Compressive and tensile structural elements are disclosed having an enclosure with walls surrounding a cavity. The second sampling capacitor stores a non-ideal error value to offset the non-ideal effect of the operational amplifier imparted on the sensing value. Vehicle matches are then created, published, and shared between users. Second ends of the handles are pivotally connected. According to another aspect of the invention, a hollow tube surrounding an optical fiber containing a long-period grating is sealed at each end with a glass plug. The protective layer receives projection of a light source and is agitated to release free radicals to decompose and absorb organic substances in the air to eliminate toxic chemical substances in the air.