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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/80152

    Title: 高效率異質性時序資料表示法辨別系統;An Adaptive System for Effectively and Efficiently Representing Heterogeneous Time Series Data
    Authors: 曾翊昇;Tseng, I-Sheng
    Contributors: 土木工程學系
    Keywords: 時間序列資料;時序資料表示法;效能評估;群聚;time series;representation;performance evaluation;clustering
    Date: 2019-08-08
    Issue Date: 2019-09-03 12:14:29 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 時間序列資料為按時間順序儲存的一連串測量相同事件類型的資料,時間序列資料存在於許多領域中,例如股票市場的波動、感測器的數據、醫學和生物資訊等。由於時間序列資料的特性包含(1)資料持續產製、(2)高維度、及(3)龐大的資料量,若直接使用原始時序資料進行分析及儲存,其效率低且成本高。因此,為了有效管理時間序列資料,採用時序資料表示法(representation)取代原始時間序列,可以減少原始時間序列的資料量及維度,但同時保留其時序資料特徵。然而,針對時序資料表示法的壓縮效率及資訊損失表現而言,不同時序資料表示法適合於某些特定時序資料類型,且時間序列資料類型廣泛且多樣,如溫度、溼度、速度、位置、震動、壓力等,這代表無法僅使用單一種表示法有效管理所有類型的時間序列資料。為了解決這個問題,本研究旨在提出一系統,該系統可以有效率地判斷不同類型的時間序列最合適的表示方法。具體而言,本研究針對每個訓練時序資料進行不同表示法的效能評估,進而確定每個訓練時序資料最合適的表示法。為了進一步提升系統效率,將訓練資料進行群聚並選出各群聚最具代表性時序資料。爾後,每當獲取未辨識之時序資料,系統將計算此時間序列與每個群聚代表的相似性,用以間接識別此時序資料最合適的表示法。最後,實驗結果顯示,所提出的系統在不同的參數設定下,能夠為46%至76%的時間序列數據辨別出最合適的表示法。對於其餘的時序資料,系統所選表示法與實際上最合適表示法相比差異僅小於2.19%。此外,實驗成果顯示,所提系統在辨識最合適的表示法上,較傳統方法快17至300倍的效率。;A time series data is a collection of measurements obtained sequentially, which is common in many application domains, e.g., fluctuations of stock market, observations from sensor networks, medical and biological signals. Since time series data usually contains large number of data points, i.e., high-dimensionality, directly dealing with such data in its raw format is very expensive in terms of processing and storage loading. To effectively and efficiently manage time series data, several representation methods were proposed. Representation methods can reduce the dimensionality of a time series data while preserving its fundamental characteristics. However, each representation method is most suitable for certain time series data types in terms of compression rate and information loss, which means no single method is effective enough for all possible types. Therefore, this study aims at proposing a system that can identify the most suitable representation method for different types of time series data. To be specific, this study first conducts an extensive performance evaluation to identify the most suitable representation methods for each training time series data. Afterward, by computing similarities between a new time series and training time series, the system can determine the most suitable representation method for the new time series data. Finally, our experimental result shows that the proposed system can identify the most suitable representation method for 46% to 76% of time series data. For the remaining time series data, the evaluation results also show that the selected representation can produce acceptable results with only less than 2.19% difference comparing to the best representation method. In addition, the experimental result demonstrates that the proposed system can identify the most suitable representation 17 to 300 times faster than the naïve solution.
    Appears in Collections:[土木工程研究所] 博碩士論文

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