The peak switching currents of two paralleled MOSFETs turned on/off by one gate driver could differ significantly owing to the mismatch in threshold voltages (V _th ). The passive balancing method described herein employs one inductor and one resistor per MOSFET to force the currents to track with negligible penalty in loss. Sensors, feedbacks, and knowledge of gate-related parameters (like gate charge, polarity of V _th difference, gate impedances, etc.) are not required. The passive components are designed using an inequality involving V _th , rise time, and unbalance percentage. The mismatch in peak currents is reduced from 15% to 1% between SiC MOSFETs tested at 20 A and 300 V with 19% V _th variation.

In response to challenges such as narrow visibility for ship navigators, limited field of view from a single camera, and complex maritime environments, this study proposes panoramic visual perception-assisted navigation technology. The approach includes introducing a region-of-interest search method based on SSIM and an elliptical weighted fusion method, culminating in the development of the ship panoramic visual stitching algorithm SSIM-EW. Additionally, the YOLOv8s model is improved by increasing the size of the detection head, introducing GhostNet, and replacing the regression loss function with the WIoU loss function, and a perception model yolov8-SGW for sea target detection is proposed. The experimental results demonstrate that the SSIM-EW algorithm achieves the highest PSNR indicator of 25.736, which can effectively reduce the stitching traces and significantly improve the stitching quality of panoramic images. Compared to the baseline model, the YOLOv8-SGW model shows improvements in the P, R, and mAP50 of 1.5%, 4.3%, and 2.3%, respectively, its mAP50 is significantly higher than that of other target detection models, and the detection ability of small targets at sea has been significantly improved. Implementing these algorithms in tugboat operations at ports enhances the fields of view of navigators, allowing for the identification of targets missed by AISs and radar systems, thus ensuring operational safety and advancing the level of vessel intelligence.

Based on ship navigational requirements and safety in foggy conditions and with a particular emphasis on avoiding ship collisions and improving navigational abilities, we constructed a fog navigation dataset along with a new method for enhancing foggy images and perceived visibility using a discriminant deep learning architecture and the EfficientNet neural network by replacing the SE module and incorporating a convolution block attention module and focal loss function. The accuracy of our model exceeded 95%, which meets the needs of an intelligent ship navigation environment in foggy conditions. As part of our research, we also determined the best enhancement algorithm for each type of fog according to its classification.

According to the shape and structure characteristics of ray in the ocean, a passive damping anti-rolling device was designed for fishing boats, platforms on the ocean, pontoon, heavy lift vessel and small ships that were used in maritime navigation or offshore operations. The dynamics model of the systems were established using three-dimensional (3D) computational fluid dynamics (CFD) software, the damping characteristics of the anti-rolling device was analyzed. The mathematical equation of mechanical equilibrium that satisfied the damping characteristics were deduced for the first time, and it is verified through numerical simulation analysis. The engineering feasibility and satisfactory anti-rolling effect of the device were demonstrated, and it can be seen from the experimental results that the average anti-rolling effect can reach more than 45% and more than 70% at zero speed.

In this paper, based on the theoretical research of structural modal analysis, different types of phonon crystal modal structures are designed for the first time, and the characteristics and the generation mechanism of the bandgap were studied through theoretical calculations and experiments. According to the phenomenon in the experimental results, we can find that the vibration transmission characteristics of phonon crystal structure α3 are the best, and it is also superior to that of phonon crystal structure α10 (full period structure). Therefore, the comparison of theoretical analysis with experimental phenomena shows that the bandgap generation mechanism should be modal resonance instead of local resonance in the finite periodic structure. The profound reason lies in there is no separate Z direction local vibration mode of periodic structure in the vibration mode of finite structure, and the bandgap of finite structure is the mode superposition torsional resonance mechanism between scatterer and substrate mode.