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Design of fault-tolerant router for virtual channel dynamic allocation based on port fault granularity partition
HANG Yanxi, XU Jinfu, NAN Longmei, GUO Pengfei
Journal of Computer Applications    2017, 37 (6): 1560-1568.   DOI: 10.11772/j.issn.1001-9081.2017.06.1560
Abstract461)      PDF (1275KB)(482)       Save
High reliability is an important issue in the development of high performance network-on-chip router. Concerning the problem that the ports of the router whose virtual channel is dynamic allocated are prone to fail at present, a design of fault-tolerant router based on port fault granularity partition was proposed. Firstly, a fault and congestion model for ports based on granularity partition was established combining with the specialty of the virtual channel dynamic allocation and faults' characteristics. Then, the related fault-tolerant circuit was designed on the basis of the model combining with the real-time fault detection methods, an adjacent port sharing module was added and a fault-tolerant read/write point control logic circuit was designed. Finally, a fault-tolerant and congestion mitigation scheme was put forward based on the design. The experiments shows that the proposed router can maintain fault tolerant properties under various port failure modes with little performance degradation, and it has high ratio of performance improvement and area overhead.
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Dynamic sampling method for wireless sensor network based on compressive sensing
SONG Yang, HUANG Zhiqing, ZHANG Yanxin, LI Mengjia
Journal of Computer Applications    2017, 37 (1): 183-187.   DOI: 10.11772/j.issn.1001-9081.2017.01.0183
Abstract639)      PDF (948KB)(437)       Save
It is hard to obtain a satisfactory reconstructive quality while compressing time-varying signals monitored by Wireless Sensor Network (WSN) using Compressive Sensing (CS), therefore a novel dynamic sampling method based on data prediction and sampling rate feedback control was proposed. Firstly, the sink node acquired the changing trend by analyzing the liner degree differences between current reconstructed data and last reconstructed data. Then the sink node calculated the suitable sampling rate according to the changing trend and fed back the result to sensors to dynamically adjust their sampling process. The experimental results show that the proposed dynamic sampling method can acquire higher reconstructed data accuracy than the CS data gathering method based on static sampling rate for WSN.
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Proportional delay guarantee on Web server based on decentralized self-tuning control
GUO Guang ZHANG Yanxin
Journal of Computer Applications    2014, 34 (4): 973-976.   DOI: 10.11772/j.issn.1001-9081.2014.04.0973
Abstract473)      PDF (577KB)(497)       Save

Single-variable model is generally used for Apache Web server. It has poor scalability when it is used to handle multiple priorities delay guarantee. A Multi-Input Multi-Output (MIMO) system model for Web server was proposed with decentralized self-tuning controllers based on decentralized control theory and Self-Tuning Control (STC) theory. These controllers could dynamically adjust the number of worker threads, which handled different priority requests to ensure that the higher priority requests were processed faster and the average delay ratio of different priority was maintained the same as settings. The parameters of model and controllers were updated according to the result of online identification. The results of simulation tests indicate that proportional delay guarantee can be maintained on the Web server in the closed-loop system even if the number of concurrent client connections change abruptly under overload conditions.

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