Applied Mechanics and Materials Vols. 427-429

Abstract: Software aging threatens to the reliability of the software and computer system seriously, and has become the main bottleneck restricting the development of software reliability. As most of user behavior has certain regularity, so it can be forecast. This paper proposed a prediction method based on the Frequent-User-Access-Patterns-Tree-With-Time-And-Aging (FUAP-Tree). And this method compressed the user behavior into a FUAP-Tree to store the Web log, and then predicted the user behavior using pattern matching by traversing the sub-trees of the FUAP-Tree. The load of the Web application software could be obtained when user behavior is known. So we could predict the Web application software aging. The conclusion we got by the experiment of comparing with another method is that this method got a more effective and accurate result.

Abstract: In cognitive networks, the existing RASR routing algorithm does not consider channel usage ratio of the PU and results in an unstable path problem. To address these issues, a new Routing Selection Algorithm in Cognitive mesh networks (RSAC) is proposed in this paper. RSAC is designed by piggybacking the information of link stability factor which is the sum of the channel usage ratio of secondary users and choosing routes based on it. It enhances the route stability, improving the success ratio of data packets transmission, reducing the average end-to-end delay. Theoretical analysis and simulation results show that RSAC outperforms the RASR routing algorithm in terms of the success ratio of data packets transmission, the average end-to-end delay.

Abstract: The bottleneck is not the disk I/O but CUP clock speed faster than the memory speed in main memory database .In order to achieve high performance in main memory database ,it is a good approach to design new index structures to improve the memory access speed .This chapter presents a T-tree index structure and its algorithms in main memory database firstly .Then presents two results on Optimization of T-tree index ,including T-tail tree and TTB-tree. Our results indicate that the T-Tree provides good overall performance in main memory.

Abstract: Formal context is one of the research contents of formal concept analysis theory. In concept lattice, the attributes of the object are equivalent and there is no hierarchy. Facing to this problem, the equivalence relation which is on the attributes' set is defined and the corresponding σ operation is proposed. On this basis, the structure method of attribute hierarchical diagram is presented and attributes' sequences of associated objects are obtained. This conclusion enriches and extends the analysis method of the formal context.

Abstract: Localization is one of the key technologies of wireless sensor networks, and the problem of localization is always formulated as an optimization problem. Particle swarm optimization (PSO) is easy to implement and requires moderate computing resources, which is feasible for localization of sensor networks. To improve the efficiency and precision of PSO-based localization methods, this paper proposes a novel three-dimensional PSO method based on weight selection (WSPSO). Simulation results show that the proposed method outperforms standard PSO and existing localization algorithms.

Abstract: For random distribution of large-scale wireless sensor network (WSN), the hexagonal distributed cluster-based multi-hop routing protocol based on event triggering (HDCMET) is proposed. Triggered by events, nodes optimize a cluster head, according to the rest energy. A cluster head chooses other nodes for a hexagon, with distance to the cluster, energy and so on. Simulation results show that this protocol prolongs the network life in total, improving the network performance in large-scale WSN, compared with the low energy adaptive cluster hierarchy (LEACH).

Abstract: This paper gives an improved negative binomial approximation for negative hypergeometric probability. Some numerical examples are presented to illustrate that in most practical cases the effect of our approximation is almost uniformly better than the negative binomial approximation.

Abstract: With the popularity of location-based services, Web contents are being geo-tagged and spatial keyword queries that retrieve objects satisfying both spatial and keyword conditions are gaining in prevalence. The existing spatial keyword queries focus on exact match or prefix match of the keywords cannot satisfy the demand of wildcard based imprecise match in many realistic scenes. Aiming to solve this problem, two methods which are fit for different situation are put forward: the inverted file and R-tree integrated index which fits for the situation that requires high time efficiency and the Prefix Bloom Filter and R-tree integrated index which fits for the situation requiring high space efficiency. The effectiveness of the two indexes is valid through experiments.

Abstract: Modulation and demodulation are two important parts in BAN baseband transmission systems. Different demodulation algorithms may affect the BER performance of the entire system seriously. Referring to IEEE 802.15.6 BAN standard, theoretical analysis and algorithm design of the modulation and demodulation for π/2-DBPSK and π/4-DQPSK is carried out and simulation results of BER performance are presented in this paper. In AWGN channel, both modulations achieve good performance, and performance degradation of π/4-DQPSK happens in multipath channel which may not satisfy the requirements. Adaptive modulation is considered to solve this problem by choosing different modulation scheme according to channel quality.

Abstract: This paper is based on my master's degree thesis, here we use the optimal algorithm for attribute reduction -- improvement on Property resolution of Reduction Arithmetic, this algorithm is applying to complete and incomplete information system.