Papers by Author: Ya Nan Zhang

Abstract: Wireless communication technology has been widely applied in People's Daily life. However, limited spectrum resources and low spectrum utilization of spectrum resources shortage is proposed. In this paper, a cognitive function of backoff algorithm (CR-BOA) is raised. This algorithm depending on the degree of congestion channel adaptive adjustment the size of the backoff value .This algorithm greatly improves the performance of the network, and reduces the problems of delay caused by the spectrum resource scarcity. Finally, use the OPNET simulation software, the results show that the end-to-end delay and the packet loss rate are reduced.

Abstract: The examination of outer cylinder of pipes in steam generators is difficult to fulfill due to confined space. A robotic system has been developed to do the job. The robot contains a base, four rotary balls, a slide guide, two steppers, a DC motor, a positioning mechanism, a synchromesh belt mechanism, a longitudinal mobile platform, an extending and retracting mechanism, a rotary platform and a micro vehicle. The positioning mechanism can locate and fix the robot efficiently. The motion of the robot consists of longitudinal motion and transverse motion. The extending and retracting mechanism can push and pull the micro vehicle carrying a micro CMOS camera. The pose of the camera mounted on the movable platform of a micro 3-CSR parallel mechanism can be adjusted by 3 bias-two-way SMA actuators. The control system consists of two levels of computers. The user interface was developed with VB. Fuzzy control method is utilized to control the motion of the longitudinal mobile platform. Grey evaluation method is applied to evaluate the status of checked areas according to obtained images. Experiment results indicate that the robot has met the needs of examination.