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61.
Yang Yang Yu Zheng Wenkun Yu Wu Chen Duojie Weng 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3303-3314
GNSS reflectometry (GNSS-R) has been widely studied in recent years for various applications, such as soil moisture monitoring, biomass analysis, and sea state monitoring. This paper presents the concept of a novel application of using GNSS-R technology for deformation monitoring. Instead of installing GNSS on the deformation body to sense the movement, GNSS-R deformation monitoring system estimates the deformation from receiving GNSS signal reflected by the deformation body remotely. A prototype of GNSS-R deformation monitoring system has been developed based on GNSS software receiver technology. A 3D geometrical model of GNSS signal reflection has been used to reveal the relationship between the change of carrier phase difference and deformation. After compensating the propagation path delay changes caused by satellite movement, the changes in the remaining carrier phase difference are linked to the deformation. Field tests have been carried using the GNSS-R system developed and the results show sub-centimeter level deformation can be observed with the new technology. Unlike other GNSS deformation monitoring methods, GNSS-R receivers are not installed on the slope which makes this new technology more attractive. 相似文献
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63.
Szu-Pyng Kao Yuh-Min Tu Shengyue Ji Wu Chen Zhenjie Wang Duojie Weng Xiaoli Ding Ting Hu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The ionosphere is an important part of the atmosphere and it is the largest error source of GNSS positioning for single-frequency users. So establishing a precise ionosphere model is one of the critical steps for satellite navigation and also for ionospheric research. 相似文献
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65.
实验研究了可调唇口对大攻角下S弯进气道内气流压力场的作用。在攻角从0°到80°、唇口角从0°到50°的实验条件下,分别测量了S弯进气道的4个壁面沿程静压以及管道出口截面静压。结果表明:如果没有可调唇口技术,随着攻角增大,S弯进气道内的压力会大大减小。可调唇口大大地提高了进气道压力,改善了进气道的预扩压性能 相似文献
66.
研究了隐式AF有限差分理论。指出薄层抛物化控制方程中的右端粘性项是主元素变量矢的一个简单线性函数。给出了任意边界扩压器内紊流流动的数值计算结果,并和实验数据进行了对照。两者吻合得相当好。研究结果对AF有限差分理论以及推广至三维复杂管道内的非定常流动计算具有重要的参考意义。 相似文献
67.
In this work, the Nb–14Si–24Ti–10Cr–2Al–2Hf–0.1Y alloy(at.%) was processed by the liquid–metal-cooled directional solidification(DS) at 1750 C with withdrawal rates of 1.2, 6,18 mm/min and post heat treatment(HT) at 1450 C for 10 h. The microstructures of the directionally solidified and heat treated samples were investigated. The results show that the microstructure of directionally solidified alloy mainly consists of petaloid Nbss+ Nb5Si3eutectics and Ti-rich Nbss+ Nb5Si3+ Cr2Nb eutectics. With the increase of withdrawal rate, the primary Nb5Si3is eliminated, Nbss+ Nb5Si3eutectic cells turn round and connected with the microstructure refinement and Nbss+ Nb5Si3+ Cr2Nb eutectics turn to a river-like morphology. After heat treatment,Nbss+ Nb5Si3+ Cr2Nb eutectics disappeared and petaloid Nbss+ Nb5Si3eutectics turn to a specific fiber-mesh structure gradually, which is promoted by higher withdrawal rates. Furthermore,both the volume fraction of Cr2Nb and the content of Cr in Nbssof Nbss+ Nb5Si3eutectics change regularly with the increase of withdrawal rate and heat treatment at 1450 C for 10 h. 相似文献