Full
CHEN Junhao (1993-), male, Doctoral candidate. E-mail: 359622670@qq.com
Outline
A phononic crystal coupled with the acoustic black hole structure was proposed based on the local resonance theory. The low frequency band gap was widened by utilizing the low frequency, broad band gap, and multi-modal properties of the acoustic black hole structure. The energy band structure, eigenmodes and attenuation characteristics of the phononic crystal were calculated by the finite element method. The generation mechanism of its band gap was analyzed, and the influence of the geometric parameters (i.e., the structural parameters of the acoustic black hole) on the band gap was discussed. The results show that the phononic crystal has multiple band gaps at 1 600 Hz, and the first complete band gap ranges from 12 to 805 Hz. The band gap coverage below 40 Hz is 70%, and the band gap coverage within 1 600 Hz reaches 97.3%. The starting and cut-off frequencies of the first complete band gap are mainly determined by the vibrational modes of the scatterer and the acoustic black hole structure. The starting frequency of the first complete band gap increases with increasing the height of the acoustic black hole structure short side. The width and short side height of the acoustic black hole structure and the height of the short plate have an effect on the cut-off frequency and the width of the first complete band gap.
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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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