The influence of fuel injection pressure on smoke emission value is comparatively complicated, while its influence on noiselevel is comparatively small.
气门间隙增大，碳烟排放量增大，但对噪声水平的影响则不是十分显著；
2
The distance between the acoustic-emission source and the receiving transducer, and the background noiselevel are primary factors in selecting a particular frequency band.
声发射源与接收讯号传感器间的距离以及环境噪声的电平是选择频带的主要依据。
3
The advantages and disadvantages of two major types of diesel engines, in the aspects of exhaust gas emission, economy in use and noiselevel and the like, are discussed.