A security system and method for granting multi-level access to data items in a distributed network. The wind turbine includes a rotor rotatably coupled to a generator by the rotor shaft. Said channel transmits output signals compared with an expected value in order to verify the channel correct operation. A width between the two respective loose portions of the two jaws is wider than a width between the two respective clamping portions of the two jaws. This innovative educational method has cross-curricula applications and may be taught and personally tailored to address the specific needs of groups or individuals at any age or instructional level In addition, the method and apparatuses provide a diagnostic tool and a form of assessment which can be used by the individual student, collaborating with others andor the teacher. The subscription portion is associated with a device portion for storing device information, a services portion for storing services information, and a mobile subscription portion for storing mobile subscription information.