Applied Mechanics and Materials Vol. 577

Abstract: Digitizing architecture of band-pass sampling at IF(Intermediate Frequency) is a kind of software radio structure of high practical value. One kind of application in the digitizing architecture of band-pass sampling at IF of RF (Radio Frequency) front-end hardware is designed in this paper. The experimental results show that this kind of RF front-end has great practical value and research significance.

Abstract: Due to the fact that the wireless spectrum is limited but the wireless demand can grow unlimited, how to improve the wireless capacity becomes one of the hot topics in wireless network field. In this paper, we focus on the scenario of busy wireless environment, and present a protocol with multiple user beamforming. The protocol enables a network to scale its uplink throughput with the number of access points. Theoretical and experimental results show that our protocol have higher uplink throughput compared with 802.11. Moreover, our protocol is the first method that shows that linear scaling of uplink throughput with the number of access points is possible.

Abstract: Mobile communication has gone through two generation of development, now the third generation mobile communication technology has been mature and widely used. Achieving the third generation mobile communication technology is intended to give users a better mobile voice call quality, faster mobile data speeds and more multimedia services, to attain large capacity and high spectral efficiency. W-CDMA, one of the three mainstream standard of international third generation mobile communication technology, is based on the foundation of GSM/GPRS and evolve. This paper describes the 3GPP core technology, which is based on W-CDMA, and using ADS to complete the simulation of W-CDMA/3GPP communication system.

Abstract: The RFID back-end system is the core of the thing of networking technical framework, and it has suffered more security threats. In the face of these security problems in the backend system, this paper design a node bidirectional authentication and key exchange protocol based on certificate and ECDH(SRCE), to guarantee the safety of the RFID backend systems. The analysis result indicates that the protocol obtain smaller key sizes and higher computational efficiency on the performance, furthermore, there are many security properties in which, such as data confidentiality, mutual entity authentication, against known key attack, etc.

Abstract: Optimal controlled splitting is an emergency strategy to split the power system into several sub-regions based on global electrical information before the collapse of the system which is subject to severe disturbances. How to seek the optimal splitting sections rapidly and accurately is a key problem in controlled splitting field. A controlled splitting scheme based on layer expanding graph algorithm is presented in this paper. Firstly, source nodes of island regions extend out for the formation of the island regions. Secondly, island regions can be combined to make up synchronous sub-regions on the basis of the clustering of generators. At last, the optimal sections can be determined according to the initial and improved adjustment of splitting sections. Moreover, the scheme proposed can be adapt to the change of operation mode of the power system. The accuracy and effectiveness of the scheme is shown by the simulation results of CEPRI 36-bus system.

Abstract: In the experiment and training of electronic information equipments under the complex electromagnetic environment, the mutual interference problem among equipments with different frequency is a difficult problem which influences the effect evaluation. On the basis of the analysis of the mutual interference mechanism, this paper analyzes the influence of the scattered signal, harmonic signal and intermodulation mutual interference signal through tremendous tests and has come to certain conclusion.

Abstract: Based on CREO Parametric 2.0, programmed by Pro/TOOLKIT and used Visual Studio as a developing platform, the virtually loaded path-planning module targets the dismantlement of tooling spring pin as an investigated object, thus enhancing the efficiency of virtual device significantly.

Abstract: Wireless communication can provide ubiquitous access to the Internet and more convenience than wired communication. Due to the wide open nature of wireless radio, security over a wireless environment is more complicated. From the initial IEEE 802.11 to IEEE 802.11i, more robust security methods have been adopted to eliminate underlying attacks. IEEE 802.11i is based on the assumption that all participants are honest that they will act as they are expected. But usually it is not true. How to recognize a genuine user, how to keep authentication data safely, and how to prevent dishonest supplicant accessing WLAN are big challenges. Trusted Computing can be used to improve security status of endpoint. Applying Trusted Computing technology can solve these challenges and enhance WLAN security.

Abstract: In order to find out the specific location algorithm suitable for the underground mine and how to realize the applications of the node location.This article through the setting two different coal mine environment (i.e. roadway environment and underground environment of coal mine) from different aspects carry out simulation analysis to four location performance based on range-free algorithm, use the expansion and modeling NS2 simulation platform, obtain the important conclusion: centroid algorithm is the most suitable for long and narrow roadway simulation environment, and DV-Hop is the most suitable for the underground intensive environment of the unknown nodes high density and less beacon nodes.

Abstract: Automatic Dependent Surveillance Broadcast (ADS-B) system signal error detection and correction process scheme are introduced in this paper, and the working principle of cyclic redundancy check (CRC) is described. Then, this paper provides an error correction algorithm based on the confidence judgment and an error correction process flow chart based on ADS-B system. Finally, the design of CRC checksum is performed by taking use of Verilog HDL, and the simulation and verification are achieved in Modelism software platform. Experimental results show that the algorithm can carry out verification and error correction for ADS-B responding signal and can improve the reliability of ADS-B system signal transmission.