“…However, simple functions may not appropriately represent the relationships between influencing factors and dam displacement. To solve this problem, machine learning algorithms, such as support vector machine (SVM) (Su et al, 2015), extreme learning machine (ELM) (Kang et al, 2017), neural network (NN) (Mata, 2011), long short-term memory (LSTM) network (Liu et al, 2020), random forests (RF) (Dai et al, 2019), boosted regression tree (Salazar et al, 2016), and relevance vector machine (RVM) (Chen et al, 2020), have been shown to possess strong data mining abilities aimed at nonlinear implicit relations and have been employed to establish monitoring models. Meanwhile, based on the multi-scale characteristics, the long term measured displacement time series can be separated in the frequency domain into several components by the wavelet decomposition and empirical mode decomposition, and so forth, and according to the same frequency of effect component and its influencing factor, these components can be distinguished, by which the tendency component is usually defined as the time effect displacement (Correˆa et al, 2016;Fu et al, 2019;Su et al, 2018;Wang et al, 2018).…”