Improved Time-Varying Controller Based on Parameter Optimization for Libration-Point Orbit Maintenance

2016 ◽  
Vol 29 (1) ◽  
pp. 04015010 ◽  
Author(s):  
Chunfeng Yang ◽  
Haijun Peng ◽  
Shujun Tan ◽  
Yunpeng Li ◽  
Biaosong Chen
Keyword(s):  
Parameter Optimization ◽  
Libration Point ◽  
Time Varying ◽  
Orbit Maintenance

scholarly journals From Asymmetrical to the Nonreciprocal Isolator Using Time-varying Metasurfaces

2021 ◽  
Author(s):  
Yaser Khorrami ◽  
DAVOOD Fathi ◽  
Amin Khavasi ◽  
Raymond C. Rumpf
Keyword(s):  
Photonic Crystal ◽  
Numerical Analysis ◽  
Transfer Matrix ◽  
Parameter Optimization ◽  
Optimization Algorithm ◽  
Time Variation ◽  
Transfer Matrix Method ◽  
Design Method ◽  
Time Varying ◽  
Permittivity And Permeability

Abstract We present an emulation design method for converting asymmetric isolators to nonreciprocal ones using time-varying metasurfaces. To illustrate the model, we design a structure using a combination of the photonic crystal (PhC) and time-varying metasurface. Moreover, we propose a general approach for numerical analysis of the time-modulated proposed structure using the extension of the transfer matrix method (TMM) which consists of working through the device one layer at a time and calculating an overall transfer matrix including the time-variation of the permittivity and permeability in each layer. Also, we use an optimization algorithm that is less used in the field of electromagnetism but is suitable for fast and accurate parameter optimization. The results show that the proposed method, using pure time-varying metasurfaces which cannot prepare full nonreciprocity alone, is a promising procedure for breaking the Lorentz reciprocity in the general isolator system as well as maintaining the previously asymmetric designed structure.

scholarly journals Research on the Lissajous Trajectory Transfer of Large Area Mass Ratio Solar Sail Spacecraft

2020 ◽  
Vol 38 (5) ◽  
pp. 1054-1062
Author(s):  
Xun Duan ◽  
Xiaokui Yue
Keyword(s):  
Periodic Orbit ◽  
Libration Point ◽  
Cone Angle ◽  
Solar Sail ◽  
Large Area ◽  
Orbit Transfer ◽  
Light Pressure ◽  
Orbit Maintenance ◽  
Lissajous Orbit ◽  
Pressure Factor

Considering that the solar sail spacecraft working in the Lissajous orbit will be affected by the shadow of the earth or the solar wind, which sometime makes the spacecraft unable to work, we try to use the solar light pressure as the thrust to carry out the Lissajous orbit transfer in advance. Because the solar pressure parameters(cone angle, clock angle and solar pressure factor) will change the position of the libration points, we propose the idea of splicing the old and new libration point manifolds to transfer the escape spacecraft to the new Lissajous orbit to achieve orbit maintenance. The simulation results show that besides changing the cone angle and the solar pressure factor, the clock angle can also achieve orbit transfer, and the influence of the solar pressure factor on the periodic orbit is greater than the other two. This study provides a reference for the solar sail spacecraft in the aspects of periodic orbit transfer, orbit maintenance and avoidance of the earth's shadows.

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