Applied Mechanics and Materials Vols. 347-350

Abstract: How to depend on different services provide different guarantee of QoS, and to ensure the effective use of network resources will become an important task in overlay network. In this paper, we consider constraints of network bandwidth, delay, loss rate, cost ,and base on the resources of current global network, as well as user-specific QoS metric needs to choose the best QoS route based on genetic algorithm. Experiments show that the algorithm is feasible in overlay network routing,and it has the better global load balancing capabilities.

Abstract: Along with the development of the network information age, people on the dependence of the computer network is more and more high, the computer network itself the security and reliability of becomes very important, the network management put forward higher request. This paper analyzes two algorithms of the network layer topology discovery based on the SNMP and ICMP protocol, based on this, this paper puts forward a improved algorithm of the comprehensive two algorithm, and makes the discovery process that has a simple, efficient, and has a strong generalization, and solved in the discovery process met the subnet judge, multiple access routers identification.

Abstract: In power system state estimation, bad data of local area can make state estimation difficult, and accuracy of measurement can also have great influence on the result of state estimation. Based on grid partition, this paper forms a lot of independent sub area, then measurement weights are adjusted using the state estimation result of sub area. This overcomes the defects of uniform weights distribution, and improves the accuracy of state estimation

Abstract: Network survivability has the characteristics of complexity, dynamic evolution and uncertainty, which has become one of the most important factors for analyzing and evaluating network performance. Network survivability analysis and evaluation is a process of analyzing and quantifying the degree to which network system can survive in network threats. This paper proposes a novel network survivability analysis and evaluation model.Firstly, network survivability is abstracted as a dynamic game process among network attacker, network defender and normal user, thereafter network survivability evolutionary game model is established and network survivability analysis algorithm is proposed based on the game model. Secondly, the survivability characteristics of the network can be measured and evaluated based on the analyzed information based on the proposed immune evolutionary algorithm for network survivability metric weight solving and network survivability evaluation method using multiple criteria decision making. Finally, the proposed network survivability analysis and evaluation model is experimented in a typical network environment and the correctness and effectiveness of the model is validated through experimental analysis.

Abstract: A single-chip solution is proposed to realize the node design based on 2.4 GHz ZigBee wireless sensor network. Mesh network topology is achieved by the use of ZigBee Pro protocol stack on the hardware platform. When the packets are successfully sent to the coordinator node, a relevant event will be generated by the local node. Hence, the parent node lost event can be obtained by comparing the number of the packets sent by the child node and the number of the packets sent successfully shown by the respond event. A wireless sensor network is designed to work independently from the coordinator node and can be re-connected according to the needed set to resume the network. When the coordinator node is taken away from the site or power down by happenstance and power up again after a long time, the parent lost event in the child nodes can make it rejoin the new coordinator node again when needed. The network self-healing function can be achieved by this mechanism that makes the network more stable.

Abstract: Allocated Spectrum band has always been a limited resource; being later a more challenging issue due to the growth of user demands. The past decade is marked by important changes in spectrum access through especially cognitive radio technology. Here, spectrum access issue can be studied in all the different aspects of cognitive capabilities. This paper focuses on spectrum handoff in spectrum mobility. We will then study secondary connections behaviors after multiple interruptions providing from multiple secondary connections. In the IEEE 802.22 standards [, two Spectrum Handoff Sequences have been defined to characterize Secondary Connections behaviors after each Primary Connections interruption. These sequences are known as always-leaving and always-staying sequences. A recent analysis uses the extended data delivery time metric to analyze these Spectrum Handoff Sequences. It shows the exponential value of connections service time in the first sequence (always-leaving sequence) and in the other (always-staying sequence), the lack of fairness due to the acquisition of channels low-priority queue by the ongoing secondary connection (i.e. the secondary connection actually being served in the low-priority queue). Weve also noticed that the Extended Data Delivery Time is a good but limited metric because of the lack of prevision, which is a quality needed in cognitive radio networks, especially when implementing spectrum handoff sequences. Our present study aims to analyze these limitations. In what follows, we use the PRP M/G/1 queuing model in cognitive radio network to evaluate latency-sensitive traffic of Secondary Connections through a novel performance metric that we name Lifetime of Secondary Connections.

Abstract: Node failure is an important factor causing network faults. Through research on node failures, mastering the effect laws of failure is a reasonable and effective method to improve network reliability. This paper summarized and classified the node failure modes of communication network. Meanwhile, combined with the classic BA network model in complex network theory, the effect laws of nodes function failure and performance failure on network reliability were investigated with the design of simulations using MATLAB and OPNET. The results have great guidance value for the simulation of network reliability and network reliability design under limited operation cost.

Abstract: Communication is the basic method to guarantee oil transportation command and scheduling of mobile long-distance pipeline and is the nervous system of the mobile pipeline. Based on the characteristics such as varied topography of the region it extends, long distance between stations, large volume of data transmitted and high requirement for security and relying on the private network of Telecom CDMA VPDN, the wireless data communication system for pipeline patrol integrating task management, service filing, real-time communication and positioning & navigation is established. The experiment proves that the system establishes safe and reliable real-time communication and achieves desired effects and smooth high-efficient upstream & downstream data transmission. It is of significance to improve patrol efficiency and quality and to guarantee oil transportation security of the pipeline.

Abstract: Multicast address allocation is a key and difficult points of HLA simulation system. Multicast address allocation need to select or improve according to the actual application needs. In the data distribution management based HLA simulation grid, for the contradiction of redundant data receives and multicast address demand , we put forward a multicast address allocation of HLA hierarchy structure and described the data forwarding algorithm. Within the site, multicast address allocation use the method based on the data receiver and forwarding server contains a filter allocation table based on the receiver's multicast address.When there is a data access, RTIA according to assign tables to forward the data to the appropriate multicast addresses. Using this method, you can avoid node receives data not related to.The simulation experiment and results analysis show that: the maximum level of nodes in the multicast reception of the message overhead can be significantly enhanced; using the hierarchical multicast routing aggregation, and based on the aggregation of routing information that is both feasible and effective.

Abstract: A security node-based key management protocol is proposed for cluster-based sensor networks. Member nodes and cluster heads are responsible for data collection and transmission. Security nodes are responsible for key management. Security nodes restrain key management function of cluster heads, and reduce damage of captured cluster heads. Generation of security nodes and different kinds of keys is described. Performance analysis and simulation show that the proposed key management protocol consumes less energy, and its delay time of key generation is short. At the same time, the protocol can provide more collaborative authentication security for keys. It has strong resilience against node capture, and can support large scale network.