Abstract: A door system includes a corridor sized to allow humans to move through the corridor, the corridor having a first door located at a first end; a second door located at the second end; a controller operatively connected to the first and second doors for controlling the first and second doors; a first sensor oriented to detect an object on the floor, the first sensor operatively connected to the controller and a second sensor oriented to detect an object above the floor in the corridor wherein the second sensor is operatively connected to the controller and the controller is configured to one of: a) turn off the second sensor when the first sensor detects an object on the floor and b) not respond when the second sensor detects and object above the floor when the first sensor detects and object on the floor.

Abstract: A door system includes a corridor sized to allow humans to move through the corridor, the corridor having a first door located at a first end; a second door located at the second end; a controller operatively connected to the first and second doors for controlling the first and second doors; a first sensor oriented to detect an object on the floor, the first sensor operatively connected to the controller and a second sensor oriented to detect an object above the floor in the corridor wherein the second sensor is operatively connected to the controller and the controller is configured to one of: a) turn off the second sensor when the first sensor detects an object on the floor and b) not respond when the second sensor detects and object above the floor when the first sensor detects and object on the floor.

Abstract: The present invention provides a system and method for detecting changes in the properties of a polymeric material. A frame is hand held against the outside surface of a curved polymeric test specimen, e.g., fluid tank. A transmitting probe attached to the frame emits critically refracted ultrasonic waves that travel longitudinally across the chord of said curved test specimen and are detected by at least one receiving probe attached to the frame. A data processing system measures the travel time of the ultrasonic waves from the transmitting probe to the receiving probe and compares this measured travel time to an expected travel time. Variations in material properties along the penetration path of the ultrasonic waves can be detected from deviation in the measure travel time of the waves from the expected control values. Measuring the temperature of the polymeric specimen allows adjustment of the measured travel time of the waves to account for temperature effects on the polymeric material.