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High utility itemset mining algorithm based on Markov optimization
Xincheng ZHONG, Chang LIU, Xiumei ZHAO
Journal of Computer Applications    2023, 43 (12): 3764-3771.   DOI: 10.11772/j.issn.1001-9081.2022121844
Abstract200)   HTML3)    PDF (1476KB)(96)       Save

To address the problems that the High Utility Itemset Mining (HUIM) algorithms based on tree and link table structures often consume search spaces of orders of magnitude, and the evolutionary type-based mining algorithms fail to fully consider the interactions between variables, an HUIM algorithm based on Markov Optimization (HUIM-MOA) was proposed. Firstly, a bitmap matrix for expressing database and expectation vector encoding were used to achieve fast scanning of the database and efficient computation of utility values, respectively. Then, the Markov Network (MN) structure was estimated by computing the mutual information among dominant individuals and new populations were generated by using Gibbs sampling according to their local characteristics. Finally, population diversity preservation strategy and elite strategy were used to prevent the algorithm from falling into local optimum too quickly and to reduce the missing of high utility itemsets, respectively. Experimental results on real datasets show that compared with Bio-inspired High Utility Itemset Framework based on Particle Swarm Optimization (Bio-HUIF-PSO) algorithm, HUIM-MOA can find all the High Utility Itemsets (HUIs) when given a larger minimum threshold, with on average 12.5% improvement in convergence speed, 2.85 percentage point improvement in mined HUI number, and 14.6% reduction in running time. It can be seen that HUIM-MOA has stronger search performance than the evolutionary HUIM algorithm, which can effectively reduce the search time and improve the search quality.

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Security analysis and improvement of KNXnet/IP protocol
Jun-chang LIU Xi-huang ZHANG
Journal of Computer Applications    2011, 31 (07): 1912-1916.   DOI: 10.3724/SP.J.1087.2011.01912
Abstract1723)      PDF (871KB)(901)       Save
As the extended application of European Installation Bus (EIB) protocol, KNXnet/IP protocol increases the transmission speed of EIB system and fulfills the requirement of intelligent management. But the security of KNXnet/IP protocol is heavily threatened in the securitycritical environment. A security protocol was proposed after analyzing the security mechanism of IP network and embedded system. The security protocol used selfdefined key sets distribution protocol based on asymmetric cryptography algorithm and used symmetric cryptography algorithm for communication. It provides transparent data transmission and only needs very few changes of the primary architecture. The implementation proves the feasibility and security of the security approach.
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