This paper deals with the vibro-acoustic coupling of an irregular enclosure covered with a PZT-bonded panel. The modeling of the system is developed with full consideration of the acoustic-structural-piezoelectric interactions between the actuated panel and the enclosure, along with the modeling of the irregular shape of the enclosure. Simulations are conducted to investigate the effect of the actuation patch on structural modal modification, and subsequently on the structural-acoustic coupling mechanism. Results show that the structural mode shapes can be altered significantly, depending on the patch locations and structural frequency behavior (singlet, doublet or closely coupled), and the patch effect on the coupling density is noticeable, especially when the inclined angle of the enclosure is within a sensitive region. This study provides a more thorough physical understanding of how the PZT patch influences the modal coupling between the actuated panel and the enclosure, which might be useful for all control techniques involving PZT actuated panels.

Long-term exposure to airborne particles may cause potential damage to human health. Until now, many monitoring instruments have been developed, but the loss of airborne particles within the measurement systems has rarely been mentioned. This work was to investigate the loss of particles (10~487nm) when they flowed through stainless, Nylon, Teflon and Tygon tubes, respectively, with carrier gas. Number concentrations of the airborne particles were observed with a Scanning Mobility Particle Sizer (SMPS). Results show that the difference of the size distribution of particles that were generated by electrically heating and flowed through stainless, Nylon and Teflon tubes was less significant, but the number concentrations were all higher than that through Tygon one. While monitoring indoor airborne particles, no significant particle loss could be observed no matter what tube we used. Tube hardness and the temperature of the carrier gas are considered to be two important factors that influence the losses of airborne particles.