123 research outputs found
Efficient Raw Signal Generation Based on Equivalent Scatterer and Subaperture Processing for SAR with Arbitrary Motion
An efficient SAR raw signal generation method based on equivalent scatterer and subaperture processing is proposed in this paper. It considers the radarâs motion track, which can obtain the precise raw signal for the real SAR. First, the imaging geometry with arbitrary motion is established, and then the scene is divided into several equidistant rings. Based on the equivalent scatterer model, the approximate expression of the SAR system transfer function is derived, thus each pulseâs raw signal can be generated by the convolution of the transmitted signal and system transfer function, performed by the fast Fourier transform (FFT). To further improve the simulation efficiency, the subaperture and polar subscene processing is used. The system transfer function of pluses for the same subaperture is calculated simultaneously by the weighted sum of all subscenesâ equivalent backscattering coefficient in the same equidistant ring, performed by the nonuniform FFT (NUFFT). The method only involves the FFT, NUFFT and complex multiplication operations, which means the easier implementation and higher efficiency. Simulation results are given to prove the validity of this method
High resolution characterization of the Asian Monsoon between 146,000 and 99,000 years B.P. from Dongge Cave, China and global correlation of events surrounding Termination II
Improvement of nonâlinear chirpâscaling algorithm for highly squint bistatic SAR data focusing
Paradigmatic Semantic Network Construction of Psychological Adjectives in Mandarin ChineseâWith a Case of Semantic Metadata Network Denoting èȘæ Congming âSmartâ
Absolute phase determination for lowâfrequency ultraâwideband synthetic aperture radar interferometry
Determination of the number of J/Ï events with inclusive J/Ï decays
A measurement of the number of J/Ï events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/Ï. The number of J/Ï events taken in 2009 is recalculated to be (223.7 ± 1.4) Ă 106, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/Ï events taken in 2012 is determined to be (1086.9 ± 6.0) Ă 106. In total, the number of J/Ï events collected with the BESIII detector is measured to be (1310.6 ± 7.0) Ă 106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible
Measurements of the center-of-mass energies at BESIII via the di-muon process
From 2011 to 2014, the BESIII experiment collected about 5 fb-1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e+e- â ÎłISR/FSRÎŒ+ÎŒ-, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of the time during data taking
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