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In response to the problem of “roaring” abnormal noise in acceleration of a light bus from 2 000~3 000 r/min, a combination of filtering and subjective evaluation is used to confirm that the main source of the noise is the engine’s 7th to 21st order radiation noise at first. Then, based on the “source-path-response” model, the engine reverse towing method is used on the test bench to analyze that the noise is mainly generated by pressure pulsation of the engine cylinder piston in the reciprocating suction and exhaust phase, and technical means such as sound source coverage method are used to identify that the noise radiation emitting from the intercooler outlet pipe. Finally, by optimizing the intercooler outlet pipe’s structure, the pipe wall’s sound insulation is improved. The verification results show that the average articulation index in the problematic area of the vehicle is increased by 5 percentage points, and the sound quality is significantly improved.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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