There are difficulties in obtaining accurate modeling of ship trajectories with traditional prediction methods. For example, neural networks are prone to falling into local optima and there are a small number of Automatic Identification System (AIS) information samples regarding target ships acquired in real time at sea. In order to improve the accuracy of ship trajectory predictions and solve these problems, a trajectory prediction model based on support vector regression (SVR) is proposed. Ship speed, course, time stamp, longitude and latitude from AIS data were selected as sample features and the wavelet threshold de-noising method was used to process the ship position data. The adaptive chaos differential evolution (ACDE) algorithm was used to optimize the internal model parameters to improve convergence speed and prediction accuracy. AIS sensor data corresponding to a certain section of the Tianjin Port ships were selected, on which SVR, Recurrent Neural Network (RNN) and Back Propagation (BP) neural network model trajectory prediction simulations were carried out. A comparison of the results shows that the trajectory prediction model based on ACDE-SVR has higher and more stable prediction accuracy, requires less time and is simple, feasible and efficient.

Existing maritime trajectory prediction models are faced with problems of low accuracy and inability to predict ship tracks in real time. To solve the above problem, an online multiple outputs Least-Squares Support Vector Regression model based on selection mechanism was proposed: (a) converting the traditional Least-Squares Support Vector Regression's single output to multiple outputs, aiming at the problem that the single-output of the traditional Least-Squares Support Vector Regression model is difficult to apply to complex multiple features prediction scenarios, (b) reducing the high computational complexity of matrix inversion calculations using an iterative solution, in order to solve the problem of poor real-time performance, (c) determining whether to use online model based on the characteristics of different trajectories, and (d) removing initial samples least affecting the model to alleviate the impact of large increases in the number of new samples on computational complexity. The model was simulated using the automatic identification system tracks of Tianjin port in March 2015. The calculation accuracy and efficiency of this model was verified by comparing the predicted results of the proposed model with the recurrent neural network-long short-term memory, back propagation neural network, and traditional Least-Squares Support Vector Regression models. In sum, the proposed model is highly accurate in online and real-time prediction of a target ship's trajectory when sailing at sea. In particular, it can sustain high prediction accuracy in the case of smaller data samples. The real-time predicted trajectory can assist the generation of ship collision avoidance decision-making.

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Described herein is a cascade Lewis acid-promoted intramolecular Friedel–Crafts-type imidoylation and Rh(iii)-catalyzed C–H activation/annulation of benzimidoyl chlorides and alkynes, providing a divergent synthetic shortcut to 7H-dibenzo[de,h]quinoline analogues.