Liu Jiaqi

Decision-making method for small space aircraft navigation based on information fusion

A decision-making method of navigation for the small spacecraft is proposed. Attitude information is obtained by microelectromechanical gyroscope and geomagnetism sensor. Kalman filter and other information fusion techniques are used to improve the navigation accuracy. The long-term on-orbit navigation control of small aircraft is realized, reducing the cost of on-orbit navigation.A decision-making method of navigation for the small spacecraft is proposed. Attitude information is obtained by microelectromechanical gyroscope and geomagnetism sensor. Kalman filter and other information fusion techniques are used to improve the navigation accuracy. The long-term on-orbit navigation control of small aircraft is realized, reducing the cost of on-orbit navigation.

Infrared radiation measurement technique for low-temperature target in TV (thermal-vacuum) conditions

Aiming at the requirements of low-temperature measurement of spacecraft in thermal vacuum or thermal balance test, on the basis of the principle of infrared thermal measurement, the factors influencing the cool measurement of the infrared system were detailedly calculated and analyzed, from the targeted radiation, background radiation and radiation sensitivity of the detector infrared by the infrared system. It was found that the stray radiation of the optical system was the key link to restrict the cool measurement capability of the current hot test. On this result, a set of infrared thermal imaging system was designed, which could be used directly in the vacuum thermal test environment. In the optical system, the temperature could be cooled into -60°C. The blackbody was used to radiate and calibrate the system. As the experimental result showed, the system could be used to realize the infrared radiation measurement of the 150K cool target, which filled the blank of the technical field in china.

Equivalence on Quadratic Lyapunov Function Based Algorithms in Stochastic Networks

Quadratic Lyapunov function based Algorithms (QLAs) for stochastic network optimization problems, which are cross-layer scheduling algorithms designed by Lyapunov optimization technique, have been widely used and studied. In this paper, we investigate the performance of using Lyapunov drift and perturbation in QLAs. By analyzing attraction points and utility performance of four variants of OQLA (Original QLA), we examine the rationality of OQLA for using the first-order part of an upper bound of Lyapunov drift of a function L_1. It is proved that either using the real Lyapunov function (L_2) of networks under QLA or using the entire expression of Lyapunov drift does not improve backlog-utility performance. The linear relationship between the attraction point of backlog and perturbation in the queue is found. Simulations verify the results above.