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The immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge (HZMB) is the first of its kind constructed using semi-rigid elements and making a breakthrough in the structural theory. This paper explains the reason for applying the semi-rigid elements in an immersed tunnel and provides the design details using the example of the HZMB Tunnel. A theoretical analysis method based on the body-spring model is proposed for segmental joints of the semi-rigid elements. Potential challenges in the application of the semi-rigid elements are identified. Compared with the rigid (monolithic) elements and flexible (segmental) elements, the semi-rigid elements can improve the safety of segmental joints by increasing the flexural rigidity and joint friction. In addition, applying the semi-rigid elements can reduce the construction cost by retaining prestressed cables. Despite the advantages of the semi-rigid elements, some uncertainties arise due to the functional change of prestressed cables from a temporary structure to a permanent one. The location, number, and prestress level of the remaining prestressed cables need to be studied in accordance with the mechanical and waterproofing properties. The long-term prestress loss of prestressed cables should also be taken into consideration, especially the loss of asymmetric prestress in a marine environment. With the development of economy in costal regions, more immersed tunnels will face the similar engineering geological problems as the HZMB Tunnel. Discussing the technology of semi-rigid element has both engineering and theoretical significance to the development of immersed tunnels.

This paper is taking the Baise-Leye highway as the study area, using 3D technique to investigate the eco-environment. With the advancement of computer technology, especially the development of GIS technology, the paper is using the 3D GIS technique in the field of highway engineering will be more profound. The authors are taking the UAV image to extract 3D network and model, based on 3D model, the authors carry out highway environment simulation analysis. The authors also construct pollution assessment method to evaluate of road environment information.

For wireless mesh networks has no support infrastructure and shows a highly dynamic feature, routing becomes a key problem to be solved. Data packets are transmitted on a path that had least hops in AODV protocol. It couldn't consider the path stability. When the node of wireless mesh networks moved quickly and the path had short lifetime, the path recovery and routing again is caused. It is a lot of network resource. For network performance, AODV_D that improvement of AODV based on DSDV is provided to improve AODV protocol in the paper. It used structuring a DSDV-based routing table driven technology to select the less hops but high stability path to send data packets. Static node activates AODV_D routing protocol, sports node can choose artificially to activate or not activate this routing mechanism. NS-2 simulation results show that AODV_D routing protocol can improve the delivery rate of data packets, reduce the average end to end delay and packet-loss-rate.

The broadcast and multicast service will play a major role in the future wireless communication. The enhanced broadcast and multicast system (EBCMCS) is the evolution of cdma2000 EV/DO in the broadcast system, and can provide the point-to-multipoint broadcast service. In this paper, the quadrature PN spreading and de-spreading methods in the EBCMCS of cdma2000 EV-DO are investigated, and a quadrature PN de-spreading method with lower complexity is proposed. Also, its complexity is compared with the traditional method. Finally, it is proved that the proposed method has much lower complexity than the conventional one without degrading the effectiveness.