The motion of ships and marine structures is a nonlinear motion with time series characteristics. The Long Short-Term Memory (LSTM) artificial neural network has the characteristics of memorizing time interval information and processing nonlinear data, which is very suitable for processing such nonlinear motion with time series characteristics. Therefore, LSTM has significant advantages in predicting the very short-term motion response of ships. In this paper, an improved LSTM method for the prediction of very short-term motion response of ships is proposed. This method converts the prediction of ship motion into the prediction of peak and valley values by means of extracting envelopes, which can reduce the data demand of the traditional LSTM model and simplify the complexity of the prediction curve, thereby significantly improving the forecast duration. In this paper, the improved LSTM was used to predict the regular wave curve, irregular wave curve and real ship motion curve. The results show that the improved LSTM prediction method can enlarge the maximum forecast duration of the traditional LSTM model from 6~8 s to about 20 s, and has ideal prediction results for special signals such as abrupt signals, which has high practical value.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |