| 摘要 |
To open a tube 10 filled with liquid 12 in which a stopper 14 has been placed, a device 16 is attached in the tube. This device exposes the liquid to pressure waves containing many harmonic components, preferably consisting of pulse sequences. By means of a controllable flexibility device 28 the harmonic components n are controlled in the resonance frequency for the system's uncompressible type formed by the liquid 12 in tube 10 so that its frequency corresponds to the harmonic component 1 at the resonance frequency for the system's compressible type (in which n is preferably 1, 2 or 3). This permits use of resonances in systems of two types, the compressible type, by using a low excitation frequency (under 20 Hz) which reduces the hazard of rupture or bursting of the tube 10. <IMAGE>
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