多极化天线是利用处于同一安装位置的多个天线单元实现极化分集,充分利用电磁波多个场分量信息,克服多种极化方式天线系统的体积限制,极大的提高了有限空间内的空间自由度,可以满足多个频率通过同一付天线系统以不同极化方式广播的需求.本文提出了一种UHF电视频段多极化天线系统的设计思路,通过三维电磁仿真软件建模和仿真,得到同时支持水平极化、垂直极化、椭圆极化和圆极化等多工极化方式的电视天线系统.

中波天调系统是发射系统中的重要环节,它的好坏将直接关系到发射系统是否运行稳定以及技术指标的优劣.本文对新建台站的天线布局、多频共塔以及频率与塔之间的配置等方面进行相关讨论,对于其他中波发射台的建设具备一定参考意义.

An ontology based data description norm of web parts library is proposed.With the help of parts family and article characteristics table,the framework is built to solve the problem of parts data sharing and reusing.The generic and simple parts family is used to build the hierarchy and the article characteristics table is used to store the information of parts instances.Through the expansion of ontology library,the dynamic expansion of web parts library is realized.

Machine Vision was introduced into the navigation for UAV landing, and then a vision-aided semi-autonomous landing system was proposed. It was composed of four modules, performing image acquisition, image processing, navigation calculation, and platform control respectively. A multi-spectral camera and a laser range finder acquired the image and depth of the UAV. The image processing module calculated the position of the UAV with image segmentation and motion analysis methods. Kalman filtering in the navigation calculation rejected noises in position measurements, while simultaneously output filtered position for navigation and forecast position for visual tracking. Machine Vision algorithms were realized in real-time and a simulation system was established with virtual reality environment. Using reflective memory network, the simulation system was connected with other modules to fulfill distributed simulation of the landing procedure. In conclusion, the distributed simulation proved that the vision-aided semi-autonomous landing system was valid for UAV landing.

A novel second-order sliding model control (SOSMC) was proposed aiming at the inherent chattering of classical sliding mode control for high-precision attitude control of flexible launch vehicles, and the control law was designed according to super-twisting algorithm. Launch vehicle attitude control system is a very complex system with real parameter uncertainties and external disturbances in the process of flight for launch vehicle. The proposed SOSMC system can eliminate the chattering which may excite elastic mode with high frequency of launch vehicle without losing the robustness of system, and the dynamic responding of system was improved effectively. Simulation results demonstrate that the algorithm has good control performance and strong robustness.