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A new stochastic model considering satellite clock interpolation errors in precise point positioning
Shengli Wang Fanlin Yang Wang Gao Lizi Yan Yulong Ge 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(5):1332-1341
Precise clock products are typically interpolated based on the sampling interval of the observational data when they are used for in precise point positioning. However, due to the occurrence of white noise in atomic clocks, a residual component of such noise will inevitable reside within the observations when clock errors are interpolated, and such noise will affect the resolution of the positioning results. In this paper, which is based on a twenty-one-week analysis of the atomic clock noise characteristics of numerous satellites, a new stochastic observation model that considers satellite clock interpolation errors is proposed. First, the systematic error of each satellite in the IGR clock product was extracted using a wavelet de-noising method to obtain the empirical characteristics of atomic clock noise within each clock product. Then, based on those empirical characteristics, a stochastic observation model was structured that considered the satellite clock interpolation errors. Subsequently, the IGR and IGS clock products at different time intervals were used for experimental validation. A verification using 179 stations worldwide from the IGS showed that, compared with the conventional model, the convergence times using the stochastic model proposed in this study were respectively shortened by 4.8% and 4.0% when the IGR and IGS 300-s-interval clock products were used and by 19.1% and 19.4% when the 900-s-interval clock products were used. Furthermore, the disturbances during the initial phase of the calculation were also effectively improved. 相似文献
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Guanglin Ma Lixin Guo Jutao Yang Libin Lv Jing Chen Tong Xu Shuji Hao Jian Wu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(7):2126-2131
Beat wave (BW) high frequency (HF) ionospheric heating experiments were conducted to generate very low frequency (VLF) waves. The VLF waves were registered with a VLF receiver located ~15?km east of the European Incoherent Scatter (EISCAT) heating facility in Tromsø, Norway. A fluxgate magnetometer was used to monitor auroral electrojet current, and ionospheric conditions were measured using a Dynasonde. Correlation coefficients between VLF amplitudes and the deviation of geomagnetic north–south components were calculated. Experimental results show that strong and positive correlation exists the majority of the time, but sometimes no correlation or even a negative correlation occurred. This is consistent with similar past experiments that took place with exclusively AM generation. These results therefore support the conclusion that BW generation of VLF waves is no different than with AM, likely occurring in the D or lower E ionospheric region. 相似文献
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本文基于数值模拟的方法,研究了四种不同结构 (A型、B型、C型、D型)的总压探针在不同近壁距离条件下对流场及自身总压测量值造成的影响,并将数值模拟结果与文献实验结果对比。结果表明:相对近壁距离c/d越小,造成总压探针头部气流偏转角误差越大,总压探针的测量误差越大,总压损失系数最大值小于1%;当c/d>3,总压损失系数趋近于0,说明近壁距离大于3倍探针外径时临壁效应消失;在同一工况下,四种结构的总压探针测量值受到临壁效应的影响依次增大;被测流场流动均匀性减小,靠近总压探针支杆后方速度均匀度最小。 相似文献
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似曾相识的大学合并Acquainted merger of universities通常对芬兰教育的了解,多半都停留在"世界第一教育"的光辉业绩上:一个只有520万人口的国家,却拥有20所大学和19所技术大学,教育投资占国内生产总值的6.2%;芬兰中学生在"国际学生评量计划"中长期领先;它的高等教育,几乎被每一届世界经 相似文献
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