Chen Ting-Wang, Wang Likarn
Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 300, Taiwan.
Sensors (Basel). 2025 Aug 15;25(16):5074. doi: 10.3390/s25165074.
Hierarchical clustering analysis is applied to the positioning of two simultaneously-occurring intrusion events in the case of a dual Mach-Zehnder interferometer used for intrusion detection. To simulate the two intrusion events, the sensing fibers of the dual Mach-Zehnder interferometer are heavily knocked at two different positions simultaneously. Then the clockwise (CW) and counter-clockwise (CCW) signals are loaded into a personal computer through a data acquisition module, and analyzed by Fourier transform method for determination of the time delay between the two signals. Hierarchical clustering analysis is then employed twice for dividing the data points in a feature space into several clusters according to the conditions required. To locate the two intrusions, the first clustering analysis is performed on the data points formed by signals detected in a 10 ms time period, with the centroid of the largest cluster being the location of a single intrusion event. Then, 100 pairs of CW and CCW signals detected sequentially are analyzed to give 100 locations. These 100 locations and their CP values (each standing for a ratio of a given spectral amplitude to the summation of the spectral amplitudes over the frequency band of 2500 to 5000 Hz) constitute 100 data points in a feature space for the second hierarchical clustering analysis, which then determines the respective locations of the two intrusion events. In the test of a 1036 m long fiber perimeter, we demonstrated an accuracy to within 21.55 m.
在用于入侵检测的双马赫-曾德尔干涉仪的情况下，层次聚类分析被应用于两个同时发生的入侵事件的定位。为了模拟这两个入侵事件，双马赫-曾德尔干涉仪的传感光纤在两个不同位置同时受到重击。然后，顺时针（CW）和逆时针（CCW）信号通过数据采集模块加载到个人计算机中，并通过傅里叶变换方法进行分析，以确定两个信号之间的时间延迟。然后，根据所需条件，层次聚类分析被使用两次，将特征空间中的数据点划分为几个簇。为了定位这两个入侵点，对在10毫秒时间段内检测到的信号形成的数据点进行第一次聚类分析，最大簇的质心即为单个入侵事件的位置。然后，对依次检测到的100对CW和CCW信号进行分析，得到100个位置。这100个位置及其CP值（每个代表给定频谱幅度与2500至5000赫兹频带内频谱幅度总和的比值）构成特征空间中的100个数据点，用于第二次层次聚类分析，进而确定两个入侵事件各自的位置。在对1036米长的光纤周界进行的测试中，我们证明定位精度在21.55米以内。
