Abstract: The present invention discloses a branch optimization method for execution of a big data ETL model. The necessity of model execution can be analyzed according to the update characteristics of raw data sets and the characteristics of the ETL model; and optimization judgment is carried out on a plurality of operator branches of the ETL model, and for branches with lower update frequency, a middle repeated calculation process is skipped in a manner of reconstructing a cache table, so that the repeated execution rate is reduced from the operator aspect, the execution efficiency of the ETL model is improved, and the big data analysis is carried out more efficiently.

Abstract: The present invention discloses a ship wandering detection method based on AIS (Automatic Identification System) data. According to acquired AIS trajectory data of a ship, wandering behaviors of the ship are detected according to the massive trajectory data, the wandering behaviors of the ship are classified, and relationships between trajectories of four typical abnormal movement behaviors of the ship and defined variables are summarized. The detection for the wandering behaviors of the ship can provide decision support for maritime safety supervision, so as to enhance the safety of maritime traffic and ensure the safe navigation of the ship, which has great significance to promote the safety, efficiency and smoothness of maritime transportation.