Applied Mechanics and Materials Vols. 241-244

Abstract: Based on the analyses of intergroup complementary (IGC) codes and zero correlation zone complementary codes, novel IGC codes were proposed to adapt M-ary orthogonal code spreading spectrum system or quasi-synchronous CDMA system. The theoretical research and simulation results show that the main advantages of novel IGC are that under the same code length, the number of the novel IGC code sets are more than that of the intra-group IGC codes; the length of the zero correlation zone is longer than that of the intergroup IGC codes, but shorter than that of the intergroup IGC codes between groups; and under the same code length, the auto-correlation performance of the novel IGC codes is better than that of the IGC codes and both codes are of similar cross-correlation performance.

Abstract: For the encoding bit-rate problem in H.264 wireless video communication, the bit-rate computation model and the standard deviation distortion model were analyzed to establish the relation between the quantization parameter of encoding bit-rate and the intra-frame refresh rate of macroblocks, a new proposal of the coding rate thus put forward based on the general binomial computation model theory. Furthermore, this method not only can adaptively adjust the bit allocation and quantization parameters to prevent buffer from overflowing downward or upward under given network bandwidth, but also can apply the rate-distortion to perfect the solution method, control the encoding bits accurately and optimize the allocation between the inter-frame encoding macroblocks.

Abstract: A compact circularly polarized microstrip patch antenna was designed and fabricated based on the virtual load and limited airframe size of Unmanned Aerial Vehicles (UAV) applications. This antenna is used for ISM frequency band and to enhance the integration of sensors and circuits in UAV communication system. The paper presented the simulation and the measured results. This antenna Experimental results show the 3dB axial ratio bandwidth is 0.6%, the half power beamwidth is ±45º, and the gain is 4.5dBi. The antenna size reduction can be as large as 36%, as compared to that of the conventional CP design.

Abstract: This paper presents a physical channel emulator solution for applications such as Bit Error Rate Testing of Error Correcting Codes. The solution relies on an analog White Gaussian Noise Generator coupled additively with an analog data signal to emulate the communication channel. This is interfaced to a computer through a USB connection, allowing the use of programs in different environments, such as Matlab and Labview. This solution can allow different types of channels to be emulated and with different noise sources. A software-based method to measure Signal to Noise Ratio and to characterize the channel is also presented. The system has been validated using a Matlab interface implementing multiple error correcting codes and showed good agreement with the theoretical model.

Abstract: The current Internet addressing systems no longer adapt to the addressing mechanism of next generation network. This paper designed a Port Layer which was consist of Application Platform Interface Module, Resources Information Processing Module and Subnet Access Adapter Module to realize the connection of resource and the integration network of IPv6. The Port Layer addressing mechanism encoded resource in variable length with mixed classification, extended resource coding to 64-bit as the interface ID in the IPv6 address by automatically distributing the extension prefix, which is aim to supply dynamic addressing for mobile resource. This mechanism provides the theoretic foundation for the connection of the cyber world, the physical world and the cognition world.

Abstract: Network public opinion analysis, which is through the analysis of the situation of public opinion, can reflect the true society and public opinion, and on this basis, a reasonable forecast and recommendations decision-making can be provided for relevant managers. The paper studies on agricultural science and technology related website, and realize internet public opinion analysis for agriculture science and technology site. The network public opinion hotspots found technology is studied. It is achieved internet public opinion hotspots monitoring and found through the network information automatically grab and information classification. It is provided an analytical basis for managers to grasp the ideological trends in the network and make the correct guidance.

Abstract: The equipment, called detection platform of the cylinders, is used for detecting cylinders so that cylinders can be at ease use. In order to transmit the real-time detection data to PC for further processing, the platform should be connected with PC. Cable connection, in some production and environmental conditions, is limited. Under the circumstance, building wireless network is the better choice. Through comparative studying, ZigBee is chosen to be the technology for building wireless network. ZigBee chip and ZigBee2006 protocol stack are the core components in the ZigBee nodes.

Abstract: To achieve the security inte-gration of 3G and WAPI based WLAN, a USIM based certificate distribution protocol is proposed. Two security integration schemes, i.e, loosely coupled and tightly coupled, are presented, which unify user management of 3G security architecture and WAPI, and realize WAPI based network access for 3G subscribers and identity privacy protection. The entity authentication and anonymity of the certificate distribution protocol is analyzed in CK model, and the results show that the protocol is provably secure.

Abstract: A new structure of carrier recovery loop for high-order QAM is proposed in this paper, and applied in digital cable TV monitoring system. The structure operates in two modes with variable loop bandwidths, has the advantage of increasing convergence speed and minimizing the lock error, meanwhile, optimises the phase detection mode for the weighted DD algorithm to attain the fast recovery. Simulation results show that the algorithm is practicable and effective, and the carrier loop can capture up to 40% frequency offset of the symbol rate quickly and accurately.

Abstract: Considering the security demand of gathering and transporting coal bed methane in Shanxi Panhe area, integrated technologies of 3G wireless video monitoring system and 3S, developed emergency decision system for surface gathering and transporting of coal bed methane. Designed system architecture, function and database, finally, developed the system based on ArcGIS Engine in the .NET development environment, and realization methods of system’s key functions such as video monitoring, GPS monitoring, gas leakage simulation, fire simulation, debris flow simulation were discussed. Implemented remote monitoring and emergency command and dispatch through multi-source geo-spatial data, GPS information and video-audio messages, thus provided the intuitive basis for science decision-making, it is worthy to be popularized in emergency command area.