We investigate the timestamp allocation scheme in classical concurrency controls of the database management systems (DBMS) on many-core machines. Then we discuss a distributed logical timestamp allocation scheme with uniqueness and fairness to improve the performance of DBMS concurrency control algorithms on many-core machines. Further, the proposed logical timestamp generator is free of bottlenecks such as accessing the system clock counter, calling for atomic add operation, and synchronization. Finally, we experiment with an optimistic concurrency control algorithm based on the proposed and other allocation schemes. The results show that the performance of an optimistic concurrency control algorithm based on the proposed timestamp allocation outperforms one based on other allocations. Furthermore, it has better linear scalability under heavy loads.

For any bent function, it is very interesting to determine its dual function, because the dual function is also bent in certain cases. For k odd and gcd(n, k) = 1, it is known that the Coulter-Matthews bent function f(x) = T r (ax 3k+1/2) is weakly regular bent over F3n, where a ∈ F3n*, and T r (·) : F3n→ F3is the trace function. In this paper, we investigate the dual function of f (x), aiming to determine a universal formula. In particular, for two cases, we determine the formula explicitly: for the case of n = 3t + 1 and k = 2t + 1 with t ≥ 2, the dual function is given by Tr (- x32t+1+3t+1+2/a32t+1+3t+1+1) - x32t+1/a-32t+3t+1+ x2/a-32t+1+3t+1+1); and for the case of n = 3t + 2 and k = 2t + 1 with t≥2,the dual function is given by Tr (-x32t+2+1/a32t+2-3t+1+3- x2.32t+1+3t+1+1/a32t+2+3t+1+3+ x2/a-32t+2+3t+1+3) As a byproduct, we find two new classes of ternary bent functions with only three terms. Moreover, we also prove that in certain cases f (x) is regular bent.

Personal context information is important to enable context-aware applications in pervasive spaces. As privacy, many investigators have pointed out that it must be in the controllable state by using personal privacy policy. The long term objective of this research was to extract privacy policy from personal context information database with machine learning method. A context-aware telephone system was designed to collect data, learn policy and examine the accuracy of policy. In the step of PDA simulation, the results showed that the method was possible to make suitable decision for telephone communication in consideration of privacy protection. In order to further validate the proposed privacy protection method, the pervasive space was designed and implemented to get more real data about using context-aware telephone. At the step of pervasive space simulation, we design and code the prototype of context-aware telephone system from the view of software engineering.

By using personal information in a pervasive computing environment, context-aware applications can provide appropriate services for people. This personal information is often involved in personal privacy. In order to protect personal privacy concerns about personal information, privacy role is proposed to control access personal information. We also construct an information system about the privacy decision of personal information disclosure based on people's interaction history. In the initial period of personal information disclosure, the privacy decision is made by people and the information system is constructed based on the decision data. Then privacy disclosure policies are extracted from this information system using rough set theory. According to deducing from the privacy disclosure policies and people's context information, the contextaware application is assigned to an adequate privacy role. It reduces the distraction of privacy decision for people. A case study further shows the proposed method is effective. Finally, it provides about the overload performance of privacy role analysis personaengine.

In pervasive environment, context-aware service provider can use personal information to customize the adequate services for end users. Personal information is people's privacy concern. Therefore, people need privacy control methods. In this paper, we analyzed privacy control from two aspects: personal privacy model about information disclosure and the function of context-aware service provider. According to the analysis, we designed the components about context-aware privacy control in order to minimize the burden of personal privacy decision about personal information disclosure. The simulation experiment shows that it is possible method for the proposed privacy protection mechanism. Finally, we also proposed conceptual context-aware architecture to control personal information disclosure.