This paper reviews solar sail trajectory design and dynamics,attitude control,and structural dynamics.Within the area of orbital dynamics,methods relevant to transfer trajectory design and non-Keplerian orbit generati...This paper reviews solar sail trajectory design and dynamics,attitude control,and structural dynamics.Within the area of orbital dynamics,methods relevant to transfer trajectory design and non-Keplerian orbit generation are discussed.Within the area of attitude control,di erent control strategies,including utilisation of solar radiation pressure and conventional actuators,are discussed.Finally,the methods of modelling structural dynamics during and after deployment are discussed,before considering possible future trends in developing of solar sailing missions.展开更多
The molecular structures and the vibrational frequencies of uranium hexahalides UX6 （X=F, Cl, Br and I） molecules are investigated by using local density approximation （LDA） and generalised gradient approximation ...The molecular structures and the vibrational frequencies of uranium hexahalides UX6 （X=F, Cl, Br and I） molecules are investigated by using local density approximation （LDA） and generalised gradient approximation （GGA） functions （BP, BLYP and RPBE） in combination with two different relativistic methods （scalar and scalar＋spin-orbit relativistic effects）. The calculated results show that the differences are trivial between scalar and scalar＋spin-orbit relativistic methods. The vibrational frequencies are also compared with existing experimental values, and overall, the RPBE approach gives the smallest error. The bond dissociation energies （BDEs） of UX6 are computed by using the RPBE function, thereby obtaining exact vibrational frequencies. In addition, the calculated magnitudes of the spin orbit effect on the BDE of UX6 （X=F, Cl, Br, and I） are found to be approximately -0.3198, 0.3218, -0.3609 and -0.4415 eV, respectively.展开更多
Hamiltonian structure of a rigid body in a circular orbit is established in this paper. With the reduction technique, the Hamiltonian structure of a rigid body in a circular orbit is derived from Lie-Poisson structure...Hamiltonian structure of a rigid body in a circular orbit is established in this paper. With the reduction technique, the Hamiltonian structure of a rigid body in a circular orbit is derived from Lie-Poisson structure of semidirect product, and Hamiltonian is derived from Jacobi's integral. The above method can be generalized to establish the Hamiltonian structure of a rigid body with a flexible attachment in a circular or- bit. At last, an example of stability analysis is given.展开更多
An open-loop control system for hovering at any selected position on spacecraft orbit is first presented given that the satellite＇s engine provides continuous finite thrust. Actually, the hovering states are unstable...An open-loop control system for hovering at any selected position on spacecraft orbit is first presented given that the satellite＇s engine provides continuous finite thrust. Actually, the hovering states are unstable considering perturbations and thrust errors, so a feedback sliding mode variable structure control, which is adaptive and chattering-free, is designed. Under this feedback control scheme, the high-frequency chattering phenomenon is avoided, while the system stays highly robust at the same time. Simulation results show that the feedback control thrusts are continuous and the steady-states error can be confmed to 10-4 m at the presence of uncertain perturbations. Finally, the feasibility of realizing hovering orbits is analyzed taking the ＂Moliya＂ and geosynchronous Earth orbit （GEO） satellites as examples.展开更多
Ⅰ. INTRODUCTIONApplying the approximate model potential theory to multi-electron atoms or ions suggested in Zheng’s papers, the authors of the present note have derived a general expression for the calculation of ma...Ⅰ. INTRODUCTIONApplying the approximate model potential theory to multi-electron atoms or ions suggested in Zheng’s papers, the authors of the present note have derived a general expression for the calculation of matrix elements of the operator r^k with arbitrary power order k, which can be applied in calculating various transition oscillator strengths. In order to study the multiplet structure at any excited state, we need to calculate the spin-orbit coupling ener-展开更多
In this work, the band structure and optical-related properties of CuIn0.5Ga0.5Se2 thin film are presented. The calculation is performed by the full-potential linearized augmented plane wave (FPLAPW) method. The spin-...In this work, the band structure and optical-related properties of CuIn0.5Ga0.5Se2 thin film are presented. The calculation is performed by the full-potential linearized augmented plane wave (FPLAPW) method. The spin-orbit coupling is considered. The result for the dielectric function is in good agreement with earlier experimental measurements and simulations. Based on the complex dielectric function, the dielectric constant, the absorption coefficient, the complex refractive index and the reflectivity at normal incidence are explored. We found that they are comparable with the earlier results.展开更多
Over the last few years,researches in iridates have developed into an exciting field with the discovery of numerous emergent phenomena,interesting physics,and intriguing functionalities.Among the studies,iridate-based...Over the last few years,researches in iridates have developed into an exciting field with the discovery of numerous emergent phenomena,interesting physics,and intriguing functionalities.Among the studies,iridate-based artificial structures play a crucial role owing to their extreme flexibility and tunability in lattice symmetry,chemical composition,and crystal dimensionality.In this article,we present an overview of the recent progress regarding iridate-based artificial structures.We first explicitly introduce several essential concepts in iridates.Then,we illustrate important findings on representative SrIrO_(3)/SrTiO_(3) superlattices,heterostructures comprised of SrIrO3 and magnetic oxides,and their response to external electric-field stimuli.Finally,we comment on existing problems and promising future directions in this exciting field.展开更多
Starting from iterated systems, it is shown that the homoclinic (heteroclinic) orbit is a kind of spiral structure. The emphasis is laid to show that there are homoclinic or heteroclinic orbits in complex discrete and...Starting from iterated systems, it is shown that the homoclinic (heteroclinic) orbit is a kind of spiral structure. The emphasis is laid to show that there are homoclinic or heteroclinic orbits in complex discrete and continuous systems, and these homoclinic or heteroclinic orbits are some kind of spiral structure.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.117722167 and 11822205).
文摘This paper reviews solar sail trajectory design and dynamics,attitude control,and structural dynamics.Within the area of orbital dynamics,methods relevant to transfer trajectory design and non-Keplerian orbit generation are discussed.Within the area of attitude control,di erent control strategies,including utilisation of solar radiation pressure and conventional actuators,are discussed.Finally,the methods of modelling structural dynamics during and after deployment are discussed,before considering possible future trends in developing of solar sailing missions.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60278020)
文摘The molecular structures and the vibrational frequencies of uranium hexahalides UX6 （X=F, Cl, Br and I） molecules are investigated by using local density approximation （LDA） and generalised gradient approximation （GGA） functions （BP, BLYP and RPBE） in combination with two different relativistic methods （scalar and scalar＋spin-orbit relativistic effects）. The calculated results show that the differences are trivial between scalar and scalar＋spin-orbit relativistic methods. The vibrational frequencies are also compared with existing experimental values, and overall, the RPBE approach gives the smallest error. The bond dissociation energies （BDEs） of UX6 are computed by using the RPBE function, thereby obtaining exact vibrational frequencies. In addition, the calculated magnitudes of the spin orbit effect on the BDE of UX6 （X=F, Cl, Br, and I） are found to be approximately -0.3198, 0.3218, -0.3609 and -0.4415 eV, respectively.
基金The projeet supported by National Natural Science Foundation of China and Aeronautic Science Foundation.
文摘Hamiltonian structure of a rigid body in a circular orbit is established in this paper. With the reduction technique, the Hamiltonian structure of a rigid body in a circular orbit is derived from Lie-Poisson structure of semidirect product, and Hamiltonian is derived from Jacobi's integral. The above method can be generalized to establish the Hamiltonian structure of a rigid body with a flexible attachment in a circular or- bit. At last, an example of stability analysis is given.
基金supported by the National Natural Science Foundation of China (Grant No. 10702078)the National Basic Research Program of China ("973" Program) (Grant No. JC08-01-05)
文摘An open-loop control system for hovering at any selected position on spacecraft orbit is first presented given that the satellite＇s engine provides continuous finite thrust. Actually, the hovering states are unstable considering perturbations and thrust errors, so a feedback sliding mode variable structure control, which is adaptive and chattering-free, is designed. Under this feedback control scheme, the high-frequency chattering phenomenon is avoided, while the system stays highly robust at the same time. Simulation results show that the feedback control thrusts are continuous and the steady-states error can be confmed to 10-4 m at the presence of uncertain perturbations. Finally, the feasibility of realizing hovering orbits is analyzed taking the ＂Moliya＂ and geosynchronous Earth orbit （GEO） satellites as examples.
文摘Ⅰ. INTRODUCTIONApplying the approximate model potential theory to multi-electron atoms or ions suggested in Zheng’s papers, the authors of the present note have derived a general expression for the calculation of matrix elements of the operator r^k with arbitrary power order k, which can be applied in calculating various transition oscillator strengths. In order to study the multiplet structure at any excited state, we need to calculate the spin-orbit coupling ener-
文摘In this work, the band structure and optical-related properties of CuIn0.5Ga0.5Se2 thin film are presented. The calculation is performed by the full-potential linearized augmented plane wave (FPLAPW) method. The spin-orbit coupling is considered. The result for the dielectric function is in good agreement with earlier experimental measurements and simulations. Based on the complex dielectric function, the dielectric constant, the absorption coefficient, the complex refractive index and the reflectivity at normal incidence are explored. We found that they are comparable with the earlier results.
基金support from the National Natural Science Foundation of China(NSFC)under grant No.51872155 and 52025024the Beijing Nature Science Foundation(Z200007)+4 种基金the Ministry of Science and Technology of China(2021YFE0107900 and 2021YFA1400300)support from the High Magnetic Field Laboratory of Anhui Province(AHHM-FX-2021-03)the NSFC under Grant No.12104460support from the NSFC under Grant No.92163113 and No.52250418support from the National Science Foundation under Grant No.DMR1848269.
文摘Over the last few years,researches in iridates have developed into an exciting field with the discovery of numerous emergent phenomena,interesting physics,and intriguing functionalities.Among the studies,iridate-based artificial structures play a crucial role owing to their extreme flexibility and tunability in lattice symmetry,chemical composition,and crystal dimensionality.In this article,we present an overview of the recent progress regarding iridate-based artificial structures.We first explicitly introduce several essential concepts in iridates.Then,we illustrate important findings on representative SrIrO_(3)/SrTiO_(3) superlattices,heterostructures comprised of SrIrO3 and magnetic oxides,and their response to external electric-field stimuli.Finally,we comment on existing problems and promising future directions in this exciting field.
文摘Starting from iterated systems, it is shown that the homoclinic (heteroclinic) orbit is a kind of spiral structure. The emphasis is laid to show that there are homoclinic or heteroclinic orbits in complex discrete and continuous systems, and these homoclinic or heteroclinic orbits are some kind of spiral structure.
