Polyethylene pipelines have been widely used in the construction of urban pipelines. Due to the non-magnetic and non-conductive properties of polyethylene pipelines, traditional metal pipe positioning techniques are unable to effectively detect polyethylene pipelines. To improve the positioning accuracy of polyethylene pipelines, this paper proposes a pipeline positioning method considering the attenuation characteristics of acoustic wave. The proposed method combines active acoustic positioning technology with the resonance characteristics of pipelines, which can accurately locate the horizontal position and depth of pipelines simultaneously. Firstly, based on the theory of acoustic wave attenuation, the solution of the acoustic wave equation in non-ideal media is derived. Then, the amplitude attenuation characteristics of acoustic waves in a buried polyethylene pipeline are analyzed using finite element simulation. By observing the maximum amplitude of acoustic signals, the horizontal direction of buried polyethylene pipelines can be effectively determined. To determine the depth of buried pipelines, the resonance phenomenon is utilized and the attenuation of acoustic waves is considered to obtain the mathematical model. The largest error of simulation results is 2% for horizontal direction, and 7.8% for depth position, indicating the proposed method can effectively locate the buried pipeline. Finally, a complete pipeline excitation and data acquisition system is established through an on-site experiment, and the experiments are conducted under various burial depth conditions. The experimental results show that the horizontal positioning error and depth positioning error are both less than 8%, indicating the proposed method can accurately locate the buried pipeline.

Interior Permanent magnet synchronous motors (IPMSMs) have become the preferred powertrain solution for electric vehicles due to their exceptional performance characteristics. However, the high-frequency electromagnetic noise generated during motor operation poses a significant challenge to occupant comfort within the vehicle. This study provides a comprehensive analysis of the electromagnetic forces, modal characteristics, and vibration noise for a 12-pole, 36-slot IPMSM, incorporating theoretical and simulation-based approaches as well as modal tests. By innovatively combining orthogonal experimental design with nonparametric regression techniques, a response surface model is developed to accurately characterize and optimize the radial electromagnetic force harmonics of the motor. The optimization results reveal a significant 37.7 % reduction in the motor’s surface vibration velocity and an 8.5 % decrease in peak noise levels, successfully meeting the engineering objectives for vibration and noise attenuation. This study not only contributes to the advancement of noise control technologies in electric vehicle power systems but also provides novel insights and methodologies for motor design, offering significant practical value and engineering relevance.

This study proposes a multiphysics coupling optimization methodology to mitigate electromagnetic noise and cogging torque in external rotor permanent magnet synchronous motors. A slot-pole interaction analysis model is developed, incorporating nonlinear magnetic permeability modulation effects, to elucidate the spatiotemporal distribution characteristics of electromagnetic forces and their resonance mechanisms with structural modes. A novel energy-based method for cogging torque calculation is introduced, achieving a 20% improvement in computational efficiency while maintaining numerical errors below 2% . Furthermore, a cylindrical shell vibration model based on nodal force mapping and a boundary element-based acoustic radiation prediction framework are established. Multiobjective optimization leveraging response surface methodology and a modified particle swarm optimization algorithm is employed to quantify the impact of temperature gradients on permanent magnet performance and nonlinear synergistic effects among parameters. Postoptimization results demonstrate a significant reduction in overall sound pressure level to 27.69 dBA under rated conditions and a 38.5% decrease in cogging torque, validating the effectiveness of the proposed electromagnetic-structural-acoustic codesign approach. This work provides a systematic framework for multiphysics collaborative optimization in high-performance motor design.