Abstract: A monitoring and early warning system based on the Internet of Things for an ancient building includes an information acquisition system, a service platform and a user side. The information acquisition system is configured to acquire state data of the ancient building and upload the state data to the service platform by means of a 4G/5G gateway. The user side is integrated in a visualization device for a user to manage, analyze and interact with the acquired ancient building data, and the user side includes a monitoring module, a pre-alarm module, a management module and an expert module. The service platform is of a duster system integrating a plurality of applications, caches and database servers. The expert module is of a Res-long short-term memory (Res-LSTM) neural network model for evaluating a crack state of the ancient building.

Abstract: A non-invasive time domain reflection probe calibration method includes: using different volume ratio of ethanol and deionized water mixed solution to calculate a test target's medium weight coefficient and waveguide length of the non-invasive time domain reflection probes; using different concentrations of NaCl solutions to calibrate a waveguide geometric dimensioning of the non-invasive time domain reflection probes; preparing compacted soil samples with known different moisture contents and densities, and calibrating a correlation parameter of compacted soil samples' dielectric constant and conductivity with moisture content and density. The method not only determines the sensitivity of the test target medium of the non-invasive time domain reflection probes, but also obtains the waveguide length and geometric dimensioning of the probe, and realizes an accurate test of moisture content and density of the soil.