In the background of high-power propulsion application on ships and existing uncertain electromagnetic and vibration features of multiphase fractional-slot concentrated-winding permanent magnet (PM) motor, the electromagnetic design and analysis methods of six-phase fractional-slot concentrated-winding PM motor are presented. Four different pole and slot combination schemes are sifted out, and air-gap magnetic field and electromagnetic force of these four motors are studied in contrast. On the basis of the above, a 20-kW prototype of six-phase fractional-slot concentrated-winding PM motor with 48 slots and 44 poles is designed and manufactured, and its electromagnetic and vibration performances are tested through experiments. The test results are in good agreement with calculations, which could guide the development of high-power ship propulsion.

Underwater visual perception is degraded by wavelength-dependent absorption and scattering, the effects of which vary with the camera-to-scene distance. Many underwater image enhancement methods nevertheless apply image-level transformations or use region-wise statistics with discrete boundaries. Such control can make it difficult to preserve near-field appearance while improving far-field visibility, particularly when degradation changes gradually across the scene. We propose a Depth-Aware Underwater Image Enhancement (DUIE) framework that uses relative depth as a spatial prior for continuous enhancement control. DUIE first derives two complementary candidates through foreground- and background-specific statistical color compensation and refines both candidates with a lightweight Nonlinear Activation-Free (NAF)-based network. Its principal learned component jointly maps the input RGB image and an estimated relative depth map to a continuous pixel-wise fusion coefficient. A depth-weighted Laplacian pyramid then blends the refined candidates at multiple scales, replacing the binary mask fusion used by region-wise enhancement with smoother spatial control. The framework therefore combines a physics-inspired depth cue, interpretable statistical candidates, and learned local refinement without explicitly inverting a complete underwater image formation model. Experiments on three real underwater datasets show that DUIE obtains the best overall set of perceptual and edge-based scores among the compared methods, while qualitative results indicate balanced color correction, visibility, and structural detail.

The rim-driven device (RDD) integrates the motor and the impeller, which can achieve shaftless, modular, and integrated operation of the turbomachinery system and has broad application prospects. To reduce the axial length and radial thickness of the RDD, a motor with a thin-yoke wide-tooth fractional slot concentrated winding stator and a coreless Halbach permanent magnet array rotor is designed. Theoretical and finite element simulation analyses of its air gap magnetic field characteristics were carried out. The results show that, for the thin-yoke wide-tooth fractional slot concentrated winding permanent magnet motor, the harmonic magnetic field generated by the magnetic poles should mainly consider the magnetic field components produced by the interaction between the harmonic magnetomotive force of the magnetic poles and the constant air gap specific magnetic permeability, as well as the magnetic field components generated by the interaction between the fundamental magnetomotive force of the magnetic poles and the fundamental and second-order harmonic air gap specific magnetic permeability. The harmonic magnetic field generated by the current should mainly consider the magnetic field components produced by the interaction between the harmonic magnetomotive force with a small number of pole pairs (NOPP) and large amplitude generated by the current and the constant air gap specific magnetic permeability. Compared with radial magnetic flux density, tangential magnetic flux density has the same NOPP and frequency components, with a phase difference of 90°. The fundamental amplitude difference between them is larger, while the harmonic amplitude difference between them is smaller.