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北斗星基增强(BDSBAS)系统播发格网电离层改正数和格网电离层完好性参数GIVE,用以提升GNSS系统的服务精度并实现区域电离层活动完好性监视,以满足精密进近(GLS PA)需求.本文在实现BDSBAS格网电离层粗差剔除与改正数计算的基础上,提出了一种电离层完好性参数GIVE的优化方法,进而评估了BDSBAS格网电离层的应用精度.BDSBA S格网电离层格网点延迟估计采用平面拟合算法计算,异常数据剔除采用稳健的中值容错算法,GIVE的估计考虑了电离层残差分布的偏度与峰度统计特性,能够实现对电离层异常活动的及时响应.2020年1月实测数据分析结果表明,BDSBAS格网电离层修正精度(RMSE)为2~3 TECU,改正百分比达到75% ~79%,GIVE包络率优于99.9%.修正格网电离层后可提升GPS定位精度20% ~40%. 相似文献
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西天山阿吾拉勒地区A型流纹斑岩的初步研究 总被引:1,自引:0,他引:1
新疆阿吾拉勒山是中亚造山带的重要组成部分。通过对区内火山岩的主量元素和微量元素地球化学研究,在群吉萨伊-塔尔得套一带下二叠统乌朗组中厘定出了一套铝质A型流纹斑岩。群吉萨伊和塔尔得套的流纹斑岩具有富硅(SiO2≥69.9%)和富碱(Na2O+K2O≥7.06%)的特征。其中,塔尔得套流纹斑岩的总碱含量低于群吉萨伊流纹斑岩,但其K2O含量则明显高于后者,属于高钾火山岩。二者均具有明显的Ba、Sr、Eu和Ti亏损,稀土总量在90.7×10-6~264×10-6之间。主量元素和微量元素特征显示,群吉萨伊和塔尔得套的A型流纹斑岩的源区均与硬质砂岩相似,属于A2型花岗岩,同时具有较高的锆饱和温度(TZr约900°C),其成因可能与后俯冲阶段的岩石圈拆沉过程有关。 相似文献
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对比研究了国内外风廓线雷达产品天线系统和子阵的类型,设计了一款5波束有限相扫相控阵微带天线子阵。此天线系统由21个相同的正方形子阵组成,每个子阵包含16个阵元,4×4的正方形对称划分,每个阵元采用东西向、南北向2点同轴背馈馈电,子阵内双方向分别设计了等幅等相馈电网络,进而实现了东西向和南北向的水平极化。天线子阵各端口驻波小于1.2,提高了天线探测灵敏度,缩小了相控阵天线阵面面积,减轻了天线阵重量。结合子阵划分,优化了相控阵天线系统泰勒加权。天线具有两维步进电扫功能,在空域形成5个波束的探测。应用在TWP3型边界层风廓线雷达上,雷达探测高度大于5km。 相似文献
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2005年起发射的GPS Block IIR-M卫星在L2频率上新增了L2C民用信号,2010年起发射的Block IIF卫星新增了L5频率及L5I、L5Q两种民用信号。为此,GPS民用广播星历在原有时间群延迟(TGD)参数的基础上,新增了ISC_(C/A)、ISC_(L2C)、ISC_(L5I)及ISC_(L5Q)4种ISC(inter-signal correction)参数,以服务GPS实时导航定位用户。本文给出了ISC参数在GPS单/双频定位中的改正方法、利用不同机构提供的后处理差分码偏差(DCB)产品评估了ISC参数的实际精度、研究了ISC参数对GPS民用导航定位精度的影响。在明确TGD、ISC和DCB 3类参数之间区别与联系的基础上,本文研究表明:GPS广播的ISC_(C/A)参数精度可达0.2ns,TGD、ISCL2C及ISCL5Q参数精度可达0.5ns;以2014年连续11d全球12个MGEX(multi-GNSS experiment)站为例,经由ISC参数改正后,GPS L2C单频标准单点定位(SPP)的位置解精度提高了30.6%,L1C/A+L2C双频SPP的位置解精度提高了12.2%,该精度与L1P(Y)+L2P(Y)消电离层组合SPP的位置解精度相当。 相似文献
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Estimation and analysis of Galileo differential code biases 总被引:1,自引:0,他引:1
Min Li Yunbin Yuan Ningbo Wang Zishen Li Ying Li Xingliang Huo 《Journal of Geodesy》2017,91(3):279-293
When sensing the Earth’s ionosphere using dual-frequency pseudorange observations of global navigation satellite systems (GNSS), the satellite and receiver differential code biases (DCBs) account for one of the main sources of error. For the Galileo system, limited knowledge is available about the determination and characteristic analysis of the satellite and receiver DCBs. To better understand the characteristics of satellite and receiver DCBs of Galileo, the IGGDCB (IGG, Institute of Geodesy and Geophysics, Wuhan, China) method is extended to estimate the satellite and receiver DCBs of Galileo, with the combined use of GPS and Galileo observations. The experimental data were collected from the Multi-GNSS Experiment network, covering the period of 2013–2015. The stability of both Galileo satellite and receiver DCBs over a time period of 36 months was thereby analyzed for the current state of the Galileo system. Good agreement of Galileo satellite DCBs is found between the IGGDCB-based DCB estimates and those from the German Aerospace Center (DLR), at the level of 0.22 ns. Moreover, high-level stability of the Galileo satellite DCB estimates is obtained over the selected time span (less than 0.25 ns in terms of standard deviation) by both IGGDCB and DLR algorithms. The Galileo receiver DCB estimates are also relatively stable for the case in which the receiver hardware device stays unchanged. It can also be concluded that the receiver DCB estimates are rather sensitive to the change of the firmware version and that the receiver antenna type has no great impact on receiver DCBs. 相似文献
49.
Reference crop evapotranspiration(ET 0) is a key parameter to calculate crop water requirements.In the paper,ET 0 during 1960-2005 was calculated with FAO-56 PM in eastern agricultural areas of Qinghai,China.Then the sensitivity coefficients of ET 0 to meteorological variables were estimated through the nondimensional partial derivative in FAO-56 PM.Results show that the mean annual ET 0 of the whole area is 904 mm,and ET 0 portrays a very significant decrease during the 46 years.In spatial,ET 0 decreases from southeast to northwest,firstly increases then decreases from southwest to northeast.Through sensitivity analysis,in spring the most sensitive variable is relative humidity,while in summer is temperature.The temperature,sunshine duration and wind speed sensitivity coefficients(S(TA),S(n),S(u)) are higher in middle areas as opposed to surrounding areas,while the relative humidity sensitivity coefficient(S(RH)) has an opposite distribution rule. 相似文献
50.
Precise structural identification of phospholipids in the microalga Nitzschia closterium has been established using ultra performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (UPLC-ESI-Q-TOF-MS) for direct analysis of total lipid extracts.Mass spectrometry was performed in reflective time-of-flight using electron spraying ionization in negative mode.Phospholipid molecular species identification was based on the characteristic product ions and neutral loss yie... 相似文献