Calculation method of underwater acoustic and vibration response of cabin segment based on onshore vibration test北大核心CSCD

[Objective]This paper proposes a method for calculating the acoustic and vibration response of underwater cylindrical shell structures based on land-based vibration test results.[Methods]An axisymmetric boundary element method (BEM) is introduced to describe the radiation acoustic field of the shell. The relationship of acoustic pressure at the nodal point of the generatrix with velocity is obtained by solving the numerical solution of the boundary element integral equation, then the acoustic radiation impedance matrix of the outer surface of the shell and acoustic transfer vector (ATV) are constructed. Based on the assumption that the low-order vibration mode of an underwater cylindrical shell is the same as that of an onshore cylindrical shell, combined with the modes and acoustic radiation impedance matrix of an onshore cylindrical shell, the modal added mass and damping are calculated. [Results]The natural frequency calculation formula of the underwater cylindrical shell is established on the basis of the onshore mode, and the calculation method of underwater vibration response and acoustic radiation characteristics with the vibration response in air as input is obtained based on mode superposition method.[Conclusion ] The numerical results of a typical cylindrical shell with internal structure show that the method meets the engineering accuracy requirements. © 2023 Chinese Journal of Ship Research. All rights reserved.     

汽车侧面碰撞安全性研究探讨

随着我国汽车碰撞安全性研究的不断发展和国内汽车碰撞试验水平的提高,有关汽车侧面碰撞安全性的法规也开始准备颁布实施。本文主要论述我国开展汽车侧面碰撞研究的重要性,并进行FMVSS214和ECER95侧面碰撞法规的对比分析,介绍FMVSS214和ECER95法规中移动壁变形壁障的几何尺寸及其力学性能要求。最后概述抗侧面碰撞的车身结构设计与改进方法。     

噪声地图技术在高速公路噪声污染防治中的应用研究

噪声地图是一种通过声压级分布来体现特定区域或点位噪声强度的声学仿真技术,一般用于医院、学校等特殊声功能区的噪声监测与控制。基于江苏盐靖高速K166段的噪声状况,本研究首次将噪声地图应用于高速公路交通噪声防治方案的设计,通过一般敏感点监测、噪声衰减断面监测及24h连续监测等3种监测方法对该路段进行了系统的环境噪声质量监测,在此基础上建立了噪声地图仿真模型并提出了降噪方案。     

多普勒声呐安装误差补偿方法研究

多普勒声呐利用多普勒频移原理,测量多普勒声呐相对海底的速度,随着测量精度的提高和宽带多普勒声呐的出现,已经应用于多种载体的导航.由于多普勒声呐在换能器安装和在载体上安装时,不可避免出现误差,而安装误差对于测量载体的绝对速度有较大的影响.本文主要研究换能器安装误差、安装角度误差和安装位置的补偿方法,对于提高多普勒声呐的测量精度具有较大的意义.     

Bandgap optimization for chiral acoustic metamaterials based on material selection method北大核心CSCD

［Objectives］This study seeks to expand the bandgap frequency band, reduce the bandgap starting frequency and analyze and optimize the bandgap parameters of acoustic metamaterials. ［Methods］The influence of geometrical and material parameters on the bandgap properties of acoustic metamaterials is analyzed, and a method for maximizing the bandgap width is proposed. The multi-objective optimization problem is converted into a single objective optimization problem by normalizing the bandgap frequency coefficients. Structural material conversion is achieved via the material selection optimization method, and the optimization equations of bandgap parameters are established on the basis of weight-lightening. For chiral acoustic metamaterials, the material properties (density and wave velocity) and geometric parameters (scatterer diameter, ligament thickness and coating thickness) are defined as design variables, and the comprehensive optimization of structural parameters and material selection of acoustic metamaterials based on weight-lightening are implemented. ［Results］The optimization results show that the bandgap width increases by 27.7% and the lower bound frequency decreases by 1048 Hz, thereby achieving the goal of expanding the bandgap width based on lightweight acoustic metamaterials. The acoustic transmission analysis of the finite chiral acoustic metamaterial structure is then carried out to verify the effectiveness of the proposed method. ［Conclusions］The results show that the goal of lightweight acoustic metamaterials can be effectively achieved by integrating the comprehensive optimization of structural parameters and materials. As such, this study provides references for the design of new-type acoustic metamaterials. © 2023 Authors. All rights reserved.     

基于下游引航道口门区流态的隔流墙结构形式优化措施

船闸外侧水流受枢纽下泄不稳定流的影响较大，为解决流速、流态对船舶航行的不利影响，维持引航道水流条件，分析下游引航道不稳定水流的成因，结合近年来建成的隔流墙布置方式和结构形式，通过平面布置、模型试验、资料统计分析等方法，探讨了实体墙、隔流墩、透水孔墙等诸多结构形式对水流条件的影响，研究提出多种引航道隔流墙结构布置形式和优化措施方案。     

船舶低噪声建造工艺发展思考

论证低噪声建造工艺发展的必要性，梳理国内外低噪声建造工艺的发展现状，并分析国内低噪声建造工艺发展的不足，提出船舶低噪声建造工艺发展的思路，旨在为我国船舶低噪声建造工艺的发展进行有益的探索。     

异质结构焊缝检测的相控阵超声全聚焦算法优化

船舶异质结构焊缝检测的相控阵超声全聚焦算法信噪比高、适应性强，但该算法存在超大计算量和伪影等诸多问题。依据声束指向性提出该算法的优化方案。过滤非声束指向性声场中的重构点可大幅提升计算速度，并可优化相同路径默认调取全矩阵中同一幅值的伪影问题。将优化算法用于异质结构，获得高效高质量的检测结果，为满足铝钛钢复合接头大批量在线无损检测的工程需求提供思路。