid data calculated by global ionosphere model has been used as a background. The weight of two kinds of data has been discussed, and then mathematical model has been established. Secondly, the model continuity between two segments have been discussed, and then a smoothing method to calculate ionosphere delay has been studied, which uses two groups of time weighting neighbored model coefficients. Finally, the availability of the model was proved by mathematic experimentation.
2018, 38(5): 665-693.   doi: 10.11728/cjss2018.05.665
Abstract(499) [PDF 348KB](4)
Abstract:
During the past two years (2016-2018), great achievements have been made in the Chinese research of interplanetary physics, with nearly 100 papers published in the academic journals. The achievements are including but not limited to the following topics:solar corona; solar wind and turbulence; filament/prominence and jets; solar flare; radio bursts; particle acceleration at coronal shocks; magnetic flux ropes; instability; instrument; Coronal Mass Ejections (CMEs) and their interplanetary counterparts; Magnetohydrodynamic (MHD) numerical modeling; solar energetic particles and cosmic rays. The progress further improves our understanding of the eruptions of solar activities, their evolutions and propagations in the heliosphere, and final geoeffects on our Earth. These results were achieved by the Chinese solar and space scientists independently or via international collaborations. This paper will give a brief review of these achievements.
2012, 32(2): 230-237.   doi: 10.11728/cjss2012.02.230
Abstract(2322) [PDF 1366KB](5)
Abstract:
Gravitropism is an important physiological response and an essential mechanism for plants to maintain the normal growth and development on earth. In the life cycle of higher plants, seed development is a key process, but whether gravity can affect the development of seeds has not been confirmed. In this study, the development of siliques and seeds of Arabidopsis under the 3D clinostat rotated condition was analyzed to examine whether seed development including formation of embryos and the activities of metabolism is affected by the altered gravity condition. Our results showed that in the 3D clinostat rotated treated Arabidopsis plants, the morphology of siliques showed an irregular curvature, and the cell division and elongation of suspensor were inhibited. The content of soluble carbohydrates and starch in the young and mature seeds obviously increased, while the content of salt soluble protein decreased. In addition, developing seeds at globular stage are most sensitive to the 3D clinostat rotated treatment with the inhibition of cell division and elongation of the suspensors. Suspensors are important for the transportation of nutrients into embryos and abnormal development of suspensor under the clinostat rotation condition might cause seed abortion.
2014, 34(2): 201-207.   doi: 10.11728/cjss2014.02.201
Abstract(1071) [PDF 949KB](2)
Abstract:
Faults are unavoidable for in-orbit satellites. They are able to be detected by carefully analyzing the telemetry data from these satellites. It is obvious that a good performance of anomaly detection algorithm is very important. This paper presents a new approach which takes the advantage of the similarity of preceding telemetry data to detect current anomaly. Because of its adaptive checking criteria, it can find some faults that cannot be found by some traditional methods. Most of important thing of this algorithm is that no prior knowledge about any particular satellite is needed except telemetry data themselves. In order to prove its availability, we use this new approach to process telemetry data from a China on-orbit satellite in 2012 and a fault is detected instantaneously.
1994, 14(1): 70-75.   doi: 10.11728/cjss1994.01.070
Abstract(1632) [PDF 355KB](2)
Abstract:
Using Gylder-Meshcherckii equation and Eddington-Jeans law, the influence of solar mass-loss on planetary orbits is discussed in this paper. It is shown that solar mass-loss will cause the first-order secular and periodic terms in the semimajor axis a, the first-order periodic and secon-order mixed terms in the eccentricity, and the first-order periodic, second-order secular and mixed terms in the argument of perihelion of planetary orbits. The secular variation of the semimajor axis of planetary orbits should influence the stability of solar system.
2006, 26(4): 257-263.   doi: 10.11728/cjss2006.04.257
Abstract(2089) [PDF 377KB](4)
Abstract:
There is the Triangle Size Effect （TSE） in wind measurements with Spaced Antenna （SA） method due to electronic noise and ground clutters etc. Another possible cause （non-stationary of atmosphere） of TSE and the mechanism of its effect to wind measurements was discussed in this paper. The work also presents Increment＇s Cumulant Approach （ICA） to eliminate the nontationary of atmosphere and ground clutter based on the analysis of the causes of TSE; the analytical expression of one dimension mean velocity can also be obtained by the special case of Increment＇s Cumulant Approach （the 2nd order zero-lags ICA）. In addition the high order （k ≥ 3） cumulant of increment are proposed to suppress Gaussian noise. The comparisons between FCA and ICA with non-stationary and ground clutter by numerical simulations show that the measurement errors of ICA are much less than those of FCA by comparing mean horizontal velocities （output of simulations） and input velocities of mode.
2014, 34(2): 214-218.   doi: 10.11728/cjss2014.02.214
Abstract(1002) [PDF 543KB](1)
Abstract:
Chemical release at ionospheric altitudes is one of the most important ways to carry out active experiments for investigation of ionosphere features. A new rocket-borne SF6 releaser is studied. This releaser has many advantages such as small size, light weight, low requirements for the launch platform, and when the device weight is 6kg, 2kg SF6 can be released. By means of simulation, the diffusion process of neutral gas and relevant chemical reactions in ionosphere are calculated, and the effect of SF6 releases is investigated．Results showed that the designs scheme of the SF6 releaser is feasible and consistent with domestic rocket-borne platform and conditions in China, hence has high application value.
2018, 38(4): 546-552.   doi: 10.11728/cjss2018.04.546
Abstract(656) [PDF 2159KB](5)
Abstract:
Future manned spacecraft needs to provide a long-term working environment, in which sterile water is the guarantee of life and health. The sterilization module is installed at the end of the water treatment system to release the specified concentration of silver ions to the purified water, playing a role of sterilization and long-term preservation of the water. According to the exchange basin using standard k-ε model standard wall function, the calculating model of flow field and concentration field of silver ions have been set up for the 600mL·min-1 flow condition as the water flows through the wall. The sterilization module electrode alternating exchanges with 30s period, and draws the concentration change. For meeting the actual conditions, the model is solved by iterative method. By analyzing the production rate of silver ion velocity, the highest concentration of silver ions locates at the anode surface near the cathode. Anode-cathode converting repeatedly can effectively reduce the silver ion concentration near the electrode surface. That is, the conversion has transmission effect to the decreasing of silver ion concentration, and can be carried out repeatedly. There is no AgOH precipitation, and then the process parameters can be determined and the engineering design can be guided. Finally, according to the simulation results, the optimization suggest of the sterilization module is given.
2014, 34(6): 830-836.   doi: 10.11728/cjss2014.06.830
Abstract(1403) [PDF 2766KB](15)
Abstract:
Thermosphere atmospheric drag is the significant factor affecting most space operations of low Earth orbiter, especially, an inherent 15% formal error of empirical models has become the cumber to improve orbit calculations accuracy. Among the empirical models used in aerospace engineering, JACCHIA71 model, which has relative explicit physical bac kground and less parameters, is selected as a basic model. The temperature Tc and Tx, namely nighttime minimum of the global exospheric temperature and inflection point temperature, are chosen as the estimated parameters during the differential correction. The condition equation of density with respect to these two temperatures is established, and the least square solutions are given as well. The model accuracy improvement is almost enhanced by over an order of magnitude after calibration using CHAMP data. Orbit prediction accuracy of TG01 with the position bias of 2 km is also improved to 1.3 km through temperature corrections using in-site detecting data. All of these case studies validates the effectiveness of the calibration algorithm.
2009, 29(3): 257-261.   doi: 10.11728/cjss2009.03.257
Abstract(3446) [PDF 603KB](4)
Abstract:
Based on a single-fluid MHD model, this paper has studied the global magnetic field structure in the near-Mars space, and investigated the influence of the Martian crustal magnetic fields on the magnetic field structure. Mars bow shock, Magnetic Pileup Region are produced when the solar wind flows over Mars. The interplanetary magnetic field lines are curved and draping' around the planet. The majority of magnetic field lines bypass over two poles, leaving V shaped' structure in the wake behind Mars. Near the surface of Mars, the local crustal magnetic fields also have noticeable influence on the magnetic field structure. The crustal magnetic fields at different positions, with different intensities form the dissimilar magnetic filed structure and mini-magnetospheres when interacting with the solar wind. The towed mini-magnetosphere and the mini-magnetosphere with open magnetic lines are illustrated in the paper. The local crustal magnetic fields change the morphology of the magnetic field, and accordingly may play an important role in determining the plasma distribution.
2018, 38(4): 517-523.   doi: 10.11728/cjss2018.04.517
Abstract(766) [PDF 2750KB](6)
Abstract:
The soot formation in a coflow ethylene/air laminar flame at 1g/0g (normal gravity and zero gravity) has been studied using particular fuel oxidation and PAH mechanism. The nucleation process is regarded as the dimerization of two large PAH, and HACA mechanism is used to describe the surface growth process. The collision of soot and PAH is mainly taken into account for the condensation process in soot surface. The initial nucleation, soot surface growth, condensation and oxidation are simulated with a discrete sectional aerosol model to capture the different size soot with different mass. The calculating results show that the peak temperature of the flame at 0g decrease by 230K, whereas the peak soot volume fraction is nearly twice larger than that of the 1g condition. This paper also studied the distribution of precursors (C2H2 and PAH), nucleation rate, surface growth rate, and condensation rate under microgravity. It is indicated that the condensation is the major process of soot formation in the centerline of flame for both 1g and 0g conditions, and it plays a more important role under microgravity. The average diameter of soot is lager due to long residence time under microgravity.
1998, 18(2): 174-179.   doi: 10.11728/cjss1998.02.174
Abstract(1686) [PDF 259KB](0)
Abstract:
In this paper, the control scheme is discussed for a free-floating space manipulatror,based on the augmented statefeedback control model. The scheme of robust variable structure control is proposed for a free-floating space manipulator,whose load parameters is uncertain, to track the desired trajectory of workspace. It is demonstrated by the simulation that the control scheme is efficient.
2018, 38(4): 492-501.   doi: 10.11728/cjss2018.04.492
Abstract(899) [PDF 3209KB](11)
Abstract:
Wuhan Mesosphere-Stratosphere-Troposphere (MST) radar is a radio atmosphere detection radar deployed by the Chinese Meridian Project. As the frequency is in VHF band, the echoes are sensitive in all their aspects. Such echo characteristics are much more obvious in the Upper Troposphere and Lower Stratosphere (UTLS), which provides a practical approach to investigate the atmosphere dynamics. Observations of echo characteristic during a cold front are obtained by Wuhan MST radar in mid-latitude in April 2016. The experiment results show that the typical feature of the echo aspect sensitivity is significantly changed compared with that of normal days. Reasons of the echo anomaly are studied by analyzing echo characteristics variations, wind field spatial distributions, turbulence generation mechanisms and Inertia Gravity Waves (IGWs) effects. The result demonstrates that the dissipating (or even breaking) of upward IGWs coming from convection system might feed the long-time persistence of Kelvin-Helmholtz (K-H) instability, which further tilts the horizontal reflection layer and results in the intense turbulence and the echo enhancement.
2018, 38(5): 820-828.   doi: 10.11728/cjss2018.05.820
Abstract(837) [PDF 1323KB](2)
Abstract:
With the human space exploration activities, space life science is an emerging interdiscipline, which covers a wide range of researches. Based on our country's manned space station and recoverable satellite science experimental platform, the development of space life science research is very important to acquire new knowledge or new technological innovation, to give further services to the human space exploration activities, to improve the national economic and social development. Both ground-based and flight applied studies were continuously performed in the previous 2 years. Here, we review and summarize the researches on space life sciences contributed by Chinese scientists.
2009, 29(1): 17-22.   doi: 10.11728/cjss2009.01.017
Abstract(4765) [PDF 627KB](5)
Abstract:
The influences of impurity on surface morphology and growth kinetics of tetragonal lysozyme crystals were studied. There was a significant difference in morphology of 2D islands on a {110} face when the impurities existed. Impurities significantly decreased the normal growth rates of both the {110} and {101} face. F-lysozyme decreased the normal growth rate of both the {110} face and {101} face. The values of kinetic coefficient of the steps, surface free energy, and ledge free energy of the step edge were determined.
2018, 38(4): 469-481.   doi: 10.11728/cjss2018.04.469
Abstract(706) [PDF 12947KB](2)
Abstract:
In order to analyze the characteristics of the deep convection-induced stratospheric gravity waves in Chinese continental region, a stratospheric gravity wave process, which is observed by the satellite Aqua/AIRS and accompanied with the heavy rainstorm process on July 25th, 2011 in Rushan, is simulated using the mesoscale numerical WRF (Weather Research and Forcasting) model. The analysis of the vertical velocity field and the temperature disturbance field of the mode output show that the structure of the torrential wave in the stratosphere is mainly concentrated in the east of the precipitation cloud system, and the horizontal influence range is more than 1000km. With the increase of the height, the structure of the torrential wave tends to close, and the wave energy is also significantly enhanced. The results of power spectrum analysis based on Fast Fourier Transform (FFT) show that the stratospheric gravity wave induced by the storm at 35km has the horizontal wavelength of about 1000km and the vertical wavelength of 5~10km. Finally, the parameterized forcing in gravity wave uploading process is quantifiably reflected by analyzing the vertical transport of momentum flux reflects.
2015, 35(5): 581-587.   doi: 10.11728/cjss2015.05.581
Abstract(925) [PDF 5470KB](1)
Abstract:
By utilizing data obtained on Chinese satellite in the middle Earth orbit from solar activity descending phase to solar activity ascending phase, the properties of high energy electron environment in the middle Earth orbit are analyzed, such as spatial distribution, flux intensity, temporal variations, and response to geomagnetic storms. The investigating results indicate that the spatial distribution of high energy electron in the middle Earth orbit is stable; the fluxes of electrons decrease with energy increasing; the high energy electron environment is a dynamical system which disturbs evidently on different timescales; the evolvement of this system is stimulated by geomagnetic storms, but the correlation between the evolvement and the storms is nonlinear.
1987, 7(2): 85-94.   doi: 10.11728/cjss1987.02.085
Abstract(1544) [PDF 627KB](0)
Abstract:
Under the condition of an unstable, inhomogeneous and anisotropic ionosphere, some relations among the dynamic parameters of the ionosphere and the observables of HFradio echoes reflected from the ionosphere are derived from the general ray equations. On the basis of these relations, a method is proposed to invert the height profile of the electron density, N(Z), and the height profile of the normal velocity, V(Z) of the constant electron density surface from the observed Dopplionogram, gonionogram, ionogram and rangionogram. Furthermore, comparing the possible combination of the radio wave obserables which are necessary and sufficient for the determination of the height profiles of V(Z) and N(Z), the authors suggest a new operation mode of ionosonde to observe the large scale ionospheric disturbances such as the gravity waves from a single station. This may be the theoretical basis for data analysis and instrumental improvement of modern ionosonde.
2011, 31(2): 125-149.   doi: 10.11728/cjss2011.02.125
Abstract(2253) [PDF 1177KB](0)
Abstract:
Both theory and simulation have played important roles in defining and illuminating the key mechanisms involved in substorms. Basic theories of magnetic reconnection and of interchange and ballooning instabilities were developed more than 50 years ago, and these plasma physical concepts have been central in discussions of substorm physics. A vast amount of research on reconnection, including both theoretical and computational studies, has helped provide a picture of how reconnection operates in the collisionless environment of the magnetosphere. Still, however, we do not fully understand how key microscale processes and large-scale dynamics work together to determine the location and rate of reconnection. While in the last twenty years, it has become clear that interchange processes are important for transporting plasma through the plasma sheet in the form of bursty bulk flows and substorm expansions, we still have not reached the point where simulations are able to realistically and defensibly represent all of the important aspects of the phenomenon. More than two decades ago it was suggested that the ballooning instability, the basic theory for which dates from the 1950s, may play an important role in substorms. Now the majority of experts agree that regions of the plasma sheet are often linearly unstable to ideal-MHD ballooning. However, it is also clear that kinetic effects introduce important modifications to the MHD stability criterion. It is still uncertain whether ballooning plays a leading role in substorms or has just a minor part. Among the different types of simulations that have been applied to the substorm problem, global MHD codes are unique in that, in a sense, they represent the entire global substorm phenomenon, including coupling to the solar wind and ionosphere, and the important mechanisms of reconnection, interchange, and ballooning. However, they have not yet progressed to the point where they can accurately represent the whole phenomenon, because grid-resolution problems limit the accuracy with which they can solve the equations of ideal MHD and the coupling to the ionosphere, and they cannot accurately represent small-scale processes that violate ideal MHD.
2009, 29(1): 124-129.   doi: 10.11728/cjss2009.01.124
Abstract(3702) [PDF 646KB](4)
Abstract:
Twenty-three recoverable satellites have been successfully launched in China since 1975. A number of microgravity experiments were successfully performed by utilizing the piggyback capability of the satellite apart from the main task during the previous flights. An overview of the recoverable satellite development in China is given in the present paper. Main characteristics of the Chinese recoverable satellites and the scientific experiments completed onboard the satellites are discussed. The environment condition and the interface between the working payload and satellite during different design and manufacture phase are also briefly described. Future trend of platform technology and the applications are presented.
2018, 38(4): 553-559.   doi: 10.11728/cjss2018.04.553
Abstract(1119) [PDF 1141KB](21)
Abstract:
Using broadcast ephemeris to calculate the velocity vector of navigation satellites is a necessary condition for GNSS real-time velocity determination. In this paper, the accuracy of velocity vector calculated by Beidou broadcasting ephemeris only with position observations is analyzed, and the calculation formula of velocity vector with Beidou 18-element model is deduced. Based on one year data of 13 Beidou satellites in orbit, the accuracy of velocity vector calculated by broadcasting ephemeris is obtained. The results show that the maximal velocity error calculated by the 18-element model is in the order of 10-4-1. At the same fitting period, the velocity accuracy of GEO and IGSO satellites is higher than that of MEO. By analyzing position residual sequence, the conclusion is drawn that the velocity accuracy computed by broadcast ephemeris is very high because of little position residual with smooth change trend. The analysis and calculation results in this paper verify the effectiveness of fitting BDS broadcast ephemeris only using position observations.
1999, 19(4): 334-341.   doi: 10.11728/cjss1999.04.334
Abstract(2422) [PDF 556KB](2)
Abstract:
Some characteristics of winds at height of 20-80 km in the Chinese area areobtained using the Nimbus-7 SAMS temperature data from 1979 to 1981 by thegeostrophic balance thermal wind equations. It is shown that the winds from satellite are coincident roughly with the winds from Chinese rocket measurements andthe derivation of winds with the satellite temperature data is effective in obtainingclimate characteristics of winds at height of 20--80 km in Chinese area. These results show the difference between the zonal mean winds above China with the zonalmean wind of CIRA-1986 is obvious. The longitudinal difference of the winds atheight 20--80km over China is also evident. The effect on the middle atmospherewinds by topography of this area can not be disregarded. The meridional wind andvariations of winds over China is discussed.
2014, 34(4): 483-488.   doi: 10.11728/cjss2014.04.483
Abstract(1293) [PDF 3157KB](1)
Abstract:
Satellites whose attitude is inertial space orientation cannot keep the transmitting antenna beam accurately pointing to the ground stations when the data transmitting device in the satellite is working. As a result, a new technical challenge of transmitting the payload data from the satellite to the ground stations in a high speed is brought forward. In this paper, a method using the transmitting antenna whose beam has proper width and pointing direction to resolve the problem is dedicated. For this aim, by simulating the satellite orbit with STK software, variation of the relative attitude of such satellites to the ground stations, as well as comparison on the data transmission time from the satellite to the ground stations at different beam width of the transmitting antenna, are researched. The key research is to develop an antenna whose gain is 0dBi in 140° angle of beam, and the link is designed to ensure a sufficient margin at the transmission rate of 85Mbit·s-1. As a result, under the constraint of space avionics miniaturization (10kg of mass, 80W of power consumption), the miniaturized antenna with wide beam and the solid-state power amplifier are designed to solve the problem of payload data transmission of satellites whose attitude is inertial space orientation.
1982, 2(2): 111-117.   doi: 10.11728/cjss1982.02.111
Abstract(1833) [PDF 718KB](1)
Abstract:
In this paper,the evolutionary relation between meteorites,meteonoids and asteroids or comets is discussed in our viewpoint on the origin of asteroids and comets.Both asteroids and comets are the'halffinished product' of the planets evolved from the primitive nebula,i.e.surviving planetesimals.They show differences in their evolutions,in their orbital characters and their physics-chemical properties only because they form in different places,under different environmental conditions.When volatile-rich comets moved into inner portion of the solar system,they could easily disintegrate into a great number of meteoroids.The surviving planetesimals in the asteroid region could be broken into fragments by collision.Those fragments and crumbs could turn into smaller asteroids or meteoroids.In fact,there is no strict limits between smaller asteroids and bigger meteoroids.Some fragments of planetesimals in the asteroid region would evolve into meteoroids and enter into the atmosphere of the earth,they could then ablaze out as meteors.Cosmic dust,which failed into the solar system from interstellar space,could also become meteoroids
2014, 34(6): 802-808.   doi: 10.11728/cjss2014.06.802
Abstract(1135) [PDF 3342KB](2)
Abstract:
Data recorded by GPS ionospheric scintillation monitors in Guangzhou (23.17°N, 113.34°E) and Maoming (21.45°N, 111.31°E) stations, which are situated near the northern crest of the equatorial ionosphere anormaly, has been used to study the day-to-day, month-to-month, local time and spatial variation characteristics of ionospheric amplitude scintillation during the period from July 2011 to June 2012. The results show that different intensity of amplitude scintillations has co mmon temporal variation characteristics. The scintillation activities with S4>0.4 and S4>0.6 mostly occur from 20:00LT to 24:00LT in spring and autumn. Spatially, scintillations distribute throughout the large region with the latitude from 18° to 27° and the longitude from 109° to 118° for Guangzhou and the latitude from 17° to 26° and the longitude from 107° to 116° for Maoming in the fall of 2011. However, scintillations mainly appear in a small area overhead in the spring of 2012 of both stations.
2018, 38(4): 482-491.   doi: 10.11728/cjss2018.04.482
Abstract(617) [PDF 5057KB](5)
Abstract:
The horizontal wind data observed by Fabry-Perot Interferometer (FPI) over Kelan, China, has been used to investigate the characteristics of wind and planetary waves at altitudes of 87, 97 and 250km. Firstly, the midnight winds have been compared with those from HWM07. The results are as follows. At 87 and 97km, the AO (Annual Oscillation) and SAO (Semiannual Oscillation) phases of zonal wind of FPI tend to consist with those from HWM07, while the phases of FPI meridional wind lag behind. Both the zonal and meridional FPI amplitudes are smaller. It shows large discrepancies between FPI and HWM07 winds, which reveals that the improvement of HWM07 model needs to further consider the influence of solar activity and interplanetary magnetic field. Secondly, the Lomb-Scargle analysis and the least squares harmonic fitting method have been used to derive the amplitudes of planetary waves at the three altitudes. At 87 and 97km, the 16-day waves are prominent at autumn, winter and spring during 2013-2014, while the 6.5-day waves tend to dominant spring and autumn. Both of the two planetary waves have weak amplitudes around mesopause. The amplitudes are stronger in meridional wind than zonal at 250km. Three typical planetary wave period bands of meridional wind show that the strongest amplitudes persist from May to October. This is consist with the results of ionospheric f0F2 oscillations.
2013, 33(6): 637-644.   doi: 10.11728/cjss2013.06.637
Abstract(1035) [PDF 1146KB](1)
Abstract:
The relation between the solar wind speed and the winter northern hemisphere circulation, characterized as Arctic Oscillation (AO), was investigated with the superposed epoch analysis method and the correlation analysis method on the day-to-day and seasonal time scale. The results showed that on day-to-day time scale, the decease of solar wind speed associated with the dip of AO could be significantly detected, which implied that there exist the linkage chain from solar wind speed to the tropospheric circulation mediated by relativistic electron. This process could be explained by the correlation of "space particle-global circuit-cloud microphysics". On seasonal scale, the winter mean of solar wind speed in past 48 winters took significant correlation with the AO index. To understand the linkage between Sun and the climate, we should collect all the detailed physical environment information from Sun to low atmosphere in the future.
1999, 19(1): 34-41.   doi: 10.11728/cjss1999.01.034
Abstract(1927) [PDF 516KB](3)
Abstract:
With the help of EISCAT radar data, auroral ionospheric electromagnetic parameters, such as convection electric field, conductivity tensor, and Joule heating rates etc. are calculated and analyzed for an intense magnetic storm (min.Dst<=-150nT) occurring in summer of a high solar activity year. An investigationis emphatically made on the relationship between the thermospheric Joule heatingin the E-region and frictional heating of ions in the F-region with the ionizationdepletion in the F-region. It is found that at the sector of eastward auroral electrojet in the afternoon, a maximum depletion of 70% in electron density occurs ataltitudes of 300-325 km, its occurrence lags just 5-10 minutes after the integatedJoule heating reaches to its mamximun of about 92 mW/m2 in the E-region and ionfrictional heating in the F-region, to its maximum, too.
2013, 33(6): 678-682.   doi: 10.11728/cjss2013.06.678
Abstract(727) [PDF 1197KB](2)
Abstract:
Based on the needs of Meridian Project of sounding rockets' electronic and electric field probe, a sleeve-type of boom deployment mechanism was designed. Structure scheme design, mechanical simulation analysis, single mechanical property test, the whole rocket matching mechanical test as well as the flight test validation of both electronic boom and the electric field boom showed that the boom technical scheme is reasonable and feasible, and the boom overall configuration, layout design and structure design can meet the requirements of technical index for scientific exploration. According to the scientific exploration mission needs and space restrictions of the installation on the sounding rocket, a wide range of innovative design and development are carried out in the structure style, deployment and motion mode, locking and fixed mechanism of the boom deployment mechanism, as well as its installation on the rocket and release, etc.
2018, 38(5): 640-649.   doi: 10.11728/cjss2018.05.640
Abstract(640) [PDF 165KB](0)
Abstract:
The Chinese Meridian Space Weather Monitoring Project (Meridian Project) is a ground-based geospace monitoring chain in China. It consists of 15 ground-based observation stations located roughly along 120°E longitude and 30°N latitude. In recent two years, using data from the Meridian Project, significant progress has been made in space weather and space physics research. These advances are mainly in four aspects:regional characteristics of space environment above China or along 120°E meridian line, coupling between space spheres at different heights and different physical processes, space weather disturbance and its propagation along the meridian chain, and space weather effects on ground technical facilities.
2012, 32(5): 739-749.   doi: 10.11728/cjss2012.05.739
Abstract(2150) [PDF 926KB](8)
Abstract:
Loop heat pipe with flat evaporator (Flat Loop Heat Pipe, FLHP) driven by capillary force and mechanical pumped two-phase loop (Tracker Thermal Control System, TTCS) are typical two-phase loop thermal control systems. The working principles of both FLHP and TTCS are discussed in this paper, and samples are tested. Also, dynamic models are built by both SINDA/FLUINT and Matlab/Simulink. The results show that both the FLHP and TTCS may have start-up problem, that the FLHP may have larger temperature oscillation, while the TTCS are more stable, that gravity has obvious effect on the FLHP performance, yet has no obvious effect on the TTCS performance, and that the FLHP with bi-transport loops has a better performance than that with single-transport loop, and the two radiators of the TTCS has the ability of self-adjust in mass flow rate and heat transfer. To choose a two-phase thermal control system, some items should be considered, such as the characteristic of the heat source, the life requirement, the temperature requirement, as well as the system size and mass, etc. Development of the two techniques may be cross-reference and complementary in future.
2013, 33(6): 651-658.   doi: 10.11728/cjss2013.06.651
Abstract(967) [PDF 1420KB](5)
Abstract:
As a major component of space radiation, ultraviolet radiation can extensively destruct terrestrial plants and aquatic. Real-time PCR technique has been widely used to detect the level of target mRNA expression when cell or tissues exposed to various types environmental stress. Choosing an appropriate internal control gene is important to accurately analyze the level of target gene transcription with real-time PCR technique. Therefore, our experiment tries to choose the most appropriate and stability reference gene from six traditional internal control genes, i.e., 18S rRNA, GAPDH, β-actin, β-tubulin, EF1-α and UBC in the Chlamydomonas reinhardtii under radiation conditions. The results showed that C. reinhardtii 18S rRNA gene expression is the most unstable through GeNorm analysis, but β-actin and GAPDH gene were finally selected as a pair of suitable internal control genes in expression analysis, with which more accurate experimental results can be obtained.
2008, 28(5): 374-384.   doi: 10.11728/cjss2008.05.374
Abstract(1825) [PDF 718KB](4)
Abstract:
Chang'E-1, the orbiter circling the moon 200km above the moon surface, is the first Chinese Lunar exploration satellite. The satellite was successfully launched on 24th October 2007.There are 8 kinds of scientific payloads onboard, including the stereo camera, the laser altimeter, the Sagnac-based interferometer image spectrometer, the Gamma ray spectrometer, the X-ray spectrometer, the microwave radiometer, the high energy particle detector, the solar wind plasma detector and a supporting payload data management system. Chang'E-1 opened her eyes to look at the moon and took the first batch of lunar pictures after her stereo camera was switched on in 20th November 2007.Henceforth all the instruments are successfully switched on one by one. After a period of parameter adjustment and initial check out, all scientific instruments are now in their normal operating phase.In this paper, the payloads and the initial observation results are introduced.
2014, 34(6): 867-871.   doi: 10.11728/cjss2014.06.867
Abstract(1187) [PDF 399KB](7)
Abstract:
The purpose of initial orbit determination, especially in the case of angles-only data for observation, is to obtain an initial estimate that is close enough to the true orbit to enable subsequent precision orbit determination processing to be successful. However, the classical angles-only initial orbit determination methods cannot deal with the observation data whose Earth-central angle is larger than 360°. In this paper, an improved double r-iteration initial orbit determination method to deal with the above case is presented to monitor geosynchronous Earth orbit objects for a spacebased surveillance system. Simulation results indicate that the improved double r-iteration method is feasible, and the accuracy of the obtained initial orbit meets the requirements of re-acquiring the object.
2009, 29(1): 54-58.   doi: 10.11728/cjss2009.01.054
Abstract(3141) [PDF 604KB](2)
Abstract:
This paper introduces several mainstream programmable logic devices used in space electronics equipment. In consideration of particular characteristics of space environment, special approaches should be used when using FPGA in space. Functional Triple Modular Redundancy (FTMR) approach in FPGA design has been introduced to protect design from the SEU (Single Event Upset) induced by radiation. Examples of FTRM are given to demonstrate the effects of this approach.
2018, 38(4): 444-451.   doi: 10.11728/cjss2018.04.444
Abstract(657) [PDF 2121KB](1)
Abstract:
Plasma sheet plays an important role in the coupling of solar wind and Earth magnetosphere, and the Cold-Dense Plasma Sheet (CDPS) is an important evidence of solar wind entry during the geomagnetic quiet time. However, there are handful statistical analyses using in situ observations to investigate the 2D profile of ion number density, temperature of plasma sheet and the CDPS occurrence rate in the xy plane of GSM coordinate. The Geotail data from 1996 to 2016 are used to fill that blank. The 2D profile of ion density, temperature of plasma sheet and the CDPS occurrence rate are plotted. A dawn-dusk asymmetry is seen in the 2D profile of ion density and in the cold-dense plasma sheet occurrence, but not seen in the 2D profile of ion temperature. The dawn-dusk asymmetry of ion density is more clear during the geomagnetic quiet time than that during the geomagnetic active time. Furthermore, the possible affect caused by the CDPS on the 2D profile of ion number density and temperature of the plasma sheet are investigated.
1995, 15(2): 137-142.   doi: 10.11728/cjss1995.02.137
Abstract(1936) [PDF 2573KB](7)
Abstract:
In this paper,results of ionospheric scintillation deduced from satellite TVsignals are presented,as well as properties of the TV signals.These experimental resulsts show that it is Fpossible to study ionospheric scintillation of C band signals using received TVsignals by a general TVreceiver with an additional processingcircuit.
2013, 33(6): 624-628.   doi: 10.11728/cjss2013.06.624
Abstract(1341) [PDF 482KB](2)
Abstract:
Ionosphere delay error is an unneglectable error source in the propagation of radio signal. The GPS authorized users utilize dual-frequency observations of dual-frequency receivers to determine the ionosphere delay in real time, so the measured results have a high precision. Compared to authorized users, most general users use the ionosphere model to correct the delay error when they utilize single-frequency receivers. Relative to dual-frequency observations, the correction effect by ionosphere model is not ideal. In this paper, dual-frequency observations are used to verify the Klobuchar model which chosen by GPS broadcast ephemeris has a widespread application in single-frequency receivers. Ten days' data of WUHN Observation Station has been picked up to analyze Klobuchar model, and the obtained results were consistent with previous researching results. Also, a new improvement method is proposed based on previous analysis. Since the variability of ionosphere has a close relationship with the Sun's activity intensity, and the sunspot relative number is a symbol reflecting the Sun's activity intensity, the new improvement method is realized by means of sunspot relative number to modify Klobuchar model. This improved method has been proved with a large scale promotion in the correction effect through experimental data. Relative to original model, the correction rate greater than 50% has upgraded from about 60% to 85% above, and that greater than 80% upgraded from 10% to 40% above. In practical application, users of single-frequency receivers can refer to this improvement method to correct Klobuchar model.
2009, 29(1): 7-9.   doi: 10.11728/cjss2009.01.007
Abstract(3893) [PDF 562KB](2)
Abstract:
Carbon fibre reinforced magnesium-based composites were fabricated by gas press infiltration method. Three kinds of magnesium alloys matrixes were employed. The fractographes of the composites were characterized by SEM, and the interfacial areas of C/Mg were characterized by TEM. The results showed that the reactions in the interfacial areas were affected by the content of Aluminum in the matrix. As the increasing content of Aluminum, the reactions became more intensive. Also, the interfacial bonding strength and microstructure were seriously influenced by the reactions. A weak-bonding interface was found in the C/c.p.Mg composite, however, the strong-bonding interfaces were found in both Cf/AZ31 and Cf/AZ91 composites.
1994, 14(4): 305-311.   doi: 10.11728/cjss1994.04.305
Abstract(2200) [PDF 376KB](5)
Abstract:
Asystematic comparison is made between the electron density profiles observed at four of the Chinese ionospheric stations during high solar activity periods and the International Reference ionosphere IRI-90.It is indicated that the bottomside values of IRI-90 are generally greater than measured ones. In detail, the IRI-90 predicted electron content values are more close to the measured ones in daytime than in nighttime, and more close at mid latitudes than at low latitudes.
2005, 25(4): 293-297.   doi: 10.11728/cjss2005.04.293
Abstract(1750) [PDF 1433KB](2)
Abstract:
2005, 25(2): 125-131.   doi: 10.11728/cjss2005.02.125
Abstract(1862) [PDF 2247KB](3)
Abstract:
2015, 35(5): 533-540.   doi: 10.11728/cjss2015.05.533
Abstract(827) [PDF 977KB](2)
Abstract:
A geomagnetic storm is a global disturbance in Earth's magnetic field, which is caused by various solar phenomenon. Dst index is the most widely used index which denotes the intensity of magnetic storm activity. The distributions of moderate geomagnetic storms (-100<Dst≤ -50nT) and intense geomagnetic storms (Dst≤ -100nT) and their causes in 1957-2008 are identified. Moreover, annual average number of geomagnetic storm in ascending phase, maximum phase, declining phase, and minimum phase of solar activity was analyzed according to different kinds of geomagnetic storms. It is found that the total number of geomagnetic storm in maximum phase year is greater than that in minimum phase year of the same solar activity, and there is close relation between the average number of Sun spots per year and the total number of geomagnetic storm. A dominant dual-peak distribution usually exists in the solar cycle variability of intense geomagnetic storm, but a dual-peak distribution of moderate geomagnetic storm exists and a trinal-peak distribution appears in intense geomagnetic storm. The presence of the extra peak might be attributing to a typical year compared to other rising phase years. On the other hand, another possibility is that 1999 could be an unusual year, with a low rate of intense magnetic storm. The magnetic storms mainly happen in equinox, and the number of magnetic storm is obviously changed with the increased Dst index.
2009, 29(1): 59-63.   doi: 10.11728/cjss2009.01.059
Abstract(3886) [PDF 578KB](6)
Abstract:
The research of Shijian-7 (SJ-7) solar array deployment on the ground was carried out using three methods, such as dynamic pressure simple formula, 3D-FLUENT simulation and generalized additive inertia method. For the first time the real-time coupling calculation was realized between multibody system dynamics and aerodynamics, and which is successfully applied on the research of the solar array. The results of the three different methods validate each other and get better precision than previous method. At the same time the simulation results are in accordance with the experiment results. The foregoing methods are applied on other solar array type which is being researched at present.
2017, 37(1): 8-18.   doi: 10.11728/cjss2017.01.008
Abstract(1256) [PDF 11420KB](5)
Abstract:
To develop a high performance MHD numerical simulation method is an important factor in research of numerical prediction of space weather. The upwind flux splitting scheme based on finite volume method has good ability to capture discontinuities. Steger-Warming and AUSM (Advection Upstream Splitting Method) schemes are two outstanding upwind flux splitting scheme, which are classified as FVS (Flux Vector Splitting) method. In this paper, these two schemes are applied to solve the Extended Generalized Lagrange Multiplier Magnetohydrodynamics (EGLM-MHD) equation with Galilean invariance. Results obtained from Orszag-Tang vortex and three-dimensional blastwave problem indicate that those two schemes are both robust and accurate. Particularly, AUSM scheme is superior to Steger-Warming scheme in divergence error control and computational speed.
2005, 25(6): 547-551.   doi: 10.11728/cjss2005.06.547
Abstract(2151) [PDF 1255KB](4)
Abstract:
A spacecraft that have been launched into orbit can fast close approach multiple non- coplane satellites of Walker Constellation without orbital maneuver by orbital design, since Walker Constellation has several special characteristics in construction, such as symmetry. To approach without orbital maneuver, the height of the spacecraft must be as same as that of the Constellation. Aimed at Walker Constellation, this paper presents a search method and a substitution method that on the base of the characteristic of Constellation. For a given Walker Constellation, both method can get a series of orbits with different orbit inclination. Typical orbits derived from the two methods are given. Each orbit can fast （in half of orbit period） close approach （zero distance for Walker） multiple （2 or more） non-coplane satellites of Walker Constellation.
2012, 32(2): 161-169.   doi: 10.11728/cjss2012.02.161
Abstract(2735) [PDF 989KB](0)
Abstract:
Based on the 3D global MHD numerical simulation data under extreme solar wind conditions, a dynamic 3D asymmetric magnetopause model under extreme solar wind conditions is developed. This magnetopause model parameters are fitted by the Levenberg-Marquart method and this magnetopause model has the ability to describe the saturation effects of the solar wind dynamic pressure Bd on the flaring of the magnetopause, the saturation effects of the interplanetary magnetic field (IMF) Bz on the subsolar standoff distance, the magnetopause indentation in the cusp region, the magnetopause asymmetry and the movement of magnetopause indentation center. On the basis of this model under extreme solar wind conditions, the subsolar point decreases with increasing Bd and increasing Bd causes the decrease of the magnetopause size but almost keeps the magnetopause shapes self-similar; with increasing southward (IMF) Bz, the subsolar point decreases slightly, the flaring of the magnetopause decreases and magnetopause indentation center moves towards lowlatitude. Through analysis of the solar storm on August 1, 2010, it is found that this magnetopause model can describe the global magnetopause location and shape under extreme solar wind conditions.
2009, 29(2): 213-221.   doi: 10.11728/cjss2009.02.213
Abstract(3599) [PDF 1070KB](5)
Abstract:
Based on the observing data of electro-magnetic field and other plasma parameters on DEMETER satellite of France, the anomalous variations in ion temperature Ti, ion density Ni, Very Low Frequency (VLF) magnetic spectral values and so on were analyzed before Yutian 7.2 earthquake in Xinjiang. The analysis on Ti shows that the abrupt abnormal signals above epicentral area occur frequently in a much wider space, so they are with lower reliability as seismic precursors. Using revisited orbit method to compare the shapes of the density of H+, it is found that all curves in a year are with consistent shape, but the peak amplitude in summer and autumn is 1 times of that in spring and winter. Compared the curves of Ni in 2008 with those in 2007 and 2006, apparent increases were exhibited at peak value regions in one month prior to Yutian earthquake with the amplitude rising to more than a magnitude relative to the other two years since February, and it continued to the earthquake occurrence. As for the magnetic spectrum data, orbits were selected in the distance of 2000\,km and single frequency (400 Hz) values were extracted and arranged to a time series according to their record date and common latitude scale (0~60°N). The results show that during 2 days before the earthquake, the spectrum values at 400 Hz increased approximately by an order of magnitude, reflecting an obvious electro-magnetic emission occurred in ionosphere before the earthquake. It is illustrated after processing the three components of ELF electric and magnetic field on March 20 by vector analysis that, some left-rotated polarization electro-magnetic signals existing at the observing period reflect that the variation of ion density in ionosphere was accompanied by the emission of ELF electro-magnetic signals. Summing up, the variation process of these ionospheric parameters is consistent to the coupling mechanism of earthquake preparation and ionosphere at present.
2014, 34(4): 441-448.   doi: 10.11728/cjss2014.04.441
Abstract(969) [PDF 2064KB](3)
Abstract:
Collision probability is an important criterion in collision warning of space objects. The accuracy of forecast covariance calculation directly affects the accuracy of the collision probability calculation. In the paper we compute two forms of statistical forecast covariance. One is to use precision numerical forecast model and the satellite precision orbit data to forecast for a specified time period, and make statistical calculation of forecast covariance of different time period as 1～ 7 days. The other is to use SGP4/SDP4 forecasting model and TLE data to forecast, and make the statistical calculation of forecast covariance of the forecast time period as 1～ 7 days. Then the forecast accuracy through two methods with the data elements affected by orbit change and without orbit change is analyzed. Taking the 2012 risk conjunction of the satellite as example, the collision warning accuracy affected by the covariance accuracy is analyzed. This covariance calculation can provide reference for actual collision warning works.
2006, 26(4): 268-276.   doi: 10.11728/cjss2006.04.268
Abstract(1976) [PDF 3379KB](0)
Abstract:
The navigation constellation design is involved in the optimization issues of many parameters. The goal of constellation design is to search a set of parameters and generate a navigation constellation using them. It is required that not only the optimal performance for the constellation needs to be the hest, but the cost of developing and maintaining the navigation satellite system is also low. Firstly, the indexes of evaluating constellation performance, algorithms of computing constellation availability and parameters of designing constellation are described in detail in this paper. There are three primary performance indexes examined, including the continued coverage, space distribution and redundancy. Secondly, as the navigation constellation design is a multi-objective optimization issue, the semi-analysis approach is presented simply in term of the practical engineering requirement. Only considering the central earth gravity, an ideal constellation can be designed from the aspect of geometry. The constellation parameters can be obtained synthetically and optimally in the case of meeting the constellation performance indexes. Therefore, four constellation schemes are generated optimally by using the approach. Finally, by analyzing the performance indexes and positioning simulation results respectively based on four schemes, it can be shown preliminarily that the semi-analysis approach and constellation schemes are feasible and rational.
2005, 25(6): 565-568.   doi: 10.11728/cjss2005.06.565
Abstract(1837) [PDF 1265KB](6)
Abstract:
Based on the bi-directional approach, the paper discusses the motion planning of freeflying dual-arm space robot systems. With the linear and angular momentum conversation, the state equation is established for the system control design. And then applying the Lyapunov method to the state equation, the control input equation of the manipulator joint angles controlling the vehicle attitude and the manipulator joint angles is obtained. Because no continuous trajectory from the start point to the end point in the state space can complete the desired task, the synthesized trajectory is gained to accomplish the desired task through the bi-directional approach. The advantage of the approach is to decrease the fuel consumption for controlling the vehicle attitude and prolong the available life-span of space robot systems. A planar dual-arm space robot system is simulated to verify the proposed approach.
2014, 34(2): 194-200.   doi: 10.11728/cjss2014.02.194
Abstract(857) [PDF 1633KB](3)
Abstract:
Due to compression and pyrogenation by shock wave, plasma sheath is formed around the surface of vehicle when hypersonic aerocrafts fly in near space. Plasma sheath can absorb and reflect electromagnetic wave radiated by the antenna on the vehicle. In order to analyze transmission property of plasma sheath, transfer matrix method is introduced. Based on the typical vehicle model and fundamentals of computational fluid dynamic, the Navier-Stokes equations are solved and electron density distribution in the plasma sheath is obtained. On the basis of propagation theory of electromagnetic wave and correlative characteristics of plasma sheath, the attenuation coefficient of electromagnetic wave in plasma sheath is diagnosed. On the other hand, propagation characteristics of electromagnetic signals which mainly include refection and transmission coefficients are analyzed. Analysis results show that good agreement is achieved among numerical results of transfer matrix method, theory analysis results and simulation results of FDTD (Finite Difference Time Domain). It is proved that the proposed method dramatically decreases computation complexity and is suitable for any kind of electron density distribution and thickness of plasma sheath.
2009, 29(1): 102-106.   doi: 10.11728/cjss2009.01.102
Abstract(2862) [PDF 502KB](2)
Abstract:
According to the principle of general relativity, in this paper the reference frame is chosen as the satellites, which levitate freely in the orbit under ideal circumstance, The movement of the test mass and the electrode cage of the electrostatically suspended accelerometer are discussed and the dynamics equation of test mass motion, inside the electrode cage is obtained. It is beared out, that the visible lacunan is in the similar expression offered by references [1],
[2]. The servo-control circuitry of the electrostatically suspended accelerometer is analyzed and the expressions of the electric damp coefficient, the closed loop natural angular frequency (i.e. the basic angular frequency of the accelerometer), the angular frequency dominated by the uncontrolled stiffness, such as the electrostatic negative stiffness, the acceleration from electrostatically suspending and the relatively displacement of the test mass etc are presented. It is put forward that the gain of the servo-control circuitry must be sufficient to provide the appropriate closed loop natural angular frequency. The expressions of the acceleration noise caused by the position noise are offered. It is proved, that the relatively displacement of the test mass is nearly naught in the frequency bandwidth of the suspension, when the gain of the servo-control circuitry is sufficient.
2012, 32(5): 693-703.   doi: 10.11728/cjss2012.05.693
Abstract(2132) [PDF 136KB](2)
Abstract:
Accompanying the flourishing developments of China’s manned spaceflight, space medicine has achieved great development during the past two years in China. In this paper, scientific research of space medicine and its application in China during 2010?2012 have been briefly introduced.
2013, 33(6): 659-663.   doi: 10.11728/cjss2013.06.659
Abstract(925) [PDF 979KB](1)
Abstract:
Deep dielectric charging and discharging effect is one of the key factors threatening the spacecraft safety. Besides the dielectric and its grounding configuration, deep dielectric discharging is also affected by the electron environment in space. The space dielectrics such as FR4, Teflon and Polyimide were tested in a simulated space radiation environment on ground, and their discharging currents and electrical field pulses were recorded. By analyzing frequency spectrum characteristics of the discharging transients and the effect of dielectric temperature, electron energy and electron beam intensity, a peak frequ