Subjects: Traffic and Transportation Engineering >> Ship Engineering submitted time 2024-03-23
Abstract： In recent years, there has been an increasing demand for higher detection and classification accuracy of ship targets to enable safe ship navigation, driving the development of ship intelligence. However, the performance of deep learning-based ship target detection algorithms is affected by the optical imaging process of ship targets, which can be easily disrupted by environmental factors such as wind, current, rain, and fog. Additionally, the diverse range of ship types, morphologies, and sizes pose challenges for accurate detection and identification of ship targets. To address these challenges, this paper proposes a multi-scale neural network-based target detection method for improving the accuracy of ship target detection in optical images. The proposed method employs a Convolutional Neural Networks (CNN) to extract image features. The improved backbone of CSPDarkNet and multi-scale network is used to realize the accurate detection of the ship-borne optical camera on the water ship target, and the detection accuracy of the model for small targets and dense targets is improved. Furthermore, label smoothing to prevent overfitting, and non-maximum suppression to reduce repetitive detections. Experimental results demonstrate that the proposed model achieves accurate detection of ship targets on water and can be used for the detection of small and intensive targets. The mean average precision (mAP) of the proposed method on the Ship-Detection dataset reaches 84.80, which outperforms previous research methods such as Faster-RCNN, DINO and offers greater potential for practical applications.
Peer Review Status:
Awaiting Review
Subjects: Traffic and Transportation Engineering >> Ship Engineering submitted time 2018-03-30
Abstract： The hydroelastic behavior of very large floating structures (VLFSs) is investigated based on the proposed multi-modules beam theory (MBT). To carry out the analysis, the VLFS is first divided into multiple sub-modules that are connected through their gravity center by a spatial beam with specific stiffness. The external force exerted on the sub-modules includes the wave hydrodynamic force as well as the beam bending force due to the relative displacements of different sub-modules. The wave hydrodynamic force is computed based on three-dimensional incompressible velocity potential theory, and the boundary element method with the free surface Green function as the integral kernel is adopted to numerically find the solution. The beam bending force is expressed in the form of a stiffness matrix. The coupled motion equation is established according to the continuous conditions of the displacement and force. The motion response defined at the gravity center of the sub-modules is solved by the multi-body hydrodynamic control equations, then both the displacement and the structure bending moment of the VLFS are determined from the stiffness matrix equations. To account for the moving point mass effects, the proposed method is extended to the time domain based on impulse response function (IRF) theory. The accuracy of the proposed method is verified by comparison with existing results. Detailed results through the displacement and bending moment of the VLFS are provided to show the influence of the number of the sub-modules, and the influence of the moving point mass.
Peer Review Status:Awaiting Review
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