An exemplary screw protection cover is provided, which includes a cover head, a cover body and a positioning piece. The construction provides uniform temperature during the cooking process, yet minimizes heat loss after cooking. Audio processing and acoustic echo cancellation are performed on the received speech signals. This results in reduced working time. Substantially balanced forward and axial deceleration produces a trajectory that is characterized by a gyroscopic stability factor that remains highly stable over a given distance of a trajectory. The acknowledgement may further include one or more of a time reference used by the system; and an identification of secondary technologies used by the system.