| 摘要 |
<p>The device has a central cylindrical portion (11) that is provided with two ends. Flanges (12, 13) are disposed at the ends of the central portion, respectively, where the flanges extend across the central portion. Each flange includes a side portion that is shaped and sized to define a membrane, where diameters of the flanges and the central portion are divided by an average thickness of the side portion of the flanges.</p> |
