Well’. If a tiny island was fortified, it was likely intended
Well’. If a modest island was fortified, it was in all probability intended to be a secure military base `because with the safety and isolation’ that it offers for military operations (Constantakopoulou 2007, p. 120).Religions 2021, 12,16 ofThe presence of fresh-water wells, so crucial for the inhabitants, within this part of the island naturally necessitated the constructing in the fort right here to defend this resource. In accordance with Salles (1985, p. 580) the ceramic proof found in the region areas the erection from the fortress in the very first half on the 3rd century BC. Jeppesen (1989, pp. 736) believes that the two temples might have been built later, Temple A dating roughly to 260 BC and Temple B to about 240 BC. The island of Ikaros/Failaka inside the Persian Gulf was named following the Aegean island Ikaros in the Aegean.
remote sensingArticleBDS Satellite Clock Prediction Thinking of SC-19220 Antagonist periodic VariationsLin Zhao 1 , Nan Li 1 , Hui Li 1,2, , Renlong Wang 1 and Menghao LiCollege of Intelligent Systems Science and Engineering, Harbin Engineering University, Harbin 150001, China; [email protected] (L.Z.); [email protected] (N.L.); [email protected] (R.W.); [email protected] (M.L.) HEU Qingdao Ship Science and Technologies Co., Ltd., Qingdao 266400, China Correspondence: [email protected]; Tel.: +86-0451-Citation: Zhao, L.; Li, N.; Li, H.; Wang, R.; Li, M. BDS Satellite Clock Prediction Thinking of Periodic Variations. Remote Sens. 2021, 13, 4058. https://doi.org/10.3390/rs13204058 Academic Editor: Pietro Tizzani Received: 10 September 2021 Accepted: six October 2021 Published: 11 OctoberAbstract: The periodic noise exists in BeiDou navigation satellite technique (BDS) clock offsets. As a normally employed satellite clock prediction model, the spectral evaluation model (SAM) typically detects and identifies the periodic terms by the Fast Fourier transform (FFT) in line with long-term clock offset series. The FFT tends to make an aggregate assessment in frequency domain but cannot characterize the periodic noise inside a time domain. As a consequence of space atmosphere changes, temperature variations, and different disturbances, the periodic noise is time-varying, plus the spectral peaks vary more than time, that will influence the prediction accuracy on the SAM. Within this paper, we investigate the periodic noise and its variations present in BDS clock offsets, and increase the clock prediction model by thinking of the periodic variations. The periodic noise and its variations more than time are analyzed and quantified by quick time Fourier transform (STFT). The results show that both the amplitude and frequency with the most important periodic term in BDS clock Hydroxyflutamide Epigenetics offsets differ with time. To minimize the influence of periodic variations on clock prediction, a time frequency analysis model (TFAM) based on STFT is constructed, in which the periodic term can be quantified and compensated accurately. The experiment final results show that each the fitting and prediction accuracy of TFAM are much better than SAM. Compared with SAM, the average improvement of the prediction accuracy working with TFAM on the six h, 12 h, 18 h and 24 h is within the array of 6.four to ten for the GNSS Research Center of Wuhan University (WHU) clock offsets, and 11.1 to 14.four for the Geo Forschungs Zentrum (GFZ) clock offsets. For the satellites C06, C14, and C32 with marked periodic variations, the prediction accuracy is enhanced by 26.7 , 16.two , and 16.three for WHU clock offsets, and 29.eight , 16.0 , 21.0 , and 9.0 of C06, C14, C28, and C32 for GFZ clock offsets. Keywor.