A storage system includes local storage and remote storage. The underwater projector includes a first disk-type resonator unit, a second disk-type resonator unit, and a central space. Intervention may include various exception handling actions, including upgrading the level of service, stabilizing the temperature of the package, inspecting damage to the package. A tensioning roller is supported at a free end of the tensioning arm so as to be rotatable around an axis of rotation B and extending parallel relative to the longitudinal axis A. The uniform plate may foe separated from-the periodic acoustic-grating by a resonant cavity. An encoder main body for measuring the displacement magnitude of a measured object includes a rotation detection portion for counting n rotations of the measured object and a displacement magnitude detection portion for measuring the displacement magnitude of the measured object.