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High-performance regular expressions matching algorithm based on improved FPGA circuit
ZHUO Yannan, LIU Qiang, JIANG Lei, DAI Qiong
Journal of Computer Applications    2016, 36 (4): 927-930.   DOI: 10.11772/j.issn.1001-9081.2016.04.0927
Abstract600)      PDF (563KB)(410)       Save
Concerning the low throughput and too much logic resource usage in the process of regular expressions matching, an improved Deterministic Finite Automaton (DFA) regular expression matching algorithm fully based on Field-Programmable Gate Array (FPGA) logic circuit was designed. Firstly, the result that most transfer edges of each state in DFA would point intensively to the same state characteristics was counted; then an acquiescent transfer edge for each state setting in DFA was provided according to the transfer matrix of regular expressions; finally, simplified logical circuit was given, and measurement was conducted on the L7-filter rule set. The experimental result shows that, compared with the former Nondeterministic Finite Automaton (NFA) algorithm, 10%-60% rules get a higher throughput, and 62%-87% rules cost less logic resources.
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Research and implementation of WLAN centralized management system based on control and provisioning of wireless access points protocol
LIU Qian HU Zhikun LIAO Beiping LIAO Yuanqin GUO Hailiang
Journal of Computer Applications    2014, 34 (3): 635-639.   DOI: 10.11772/j.issn.1001-9081.2014.03.0635
Abstract571)      PDF (751KB)(458)       Save

In view of maintenance difficulties and high cost in large-scale development of Wireless Local Access Network (WLAN), the Control and Provisioning of Wireless Access Points (CAPWAP) protocol that applied to communication between Access Controller (AC) and Wireless Terminator Point (WTP) was researched and implemented. In Linux environment, main features were realized, such as state machine management, and WTP centralized configuration. A platform of WLAN centralized management system based on local Medium Access Control (MAC) framework was built up. Wireshark capture tool, Chariot and Iperf were used to test the platform. The capture test results verify the feasibility of the framework, and the results of throughput and User Datagram Protocol (UDP) test also show that network performance is efficient and stable.

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Three dimensional reconstruction algorithm based on uncalibrated multiple images
ZHAO Lu-lu GENG Guo-hua WANG Xiao-feng LIU Qian
Journal of Computer Applications    2012, 32 (10): 2802-2805.   DOI: 10.3724/SP.J.1087.2012.02802
Abstract972)      PDF (636KB)(437)       Save
This paper proposed an algorithm for 3D reconstruction based on uncalibrated images. First, this algorithm detected the feature points by using Harris corners, and presented an improved bidirectional matching to match these feature points. Under the condition of the known camera parameters, the authors carried out 3D reconstruction of two images. Then the quaternion algorithm was adopted to transform coordinate. The results coming from different subsets were brought into a common coordinate frame, achieving 3D reconstruction of multiple images. Finally, bundle adjustment was used to optimize the results. The experimental results show that object structure can be well reconstructed by using this algorithm.
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Optimal deployment of multiple sink nodes in wireless sensor networks
LIU Qiang MAO Yu-ming LENG Su-peng LI Long-jiang ZHUANG Yi-qun
Journal of Computer Applications    2011, 31 (09): 2313-2316.   DOI: 10.3724/SP.J.1087.2011.02313
Abstract1633)      PDF (647KB)(490)       Save
In a large-scale Wireless Sensor Network (WSN), the nodes closer to the single sink node use up their energy more quickly than others because of relaying more packets so that the network is invalid rapidly. In order to elongate the network lifetime, it is required to deduce the hops from sensor node to sink node. An efficient method is to deploy multiple sink nodes instead of single one. Therefore, it needs to be considered that how many sink nodes should be deployed on minimizing network cost and maximizing network lifetime. A network lifetime model and a cost model were proposed in WSN with multiple sink nodes and a new method was presented to determine the optimal number of sink nodes by computing the Ratio of Lifetime to Cost (RLC). The theoretical studies show that the number of sink nodes is related to the cost of sensor nodes and sink nodes, the network scale, the number of critical sensor nodes and the transmission power of sensor node. The simulation results prove the theoretical conclusion.
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DVB-CI device driver development on embedded Linux system
ZHOU Qing-xi,LIU Qiang
Journal of Computer Applications    2005, 25 (07): 1698-1700.   DOI: 10.3724/SP.J.2005.01698
Abstract946)      PDF (418KB)(772)       Save

The method was introduced to encapsulate the detailed controls of the concrete DVB-CI device with device driver and provide the uplayer program an abstract device on the embedded Linux system. A DVB-CI device driver based on MontaVista's Hard Hat Linux system and IBM STB02500 Set-Top Box Integrated Controller was implemented as an example.

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Design and implementation of development framework for human-oriented workflow management system
ZHOU Yao-yu, LIU Qiang, ZHAO Ming-yang
Journal of Computer Applications    2005, 25 (07): 1670-1673.   DOI: 10.3724/SP.J.1087.2005.01670
Abstract935)      PDF (536KB)(683)       Save

A development framework for human-oriented workflow management system was designed and implemented. A case of specific scenario using this developement framework was given. The framework was divided into three layers, business object layer, runtime layer, and business entity layer. Business object layer provided efficient and concise API; Runtime layer set up a manageable runtime environment to make application run reliably; Business entity layer stored and maintained business object. Developing application with the framework will decrease the development complexity and make system maintain easier.

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