In the field of radio astronomy, the 21cm absorption line of HI is an important way to explore the large-scale structure and evolution history of the universe. The working frequency of FAST's 19 beam receiver is 1.05GHz to 1.45GHz, and the main observation object is to conduct an accurate and rapid intensity mapping survey of extragalactic HI’s signal. Aiming at the 21cm spectral line of the object, we designed a parallel data processing platform to mitigate the influence of foreground, instrument, radio frequency, standing wave and other noises on the spectral data, then generate the image data of the whole sky region. At present, we divide the process into flux calibration, bandpass and baseline correction, radio frequency interference marking and data gridding work, etc. The whole project was programmed in Python, and Cython was used for some projects to speed things up.
Upon its completion, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) will be the largest single dish
radio telescope ever in the world. The construction has been initiated in March 2011 in Guizhou province of China. The
whole construction process is expected to be completed in September 2016, with duration of 5.5 years.
With an aperture of 500 meters and an illumination aperture of 300 meters, the active reflector is one of the most
important parts of FAST. The reflector is composed of a ring beam, a cable net and thousands of panels, tie-down cables,
actuators and anchors. For the observation process of source switching and source tracking, the parabola shape of the
reflector is achieved by drawing back of the tie-down cables by the actuators. The motion performance and the reliability
of the actuators are of great importance to the telescope.
In this paper, the motion models of the actuators are analyzed for the observation process of source switching and source
tracking. Several design schemes are proposed, including mechanical and hydraulic design. The electric, mechanical and
hydraulic characteristics of these designs are discussed. Related experimental studies are performed to investigate the
electric and mechanical performances of these actuator prototypes. Based on the analysis and test results, a final type of
actuator will be optimally concluded to meet the requirements of the reflector of FAST.