This paper contains a review of technologies, theoretical studies for optical communications from and to high-altitude platforms (HAPs). We discuss how to use optical communication to transmit data at multi-Gigabits in HAP to HAP and HAP to Satellite. The influence of the atmosphere, background light and other noise are discussed in this paper, we explain the advantages and disadvantages of free-space optical communications. And the performance of HAPs (High Altitudes Platforms) WiMAX is studied for different HAPs heighth and transmitted power level in different transmission format. The coverage radius increases with the transmitted power increment and with the operating frequency reduction
The type, shape and distribution of inclusions in ductile cast iron were studied using a scanning electron microscopy (SEM) and the energy spectrum analysis, combining the thermodynamic calculation of inclusions formation. The results show that the oxides are most likely formed from the thermodynamics in ductile cast iron when the temperature is 1373~1873 K , followed by the sulfides, the carbides again. There exist the uniphase inclusions MgO, SiO2and MgS, the heterogeneous inclusions of containing rare-earth MnO-MgO-SiO2-La2O3and MgS-LaS-SiO2-Al2O3-MgO , and the heterogeneous inclusions of non-rare earth SiO2-MnO-MgO-Al2O3in ductile cast iron. The shapes of the inclusions are mainly polygon, and the size variation is from 3 to 10 um. The inclusions are mainly distributed on the graphite ball surfaces, the ferrite grain boundaries and in the pearlites.
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