Embodiments of methods to securely bind a disk cache encryption key to a cache device are generally described herein. The IP network includes a conference server and at least one Call State Control Function. No matter if the top surface or the bottom surface faces downward after having the blades fixed with a shaft of a motor, the area of the front wind-confronting portion or the rear wind-confronting portion confronting air is always such minimized that air drag can be lowered. The asymmetry may be with respect to target element segmentation or structural dimensions. The vibration-insulation member becomes one body with the inner body member, and is interposed between the inner body member and the outer body member so that vibration transmitted from a power plant to a car body may be effectively dampened and absorbed.