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Continuous monitoring of natural gamma radiation in air has been carried out, during December 2014 – January 2018, with 1-min cyclic measurement in Prague, Czech Republic using a NaI(Tl) probe. The 214Bi/214Pb ratio as a tracer in rainwater has been investigated to study its variations related to both the ambient dose equivalent rate per hour and the amount of rainfall. A hybrid methodology for time series analysis, composed of the aggregation of two signal decomposition methods (multiple linear regression and empirical mode decomposition) and one forecasting method (support vector regression), has been applied to identify the anomalies in the studied signals in order to better find correlations among them. The results show a strong correlation between the ambient dose equivalent rate and the 214Bi/214Pb ratio values and between both these signals and rainfall amount ≥5 mm/h. Furthermore, the considered descendants of radon are mainly responsible for the overall ambient dose equivalent rate.

The analysis of the Earth's rotation rate time series, from January 1,2012 till December 31,2017, is performed using two different time series analysis methods, both based on signal decomposition joined with forecasting approach. Anomalies in the time series are detected making the comparison between the raw signal and the forecasting one at the 95% confidence interval. The two methods show consistent results and the best is selected according to the evaluation of the prediction uncertainty. Both methods highlight correlations between detected anomalies in the Earth's rotation rate time series and the world's earthquakes occurrence with magnitude ≥7 and/or number of events ≥150 per day, within a time interval of ±10 days from each earthquake event. This study brings an innovation in the analysis of such time series and helps to better understand the extent of this relationship.

•Characterization of the gouache gilding technique of cultural heritage objects.•X ray fluorescence analysis of gilded lead objects and gilded wooden objects.•Application of multivariate analysis and graph theory on X Ray Fluorescence spectra.•Classification and discrimination of gouache gilded objects from Royal Palace of Caserta.•Thickness estimation of the gold layer and preparatory layer by X-ray fluorescence lines ratios.