Free-space optical communications(ultraviolet and infrared communications) have emerged as a viable alteniative to RF communication for many applications. Ultraviolet communication system even can provide non-line- of...
详细信息
Free-space optical communications(ultraviolet and infrared communications) have emerged as a viable alteniative to RF communication for many applications. Ultraviolet communication system even can provide non-line- of-sight links by exploiting atmospheric scattering of Atmospheric turbulence can causes fluctuations in the intensity of the received signal,impairing link performance. Many theoretical models about atmospheric turbulence have been proposed to describe tuibulence-induced intensity fluctuations. Though some models are single to implement,they are often used to model some turimlence conditions. Others have excellent fit with measurement data for a wide range of turbulence conditions,but they are complex and difficull to implement. In this paper,we present an adaptive method to select the different simple tuibulence model based on the scintillation index in different tuibulence conditions and detect the signals in the Poisson and Gauss regime,when the light fluctuations exit in ultraviolet and infrared ccmimunication.
The solar array whose quality has great influence on the work efficiency of the spacecraft is the most important power supply system and the honeycomb sandwich panel which has high specific strength and stiffness is t...
详细信息
The solar array whose quality has great influence on the work efficiency of the spacecraft is the most important power supply system and the honeycomb sandwich panel which has high specific strength and stiffness is the perfect material for solar *** finite element model(FEM) of the honeycomb sandwich panel includes idealized hypothesis and simplification,which results in the difference between the calculating data and the test *** this paper the honeycomb sandwich panel is equivalent to a structure which can be calculated by NASTRAN based on the equivalence theory and then the improved Genetic- Partical Swarm Optimization(GA-FSO) algorithm is used to update the FEM,the updated precision and efficiency of the GA,PSO and GA- PSO are compared and the results show that these random search algorithms can update high order modes even use the incomplete low order *** improved GA-PSO algorithm can use GA to efficiently search for the global optimal solution at the early stage,and use PSO to intensively search for the local optimal solution at the later stage,it has higher searching efficiency and precision,the updated model has good approaching and prediction ability and can be taken as the fiducial model for the following calculation.
暂无评论