近來在無線通訊與電子技術的進展下, 使得無線感測器這種低成本、低耗電的多功能偵測儀器漸漸的普及開來。這種微小的無線感測器的功能包含：偵測資料、資料處理、無線通訊。藉由一大群的無線感測器部署在環境週遭收集環境資料, 透過彼此的互相溝通傳輸可以將資料傳回特定的位置。

　　使用者會關心到底sensor nodes部署的環境之中, 特定的特徵資料發生在哪些區域。利用sensor network找尋並詳細的紀錄這些跟著時間改變的特徵區域, 可以省力且快速的幫助科學家或其他專業人員了解是什麼因素影響這些特徵區域的分佈。複合特徵查詢, 是指一種要找在哪些區域中同時具有多種不同的特徵的查詢。複合特徵查詢在sensor applications裡面是相當普遍的, 例如生物學家觀察鳥類棲息地、自動化環境控制系統, 所以在這些sensor applications裡面, 處理複合特徵查詢便成為一個相當關鍵的運算。

　但是因為sensor nodes有限的電源, 必須在進行複合特徵查詢的處理時盡量的減低傳輸的次數; 而且環境中的現象會隨著時間變動, 要能隨時抓住各個特徵區域的變化情形。本論文提出了一個可以在監測環境不斷變動的環境中, 有效率處理複合特徵查詢的演算法。我們根據sensor nodes所偵測到的資料, 來決定要如何建造處理composite feature discovery的searching structure, 才能節省最多的能源。同時也利用feature分佈的特性, 調整searching structure使能在收集這些composite feature data時能夠有好的aggregation效果。最後我們也以實驗的結果證明我們所提出的方法多數的情況下都有很好的表現。

　In the past few years, due to the development of wireless communication and microelectromechanical system technology, the wireless sensor has been an emerging technology. The functions of this tiny wireless sensor include: detecting data, data processing, wireless communication.Deploying a lot of wireless sensors in the environment, we can collect those detected data via sensor nodes.

　Using sensor networks to find and record the time-changing feature regions can help scientists and other professionals realize what factors influence the distribution of these feature regions. Composite feature query is a query that finds which regions have multiple features simultaneously.

　Because of the limited energy of sensor nodes and dynamic environment, we must reduce the communication cost during composite feature query processing. In this thesis, we propose an algorithm that can efficiently process composite feature queries in a variable environemnt. According to the detected data by sensor nodes, we build an efficient searching structure for composite feature discovery in a most energy-saving manner. Finally, the performance results show that the proposed algorithm indeed performs better than other traditional methods in most situations.

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