A security device may include a lanyard, a lanyard retention lock, and connectivity detection circuitry. The fixing bracket includes two sidewalls mounted on two sides of the fan and a connecting wall mounted on a top of the fan. The control unit is connected to a readwrite unit for reading the use history information from the IC tag of the blade case held by the blade case holder and writing the use history information to the IC tag. The metal substrates being stripped also do not undergo corrosion or other damage as a result of the described process. It can be determined that the set of one or more terms corresponds to an element in the document, and the at least one command can be executed on the element in the document. This is accomplished by sensing or observing a system variable, such as speed or motor current, and comparing this measured value to a predicted limit value of the system variable which is based upon the behavior of the system variable when there is no object present.