Aiming at the problem of data sparsity, poor portability and lack of recognition of multiple words (more than three words) in micro-blog new word discovery algorithm, a new word discovery algorithm based on improved Mutual Information (MI) and Branch Entropy (BE), named MBN-Gram, was proposed. Firstly, the N-Gram was used to extract the candidate terms of new words, and the rules of using frequency and stop words were used to filter the candidates. Then the improved MI and BE were used to expand and filter the candidates again. Finally, the corresponding dictionary was used to screen, so as to get new words. Theoretical and experimental analysis show that the accuracy rate, recall rate and F value of MBN-Gram algorithm were improved. Experimental results shows that the MBN-Gram algorithm is effective and feasible.

There exists the problem of security insufficience among the data privacy protecting technology which is the privacy leakage caused by homogeneity and background knowledge attack when computing equivalence classes in the anonymity process. To solve the problem, an anonymized data privacy protection method based on differential privacy was put forward, and its model was constructed. ε-MDAV (Maximum Distance to Average Vector) algorithm was presented, in which micro-aggregation MDAV algorithm was used to partition similar equivalence classes, and SuLQ frame framework was introduced into the anonymous attribute process. Laplace mechanism was used to reasonably control the privacy protection budget. The comparison of availability and security under different privacy protect budgets verifies that the proposed method effectively improve data security while guaranteeing high data availability.