Control features for a wind turbine that control the turbine over a range of wind speeds and under triggering conditions with reduced noise, cost, and reliability issues associated with other such controls. Accordingly, compressed air passing through the bypass passage can be supplied uniformly into a tail portion of the combustor, and unevenness of temperature distribution in a cross section of the combustor tail portion can be reduced. The valve membrane is in the form of a conical-shaped diaphragm formed integral with the tubular valve body. Electrostatic pads can be used to sense rotation. Use of a ferroelectric capacitor according to an embodiment of the present invention, it is possible to hold stable polarization states of ferroelectric domains for a long retention time, and thus data written in the ferroelectric capacitor a long time ago can be accurately written, thereby improving the reliability of a ferroelectric random access memory. The method includes communicating a billing activation event from an order management system to a billing system, the billing system to create or modify a bill corresponding to the subscriber account and providing an order completion notification to the subscriber.