A method and system for evaluating performance of software applications of different web sites. The DPLL is thus capable of respectively attenuating or tracking jitter from an input reference clock. A drive electrode 23 is formed at a boundary between the upper piezoelectric layer 24 and the lower piezoelectric layer 25 and is electrically connected to a source for supplying a drive signal. The first load and the second load are arranged at opposite sides of the gas turbine and the power shaft axially extends through the gas turbine from a first end to a second end thereof.