In order to overcome the problems of low convergence precision and easily relapsing into local optimum in Fruit fly Optimization Algorithm (FOA), by introducing the Levy flight strategy into the FOA, an improved FOA called double subgroups FOA with the characteristics of Levy flight (LFOA) was proposed. Firstly, the fruit fly group was dynamically divided into two subgroups (advanced subgroup and drawback subgroup) whose centers separately were the best individual and the worst individual in contemporary group according to its own evolutionary level. Secondly, a global search was made for drawback subgroup with the guidance of the best individual, and a finely local search was made for advanced subgroup by doing Levy flight around the best individual, so that not only both the global and local search ability balanced, but also the occasionally long distance jump of Levy flight could be used to help the fruit fly jump out of local optimum. Finally, two subgroups exchange information by updating the overall optimum and recombining the subgroups. The experiment results of 6 typical functions show that the new method has the advantages of better global searching ability, faster convergence and more precise convergence.
In the research and application of multi-cross channel model, to maximize fault recovery of individual channel is the basis of the correctness to vote. There is some time redundancy in a task period. For a task processing in a given step, to summarize the time redundancy of pre-voting step, and assume fault-free on succedent step, then there will be a time redundancy on succedent step. The redundancy time of previous and succedent steps was counted, then a superior time window was used to do more deep recovery of fault. Based on the above ideas, a dynamic time series of multi-cross channel model was proposed, which was analyzed for deep recovery, and a backward recovery algorithm was given, which endowed more time to the fault unit, then the instantaneous fault could be eliminated to the utmost. Moreover, a monitoring logic was put forward to support the recovery algorithm. Theoretical analysis and experiments show that the backward recovery algorithm is effective to enhance the recovery rate and to reduce in the number of steps falling out. Compared with the statical recovery, the recovery rate increased by 47.49% and 72.35% respectively, and the number of out of step decreased by 58% and 85% respectively in the condition of 4 channel and 6 channel, which boosts the reliability of multi-cross channel model, especial in the condition of a large number of voting steps.
In traditional Proxy Re-Encryption (PRE), a proxy is too powerful as it has the ability to re-encrypt all delegator's ciphertexts to delegatee once the re-encryption key is obtained; And for more than one delegatees, delegator needs to generate different re-encryption key for different delegatee, which wastes a lot of resources in the calculation process. To solve these problems, an identity-based conditional proxy broadcast re-encryption was introduced. The delegator generated a re-encryption key for some specified condition during the encryption, like that the re-encryption authority of the proxy was restricted to that condition only. Moreover, the delegator's ciphertexts could be re-broadcasted to ensure the important communication and save a lot of computation and communication cost. Finally, the theoretical analysis verified the security of the scheme.
With the development of programming technology and theory, some problems in practice, which can not be solved by the traditional OO theory, are attracting more and more interests of researchers. A generative programming-based approach was proposed to solve such kind of problems by constructing domain-neutral models and low-coupling modules. One implementation of our proposed approach, AOP, was analyzed to demonstrate the advantages and shortcomings of our approach. Finally, a comparison between AOP-based and OO-based Observer models was conducted to show the superiority of our approach over traditional OO approaches.