In concurrence with the exhaust system resonance occurs at certain engine rotating speed during testing, the noise level of engine will substantially increase. 内燃机排气系噪声试验中,在某种转速下,排气系发生共振,从而使发动机噪声大大增加。
In recent years, engine upgrades have extended the life of the tankers and increased performance, lowered the noise level, and reduced maintenance costs. 在最近几年里(译注:本文发表于1993年),通过发动机升级已经沿长了加油机的使用寿命并且提高了性能,降低了噪音级别,还减少了维护费用。
The matching relations of dynamic characteristics between the engine mounting system and other sub-systems have a great influence on impro-ving automotive ride performance and decreasing the noise level. 发动机悬置系统和汽车其它子系统固有特性匹配关系对降低整车振动和噪声水平有显著影响。振动和噪声是密切相关的。