National disparities of air pollution exposure level by socioeconomic status in China

Wang, Y; Bechle, Matthew J.; Xu, Hui; Chen, X; Cui, Heng; Wang, Y; Zhao, Yuan; Marshall, Julian

doi:10.1097/01.ee9.0000610744.21669.36

Cited by 1 publication

(1 citation statement)

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“…However, ignoring the antenna pointing accuracy is the result of the joint effect of the antenna base axis error and the reflector deformation, which leads to precision limitations. The pointing error analysis model for control is often based on modal superposition method and the approximate optical method, but this method depends on the accuracy of the error model, and the estimated pointing accuracy often has a large error (Yu & Fan 2019).…”

Section: Introductionmentioning

confidence: 99%

Analysis and compensation of the reflector antenna pointing error under wind disturbance

Zhang

Wang

et al. 2021

Res. Astron. Astrophys.

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A large reflector antenna has been widely used in satellite communications, gravitational wave detection, galaxy origin observation and other fields due to its narrow beam and high gain. With the increase of the antenna aperture and the improvement of the working frequency, the requirements for the pointing accuracy of an antenna are also rising. However, the effect of environmental load on the deformation of the antenna structure, which in turn affects its beam pointing, has become a key problem to be solved urgently in the antenna engineering applications. The key issue to solving this problem involves accurately estimating the pointing error caused by the structural deformation and designing an effective controller that is based on the structural deformation. In this paper, we first establish a dynamic model for antenna structure based on the modal superposition method. The model is then modified by using modal characteristics and the dynamic displacement information of the sampling points to achieve the purpose of accurately estimating the structural deformation. Secondly, by considering the influence of the deformation of the rotating shaft and the reflector surface on the pointing accuracy, a control-oriented pointing error analysis model is established for estimating the pointing error caused by the environmental load in real time. Thirdly, based on considering the influence of the shaft deformation on the error compensation, the feedback error amount is decoupled and corrected to improve the accuracy of the compensation error. Finally, this paper analyzes and verifies the 65 m S/X-band dual reflector antenna with a numerical example. We consider a fluctuating wind with an average wind speed of 10 m s−1 as an example, which results in a maximum pointing error of 55.82″ as calculated by the antenna theoretical model, whereas the maximum pointing error as predicted by our model is 68.27″. The pointing error after compensating for the cause of the environmental load with the modified controller is reduced to 10.57″, which effectively improves the antenna pointing performance.

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Section: Introductionmentioning

confidence: 99%