Aiming at the problems that the dimensions of vectors generated by Traditional Vector Space Model （TVSM） are high， and the vector dot product operation to calculate the correlation between the documents and the queried keywords is time-consuming， a Dictionary Partition Vector Space Model （DPVSM） for ciphertext ranked search in cloud environment was proposed. Firstly， the specific definition of DPVSM was given， and it was proved that the relevance score between the queried keywords and the documents in DPVSM was exactly the same as that in TVSM. Then， by adopting the equal-length dictionary partition method， an encrypted vector generation algorithm and a relevance score calculation algorithm between documents and queried keywords were proposed. Experimental results show that the space occupation of document vectors of DPVSM is much lower than that of TVSM， and the more the number of documents， the greater the occupation reduction. In addition， the space occupation of query vectors and the time consumption of relevance score calculation are also much lower than those of TVSM. Obviously， DPVSM is superior to TVSM in both the space efficiency of generated vectors and the efficiency cost of relevance score calculation.

To solve the detection problem of selfish behavior in IEEE802.15.4 Wireless Sensor Network (WSN), an improved Sliding Window Non-parameter Cumulation Sum (SWN-CUSUM) algorithm based on statistics was proposed to decrease the detection delay. By tracing the delay characteristic sequence between successful transmissions, the algorithm could distinguish if there was a selfish behavior in the WSNs. The NS2 simulation tool was conducted to validate the feasibility of the proposed algorithm. The experimental results show that the improved algorithm not only weakens the impact of the threshold on the performance of the algorithm, but also reduces the size of sliding window used to detect selfish behavior, and the improved algorithm makes improvement in the calculation and the detection delay than the primitive SWN-CUSUM algorithm, so the improved algorithm can detect effectively and rapidly the selfish behavior of nodes in IEEE802.15.4 WSNs.

After analyzing and researching the performance and deficiencies of TZSearch algorithm adopted by multi-view video, concerning the sequences of multi-view video obtained by parallel cameras, a new multi-view video coding optimization algorithm was put forward. The optimization was suggested mainly from the following three aspects: selection of search model, search strategy and adaptive threshold setting, so as to reduce the computational complexity of the algorithm. Tests were given on software testing platform for multi-view video named JMVC4.0. The experimental results show that: in ensuring the reconstruction video quality within tolerance, and under the premise of controlling the coding overhead, the optimized algorithm has reduced the average encoding time about 75% compared with the original algorithm, greatly improves the real-time performance of coding.