基于Plant Simulation的后桥线仿真优化

以F公司后桥装配线为例,针对装配线存在的生产效率低、等待时间长、忙闲不均等问题,在精益思想的指导下根据ECRS原则对装配线的瓶颈工序进行改善,取消不必要的工艺流程,对工人行走路线进行重新规划。另外,对装配线的任务进行重新分配。用Plant Simulation仿真软件对装配线改善前后进行对比分析,结果表明,优化后的装配线节拍降低,日最大产能提高,平衡率增加。     

越江管道下穿的防汛墙结构设计

重要的越江管道关乎人民的生命和财产安全，越江管下穿防汛墙的布局屡见不鲜。以上海市两条越江供水管道为例，根据越江管道相关的保护规定，划定其两侧的控制范围和保护范围；分别采用优化的桩基承台结构和原状土地基处理的方式，给出管道下穿范围防汛墙的结构设计方案，并采用圆弧滑动法验算了结构的合理性。为类似的防汛墙设计，提供一种思路和方法。     

生态袋在上海市河道护岸中的应用分析

河道的生态治理是生态文明建设的重要内容,河道护岸正在由传统型向生态型转型。作为生态型护岸的一种型式,生态袋在上海松江、浦东、嘉定等多条河道中都有所应用。根据现场调研情况,剖析生态袋护岸的应用技术要点,阐述在应用过程中存在的问题,并提出相应对策以供类似项目参考。     

土工合成材料在上海市生态护岸应用的调研

根据由上海市水务局组织的生态护岸调研成果的基础上,系统总结了土工合成材料在上海市生态护岸建设中的应用情况,分析了生态袋和水土保护毯在生态护岸应用中的技术要点、适用条件、限制条件,同时针对存在的问题开展了对策分析,可为今后上海市生态护岸建设中土工合成材料的实际应用提供参考。     

静压下考虑腔压的吸声覆盖层吸声性能分析

[目的]潜艇外壳表面敷设的水下吸声覆盖层在高静水压力作用挤压后的形状、材料参数都会发生改变,使吸声性能受到较大影响,故研究此影响对于潜艇声隐身性具有重要意义.[方法]考虑空腔内压力对静压下覆盖层形变的作用及吸声性能的影响,基于轴对称有限元仿真,计算含圆柱形空腔水下吸声覆盖层的单胞变形;将形变量导入吸声覆盖层的一维理论模...     

Characteristics and calculation method of sound radiation of cylindrical shell with porous sound-absorbing material under acoustic excitation北大核心CSCD

［Objective］This paper aims to study the characteristics and calculation method of the vibration and sound radiation of single ring-stiffened cylindrical shells with porous fiber composite materials installed in the inner wall under acoustic excitation. ［Method ］ Based on the equivalent fluid theory model of Johnson–Champoux–Allard (JCA) and the transfer matrix of the multilayer medium, a theoretical formula of the sound absorption coefficient of multilayer sound absorption structures is derived. The three methods for calculating the vibration and sound radiation of a single ring-stiffened cylindrical shell with porous fiber materials under acoustic excitation, namely acoustic solid modeling of porous media, finite element model combined with theoretical formula and imposition of impedance boundary on sound absorption coefficient, are then verified and compared. Finally, the influences of sound-absorbing material's thickness, backed-air gap, static flow resistance, and material arrangement order on the acoustic absorption performance of the cylindrical shell are investigated. ［Results］The results show that laying porous fiber composite materials on the cylindrical shell internally can reduce the vibration and acoustic radiation of cylindrical shell structure. The sound absorption coefficient curve can quickly and effectively predict the resulting trend of the vibration and sound radiation of the cylindrical shell. ［Conclusion］The acoustic absorption performance of sound absorption structures can be effectively improved through the rational design of their properties and arrangement order of the sound-absorbing materials in order to achieve the purpose of vibration and noise reduction. © 2023 Chinese Journal of Ship Research. All rights reserved.