Abstract: The present invention relates to a computerized parking meter system which comprises a host computer and a plurality of parking meters. Each parking meter is provided with a supersonic metal sensor to register parking time, to calculate parking fees and to automatically detect whether a specified parking space is available for a car whereby overtime parking can be accurately recorded. The parking meters are connected to the host computer over power lines.

Abstract: A linear-motion wiper structure comprising a multistage hydraulic cylinder arm which can be driven by a transmission mechanism having both vertical and horizontal displacement function whereby a blade, which is driven by the arm, can wipe on the windshield in a linear reciprocating motion so as to completely clear the drops of rain on the windshield, and this may provide a clear vision for users who drive in the rain.