Abstract
The ancient murals show multiple types of damage, which include pigment-layer disruption that endangers building stability yet proves difficult to fix. A controlled temperature-humidity cycling device was employed to simulate accelerated mural aging while enabling synchronized multi-sensor monitoring. The collected signals were processed through an integrated pipeline comprising autoencoder-based feature extraction, Gaussian anomaly detection, and fuzzy comprehensive evaluation. The results demonstrate three key findings: (1) acoustic emission effectively monitors the complete process of salt dissolution and crystallization; (2) the autoencoder-Gaussian anomaly detection system with fuzzy grading effectively reduces noise to detect faint events which enables the tracking of gradual damage progression; (3) salt migration and damage development occur at different rates based on temperature and humidity fluctuations yet stable environmental conditions reduce the rate of damage progression. The framework enables fast diagnosis and precise severity measurement, allowing rapid identification of early-stage deterioration changes associated with salt activity.
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Acknowledgements
This research was supported by the Shaanxi Provincial Key R&D Program “Dynamic Monitoring and Early Warning of Micro-Defects in Mural Pigment Layers Based on Acoustic Sensing” (Project No. 2025SF-YBXM-145); the Shaanxi Provincial Key Special Project for Science and Technology Innovation in Cultural Heritage Conservation and Utilization, “Comprehensive Study on the Stability of Tomb Murals Based on Environmental Field Variations” (2022LL-ZD-01); and the Open Project of the Key Scientific Research Base of the State Administration of Cultural Heritage for Mural Conservation and Materials Science. The authors thank the Shaanxi History Museum for providing mural replicas and access to facilities.
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Lu, Z., Xiao, H., Wang, J. et al. Acoustic emission monitoring research on mural relic pigment-layer disruption under dynamic temperature and humidity loads. npj Herit. Sci. (2026). https://doi.org/10.1038/s40494-026-02560-1
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DOI: https://doi.org/10.1038/s40494-026-02560-1
