A novel printed triple‐band rectangular ring monopole antenna with symmetrical L‐strips for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications is presented. The antenna is simply composed of a rectangular ring monopole, a pair of symmetrical L‐strips, and a modified T‐shaped stub. By adjusting the positions and the lengths of these structures, three different current paths can be produced at different frequency bands, respectively. On the basis of this concept, a prototype of the triple‐band antenna has been designed, fabricated, and measured. The experimental results show that the antenna obtains the frequency bands of 2.36–2.93, 3.34–3.77, and 4.75–7.28 GHz with 10‐dB return loss, which can cover both the WLAN in 2.4/5.2/5.8‐GHz bands and the WiMAX in 2.5/3.5/5.5‐GHz bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1049–1052, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26733

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Distributed file systems, such as HDFS, DFS, etc., are adopted to support cloud storage and are designed for optimizing large files access. But unfortunately, the problem of massive small files is neglected and seriously restricts the performance of distributed file systems. To improve and even solve the small file problem, in this paper, user access task is defined. The correlations among the access tasks, applications and access files are constructed by the improved PLSA, and the research object is transferred from file-level to task-level. Then, an effective strategy is proposed to improving small file problem in distributed file system. The strategy merges small files in term of access tasks and selects prefetching targets based on the transition probability of the tasks. Finally, the system efficiency analysis model is established and experimental results, compared with original HDFS, HAR and the schemes of Dong, demonstrate that the proposed strategy effectively reduce the MDS workload and the request response delay.