In this paper, we report on microelectromechanical system (MEMS) energy harvesters with a diaphragm consisting of a 1-mm-thick lead zirconate titanate (PZT) film formed by the sol-gel method. Electrical power can be generated using the piezoelectric effects of the PZT diaphragm that vibrates in acoustic fields. Harvesters with different diaphragm diameters of 1.5 and 2.0 mm were fabricated. The top electrode covered the entire PZT diaphragm. The measured first resonance frequencies of those diaphragms were 6.02 and 5.72 kHz, and the third resonance frequencies were 24.02 and 18.02 kHz, respectively. The measured frequency spectrum indicated that the induced voltages are larger and more widely distributed for the third resonance than for the first resonance. Those devices generated power of 1:1 Â 10 À11 and 5:1 Â 10 À12 W under the irradiation of 100 dB sound pressure at their third resonance frequencies. #

In this paper, deterioration diagnosis for distribution main pipe was studied using the uniform cylindrical shell approximation and in-plane bending mode. The in-plane bending mode is expected to have high accuracy in detection of deterioration, because the eigen frecuency of the mode is proportional to pipe thickness. First, using the finite element method, the characteristics of in-plane bending mode are investigated. It is confirmed that in-plane bending mode has little small dependence on the pipe length and the boundary conditions at the pipe ends, it appears in the audio frequency bands, and it has linear dependence on the pipe thickness. In addition, formula with two dimensional ring approximation is derived. Moreover, the average thickness and the uniform-cylindrical shell approximation are introduced for deal with the deteriorated pipe. Using the thinning pipe thickness of previous study, validity of the average thickness and the uniform-cylindrical shell approximation were confirmed. On the other hand, actual pipeline has the sub-structure, for example, valve, hydrant, and so on. In order to deal with the coupled vibration between the cylindrical shell and the sub-structure, eigenvalue analysis are conducted using the Semi-Analytical Receptance Method (SARM). The experimental consideration were conducted in case of that the sub-structure non-attached case. The in-plane bending mode is observed experimentally on the actual pipe system and its resonant frequency shows good match with the theoretical values.

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