›› 2017, Vol. 29 ›› Issue (4): 213-225.

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The Detection of BDI Index Hidden Periodicities: A VMD-GRGC-FFT Ensemble Methods

Yu Fangping, Kuang Haibo   

  1. Collaborative Innovation Center for Transport Studies, Dalian Maritime University, Dalian 116026
  • Received:2016-08-29 Online:2017-04-28 Published:2017-04-21

Abstract:

It is significant to find out the periodic characteristics of BDI index, the benchmark index of global shipping market, in order to further understand the law of marine freight rate, forecast the trend of global shipping market and so on. In this study, the BDI index hidden periodicities are discussed in depth, and the main innovation points are: Firstly, the theoretical analysis framework of BDI index periodicities division and formation mechanism is proposed, and the BDI index periodicities fluctuation influence factors of three dimensions: demand side, supply side and non-economy factors, are analyzed. Secondly, the framework of BDI index long period, middle period and short period calculation based on VMD-GRGC-FFT is constructed. BDI index modal components are decomposed by means of Variational Mode Decomposition (VMD), the three synthesis components of low, medium and high frequency are reconstructed using Grey Relational Grades Cluster analysis (GRGC), and hidden average periodicities corresponding to the BDI index are detected through the Fast Fourier transform (FFT) model. Thirdly, we collect BDI index day/week/month data in 1985-2015 for empirical analysis. Results show that: the BDI index's long period is about 16 years, middle period is about 2-4 years and short period is about 0.4-0.6 years. At the same time, we predict that in the next few years after 2016, the BDI index will still be in the long period of the depression stage and the middle period of the recovery stage.

Key words: BDI index, periodicity, Variational Mode Decomposition (VMD), Grey Relational Grades Cluster (GRGC), Fast Fourier Transformation (FFT)