Domain ontology can effectively organize the knowledge of that domain and make it easier to share and reuse. We can build domain ontology on thesaurus and thematic words and index document knowledge using domain ontology. Under which this paper designs a semantic retrieval system for the document knowledge based on domain ontology, and the system consists of four main components: ontology query, semantic precomputation for document and the concept similarity, semantic extended search and reasoning search. Finally, this paper makes an experiment on high-speed railway domain. The experimental results show that the developed semantic retrieval system can reach the satisfied recall and precision.

: Multimedia assisted teaching plays a more and more important role in modern teaching. It not only can improve the teaching quality, but also provides a platform for the reform of traditional teaching mode and method. For at present classroom utilization rate is low, the fault report and maintenance is not timely, its separate control is not easy to manage, and so on, a set of centralized control system for multimedia classroom equipment is developed by increasing the necessary hardware on the basis of existing multimedia equipment, which is based on network and wireless data transmission technology. A main controller and its peripheral equipment interface circuit are designed, including hardware and software. The system can improve the utilization rate and service life of multimedia equipment, convenient the effective management.

The article presents a novel cluster selection algorithm from the point of the network security. The measure uses Kruskal algorithm to calculate the minimum spanning tree of the topological structure of wireless Ad Hoc networks and builds clustering on it which ensures the cost of communication among cluster nodes that keeps in a relatively low level. The algorithm for the NIDS (network intrusion detection system) of wireless Ad hoc provides a stable and effective support and enhances the survivability of the system. The result of simulation experiment shows that the measure has good performance.