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The fiber-optic sensor array based on path-matched differential interferometry (PMDI)-time division multiplexing (TDM) offers the advantages of minimal channel crosstalk and high sensitivity. The 3 × 3 optical fiber coupler demodulation is the commonly employed scheme for PMDI-TDM. However, due to the non-ideal characteristics of the 3 × 3 optical fiber coupler and inconsistencies in multi-channel photodetectors, harmonic distortion occurs during signal demodulation. This paper proposes a low harmonic distortion signal demodulation scheme for PMDI-TDM structure fiber-optic sensor arrays based on multi-channel parameter fitting and tracking. This scheme utilizes the random sample consensus (RANSAC) algorithm to accurately obtain the parameters of the ellipse formed by the interference fringes of each element sensor in the system. Furthermore, the multi-channel parallel extended Kalman filter (MPEKF) is used to realize the real-time tracking of multi-channel demodulation parameters. The RANSAC-MPEKF scheme can suppress the influence of outliers, and effectively eliminate the non-ideal characteristics of 3 × 3 coupler and the non-consistency of photodetector, thereby suppressing harmonic distortion of the demodulation results of each channel. The experimental results demonstrate that the proposed scheme can suppress the influence of outliers, .and achieves a demodulation rate ≥500 kHz with minimal resource consumption, making it particularly suitable for large-scale multiplexing systems with a THD value better than 0.12%.
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http://dx.doi.org/10.1364/OE.550062 | DOI Listing |
Sci Rep
September 2025
Fukushima Renewable Energy Institute, Koriyama, 963-0298, Japan.
This study proposes a novel and computationally efficient method for real-time identification and localization of power quality (PQ) disturbances in microgrids using dynamic Lissajous patterns formed by voltage and current waveforms. Each power disturbance-such as sag, swell, harmonic distortion, and transients-induces a unique geometric deformation in the Lissajous figure, which serves as a visual signature of the event. Key geometric and statistical features, including area, skewness, kurtosis, and centroid deviation, are extracted from these dynamic patterns to construct robust indices for classification.
View Article and Find Full Text PDFThis paper presents a novel multiscale signal processing framework for power quality disturbance (PQD) and cyber intrusion detection in smart grids, combining Non-Subsampled Contourlet Transform (NSCT), Split Augmented Lagrangian Shrinkage Algorithm (SALSA), and Morphological Component Analysis (MCA). A key innovation lies in an adaptive weighting mechanism within NSCT's directional sub bands, enabling dynamic energy redistribution and enhanced representation of both low-frequency anomalies (e.g.
View Article and Find Full Text PDFMicrosyst Nanoeng
September 2025
School of Integrated Circuits and Electronics, Beijing Institute of Technology, Beijing, China.
Piezoelectric MEMS loudspeakers based on cantilever diaphragms have demonstrated promising electroacoustic efficiency and low-frequency sound pressure level (SPL). However, their total harmonic distortion (THD) significantly increases near the first resonant frequency, and high-frequency SPL (above 10 kHz) rapidly decreases due to the resonance frequency and bandwidth limitations, severely affecting sound quality. This work presents a piezoelectric MEMS loudspeaker featuring a 2.
View Article and Find Full Text PDFNMR Biomed
October 2025
Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.
∆B shim optimization performed at the beginning of an MR scan is unable to correct for ∆B field inhomogeneities caused by patient motion or hardware instability during scans. Navigator-based methods have been demonstrated previously to be effective for motion and shim correction. The purpose of this work was to accelerate volumetric navigators to allow fast acquisition of the parent navigated sequence with short real-time feedback time and high spatial resolution of the ∆B field mapping.
View Article and Find Full Text PDFSci Rep
September 2025
Electrical Power and Machines Department, Higher Institute of Engineering, El Shorouk Academy, Cairo, Egypt.
In modern power systems, it is crucial to monitor and detect internal faults in power transformers promptly and accurately to ensure reliability and prevent disruptions. Failure to identify these faults promptly can reduce the transformer's lifespan, cause system disconnection, and compromise network stability. This paper introduces an innovative method for the discrimination, classification, and localization of internal short-circuit faults in power transformers, with a focus on three types of winding faults: turn-to-turn fault, series short circuits, and shunt short circuits.
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