Ryoji Fukuda

Acoustic cluster control of noise radiated from a planar structure

Acoustic cluster control is proposed for the purpose of achieving global sound attenuation of a planar structure. First, acoustic cluster filtering using a point sensor array is presented, which enables the grouping of sound radiated from a target object into a set of clusters, such that each cluster possesses the same common characteristics. This allows the possibility of extracting the cluster of interest without causing observation spillover. Based on the principle of reciprocity, cluster actuation using a point source array is then presented. Driving the source array in accordance with a proposed control law, the excitation of the designated cluster is performed without causing control spillover. Moreover, by combining both acoustic cluster filtering and acoustic cluster actuation, acoustic cluster control may be performed. In implementing acoustic cluster control, the necessary and sufficient condition for the acoustic cluster control is illustrated. It is also shown that the sound radiated from a planar structure may be captured in appropriate acoustic cluster filtering so that acoustic cluster control may be implemented. Experiment was conducted demonstrating the capability as well as the validity of the acoustic cluster filtering, actuation, and control for suppressing the noise radiated from a rectangular panel.

On the Smart Cluster Sensor.

This paper concerns the smart cluster sensor for distributed parameter structures using a distributed parameter PVDF film. With an aim to extract the particular cluster the structure has, to which all the vibration modes belonging to possess the same characteristics in common, the smart cluster sensor that has a potential to deal with an infinite number of structural modes is presented. First, this paper begins by introducing the neccessary condition for cluster filtering to be implemented. Then, by utilizing the PVDF film, the shaping function for the smart cluster sensor is shown, enabling the extraction of the targeted cluster of a structure. The output of the smart cluster sensor is found to be written as using the Fresnel integrals. The fundamental properties of the smart cluster sensor such as the dimension and direction of the sensor are discussed. Finally, the experiment using a simply supported rectangular panel is conducted, demonstrating the validity of the proposed smart cluster sensor.