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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(4):1196-1209
The overlapping-frequency signals from different GNSS constellations are interoperable and can be integrated as one constellation in multi-GNSS positioning when inter-system bias (ISB) is properly disposed. The look-up table method for ISB calibration can enhance the model strength, maximize the number of integer-estimable ambiguities, and thus is preferred. However, the characteristics and magnitudes of the receiver code ISB and phase fractional ISB (F-ISB) are not well known and the wrong values of the biases can seriously degrade the positioning results. In this contribution, we first estimate the between-receiver code ISB and phase F-ISB of hundreds of the baselines up to around 25km in the European Permanent GNSS Network (EPN) and the Multi-GNSS Experiment (MGEX) for the overlapping frequencies L1-E1 (L1), L5-E5a (L5) and E5b-B2b (L7). The data collected from 1st January 2016 to 1st January 2019. Second, the receiver-type and firmware-version combinations for the receivers of Trimble, Leica, Javad, Septentrio and NovAtel are carefully classified. Results show that the Septentrio receivers have consistent code and phase ISB values for the three overlapping frequencies i.e. only one value for each frequency and no receivers are different. The Leica, Trimble and Javad receivers have two or more ISB values for at least one of the three frequencies. A few receivers with biases to the groups are also found and listed. Third, the code ISB and phase F-ISB of the groups are adjusted by the least-squares method. The root mean square errors (RMSE) of the least square adjustment are 0.240 m, 0.250 m and 0.200 m for code of L1, L5 and L7 frequencies, respectively, and are 0.0009 m, 0.0015 m and 0.0031 m for phase of L1, L5 and L7 frequencies, respectively. Finally, the effects of code ISB errors on code positing are investigated with the zero-baseline MAT1_MATZ. The distance root mean square error (DRMS) of L1-E1 code positioning can be reduced by 48.2% with 5 GPS and Galileo satellites and the DRMS degrades quickly when the code ISB error is larger. 相似文献
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本文用信号分解和叠加的理论及方法,推导出一种适用于分析运算放大电路反馈特性的“分解方框图”,并通过实例介绍了相量图分析法。 相似文献
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介绍了DPA—Switch芯片的外部引脚、内部电路及功能模块;讲解了同步整流电路的基本工作原理。根据DPA—Switch的特性给出了同步整流开关电源的设计方法和具体的设计电路,并对外围电路的设计进行了分析,最后给出了测试结果及设计注意事项。 相似文献
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对目标单位是市和区县级工商行政管理局或分局的工商行政管理信息系统的特点及功能给予介绍。该系统友好的用户界面、丰富强大的功能,安全、快捷、方便的操作,受到了用户的好评。 相似文献
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In order to investigate the yielding behavior of the newly developed Ni 3 Al-based intermetallic alloy IC10, yield stresses have been measured in tension and compression with different orientations. The specimens were cut from a sheet with different angles inclined from the solidification direction. The inclined angles were taken to be 0 , 22.5 , 45 , 67.5 and 90 . All experiments were conducted at room temperature except for orientation 0 , whose deformation temperatures ranged from 298 to 1273 K. Experimental results show that the yield strength of alloy IC10 has the anomalous behavior which has been observed for other Ll 2 -long-range ordered intermetallic alloys, but it is less pronounced. The abnormalities show the following characteristics: (i) the yield strength increases as the temperature is raised below the peak temperature, (ii) yield strength anisotropy, (iii) tension/compression asymmetry. Compared to Ni 3 Al single crystals, the polycrystalline exhibits some different yielding behaviors which may be due to the high volume fraction of c phase. 相似文献
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《中国航空学报》2021,34(1):438-448
Ni3Al-based superalloy IC10 is widely used in high temperature components of aero-engines because of its superior mechanical properties. In this paper, the creep feed grinding properties of IC10 were investigated experimentally. The effects of grinding parameters on the grinding forces and temperature were examined. Moreover, the influences of surface roughness and hardening on the high-cycle fatigue life of IC10 specimens were studied. To control the creep feed grinding parameters and enhance the fatigue life of IC10 components, the experimental results were summarized to offer a useful reference point. It is concluded that, the grinding depth is the most important factor which influencing the grinding forces and temperature; the surface roughness is the main and unfavorable factor on the fatigue life of IC10, while the surface hardening has a positive influence on the fatigue life; to obtain a better surface quality and improve the fatigue life of IC 10, the recommended grinding parameter domain involves wheel speed ∈ [15, 20] m/s, feed rate ∈ [150, 200] mm/min, and grinding depth ∈ [0.4, 0.5] mm. 相似文献