Concerning the tedious process during the construction of concept lattice, to improve the efficiency of building concept lattices, a new incremental method of constructing concept lattice based on intent waned value by seeking top elements was proposed. Firstly, top element, original concept, produced concept, new concept, producer concept, the set of intent waned values, reminded parent concept, superset delete and regular queue were formally defined; the judging theorem and proof whether the concept elements were top elements were given. Secondly, the elements were extracted from the regular queue of the original lattice in due order and the reminded parent concepts were got after superset delete. Finally, the top elements were found from the equivalent classes of the reminded parent concepts and the regular queue of the new lattice was gradually generated. Time complexity was effectively reduced compared with the Attribute-based Concept Lattice Incremental Formation (CLIF-A) algorithm and the FastAddIntent algorithm by theory analysis. In comparison with simulated experiments, the time consumption of the proposed algorithm was far less than the comparative approaches in large size of population. The simulation results show that the proposed algorithm is simple, and can effectively improve the time performance, meanwhile provides better performance in construction efficiency.

Concerning the problem that it is difficult for the users in cloud computing to obtain the high-quality and personalized cloud services provided by a large number of cloud providers, a trust model based on user types and privacy protection for the personalized cloud services was proposed. Firstly, the users were divided into familiar users, strange users and normal users according to the transaction history. Secondly, a fair and reasonable trust evaluation Agent was introduced to protect users' privacy, which could evaluate the trust relationship between requesters and providers based on the user types. Lastly, in view of the dynamics of trust, a new updating mechanism combined with the transaction time and transaction amount was provided based on Quality of Service (QoS). The simulation results show that the proposed model has higher transaction success rate than AARep and PeerTrust. The transaction success rate can be increased by 10% and 16% in the harsh environment where the malicious user ratio reaches 70%. This method can improve transaction success rate, and has a strong ability to withstand harsh environments.