Applied Mechanics and Materials Vols. 241-244

Abstract: Network security is one of the most important issues in the face of Internet development. Major researches are done on improving the current status of the security of internet. This article describes some major factors threatening internet, and analysis the latest security techniques. corresponding strategies are proposed to achieve a safe, worry-free environment online.

Abstract: In this article, studying the integration relations between mobile network and DECT technology, a design scheme about Voice Gateway System is introduced. This system builds a small voice network, providing shared multi-parities talking service, for home and office.

Abstract: With many periodical discontinuous boundaries, periodic tube structure is prone to inter-symbol interference in acoustic communication. To look for the appropriate communication method and improve the quality of acoustic communication in the structure, experiments were carried out in the real periodic structure using raised cosine ASK, FSK and BPSK modulation respectively. The results show that：in periodic tube structure, ASK, FSK, and BPSK all can realize normal acoustic communication in the condition without noise or the noise is weak. Raised cosine ASK modulation can better use transmission power and get the highest data rate (up to 65.7Kbps in the experimental structure) in un-noise environment. BPSK has the best noise immunity in the condition with noise. So, the BPSK is more suitable for the actual acoustic communication in periodic tube structure in the actual environment.

Abstract: For the congestion problems in high-speed networks, a Metropolis criterion based fuzzy Q-learning flow controller is proposed. Because of the uncertainties and highly time-varying, it is not easy to accurately obtain the complete information. In this case, the Q-learning, which is independent of mathematic model, and prior-knowledge, has good performance. The fuzzy inference and Metropolis criterion are introduced in order to facilitate generalization in large state space and balance exploration and exploitation in action selection individually. Simulation results show that the controller can learn to take the best action to regulate source flow with the features of high throughput and low packet loss ratio, and can avoid the occurrence of congestion effectively.

Abstract: Radio frequency identification (RFID) systems need security protocols to provide confidentiality, user privacy, mutual authentication and etc. This paper analyze two of the newest RFID security protocols which proposed by Niu et al. and Fu et al. form the security viewpoint of data desynchronization attack. These two lightweight protocols were expected to proposed security protections for the RFID system and safeguard against almost all major attacks. However, we found that these two RFID security protocols were vulnerable to the attack of data desynchronization. Based on strand space model, data desynchronization attacks on these two protocols were analyzed. Furthermore, improvements to overcome the security vulnerabilities of these two protocols were given.

Abstract: Evaluating risk effectively selecting effective defence measures and defending information threats actively are the key points of resolving security problems of information system．Based on the actual requirements and status of risk assessment of information security，we integrate attack graph to apply it in studying risk assessment of information security．Firstly，focused on the uncertainty and complexity of risk assessment of information security，we integrate the technology of vulnerabilities associated with to apply it in studying risk assessment．On the other hand，since the attack path described by attack graph model is suited for the quantity data processing，and poor to the qualitative analyze，and risk is uncertain，the risk factors are quantized by the probability of attack path forming proposed in this dissertation so that the probability of atom attack are pre-treated，a risk assessment method based on attack graph model is proposed．The method Take full advantage of computing power of each host in the network, greatly shorten the attack graph generation time.

Abstract: Vehicular ad-hoc Networks (VANETs) has become a hot topic in recent years, where the routing protocol has also become research focus. The vast majority of the existing routing protocols are designed for a single scenario, thus it is difficult for them to be extended for the complicated traffic environment. In this paper we propose a new routing algorithm X-CAST for vehicular communication on highway, which can be adaptive to different phases of traffic flow and guarantee reliable transmission in different environments. The experimental results reveal that X-CAST performs much better than other traditional routing protocols in complex traffic flow situation.

Abstract: This paper presents a design of instrument management systems based on the wireless HART communications technology. The whole system achieves data of intelligent HART instrumentation uploading and setting through the wireless HART communication network. Data server software parses the data according to the wireless HART data frame format, and saves data through the real-time historical database of SCADA software Force Control 6.1. Application server provides a visual user interface, completes the configuration and monitoring for the field intelligent instrument and operates easily. This system has the scalability, reconfigurability, and other characteristics and it has a certain application value on the HART intelligent instruments of information management.

Abstract: Real-time video transmission demands tremendous bandwidth, throughput and strict delay. For transmitting real-time video in the multi-interface multi-channel Ad hoc, firstly, we applied multi-interface multi-channel extension methods to the AOMDV (Ad-hoc On-demand Multipath Distance Vector) routing protocol, and improved extant channel switching algorithm, called MIMC-AOMDV (Multi-Interface Multi-Channel AOMDV) routing protocol. Secondly, we proposed video streaming delay QoS(Quality of Service) constraint and link-quality metrics, which used the multi interface queue’s total used length to get QMMIMC-AOMDV (Quality metric MIMC -AOMDV) routing protocol. The simulations show that the proposed QMMIMC-AOMDV can reduce the frame delay effectively and raise frame decodable rate and peak signal to noise ratio (PSNR), it is more suitable for real-time video streams.

Abstract: Steam generation and injection in thermal recovery station constitute a very complicated HPHT system, mainly including power supply, water supply and treatment, fuel oil or gas regulation, steam and gas separation, safety and protection etc. To ensure normal operation of the system and realize centralized intelligent management and control, Modbus communication technology is used for configuration and connection of hardware and selection of software. The result shows that sub-systems of steam injection station such as intelligent power supply etc are well integrated.