A phoxonic crystal waveguide with the glide symmetry is designed,in which both electromagnetic and elastic waves can propagate along the glide plane at the same time.Due to the glide symmetry,the bands of the phoxonic...A phoxonic crystal waveguide with the glide symmetry is designed,in which both electromagnetic and elastic waves can propagate along the glide plane at the same time.Due to the glide symmetry,the bands of the phoxonic crystal super-cell degenerate in pairs at the boundary of the Brillouin zone.This is the so-called band-sticking effect and it causes the appearance of gapless guided-modes.By adjusting the magnitude of the glide dislocation the edge bandgaps,the bandgap of the guided-modes at the boundary of the Brillouin zone,can be further adjusted.The photonic and phononic guided-modes can then possess only one mode for a certain frequency with relatively low group velocities,achieving single-mode guided-bands with relatively flat dispersion relationship.In addition,there exists acousto-optic interaction in the cavity constructed by the glide plane.The proposed waveguide has potential applications in the design of novel optomechanical devices.展开更多
The entry-glide guidance strategy for hypersonic vehicles that can satisfy both terminal and path constraints is investigated in this paper.We propose a quasi-equilibrium glide adaptive guidance methodology based on t...The entry-glide guidance strategy for hypersonic vehicles that can satisfy both terminal and path constraints is investigated in this paper.We propose a quasi-equilibrium glide adaptive guidance methodology based on the quasi-equilibrium glide condition(QEGC),which innovatively utilizes the quasi-equilibrium glide phenomenon in lifting entry.With the aid of QEGC,both range and terminal velocity can be predicted analytically with high precision.The path constraints are converted into angle of attack constraints,which has been difficult to realize by using traditional predictive guidance methods.The algorithm is independent of the standard trajectory.All the guidance commands,including the bank angle and the angle of attack,are calculated analytically in real time,which endows the algorithm with sufficient adapbility.The results of a CAV-H vehicle guidance test show that the algorithm leads the vehicle along a quasi-equilibrium glide trajectory satisfying both the terminal and path constraints and has sufficient flexibility for occasional mission changes.Furthermore,the robustness of the guidance algorithm under disturbances is validated through a Monte Carlo simulation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12064025)the Natural Science Foundation of Jiangxi Province,China(Grant No.20212ACB202006)+1 种基金the Major Discipline Academic and Technical Leaders Training Program of Jiangxi Province,China(Grant No.20204BCJ22012)the Open Project of the Key Laboratory of Radar Imaging and Microwave Photonic Technology of the Education Ministry of China.
文摘A phoxonic crystal waveguide with the glide symmetry is designed,in which both electromagnetic and elastic waves can propagate along the glide plane at the same time.Due to the glide symmetry,the bands of the phoxonic crystal super-cell degenerate in pairs at the boundary of the Brillouin zone.This is the so-called band-sticking effect and it causes the appearance of gapless guided-modes.By adjusting the magnitude of the glide dislocation the edge bandgaps,the bandgap of the guided-modes at the boundary of the Brillouin zone,can be further adjusted.The photonic and phononic guided-modes can then possess only one mode for a certain frequency with relatively low group velocities,achieving single-mode guided-bands with relatively flat dispersion relationship.In addition,there exists acousto-optic interaction in the cavity constructed by the glide plane.The proposed waveguide has potential applications in the design of novel optomechanical devices.
基金supported by the National Natural Science Foundation of China (Grant No. 61104200)
文摘The entry-glide guidance strategy for hypersonic vehicles that can satisfy both terminal and path constraints is investigated in this paper.We propose a quasi-equilibrium glide adaptive guidance methodology based on the quasi-equilibrium glide condition(QEGC),which innovatively utilizes the quasi-equilibrium glide phenomenon in lifting entry.With the aid of QEGC,both range and terminal velocity can be predicted analytically with high precision.The path constraints are converted into angle of attack constraints,which has been difficult to realize by using traditional predictive guidance methods.The algorithm is independent of the standard trajectory.All the guidance commands,including the bank angle and the angle of attack,are calculated analytically in real time,which endows the algorithm with sufficient adapbility.The results of a CAV-H vehicle guidance test show that the algorithm leads the vehicle along a quasi-equilibrium glide trajectory satisfying both the terminal and path constraints and has sufficient flexibility for occasional mission changes.Furthermore,the robustness of the guidance algorithm under disturbances is validated through a Monte Carlo simulation.
