Piezoelectric generator using an impact hammer can achieve a high efficiency by using the vibration of a piezoelectric plate. To achieve high efficiency it is necessary for the piezoelectric plate to have a high electro-mechanical coupling factor k and high Q.Therefore, in this study the generator using a thin plate of 140" rotated Y-cut LfibO, with an inverted domain is proposed to achieve for a high efficiency. The efficiency of the piezoelectric generator is 78% for this new LiNbO, generator and 65 % for a conventional PZT generator. The total efficiency including the impact hammer is 55%.A multilayer LiNbO, element bonded with glue is tested. The efficiency of piezoelectric generator is 70%. It is confirmed that these new generators are effective.

A group analysis of a class of drift-diffusion systems is performed. In account of the presence of arbitrary constitutive functions, we look for Lie symmetries starting from the weak equivalence transformations. Applications to the transport of charges in semiconductors are presented and a special class of solutions is given for particular doping profiles. 0305-4470/99/457953+11$30.00

No abstract

No abstract