2017 Vol. 37, No. 4

Display Method:
哈勃常数之争或改写宇宙学定律
2017, 37(4): 369-369.
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Chandra等可能发现距离黑洞最近恒星
2017, 37(4): 369-369.
Abstract(238) PDF 359KB(1494)
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Swarm团队公布地球岩石圈磁场详细地图
2017, 37(4): 370-370.
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VAP发现内辐射带相对论电子数量低于预期
2017, 37(4): 370-370.
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俄美研究Venera-D任务科学目标
2017, 37(4): 371-371.
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Rosetta对Aswan悬崖崩塌的观测揭示彗星原始冰冻内部
2017, 37(4): 371-371.
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Sentinel-2B卫星发射成功
2017, 37(4): 371-371.
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NASA报道GRACE卫星在轨15年的重要科学发现
2017, 37(4): 372-372.
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首枚重复使用的猎鹰火箭发射成功
2017, 37(4): 372-372.
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俄罗斯《2025年前ROSCOSMOS发展战略》
2017, 37(4): 374-375.
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NASA公开载人火星探索计划
2017, 37(4): 376-376.
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NASA“天体物理探测器任务概念研究”调研报告
2017, 37(4): 377-377.
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中国空间科学任务概念建议征集完成
2017, 37(4): 378-378.
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NASA 2017预算授权法案对推动中国空间科学发展的启示
2017, 37(4): 379-380.
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Statistical Comparison of Magnetic Clouds with Non-magnetic Clouds in Interplanetary Coronal Mass Ejections for Solar Cycle 24
LOU Fei, YE Yudong
2017, 37(4): 381-394. doi: 10.11728/cjss2017.04.381
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Interplanetary Coronal Massive Ejections (ICME) are major drivers of geo-magnetic storms and have great influence on the space weather environment. ICMEs can be divided into two parts:Magnetic Clouds (MC) and non-Magnetic Clouds (non-MC). MCs have large and smooth rotation in the magnetic fields' angle compared to non-MC, and they can interact with the Earth's magnetosphere more easily and cause severe space weather events. To make an insight into the on-going Solar Cycle (Solar Cycle 24) and its MCs and non-MCs' characteristic and space weather effect, a statistical research is made on 168 ICMEs during 2008-2015 using the data from observation at 1AU. There are 68 MCs and the MC rate of ICME is 40.48%. The MCs and non-MCs' plasma parameters and their effect on the space weather, relationship with the solar activities, comparison with each other, and different appearance in Solar Cycle 23, 24 were analyzed. In Solar Cycle 24, the geo-magnetic storms caused by MCs are usually stronger than those caused by non-MC. The south component of magnetic field is of great importance to cause the storms. MC occurrence has a good correlation with the Sunspot Number (SSN), while non-MC and ICME' correlation coefficient with SSN is smaller, and the number of MC shows different distributions during different solar cycle phases. MCs' magnetic field and south component of magnetic field are stronger than those of non-MC on total, but the difference between their temperature and proton density is very small. The geo-magnetic effect of MCs in Solar Cycle 24 are weaker than those in Solar Cycle 23. This is because of that the maximum south component of magnetic field, the propagation speed and the proton temperature of magnetic clouds in Solar Cycle 24 are smaller.
Systemic Quantitative Evaluation of the Radiation Belt AP9 Model in SAA Region
MA Jie, FANG Hanxian, WANG Shijin, WANG Qixi, WENG Libin, JING Wenqi, GUO Zhe
2017, 37(4): 395-402. doi: 10.11728/cjss2017.04.395
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The evaluation of the radiation belt AP9 model is not systematic enough. The high, medium and low solar activity level is classified in view of the F10.7 index. The corresponding data of the proton flux between 140 and 500MeV observed by NOAA-15 are chosen as the reference data. The objective region is the South Atlantic Anomaly (SAA) region. The evaluation criteria conclude the goodness of boundary fitness and the magnitude difference between model and observation. By contrasting with the current applied AP8 model and reference data under high, medium and low solar activity level, the new radiation belts proton model AP9 is systematically and quantitatively evaluated. The results show that both the AP8 and AP9 model can reconstruct the SAA region. However, the outline of SAA region reconstructed by AP8 is more consistent with the observation than that of AP9. On the whole, the AP8 and AP9 results are higher than the observations, and AP8 results are closer to the observations than AP9 results. The lower the solar activity level is, the smaller the difference between AP9 model results and observations is.
Effects of Background Conditions on Lower Ionosphere Pre-heating Amplitude-modulation
YANG Ding, FANG Hanxian, WANG Sicheng
2017, 37(4): 403-413. doi: 10.11728/cjss2017.04.403
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Based on the energy conservation equation and electron continuity equation, the Pre-heating Amplitude-Modulated Theoretical Model (PAMTM) of ionospheric current modulated by powerful HF radio waves, is constructed. The oscillations process of ionospheric density in pre-heating period and current in modulation period are analyzed. Moreover, the effects of different background condition on radiation strength of electromagnetic wave in Extremely Low Frequency/Very Low Frequency (ELF/VLF) band are studied in details by use of PAMTM. The results indicate that PAMTM is more effective in the daytime than in the nighttime. It has the largest strength increment in spring and the intensity of pre-heating amplitude at solar maximum is bigger than that of solar minimum. Its intensity increment amplitude at low latitude is stronger than that of middle latitude. Under certain heating conditions (fERP=200MW, fELF/VLF=1kHz), the effect of the PAMTM is the best when the pre-heating time is 10s considering energy loss, and ELF/VLF radiation levels can be improved by 10.00dB.
Statistical Analysis of GPS Scintillation and TEC Depletion in Temporal and Spatial Distributions over South China
HUANG Rongze, XU Jie, DENG Kun, HUANG Jiang, DENG Baichang, QUAN Hongjun
2017, 37(4): 414-423. doi: 10.11728/cjss2017.04.414
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The temporal and spatial distribution of scintillations accompanied with Total Electron Content (TEC) depletions, scintillations with no TEC depletions, and TEC depletions with no scintillations are discussed. The data of ionospheric scintillation and TEC from January 2011 to December 2012, and from January 2015 to December 2015 are observed by the monitor setting at Shenzhen GPS station. The results show that these three types of events occurred mainly in spring and autumn. These three types of events occurred mainly from 19°N to 23°N, 21°N to 24°N and 24°N to 26°N, respectively. In addition, these three types of events occurred mainly from 20:00LT to 22:00LT, 21:00LT to 23:00LT, 22:30LT to 23:30LT, respectively. The temporal and spatial distributions of these three types of events are responsible for the evolution process of equatorial plasma irregularity over South China.
Observations of Sodium Layer over Beijing and Haikou in July 2012
ZHANG Tiemin, WANG Jihong, WANG Linmao, CHEN Xueming, WU Jianqing, ZOU Xu, PENG Hongyan
2017, 37(4): 424-431. doi: 10.11728/cjss2017.04.424
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The observations were conducted by lidar over Haikou (20°N, 110°E) and Beijing (40°N, 116°E) in July 2012. The basic characteristics of the sodium layer density at a low-latitude and mid-latitude location are analyzed by the observations. The double sodium layer events and sporadic layer were observed over Beijing and Haikou. A Nd:YAG laser and a pumped dye laser are used to generate the probing beam. The wavelength of the dye laser is set to be 589nm by a sodium fluorescence cell. The energy and divergence of the beam are set about 45mJ and 1mrad, respectively. The backscattered fluorescence photons from the sodium layer are collected by a telescope with a primary mirror which diameter is equal to 1000mm. There are 9 events of Sporadic Sodium Layer (SSL) and 1 event of Double Sodium Layer (DSL) occurred in Haikou, and 1 event of SSL and 4 events of DSL occurred in Beijing. The variety and distribution of the sodium density over Beijing and Haikou during the night of July 1, 2012 are compared. A DSL structure was observed and it had lasted 120min during the night of July 1, 2012 over Haikou, but no DSL structure occurred over Beijing.
Quasi-16-day Planetary Waves during Sudden Stratospheric Warming Event
ZHU Lu, JIANG Guoying, XU Jiyao, CHEN Jinsong, HU Lianhuan, NING Baiqi
2017, 37(4): 432-441. doi: 10.11728/cjss2017.04.432
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A minor Sudden Stratospheric Warming (SSW) event occurred in the early and middle January of 2014. The amplitude of increasing temperature was about 25K, and the zonal eastward wind became weaker and shifted its direction until the early February. The Planetary Waves(PW)} play an important role in SSW events. Using the wind data detected by 5 meteor radars at low and middle latitude of northern hemisphere near 120°E, the PWs during this minor SSW event are studied. Results show that the enhanced quasi-16-day PW is found at Mesosphere and Lower Thermosphere (MLT) region. The enhancement of quasi-16-day waves was prior to the warming, and the quasi-16-day PW had mostly the strongest amplitude when the polar temperature reached its peak. This demonstrates the coupling between PW of low and middle latitude MLT region and SSW. Furthermore, using the reanalysis data from the European Center for Medium-range Weather Forecasts (ECMWF), the wave coupling between stratosphere and mesosphere is investigated. The band pass filtering result of the stratospheric temperature shows that quasi-16-day PW propagated from lower latitude to the pole, meanwhile the zero-wind line moved from low latitude to high latitude, The results indicate a dynamical connection between the 16-day PWs and SSW.
Cut-off of Alfvén Waves in Weakly Ionized Near-Earth Atmosphere
LIU Mingwei, ZHANG Yutao, LI Yanhua
2017, 37(4): 442-447. doi: 10.11728/cjss2017.04.442
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Propagation of magnetic perturbation in the near-Earth atmosphere is associated with many applications, such as analysis of earthquake signals received by satellites and magnetic anomaly detection. These propagation properties are thought to be similar with those of electromagnetic waves in free space. However, some literatures show that magnetic perturbation signals also can penetrate into near-earth atmosphere by means of Alfvén waves, considering the effect of geomagnetic field. In this paper, the propagation properties of magnetic perturbation signal in the near-earth atmosphere, by using a total-current and two-fluid model, are studied. The results show that the propagation models of magnetic perturbation signal depend on the neutral-ion collision frequency, the perturbation frequency, the coefficient of magnetic diffusion and the ionization fraction. Alfvén Waves cannot exist in the near-earth atmosphere because of neutral-ion collisions. When the frequency of magnetic perturbation is smaller than 0.001Hz, the magnetic perturbation signals decay according to the skin effect, which increases as the height to the ground decreases. When the frequency of magnetic perturbation is larger than 0.001Hz, the propagation of magnetic perturbation signal in the near-earth atmosphere is similar to that of electromagnetic wave in vacuum.
Confidence Level of Collision Probability for Space Debris with Chebyshev Inequality
SHEN Dan, YANG Xu, WU Xiangbin, LIU Jing
2017, 37(4): 448-454. doi: 10.11728/cjss2017.04.448
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A growing space debris population which results to the high collision risk increasingly causes the requirement of research in a congested space environment. It's necessary to make the collision assessment for effectively avoiding collisions. The probability of collision is the main criterion for the collision assessment and warning of satellite against space debris, and is the main reference for the decision of the avoidance maneuver of the satellite. However, the collision probability is not accurate because of the parameter errors which are used to calculate the collision probability, so it is difficult to make decision. Hence, how to evaluate the reliability of the collision probability is the pressing problem. In this paper, a method for calculating the confidence level of collision probability above the threshold value of 10-4 is proposed. By using the propagation of error, the standard deviation of collision probability is calculated, and combining with the one-sided Chebyshev inequality, the confidence level is obtained. The results are also analyzed with practical cases.
Influence of Chip Size on Bubble Dynamic Behavior in Microgravity
QI Baojin, WEI Jinjia, WANG Xueli, ZHAO Jianfu
2017, 37(4): 455-467. doi: 10.11728/cjss2017.04.455
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In order to study the influence of chip size on bubble dynamic behavior in microgravity, the factor of chip size on bubble dynamics under various heat fluxes has been studied by comparison experiments. Typical isolated bubble boiling maintains on both small and large size chips in low heat flux, and the growth and coalescence rates of bubbles are relatively slow. The volume of bubble on large size chip is about 3.4 times that of the bubble on small size chip. The bubble departure could only be observed on the large chip during the experiment. Fully developed nucleate boiling are sustained in the case of moderate heat flux, the coalescence and departure frequency of bubbles is much higher than that in low heat flux, especially on large size chip. Bubbles detach more frequently on large size chip than that on small size chip. Moreover, the wake effect caused by bubble rising reduces the departure diameter of subsequent bubbles, so the formation of dry portions is effectively suppressed. For the high heat flux, obvious film boiling presents on the small size chip and the deterioration of heat transfer is observed. However, stable nucleate boiling still maintains on large size chip in the high heat flux, only the bubbles coalesce and detach more frequently. Therefore, increasing the chip size can effectively promote the bubble departure and improve critical heat flux. Film boiling is also observed as the heat flux on larger size chip is increased beyond the critical heat flux, but the heating surface could not be completely covered by the bubble, just sliding slowly on the slip, which can reduce the rising rate of temperature on chip effectively.
Exclusion of Spacecraft Internal Multipath among Pseudorange Variation Reasons
GAO Shuai, XU Yun, YANG Huafeng, LIU Jiancheng
2017, 37(4): 476-483. doi: 10.11728/cjss2017.04.476
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For the code pseudorange variations in the satellite's visible range, ranging bias variation of navigation signal is studied from the point of view of signal quality monitoring, and it's consistency with the code pseudorange variations is confirmed. By using of large antenna to track COMPASS satellite, multiple high CNR B1 signal are collected by two data acquisition platforms. The collected data are processed separately according to ranging bias estimation method based on reference waveform, and ranging biases in different elevation angles are obtained. For one elevation angle, when filter bandwidth is much larger than signal bandwidth, the ranging biases are same for the two data acquisition platforms with different sampling rate and down converter. The ranging biases are both related with correlator spacing and filter bandwidth. However, the difference of ranging bias can be omitted when filter bandwidth is larger than 15MHz. Furthermore, ranging biases of different elevation angle is compared, and the results show that the difference of ranging biases is tiny. Therefore, signal quality changes in satellite's visible range induced by spacecraft internal multipath is excluded from pseudorange variations.
Calibration test of neutral atom image system with high energetic particles for the MIT mission (in Chinese)
LU Li, YU Qinglong, ZHANG Huanxin, JING Tao, YANG Chuibai
2017, 37(4): 484-489. doi: 10.11728/cjss2017.04.484
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The Neutral Atom Image System with High energetic particles (NAIS-H) is developed for a Chinese mission of Magnetosphere Ionosphere and Thermosphere (MIT) in order to obtain the global map of the plasma distribution with high temporal-spatial resolution. The calibration of NAIS-H is an important technical task in the development, which is the fundamental basis of data analysis and inversions. The calibration curves show a good linear feature of the detector. Simulating calibration shows the linear feature and the energy response function of the model. But the instrument has a lot of sensors, and some of them may have the parameter errors that should be amended with the test results by proton accelerator.
Physical Layer Design of Microwave Communication Link for Quantum Science Experiment Satellite
WANG Zhugang, XIONG Weiming, QU Chenyang, CHEN Qiaoyan
2017, 37(4): 490-498. doi: 10.11728/cjss2017.04.490
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In order to ensure quantum science experiments can be developed smoothly, a high data rate two-way link for Space-Ground microwave communication must be established. By following the study on Consultative Committee for Space Data Systems (CCSDS) and taking into account the scientific requirements of microwave communication link for quantum science experiment satellite, the physical layer hardware architecture and modulation/demodulation algorithm of microwave communication link for the satellite are presented. The uplink modulation type of the microwave communication link is SRRC-OQPSK, which is accordance with CCSDS spectrum standard. The specification of uplink data rate is 1.024Mbit·s-1. The downlink modulation type of the microwave communication link is SRRC-OQPSK/GMSK, and the data rate is 4Mbit·s-1. By compatible tests with several ground stations, it is found that the sensitivity of carrier acquisition is superior to -100dBm, and AGC (Automatic Gain Control) ability is greater than 43dB. Moreover, the bit error rate of actual transmission is superior to 1×10-9 as the received signal level is equal to -96dBm. The in-orbit verification indicates that the physical layer design scheme of microwave communication link meets the requirements of space quantum science experiments.
L2 Back-stepping Control Based on Disturbance Observer for Space Robot under Dead-zone Effect
DAI Qiaolian, CHEN Li
2017, 37(4): 499-506. doi: 10.11728/cjss2017.04.499
Abstract(694) PDF 859KB(3250)
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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.
他在天舟的实验事关人类太空生育可能性干细胞资料纪家葵课题组实验——清华大学医学教授纪家葵专访
2017, 37(4): 507-507.
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空间天气学国家重点实验室
2017, 37(4): 508-509.
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