Decentralized active vibration control in cruise ships funnels

A huge problem in cruise ships is related to undesired noise and vibrations generated by engines and exhaust stacks. Reduction or suppression of ship noise has traditionally been implemented by passive means, such as by the use of vibration isolation mounts, flexible pipe-work, and interior acoustic absorbing materials. However. while passive devices are effective mostly for attenuating high-frequency noise, they are generally ineffective to suppress low-frequency vibrations. The paper deals with the design of an active standalone device to suppress vibrations on cruise ships funnels. The device can work independently and, matched with others through a decentralized control, can dissipate most of the kinetic energy of the system, thus limiting the propagation of vibration and improving comfort on surroundings.