A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve th...A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter（EKF） by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing（PDM） coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence（about 4 times quicker）compared to a conventional algorithm with optimal process noise covariance.展开更多
Shock wave/boundary layer interaction(SWBLI)continues to pose a significant chal-lenge in the field of aerospace engineering.This paper aims to address this issue by proposing a novel approach for predicting aerodynam...Shock wave/boundary layer interaction(SWBLI)continues to pose a significant chal-lenge in the field of aerospace engineering.This paper aims to address this issue by proposing a novel approach for predicting aerodynamic coefficients and heat trans-fer in viscous supersonic and hypersonic flows using a high-order flux reconstruction technique.Currently,finite volume methods are extensively employed for the compu-tation of skin aerodynamic coefficients and heat transfer.Nevertheless,these numerical methods exhibit considerable susceptibility to a range of factors,including the inviscid flux function and the computational mesh.The application of high-order flux recon-struction techniques offers promising potential in alleviating these challenges.In contrast to other high-order methods,the flux reconstruction is combined with the lat-tice Boltzmann flux solver in this study.The current method evaluates the common inviscid flux at the cell interface by locally reconstructing the lattice Boltzmann equa-tion solution from macroscopic flow variables at solution points.Consequently,this framework performs a positivity-preserving,entropy-based adaptive filtering method for shock capturing.The present approach is validated by simulating the double Mach reflection,and then simulating some typical viscous problems.The results demonstrate that the current method accurately predicts aerodynamic coefficients and heat trans-fer,providing valuable insights into the application of high-order methods for shock wave/boundary layer interaction.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61335005,61325023,and 61401378)
文摘A flexible polarization demultiplexing method based on an adaptive Kalman filter（AKF） is proposed in which the process noise covariance has been estimated adaptively. The proposed method may significantly improve the adaptive capability of an extended Kalman filter（EKF） by adaptively estimating the unknown process noise covariance. Compared to the conventional EKF, the proposed method can avoid the tedious and time consuming parameter-by-parameter tuning operations. The effectiveness of this method is confirmed experimentally in 128 Gb/s 16 QAM polarization-division-multiplexing（PDM） coherent optical transmission systems. The results illustrate that our proposed AKF has a better tracking accuracy and a faster convergence（about 4 times quicker）compared to a conventional algorithm with optimal process noise covariance.
基金This study was supported by the National Natural Science Foundation of China(Grant No.12072158)the Natural Science Foundation of Jiangsu Province(Grant No.BK20231437)the Research Fund of Key Laboratory of Computational Aerodynamics,AVIC Aerodynamics Research Institute(Grant No.YL2022XFX0402).
文摘Shock wave/boundary layer interaction(SWBLI)continues to pose a significant chal-lenge in the field of aerospace engineering.This paper aims to address this issue by proposing a novel approach for predicting aerodynamic coefficients and heat trans-fer in viscous supersonic and hypersonic flows using a high-order flux reconstruction technique.Currently,finite volume methods are extensively employed for the compu-tation of skin aerodynamic coefficients and heat transfer.Nevertheless,these numerical methods exhibit considerable susceptibility to a range of factors,including the inviscid flux function and the computational mesh.The application of high-order flux recon-struction techniques offers promising potential in alleviating these challenges.In contrast to other high-order methods,the flux reconstruction is combined with the lat-tice Boltzmann flux solver in this study.The current method evaluates the common inviscid flux at the cell interface by locally reconstructing the lattice Boltzmann equa-tion solution from macroscopic flow variables at solution points.Consequently,this framework performs a positivity-preserving,entropy-based adaptive filtering method for shock capturing.The present approach is validated by simulating the double Mach reflection,and then simulating some typical viscous problems.The results demonstrate that the current method accurately predicts aerodynamic coefficients and heat trans-fer,providing valuable insights into the application of high-order methods for shock wave/boundary layer interaction.
