Subjects: Library Science，Information Science >> Indexing and Cataloging Subjects: Computer Science >> Natural Language Understanding and Machine Translation submitted time 2016-04-28
Abstract：[目的]拓展以物种为中心的生物多样性知识抽取框架，探索实现语义知识抽取方法。[方法]结合当前生物多样性抽取的主流研究，以物种为中心，设计包含多种实体及实体间关系的知识抽取框架，利用已有的众多专业数据库，设计并实现相应的识别方法。[结果]设计了以物种为核心的知识抽取框架，探索实现了多种实体及实体间关系的语义知识抽取方法，拓展了生物多样性领域抽取内容和思路。[局限]本研究实体识别的完整性和准确性受底层知识库影响较大，且实体间关系的类型局限于共现、上下位类、语法关系几类，还需进一步研究。[结论] 拓展了生物多样性领域抽取内容和思路，可有效支持后续的语义检索、科学计算。
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2016-04-27
Abstract：AstroCloud is a cyber-Infrastructure for Astronomy Research initiated by Chinese Virtual Observatory (China-VO) under funding support from NDRC (Na- tional Development and Reform commission) and CAS (Chinese Academy of Sci- ences). Tasks such as proposal submission, proposal peer-review, data archiving, data quality control, data release and open access, Cloud based data processing and analyz- ing, will be all supported on the platform. It will act as a full lifecycle management system for astronomical data and telescopes. Achievements from international Virtual Observatories and Cloud Computing are adopted heavily. In this paper, backgrounds of the project, key features of the system, and latest progresses are introduced.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2016-04-27
Abstract：AstroCloud is a cyber-Infrastructure for Astronomy Research initiated by Chinese Virtual Observatory (China-VO) under funding support from NDRC (National Development and Reform commission) and CAS (Chinese Academy of Sciences)1(Cui et al. 2014). To archive the astronomical data in China, we present the implementation of the astronomical data archiving system (ADAS). Data archiving and quality control are the infrastructure for the AstroCloud. Throughout the data of the entire life cy- cle, data archiving system standardized data, transferring data, logging observational data, archiving ambient data, And storing these data and metadata in database. Quality control covers the whole process and all aspects of data archiving.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： Solar energetic particles(SEPs) pose one of the most serious hazards to spacecraft systems and constrain human activities in space. Thus, it is of importance to forecast SEP events. Several theories and numerical models are applied to simulate SEP events. Each model makes some assumptions to simplify the complex acceleration and transportation processes within such events. In general, SEP will interact with ambient solar wind and background magnetic field during transportation. It is recognized that interplanetary transport effects must be taken into account at any analysis of SEP propagation. In the previous simulation, it always assumed Parker magnetic field and fixed solar wind speed as the input parameters. However, these assumptions are too simple when compared with the real conditions. In order to get better results, it is necessary to use more accurate background conditions. Recently, we change the fixed solar wind speed into spatial-dependent speed profile based on Parker's theory, and replace the Parker magnetic field with another Parker-like magnetic field based on in situ data at 1 AU. By solving the focused transport equation with simulation of time-backward stochastic processes method, our results show that:(1) Under fast solar wind speed assumption, it is clear that the omnidirectional flux decreases faster than that for the situation with slow solar wind speed in the decay phase. We suggest that it is due to the adiabatic cooling effect. Fast solar wind speed has a significant effect on the adiabatic cooling, which leads the SEPs to lose energy more quickly during transportation. However, slow solar wind speed has less impact on the time profiles of SEP flux and anisotropy. We also compare the time profiles of SEP event observed at different observatories and energies, the results remain the same as previous;(2) When applying in situ data of magnetic field observed by WIND during different Carrington Rotations, the omnidirectional flux time profiles vary greatly, and the main results are as followings:the peak flux appears to be delayed, multi-peak occur, anisotropy also has some differences.We think it results from the magnetic field polarity, which affects the pitch angle, and, furthermore, modulates the momentum. The characteristics are similar in solar minimum and solar maximum, while the peaks seem to be more when solar activity is active. We conclude that the real magnetic field polarity may exert a significant influence during the propagation of SEP. In the future, we will try to use the real-time background conditions which obtain from MHD models in our simulations, in order to make a thorough study of the SEP propagation.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： In this paper, airglow images of 630 nm emission are taken by an all sky imager in the Meridian Project Hainan Fuke Station (19.5癗, 109.2癊). The data processing including image enhancement, azimuth correction and image projection is performed to identify ionospheric plasma bubbles and to get clear image products. The optical observation of ionospheric plasma bubbles is the first of its kind in Hainan. With the optical measurements from September 2013 to May 2014, the spatial structure and its evolution, and the zonal drifts of plasma bubbles are analyzed. According to these observations, the plasma bubbles usually appear 1~2 hours after the sunset and last for 1~4 hours. September and October and February to April are the typical periods when the plasma bubbles appear. The shape of the plasma bubbles is just like stripes, which spread from north to south. Gradually the plasma bubbles maybe develop some bifurcations that look like plumage, and usually lean to the west. The size of the plasma bubbles in the east-west direction ranges from dozens to hundreds of kilometers. It is related to the seasonal variation. The west wall of the plasma bubbles is more steady than the east wall in the process of drifting. The typical velocity of east-west motion is in the range of 50~150 m穝-1. The analysis reveals the main optical observing characteristics of ionospheric plasma bubbles in Hainan. �2016, Science Press. All right reserved.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：基于RMAP协议对SpaceWire高速总线进行了架构设计与实现。首先给出了SpaceWire高速总线的整体设计;其次对SpaceWire编解码器中的DS编码进行了优化;然后根据RMAP协议的基础要求,设计了RMAP SpaceWire总线的工作流程与实现方法;最后通过仿真平台对该设计进行仿真测试。仿真测试表明:设计实现了RMAP SpaceWire高速总线的基础功能,数据链路传输速度可以达到79.84 Mb/s。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：首先,详细分析了调频连续波合成孔径雷达(FMCW SAR)机载试验系统,深入阐述了系统各部分的设计方法和主要原理,基于此系统进行首次校飞试验以验证系统性能;其次,深入分析了FMCW SAR回波信号特点和图像重建方法,揭示了其脉冲发射期间雷达的连续运动对回波信号的影响,定量地指出了其对图像重建的影响,并采用改进的距离多普勒算法对其补偿从而对场景进行聚焦;最后,通过实际航空校飞试验数据验证了系统分析设计和图像重建算法的有效性。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：针对数传、测距一体化的调制方式高斯最小频移键控复合伪码测距(Gaussian minimum shift keying+pseudo-noise,GMSK+PN)信号的信噪比估计,提出了一种精度较高、复杂度较低的快速算法。该算法采用层状结构分解的方式,将信号分解为若干信号单元,对每一个分解的信号单元进行功率分配计算或信噪比估计,最后快速准确地计算出整个信号的信噪比。信噪比在1~13dB之间时,估计误差小于0.5dB。利用Simulink仿真工具,验证了该算法的有效性。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：针对地月系L2点不同任务需求下的低耗能转移轨道设计问题,基于不变流形理论与混合优化技术,深入研究了不同月球借力约束与不同幅值Halo轨道的入轨点(简称HOI点)对转移轨道飞行时间与燃料消耗的影响,给出了HOI点选择策略。首先结合任务要求并考虑月球引力影响,在月球借力点施加不同约束条件,通过微分修正算法调整Halo轨道的稳定流形,设计月球到Halo轨道的转移轨道。采用遗传算法与微分修正算法相结合的混合优化策略,在同时考虑地球停泊轨道高度、倾角、升交点赤经与航迹角等多约束条件下,对燃料最优的地月转移轨道进行研究。最后,分析月球借力高度、借力方位角和不同HOI点对平动点转移轨道飞行时间与燃耗变化量的影响,对于考虑月球借力的地月平动点转移轨道设计与应用具有重要的参考价值。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： The magnetometer based on Giant Magneto-Impedance (GMI) effect becomes one of the hottest points on magnetometer research in recent years. Compared with other magnetometers, GMI magnetometer has the advantages of miniaturization, high sensitivity, quick response, high temperature stability and low power consumption. Based on the sensitive material of Fe-based nano-crystalline ribbon, a GMI probe and subsequent signal processing circuit have been designed and realized to compose a GMI magnetometer. Experimental results suggest that in the magnetic field ranging from-25000nT to 25000nT, the sensitivity is 0.176mV穘T-1, which attains the measurement requirement of a weak magnetic field. The magnetometer has advantages of small size and low power consumption so that could be used in space magnetic field measurement.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
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.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract：为了研究大面积等离子体片的分层特性,利用脉冲磁约束线形空心阴极放电装置,在150 Pa氦气中产生了持续时间为200μs、面积为60 cm×60 cm的大面积等离子体片。采用快帧法和旋转空心阴极法利用郎缪尔探针首次获得了等离子体片分层时厚度方向电子密度分布及其演化构成的二维分布图;基于获得的二维分布图,研究了分层等离子体片厚度方向电子密度的分布特征与磁场强度和放电电流的关系。实验发现,等离子体片分层时厚度方向电子密度呈现双峰曲线分布特征;当放电电流为2 A,磁场强度为1.5×10-2,2.25×10-2,3×10-2T时,双峰间距分别为0,3.2,8.4 mm;当磁场为3×10-2T,电流为1,2,3,4 A时,双峰间距分别为8.6,8.2,6.8,5 mm。结果表明:分层等离子体密度峰值间距随着磁场的增强和放电电流的降低而增大。
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： The planetary three-hour-range Kp index is widely used in space weather services. Due to the two weeks' time delay of the release of Kp index, the real-time estimation of the Kp index becomes essential for space weather forecasting organizations. In this paper, an improved algorithm for real-time Kp estimation on the basis of Takahashi's procedure was developed. The new algorithm improved the accuracy of Kp estimation by distinguishing the day-to-day variations of geomagnetic field's regular variation and taking account of both the diurnal and seasonal variations of magnetic disturbance. The statistical result shows that the Prediction Efficiency (PE) increased from 0.77 to 0.84 using Fredericksburg's data, from 0.88 to 0.92 using the nine stations network's data. Using the data from Beijing Ming Tombs observatory (BMT) from 2000 to 2006, the PE increased from 0.70 to 0.80 compared with the Takahashi procedure. The error of the estimations differs from universal time, season and the scale of magnetic disturbance. The RMS error reached maximum for Kp=7. Analysis of Kp using the SuperMAG indices indicated that the asymmetric distribution of Kp stations affects the Kp nowcast performance.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： Drawing the magnetic lines as streamlines is a general method of visualizing geomagnetic field. A key factor to evaluate the effect of the geomagnetic field visualization is whether the space distribution of geomagnetic field lines is consistent with that of magnetic field intensity, while the distribution of geomagnetic field lines is determined by seed point selection. The traditional algorithms that select seed points with uniform angles on magnetic meridian circles cannot objectively reflect the space distributions of magnetic field intensity. This paper proposes an algorithm of selecting seed points with equal line integral of magnetic field intensity. The algorithm is applied to draw the geomagnetic field lines with the data from T96 model and IGRF model. The redundant magnetic field lines existing in the result are removed. Statistical analysis and comparison between the space distribution of magnetic field lines and the geomagnetic field intensity reveals that this algorithm can effectively visualize the geomagnetic field.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： Using the magnetic field data from Cluster spacecraft and the Interplanetary Magnetic Field (IMF) data from ACE spacecraft, the effect of IMF By component (IMF |By|<10nT) on the Field-Aligned Current (FAC) occurrence rate and density at the Plasma Sheet Boundary Layer (PSBL) in the magnetotail is investigated. 1657 FAC cases from July to October in 2001 and 2004 were selected for analysis. We present that the IMF By component plays a very important role in controlling the occurrence rate and density of the FAC in the PSBL in the magnetotail. The FAC occurrence is higher (about 55.6%) when the IMF By is positive compared with that when the IMF By is negative. When the IMF |By| is more than 4nT, the occurrence rate of FAC is about 77.4%. The FAC occurrence in the magnetotail has an obvious positive correlation with the IMF |By|, and when the IMF By is positive, this correlation is better. The FAC density also has an obvious positive correlation with the IMF |By|, and when the IMF By is positive, this correlation is better. The above results show that the IMF By component has strong control on the occurrence and density of the FAC cases in the magnetotail, and that the change of FAC is closely associated with the duskward IMF (the IMF By is positive).
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： The characteristics of current high orbit GPS (Global Positioning System) signal are of poor availability and low positioning accuracy. Positioning of high Earth orbit satellites using GPS/Beidou combined system is studied. The visibility of navigation satellites and the Geometric Dilution of Precision (GDOP) are analyzed. Through simulation and analyzing, it is verified that the GPS/Beidou combined system has better performance than that of single GPS system. On one hand, the GPS/Beidou combined system can receive more satellites' signal than single GPS system. On the other hand, GDOP of the GPS/Beidou combined system is smaller than that of single GPS system. At the same time, the use of high-precision atomic clock in the satellite receiver can realize positioning of three satellites, and reduce the technology requirements of receiver.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： With the ever-increasing of space data, a reasonable data-arrangement is strongly required for high efficiency in data accessing and visualization. In this paper, basing on the characteristics of solar-wind data, a SDOG-R grid model is employed, which is radial independent division in the adaptive SDOG grid. For huge Sun-Earth space, it is divided into multi-resolution grids. The original data, which is output from a SIP-CESE solar wind model, are re-sampled, and put into the subdivided grids. The grid model is applied to both regular and irregular sampling data, and fully maintains the characteristics of original data to the best and encodes grids with an improved CDZ curve. Specific examples of data organization are given. The experiments prove that the grid model not only resolves the problem that grids are too dense at two poles and the spherical center, but also meets the need for higher resolution in radius than in latitude and longitude. Besides, 3D LOD spatial data model can not only provide multi-resolution data, but also significantly improve the large-scale mass data retrieval and access efficiency, and can support the organization and management of massive spatial data effectively.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： This paper introduces the structure and working principle of the Neutral Atom Imaging System-High （NAIS-H） which is in the MIT project. Based on the testing needs of the instrument， we have designed ground test equipment， including the circuit system and the host computer system. In this paper， we show the structure and working principle of the ground test for NAIS-H， and tell structure and java programming of the sub modules of the host computer system in detail， such as API communicating system， data analyzing system and data saving system. At last， we test the equipment， and the result shows the ground test system has good performance and achieves the design requirement.
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： For the small satellites formation flying， the distance between satellites must be determined and an adequate inter-satellites communication medium must be used to transmit the science data. In order to minimize device complexity， this paper studied a system capable of simultaneously transmitting high rate telecommunication and ranging. through simulations by Simulink in different ranging modulation index， obtained the bit error rate of telecommunication data. By analyzing the characteristics of GMSK+PN signal， an effective demodulation scheme for GMSK+PN is developed by this paper.
Peer Review Status:Awaiting Review
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